U.S. patent application number 15/241600 was filed with the patent office on 2017-02-16 for combustion burner, solid-fuel-combustion burner, solid-fuel-combustion boiler, boiler, and method for operating boiler.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Naofumi Abe, Kazuhiro Domoto, Jun Kasai, Keigo Matsumoto.
Application Number | 20170045221 15/241600 |
Document ID | / |
Family ID | 46968977 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170045221 |
Kind Code |
A1 |
Matsumoto; Keigo ; et
al. |
February 16, 2017 |
COMBUSTION BURNER, SOLID-FUEL-COMBUSTION BURNER,
SOLID-FUEL-COMBUSTION BOILER, BOILER, AND METHOD FOR OPERATING
BOILER
Abstract
Provided is a combustion burner including: a fuel nozzle (51)
that is able to blow a fuel gas obtained by mixing pulverized coal
with primary air; a secondary air nozzle (52) that is able to blow
secondary air from the outside of the fuel nozzle (51); a flame
stabilizer (54) that is provided at a front end portion of the fuel
nozzle (51) so as to be near the axis center; and a rectification
member (55) that is provided between the inner wall surface of the
fuel nozzle (51) and the flame stabilizer (54), wherein an
appropriate flow of a fuel gas obtained by mixing solid fuel with
air may be realized.
Inventors: |
Matsumoto; Keigo; (Tokyo,
JP) ; Domoto; Kazuhiro; (Tokyo, JP) ; Abe;
Naofumi; (Tokyo, JP) ; Kasai; Jun; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES, LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
46968977 |
Appl. No.: |
15/241600 |
Filed: |
August 19, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14007858 |
Sep 26, 2013 |
|
|
|
PCT/JP2012/055850 |
Mar 7, 2012 |
|
|
|
15241600 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23D 2209/20 20130101;
F23K 2203/201 20130101; F23D 1/005 20130101; F23C 2201/20 20130101;
F23C 5/32 20130101; F23C 6/045 20130101; F23D 2201/20 20130101;
F23N 3/00 20130101; F23D 2201/10 20130101; F23N 2221/10 20200101;
F23L 9/00 20130101; F23D 1/00 20130101; F23D 2201/101 20130101 |
International
Class: |
F23D 1/00 20060101
F23D001/00; F23N 3/00 20060101 F23N003/00; F23C 5/32 20060101
F23C005/32; F23L 9/00 20060101 F23L009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2011 |
JP |
2011-081876 |
Apr 1, 2011 |
JP |
2011-081877 |
Apr 1, 2011 |
JP |
2011-081879 |
Jun 22, 2011 |
JP |
2011-138563 |
Jun 22, 2011 |
JP |
2011-138564 |
Claims
1. A solid-fuel-combustion burner that is used in a burner portion
of a solid-fuel-combustion boiler for inputting pulverized solid
fuel and air into a furnace, the solid-fuel-combustion burner
comprising: a fuel burner arranged to input pulverized fuel and
primary air into the furnace; and a secondary air port arranged to
input secondary air from the outer periphery of the fuel burner,
wherein a cross type split member obtained by intersecting a
plurality of inner flame stabilization members in a plurality of
directions is disposed at a front side of a passage of the fuel
burner, and the width of the split member is different for each
direction.
2. The solid-fuel-combustion burner according to claim 1, wherein
three or more cross type split members are disposed in at least one
of a first direction and a second direction, and the center
portions thereof in at least one of the first direction and the
second direction are wide.
3. The solid-fuel-combustion burner according to claim 2, wherein
the cross type split members are wider in the first direction than
in the second direction.
4. The solid-fuel-combustion burner according to claim 2, wherein
the cross type split members are wider in the second direction than
in the first direction.
5. A solid-fuel-combustion burner according to claim 1, the
secondary air input port that ejects secondary air from the outer
periphery of the fuel burner, wherein the fuel burner functions as
an inner flame stabilization and the secondary air port does not
function as a flame stabilization, and a shielding member is
provided in at least one position of the intersecting corners
formed by the intersection of the split members.
6. The solid-fuel-combustion burner according to claim 1, wherein
at least an end portion of the cross type split member in any one
direction of a plurality of directions is removed.
7. A solid-fuel-combustion boiler comprising a
solid-fuel-combustion burner according to claim 1 disposed at a
corner or a wall surface inside a furnace.
8. The solid-fuel-combustion boiler according to claim 7, further
comprising an additional air port/unit for inputting an additional
air downstream of the furnace, wherein the air is divided into the
secondary air port and the additional air port/unit so as to
perform a low NOx combustion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional of U.S. patent application Ser. No.
14/007,858, filed on Sep. 26, 2013, of which is a 371 of
PCT/JP2012/055850 filed Mar. 7, 2012, of which claims foreign
priority over Japanese Application No. 2011-081876 filed Apr. 1,
2011, Japanese Application No. 2011-081877 filed Apr. 1, 2011,
Japanese Application No. 2011-081879 filed Apr. 1, 2011, Japanese
Application No. 2011-138563 filed Jun. 22, 2011, and Japanese
Application No. 2011-138564 filed Jun. 22, 2011, the entire
contents of which is incorporated herein by reference.
FIELD
[0002] The present invention relates to a combustion burner that is
applied to a boiler for producing steam to be used to generate
electric power or to be used in a factory or the like. For example,
the combustion burner is a solid-fuel-combustion burner that burns
solid fuel (pulverized fuel) such as pulverized coal. Also, the
invention relates to a solid-fuel-combustion boiler, a boiler that
produces steam by burning solid fuel and air, and a method for
operating the boiler.
BACKGROUND
[0003] For example, a conventional pulverized-coal-combustion
boiler includes a furnace which is formed in a hollow shape and is
provided in the vertical direction, and plural combustion burners
are disposed in a furnace wall in the circumferential direction and
are disposed at plural stages in the up and down direction. A
fuel-air mixture obtained by mixing primary air with pulverized
coal (fuel) formed by milling coal is supplied to the combustion
burners, and hot secondary air is supplied to the combustion
furnaces so that the fuel-air mixture and the secondary air blow
into the furnace. Accordingly, a flame is generated, and hence the
fuel-air mixture may be burned inside the furnace by the flame.
Then, a flue gas duct is connected to the upper portion of the
furnace, and the flue gas duct is equipped with a superheater, a
reheater, an economizer, and the like for collecting the heat of a
flue gas. Thus, steam may be produced by the heat exchange between
water and the flue gas produced by the combustion in the
furnace.
[0004] As such a pulverized-coal-combustion boiler or such a
combustion burner, for example, pulverized-coal-combustion boilers
or combustion burners disclosed in Patent Literatures below are
known.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: Japanese Laid-open Patent Publication
No. 08-135919
[0006] Patent Literature 2: Japanese Laid-open Patent Publication
No. 2006-189188
[0007] Patent Literature 3: Japanese Laid-open Patent Publication
No. 8-296815
[0008] Patent Literature 4: Japanese Laid-open Patent Publication
No. 9-203505
[0009] Patent Literature 5: Japanese Laid-open Patent Publication
No. 2006-057903
[0010] Patent Literature 6: Japanese Laid-open Patent Publication
No. 2008-145007
SUMMARY
Technical Problem
[0011] In the above-described conventional combustion burner, when
a fuel gas obtained by mixing pulverized coal with air collides
with a flame stabilizer, a separation of a flow occurs at a rear
end portion of the flame stabilizer, and hence it is difficult to
sufficiently exhibit the flame stabilization ability at the front
end portion of the flame stabilizer. Further, in the conventional
boiler, since the pulverized coal contains moisture or a volatile
content, operation parameters need to be adjusted based on the
operation output of the boiler. In this case, it is difficult to
directly set the operation parameters from the characteristics of
the coal.
[0012] It is an object of the invention to provide a combustion
burner, a solid-fuel-combustion burner, and a solid-fuel-combustion
boiler capable of realizing an appropriate flow of a fuel gas
obtained by mixing solid fuel with air.
[0013] Further, it is another object of the invention to provide a
boiler and a method for operating the boiler capable of improving
operation efficiency by appropriately burning solid fuel and a
volatile content contained in the solid fuel.
Solution to Problem
[0014] According to an aspect of the present invention, a
combustion burner includes: a fuel nozzle that is able to blow a
fuel gas obtained by mixing solid fuel with air; a secondary air
nozzle that is able to blow air from the outside of the fuel
nozzle; a flame stabilizer that is provided at a front end portion
of the fuel nozzle so as to be near an axis center side of the fuel
nozzle; and a rectification member that is provided between an
inner wall surface of the fuel nozzle and the flame stabilizer.
[0015] Accordingly, since a rectification member is provided
between the inner wall surface of the fuel nozzle and the flame
stabilizer, the flow of the fuel gas flowing through the fuel
nozzle is rectified by the rectification member, and the separation
of the flow at the rear end portion of the flame stabilizer is
suppressed. Also, since the flow velocity becomes substantially
uniform, the deposit of the solid fuel to the wall surface of the
fuel nozzle is suppressed. Thus, the appropriate flow of the fuel
gas may be realized.
[0016] Advantageously, in the combustion burner, the rectification
member is disposed so as to have a predetermined gap with respect
to the flame stabilizer.
[0017] Accordingly, since a predetermined gap is ensured between
the rectification member and the flame stabilizer, the flow of the
fuel gas flowing between the rectification member and the flame
stabilizer is rectified, and hence the flame stabilizing function
using the flame stabilizer may be sufficiently exhibited.
[0018] Advantageously, in the combustion burner, the rectification
member is provided so that a distance between the rectification
member and the flame stabilizer is substantially uniform in the
fuel gas flowing direction.
[0019] Accordingly, since the distance between the rectification
member and the flame stabilizer is substantially equal in the fuel
gas flowing direction by the rectification member, the flow
velocity of the fuel gas flowing between the rectification member
and the flame stabilizer becomes substantially uniform, and hence
the deposit of the solid fuel to the fuel nozzle or the attachment
of the solid fuel to the flame stabilizer may be suppressed.
Further, since the passage is not extremely narrowed, the blockage
of the passage may be prevented.
[0020] Advantageously, in the combustion burner, a widened portion
is provided at the downstream side of the flame stabilizer in the
fuel gas flowing direction and a tapered portion is provided at the
downstream side of the rectification member in the fuel gas flowing
direction.
[0021] Accordingly, since the front end portion of the flame
stabilizer is equipped with the widened portion, the flame may be
reliably realized. Then, since the front end portion of the
rectification member is equipped with the tapered portion, the
distance between the flame stabilizer and the rectification member
becomes substantially uniform in the fuel gas flowing
direction.
[0022] Advantageously, in the combustion burner, a widened portion
is provided at the downstream side of the flame stabilizer in the
fuel gas flowing direction, and the rectification member is
provided at a position where the rectification member does not face
the widened portion.
[0023] Accordingly, since the rectification member is provided at a
position where the rectification member does not face the widened
portion of the flame stabilizer, the fuel gas passage between the
widened portion of the flame stabilizer and the fuel nozzle is not
narrowed, and the flow velocity of the fuel gas becomes
substantially uniform. Accordingly, it is possible to suppress the
deposit of the solid fuel to the fuel nozzle or the attachment of
the solid fuel to the flame stabilizer.
[0024] Advantageously, in the combustion burner, the rectification
member is provided along the inner wall surface of the fuel
nozzle.
[0025] Accordingly, since the rectification member is provided in
the inner wall surface of the fuel nozzle, a separate attachment
member or the like is not needed. Thus, the assembling workability
may be improved and the manufacturing cost may be reduced.
[0026] Advantageously, in the combustion burner, the flame
stabilizer is formed in a structure in which a first flame
stabilizing member disposed in the horizontal direction and a
second flame stabilizing member disposed in the vertical direction
are disposed so as to intersect each other.
[0027] Accordingly, since the flame stabilizer is formed in a
structure in which the first flame stabilizing member intersects
the second flame stabilizing member, the sufficient flame
stabilizing function may be ensured.
[0028] Advantageously, in the combustion burner, the first flame
stabilizing member and the second flame stabilizing member
respectively include a plurality of flame stabilizing members, a
plurality of the first flame stabilizing members are disposed in
the vertical direction with a predetermined gap therebetween, a
plurality of the second flame stabilizing members are disposed in
the horizontal direction with a predetermined gap therebetween, and
the plurality of first flame stabilizing members and the plurality
of second flame stabilizing members are disposed so as to intersect
each other.
[0029] Accordingly, since the flame stabilizer is formed in a
double cross structure, the sufficient flame stabilizing function
may be ensured.
[0030] Advantageously, in the combustion burner, in any one of the
first flame stabilizing member and the second flame stabilizing
member, one side width is set to be larger than the other side
width.
[0031] Accordingly, when the width of the first flame stabilizing
member disposed in the horizontal direction increases, the flame
stabilizing function in the horizontal direction may be improved by
the first flame stabilizing member with a wide width. Further, when
the width of the second flame stabilizing member disposed in the
vertical direction increases, the flame stabilizing function may be
improved without the adverse influence of the second flame
stabilizing member when the direction of the nozzle swings up and
down for the steam temperature control or the like. This is because
of the following reasons. When the nozzle moves up and down, the
position of the flame stabilizing member with respect to the fuel
gas blowing position largely changes in the first flame stabilizing
member, but substantially does not change in the second flame
stabilizing member.
[0032] According to another aspect of the present invention, a
combustion burner includes: a fuel nozzle that is able to blow a
fuel gas obtained by mixing solid fuel with air; a secondary air
nozzle that is able to blow air from the outside of the fuel
nozzle; a flame stabilizer that is provided at a front end portion
of the fuel nozzle so as to be near an axis center side of the fuel
nozzle; and a guide member that guides the fuel gas flowing through
the fuel nozzle toward the axis center side of the fuel nozzle.
[0033] Accordingly, since the guide member is provided so as to
guide the fuel gas flowing through the fuel nozzle toward the axis
center side of the fuel nozzle, the fuel gas flowing through the
fuel nozzle is guided by the guide member toward the axis center
side of the fuel nozzle, and hence the appropriate flow of the fuel
gas may be realized. As a result, the inner flame stabilization
performance may be improved, and hence the NOx production amount
may be reduced.
[0034] Advantageously, in the combustion burner, the guide member
guides the fuel gas in a direction in which the fuel gas is
separated from the secondary air blown from the secondary air
nozzle.
[0035] Accordingly, the fuel gas is guided by the guide member in a
direction in which the fuel gas is separated from the secondary air
and the mixing of the fuel gas and the secondary air is suppressed,
and hence the outer peripheral portion of the combustion flame is
maintained at a low temperature. For this reason, the NOx
production amount caused by the mixing of the combustion gas and
the secondary air may be reduced.
[0036] Advantageously, in the combustion burner, the guide member
is disposed along an inner wall surface of the fuel nozzle.
[0037] Accordingly, since the guide member is disposed in the inner
wall surface of the fuel nozzle, the fuel gas flowing through the
fuel nozzle is effectively guided toward the axis center side of
the fuel nozzle, and hence the fuel gas may be guided in a
direction in which the fuel gas is separated from the secondary
air.
[0038] Advantageously, in the combustion burner, the guide member
is disposed at the front end portion of the fuel nozzle so as to
face the flame stabilizer.
[0039] Accordingly, since the guide member is disposed so as to
face the flame stabilizer, the inner flame stabilization
performance may be improved.
[0040] Advantageously, in the combustion burner, the guide member
is disposed at a position where the guide member faces the inner
wall surface of the fuel nozzle in the flame stabilizer.
[0041] Accordingly, the fuel gas flowing along the flame stabilizer
may be effectively guided by the guide member toward the front end
portion of the flame stabilizer so as to stabilize the flame.
[0042] Advantageously, in the combustion burner, the guide member
is disposed at the upstream side of the flame stabilizer in the
fuel gas flowing direction.
[0043] Accordingly, since the guide member is separated from the
flame stabilizer, the guide member does not degrade the flame
stabilizing function of the flame stabilizer.
[0044] Advantageously, in the combustion burner, the flame
stabilizer is formed in a structure in which two first flame
stabilizing members provided in the horizontal direction while
being parallel to each other in the vertical direction with a
predetermined gap therebetween and two second flame stabilizing
members provided in the vertical direction while being parallel to
each other in the horizontal direction with a predetermined gap
therebetween are disposed so as to intersect one another, and the
guide member is disposed at the outside of the intersection
position of the first flame stabilizing members and the second
flame stabilizing members.
[0045] Accordingly, since the flame stabilizer is formed in a
double cross structure, the sufficient flame stabilizing function
may be ensured, and the fuel gas flowing through the fuel nozzle
may be effectively guided by the guide member toward the axis
center side of the fuel nozzle.
[0046] Advantageously, in the combustion burner, the flame
stabilizer includes a widened portion formed at the downstream side
in the fuel gas flowing direction, and the guide member is disposed
so as to face the widened portion.
[0047] Accordingly, the sufficient flame stabilizing function may
be ensured.
[0048] Advantageously, in the combustion burner, the guide member
includes two flame stabilizing members that are provided in the
horizontal direction while being parallel to each other in the
vertical direction with a predetermined gap therebetween, and the
guide member is provided so that the front end portions of the
flame stabilizing members face the axis center side of the fuel
nozzle.
[0049] Accordingly, since the guide member is formed by the flame
stabilizing member, the structure may be simplified.
[0050] According to still another aspect of the present invention,
a solid-fuel-combustion burner that is used in the burner portion
of a solid-fuel-combustion boiler and inputs pulverized solid fuel
and air into a furnace, includes: a fuel burner that inputs
pulverized fuel and primary air into the furnace; and a secondary
air input port that ejects secondary air from the outer periphery
of the fuel burner. A cross type split member obtained by
intersecting a plurality of inner flame stabilization members in a
plurality of directions is disposed at a front side of a passage of
the fuel burner, and the width of the split member is different for
each direction.
[0051] According to such a solid-fuel-combustion burner, the
solid-fuel-combustion burner includes the fuel burner that inputs
the pulverized fuel and the primary air into the furnace and the
secondary air input port that ejects the secondary air from the
outer periphery of the fuel burner, the cross type split member
obtained by intersecting the plurality of inner flame stabilization
members in a plurality of directions is disposed at the front side
of the passage of the fuel burner, and the width of the split
member is different for each direction. For this reason, since the
split member provided near the center of the outlet opening divides
the passage of the pulverized coal and the air so as to disturb the
flow therein, and forms a recirculation zone at the front side of
the split member, the split member serves as an inner flame
stabilization mechanism. As a result, it is possible to suppress
the hot oxygen remaining zone formed in the outer periphery of the
flame.
[0052] In the above-described invention, the cross type split
member may be wide in the up and down direction. Thus, even when
the nozzle angle changes in the up and down direction, the
positional relation with respect to the splitter member hardly
changes.
[0053] In the above-described invention, the cross type split
member may be wide in the left and right direction. Thus, since the
splitter function in the horizontal direction is strengthened, the
direct interference with the secondary air input from the up and
down direction may be suppressed.
[0054] In the above-described invention, three or more cross type
split members are disposed in at least one of the left and right
direction and the up and down direction. Furthermore, the center
portions in at least one of the left and right direction and the up
and down direction may be wide. Thus, the inner ignition may be
strengthened while preventing the outer peripheral ignition.
[0055] According to still another aspect of the present invention,
a solid-fuel-combustion burner that is used in the burner portion
of a solid-fuel-combustion boiler, includes a fuel burner with an
inner flame stabilization function and a secondary air input port
without a flame stabilization function, and inputs pulverized solid
fuel and air into a furnace, includes: the fuel burner that inputs
pulverized fuel and primary air into a furnace; and the secondary
air input port that ejects secondary air from the outer periphery
of the fuel burner. A cross type split member obtained by
intersecting a plurality of members in a plurality of directions is
disposed at a front side of a passage of the fuel burner, and a
shielding member that reduces a passage sectional area is provided
in at least one position of the intersecting corners formed by the
intersection of the split members.
[0056] According to such a solid-fuel-combustion burner, the
solid-fuel-combustion burner includes the fuel burner that inputs
the pulverized fuel and the primary air into the furnace and the
secondary air input port that ejects the secondary air from the
outer periphery of the fuel burner, the cross type split member
obtained by intersecting the plurality of members in a plurality of
directions is disposed at the front side of the passage of the fuel
burner, and the shielding member that reduces the passage sectional
area is provided in at least one position of the intersection
corner formed by the intersection of the split members. For this
reason, the inner flame stabilizing function using the cross type
split member may be further strengthened.
[0057] In the above-described invention, the solid-fuel-combustion
boiler may be divided into the burner portion and the additional
air input unit so as to perform the low NOx combustion. Thus, the
reduction may be further strongly performed by the division of the
additional input air.
[0058] Advantageously, in the solid-fuel-combustion boiler, the
solid-fuel-combustion burner that inputs the pulverized fuel and
the air into the furnace is disposed at a corner or a wall surface
inside the furnace.
[0059] According to the solid-fuel-combustion boiler, since the
solid-fuel-combustion burner that inputs the pulverized fuel and
the air into the furnace is disposed at the corner or the wall
surface inside the furnace, the split member that is disposed near
the center of the outlet opening of the fuel burner and serves as
the inner flame stabilization mechanism divides the passage of the
pulverized fuel and the air so as to disturb the flow. As a result,
the mixture and the dispersion of the air are promoted to the
inside of the flame, and hence the ignition surface is further
finely divided. Accordingly, since the ignition position is near
the center of the flame, the unburned combustible content of the
fuel is reduced. That is, since oxygen easily enters the center
portion of the flame, the inner ignition is effectively performed,
and the reduction inside the flame promptly occurs. Thus, the NOx
production amount is reduced.
[0060] According to another aspect of the present invention, a
solid-fuel-combustion burner that is used in the burner portion of
a solid-fuel-combustion boiler and inputs pulverized solid fuel and
air into a furnace, includes: a fuel burner that inputs pulverized
fuel and primary air into the furnace; and a coal secondary port
that ejects secondary air from the outer periphery of the fuel
burner. A split member as an inner flame stabilization member is
disposed at a front side of a passage of the fuel burner, and a
part of an end portion adjacent to the coal secondary port at the
outer periphery of the split member is removed.
[0061] According to such a solid-fuel-combustion burner, the
solid-fuel-combustion burner includes the fuel burner that inputs
the pulverized fuel and the primary air into the furnace and the
coal secondary port that ejects the secondary air from the outer
periphery of the fuel burner, the split member as the inner flame
stabilization member is disposed at the front side of the passage
of the fuel burner, and a part of the end portion adjacent to the
coal secondary port at the outer periphery of the split member is
removed. For this reason, the split member that is provided near
the center of the outlet opening divides the passage of the
pulverized coal and the air so as to disturb the flow therein.
Further, since the split member forms a recirculation zone at the
front side of the split member, the split member serves as the
inner flame stabilization mechanism. As a result, the hot oxygen
remaining zone formed at the outer periphery of the flame may be
suppressed.
[0062] Particularly, in a zone in which the end portion of the
split member is removed, the ignition performed using the split
member as the ignition source may be suppressed. Furthermore, the
flame stabilizing function at the center portion side of the split
member as the inside of the flame may be effectively used.
[0063] Advantageously, in the solid-fuel-combustion burner, the
inner flame stabilization member is a cross type split member
obtained by intersecting a plurality of members in a plurality of
directions.
[0064] Advantageously, in the solid-fuel-combustion burner, a
plurality of split members of the inner flame stabilization member
are disposed in at least one direction.
[0065] In the above-described invention, the end portion of the
cross type split member in any one direction of a plurality of
directions may be removed. Thus, the inner ignition may be promoted
by reducing the ignition source at the end portion of the split
member. That is, in the cross type split member obtained by the
intersection of two directions of the up and down direction and the
left and right direction, any one of the end portions in the up and
down direction and the left and right direction may be removed.
[0066] Particularly, in a case of a turning combustion type, the
end portion of the split member in the up and down direction may be
removed. Thus, it is possible to prevent a zone with a high
temperature and a high oxygen concentration from being formed at
the upper and lower ends that may easily and directly interfere
with the secondary air.
[0067] In the above-described invention, three or more cross type
split members may be disposed in at least one of the up and down
direction and the left and right direction, and the end portions of
the cross type split members may be removed except for at least one
cross type split member disposed at the center portion in at least
one of the up and down direction and the left and right direction.
Thus, a structure is obtained in which the split member does not
exist in a zone that is supposed to contribute the outer peripheral
ignition the most.
[0068] In the above-described invention, the solid-fuel-combustion
boiler may be divided into the burner and the additional air input
unit so as to perform the low NOx combustion. Thus, the reduction
may be further strongly performed by the division of the additional
input air.
[0069] Advantageously, in the solid-fuel-combustion burner, the
solid-fuel-combustion burner that inputs the pulverized fuel and
the air into the furnace is disposed at a corner or a wall surface
inside the furnace.
[0070] According to such a solid-fuel-combustion boiler, since the
solid-fuel-combustion burner that inputs the pulverized fuel and
the air into the furnace is disposed in the corner or the wall
surface inside the furnace, the split member disposed near the
center of the outlet opening of the fuel burner and serving as the
inner flame stabilization mechanism divides the passage of the
pulverized fuel and the air so as to disturb the flow thereof. As a
result, the mixture and the dispersion of the air are promoted to
the inside of the flame, and hence the ignition surface is further
finely divided.
[0071] Accordingly, since the ignition position is near the center
of the flame, the unburned combustible content of the fuel is
reduced. That is, since oxygen easily enters the center portion of
the flame, the inner ignition is effectively performed, and the
reduction inside the flame is promptly occurs. Thus, the NOx
production amount is reduced. Particularly, in a zone in which the
end portion of the split member is removed, the ignition performed
using the split member as the ignition source may be suppressed.
Furthermore, the flame stabilizing function at the center portion
side of the split member as the inside of the flame may be
effectively used.
[0072] According to still another aspect of the present invention,
a boiler includes: a furnace that burns solid fuel and air; a heat
exchanger that collects heat by a heat exchange inside the furnace;
a fuel nozzle that is able to blow a fuel gas obtained by mixing
solid fuel with primary air into the furnace; a secondary air
nozzle that is able to blow secondary air from the outside of the
fuel nozzle to the furnace; an additional air nozzle that is able
to blow additional air to the upside of the fuel nozzle and the
secondary air nozzle in the furnace; an air amount adjusting device
that is able to adjust the amount of the air supplied to the fuel
nozzle, the secondary air nozzle, and the additional air nozzle;
and a control device that controls the air amount adjusting device
in response to a volatile content of the solid fuel.
[0073] Accordingly, since the control device controls the air
amount adjusting device in response to the volatile content of the
solid fuel so that the air amount adjusting device adjusts the
amount of the air supplied to the fuel nozzle, the secondary air
nozzle, and the additional air nozzle, the primary air amount, the
secondary air amount, and the additional air amount are adjusted in
response to the volatile content of the solid fuel. Accordingly,
the volatile content of the solid fuel may be appropriately burned
and the solid fuel may be appropriately burned. Thus, the
production of the NOx or the unburned combustible content is
suppressed, and hence the boiler operation efficiency may be
improved.
[0074] Advantageously, in the boiler, the control device controls
the air amount adjusting device in response to the volatile content
of the solid fuel so as to adjust a distribution of the total air
amount of the primary air and the secondary air and the air amount
of the additional air.
[0075] Accordingly, the total air amount of the primary air and the
secondary air is the air amount necessary for burning the volatile
content of the solid fuel, and the total air amount of the primary
air and the secondary air changes in response to the volatile
content of the solid fuel. Thus, the volatile content of the solid
fuel may be appropriately burned.
[0076] Advantageously, in the boiler, the furnace is equipped with
a tertiary air nozzle that is able to blow tertiary air from the
outside of the secondary air nozzle, and the control device
controls the air amount adjusting device in response to the
volatile content of the solid fuel so as to adjust a distribution
of the total air amount of the primary air and the secondary air
and the total air amount of the tertiary air and the additional
air.
[0077] Accordingly, since the total air amount of the primary air
and the secondary air changes, the volatile content of the solid
fuel may be appropriately burned.
[0078] Advantageously, in the boiler, the control device controls
the air amount adjusting device so that the primary air amount and
the additional air amount become a predetermined air amount, and
adjusts a distribution of the secondary air and the tertiary air in
response to the volatile content of the solid fuel.
[0079] Accordingly, since the primary air is the transportation air
for transporting the solid fuel and the additional air completely
burns the solid fuel so as to suppress the production of NOx, the
primary air and the additional air are set as the predetermined air
amounts, and the distribution of the secondary air and the tertiary
air is adjusted in response to the volatile content of the solid
fuel. Thus, the solid fuel and the volatile content thereof may be
appropriately burned while maintaining a predetermined fuel-air
ratio.
[0080] Advantageously, in the boiler, the control device increases
a distribution of the secondary air when the volatile content of
the solid fuel increases.
[0081] Accordingly, since the secondary air is the combustion air
mixed with the fuel gas so as to burn the solid fuel, the solid
fuel and the volatile content thereof may be appropriately burned
by increasing the distribution of the secondary air when the
volatile content of the solid fuel increases.
[0082] According to still another aspect of the present invention,
a method for operating a boiler including a furnace that burns
solid fuel and air, a heat exchanger that collects heat by a heat
exchange inside the furnace, a fuel nozzle that is able to blow a
fuel gas obtained by mixing solid fuel with primary air to the
furnace, a secondary air nozzle that is able to blow secondary air
from the outside of the fuel nozzle into the furnace, and an
additional air nozzle that is able to blow additional air to the
upside of the fuel nozzle and the secondary air nozzle in the
furnace. A distribution of the secondary air and the tertiary air
is adjusted in response to a volatile content of the solid
fuel.
[0083] Accordingly, since the distribution of the secondary air and
the tertiary air is adjusted in response to the volatile content of
the solid fuel, the volatile content of the solid fuel may be
appropriately burned and the solid fuel may be appropriately
burned. Thus, the production of the NOx or the unburned combustible
content is suppressed, and hence the boiler operation efficiency
may be improved.
[0084] Advantageously, in the method for operating the boiler, the
distribution of the secondary air increases when the volatile
content of the solid fuel increases.
[0085] Accordingly, since the secondary air is the combustion air
mixed with the fuel gas so as to burn the solid fuel, the solid
fuel and the volatile content thereof may be appropriately burned
by increasing the distribution of the secondary air when the
volatile content of the solid fuel increases.
Advantageous Effects of Invention
[0086] According to the combustion burner of the invention, since
the combustion burner includes: the fuel nozzle that is able to
blow the fuel gas obtained by mixing the solid fuel and the air;
the secondary air nozzle that is able to blow the air from the
outside of the fuel nozzle; the flame stabilizer that is provided
at the front end portion of the fuel nozzle so as to be near the
axis center side of the fuel nozzle; and the rectification member
that is provided between the inner wall surface of the fuel nozzle
and the flame stabilizer, the appropriate flow of the fuel gas may
be realized.
[0087] Further, according to the combustion burner of the
invention, since the combustion burner includes: the fuel nozzle
that is able to blow the fuel gas obtained by mixing the solid fuel
and the air; the secondary air nozzle that is able to blow the air
from the outside of the fuel nozzle; the flame stabilizer that is
provided at the front end portion of the fuel nozzle so as to be
near the axis center side of the fuel nozzle; and the guide member
that guides the fuel gas flowing through the fuel nozzle toward the
axis center side of the fuel nozzle, the appropriate flow of the
fuel gas may be realized, and hence the inner flame stabilization
performance may be improved.
[0088] Further, according to the solid-fuel-combustion burner and
the solid-fuel-combustion boiler of the invention, since the outlet
opening of the fuel burner is equipped with the split member
provided as the inner flame stabilization mechanism in a plurality
of directions, the passage of the pulverized fuel and the air may
be divided and disturbed near the center of the outlet opening of
the fuel burner in which the split members intersect each other,
and hence the ignition surface is further finely divided by the
split members. Accordingly, since the ignition position is disposed
near the center of the flame, the oxygen concentration at the
center thereof is relatively low. For this reason, the reduction
inside the flame is promptly performed, and hence the amount of NOx
finally discharged from the solid-fuel-combustion boiler is
reduced. Further, since the splitter is provided in a plurality of
directions, the inner air dispersion is promoted, and hence it is
possible to suppress the unburned combustible content caused by the
locally and extremely insufficient oxygen inside the flame.
[0089] That is, the hot oxygen remaining zone formed at the outer
periphery of the flame is suppressed, and hence the final NOx
production amount of NOx discharged from the additional air input
unit may be reduced. In other words, since the hot oxygen remaining
zone formed at the outer periphery of the flame is suppressed, the
NOx produced inside the flame generated by the pre-mixture
combustion is effectively reduced. Accordingly, it is possible to
obtain a remarkable advantage in which the final NOx amount
decreases due to a decrease in the NOx amount reaching the
additional air input unit and a decrease in the NOx amount produced
by the input of the additional air.
[0090] Further, according to the solid-fuel-combustion burner and
the solid-fuel-combustion boiler of the invention, since the outlet
opening of the fuel burner is equipped with the split member
provided as the inner flame stabilization mechanism in a plurality
of directions, the passage of the pulverized fuel and the air may
be divided and disturbed near the center of the outlet opening of
the fuel burner in which the split members intersect each other,
and hence the ignition surface is further finely divided by the
split members. Accordingly, since the ignition position is disposed
near the center of the flame, the oxygen concentration at the
center thereof is relatively low. For this reason, the reduction
inside the flame is promptly performed, and hence the amount of NOx
finally discharged from the solid-fuel-combustion boiler is
reduced. Further, since the splitter is provided in a plurality of
directions, the inner air dispersion is promoted, and hence it is
possible to suppress the unburned combustible content caused by the
locally and extremely insufficient oxygen inside the flame.
[0091] That is, the hot oxygen remaining zone formed at the outer
periphery of the flame is suppressed, and hence the final NOx
production amount of NOx discharged from the additional air input
unit may be reduced. In other words, since the hot oxygen remaining
zone formed at the outer periphery of the flame is suppressed, the
NOx produced inside the flame generated by the pre-mixture
combustion is effectively reduced. Accordingly, it is possible to
obtain a remarkable advantage in which the final NOx amount
decreases due to a decrease in the NOx amount reaching the
additional air input unit and a decrease in the NOx amount produced
by the input of the additional air.
[0092] Further, according to the boiler and the method for
operating the boiler of the invention, since the distribution of
the secondary air and the tertiary air and the additional air, and
the like is adjusted in response to the volatile content of the
solid fuel, it is possible to improve the operation efficiency by
appropriately burning the solid fuel and the volatile content
contained in the solid fuel.
BRIEF DESCRIPTION OF DRAWINGS
[0093] FIG. 1 is a front view illustrating a combustion burner
according to a first embodiment of the invention.
[0094] FIG. 2 is a cross-sectional view illustrating the combustion
burner of the first embodiment.
[0095] FIG. 3 is a cross-sectional view illustrating a modified
example of the combustion burner of the first embodiment.
[0096] FIG. 4 is a cross-sectional view illustrating a modified
example of the combustion burner of the first embodiment.
[0097] FIG. 5 is a front view illustrating a modified example of
the combustion burner of the first embodiment.
[0098] FIG. 6 is a cross-sectional view illustrating a modified
example of the combustion burner of the first embodiment.
[0099] FIG. 7 is a cross-sectional view illustrating a modified
example of the combustion burner of the first embodiment.
[0100] FIG. 8 is a front view illustrating a modified example of
the combustion burner of the first embodiment.
[0101] FIG. 9 is a schematic configuration diagram illustrating a
pulverized-coal-combustion boiler that employs the combustion
burner of the first embodiment.
[0102] FIG. 10 is a plan view illustrating a combustion burner of
the pulverized-coal-combustion boiler of the first embodiment.
[0103] FIG. 11 is a cross-sectional view illustrating a combustion
burner according to a second embodiment of the invention.
[0104] FIG. 12 is a cross-sectional view illustrating a combustion
burner according to a third embodiment of the invention.
[0105] FIG. 13 is a cross-sectional view illustrating a combustion
burner according to a fourth embodiment of the invention.
[0106] FIG. 14 is a cross-sectional view illustrating a combustion
burner according to a fifth embodiment of the invention.
[0107] FIG. 15 is a cross-sectional view illustrating a combustion
burner according to a sixth embodiment of the invention.
[0108] FIG. 16 is a front view illustrating a combustion burner
according to a seventh embodiment of the invention.
[0109] FIG. 17 is a cross-sectional view illustrating the
combustion burner of the seventh embodiment.
[0110] FIG. 18 is a schematic configuration diagram illustrating a
pulverized-coal-combustion boiler that employs the combustion
burner of the seventh embodiment.
[0111] FIG. 19 is a plan view illustrating a combustion burner of
the pulverized-coal-combustion boiler of the seventh
embodiment.
[0112] FIG. 20 is a cross-sectional view illustrating a combustion
burner according to an eighth embodiment of the invention.
[0113] FIG. 21 is a front view illustrating a combustion burner
according to a ninth embodiment of the invention.
[0114] FIG. 22 is a front view illustrating a combustion burner
according to a tenth embodiment of the invention.
[0115] FIG. 23 is a cross-sectional view illustrating a combustion
burner according to an eleventh embodiment of the invention.
[0116] FIG. 24 is a cross-sectional view illustrating a modified
example of the combustion burner of the eleventh embodiment.
[0117] FIGS. 25A and 25B are diagrams illustrating a twelfth
embodiment relating to a solid-fuel-combustion
(coal-fuel-combustion) burner according to the invention, where
FIG. 25A is a front view in which the solid-fuel-combustion burner
is seen from the inside of a furnace and FIG. 25B is a
cross-sectional view taken along the line A-A of the
solid-fuel-combustion burner illustrated in FIG. 25A (a
longitudinal sectional view of the solid-fuel-combustion
burner).
[0118] FIG. 26 is a diagram illustrating an air supply system which
supplies air to the solid-fuel-combustion burner of FIGS. 25A and
25B.
[0119] FIG. 27 is a longitudinal sectional view illustrating a
configuration example of a solid-fuel-combustion (coal-combustion)
boiler according to the invention.
[0120] FIG. 28 is a transverse (horizontal) cross-sectional view of
FIG. 24.
[0121] FIG. 29 is a diagram illustrating an outline of a
solid-fuel-combustion boiler which includes an additional air input
unit so as to input air through plural stages.
[0122] FIGS. 30A to 30D are diagrams illustrating a split member of
the solid-fuel-combustion burner illustrated in FIGS. 25A and 25B,
where FIG. 30A is a diagram illustrating an example of a
cross-sectional shape of the split member, FIG. 30B is a diagram
illustrating a first modified example of the cross-sectional shape,
FIG. 30C is a diagram illustrating a second modified example of the
cross-sectional shape, and FIG. 30D is a diagram illustrating a
third modified example of the cross-sectional shape.
[0123] FIGS. 31A and 31B are diagrams illustrating a fourteenth
embodiment relating to a solid-fuel-combustion
(coal-fuel-combustion) burner according to the invention, FIG. 31A
is a front view in which the solid-fuel-combustion burner is seen
from the inside of a furnace and FIG. 31B is a cross-sectional view
taken along the line B-B of the solid-fuel-combustion burner
illustrated in FIG. 31A (a longitudinal sectional view of the
solid-fuel-combustion burner).
[0124] FIG. 32A is a cross-sectional view taken along the line C-C
illustrating an example of one shape of a shielding member and FIG.
32B is a cross-sectional view illustrating an example of the other
shape of the shielding member illustrated in FIG. 32A.
[0125] FIGS. 33A and 33B are diagrams illustrating a fifteenth
embodiment relating to a solid-fuel-combustion
(coal-fuel-combustion) burner for a turning combustion boiler
according to the invention, where FIG. 33A is a front view in which
the solid-fuel-combustion burner is seen from the inside of a
furnace and FIG. 33B is a cross-sectional view taken along the line
A-A of the solid-fuel-combustion burner illustrated in FIG. 33A (a
longitudinal sectional view of the solid-fuel-combustion
burner).
[0126] FIG. 34 is a diagram illustrating an air supply system which
supplies air to the solid-fuel-combustion burner of FIGS. 33A and
33B.
[0127] FIG. 35 is a longitudinal sectional view illustrating a
configuration example of the solid-fuel-combustion boiler
(coal-combustion boiler) according to the invention.
[0128] FIG. 36 is a transverse (horizontal) cross-sectional view of
FIG. 35.
[0129] FIG. 37 is a diagram illustrating an outline of a
solid-fuel-combustion boiler which includes an additional air input
unit so as to input air through plural stages.
[0130] FIGS. 38A to 38D are diagrams illustrating a split member of
the solid-fuel-combustion burner illustrated in FIGS. 33A and 33B,
where FIG. 38A is a diagram illustrating an example of a
cross-sectional shape, FIG. 38B is a diagram illustrating a first
modified example of the cross-sectional shape, FIG. 38C is a
diagram illustrating a second modified example of the
cross-sectional shape, and
[0131] FIG. 38D is a diagram illustrating a third modified example
of the cross-sectional shape.
[0132] FIG. 39 is a schematic configuration diagram illustrating a
pulverized-coal-combustion boiler as a boiler according to a
seventeenth embodiment of the invention.
[0133] FIG. 40 is a plan view illustrating a combustion burner of
the pulverized-coal-combustion boiler of the seventeenth
embodiment.
[0134] FIG. 41 is a front view illustrating the combustion burner
of the seventeenth embodiment.
[0135] FIG. 42 is a cross-sectional view illustrating the
combustion burner of the seventeenth embodiment.
[0136] FIG. 43 is a graph illustrating a NOx production amount and
an unburned combustible content production amount with respect to
primary air and secondary air.
DESCRIPTION OF EMBODIMENTS
[0137] Hereinafter, preferred embodiments of a combustion burner, a
solid-fuel-combustion burner, a solid-fuel-combustion boiler, a
boiler, and a method for operating the boiler of the invention will
be described in detail with reference to the accompanying drawings.
Furthermore, the invention is not limited to the embodiments, and
also includes a case where the respective embodiments are combined
with one another when there are plural embodiments.
First Embodiment
[0138] As a combustion burner of a conventional
pulverized-coal-combustion boiler, the above-described combustion
burner disclosed in Patent Literature 1 is known. In the combustion
device disclosed in Patent Literature 1, the flame stabilizer is
provided between the center inside the pulverized coal ejecting
hole (primary passage) and the outer peripheral portion thereof so
that a pulverized coal condensed flow is made to collide with the
flame stabilizer. Accordingly, the low NOx combustion may be stably
performed in a broad load range.
[0139] However, in the conventional combustion device, when a fuel
gas of pulverized coal and air collides with the flame stabilizer,
the flow is divided at the rear end portion of the flame
stabilizer, and hence the flame stabilization ability at the front
end portion of the flame stabilizer may not be sufficiently
exhibited. Further, in the vicinity of the flame stabilizer of the
passage through which the fuel gas of pulverized coal and air
flows, the passage sectional area decreases due to the arrangement
of the flame stabilizer and the flow velocity of the fuel gas
becomes faster than that of the upstream side thereof. Then, the
flow velocity of the fuel gas becomes slow at the upstream side of
the flame stabilizer, so that the pulverized coal contained in the
fuel gas is deposited or attached to the lower portion of the
passage.
[0140] A first embodiment solves this problem, and provides a
combustion burner capable of realizing an appropriate flow of a
fuel gas obtained by mixing solid fuel and air.
[0141] FIG. 1 is a front view illustrating a combustion burner
according to the first embodiment of the invention, FIG. 2 is a
cross-sectional view illustrating the combustion burner of the
first embodiment, FIGS. 3 and 4 are cross-sectional views
illustrating modified examples of the combustion burner of the
first embodiment, FIG. 5 is a front view illustrating a modified
example of the combustion burner of the first embodiment, FIGS. 6
and 7 are cross-sectional views illustrating modified examples of
the combustion burner of the first embodiment, FIG. 8 is a front
view illustrating a modified example of the combustion burner of
the first embodiment, FIG. 9 is a schematic configuration diagram
illustrating a pulverized-coal-combustion boiler that employs the
combustion burner of the first embodiment, and FIG. 10 is a plan
view illustrating the combustion burner of the
pulverized-coal-combustion boiler of the first embodiment.
[0142] The pulverized-coal-combustion boiler that employs the
combustion burner of the first embodiment is a boiler which uses
pulverized coal obtained by milling coal as solid fuel, burns the
pulverized coal by a combustion burner, and collects heat generated
by the combustion.
[0143] In the first embodiment, as illustrated in FIG. 9, a
pulverized-coal-combustion boiler 10 is a conventional boiler, and
includes a furnace 11 and a combustion device 12. The furnace 11 is
formed in a hollow square cylindrical shape and is provided in the
vertical direction, and the combustion device 12 is provided in the
lower portion of the furnace wall forming the furnace 11.
[0144] The combustion device 12 includes plural combustion burners
21, 22, 23, 24, and 25 which are attached to the furnace wall. In
the embodiment, the combustion burners 21, 22, 23, 24, and 25 are
disposed as one set in the circumferential direction at four equal
intervals therebetween, and five sets, that is, five stages are
disposed in the vertical direction.
[0145] Then, the respective combustion burners 21, 22, 23, 24, and
25 are connected to coal pulverizers (mills) 31, 32, 33, 34, and 35
through pulverized coal supply pipes 26, 27, 28, 29, and 30.
Although not illustrated in the drawings, the coal pulverizers 31,
32, 33, 34, and 35 have a configuration in which milling tables are
supported in a rotational driving state with rotation axes along
the vertical direction inside a housing and plural milling rollers
are provided while facing the upper sides of the milling tables and
are supported so as to be rotatable along with the rotation of the
milling tables. Accordingly, when coal is input between plural
milling rollers and plural milling tables, the coal is milled into
a predetermined size therein. Thus, pulverized coal which is
classified by transportation air (primary air) may be supplied from
pulverized coal supply pipes 26, 27, 28, 29, and 30 to the
combustion burners 21, 22, 23, 24, and 25.
[0146] Further, in the furnace 11, wind boxes 36 are provided at
the attachment positions of the respective combustion burners 21,
22, 23, 24, and 25, where one end portion of an air duct 37 is
connected to the wind box 36 and an air blower 38 is attached to
the other end portion of the air duct 37. Accordingly, combustion
air (secondary air and tertiary air) sent by the air blower 38 may
be supplied from the air supply pipe 37 to the wind box 36, and may
be supplied from the wind box 36 to each of the combustion burners
21, 22, 23, 24, and 25.
[0147] For this reason, in the combustion device 12, the respective
combustion burners 21, 22, 23, 24, and 25 may blow a pulverized
fuel-air mixture (fuel gas) obtained by mixing pulverized coal and
primary air into the furnace 11 and may blow secondary air into the
furnace 11. Then, a flame may be formed by igniting the pulverized
fuel-air mixture through an ignition torch (not illustrated).
[0148] Furthermore, when generally activating the boiler, the
respective combustion burners 21, 22, 23, 24, and 25 form a flame
by ejecting oil fuel into the furnace 11.
[0149] A flue gas duct 40 is connected to the upper portion of the
furnace 11, and the flue gas duct 40 is equipped with superheaters
41 and 42, reheaters 43 and 44, and economizers 45, 46, and 47 as
convection heat transfer portions for collecting the heat of the
flue gas. Accordingly, a heat exchange is performed between water
and a flue gas that is produced by the combustion in the furnace
11.
[0150] The downstream side of the flue gas duct 40 is connected
with a flue gas pipe 48 into which the flue gas subjected to heat
exchange is discharged. An air heater 49 is provided between the
flue gas pipe 48 and the air duct 37, and a heat exchange is
performed between the air flowing through the air duct 37 and the
flue gas flowing through the flue gas pipe 48, so that the
combustion air flowing through the combustion burners 21, 22, 23,
24, and may increase in temperature.
[0151] Furthermore, although not illustrated in the drawings, the
flue gas pipe 48 is equipped with a denitration device, an
electronic precipitator, an inducing air blower, and a
desulfurization device, and the downstream end portion thereof is
equipped with a stack.
[0152] Accordingly, when the coal pulverizers 31, 32, 33, 34, and
35 are driven, pulverized coal produced therein is supplied along
with the transportation air to the combustion burners 21, 22, 23,
24, and 25 through pulverized coal supply pipes 26, 27, 28, 29, and
30. Further, the heated combustion air is supplied from the air
duct 37 to the respective combustion burners 21, 22, 23, 24, and 25
through the wind boxes 36. Then, the combustion burners 21, 22, 23,
24, and 25 blow the pulverized fuel-air mixture obtained by mixing
the pulverized coal and the transportation air to the furnace 11,
blow the combustion air to the furnace 11, and ignite the
pulverized fuel-air mixture and the air at this time so as to form
a flame. In the furnace 11, when the flame is generated by the
combustion of the pulverized fuel-air mixture and the combustion
air and the flame is generated at the lower portion inside the
furnace 11, the combustion gas (the flue gas) rises inside the
furnace 11 so as to be discharged to the flue gas duct 40.
[0153] Furthermore, the inside of the furnace 11 is maintained at
the reduction atmosphere in a manner such that the air supply
amount with respect to the pulverized coal supply amount becomes
smaller than the theoretical air amount. Then, when NOx produced by
the combustion of the pulverized coal is reduced in the furnace 11
and additional air is additionally supplied thereto, the
oxidization combustion of the pulverized coal is completed and
hence the production amount of NOx caused by the combustion of the
pulverized coal is reduced.
[0154] At this time, water supplied from a water feeding pump (not
illustrated) is preheated by the economizers 45, 46, and 47, is
supplied to a steam drum (not illustrated), and is heated while
being supplied to respective water pipes (not illustrated) of the
furnace wall so as to become saturated steam. Then, the saturated
steam is transported to a steam drum (not illustrated). Further,
the saturated steam of a steam drum (not illustrated) is introduced
into the superheaters 41 and 42 and is superheated by the
combustion gas. The superheated steam produced by the superheaters
41 and 42 is supplied to a power generation plant (not illustrated)
(for example, a turbine or the like). Further, the steam which is
extracted during the expanding process in the turbine is introduced
into the reheaters 43 and 44, is superheated again, and is returned
to the turbine. Furthermore, the furnace 11 of a drum type (steam
drum) has been described, but the invention is not limited to the
structure.
[0155] Subsequently, a harmful substance such as NOx is removed
from the flue gas which passes through the economizers 45, 46, and
47 of the flue gas duct 40 by a catalyst of a denitration device
(not illustrated) in the flue gas pipe 48, a particulate substance
is removed therefrom by the electronic precipitator, and a sulfur
content is removed therefrom by the desulfurization device. Then,
the flue gas is discharged to the atmosphere through the stack.
[0156] Here, the combustion device 12 will be described in detail,
but since the respective combustion burners 21, 22, 23, 24, and 25
constituting the combustion device 12 have substantially the same
configuration, only the combustion burner 21 that is positioned at
the uppermost stage will be described.
[0157] As illustrated in FIG. 10, the combustion burner 21 includes
the combustion burners 21a, 21b, 21c, and 21d which are provided at
four wall surfaces of the furnace 11. The respective combustion
burners 21a, 21b, 21c, and 21d are connected with respective branch
pipes 26a, 26b, 26c, and 26d which are branched from a pulverized
coal supply pipe 26, and are connected with respective branch pipes
37a, 37b, 37c, and 37d branched from the air duct 37.
[0158] Accordingly, the respective combustion burners 21a, 21b,
21c, and 21d which are positioned at the respective wall surfaces
of the furnace 11 blow the pulverized fuel-air mixture obtained by
mixing the pulverized coal and the transportation air to the
furnace 11 and blow the combustion air to the outside of the
pulverized fuel-air mixture. Then, the pulverized fuel-air mixture
is ignited from the respective combustion burners 21a, 21b, 21c,
and 21d, so that four flames F1, F2, F3, and F4 may be formed. The
flames F1, F2, F3, and F4 become a flame swirl flow that turns in
the counter-clockwise direction when viewed from the upside of the
furnace 11 (in FIG. 10).
[0159] As illustrated in FIGS. 1 and 2, in the combustion burner 21
(21a, 21b, 21c, and 21d) with such a configuration, the combustion
burner is equipped with a fuel nozzle 51, a secondary air nozzle
52, and a tertiary air nozzle 53 which are provided from the center
side thereof and is equipped with a flame stabilizer 54. The fuel
nozzle 51 may blow the fuel gas (the pulverized fuel-air mixture)
obtained by mixing the pulverized coal (the solid fuel) with the
transportation air (the primary air). The secondary air nozzle 52
is disposed at the outside of the first nozzle 51 and may blow the
combustion air (the secondary air) to the outer peripheral side of
the fuel gas ejected from the fuel nozzle 51. The tertiary air
nozzle 53 is disposed at the outside of the secondary air nozzle 52
and may blow the tertiary air to the outer peripheral side of the
secondary air ejected from the secondary air nozzle 52.
[0160] Further, the flame stabilizer 54 is disposed inside the fuel
nozzle 51 so as to be positioned at the downstream side of the fuel
gas blowing direction and near the axis center, and serves to
ignite and stabilize the fuel gas. The flame stabilizer 54 is
formed in a so-called double cross split structure in which first
flame stabilizing members 61 and 62 following the horizontal
direction and second flame stabilizing members 63 and 64 following
the vertical direction (the up and down direction) are disposed in
a cross shape. Then, the respective first flame stabilizing members
61 and 62 include flat portions 61a and 62a each formed in a flat
plate shape having a uniform thickness and widened portions 61b and
62b integrally formed with the front end portions of the flat
portions 61a and 62a (the downstream end portions in the fuel gas
flowing direction). Each cross-section of the widened portions 61b
and 62b is formed in an isosceles triangular shape, each width of
the widened portions is widened toward the downstream side in the
fuel gas flowing direction, and each front end thereof is formed as
a plane perpendicular to the fuel gas flowing direction.
Furthermore, although not illustrated in the drawings, the
respective second flame stabilizing members 63 and 64 also have the
same structure.
[0161] For this reason, each of the fuel nozzle 51 and the
secondary air nozzle 52 has an elongated tubular shape, the fuel
nozzle 51 includes a rectangular opening portion 51a, and the
secondary air nozzle 52 includes a rectangular annular opening
portion 52a. Thus, the fuel nozzle 51 and the secondary air nozzle
52 are formed as a double tube structure. The tertiary air nozzle
53 is disposed as a double tube structure at the outside of the
fuel nozzle 51 and the secondary air nozzle 52, and includes a
rectangular annular opening portion 53a. As a result, the opening
portion 52a of the secondary air nozzle 52 is disposed at the
outside of the opening portion 51a of the fuel nozzle 51, and the
opening portion 53a of the tertiary air nozzle 53 is disposed at
the outside of the opening portion 52a of the secondary air nozzle
52. Furthermore, the tertiary air nozzle 53 may not be disposed as
a double tube structure, and the tertiary air nozzle may be
obtained by separately disposing plural nozzles at the outer
peripheral side of the secondary air nozzle 52.
[0162] In the nozzles 51, 52, and 53, the opening portions 51a,
52a, and 53a are disposed so as to be flush with one another.
Further, the flame stabilizer 54 is supported by the inner wall
surface of the fuel nozzle 51 or a plate member (not illustrated)
from the upstream side of the passage through which the fuel gas
flows. Further, since plural flame stabilizing members 61, 62, 63,
and 64 are disposed as the flame stabilizer 54 inside the fuel
nozzle 51, the fuel gas passage is divided into nine segments.
Then, in the flame stabilizer 54, the widened portions 61b and 62b
of which the widths are wide are positioned at the front end
portions thereof, and the front end surfaces of the widened
portions 61b and 62b are evenly disposed so as to be flush with the
opening portion 51a.
[0163] Further, in the combustion burner 21 of the first
embodiment, a rectification member 55 is provided between the inner
wall surface of the fuel nozzle 51 and the flame stabilizer 54. The
rectification member 55 is disposed so as to have a predetermined
gap with respect to the inner wall surface of the fuel nozzle 51
and have a predetermined gap with respect to the flame stabilizer
54.
[0164] That is, the rectification member 55 is formed in a
structure in which first rectification members 65 and 66 following
the horizontal direction and second rectification members 67 and 68
following the vertical direction (the up and down direction) are
disposed so as to form a frame shape. That is, the first
rectification member 65 is positioned between the upper wall of the
fuel nozzle 51 and the first flame stabilizing member 61, and the
first rectification member 66 is positioned between the lower wall
of the fuel nozzle 51 and the first flame stabilizing member 62.
Further, the second rectification member 67 is positioned between
the side wall (in FIG. 1, the left wall) of the fuel nozzle 51 and
the second flame stabilizing member 63, and the second
rectification member 68 is positioned between the side wall (in
FIG. 1, the right wall) of the fuel nozzle 51 and the second flame
stabilizing member 64.
[0165] Then, the respective first rectification members 65 and 66
include flat portions 65a and 66a which are formed in a flat plate
shape having a uniform thickness and tapered portions 65b and 66b
which are integrally formed with the front end portions of the flat
portions 65a and 66a (the downstream end portions in the fuel gas
flowing direction). Each cross-section of the tapered portions 65b
and 66b is formed in an isosceles triangular shape, each width of
the tapered portions is narrowed toward the downstream side in the
fuel gas flowing direction, and each front end thereof becomes an
acute angle. Furthermore, although not illustrated in the drawings,
the respective second rectification members 67 and 68 also have the
same structure.
[0166] In this case, the respective flame stabilizing members 61,
62, 63, and 64 and the respective rectification members 65, 66, 67,
and 68 have substantially the same length in the fuel gas flowing
direction, and are disposed so as to face one another in a
direction perpendicular to the fuel gas flowing direction.
Furthermore, in the respective flame stabilizing members 61, 62,
63, and 64 and the respective rectification members 65, 66, 67, and
68, the widened portions 61b and 62b and the tapered portions 65b
and 66b also have substantially the same length in the fuel gas
flowing direction, and are disposed so as to face one another in a
direction perpendicular to the fuel gas flowing direction.
[0167] Since the flame stabilizer 54 and the rectification member
55 are formed in a shape equipped with the widened portions 61b and
62b and the tapered portions 65b and 66b, the distance between the
flame stabilizer 54 and the rectification member 55 in the fuel gas
flowing direction is substantially equal in the fuel gas flowing
direction.
[0168] Accordingly, in the combustion burner 21, the fuel gas
obtained by mixing the pulverized coal with the primary air blows
from the opening portion 51a of the fuel nozzle 51 into the
furnace, the secondary air at the outside thereof blows from the
opening portion 52a of the secondary air nozzle 52 into the
furnace, and the tertiary air at the outside thereof blows from the
opening portion 53a of the tertiary air nozzle 53 into the furnace.
At this time, the fuel gas is divided by the flame stabilizer 54 at
the opening portion 51a of the fuel nozzle 51, is ignited, and is
burned so as to become a combustion gas. Further, since the
secondary air blows to the outer periphery of the fuel gas, the
combustion of the fuel gas is promoted. Further, since the tertiary
air blows to the outer periphery of the combustion flame, the
combustion may be optimally performed by adjusting the ratio
between the secondary air and the tertiary air.
[0169] Then, since the flame stabilizer 54 is formed in a split
shape in the combustion burner 21, the fuel gas is divided by the
flame stabilizer 54 at the opening portion 51a of the fuel nozzle
51. At this time, the flame stabilizer 54 is disposed at the center
zone of the opening portion 51a of the fuel nozzle 51, and the fuel
gas is ignited and stabilized at the center zone. Thus, the inner
flame stabilization (the flame stabilization at the center zone of
the opening portion 51a of the fuel nozzle 51) of the combustion
flame is realized.
[0170] For this reason, compared to the configuration in which the
outer flame stabilization of the combustion flame is performed, the
temperature of the outer peripheral portion of the combustion flame
becomes low, and hence the temperature of the outer peripheral
portion of the combustion flame under the high oxygen atmosphere by
the secondary air may become low. Thus, the NOx production amount
at the outer peripheral portion of the combustion flame is
reduced.
[0171] Further, since the combustion burner 21 employs a
configuration in which the inner flame stabilization is performed,
it is desirable to supply the fuel gas and the combustion air (the
secondary air and the tertiary air) as a straight flow. That is, it
is desirable that the fuel nozzle 51 have a structure in which the
secondary air nozzle 52 and the tertiary air nozzle 53 supply the
fuel gas, the secondary air, and the tertiary air as a straight
flow instead of a swirl flow. Since the fuel gas, the secondary
air, and the tertiary air are ejected as the straight flow so as to
form the combustion flame, the circulation of the gas inside the
combustion flame is suppressed in the configuration in which the
inner flame stabilization of the combustion flame is performed.
Accordingly, the outer peripheral portion of the combustion flame
is maintained in a low temperature, and the NOx production amount
caused by the mixture with the secondary air is reduced.
[0172] Further, in the combustion burner 21, the rectification
member 55 is disposed between the fuel nozzle 51 and the flame
stabilizer 54 so as to have a predetermined gap therebetween. For
this reason, since the fuel gas particularly flowing between the
flame stabilizer 54 and the rectification member 55 is rectified,
the division of the fuel gas does not occur at the rear end portion
of the flame stabilizer 54, and the fuel gas flow directed to the
front end portion is formed. For this reason, the flame stabilizer
54 may ensure a sufficient flame stabilization ability at the front
end portion thereof.
[0173] Further, since the front end portion of the flame stabilizer
54 is equipped with the widened portions 61b and 62b and the front
end portion of the rectification member 55 is equipped with the
tapered portions 65b and 66b, the passage which is formed between
the flame stabilizer 54 and the rectification member 55 has
substantially the same passage sectional area in the longitudinal
direction. Thus, the flow velocity of the fuel gas flowing through
the passage becomes uniform, and the flow velocity of the fuel gas
decreases on the whole. Accordingly, the flame stabilizer 54 may
ensure a sufficient flame stabilization ability at the front end
portion thereof. Further, in the pulverized-coal-combustion boiler,
the steam temperature or the flue gas characteristics needs to be
adjusted, and even at this time, the inner flame stabilization may
be ensured by the rectification member 55.
[0174] Furthermore, in the combustion burner 21, the configurations
of the flame stabilizer 54 and the rectification member 55 are not
limited to those of the above-described embodiment.
[0175] For example, as illustrated in FIG. 3, the combustion burner
21 is equipped with the fuel nozzle 51, the secondary air nozzle
52, and the tertiary air nozzle 53 which are provided from the
center side of the combustion burner, and is equipped with a flame
stabilizer 71. The flame stabilizer 71 is disposed inside the fuel
nozzle 51 so as to be positioned at the downstream side in the fuel
gas blowing direction and near the axis center, and serves to
ignite and stabilize the fuel gas. The flame stabilizer 71 is
formed in a so-called double cross split structure in which first
flame stabilizing members 72 and 73 following the horizontal
direction and second flame stabilizing members (not illustrated)
following the vertical direction are disposed in a cross shape.
Then, each cross-section of the first flame stabilizing members 72
and 73 is formed in an isosceles triangular shape, each width of
the first flame stabilizing members is widened toward the
downstream side in the fuel gas flowing direction, and each front
end thereof is formed as a plane perpendicular to the fuel gas
flowing direction. Furthermore, the respective second flame
stabilizing members also have the same structure.
[0176] Accordingly, since the fuel gas is divided by the flame
stabilizer 71 at the opening portion 51a of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, and the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air. Thus, the NOx production amount
in the outer peripheral portion of the combustion flame is reduced.
Further, at this time, since the fuel gas flowing between the
rectification member 55 and the flame stabilizer 71 is rectified by
the rectification member, the separation of the fuel gas
disappears. Further, the flow velocity of the fuel gas flowing
therethrough becomes uniform, and the flow velocity thereof is
reduced. For this reason, the flame stabilizer 71 may ensure a
sufficient flame stabilization ability at the front end portion
thereof.
[0177] Further, as illustrated in FIG. 4, the combustion burner 21
is equipped with the fuel nozzle 51, the secondary air nozzle 52,
and the tertiary air nozzle 53 which are provided from the center
side of the combustion burner, and is equipped with the flame
stabilizer 54 Then, a rectification member 75 is provided between
the inner wall surface of the fuel nozzle 51 and the flame
stabilizer 54. The rectification member 75 is disposed so as to
have a predetermined gap with respect to the inner wall surface of
the fuel nozzle 51 and have a predetermined gap with respect to the
flame stabilizer 54. That is, the rectification member 75 is formed
in a structure in which first rectification members 76 and 77
following the horizontal direction and second rectification members
(not illustrated) following the vertical direction (the up and down
direction) are disposed so as to form a frame shape. Then, each of
the first rectification members 76 and 77 is formed in a flat plate
shape of which the thickness is uniform. Furthermore, the
respective second rectification members also have the same
structure.
[0178] In this case, the lengths of the respective rectification
members 76 and 77 are slightly shorter than those of the respective
flame stabilizing members 61 and 62 in the fuel gas flowing
direction, and the respective rectification members and the
respective flame stabilizing members are disposed so as to face one
another in a direction perpendicular to the fuel gas flowing
direction. That is, the flat portions 61a and 62a of the respective
flame stabilizing members 61 and 62 and the respective
rectification members 76 and 77 have substantially the same length
in the fuel gas flowing direction.
[0179] Since the flame stabilizer 54 and the rectification member
75 are formed in a shape equipped with the widened portions 61b and
62b, the distance between the flame stabilizer 54 and the
rectification member 75 in a direction perpendicular to the fuel
gas flowing direction is substantially equal in the fuel gas
flowing direction. Then, in the flame stabilizer 54, the widened
portions 61b and 62b are provided at the downstream side in the
fuel gas flowing direction, and the rectification member 75 is
provided at a position where the rectification member does not face
the widened portions 61b and 62b.
[0180] Accordingly, since the fuel gas is divided by the flame
stabilizer 54 at the opening portion of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, and the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air. Thus, the NOx production amount
of the outer peripheral portion of the combustion flame is reduced.
Further, at this time, since the fuel gas flowing between the
rectification member 75 and the flame stabilizer 54 is rectified by
the rectification member, the separation of the fuel gas
disappears. Further, the flow velocity of the fuel gas flowing
therethrough becomes uniform, and the flow velocity thereof is
reduced. For this reason, the flame stabilizer 54 may ensure the
sufficient flame stabilization ability at the front end portion
thereof.
[0181] Further, as illustrated in FIG. 5, the combustion burner 21
is equipped with the fuel nozzle 51, the secondary air nozzle 52,
and the tertiary air nozzle 53, and is equipped with a flame
stabilizer 81. Then, a rectification member 55 is provided between
the inner wall surface of the fuel nozzle 51 and the flame
stabilizer 81. The flame stabilizer 81 is disposed inside the fuel
nozzle 51 so as to be positioned at the downstream side in the fuel
gas blowing direction and near the axis center, and serves to
ignite and stabilize the fuel gas. The flame stabilizer 81 is
formed in a so-called double cross split structure in which first
flame stabilizing members 82 and 83 following the horizontal
direction and second flame stabilizing members 84 and 85 following
the vertical direction are disposed in a cross shape. Then, the
widths of the first flame stabilizing members 82 and 83 are set to
be larger than those of the second flame stabilizing members 84 and
85.
[0182] Accordingly, since the fuel gas is divided by the flame
stabilizer 81 at the opening portion 51a of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, and the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air. Thus, the NOx production amount
in the outer peripheral portion of the combustion flame is reduced.
In this case, since the widths of the first flame stabilizing
members 82 and 83 are larger than those of the second flame
stabilizing members 84 and 85, the first flame stabilizing members
82 and 83 have the higher flame stabilizing abilities than those of
the second flame stabilizing members 84 and 85. Since the burner 21
of the embodiment is of a turning combustion type and the air is
supplied from the upper and lower sides of the fuel gas, it is
effective to ensure a high flame stabilization ability in the
horizontal direction for the inner flame stabilization.
[0183] Here, since the widths of the first flame stabilizing
members 82 and 83 following the horizontal direction are set to be
larger than those of the second flame stabilizing members 84 and 85
following the vertical direction, it is possible to improve the
flame stabilizing function in the horizontal direction by the first
flame stabilizing members 82 and 83 having wide widths. Meanwhile,
the widths of the second flame stabilizing members 84 and 85
following the vertical direction may be set to be larger than those
of the first flame stabilizing members 82 and 83 following the
horizontal direction. In this case, it is possible to improve the
flame stabilizing function without the adverse influence of the
second flame stabilizing members 84 and 85 when the direction of
the fuel nozzle 51 swings up and down for the steam temperature
control or the like. This is because of the following reasons. When
the fuel nozzle 51 moves up and down, the position of the flame
stabilizing member with respect to the fuel gas blowing position
largely changes in the first flame stabilizing members 82 and 83,
but substantially does not change in the second flame stabilizing
members 84 and 85.
[0184] Further, as illustrated in FIG. 6, the combustion burner 21
is equipped with the fuel nozzle 51, the secondary air nozzle 52,
and the tertiary air nozzle 53 which are provided from the center
side of the combustion burner, and is equipped with a flame
stabilizer 91. The flame stabilizer 91 is disposed inside the fuel
nozzle 51 so as to be positioned at the downstream side in the fuel
gas blowing direction and near the axis center, and serves to
ignite and stabilize the fuel gas. The flame stabilizer 91 is
formed in a so-called double cross split structure in which first
flame stabilizing members 92 and 93 following the horizontal
direction and second flame stabilizing members (not illustrated)
following the vertical direction are disposed in a cross shape.
Then, the first flame stabilizing members 92 and 93 include flat
portions 92a and 93a, widened portions 92b and 93b, and tapered
portions 92c and 93c, and the tapered portions 92c and 93c are
provided in the rear end portion thereof so that the widths thereof
are narrowed toward the upstream side in the fuel gas flowing
direction. Furthermore, the respective second flame stabilizing
members also have the same structure.
[0185] Then, a rectification member 95 is provided between the
inner wall surface of the fuel nozzle 51 and the flame stabilizer
91. The rectification member 95 is disposed so as to have a
predetermined gap with respect to the inner wall surface of the
fuel nozzle 51 and have a predetermined gap with respect to the
flame stabilizer 91. That is, the rectification member 95 is formed
in a structure in which first rectification members 96 and 97
following the horizontal direction and second rectification members
(not illustrated) following the vertical direction (the up and down
direction) are disposed so as to form a frame shape. Then, the
respective first rectification members 96 and 97 include flat
portions 96a and 97a, tapered portions 96b and 97b, and tapered
portions 96c and 97c, and the tapered portions 96c and 97c are
provided in the rear end portion so that the widths thereof are
narrowed toward the upstream side in the fuel gas flowing
direction. Furthermore, the respective second rectification members
also have the same structure.
[0186] Accordingly, since the fuel gas is divided by the flame
stabilizer 91 at the opening portion 51a of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, and the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air. Thus, the NOx production amount
in the outer peripheral portion of the combustion flame is reduced.
Further, at this time, since the fuel gas flowing between the
rectification member 95 and the flame stabilizer 91 is rectified by
the rectification member, the separation of the fuel gas
disappears. Further, the flow velocity of the fuel gas flowing
therethrough becomes uniform, and the flow velocity thereof is
reduced. For this reason, the flame stabilizer 91 may ensure a
sufficient flame stabilization ability at the front end portion
thereof. Further, since the flame stabilizer 91 and the
rectification member 95 are equipped with the tapered portions 92c,
93c, 96c, and 97c, the fuel gas smoothly flows along the flame
stabilizer 91 or the rectification member 95, and hence the
division thereof is suppressed
[0187] Further, as illustrated in FIG. 7, the combustion burner 21
is equipped with the fuel nozzle 51, the secondary air nozzle 52,
and the tertiary air nozzle 53 which are provided from the center
side of the combustion burner, and is equipped with the flame
stabilizer 54. Then, a rectification member 101 is provided between
the inner wall surface of the fuel nozzle 51 and the flame
stabilizer 54. The rectification member 101 is disposed so as to
have a predetermined gap with respect to the inner wall surface of
the fuel nozzle 51 and have a predetermined gap with respect to the
flame stabilizer 54. That is, the rectification member 101 is
formed in a structure in which first rectification members 102 and
103 following the horizontal direction and second rectification
members (not illustrated) following the vertical direction (the up
and down direction) are disposed so as to form a frame shape. Then,
the respective first rectification members 102 and 103 include flat
portions 102a and 103a which are formed in a flat plate shape
having a uniform thickness and widened portions 102b and 103b which
are integrally formed with the front end portions (the downstream
end portions in the fuel gas flowing direction). Furthermore, the
respective second rectification members also have the same
structure.
[0188] In this case, the lengths of the respective rectification
members 102 and 103 are slightly shorter than those of the
respective flame stabilizing members 61 and 62 in the fuel gas
flowing direction, and the respective rectification members and the
respective flame stabilizing members are disposed so as to face one
another in a direction perpendicular to the fuel gas flowing
direction. That is, the flat portions 61a and 62a of the respective
flame stabilizing members 61 and 62 and the respective
rectification members 102 and 103 have substantially the same
length in the fuel gas flowing direction.
[0189] Accordingly, since the fuel gas is divided by the flame
stabilizer 54 at the opening portion of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, the temperature of the outer peripheral portion
of the combustion flame under a high oxygen atmosphere becomes low
by the secondary air, and the NOx production amount in the outer
peripheral portion of the combustion flame is reduced. Further, at
this time, since the fuel gas flowing between the rectification
member 101 and the flame stabilizer 54 is rectified by the
rectification member, the separation of the fuel gas disappears.
Further, the flow velocity of the fuel gas flowing therethrough
becomes uniform, and the flow velocity thereof is reduced. Thus,
the flame stabilizer 54 may ensure a sufficient flame stabilization
ability at the front end portion thereof. Further, since the
rectification member 101 is shorter than the flame stabilizer 54,
even when the widened portions 102b and 103b are provided at the
front end portions thereof so as to have a flame stabilizing
function, the flame stabilization ability may be improved without
extremely narrowing the passage sectional area of the fuel nozzle
51, and hence even a flame-resistant fuel may be stably burned.
[0190] Further, as illustrated in FIG. 8, the combustion burner 21
is equipped with a fuel nozzle 111, a secondary air nozzle 112, and
a tertiary air nozzle 113 which are provided from the center side
of the combustion burner, and is equipped with a flame stabilizer
114. Then, a rectification member 115 is provided between the inner
wall surface of the fuel nozzle 111 and the flame stabilizer 114.
In this case, the fuel nozzle 111 includes a circular opening
portion, and the secondary air nozzle 112 and the tertiary air
nozzle 113 also have the same cylindrical shape. Such a
configuration is particularly applied to a configuration in which
the combustion burner 21 is disposed in an opposing manner.
[0191] The flame stabilizer 114 is disposed inside the fuel nozzle
111 so as to be positioned at the downstream side in the fuel gas
blowing direction and near the axis center, and serves to ignite
and stabilize the fuel gas. The flame stabilizer 114 is disposed so
that two flame stabilizing members following the horizontal
direction intersect two flame stabilizing members following the
vertical direction. Further, the rectification member 115 is
disposed so as to have a predetermined gap with respect to the
inner wall surface of the fuel nozzle 111 and have a predetermined
gap with respect to the flame stabilizer 114. That is, the
rectification member 115 is formed in a structure in which two
rectification members following the horizontal direction and two
rectification members following the vertical direction are disposed
so as to form a frame shape.
[0192] Accordingly, since the fuel gas is divided by the flame
stabilizer 114 at the opening portion of the fuel nozzle 111, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, the temperature of the outer peripheral portion
of the combustion flame under a high oxygen atmosphere becomes low
by the secondary air, and the NOx production amount in the outer
peripheral portion of the combustion flame is reduced. Further, at
this time, since the fuel gas flowing between the rectification
member 115 and the flame stabilizer 114 is rectified by the
rectification member, the separation of the fuel gas disappears.
Further, the flow velocity of the fuel gas flowing therethrough
becomes uniform, and the flow velocity thereof is reduced. Thus,
the flame stabilizer 114 may ensure a sufficient flame
stabilization ability at the front end portion thereof.
[0193] In this way, the combustion burner of the first embodiment
includes the fuel nozzle 51 which may blow the fuel gas obtained by
mixing the pulverized coal with the primary air and the secondary
air nozzle 52 which may blow the secondary air from the outside of
the fuel nozzle 51, the flame stabilizer 54 is provided at the
front end portion of the fuel nozzle 51 so as to be near the axis
center, and the rectification member 55 is provided between the
inner wall surface of the fuel nozzle 51 and the flame stabilizer
54.
[0194] Accordingly, since the rectification member 55 is provided
between the inner wall surface of the fuel nozzle 51 and the flame
stabilizer 54, the flow of the fuel gas flowing through the fuel
nozzle 51 is rectified by the rectification member 55, and hence
the division of the flow of the fuel gas at the rear end portion of
the flame stabilizer 54 is suppressed. Also, since the flow
velocity becomes substantially uniform, the deposit (or the
attachment) of the pulverized coal fuel to the inner wall surface
of the fuel nozzle 51 is suppressed. Thus, the appropriate flow of
the fuel gas may be realized.
[0195] Further, in the combustion burner of the first embodiment,
the rectification member 55 is disposed so as to have a
predetermined gap with respect to the flame stabilizer 54.
Accordingly, since a predetermined gap is ensured between the
rectification member 55 and the flame stabilizer 54, the flow of
the fuel gas flowing between the rectification member 55 and the
flame stabilizer 54 is rectified, and the fuel gas is appropriately
introduced into the flame stabilizer 54. Thus, the flame
stabilizing function may be sufficiently exhibited by the flame
stabilizer 54.
[0196] Further, in the combustion burner of the first embodiment,
the distance between the flame stabilizer 54 and the rectification
member 55 in the fuel gas flowing direction becomes substantially
uniform by the rectification member 55. Accordingly, since the
distance between the rectification member 55 and the flame
stabilizer 54 in the fuel gas flowing direction becomes
substantially uniform by the rectification member, the flow
velocity of the fuel gas flowing between the rectification member
55 and the flame stabilizer 54 becomes substantially uniform, and
hence the deposit of the pulverized coal fuel of the fuel nozzle 51
or the attachment of the pulverized coal fuel to the flame
stabilizer 54 may be suppressed.
[0197] Further, in the combustion burner of the first embodiment,
the widened portions 61b and 62b are provided at the downstream
side in the fuel gas flowing direction of the flame stabilizer 54,
and the tapered portions 65b and 66b are provided at the downstream
side in the fuel gas flowing direction of the rectification member
55. Accordingly, since the front end portion of the flame
stabilizer 54 is equipped with the widened portions 61b and 62b,
the flame may be reliably stabilized. Then, since the front end
portion of the rectification member 55 is equipped with the tapered
portions 65b and 66b, the distance between the flame stabilizer 54
and the rectification member 55 in the fuel gas flowing direction
may become substantially uniform.
[0198] Further, in the combustion burner of the first embodiment,
the flame stabilizer 54 is formed in a structure in which two first
flame stabilizing members 61 and 62 provided in the horizontal
direction while being parallel to each other in the vertical
direction with a predetermined gap therebetween and two second
flame stabilizing members 63 and 64 provided in the vertical
direction while being parallel to each other in the horizontal
direction with a predetermined gap therebetween are disposed so as
to intersect one another. Accordingly, since the flame stabilizer
54 is formed in a double cross structure, a sufficient flame
stabilizing function may be ensured.
[0199] Further, in the combustion burner of the first embodiment,
the widened portions 61b and 62b are provided at the downstream
side in the fuel gas flowing direction of the flame stabilizer 54,
and the rectification member 75 is provided at a position where the
rectification member does not face the widened portions 61b and
62b. Accordingly, since the rectification member 75 is provided at
a position where the rectification member does not face the widened
portions 61b and 62b of the flame stabilizer 54, the flow velocity
of the fuel gas becomes substantially uniform without narrowing the
fuel gas passages between the fuel nozzle 51 and the widened
portions 61b and 62b of the flame stabilizer 54, and hence the
deposit of the pulverized coal fuel of the fuel nozzle 51 or the
attachment of the pulverized coal fuel to the flame stabilizer 54
may be suppressed.
Second Embodiment
[0200] FIG. 11 is a cross-sectional view illustrating a combustion
burner according to a second embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0201] In the combustion burner of the second embodiment, as
illustrated in FIG. 11, the combustion burner 21 is equipped with
the fuel nozzle 51, the secondary air nozzle 52, and the tertiary
air nozzle 53 which are provided from the center side of the
combustion burner, and is equipped with a flame stabilizer 121.
Then, a rectification member 122 is provided between the inner wall
surface of the fuel nozzle 51 and the flame stabilizer 121.
[0202] The flame stabilizer 121 is disposed at the axis center of
the fuel nozzle 51 so as to follow the horizontal direction, and
the configuration is substantially the same as those of the first
flame stabilizing members 61 and 62 described in the first
embodiment. That is, the flame stabilizer 121 includes a widened
portion of which the width is widened toward the downstream side in
the fuel gas flowing direction, and the front end thereof becomes a
plane perpendicular to the fuel gas flowing direction.
[0203] Since the rectification member 122 is fixed along the inner
wall surface of the fuel nozzle 51, the rectification member has a
predetermined gap with respect to the flame stabilizer 121. That
is, the rectification member 122 includes first rectification
members 123 and 124 following the horizontal direction, and the
downstream end portion in the fuel gas flowing direction is
equipped with inclined portions 123a and 124a which face the upper
and lower sides of the widened portion of the flame stabilizer 121.
In this case, the first rectification members 123 and 124 are
directly fixed to the inner wall surface of the fuel nozzle 51, but
a support member may extend from the upstream portion of the fuel
nozzle 51 so as to support the first rectification members 123 and
124.
[0204] For this reason, the flame stabilizer 121 and the
rectification member 122 are formed in a shape in which the widened
portion faces the inclined portions 123a and 124a, and the distance
between the flame stabilizer 121 and the rectification member 122
in a direction perpendicular to the fuel gas flowing direction is
substantially equal in the fuel gas flowing direction.
[0205] Accordingly, since the fuel gas is divided by the flame
stabilizer 121 at the opening portion 51a of the fuel nozzle 51,
the inner flame stabilization of the combustion flame may be
performed by the fuel gas going round to the front end surface side
of the flame stabilizer, the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air, and the NOx production amount in
the outer peripheral portion of the combustion flame is reduced.
Further, at this time, since the flow of the fuel gas flowing
between the rectification member 122 and flame stabilizer 121 is
rectified by the rectification member, the separation of the fuel
gas disappears. Further, the flow velocity of the fuel gas flowing
therethrough becomes uniform, and the flow velocity thereof is
reduced. Thus, the flame stabilizer 121 may ensure a sufficient
flame stabilization ability at the front end portion thereof.
[0206] In this way, in the combustion burner of the second
embodiment, the rectification member 122 is provided in the inner
wall surface of the fuel nozzle 51. Accordingly, since the
rectification member 122 is provided in the inner wall surface of
the fuel nozzle 51, a separate attachment member or the like is not
needed. Accordingly, the rectification member 122 may be simply
supported. Thus, the assembling workability of the rectification
member 122 may be improved, and the manufacturing cost may be
reduced. Further, the mixing of the secondary air may be delayed,
and hence the outer peripheral zone with a high temperature and a
high oxygen concentration may be reduced.
Third Embodiment
[0207] FIG. 12 is a cross-sectional view illustrating a combustion
burner according to a third embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0208] In the combustion burner of the third embodiment, as
illustrated in FIG. 12, the combustion burner 21 is equipped with
the fuel nozzle 51, the secondary air nozzle 52, and the tertiary
air nozzle 53 which are provided from the center side of the
combustion burner, and is equipped with a flame stabilizer 131.
Then, a rectification member 135 is provided inside the flame
stabilizer 131.
[0209] The flame stabilizer 131 is disposed at the axis center of
the fuel nozzle 51 so as to follow the horizontal direction, and
two flame stabilizing members following the horizontal direction
and two flame stabilizing members following the vertical direction
are disposed so as to intersect one another. Further, the
rectification member 135 includes a first rectification member 136
which is positioned between the respective flame stabilizing
members of the flame stabilizer 131 so as to be formed in a cross
shape by the intersection in the horizontal direction and the
vertical direction and second rectification members 137 and 138
which are positioned at the upstream side in relation to the flame
stabilizer 131 and the rectification member 136 and are fixed to
the inner wall surface of the fuel nozzle 51.
[0210] Since the first rectification member 136 is fixed to the
inner wall surface of the fuel nozzle 51, the first rectification
member has a predetermined gap with respect to the flame stabilizer
131. Further, the second rectification members 137 and 138 are
fixed to the inner wall surface of the fuel nozzle 51 at the
upstream side of the fuel gas in relation to the flame stabilizer
131, and hence the fuel gas flowing through the fuel nozzle 51 may
be guided to the center side thereof.
[0211] Accordingly, since the fuel gas is divided by flame
stabilizers 132 and 133 at the fuel nozzle 51, the inner flame
stabilization of the combustion flame may be performed by the fuel
gas going round to the front end surface side of the flame
stabilizer, the temperature of the outer peripheral portion of the
combustion flame under a high oxygen atmosphere becomes low by the
secondary air, and the NOx production amount in the outer
peripheral portion of the combustion flame is reduced. Further, at
this time, since the fuel gas is guided toward the center side of
the fuel nozzle 51 by the second rectification members 137 and 138
and the fuel gas flowing between the first rectification member 136
and the flame stabilizer 132 is rectified by the first
rectification member, the separation of the fuel gas disappears,
and in addition, the flow velocity of the fuel gas flowing
therethrough becomes uniform and is reduced. Thus, the flame
stabilizer 132 may ensure a sufficient flame stabilization ability
at the front end portion thereof.
[0212] In this way, in the combustion burner of the third
embodiment, as the rectification member 135, there are provided the
first rectification member 136 which is positioned inside the flame
stabilizer 131 so as to form a cross shape and the second
rectification members 137 and 138 which are positioned at the
upstream side in relation to the flame stabilizer 131. Accordingly,
the fuel gas flowing through the fuel nozzle 51 is guided to the
center side of the fuel nozzle 51 by the second rectification
members 137 and 138, and the flow thereof is rectified by the first
rectification member 136, so that the appropriate flow of the fuel
gas may be realized.
Fourth Embodiment
[0213] FIG. 13 is a cross-sectional view illustrating a combustion
burner according to a fourth embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0214] In the combustion burner of the fourth embodiment, as
illustrated in FIG. 13, the combustion burner 21 is equipped with
the fuel nozzle 51, the secondary air nozzle 52, and the tertiary
air nozzle 53 which are provided from the center side of the
combustion burner, and is equipped with the flame stabilizer 54.
Then, a rectification member 141 is provided inside the flame
stabilizer 54. The flame stabilizer 131 is disposed at the axis
center of the fuel nozzle 51 so as to follow the horizontal
direction. The rectification member 141 forms a cross shape by the
intersection of the horizontal direction and the vertical direction
inside the flame stabilizer 54. In this case, the front end portion
of the rectification member 141 is positioned at the upstream side
in relation to the flame stabilizer 54.
[0215] Accordingly, since the fuel gas is divided by the flame
stabilizer 54 at the fuel nozzle 51, the inner flame stabilization
of the combustion flame may be performed by the fuel gas going
round to the front end surface side of the flame stabilizer, the
temperature of the outer peripheral portion of the combustion flame
under a high oxygen atmosphere becomes low by the secondary air,
and the NOx production amount in the outer peripheral portion of
the combustion flame is reduced. Further, at this time, since the
fuel gas flowing between the rectification member 141 and the flame
stabilizer 54 is rectified by the rectification member, the
separation of the fuel gas disappears. Further, the flow velocity
of the fuel gas flowing therethrough becomes uniform, and the flow
velocity thereof is reduced. Thus, the flame stabilizer 54 may
ensure a sufficient flame stabilization ability at the front end
portion thereof.
[0216] In this way, in the combustion burner of the fourth
embodiment, the rectification member 141 is provided inside the
flame stabilizer 54 so as to be fixed to the inner wall surface of
the fuel nozzle 51. Accordingly, the flow of the fuel gas flowing
through the fuel nozzle 51 is rectified by the rectification member
141, so that the appropriate flow of the fuel gas may be
realized.
Fifth Embodiment
[0217] FIG. 14 is a cross-sectional view illustrating a combustion
burner according to a fifth embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0218] In the combustion burner of the fifth embodiment, as
illustrated in FIG. 14, the combustion burner 21 is equipped with
the fuel nozzle 51, the secondary air nozzle 52, and the tertiary
air nozzle 53 which are provided from the center side of the
combustion burner, and is equipped with the flame stabilizer 121.
Then, a rectification member 151 is provided between the inner wall
surface of the fuel nozzle 51 and the flame stabilizer 121.
[0219] The flame stabilizer 121 is disposed at the axis center of
the fuel nozzle 51 so as to follow the horizontal direction, and
the configuration is substantially the same as those of the first
flame stabilizing members 61 and 62 described in the first
embodiment. The rectification member 151 is disposed so as to have
a predetermined gap with respect to the inner wall surface of the
fuel nozzle 51 and have a predetermined gap with respect to the
flame stabilizer 121. That is, the rectification member 151 is
formed in a structure in which first rectification members 152 and
153 following the horizontal direction and second rectification
members (not illustrated) following the vertical direction (the up
and down direction) are disposed so as to form a frame shape. Then,
the respective first rectification members 152 and 153 are disposed
so that the front end portions thereof approach the flame
stabilizer 121 and the rear end portions thereof are separated from
the flame stabilizer 121. Furthermore, the respective second
rectification members also have the same structure.
[0220] In this case, since the front end portions of the respective
rectification members 152 and 153 approach the flame stabilizer
121, the gap between the rectification members 152 and 153 and the
flame stabilizer 121 is narrowed as it goes toward the downstream
side.
[0221] Accordingly, since the fuel gas is divided by the flame
stabilizer 121 at the opening portion of the fuel nozzle 51, the
inner flame stabilization of the combustion flame may be performed
by the fuel gas going round to the front end surface side of the
flame stabilizer, the temperature of the outer peripheral portion
of the combustion flame under a high oxygen atmosphere becomes low
by the secondary air, and the NOx production amount in the outer
peripheral portion of the combustion flame is reduced. Further, at
this time, since the fuel gas flowing between the rectification
member 151 and the flame stabilizer 121 is rectified by the
rectification member, the separation of the fuel gas disappears.
Further, the flow velocity of the fuel gas flowing therethrough
becomes uniform, and the flow velocity thereof is reduced. Thus,
the flame stabilizer 121 may ensure a sufficient flame
stabilization ability at the front end portion thereof.
[0222] In this way, in the combustion burner of the fifth
embodiment, the rectification member 151 is provided outside the
flame stabilizer 121 so as to be fixed to the inner wall surface of
the fuel nozzle 51, and the front end portion thereof is inclined
so as to approach the flame stabilizer 121. Accordingly, the flow
of the fuel gas flowing through the fuel nozzle 51 is rectified by
the rectification member 151, so that the appropriate flow of the
fuel gas may be realized.
Sixth Embodiment
[0223] FIG. 15 is a cross-sectional view illustrating a combustion
burner according to a sixth embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0224] In the combustion burner of the sixth embodiment, as
illustrated in FIG. 15, the combustion burner 21 is equipped with
the fuel nozzle 51, the secondary air nozzle 52, and the tertiary
air nozzle 53 which are provided from the center side of the
combustion burner, and is equipped with a flame stabilizer 161. The
flame stabilizer 161 is formed in a so-called double cross split
structure in which first flame stabilizing members 162 and 163
following the horizontal direction and second flame stabilizing
members (not illustrated) following the vertical direction are
disposed in a cross shape. Then, the first flame stabilizing
members 162 and 163 are formed in a plate shape with a
predetermined thickness. Furthermore, the respective second flame
stabilizing members also have the same structure.
[0225] In the embodiment, the outer surfaces of the respective
flame stabilizing members 162 and 163 in the flame stabilizer 161
serve as the rectification members.
[0226] Accordingly, since the fuel gas is divided by the flame
stabilizer 161 at the opening portion 51a of the fuel nozzle 51,
the inner flame stabilization of the combustion flame may be
performed by the fuel gas going round to the front end surface side
of the flame stabilizer, the temperature of the outer peripheral
portion of the combustion flame under a high oxygen atmosphere
becomes low by the secondary air, and the NOx production amount in
the outer peripheral portion of the combustion flame is reduced.
Further, at this time, since the fuel gas flowing between the fuel
nozzle 51 and the flame stabilizer 161 is rectified by the outer
surface of the flame stabilizer 161, the separation of the fuel gas
disappears. Further, the flow velocity of the fuel gas flowing
therethrough becomes uniform, and the flow velocity thereof is
reduced. Thus, the flame stabilizer 161 may ensure a sufficient
flame stabilization ability at the front end portion thereof.
[0227] Furthermore, in the above-described respective embodiments,
the configurations of the respective flame stabilizers have been
described by various examples, but the configuration is not limited
to the above-described configuration. That is, the burner of the
invention is used to realize the inner flame stabilization. Then,
the flame stabilizer may be provided near the axis of the fuel
nozzle instead of the inner wall surface of the fuel nozzle, the
number or the position of the flame stabilizing members may be
appropriately set, and the flame stabilizing member may be
separated from the inner wall surface of the fuel nozzle. Further,
the configuration of the rectification member has been described by
various examples, but the configuration is not limited to the
above-described configuration. That is, the rectification member
may be provided between the inner wall surface of the fuel nozzle
and the flame stabilizer. In a case where plural flame stabilizers
are provided, the rectification member may be provided between the
flame stabilizers.
[0228] Further, in the above-described respective embodiments, as
the combustion device 12, four combustion burners 21, 22, 23, 24,
and 25 respectively provided in the wall surface of the furnace 11
are disposed as a five stages in the vertical direction, but the
configuration is not limited thereto. That is, the combustion
burner may be disposed at the corner instead of the wall surface.
Further, the combustion device is not limited to the turning
combustion type, and may be a front combustion type in which the
combustion burner is disposed in one wall surface or an opposed
combustion type in which the combustion burners are disposed in two
wall surfaces so as to be opposed to each other.
[0229] Further, the flame stabilizer of the invention is equipped
with the widened portion having a triangular cross-sectional shape,
but the shape is not limited thereto. That is, the shape may be a
square shape or the widened portion may not be provided.
Seventh Embodiment
[0230] As the combustion burner of the conventional
pulverized-coal-combustion boiler, for example, the combustion
burner disclosed in Patent Literature 1 is known. In the combustion
device disclosed in Patent Literature 1, the flame stabilizer is
provided between the center inside the pulverized coal ejecting
hole (the primary passage) and the outer peripheral portion, and
thus the pulverized coal condensed flow is made to collide with the
flame stabilizer. Thus, the low NOx combustion may be stably
performed in a wide load range.
[0231] However, in the conventional combustion device, when the
combustion gas obtained by mixing the pulverized coal and the air
collides with the flame stabilizer, the separation of the flow
occurs at the rear end portion of the flame stabilizer, and hence
it is difficult to sufficiently exhibit the flame stabilization
ability at the front end portion of the flame stabilizer. Thus,
there is a problem in which NOx is produced by the ignition
occurring at the outside of the flame stabilizer.
[0232] The invention is made to solve the above-described problems,
and it is an object of the invention to provide a combustion burner
capable of reducing a NOx production amount by realizing an
appropriate flow of a fuel gas obtained by mixing solid fuel and
air.
[0233] FIG. 16 is a front view illustrating a combustion burner
according to a seventh embodiment of the invention, FIG. 17 is a
cross-sectional view illustrating the combustion burner of the
seventh embodiment, FIG. 18 is a schematic configuration diagram
illustrating a pulverized-coal-combustion boiler that employs the
combustion burner of the seventh embodiment, and FIG. 19 is a plan
view illustrating the combustion burner of the
pulverized-coal-combustion boiler of the seventh embodiment.
[0234] The pulverized-coal-combustion boiler that employs the
combustion burner of the seventh embodiment is a boiler which burns
pulverized coal by the combustion burner using pulverized coal
obtained by milling coal as the solid fuel and collects heat
generated by the combustion.
[0235] In the seventh embodiment, as illustrated in FIG. 18, a
pulverized-coal-combustion boiler 210 is the conventional boiler,
and includes a furnace 211 and a combustion device 212. The furnace
211 is formed in a hollow square cylindrical shape and is provided
in the vertical direction, and the combustion device 212 is
provided in the lower portion of the furnace wall forming the
furnace 211.
[0236] The combustion device 212 includes plural combustion burners
221, 222, 223, 224, and 225 which are attached to the furnace wall.
In the embodiment, the combustion burners 221, 222, 223, 224, and
225 are disposed as one set in the circumferential direction at
four equal intervals therebetween, and five sets, that is, five
stages are disposed in the vertical direction.
[0237] Then, the respective combustion burners 221, 222, 223, 224,
and 225 are connected to coal pulverizers (mills) 231, 232, 233,
234, and 235 through pulverized coal supply pipes 226, 227, 228,
229, and 230. Although not illustrated in the drawings, the coal
pulverizers 231, 232, 233, 234, and 235 have a configuration in
which milling tables are supported in a rotational driving state
with rotation axes along the vertical direction inside a housing
and plural milling rollers are provided while facing the upper
sides of the milling tables and are supported so as to be rotatable
along with the rotation of the milling tables. Accordingly, when
coal is input between plural milling rollers and plural milling
tables, the coal is milled into a predetermined size therein. Thus,
pulverized coal which is classified by transportation air (primary
air) may be supplied from pulverized coal supply pipes 226, 227,
228, 229, and 230 to the combustion burners 221, 222, 223, 224, and
225.
[0238] Further, in the furnace 211, wind boxes 236 are provided at
the attachment positions of the respective combustion burners 221,
222, 223, 224, and 225, where one end portion of an air duct 237 is
connected to the wind box 236 and an air blower 238 is attached to
the other end portion of the air duct 237. Accordingly, combustion
air (secondary air and tertiary air) sent by the air blower 238 may
be supplied from the air duct 237 to the wind box 236, and may be
supplied from the wind box 236 to each of the respective combustion
burners 221, 222, 223, 224, and 225.
[0239] For this reason, in the combustion device 212, the
respective combustion burners 221, 222, 223, 224, and 225 may blow
the pulverized fuel-air mixture (fuel gas) obtained by mixing the
pulverized coal and the primary air into the furnace 211 and may
blow the secondary air into the furnace 211. Then, a flame may be
formed by igniting the pulverized fuel-air mixture through an
ignition torch (not illustrated).
[0240] Furthermore, when generally activating the boiler, the
respective combustion burners 221, 222, 223, 224, and 225 form a
flame by ejecting oil fuel into the furnace 211.
[0241] A flue gas duct 240 is connected to the upper portion of the
furnace 211, and the flue gas duct 240 is equipped with
superheaters 241 and 242, reheaters 243 and 244, and economizers
245, 246, and 247 as convection heat transfer portions for
collecting the heat of the flue gas. Accordingly, a heat exchange
is performed between water and a flue gas that is produced by the
combustion in the furnace 211.
[0242] The downstream side of the flue gas duct 240 is connected
with a flue gas pipe 248 into which the flue gas subjected to heat
exchange is discharged. An air heater 249 is provided between the
flue gas pipe 248 and the air duct 237, and a heat exchange is
performed between the air flowing through the air duct 237 and the
flue gas flowing through the flue gas pipe 248, so that the
combustion air flowing through the combustion burners 221, 222,
223, 224, and 225 may increase in temperature.
[0243] Furthermore, although not illustrated in the drawings, the
flue gas pipe 248 is equipped with a denitration device, an
electronic precipitator, an inducing air blower, and a
desulfurization device, and the downstream end portion thereof is
equipped with a stack.
[0244] Accordingly, when the coal pulverizers 231, 232, 233, 234,
and 235 are driven, pulverized coal produced therein is supplied
along with the transportation air to the combustion burners 221,
222, 223, 224, and 225 through pulverized coal supply pipes 226,
227, 228, 229, and 230. Further, the heated combustion air is
supplied from the air duct 237 to the respective combustion burners
221, 222, 223, 224, and 225 through the wind boxes 236. Then, the
combustion burners 221, 222, 223, 224, and 225 blow the pulverized
fuel-air mixture obtained by mixing the pulverized coal and the
transportation air to the furnace 211, blow the combustion air to
the furnace 211, and ignite the pulverized fuel-air mixture and the
air at this time so as to form a flame. In the furnace 211, when
the flame is generated by the combustion of the pulverized fuel-air
mixture and the combustion air and the flame is generated at the
lower portion inside the furnace 211, the combustion gas (the flue
gas) rises inside the furnace 211 so as to be discharged to the
flue gas duct 240.
[0245] Furthermore, the inside of the furnace 211 is maintained at
the reduction atmosphere in a manner such that the air supply
amount with respect to the pulverized coal supply amount becomes
smaller than the theoretical air amount. Then, when NOx produced by
the combustion of the pulverized coal is reduced in the furnace 211
and additional air is additionally supplied thereto, the
oxidization combustion of the pulverized coal is completed and
hence the production amount of NOx caused by the combustion of the
pulverized coal is reduced.
[0246] At this time, water supplied from a water feeding pump (not
illustrated) is preheated by the economizers 245, 246, and 247, is
supplied to a steam drum (not illustrated), and is heated while
being supplied to respective water pipes (not illustrated) of the
furnace wall so as to become saturated steam. Then, the saturated
steam is transported to a steam drum (not illustrated). Further,
the saturated steam of a steam drum (not illustrated) is introduced
into the superheaters 241 and 242 and is superheated by the
combustion gas. The superheated steam produced by the superheaters
241 and 242 is supplied to a power generation plant (not
illustrated) (for example, a turbine or the like). Further, the
steam which is extracted during the expanding process in the
turbine is introduced into the reheaters 243 and 244, is
superheated again, and is returned to the turbine. Furthermore, the
furnace 211 of a drum type (steam drum) has been described, but the
invention is not limited to the structure.
[0247] Subsequently, a harmful substance such as NOx is removed
from the flue gas which passes through the economizers 245, 246,
and 247 of the flue gas duct 240 by a catalyst in the flue gas pipe
248, a particulate substance is removed therefrom by the electronic
precipitator, and a sulfur content is removed therefrom by the
desulfurization device. Then, the flue gas is discharged to the
atmosphere through the stack.
[0248] Here, the combustion device 212 will be described in detail,
but since the respective combustion burners 221, 222, 223, 224, and
225 constituting the combustion device 212 have substantially the
same configuration, only the combustion burner 221 that is
positioned at the uppermost stage will be described.
[0249] As illustrated in FIG. 19, the combustion burner 221
includes the combustion burners 221a, 221b, 221c, and 221d which
are provided at four wall surfaces of the furnace 211. The
respective combustion burners 221a, 221b, 221c, and 221d are
connected with respective branch pipes 226a, 226b, 226c, and 226d
which are branched from a pulverized coal supply pipe 226, and are
connected with respective branch pipes 237a, 237b, 237c, and 237d
branched from the air duct 237.
[0250] Accordingly, the respective combustion burners 221a, 221b,
221c, and 221d which are positioned at the respective wall surfaces
of the furnace 211 blow the pulverized fuel-air mixture obtained by
mixing the pulverized coal and the transportation air to the
furnace 211 and blow the combustion air to the outside of the
pulverized fuel-air mixture. Then, the pulverized fuel-air mixture
is ignited from the respective combustion burners 221a, 221b, 221c,
and 221d, so that four flames F1, F2, F3, and F4 may be formed. The
flames F1, F2, F3, and F4 become a flame swirl flow that turns in
the counter-clockwise direction when viewed from the upside of the
furnace 211 (in FIG. 19).
[0251] As illustrated in FIGS. 16 and 17, in the combustion burner
221 (221a, 221b, 221c, and 221d) with such a configuration, the
combustion burner is equipped with a fuel nozzle 251, a secondary
air nozzle 252, and a tertiary air nozzle 253 which are provided
from the center side thereof and is equipped with a flame
stabilizer 254. The fuel nozzle 251 may blow the fuel gas (the
pulverized fuel-air mixture) obtained by mixing the pulverized coal
(the solid fuel) with the transportation air (the primary air). The
secondary air nozzle 252 is disposed at the outside of the first
nozzle 251 and may blow the combustion air (the secondary air) to
the outer peripheral side of the fuel gas ejected from the fuel
nozzle 251. The tertiary air nozzle 253 is disposed at the outside
of the secondary air nozzle 252 and may blow the tertiary air to
the outer peripheral side of the secondary air ejected from the
secondary air nozzle 252.
[0252] Further, the flame stabilizer 254 is disposed inside the
fuel nozzle 51 so as to be positioned at the downstream side of the
fuel gas blowing direction and near the axis center, and serves to
ignite and stabilize the fuel gas. The flame stabilizer 254 is
formed in a so-called double cross split structure in which first
flame stabilizing members 261 and 262 following the horizontal
direction and second flame stabilizing members 263 and 264
following the vertical direction (the up and down direction) are
disposed in a cross shape. Then, the respective first flame
stabilizing members 261 and 262 include flat portions 261a and 262a
each formed in a flat plate shape having a uniform thickness and
widened portions 61b and 262b integrally formed with the front end
portions of the flat portions 261a and 262a (the downstream end
portions in the fuel gas flowing direction). Each cross-section of
the widened portions 261b and 262b is formed in an isosceles
triangular shape, each width of the widened portions is widened
toward the downstream side in the fuel gas flowing direction, and
each front end thereof is formed as a plane perpendicular to the
fuel gas flowing direction. Furthermore, although not illustrated
in the drawings, the respective second flame stabilizing members
263 and 264 also have the same structure.
[0253] For this reason, each of the fuel nozzle 251 and the
secondary air nozzle 252 has an elongated tubular shape, the fuel
nozzle 251 includes a rectangular opening portion 251a, and the
secondary air nozzle 252 includes a rectangular annular opening
portion 252a. Thus, the fuel nozzle 251 and the secondary air
nozzle 252 are formed as a double tube structure. The tertiary air
nozzle 253 is disposed as a double tube structure at the outside of
the fuel nozzle 251 and the secondary air nozzle 252, and includes
a rectangular annular opening portion 253a. As a result, the
opening portion 252a of the secondary air nozzle 252 is disposed at
the outside of the opening portion 251a of the fuel nozzle 251, and
the opening portion 253a of the tertiary air nozzle 253 is disposed
at the outside of the opening portion 252a of the secondary air
nozzle 252. Furthermore, the tertiary air nozzle 253 may not be
disposed as a double tube structure, and the tertiary air nozzle
may be obtained by separately disposing plural nozzles at the outer
peripheral side of the secondary air nozzle 252.
[0254] In the nozzles 251, 252, and 253, the opening portions 251a,
252a, and 253a are disposed so as to be flush with one another.
Further, the flame stabilizer 254 is supported by the inner wall
surface of the fuel nozzle 251 or a plate member (not illustrated)
from the upstream side of the passage through which the fuel gas
flows. Further, since plural flame stabilizing members 261, 262,
263, and 264 are disposed as the flame stabilizer 254 inside the
fuel nozzle 251, the fuel gas passage is divided into nine
segments. Then, in the flame stabilizer 254, the widened portions
261b and 262b of which the widths are wide are positioned at the
front end portions thereof, and the front end surfaces of the
widened portions 261b and 262b are evenly disposed so as to be
flush with the opening portion 251a.
[0255] Further, in the combustion burner 221 of the seventh
embodiment, a guide member 255 is provided so as to guide the fuel
gas flowing through the fuel nozzle 251 toward the axis center
side. The guide member 255 guides the fuel gas in a direction in
which the fuel gas is separated from the secondary air blowing from
the secondary air nozzle 252.
[0256] The guide member 255 is disposed in the inner wall surface
of the front end portion of the fuel nozzle 251 in the
circumferential direction. That is, the guide member 255 includes
an upper guide member 265 that is disposed along the upper wall
surface of the fuel nozzle 251, a lower guide member 266 that is
disposed along the lower wall surface of the fuel nozzle 251, and
left and right guide members 267 and 268 that are disposed along
the left and right wall surfaces of the fuel nozzle 251. Then, the
guide member 255 is disposed at the front end portion of the fuel
nozzle 251 so as to face the widened portions 261b and 262b of the
flame stabilizer 254. Then, the guide member 255 is provided with
an inclined surface 269 of which the cross-section is formed in a
triangular shape and the width is widened toward the downstream
side in the fuel gas flowing direction, the front end thereof is
formed as a plane perpendicular to the fuel gas flowing direction.
Then, the inclined surface is flush with the opening portions 251a
and 252a. Furthermore, the guide member 55 is formed by notching a
position intersecting the respective flame stabilizing members 261,
262, 263, and 264.
[0257] Accordingly, in the combustion burner 221, the fuel gas
obtained by mixing the pulverized coal with the primary air blows
from the opening portion 251a of the fuel nozzle 251 into the
furnace, the secondary air at the outside thereof blows from the
opening portion 252a of the secondary air nozzle 252 into the
furnace, and the tertiary air at the outside thereof blows from the
opening portion 253a of the tertiary air nozzle 253 into the
furnace. At this time, the fuel gas is divided by the flame
stabilizer 254 at the opening portion 251a of the fuel nozzle 251,
and is ignited so as to become the combustion gas. Further, since
the secondary air blows to the outer periphery of the fuel gas, the
combustion of the fuel gas is promoted. Further, since the tertiary
air blows to the outer periphery of the combustion flame, the
combustion may be optimally performed by adjusting the ratio
between the secondary air and the tertiary air.
[0258] Then, since the flame stabilizer 254 is formed in a split
shape in the combustion burner 221, the fuel gas is divided by the
flame stabilizer 254 at the opening portion 251a of the fuel nozzle
251. At this time, the flame stabilizer 254 is disposed at the
center zone of the opening portion 251a of the fuel nozzle 251, and
the fuel gas is ignited and stabilized at the center zone. Thus,
the inner flame stabilization (the flame stabilization at the
center zone of the opening portion 251a of the fuel nozzle 251) of
the combustion flame is realized.
[0259] For this reason, compared to the configuration in which the
outer flame stabilization of the combustion flame is performed, the
temperature of the outer peripheral portion of the combustion flame
becomes low, and hence the temperature of the outer peripheral
portion of the combustion flame under the high oxygen atmosphere by
the secondary air may become low. Thus, the NOx production amount
at the outer peripheral portion of the combustion flame is
reduced.
[0260] Further, since the combustion burner 221 employs a
configuration in which the inner flame stabilization is performed,
it is desirable to supply the fuel gas and the combustion air (the
secondary air and the tertiary air) as a straight flow. That is, it
is desirable that the fuel nozzle 251 have a structure in which the
secondary air nozzle 252 and the tertiary air nozzle 253 supply the
fuel gas, the secondary air, and the tertiary air as a straight
flow instead of a swirl flow. Since the fuel gas, the secondary
air, and the tertiary air are ejected as the straight flow so as to
form the combustion flame, the circulation of the gas inside the
combustion flame is suppressed in the configuration in which the
inner flame stabilization of the combustion flame is performed.
Accordingly, the outer peripheral portion of the combustion flame
is maintained in a low temperature, and the NOx production amount
caused by the mixture with the secondary air is reduced.
[0261] Further, in the combustion burner 221, since the guide
member 255 is disposed so as to be positioned in the entire
circumference of the front end portion of the fuel nozzle 251, the
fuel gas flowing through the fuel nozzle 251 is guided toward the
center side thereof, that is, the flame stabilizer 254 by the
inclined surface 269 of the guide member 255. Then, the fuel gas
blowing into the furnace by the fuel nozzle 251 is guided in a
direction in which the fuel gas is separated from the secondary air
blowing from the secondary air nozzle 252. For this reason, since
the fuel gas is separated from the secondary air of which the speed
is faster than that of the fuel gas, the inner flame stabilization
is appropriately performed by the flame stabilizer 254. Further,
since the fuel gas is separated from the secondary air and the NOx
production amount caused by the mixture with the secondary air is
reduced in the fuel gas. Furthermore, the pulverized coal may be
appropriately supplied toward the flame stabilizer 254.
[0262] In this way, in the combustion burner of the seventh
embodiment, there are provided the fuel nozzle 251 which may blow
the fuel gas obtained by mixing the pulverized coal with the
primary air and the secondary air nozzle 252 which may blow the
secondary air from the outside of the fuel nozzle 251. Also, the
flame stabilizer 254 is provided at the front end portion of the
fuel nozzle 251 so as to be near the axis center, and the guide
member 255 is provided so as to guide the fuel gas flowing through
the fuel nozzle 251 toward the axis center side.
[0263] Accordingly, the fuel gas flowing through the fuel nozzle
251 is guided toward the axis center side of the fuel nozzle 251,
that is, the flame stabilizer 254 by the guide member 255, and the
appropriate flow of the fuel gas inside the fuel nozzle 251 may be
realized. As a result, the inner flame stabilization performance
using the flame stabilizer 254 may be improved.
[0264] Further, in the combustion burner of the seventh embodiment,
the guide member 255 guides the fuel gas in a direction in which
the fuel gas is separated from the secondary air blowing from the
secondary air nozzle 252. Accordingly, the fuel gas is guided by
the guide member 255 in a direction in which the fuel gas is
separated from the secondary air and the mixing of the fuel gas and
the secondary air is suppressed, the inner flame stabilization
performance using the flame stabilizer 254 may be improved, and the
outer peripheral portion of the combustion flame is maintained at
the low temperature. Thus, the NOx production amount caused by the
mixing of the combustion gas and the secondary air may be
reduced.
[0265] Further, in the combustion burner of the seventh embodiment,
the guide member 255 is disposed along the inner wall surface of
the fuel nozzle 251. Accordingly, the fuel gas flowing through the
fuel nozzle 251 may be effectively guided to the flame stabilizer
254 throughout the entire area of the fuel nozzle 251, and the fuel
gas may be guided in a direction in which the fuel gas is separated
from the secondary air. The inner flame stabilization performance
using the flame stabilizer 254 may be improved.
[0266] Further, in the combustion burner of the seventh embodiment,
the guide member 255 is disposed at the front end portion of the
fuel nozzle 251 so as to face the flame stabilizer 254. In this
case, the guide member 255 is disposed in the flame stabilizer 254
so as to face the widened portions 261b and 262b. Accordingly,
since the fuel gas is guided toward the widened portions 261b and
262b of the flame stabilizer 254 by the guide member 255, the
sufficient flame stabilizing function may be ensured, and the inner
flame stabilization performance may be improved.
Eighth Embodiment
[0267] FIG. 20 is a cross-sectional view illustrating a combustion
burner according to an eighth embodiment of the invention.
Furthermore, the same reference sign will be given to the component
having the same function as that of the above-described embodiment,
and the detailed description thereof will not be repeated.
[0268] In the combustion burner of the eighth embodiment, as
illustrated in FIG. 20, the combustion burner 221 is equipped with
the fuel nozzle 251, the secondary air nozzle 252, and the tertiary
air nozzle 253 which are provided from the center side of the
combustion burner, and is equipped with the flame stabilizer 254.
Then, since the fuel gas flowing through the fuel nozzle 251 is
guided to the axis center side, a guide member 271 is provided so
as to guide the fuel gas in a direction in which the fuel gas is
separated from the secondary air blowing from the secondary air
nozzle 252.
[0269] The guide member 271 is disposed in the inner wall surface
of the fuel nozzle 251 along the circumferential direction so as to
be positioned at a position where the guide member does not face
the flame stabilizer 254 disposed inside the fuel nozzle 251, that
is, the upstream side of the flame stabilizer 254 in the fuel gas
flowing direction. The guide member 271 is formed in the inner wall
surface of the fuel nozzle 251 in an annular shape which protrudes
toward the flame stabilizer 254, and is equipped with a guide
surface (an inclined surface or a curved surface) 272 which guides
the fuel gas inside the fuel nozzle 251 toward the axis center
side.
[0270] Accordingly, since the guide member 271 is disposed so as to
be positioned at the entire circumference of the front end portion
of the fuel nozzle 251 in the combustion burner 221, the fuel gas
flowing through the fuel nozzle 251 is guided toward the axis
center side of the fuel nozzle, that is, the flame stabilizer 254
by the guide surface 272 of the guide member 271. Then, the fuel
gas flowing from the fuel nozzle 251 into the furnace is guided in
a direction in which the fuel gas is separated from the secondary
air blowing from the secondary air nozzle 252. For this reason,
since the fuel gas is separated from the secondary air of which the
speed is faster than that of the fuel gas, the inner flame
stabilization using the flame stabilizer 254 may be performed.
Further, since the fuel gas is separated from the secondary air and
the NOx production amount caused by the mixture with the secondary
air is reduced in the fuel gas.
[0271] In this way, in the combustion burner of the eighth
embodiment, there are provided the fuel nozzle 251 which may blow
the fuel gas obtained by mixing the pulverized coal with the
primary air and the secondary air nozzle 252 which may blow the
secondary air from the outside of the fuel nozzle 251. Also, the
flame stabilizer 254 is provided at the front end portion of the
fuel nozzle 251 so as to be near the axis center, and the guide
member 271 which guides the fuel gas flowing through the fuel
nozzle 251 toward the axis center side is provided at the upstream
side of the flame stabilizer 254 in the fuel gas flowing
direction.
[0272] Accordingly, the fuel gas flowing through the fuel nozzle
251 is guided toward the axis center side of the fuel nozzle 251,
that is, the flame stabilizer 254 by the guide member 271, and the
appropriate flow of the fuel gas inside the fuel nozzle 251 may be
realized. As a result, the inner flame stabilization performance
using the flame stabilizer 254 may be improved. Further, since the
guide member 271 is provided at the upstream side in relation to
the flame stabilizer 254, the fuel gas may be effectively guide to
the flame stabilizer 254, and the inner flame stabilization
performance using the flame stabilizer 254 may be improved.
Further, since the guide member 271 is not provided at the front
end side inside the fuel nozzle 251, the guide member 271 does not
serve as the flame stabilizer.
Ninth Embodiment
[0273] FIG. 21 is a front view illustrating a combustion burner
according to a ninth embodiment of the invention. Furthermore, the
same reference sign will be given to the component having the same
function as that of the above-described embodiment, and the
detailed description thereof will not be repeated.
[0274] In the combustion burner of the ninth embodiment, as
illustrated in FIG. 21, the combustion burner 221 is equipped with
the fuel nozzle 251, the secondary air nozzle 252, and the tertiary
air nozzle 253 which are provided from the center side of the
combustion burner, and is equipped with the flame stabilizer 254.
Then, since the fuel gas flowing through the fuel nozzle 251 is
guided toward the axis center side of the fuel nozzle, a guide
member is provided so as to guide the fuel gas in a direction in
which the fuel gas is separated from the secondary air blowing from
the secondary air nozzle 252.
[0275] The guide member is disposed at the widened portions 261b
and 262b of the flame stabilizer 254 so as to face the inner wall
surface of the fuel nozzle 251. That is, in the flame stabilizer
254, the first flame stabilizing members 261 and 262 following the
horizontal direction and the second flame stabilizing members 263
and 264 following the vertical direction are disposed so as to
intersect one another, and the guide member is formed as notched
surfaces 261c, 262c, 263c, and 264c formed in the end portions of
the widened portions 261b and 262b of the respective flame
stabilizing members 261, 262, 263, and 264. The respective notched
surfaces 261c, 262c, 263c, and 264c are formed in a tapered shape
in which an inclined surface is formed at both sides of each end
portion when viewed from the front sides of the respective flame
stabilizing members 261, 262, 263, and 264.
[0276] Accordingly, in the combustion burner 221, since the notched
surfaces 261c, 262c, 263c, and 264c are formed as the guide member
at the end portions of the respective flame stabilizing members
261, 262, 263, and 264 of the flame stabilizer 254, the fuel gas
flowing through the fuel nozzle 251 is guided by the respective
notched surfaces 261c, 262c, 263c, and 264c toward the axis center
side of the fuel nozzle, that is, the inside of the respective
flame stabilizing members 261, 262, 263, and 264 in the
longitudinal direction. That is, when the fuel gas passes through
the vicinity of the notched surfaces 261c, 262c, 263c, and 264c of
the respective flame stabilizing members 261, 262, 263, and 264,
the front end surface sides of the respective flame stabilizing
members 261, 262, 263, and 264 have a negative pressure.
Accordingly, the fuel gas is guided to the negative pressure zone,
and hence the flow indicated by the arrow of FIG. 21 occurs.
[0277] Then, the fuel gas blowing into the furnace by the fuel
nozzle 251 is guided in a direction in which the fuel gas is
separated from the secondary air blowing from the secondary air
nozzle 252. For this reason, since the fuel gas is separated from
the secondary air of which the speed is faster than that of the
fuel gas, the inner flame stabilization using the flame stabilizer
254 may be performed. Further, since the fuel gas is separated from
the secondary air and the NOx production amount caused by the
mixture with the secondary air is reduced in the fuel gas.
[0278] In this way, in the combustion burner of the ninth
embodiment, there are provided the fuel nozzle 251 which may blow
the fuel gas obtained by mixing the pulverized coal with the
primary air and the secondary air nozzle 252 which may blow the
secondary air from the outside of the fuel nozzle 251. Also, the
flame stabilizer 254 is provided at the front end portion of the
fuel nozzle 251 so as to be near the axis center, and as the guide
member that guides the fuel gas flowing through the fuel nozzle 251
toward the axis center side of the fuel nozzle, the notched
surfaces 261c, 262c, 263c, and 264c are provided at the end
portions of the respective flame stabilizing members 261, 262, 263,
and 264 of the flame stabilizer 254.
[0279] Accordingly, the fuel gas flowing through the fuel nozzle
251 is guided by the notched surfaces 261c, 262c, 263c, and 264c
toward the axis center side of the fuel nozzle 251, that is, the
center side of the flame stabilizer 254, and hence the appropriate
flow of the fuel gas inside the fuel nozzle 251 may be realized. As
a result, the inner flame stabilization performance using the flame
stabilizer 254 may be improved. Further, since the guide member is
formed by forming the notched surfaces 261c, 262c, 263c, and 264c
at the end portion of the flame stabilizer 254, the apparatus may
be simplified.
[0280] Furthermore, in the ninth embodiment, the guide member is
formed as the notched surfaces 261c, 262c, 263c, and 264c which are
formed at the end portions of the flame stabilizing members 261,
262, 263, and 264 in the longitudinal direction so as to have a
tapered shape, but the invention is not limited to the shape. For
example, the notched surfaces may be formed by notching only one
side of the end portions of the flame stabilizing members 261, 262,
263, and 264 in the longitudinal direction or the notched portions
may be formed by cutting the flame stabilizing members 261, 262,
263, and 264 in a direction perpendicular to the longitudinal
direction thereof so as to be separated from the inner wall surface
of the fuel nozzle 251. Further, the respective notched surfaces
261c, 262c, 263c, and 264c may be formed in a shape in which the
widths thereof are widened at the downstream side in the fuel gas
flowing direction as in the widened portions 261b and 262b.
Tenth Embodiment
[0281] FIG. 22 is a front view illustrating a combustion burner
according to a tenth embodiment of the invention. Furthermore, the
same reference sign will be given to the component having the same
function as that of the above-described embodiment, and the
detailed description thereof will not be repeated.
[0282] In the combustion burner of the tenth embodiment, as
illustrated in FIG. 22, the combustion burner 221 is equipped with
the fuel nozzle 251, the secondary air nozzle 252, and the tertiary
air nozzle 253 which are provided from the center side of the
combustion burner, and is equipped with the flame stabilizer 254.
Then, since the fuel gas flowing through the fuel nozzle 251 is
guided toward the axis center side of the fuel nozzle, a guide
member is provided so as to guide the fuel gas in a direction in
which the fuel gas is separated from the secondary air blowing from
the secondary air nozzle 252.
[0283] The guide member is disposed as triangular plates 281, 282,
283, and 284 so as to be positioned at a position where the first
flame stabilizing members 261 and 262 intersect the second flame
stabilizing members 263 and 264. Specifically, the guide member is
disposed at the outside of the position where the widened portions
261b and 262b of the first flame stabilizing members 261 and 262
intersect the widened portions (not illustrated) of the second
flame stabilizing members 263 and 264, that is, the opposite side
to the axis center of the fuel nozzle 251. The respective
triangular plates 281, 282, 283, and 284 are formed in a triangular
shape by forming an inclined surface at the outside of each
intersected corner when viewed from the front sides of the
respective flame stabilizing members 261, 262, 263, and 264.
[0284] Accordingly, since the triangular plates 281, 282, 283, and
284 are disposed at the outside of the intersection points of the
respective flame stabilizing members 261, 262, 263, and 264 of the
flame stabilizer 54 in the combustion burner 221, the fuel gas
flowing through the fuel nozzle 251 is guided by the respective
triangular plates 281, 282, 283, and 284 toward the axis center
side of the fuel nozzle, that is, the center portions of the
respective flame stabilizing members 261, 262, 263, and 264. That
is, when the fuel gas passes through the vicinity of the respective
triangular plates 281, 282, 283, and 284, the front surface sides
of the respective triangular plates 281, 282, 283, and 284 have a
negative pressure.
[0285] Accordingly, the fuel gas is guided to the negative pressure
zone, and hence the flow indicated by the arrow of FIG. 22
occurs.
[0286] Then, the fuel gas blowing into the furnace by the fuel
nozzle 251 is guided in a direction in which the fuel gas is
separated from the secondary air blowing from the secondary air
nozzle 252. For this reason, since the fuel gas is separated from
the secondary air of which the speed is faster than that of the
fuel gas, the inner flame stabilization using the flame stabilizer
254 may be performed. Further, since the fuel gas is separated from
the secondary air and the NOx production amount caused by the
mixture with the secondary air is reduced in the fuel gas.
[0287] In this way, in the combustion burner of the tenth
embodiment, there are provided the fuel nozzle 251 which may blow
the fuel gas obtained by mixing the pulverized coal with the
primary air and the secondary air nozzle 252 which may blow the
secondary air from the outside of the fuel nozzle 251. Also, the
flame stabilizer 254 is provided at the front end portion of the
fuel nozzle 251 so as to be near the axis center, and as the guide
member that guides the fuel gas flowing through the fuel nozzle 251
toward the axis center side of the fuel nozzle, the triangular
plates 281, 282, 283, and 284 are disposed at the intersection
positions of the respective flame stabilizing members 261, 262,
263, and 264 of the flame stabilizer 254.
[0288] Accordingly, the fuel gas flowing through the fuel nozzle
251 is guided by the triangular plates 281, 282, 283, and 284
toward the axis center side of the fuel nozzle 251, that is, the
center side the flame stabilizer 254, and hence the appropriate
flow of the fuel gas inside the fuel nozzle 251 may be realized. As
a result, the inner flame stabilization performance using the flame
stabilizer 254 may be improved. Further, the flame stabilizer 254
is formed in a structure in which two first flame stabilizing
members 261 and 262 provided in the horizontal direction while
being parallel to each other in the vertical direction with a
predetermined gap therebetween and two second flame stabilizing
members 263 and 264 provided in the vertical direction while being
parallel to each other in the horizontal direction with a
predetermined gap therebetween are disposed so as to intersect one
another. Accordingly, since the flame stabilizer 254 is formed in a
double cross structure, the sufficient flame stabilizing function
may be ensured. Further, since the guide member is formed as the
triangular plates 281, 282, 283, and 284, the fuel gas flowing
through the fuel nozzle 251 may be effectively guided toward the
axis center side.
[0289] Furthermore, in the tenth embodiment, the guide member is
formed as the triangular plates 281, 282, 283, and 284, but the
invention is not limited to the shape. For example, the respective
triangular plates 281, 282, 283, and 284 may be formed in a shape
in which the widths thereof at the downstream side in the fuel gas
flowing direction are widened as in the widened portions 261b and
262b.
Eleventh Embodiment
[0290] FIG. 23 is a cross-sectional view illustrating a combustion
burner according to an eleventh embodiment of the invention, and
FIG. 24 is a cross-sectional view illustrating a modified example
of the combustion burner of the eleventh embodiment. Furthermore,
the same reference sign will be given to the component having the
same function as that of the above-described embodiment, and the
detailed description thereof will not be repeated.
[0291] In the combustion burner of the eleventh embodiment, as
illustrated in FIG. 23, the combustion burner 221 is equipped with
the fuel nozzle 251, the secondary air nozzle 252, and the tertiary
air nozzle 253 which are provided from the center side of the
combustion burner, and is equipped with a flame stabilizer 291.
Then, since the fuel gas flowing through the fuel nozzle 251 is
guided toward the axis center side of the fuel nozzle, a guide
member is provided so as to guide the fuel gas in a direction in
which the fuel gas is separated from the secondary air blowing from
the secondary air nozzle 252.
[0292] That is, the flame stabilizer 291 includes flame stabilizing
members 292 and 293 following the horizontal direction, and the
flame stabilizing members 292 and 293 include flat portions 292a
and 293a which are formed in a flat plate shape having a uniform
thickness and widened portions 292b and 293b which are integrally
formed with the front end portions of the flat portions 292a and
293a (the downstream end portions in the fuel gas flowing
direction). Each cross-section of the widened portions 292b and
293b is formed in an isosceles triangular shape, each width of the
widened portions is widened toward the downstream side in the fuel
gas flowing direction, and each front end thereof is formed as a
plane perpendicular to the fuel gas flowing direction.
[0293] Then, the guide member is formed by directing the front end
portions of the flame stabilizing members 292 and 293 toward the
axis center side of the fuel nozzle 251. That is, the flame
stabilizing members 292 and 293 are inclined with respect to the
axis center of the fuel nozzle 251 in a manner such that the
widened portions 292b and 293b formed at the front end portion
thereof are disposed so as to be close to each other compared to
the rear end portions of the flat portions 292a and 293a.
[0294] Accordingly, since the front end portions of the flame
stabilizing members 292 and 293 are disposed so as to be close to
each other at the flame stabilizer 291 inside the fuel nozzle 251
in the combustion burner 221, the fuel gas flowing through the fuel
nozzle 251 is guided by the flame stabilizing members 292 and 293
toward the axis center side. That is, since the front end portions
of the flame stabilizing members 292 and 293 are close to each
other, the fuel gas becomes fast between the flame stabilizing
members 292 and 293 and becomes low between the fuel nozzle 251 and
the flame stabilizing members 292 and 293. Thus, the fuel gas is
guided toward the axis center of the fuel nozzle 251 on the
whole.
[0295] Then, the fuel gas blowing into the furnace by the fuel
nozzle 251 is guided in a direction in which the fuel gas is
separated from the secondary air blowing from the secondary air
nozzle 252. For this reason, since the fuel gas is separated from
the secondary air of which the speed is faster than that of the
fuel gas, the inner flame stabilization using the flame stabilizer
291 is appropriately performed. Further, since the fuel gas is
separated from the secondary air and the NOx production amount
caused by the mixture with the secondary air is reduced in the fuel
gas.
[0296] In this case, the inclination angles of the flame
stabilizing members 292 and 293 constituting the flame stabilizer
291 may be adjusted. That is, as illustrated in FIG. 24, the flame
stabilizing members 292 and 293 are supported so as to be rotatable
up and down by support shafts 295 and 296 following the horizontal
direction perpendicular to the fuel gas flowing direction of the
fuel nozzle 251, and are rotatable by a driving device 297. That
is, the inclination angles of the flame stabilizing members 292 and
293 may be individually adjusted by the driving device 297.
[0297] Accordingly, the optimal blowing state of the fuel gas may
be maintained in a manner such that the driving device 297
individually adjusts the angles of the flame stabilizing members
292 and 293 based on, for example, the characteristics or the speed
of the fuel gas, the speed of the secondary air, and the combustion
state inside the furnace 211.
[0298] In this way, in the combustion burner of the eleventh
embodiment, there are provided the fuel nozzle 251 which may blow
the fuel gas obtained by mixing the pulverized coal with the
primary air and the secondary air nozzle 252 which may blow the
secondary air from the outside of the fuel nozzle 251. Also, the
flame stabilizer 291 is provided at the front end portion of the
fuel nozzle 251 so as to be near the axis center, and as the guide
member that guides the fuel gas flowing through the fuel nozzle 251
toward the axis center side of the fuel nozzle, the flame
stabilizing members 292 and 293 of the flame stabilizer 291 are
disposed so that the front end portions thereof face the axis
center side of the fuel nozzle 251.
[0299] Accordingly, the fuel gas flowing through the fuel nozzle
251 is guided by the inclined flame stabilizing members 292 and 293
toward the axis center side of the fuel nozzle 251, that is, the
center side of the flame stabilizer 291, and hence the appropriate
flow of the fuel gas inside the fuel nozzle 251 may be realized. As
a result, the inner flame stabilization performance using the flame
stabilizer 291 may be improved. Further, since the guide member is
formed by the arrangement of the flame stabilizing members 292 and
293 of the flame stabilizer 291, the structure may be
simplified.
[0300] Further, in the combustion burner of the eleventh
embodiment, it is possible to individually adjust the inclination
angles of the flame stabilizing members 292 and 293 by the driving
device 297. Accordingly, the optimal blowing state of the fuel gas
may be maintained by changing the angles of the flame stabilizing
members 292 and 293 based on, for example, the characteristics or
the speed of the fuel gas, the speed of the secondary air, and the
combustion state inside the furnace 211.
[0301] Furthermore, in the above-described respective embodiments,
the configurations of the flame stabilizers 254 and 291 have been
described by various examples, but the invention is not limited to
the above-described configurations. That is, the burner of the
invention is used to realize the inner flame stabilization. Then,
the flame stabilizer may be provided toward the axis center side of
the fuel nozzle 251 instead of the inner wall surface of the fuel
nozzle 251, the number or the position of the flame stabilizing
members may be appropriately set, and the flame stabilizing member
may be separated from the inner wall surface of the fuel nozzle
251. Further, the configuration of the guide member has been
described by various examples, but the configuration is not limited
to the above-described configuration. That is, the fuel gas inside
the fuel nozzle may be guided toward the axis center side by the
guide member.
[0302] Further, the flame stabilizer of the invention is equipped
with the widened portion having a triangular cross-sectional shape,
but the invention is not limited to the shape. That is, the shape
may be a square shape and the widened portion may not be
provided.
[0303] Further, in the above-described respective embodiments, the
guide member of the invention is provided in the inner wall surface
of the fuel nozzle or the flame stabilizer, but a separate member
may be provided between the inner wall surface of the fuel nozzle
and the flame stabilizer. For example, the guide member may be
formed in a square or argyle frame shape by providing the guide
member between the inner wall surface of the fuel nozzle and the
flame stabilizer in a direction parallel to or intersecting the
flame stabilizer.
[0304] Further, in the above-described respective embodiments, four
combustion burners 221, 222, 223, 224, and 225 provided in the wall
surface of the furnace 211 are disposed at five stages in the
vertical direction as the combustion device 212, but the invention
is not limited to the configuration. That is, the combustion burner
may be disposed at the corner instead of the wall surface. Further,
the combustion device is not limited to the turning combustion
type, but may be a front combustion type in which the combustion
burner is disposed in one wall surface or an opposed combustion
type in which the combustion burners are disposed in two wall
surfaces so as to be opposed to each other.
Twelfth Embodiment
[0305] Hitherto, as the solid-fuel-combustion boiler, there is
known, for example, a pulverized-coal-combustion boiler which burns
pulverized coal (coal) as solid fuel. In such a
pulverized-coal-combustion boiler, two kinds of combustion types,
the turning combustion boiler and the wall-combustion boiler are
known.
[0306] Among these, in the pulverized-coal-combustion turning
combustion boiler, secondary air input ports for inputting the
secondary air are provided at the upper and lower sides of the
primary air input from the coal-combustion burner (the
solid-fuel-combustion burner) along with pulverized coal as fuel so
as to adjust the flow rate of the secondary air around the
coal-combustion burner. Since the air amount of the primary air is
needed to transport the pulverized coal as fuel, the air amount is
defined in the roller milling device that obtains the pulverized
coal by milling coal. Then, since the secondary air blows by the
amount necessary for forming the entire flame inside the turning
combustion boiler, the secondary air amount of the turning
combustion boiler is substantially obtained by subtracting the
primary air amount from the entire air amount necessary for the
combustion of the pulverized coal. Further, in the burner of the
turning combustion boiler, the outer flame stabilization is
performed which strengths the ignition of the outer periphery of
the flame by the separation of the pulverized coal according to the
lean and rich levels.
[0307] On the contrary, in the burner of the opposed wall-fired
boiler, for example, as disclosed in Patent Literature 2, the
secondary air and the tertiary air are introduced to the outer
peripheral side of the primary air (the supply of the pulverized
coal) so as to finely adjust the air introduction amount. That is,
generally, a burner with an outer flame stabilization structure is
provided in which a flame stabilizing mechanism (for a front end
angle adjustment operation, a turning operation, or the like) is
provided at the outer periphery of the burner formed in a circular
shape when viewed from the inside of the furnace and an input port
for the secondary air or the tertiary air is concentrically
provided so as to be near the outer periphery of the burner.
[0308] Further, in the conventional pulverized-coal-combustion
burner, for example, as disclosed in Patent Literature 3, the
ignition of the outer periphery of the flame is further
strengthened by the separation of the pulverized coal to the outer
periphery according to the lean and rich levels. Further, even in
Patent Literature 4, the outer peripheral flame stabilizer and the
flame stabilizer formed in a split structure are disclosed. In this
case, the outer peripheral flame stabilizer is used for a primary
function and the split structure is used for a secondary
function.
[0309] Incidentally, in the conventional turning combustion boiler,
since the secondary air input ports for inputting the secondary air
are respectively integrally formed at the upper and lower sides of
the coal-combustion burner, the amount of the secondary air input
from the secondary air input port may not be finely adjusted. For
this reason, a hot oxygen remaining zone is formed at the outer
periphery of the flame. Thus, the hot oxygen remaining zone is
particularly wide in a zone where the secondary air concentrates,
and hence the NOx production amount increases.
[0310] Further, in the conventional coal-combustion burner,
generally, the outer periphery of the burner is equipped with the
flame stabilizing mechanism (for a front end angle adjustment
operation, a turning operation, or the like), and a port for
inputting the secondary air (or the tertiary air) is provided near
the outer periphery. For this reason, the ignition occurs at the
outer periphery of the flame, so that a large amount of oxygen is
mixed with the outer periphery of the flame. As a result, the
combustion at the outer periphery of the flame occurs in a state
where the oxygen concentration in the hot oxygen remaining zone of
the outer periphery of the flame is high, so that NOx is produced
at the outer periphery of the flame. In this way, the NOx produced
in the hot oxygen remaining zone of the outer periphery of the
flame passes through the outer periphery of the flame, the
reduction is later than that of the inside of the flame, which
causes NOx from the coal-combustion boiler.
[0311] Meanwhile, even in the opposed wall-fired boiler, since the
ignition occurs at the outer periphery of the flame by the swirl,
NOx is produced as in the outer periphery of the flame.
[0312] Due to these circumstances, in the solid-fuel-combustion
burner and the solid-fuel-combustion boiler that burns the
pulverized solid fuel as in the conventional coal-combustion burner
and the conventional coal-combustion boiler, it is desirable to
reduce the finally NOx production amount of NOx discharged from the
additional air input unit by suppressing the hot oxygen remaining
zone formed at the outer periphery of the flame.
[0313] The invention is made in view of the above-described
circumstances, and it is an object of the invention to provide a
solid-fuel-combustion burner and a solid-fuel-combustion boiler
capable of reducing a final NOx production amount of NOx discharged
from an additional air input unit by suppressing (weakening) a hot
oxygen remaining zone formed in an outer periphery of a flame.
[0314] Hereinafter, one embodiment of the solid-fuel-combustion
burner and the solid-fuel-combustion boiler according to the
invention will be described by referring to the drawings.
Furthermore, in the embodiment, a turning combustion boiler with a
solid-fuel-combustion burner that uses pulverized coal (coal as
pulverized solid fuel) will be described as an example of the
solid-fuel-combustion burner and the solid-fuel-combustion boiler,
but the invention is not limited thereto.
[0315] A turning combustion boiler 310 illustrated in FIGS. 27 to
29 inputs air into a furnace 311 in plural stages so as to set a
zone from a burner 312 to an additional air input unit
(hereinafter, referred to as a "AA part") 314 as a reduction
atmosphere, whereby the NOx of the flue gas decreases.
[0316] The reference sign 320 of the drawings indicates a
solid-fuel-combustion burner that inputs the pulverized coal (the
pulverized solid fuel) and the air, and the reference sign 315
indicates an additional air input nozzle that ejects additional
air. For example, as illustrated in FIG. 27, the
solid-fuel-combustion burner 320 is connected with a pulverized
coal fuel-air mixture transportation pipe 316 that transports the
pulverized coal by the primary air and an air blowing duct 317 that
supplies the secondary air, and the additional air input nozzle 315
is connected with the air blowing duct 317 that supplies the
secondary air.
[0317] In this way, the turning combustion boiler 310 employs a
turning combustion type in which the solid-fuel-combustion burner
320 for inputting the air and the pulverized coal (coal) of the
pulverized fuel into the furnace 311 is formed as the turning
combustion type burner 312 disposed at each corner of each
stage.
[0318] The solid-fuel-combustion burner 320 illustrated in FIGS.
25A to 25B include a pulverized coal burner (fuel burner) 321 which
inputs the pulverized coal and the air and secondary air input
ports 330 which are respectively disposed at the upper and lower
sides of the pulverized coal burner 321.
[0319] For example, as illustrated in FIG. 26, each secondary air
input port 330 includes a damper 340 capable of adjusting an
opening degree as a flow rate adjusting unit provided for each of
the secondary air supply lines branched from the air blowing duct
317 in order to adjust the air flow amount for each port.
[0320] The pulverized coal burner 321 includes a rectangular coal
primary port 322 which inputs the pulverized coal transported by
the primary air and a coal secondary port 323 which is provided so
as to surround the coal primary port 322 and inputs a part of the
secondary air. Furthermore, as illustrated in FIG. 26, the coal
secondary port 323 also includes a damper 340 capable of adjusting
an opening degree as a flow rate adjusting unit. Furthermore, the
coal primary port 322 may have a circular shape or an oval
shape.
[0321] Split members 324 are disposed in a plurality of directions
at the front side of the passage of the pulverized coal burner 321,
that is, the front side of the passage of the coal primary port
322, and are fixed by support members (not illustrated). For
example, as illustrated in FIG. 25A, two split members 324 are
disposed in a lattice shape with a predetermined gap therebetween
so that one split member is positioned in each of the up and down
direction and the left and right direction at the outlet opening
portion of the coal primary port 322.
[0322] That is, two split members 324 are formed in a cross type in
a manner such that the split members are disposed in two different
directions of the up and down direction and the left and right
direction. Here, the outlet opening portion of the coal primary
port 322 of the pulverized coal burner 321 is finely divided
(divided into four segments), but the number of the split members
324 may be plural numbers in each of the up and down direction and
the left and right direction.
[0323] Further, a pressure loss is large in a portion sandwiched by
the split members 324, and the flow velocity of the ejection port
decreases, so that the inner ignition is further promoted.
[0324] The split members 324 with such a configuration suppress the
hot oxygen remaining zone H formed in the outer periphery of the
flame F, and effectively reduces the final NOx production amount of
NOx discharged from the AA part 314.
[0325] The split members 324 employ, for example, the
cross-sectional shape illustrated in FIGS. 30A to 30D, and hence
smoothly divide the flow of the pulverized coal and the air so that
the flow is disturbed.
[0326] Each split member 324 illustrated in FIG. 30A has a
triangular cross-sectional shape. The triangular shape illustrated
in the drawing is an equilateral-triangular shape or an isosceles
triangular shape, and one outlet-side edge facing the inside of the
furnace 311 is disposed so as to intersect the direction in which
the pulverized coal and the air flow. In other words, an
arrangement is employed in which one corner forming the triangular
cross-section is disposed so as to face the direction in which the
pulverized coal and the air flow.
[0327] A split member 324A illustrated in FIG. 30B has a
substantially T-shaped cross-section, and a surface substantially
perpendicular to the direction in which the pulverized coal and the
air flow is disposed at the outlet side facing the inside of the
furnace 311. Furthermore, for example, as illustrated in FIG. 30C,
a split member 324A' having a trapezoidal cross-sectional shape may
be provided by deforming the substantially T-shaped
cross-section.
[0328] Further, a split member 324B illustrated in FIG. 30D has a
substantially L-shaped cross-section. That is, in a case where a
cross-section obtained by cutting out a part of the substantial
T-shape is particularly disposed in the left and right (horizontal)
direction, when a substantial L-shape is formed by removing an
upper convex portion, it is possible to prevent the deposit of the
pulverized coal to the split member 324B. Furthermore, when a lower
convex portion increases in size by the removable amount of the
upper convex portion, the separation performance necessary for the
split member 324B may be ensured.
[0329] However, the cross-sectional shape of the split member 324
or the like is not limited to the example illustrated in the
drawings, and may be substantially formed in, for example, a
Y-shape.
[0330] In the solid-fuel-combustion burner 320 with such a
configuration, the split member 324 which is provided near the
center of the outlet opening of the pulverized coal burner 321
divides the passage of the pulverized coal and the air so as to
disturb the flow therein, and forms a recirculation zone at the
front side (the downstream side) of the split member 324. Thus, the
split member serves as an inner flame stabilization mechanism.
[0331] In general, the conventional solid-fuel-combustion burner
320 ignites the pulverized coal of the fuel by the radiation of the
outer periphery of the flame. When the pulverized coal is ignited
by the outer periphery of the flame, NOx is produced in the hot
oxygen remaining zone H (see FIG. 25B) of the outer periphery of
the flame where hot oxygen remains, and hence the NOx discharge
amount increase while the reduction is not sufficiently
performed.
[0332] However, since the split member 324 serving as the inner
flame stabilization mechanism is provided, the pulverized coal is
ignited at the inside of the flame. For this reason, NOx is
produced at the inside of the flame, and the NOx produced at the
inside of the flame contains a large amount of hydrocarbons having
a reduction action. For this reason, the reduction is promptly
performed inside the flame which does not have sufficient air.
Accordingly, the solid-fuel-combustion burner 320 is provided in a
structure in which the flame stabilization performed by the flame
stabilizer at the outer periphery of the flame is stopped, that is,
the flame stabilizing mechanism is not provided at the outer
periphery of the burner, and hence the production of NOx at the
outer periphery of the flame may be suppressed.
[0333] Particularly, when a cross type is employed in which the
split members 324 are disposed in a plurality of directions, the
intersection portion obtained by intersecting the split members 324
in different directions may be easily provided near the center of
the outlet opening of the pulverized coal burner 321. When the
intersection portion exists near the center of the outlet opening
of the pulverized coal burner 321, the passage of the pulverized
coal and the air is divided into plural segments near the center of
the outlet opening of the pulverized coal burner 321, and hence the
flow is disturbed when the flow is divided into plural flows.
[0334] That is, when the split members 324 exist in one direction
of the left and right direction, the dispersion or the ignition of
the air at the center portion is delayed, so that a zone exists in
which air is locally and extremely insufficient. Thus, the unburned
combustible content increases. However, in a cross type in which
the intersection portion is formed by disposing the split members
324 in a plurality of directions, the mixing of the air at the
inside of the flame is promoted and the ignition surface is finely
divided. As a result, the unburned combustible content may be
reduced.
[0335] In other words, when the split members 324 are disposed so
as to form the intersection portion, the mixing and the dispersion
of the air are promoted to the inside of the flame, so that the
ignition surface is finely divided. Thus, the ignition position
exists near the center portion (the axis center portion) of the
flame, and hence the unburned combustible content of the pulverized
coal is reduced. That is, since oxygen easily enters the center
portion of the flame, the inner ignition is effectively performed.
Accordingly, the reduction is promptly performed at the inside of
the flame, and hence the NOx production amount is reduced.
[0336] As a result, it is possible to more easily suppress the
production of NOx at the outer periphery of the flame by using the
solid-fuel-combustion burner 320 that does not have the flame
stabilizer at the outer periphery of the flame by stopping the
flame stabilization using the flame stabilizer provided at the
outer periphery of the flame.
[0337] In the split members 324 disposed in a plurality of
directions, in the embodiment, when the width of the split member
324 viewed from the inside of the furnace is set as the splitter
width W, the split members having different splitter widths W for
the respective directions are disposed in a cross type.
[0338] For example, in configuration example of the cross type
illustrated in FIG. 25A, the outlet opening portion of the coal
primary port 322 is equipped with one split member (hereinafter,
referred to as a "vertical splitter") 324V disposed in the up and
down direction and one split member (hereinafter, referred to as a
"horizontal splitter") 324H disposed in the left and right
direction.
[0339] Then, the splitter width Wv of the vertical splitter 324V is
larger and wider than the splitter width Wh of the horizontal
splitter 324H (Wv >Wh), but an inverse configuration may be
set.
[0340] That is, the split member 324 illustrated in the drawings
strengthens the vertical splitter function, but relatively degrades
the horizontal splitter function. For this reason, a structure is
used in which the splitter width Wv of the vertical splitter 324V
is set to be larger than the splitter width Wh of the horizontal
splitter 324H. This configuration is prepared to handle a change in
the angle of the fuel burner 321 of which the angle may be
changed.
[0341] For example, as illustrated in FIG. 25B, the fuel burner 321
may appropriately change the burner angle (the nozzle angle)
.alpha. in the up and down direction so as to adjust the
temperature of the steam produced by the turning combustion boiler
310 to a desired value.
[0342] However, even when the burner angle .alpha. changes, the
angle of the split member 324 that is fixed and supported to an
appropriate position does not change while being interlocked with
the fuel burner 321. For this reason, the positional relation
between the fuel burner 321 and the split member 324 changes in
response to a change in the burner angle .alpha..
[0343] When the burner angle .alpha. changes in the up and down
direction, the positional relation between the pulverized coal flow
and the horizontal splitter 324H changes when inputting the
pulverized coal and the primary air. Since a change in the
positional relation is largely influenced as the splitter width Wh
of the horizontal splitter 324H increases, the burner performance
is eventually influenced, and hence it is difficult to uniformly
maintain the burner performance. Accordingly, it is desirable to
prevent the burner performance from being influenced even when the
burner angle .alpha. of the fuel burner 321 changes.
[0344] Therefore, in the embodiment, the split member 324 that
strengthens the vertical splitter function by relatively increasing
the splitter width Wv of the vertical splitter 324V may narrow the
splitter width Wh of the horizontal splitter 324H to the minimally
necessary width, and hence suppress a change in the positional
relation caused by a change in the burner angle .alpha. to the
minimal value.
[0345] Accordingly, since the split member 324 is formed in a cross
type in which the splitters exist in both directions of the up and
down direction and the left and right direction by remaining the
horizontal splitter 324H having a small splitter width W, it is
possible to maintain a state where the mixing of the air is
promoted and the ignition surface is finely divided. For this
reason, in the split member 324, the air may easily enter the
center portion of the flame. As a result, it is possible to
minimally suppress a change in the positional relation caused by a
change in the burner angle .alpha. while keeping the advantage of
the cross type in which the unburned combustible content may be
reduced by the promotion of the ignition of the center portion, and
to substantially uniformly maintain the burner performance.
[0346] Further, in a case of the turning combustion type in which
the secondary air input port 330 is disposed in the up and down
direction of the pulverized coal burner 321, the splitter width Wh
of the horizontal splitter 324H is set to be larger and wider than
the splitter width Wv of the vertical splitter 324V (Wh>Wv).
[0347] This is because the splitter function is strengthened when
the splitter width Wv of the vertical splitter 324V is larger than
the necessary value and the splitter easily becomes the ignition
source of the pulverized coal.
[0348] Moreover, regarding the ignition in the vicinity of both
upper and lower end portions of the vertical splitter 324V, since
the ignition source is close to the secondary air input port 330,
the ignition at the outer periphery of the flame easily and
directly interferes with the secondary air. As a result, a large
amount of air is mixed with the pulverized coal that is ignited at
the outer periphery of the flame using the vertical splitter 324V
as the ignition source. Accordingly, NOx is produced at the hot
oxygen remaining zone H of the outer periphery of the flame where
hot oxygen remains. The NOx remains without sufficient reduction,
and increases the final NOx discharge amount.
[0349] However, when the splitter width Wh of the horizontal
splitter 324H is set to a large width so as to strengthen the
splitter function of the horizontal splitter 324H, the ignition
source in the vicinity of the secondary air input port 330 existing
at the upper and lower sides of the pulverized coal burner 321
decreases in size. That is, the downstream side of the wide
horizontal splitter 324H is equipped with a negative pressure zone
as a large recirculation zone, and hence a strong splitter function
is exhibited. For this reason, the flow of the pulverized coal and
the primary air may easily concentrate on the center portion in the
up and down direction.
[0350] As a result, the ignition occurs at the outer periphery of
the flame by using the vicinity of both end portions of the
vertical splitter 324V as the ignition source, and the amount of
the pulverized coal mixed with a large amount of air largely
decreases. Meanwhile, the mixing and the dispersion of the
pulverized coal and the primary air are promoted to the inside of
the flame, so that the air (oxygen) may easily enter the center
portion of the flame. As a result, since the inner ignition is
effectively performed, the prompt reduction occurs at the inside of
the flame, and hence the NOx production amount is reduced.
[0351] In this case, since the cross type split members 324 exist
in the up and down direction and the left and right direction by
leaving the vertical splitter 324V, that is, forming the vertical
splitter 324V with the small splitter width Wv, the mixing of the
air is promoted and the ignition surface is finely divided. For
this reason, in the solid-fuel-combustion burner 320 with the cross
type split members 324, the air may easily enter the center portion
of the flame, and hence the unburned combustible content may be
reduced by the promotion of the ignition of the center portion.
Thirteenth Embodiment
[0352] Next, a solid-fuel-combustion burner according to a
thirteenth embodiment of the invention will be described. In the
embodiment, the split members 324 provided in the
solid-fuel-combustion burner 320 are formed as the split members
324 that are disposed in a plurality of directions and having
different splitter widths W. Furthermore, the splitter width W of
the center portion of three or more split members disposed in the
same direction is set to a large width, and the widths of the
peripheral portions are relatively narrowed.
[0353] In the split members 324 with such a configuration, since
the splitter with a large width is disposed at the center portion
of the solid-fuel-combustion burner 320, the splitter function of
the center portion is strengthened, and hence the inner ignition
may be strengthened while preventing the outer ignition.
[0354] That is, since the solid-fuel-combustion burner 320 of the
embodiment includes the cross type split members 324 of which the
center portion has a large width, the existence of the splitter
serving as the ignition source at the outer peripheral portion of
the pulverized coal burner 321 is suppressed as minimal as
possible, so that the outer ignition may be prevented or
suppressed. Further, since the splitter function of the center
portion is strengthened, the air easily enters the center portion
of the flame. As a result, the unburned combustible content may be
reduced by the promotion of the ignition of the center portion.
[0355] Incidentally, in the above-described configuration example,
three splitters are disposed in each of the up and down direction
and the left and right direction, and only one splitter disposed at
the center portion in the up and down direction and the left and
right direction has a large width. However, not only the number of
the splitters but also the number or the position of the wide
splitter is not limited to the invention.
[0356] For example, a configuration may be employed in which four
splitters are disposed in the up and down direction and the left
and right direction and two splitters disposed at the center
portions in the up and down direction and the left and right
direction have a large width. Further, both splitters disposed at
the center portions in the up and down direction and the left and
right direction do not have a large width. For example, only the
splitter member disposed at the center portion in the up and down
direction or the left and right direction may have a large width.
Accordingly, a configuration is also included in which three or
more splitters are disposed in one of a plurality of directions so
as to have a large width at the center portion and one splitter
having a wide width or a narrow width or one splitter having a
narrow width is disposed in the other direction.
Fourteenth Embodiment
[0357] Next, a solid-fuel-combustion burner according to a
fourteenth embodiment of the invention will be described by
referring to FIGS. 31A and 31B. Furthermore, the same reference
sign will be given to the same component as that of the
above-described embodiment, and the repetitive description thereof
will not be repeated. In the embodiment, the split members 324 that
are provided in the solid-fuel-combustion burner 320A so as to
guide the flow of the pulverized coal and the primary air to the
inside of the center portion of the flame (the axis center side)
include a shielding member that is attached to the intersection
corner between the splitters disposed in a plurality of directions.
That is, in order to strengthen the inner flame stabilization or to
increase the ignition surface of the inside of the flame by further
improving the function of the split members 324, the shielding
member that reduces the passage sectional area is provided in at
least one position of the intersection corner formed by
intersecting the split members 324 as the function strengthening
member of the split members 324.
[0358] As the shielding member, for example, a triangular plate 350
is desirable which is attached to the split members 324 so as to
block the intersection center portion side of the intersection
corner. Then, the opening area of the coal primary port 322 viewed
from the inside of the furnace, that is, the passage sectional area
of the pulverized coal and the primary air decreases by the amount
corresponding to the area of the triangular plate 350. The
triangular plate 350 decreases the passage sectional area of the
pulverized coal and the primary air, and increases the ignition
surface of the inside of the flame. Also, the triangular plate has
a function of guiding the flow of the pulverized coal and the
primary air toward the center portion.
[0359] In other words, the triangular plate 350 is a shielding
member that is formed at the downstream side of the split member
324 so as to increase a negative pressure zone as a recirculation
zone, and may strengthen the flame stabilization effect of the
split member 324.
[0360] Accordingly, the shielding member may be provided in at
least one position of four intersection corners formed at the
intersection portions of the splitters 324H and 324V intersecting
each other in the up and down direction and the left and right
direction.
[0361] Further, the shielding member is not limited to the
triangular plate (the triangular plate member) 350 illustrated in
FIG. 32A. For example, a plate member may be formed with a shape
formed by 1/4 of the circular or oval shape. Moreover, for example,
as in a triangular pyramid 350A illustrated in FIG. 32B, an
inclined surface may be provided so as to guide a flow outward and
form a recirculation zone.
[0362] In this way, when the shielding member such as the
triangular plate 350 or the triangular pyramid 350A is provided at
the intersection portions of the splitters 324H and 324V, the
function of the split member 324 is further improved. Accordingly,
the ignition surface of the inside of the flame may be increased or
the inner flame stabilization may be strengthened.
[0363] According to the solid-fuel-combustion burner and the
solid-fuel-combustion boiler of the above-described embodiments, it
is possible to reduce the final NOx production amount of NOx
discharged from the AA part 314 by suppressing the hot oxygen
remaining zone H formed at the outer periphery of the flame F.
[0364] Furthermore, the invention is not limited to the
above-described embodiments. For example, the pulverized solid fuel
is not limited to the pulverized coal, and may be appropriately
modified without departing from the spirit of the invention.
Fifteenth Embodiment
[0365] Incidentally, in the conventional coal-combustion burner,
generally, the outer periphery of the burner is equipped with the
flame stabilizing mechanism (for a front end angle adjustment
operation, a turning operation, or the like), and the secondary air
(or tertiary air) input port is provided near the outer periphery.
For this reason, the ignition occurs at the outer periphery of the
flame, and hence a large amount of air is mixed at the outer
periphery of the flame. As a result, the combustion at the outer
periphery of the flame occurs at a high temperature state in which
the oxygen concentration at the hot oxygen remaining zone of the
outer periphery of the flame is high. Accordingly, NOx is produced
at the outer periphery of the flame. In this way, since the NOx
produced at the hot oxygen remaining zone of the outer periphery of
the flame passes through the outer periphery of the flame, the
reduction is later than that of the inside of the flame, which
causes the production of the NOx from the coal-combustion
boiler.
[0366] Meanwhile, even in the opposed wall-fired boiler, the
ignition occurs at the outer periphery of the flame by the swirl,
and hence NOx is produced as in the outer periphery of the
flame.
[0367] Due to these circumstances, in the solid-fuel-combustion
burner and the solid-fuel-combustion boiler that burns the
pulverized solid fuel as in the conventional coal-combustion burner
and the conventional coal-combustion boiler, it is desirable to
reduce the final NOx production amount of NOx discharged from the
additional air input unit by suppressing the hot oxygen remaining
zone formed at the outer periphery of the flame.
[0368] The invention is made in view of the above-described
circumstance, and it is an object of the invention to provide a
solid-fuel-combustion burner and a solid-fuel-combustion boiler
capable of reducing a final NOx production amount of NOx discharged
from an additional air input unit by suppressing (weakening) the
hot oxygen remaining zone formed at the outer periphery of the
flame.
[0369] Hereinafter, one embodiment of the solid-fuel-combustion
burner and the solid-fuel-combustion boiler according to the
invention will be described by referring to the drawings.
Furthermore, in the embodiment, a turning combustion boiler with a
solid-fuel-combustion burner using pulverized coal (coal as
pulverized solid fuel) as fuel will be described as an example of
the solid-fuel-combustion burner and the solid-fuel-combustion
boiler, but the invention is not limited thereto.
[0370] A turning combustion boiler 410 illustrated in FIGS. 35 to
37 inputs air into the furnace 411 in plural stages so that the
zone from the burner 412 to the additional air input unit
(hereinafter, referred to as an "AA part") 414 becomes a reduction
atmosphere. In this way, NOx in the flue gas may be decreased.
[0371] The reference sign 420 of the drawings indicate a
solid-fuel-combustion burner that inputs pulverized coal
(pulverized solid fuel) and air, and the reference sign 415
indicates an additional air input nozzle that inputs additional
air. For example, as illustrated in FIG. 35, the
solid-fuel-combustion burner 420 is connected with a pulverized
coal fuel-air mixture transportation pipe 416 that transports the
pulverized coal by the primary air and an air blowing duct 417 that
supplies the secondary air, and an additional air input nozzle 415
is connected with the air blowing duct 417 that supplies the
secondary air.
[0372] In this way, the turning combustion boiler 410 employs a
turning combustion type in which the solid-fuel-combustion burner
420 that inputs the air and the pulverized coal (coal) of the
pulverized fuel into the furnace 411 is formed as the turning
combustion type burner 412 that is disposed at each corner of each
stage and one or plural swirl flames are generated at each
stage.
[0373] The solid-fuel-combustion burner 420 illustrated in FIGS.
33A and 33B include a pulverized coal burner (fuel burner) 421 that
inputs the pulverized coal and the air and a coal secondary port
that ejects the secondary air from the outer periphery of the
pulverized coal burner 421. In the embodiment, the secondary air
port that ejects the secondary air from the outer periphery of the
pulverized coal burner 421 includes secondary air input ports 430
respectively disposed at the upper and lower sides of the
pulverized coal burner 421 and a coal secondary port 423. For
example, as illustrated in FIG. 34, in order to adjust the air flow
rate for each port, the secondary air input port 430 includes a
damper 440 which is provided as a flow rate adjusting unit for each
secondary air supply line branched from the air blowing duct 417 so
as to adjust the opening degree thereof.
[0374] The pulverized coal burner 421 includes a rectangular coal
primary port 422 which inputs the pulverized coal transported by
the primary air and a coal secondary port 423 which is provided so
as to surround the coal primary port 422 and inputs a part of the
secondary air. Furthermore, as illustrated in FIG. 34, even the
coal secondary port 423 includes the damper 440 as the flow rate
adjusting unit capable of adjusting the opening degree.
Furthermore, the coal primary port 422 may be formed in a circular
or oval shape.
[0375] A split member 424 is disposed at the front side of the
passage of the pulverized coal burner 421, that is, the front side
of the passage of the coal primary port 422, and is fixed by a
support member (not illustrated). For example, as illustrated in
FIG. 33A, one split member 424 is disposed in the horizontal
direction so as to be substantially positioned at the center
position in the up and down direction at the outlet opening portion
of the coal primary port 422, and both end portions thereof in the
horizontal (left and right) direction are partially removed so as
to be formed as removing portions 424a. Furthermore, in FIG. 33A,
the removing portions 424a are depicted by a dashed line.
[0376] In this case, as illustrated in FIGS. 33A and 33B, when the
passage width of the pulverized coal burner 421, that is, the
passage width (the passage width from the axis center) of the coal
primary port 422 is denoted by L1, the length (the length from the
axis center) L2 of the split member 424 obtained by removing a part
of the end portion adjacent to the coal secondary port 423 from the
split member 424 is set so that the dimensional ratio L2/L1
satisfies the in equation of L2/L1>0.2. Further, the dimension
ratio L2/L1 more desirably satisfies the in equation of
L2/L1>0.6. That is, it is desirable to form the removing portion
424a which is formed by removing a part of the end portion from the
split member 424 so that the dimension ratio satisfies the
condition of L2/L1>0.2. Then, it is more desirable to form the
removing portion to satisfy the condition of L2/L1>0.6.
[0377] The split member 424 employs, for example, the
cross-sectional shape illustrated in FIGS. 38A to 38D, and may
smoothly divide the flow of the pulverized coal and the air so as
to be disturbed.
[0378] The split member 424 illustrated in FIG. 38A has a
triangular cross-sectional shape. The triangular shape illustrated
in the drawings is an equilateral-triangular or isosceles triangle,
and the outlet side edge facing the inside of the furnace 411 is
disposed so as to be substantially perpendicular to the direction
in which the pulverized coal and the air flow. In other words, an
arrangement is employed in which one corner forming the triangular
cross-section faces the direction in which the pulverized coal and
the air flow.
[0379] A split member 424A illustrated in FIG. 38B has a
substantially T-shaped cross-section, and a surface substantially
perpendicular to the direction in which the pulverized coal and the
air flow is disposed at the outlet side facing the inside of the
furnace 411. Furthermore, for example, as illustrated in FIG. 38C,
a split member 424A' having a trapezoidal cross-sectional shape may
be formed by deforming the substantially T-shaped
cross-section.
[0380] A split member 424B illustrated in FIG. 38D has a
substantially L-shaped cross-section. That is, in a case where a
cross-section obtained by cutting out a part of the substantial
T-shape is particularly disposed in the left and right (horizontal)
direction, when a substantial L-shape is formed by removing an
upper convex portion, it is possible to prevent the deposit of the
pulverized coal to the split member 424B. Furthermore, when a lower
convex portion increases in size by the removable amount of the
upper convex portion, the separation performance necessary for the
split member 424B may be ensured.
[0381] However, the cross-sectional shape of the split member 424
or the like is not limited to the example illustrated in the
drawings, and may be substantially formed in, for example, a
Y-shape.
[0382] Incidentally, the split member 424 of the embodiment is not
limited thereto. Accordingly, the split member 424 may have, for
example, a configuration in which four split members are disposed
in total in a lattice shape so that two split members are disposed
in each of the up and down direction and the left and right
direction. In this case, the two split members disposed in the up
and down direction are provided so that both upper and lower end
portions near the secondary air input port 430 are removed. Then,
the two split members disposed in the left and right direction may
be provided so as to reach both left and right end portions of the
coal primary port 422. Likewise, various configurations may be
selected.
[0383] That is, when four split members 424 are provided, the split
members are disposed in a cross type so that the split members are
disposed in a lattice shape in two different directions of the up
and down direction and the left and right direction, so that the
outlet opening portion of the coal primary port 422 of the
pulverized coal burner 421 is finely divided (into nine segments).
Further, a pressure loss is large in a portion sandwiched by the
split members 424, and the flow velocity of the ejection port
decreases, so that the inner ignition is further promoted.
[0384] Furthermore, for example, regarding the up and down
direction of the split member 424, the removal portion (the
removing portion 424a) may not be positioned to the split member
424 in the left and right direction. Further, since the end portion
of the split member 424 may suppress the ignition at the outer
peripheral portion by the removal at the front side thereof, a
structure is desirable in which the outer periphery is not equipped
with the flame stabilizer.
[0385] Further, the removing portion 424a may be provided in a
direction in which the secondary air amount increases, that is, the
secondary air input port 430 is provided near the outer periphery
(the upper and lower sides) of the coal secondary port 423.
[0386] In the solid-fuel-combustion burner 420 with such a
configuration, the split member 424 that is provided near the
center of the outlet opening of the pulverized coal burner 421
divides the passage of the pulverized coal and the air so as to
disturb the flow therein, and forms the recirculation zone at the
front side (downstream side) of the split member 424. Thus, the
split member serves as an inner flame stabilization mechanism.
[0387] In general, the conventional solid-fuel-combustion burner
420 ignites the pulverized coal of the fuel by the radiation of the
outer periphery of the flame. When the pulverized coal is ignited
by the outer periphery of the flame, NOx is produced in the hot
oxygen remaining zone H (see FIG. 33B) of the outer periphery of
the flame where hot oxygen remains, and hence the NOx discharge
amount increase while the reduction is not sufficiently
performed.
[0388] However, since the split member 424 serving as the inner
flame stabilization mechanism is provided, the pulverized coal is
ignited at the inside of the flame. For this reason, NOx is
produced at the inside of the flame, and the NOx produced at the
inside of the flame contains a large amount of hydrocarbons having
a reduction action. For this reason, the reduction is promptly
performed inside the flame which does not have sufficient air.
Accordingly, the solid-fuel-combustion burner 420 is provided in a
structure in which the flame stabilization performed by the flame
stabilizer at the outer periphery of the flame is stopped, that is,
the flame stabilizing mechanism is not provided at the outer
periphery of the burner by forming the removing portion 424a, and
hence the production of NOx at the outer periphery of the flame may
be suppressed.
[0389] Particularly, when a cross type is employed in which the
split members 424 are disposed in a plurality of directions, the
intersection portion obtained by intersecting the split members 424
in different directions may be easily provided near the center of
the outlet opening of the pulverized coal burner 421. When the
intersection portion exists near the center of the outlet opening
of the pulverized coal burner 421, the passage of the pulverized
coal and the air is divided into plural segments near the center of
the outlet opening of the pulverized coal burner 421, and hence the
flow is disturbed when the flow is divided into plural flows.
[0390] That is, when the split members 424 exist in one direction
of the left and right direction, the dispersion or the ignition of
the air at the center portion is delayed, so that a zone exists in
which air is locally and extremely insufficient. Thus, the unburned
combustible content increases. However, in a cross type in which
the intersection portion is formed by disposing the split members
424 in a plurality of directions, the mixing of the air at the
inside of the flame is promoted and the ignition surface is finely
divided. As a result, the unburned combustible content may be
reduced.
[0391] In other words, when the split members 424 are disposed so
as to form the intersection portion, the mixing and the dispersion
of the air are promoted to the inside of the flame, so that the
ignition surface is finely divided. Thus, the ignition position
exists near the center portion (the axis center portion) of the
flame, and hence the unburned combustible content of the pulverized
coal is reduced. That is, since oxygen easily enters the center
portion of the flame, the inner ignition is effectively performed.
Accordingly, the reduction is promptly performed at the inside of
the flame, and hence the NOx production amount is reduced.
[0392] As a result, it is possible to more easily suppress the
production of NOx at the outer periphery of the flame by using the
solid-fuel-combustion burner 420 that does not have the flame
stabilizer at the outer periphery of the flame by stopping the
flame stabilization using the flame stabilizer provided at the
outer periphery of the flame.
[0393] In the split members 424 disposed in a plurality of
directions, in the embodiment, it is desirable to remove a
plurality of end portions adjacent to the coal secondary port 423
at the outer peripheral side of the split member 424, that is, at
least a part of left and right end portions.
[0394] In a first modified example of the configuration example
illustrated in FIG. 33A, as described above, both upper and lower
end portions as the outer peripheral side of the split member 424
in the up and down direction are removed. That is, in the outer
peripheral zone formed by removing both upper and lower end
portions of the split member 424, the split member 424 does not
exist, and the distance from the split member 424 to the coal
secondary port 423 and the secondary air input port 430 increases.
Furthermore, in the cross type split member 424, the outer
peripheral ignition occurs even at both left and right end portions
in the horizontal direction. However, in the turning combustion,
the amount of the secondary air blowing to the periphery of the
flame from the left and right direction is limited. For this
reason, in the embodiment, the ignition surface is ensured by
leaving both left and right end portions.
[0395] As a result, in the outer peripheral side zones of both
upper and lower end portions without the split member 424, the
ignition using the split member 424 as the ignition source does not
occur. Meanwhile, at the center portion side of the split member
424 as the inside of the flame, the flame stabilizing function may
be effectively used. Accordingly, in both upper and lower end
portion side zones that easily and directly interfere with the
secondary air due to the close distance with respect to the
secondary air input port 430 that inputs a large amount of the
secondary air, the ignition does not easily occurs. For this
reason, it is possible to prevent or suppress a zone with a high
temperature and a high oxygen concentration at the outer periphery
of the flame. That is, the split member 424 that is obtained by
removing both upper and lower end portions adjacent to the coal
secondary port 423 and the secondary air input port 430 may
strengthen the ignition inside the pulverized coal burner 420, and
prevent a hot oxygen zone at the outer periphery of the flame, that
is, the hot oxygen zones at the upper and lower ends of the
flame.
[0396] Incidentally, the removal of the end portion of the split
member 424 is not limited to the first modified example.
[0397] In a second modified example, two split members 424 are
disposed in each of the up and down direction and the left and
right direction. In this case, as in the above-described
embodiment, both upper and lower end portions near the coal
secondary port 423 and the secondary air input port 430 are removed
in the split member 424 in the up and down direction. The split
member 424 may be one or three or more.
[0398] In a third modified example, three split members 424 are
disposed in each of the up and down direction and the left and
right direction. In the split member 424 in the up and down
direction of the modified example, both upper and lower end
portions near the coal secondary port 423 and the secondary air
input port 430 of only one split member disposed at the center
portion is removed. Furthermore, in the split member 424 disposed
in the up and down direction, that is, the split member 424 in the
up and down direction of which both upper and lower end portions
are not removed, it is desirable to decrease the ignition surface
area by further narrowing the splitter widths W of both upper and
lower end portions or the entire portion.
[0399] In this way, in the solid-fuel-combustion burner 420 for the
turning combustion boiler in which the coal secondary port 423 and
the secondary air input port 430 are disposed near the upper and
lower sides of the pulverized coal burner 421, when the cross type
split member 424 of which at least a part of both upper and lower
end portions are removed is provided, it is possible to prevent or
suppress a zone with a high temperature and a high oxygen
concentration from being formed particularly at the upper and lower
end portions easily and directly interfering with the secondary
air.
[0400] When the hot oxygen remaining zone formed at the outer
periphery of the flame is suppressed in this way, the NOx produced
inside the flame generated by the pre-mixture combustion is
effectively reduced. Accordingly, it is possible to decrease the
NOx amount of NOx finally discharged from the AA part 414 due to a
decrease in the NOx amount reaching the AA part 414 or a decrease
in the NOx amount produced by the input of the additional air.
[0401] Further, in a fourth modified example, three or more cross
type split members 424 are disposed in at least one of the up and
down direction and the left and right direction, and the end
portions are removed except for at least one split member disposed
at the center portion in the up and down direction and the left and
right direction.
[0402] That is, in the fourth modified example, the configuration
in which three split members 424 are disposed in each of the up and
down direction and the left and right direction is the same as
those of the second modified example and the third modified
example. However, in the modified example, one split member 424
disposed at the center portion in the up and down direction and the
left and right direction is provided so as to reach the end
portion, and all end portions in the up and down direction and the
left and right direction of the split member 424 disposed at both
end portions are removed.
[0403] In this way, in a case of the split member 424 of the fourth
modified example, a structure is formed in which the split member
424 does not exist at the outer peripheral portion except for the
center portion in the up and down direction and the left and right
direction, and hence the split member 424 does not exist in a zone
which contributes the outer peripheral combustion the most. For
this reason, the split member 424 of the configuration example like
the fourth modified example effectively prevents the outer
peripheral ignition in which the split member 424 becomes the
ignition source.
[0404] Further, for example, like the fifth modified example, in
the split member 424 of the embodiment, at least a part of both
left and right end portions which may become the outer peripheral
ignition source may be removed if necessary.
[0405] That is, in the cross type split member 424 serving as the
flame stabilizer, the outer peripheral ignition may be generated
even at both left and right end portions in the horizontal
direction. Accordingly, the structure in which all end portions in
the up and down direction and the left and right direction are
removed may effectively and completely prevent the outer ignition.
Particularly, when the secondary air input port is provided at the
left and right sides of the pulverized coal burner 421, it is
desirable to remove both left and right end portions so as to
reduce the ignition source due to the same reason as that of the
above-described upper and lower secondary air input ports 430.
Sixteenth Embodiment
[0406] Next, a solid-fuel-combustion burner that is applied to a
opposed wall-fired boiler according to a sixteenth embodiment of
the invention will be described. In the solid-fuel-combustion
burner of the embodiment, a plurality of concentric secondary air
input ports are provided at the outer periphery of the coal primary
port having a circular cross-section. The secondary air input port
is formed as, for example, two stages with an inner secondary air
input port and an outer secondary air input port, but the invention
is not limited thereto.
[0407] Further, the center portion of the outlet of the coal
primary port is equipped with a plurality of split members (for
example, four split members disposed in the vertical direction and
the horizontal direction in total) that are disposed in a lattice
shape in two different directions. In this case, the split members
may be disposed by the number, the arrangement, and the
cross-sectional shape described in a fifteenth embodiment. However,
since the shape is particularly circular, it is desirable to remove
the end portion in the entire circumference. Alternatively, a
configuration may be employed in which a circular split member is
provided and plural radial split members are disposed inside the
circular shape so as to divide the circular circumferential
direction into plural segments. In this case, the circular split
members may have plural concentric circles.
[0408] According to the solid-fuel-combustion burner and the
solid-fuel-combustion boiler of the embodiment, it is possible to
reduce the final NOx production amount of NOx discharged from the
AA part 414 by suppressing the hot oxygen remaining zone H formed
at the outer periphery of the flame.
[0409] Furthermore, the invention is not limited to the
above-described embodiments. For example, the pulverized solid fuel
is not limited to the pulverized coal, and may be appropriately
modified without departing from the spirit of the invention.
Seventeenth Embodiment
[0410] In the pulverized-coal-combustion boiler, the pulverized
coal (coal) is used as the solid fuel. In this case, the coal
contains moisture or a volatile content, and the amount of moisture
changes in accordance with the type thereof. For this reason, there
is a need to control the operation of the boiler in response to the
volatile content or the moisture contained in the coal.
[0411] As the control of the operation of the boiler in
consideration of the volatile content of the coal, for example, the
control disclosed in Patent Literatures above is known. In the
pulverized coal burner and the boiler using the same disclosed in
Patent Literature 5, there are provided the pulverized coal
fuel-air mixture passage that ejects the pulverized coal fuel-air
mixture obtained by mixing the pulverized coal with the
transportation air and the hot gas supply passage that ejects a hot
gas with a low oxygen concentration at a high temperature effective
for the discharge of the volatile content of the pulverized coal.
Further, in the coal-combustion boiler disclosed in Patent
Literature 6, there are provided a temperature detector that
detects the temperature of the primary air for supplying the
pulverized coal to the coal-combustion boiler, the primary air
temperature adjusting unit that adjusts the temperature of the
primary air, and the control device that controls the primary air
temperature adjusting unit so that the temperature of the primary
air becomes a predetermined temperature based on the detection
result of the temperature detector.
[0412] In the conventional boiler, the entire pulverized coal is
heated so as to adjust the moisture or the volatile content, and is
burned inside the furnace. In this case, the operation parameter
needs to be adjusted based on the operation output of the boiler,
and it is difficult to directly set the operation parameter based
on the characteristics of the coal.
[0413] The invention is made to solve the above-described problems,
and it is an object of the invention to provide a boiler and a
method for operating the boiler capable of improving an operation
efficiency by appropriately burning solid fuel and a volatile
content contained in the solid fuel.
[0414] FIG. 39 is a schematic configuration diagram illustrating a
pulverized-coal-combustion boiler as a boiler according to a
seventeenth embodiment of the invention, FIG. 40 is a plan view
illustrating a combustion burner of the pulverized-coal-combustion
boiler of the seventeenth embodiment, FIG. 41 is a front view
illustrating the combustion burner of the seventeenth embodiment,
FIG. 42 is a cross-sectional view illustrating the combustion
burner of the seventeenth embodiment, and FIG. 43 is a graph
illustrating a NOx production amount and an unburned combustible
content production amount with respect to the primary air and the
secondary air.
[0415] The pulverized-coal-combustion boiler that employs the
combustion burner of the seventeenth embodiment is a boiler capable
of collecting the heat generated by the combustion by burning the
pulverized coal obtained by milling the coal as the solid fuel and
burning the pulverized coal through the combustion burner.
[0416] In the embodiment, as illustrated in FIG. 39, a
pulverized-coal-combustion boiler 510 is a conventional boiler, and
includes a furnace 511 and a combustion device 512. The furnace 511
is formed in a hollow square cylindrical shape, and is provided in
the vertical direction. Then, the combustion device 512 is provided
in the lower portion of the furnace wall forming the furnace
511.
[0417] The combustion device 512 includes plural combustion burners
521, 522, 523, 524, and 525 which are attached to the furnace wall.
In the embodiment, the combustion burners 521, 522, 523, 524, and
525 are disposed as one set in the circumferential direction at
four equal intervals therebetween, and five sets, that is, five
stages are disposed in the vertical direction.
[0418] Then, the respective combustion burners 521, 522, 523, 524,
and 525 are connected to coal pulverizers (mills) 531, 532, 533,
534, and 535 through pulverized coal supply pipes 526, 527, 528,
529, and 530. Although not illustrated in the drawings, the coal
pulverizers 531, 532, 533, 534, and 535 have a configuration in
which milling tables are supported in a rotational driving state
with rotation axes along the vertical direction inside a housing
and plural milling rollers are provided while facing the upper
sides of the milling tables and are supported so as to be rotatable
along with the rotation of the milling tables. Accordingly, when
coal is input between plural milling rollers and plural milling
tables, the coal is milled into a predetermined size therein. Thus,
pulverized coal which is classified by transportation air (primary
air) may be supplied from pulverized coal supply pipes 526, 527,
528, 529, and 530 to the combustion burners 521, 522, 523, 524, and
525.
[0419] Further, in the furnace 511, wind boxes 536 are provided at
the attachment positions of the respective combustion burners 521,
522, 523, 524, and 525, where one end portion of an air duct 537 is
connected to the wind box 536 and an air blower 538 is attached to
the other end portion of the air duct 537. Moreover, in the furnace
511, an additional air nozzle 539 is provided above the attachment
positions of the respective combustion burners 521, 522, 523, 524,
and 525, and an end portion of an air duct 540 branched from the
air duct 537 is connected to the additional air nozzle 539.
Accordingly, the combustion air (the secondary air and the tertiary
air) sent from the air blower 538 is supplied from the air duct 537
to the wind box 536 so as to be supplied from the wind boxes 36 to
the respective combustion burners 521, 522, 523, 524, and 525 and
to be supplied from the branched air duct 540 to the additional air
nozzle 539.
[0420] For this reason, in the combustion device 512, the
respective combustion burners 521, 522, 523, 524, and 525 may blow
a pulverized fuel-air mixture (fuel gas) obtained by mixing
pulverized coal and primary air into the furnace 511 and may blow
secondary air and tertiary air into the furnace 511. Then, a flame
may be formed by igniting the pulverized fuel-air mixture through
an ignition torch (not illustrated).
[0421] Further, the pulverized coal supply pipes 526, 527, 528,
529, and 530 are equipped with flowrate adjustment valves 541, 542,
543, 544, and 545 capable of adjusting the pulverized fuel-air
mixture amount, the air duct 537 is equipped with a flowrate
adjustment valve 546 capable of adjusting the amount of the
combustion air (the secondary air and the tertiary air), and the
branched air duct 540 is equipped with a flowrate adjustment valve
547 capable of adjusting the additional air amount. Then, a control
device 548 may adjust the opening degrees of the respective
flowrate adjustment valves 541, 542, 543, 544, 545, 546, and 547.
In this case, the pulverized coal supply pipes 526, 527, 528, 529,
and 530 may not be equipped with the flowrate adjustment valves
541, 542, 543, 544, and 545.
[0422] Furthermore, when generally activating the boiler, the
respective combustion burners 521, 522, 523, 524, and 525 form a
flame by ejecting oil fuel into the furnace 511.
[0423] A flue gas duct 550 is connected to the upper portion of the
furnace 511, and the flue gas duct 550 is equipped with
superheaters 551 and 552, reheaters 553 and 554, and economizers
555, 556, and 557 as convection heat transfer portions for
collecting the heat of the flue gas. Accordingly, a heat exchange
is performed between water and a flue gas that is produced by the
combustion in the furnace 511.
[0424] The downstream side of the flue gas duct 550 is connected
with a flue gas pipe 558 into which the flue gas subjected to the
heat exchange is discharged. An air heater 559 is provided between
the flue gas pipe 558 and the air duct 557, and a heat exchange is
performed between the air flowing through the air duct 537 and the
flue gas flowing through the flue gas pipe 558, so that the
temperature of the combustion air supplied to the combustion
burners 521, 522, 523, 524, and 525 may be increased.
[0425] Furthermore, although not illustrated in the drawings, the
flue gas pipe 558 is equipped with a denitration device, an
electronic precipitator, an inducing air blower, and a
desulfurization device, and the downstream end portion thereof is
equipped with a stack.
[0426] Accordingly, when the coal pulverizers 531, 532, 533, 534,
and 535 are driven, pulverized coal produced therein is supplied
along with the transportation air to the combustion burners 521,
522, 523, 524, and 525 through the pulverized coal supply pipes
526, 527, 528, 529, and 530. Further, the heated combustion air is
supplied from the air duct 537 to the respective combustion burners
521, 522, 523, 524, and 525 through the wind boxes 536, and is
supplied from the branched air duct 540 to the additional air
nozzle 539. Then, the combustion burners 521, 522, 523, 524, and
525 blow the pulverized fuel-air mixture obtained by mixing the
pulverized coal, the transportation air to the furnace 511 and blow
the combustion air to the furnace 511, and ignite the pulverized
fuel-air mixture and the air at this time so as to form a flame.
Further, the additional air nozzle 539 may perform the combustion
control by blowing the additional air to the furnace 511. In the
furnace 511, when a flame is generated by the combustion of the
pulverized fuel-air mixture and the combustion air and the flame is
generated at the lower portion inside the furnace 511, the
combustion gas (the flue gas) rises inside the furnace 511, and is
discharged to the flue gas duct 550.
[0427] Furthermore, the inside of the furnace 511 is maintained at
the reduction atmosphere in a manner such that the air supply
amount with respect to the pulverized coal supply amount becomes
smaller than the theoretical air amount. Then, when NOx produced by
the combustion of the pulverized coal is reduced in the furnace 511
and additional air is additionally supplied thereto, the
oxidization combustion of the pulverized coal is completed and
hence the production amount of NOx caused by the combustion of the
pulverized coal is reduced.
[0428] At this time, water supplied from a water feeding pump (not
illustrated) is preheated by the economizers 555, 556, and 557, is
supplied to a steam drum (not illustrated), and heated while being
supplied to the respective water pipes (not illustrated) of the
furnace wall so as to become saturated steam. Then the saturated
steam is transported to a steam drum (not illustrated). Further,
the saturated steam of the steam drum (not illustrated) is
introduced into the superheaters 551 and 552 and is superheated by
the combustion gas. The superheated steam produced by the
superheaters 551 and 552 is supplied to a power generation plant
(not illustrated) (for example, a turbine or the like). Further,
the steam which is extracted during the expanding process in the
turbine is introduced into the reheaters 553 and 554, is
superheated again, and is returned to the turbine. Furthermore, the
furnace 511 of a drum type (steam drum) has been described, but the
invention is not limited to the structure.
[0429] Subsequently, a harmful substance such as NOx is removed
from the flue gas which passes through the economizers 555, 556,
and 557 of the flue gas duct 550 by a catalyst of a denitration
device (not illustrated) in the flue gas pipe 558, a particulate
substance is removed therefrom by the electronic precipitator, and
a sulfur content is removed therefrom by the desulfurization
device. Then, the flue gas is discharged to the atmosphere through
the stack.
[0430] Here, the combustion device 512 will be described in detail,
but since the respective combustion burners 521, 522, 523, 524, and
525 constituting the combustion device 512 have substantially the
same configuration, only the combustion burner 521 that is
positioned at the uppermost stage will be described.
[0431] As illustrated in FIG. 40, the combustion burner 521
includes the combustion burners 521a, 521b, 521c, and 521d which
are provided at four wall surfaces of the furnace 511. The
respective combustion burners 521a, 521b, 521c, and 521d are
connected with respective branch pipes 526a, 526b, 526c, and 526d
which are branched from a pulverized coal supply pipe 526, and are
connected with respective branch pipes 537a, 537b, 537c, and 537d
branched from the air duct 537.
[0432] Accordingly, the respective combustion burners 521a, 521b,
521c, and 521d which are positioned at the respective wall surfaces
of the furnace 511 blow the pulverized fuel-air mixture obtained by
mixing the pulverized coal and the transportation air to the
furnace 511 and blow the combustion air to the outside of the
pulverized fuel-air mixture. Then, the pulverized fuel-air mixture
is ignited from the respective combustion burners 521a, 521b, 521c,
and 521d, so that four flames F1, F2, F3, and F4 may be formed. The
flames F1, F2, F3, and F4 become a flame swirl flow that turns in
the counter-clockwise direction when viewed from the upside of the
furnace 511 (in FIG. 40).
[0433] As illustrated in FIGS. 41 and 42, in the combustion burner
521 (521a, 521b, 521c, 521d) with such a configuration, the
combustion burner is equipped a fuel nozzle 561, a secondary air
nozzle 562, and a tertiary air nozzle 563 from the center side
thereof and is equipped with a flame stabilizer 564. The fuel
nozzle 561 may blow the fuel gas (the pulverized fuel-air mixture)
obtained by mixing the pulverized coal (the solid fuel) with the
transportation air (the primary air). The secondary air nozzle 562
is disposed at the outside of the first nozzle 561 and may blow the
combustion air (the secondary air) to the outer peripheral side of
the fuel gas ejected from the fuel nozzle 561. The tertiary air
nozzle 563 is disposed at the outside of the secondary air nozzle
562, and may blow the tertiary air to the outer peripheral side of
the secondary air ejected from the secondary air nozzle 562.
[0434] Further, the flame stabilizer 564 is disposed inside the
fuel nozzle 561 so as to be positioned at the downstream side of
the fuel gas blowing direction and near the axis center, and serves
to ignite and stabilize the fuel gas. The flame stabilizer 564 is
formed in a so-called double cross split structure in which two
flame stabilizing members following the horizontal direction and
two flame stabilizing members following the vertical direction (the
up and down direction) are disposed in a cross shape. Then, in the
flame stabilizer 564, the widened portions are formed in the front
end portions of the respective flame stabilizing members (the
downstream end portions in the fuel gas flowing direction).
[0435] For this reason, each of the fuel nozzle 561 and the
secondary air nozzle 562 has an elongated tubular shape, the fuel
nozzle 561 includes a rectangular opening portion 561a, and the
secondary air nozzle 562 includes a rectangular annular opening
portion 562a. Thus, the fuel nozzle 561 and the secondary air
nozzle 562 are formed in a double tube structure. the tertiary air
nozzle 563 is disposed as a double tube structure at the outside of
the fuel nozzle 561 and the secondary air nozzle 562, and includes
a rectangular annular opening portion 563a. As a result, the
opening portion 562a of the secondary air nozzle 562 is disposed at
the outside of the opening portion 561a of the fuel nozzle 561, and
the opening portion 563a of the tertiary air nozzle 563 is disposed
at the outside of the opening portion 562a of the secondary air
nozzle 562.
[0436] In the nozzles 561, 562, and 563, the opening portions 561a,
562a, and 563a are disposed so as to be flush with one another.
Further, the flame stabilizer 564 is supported by the inner wall
surface of the fuel nozzle 561 or a plate member (not illustrated)
from the upstream side of the passage through which the fuel gas
flows. Further, since plural flame stabilizing members are disposed
as the flame stabilizer 564 inside the fuel nozzle 561, the fuel
gas passage is divided into nine segments. Then, in the flame
stabilizer 564, the widened portion of which the width is wide is
positioned at the front end portion thereof, and the front end
surface of the widened portion is disposed so as to be flush with
the opening portion 561a.
[0437] Further, in the combustion burner 521, the fuel nozzle 561
is connected to the pulverized coal supply pipe 526 from the coal
pulverizer 531. The secondary air nozzle 562 is connected with one
connection duct 566 branched from the air duct 537 from the air
blower 538, and the tertiary air nozzle 563 is connected with the
other connection duct 567 branched from the air duct 537. A
flowrate adjustment valve (a three-way valve or a damper) 568 is
attached to the branch portions of the respective connection ducts
566 and 567 from the air duct 537. Then, the control device 548
(see FIG. 39) may adjust the opening degree of the flowrate
adjustment valve 568, and may adjust the distribution of the air to
the respective connection ducts 566 and 567.
[0438] Accordingly, in the combustion burner 521, the fuel gas
obtained by mixing the pulverized coal with the primary air blows
from the opening portion 561a of the fuel nozzle 561 into the
furnace, the secondary air blows from the opening portion 562a of
the secondary air nozzle 562 to the outside thereof, and the
tertiary air blows from the opening portion 563a of the tertiary
air nozzle 563 to the outside thereof. At this time, the fuel gas
is branched at the opening portion 561a of the fuel nozzle 561 by
the flame stabilizer 564, and is ignited and burned so as to become
a fuel gas. Further, since the secondary air blows to the outer
periphery of the fuel gas, the combustion of the fuel gas is
promoted. Further, since the tertiary air blows to the outer
periphery of the combustion flame, the outer peripheral portion of
the combustion flame is cooled.
[0439] Then, since the flame stabilizer 564 is formed in a split
shape in the combustion burner 521, the fuel gas is divided by the
flame stabilizer 564 at the opening portion 561a of the fuel nozzle
561. At this time, the flame stabilizer 564 is disposed at the
center zone of the opening portion 561a of the fuel nozzle 561, and
the fuel gas is ignited and stabilized at the center zone. Thus,
the inner flame stabilization of the combustion flame (the flame
stabilization at the center zone of the opening portion 561a of the
fuel nozzle 561) is realized.
[0440] For this reason, compared to the configuration in which the
outer flame stabilization of the combustion flame is performed, the
temperature of the outer peripheral portion of the combustion flame
becomes low, and hence the temperature of the outer peripheral
portion of the combustion flame under the high oxygen atmosphere by
the secondary air may become low. Thus, the NOx production amount
at the outer peripheral portion of the combustion flame is
reduced.
[0441] Further, since the combustion burner 521 employs a
configuration in which the inner flame stabilization is performed,
it is desirable to supply the fuel gas and the combustion air (the
secondary air and the tertiary air) as a straight flow. That is, it
is desirable that the fuel nozzle 561 have a structure in which the
secondary air nozzle 562 and the tertiary air nozzle 563 supply the
fuel gas, the secondary air, and the tertiary air as a straight
flow instead of a swirl flow. Since the fuel gas, the secondary
air, and the tertiary air are ejected as the straight flow so as to
form the combustion flame, the circulation of the gas inside the
combustion flame is suppressed in the configuration in which the
inner flame stabilization of the combustion flame is performed.
Accordingly, the outer peripheral portion of the combustion flame
is maintained in a low temperature, and the NOx production amount
caused by the mixture with the secondary air is reduced.
[0442] Incidentally, in the pulverized-coal-combustion boiler 510
of the embodiment, the pulverized coal (coal) is used as the solid
fuel, and the pulverized coal contains the volatile content.
Accordingly, the combustion state becomes different due to the
volatile content.
[0443] Therefore, in the pulverized-coal-combustion boiler 510 of
the embodiment, as illustrated in FIGS. 39 and 42, since the
control device 548 may adjust the fuel gas amount, the secondary
air amount, the tertiary air amount, and the additional air amount
by changing the opening degrees of the respective flowrate
adjustment valves 541, 542, 543, 544, 545, 546, 547, and 568, the
fuel gas amount, the secondary air amount, the tertiary air amount,
and the additional air amount are adjusted in response to the
volatile content of the pulverized coal.
[0444] In this case, it is desirable that the control device 548
adjust the distribution of the total air amount of the primary air
and the secondary air and the air amount of the additional air in
response to the volatile content of the pulverized coal.
Specifically, the distribution of the total air amount of the
primary air and the secondary air and the total air amount of the
tertiary air and the additional air is adjusted.
[0445] In the embodiment, since the primary air amount and the
additional air amount are predetermined air amounts, the control
device 548 adjusts the distribution of the secondary air and the
tertiary air in response to the volatile content of the pulverized
coal. Then, the control device 548 increases the distribution of
the secondary air when the volatile content of the pulverized coal
increases.
[0446] That is, since the fuel nozzle 561 blows the fuel gas
obtained by mixing the pulverized coal with the primary air into
the furnace 511 and the primary air is the transportation air for
the pulverized coal, the distribution of the primary air and the
pulverized coal of the fuel gas, that is, the primary air amount is
determined by the coal pulverizers 531, 532, 533, 534, and 535.
Further, the additional air nozzle 539 performs oxidization
combustion by inputting the combustion air to the combustion
performed by the combustion burners 521, 522, 523, 524, and 525 to
thereby completely perform the combustion. Here, since the
additional air from the additional air nozzle 539 strengthens the
reduction atmosphere in the main combustion zone and reduces the
NOx discharge amount, the additional air amount for each boiler is
determined.
[0447] Meanwhile, the secondary air nozzle 562 is used to blow the
air as the secondary air passing from the air duct 537 to the
connection duct 566 into the furnace 11, and the air is mainly used
as the combustion air which is burned while being mixed with the
fuel gas blowing from the fuel nozzle 561. The tertiary air nozzle
563 is used to blow the air as the tertiary air passing from the
air duct 537 to the connection duct 566 into the furnace 511, and
the air is mainly used as the additional air with respect to the
combustion flame as in the additional air nozzle 359.
[0448] For this reason, the control device 548 changes the opening
degree of the flowrate adjustment valve 568 so as to adjust the
distribution of the total air amount of the primary air and the
secondary air and the total air amount of the tertiary air and the
additional air, that is, the distribution of the air amounts of the
secondary air and the tertiary air, and hence handle a change in
the volatile content of the pulverized coal. Here, when the
volatile content of the pulverized coal increases, the control
device 548 decreases the tertiary air amount and increases the
secondary air amount so as to change the distribution of the
secondary air and the tertiary air.
[0449] Here, as illustrated in FIG. 43, when the total air amount
of the primary air and the secondary air increases, the NOx
production amount increases and the unburned combustible content
production amount decreases. That is, in the combustion burners
521, 522, 523, 524, and 525, the volatile content of the pulverized
coal is mainly burned at the ignition portion (the vicinity of the
opening portion 551a of the fuel nozzle 551). Then, when the air
amount therein excessively increases, the NOx production amount
increases. On the other hand, when the air amount therein is not
sufficient, the pulverized coal is not smoothly burned, and the
unburned combustible content production amount increases. For this
reason, in the combustion burners 521, 522, 523, 524, and 525,
there is a need to set the air amount as the amount in which the
NOx production amount and the unburned combustible content
production amount are suppressed to be low in consideration of the
volatile content of the pulverized coal at the ignition
portion.
[0450] Furthermore, the volatile content of the pulverized coal is
measured before the coal is input to the respective coal
pulverizers 531, 532, 533, 534, and 535, and the volatile content
is stored as data in the control device 548. Further, since the
distribution ratio of the secondary air and the tertiary air with
respect to the volatile content of the pulverized coal becomes
different depending on the type of the boiler or the combustion
types of the combustion burners 521, 522, 523, 524, and 525, the
distribution ratio is set in advance by an experiment. For example,
a map is prepared, and is stored in the control device 548.
[0451] Accordingly, in the combustion burners 521, 522, 523, 524,
and 525, the fuel gas blows from the fuel nozzle 561 to the furnace
511, the secondary air blows from the secondary air nozzle 562 to
the furnace, and the tertiary air blows from the tertiary air
nozzle 563 to the furnace. At this time, the fuel gas is ignited
and burned by the flame stabilizer 564, and is further burned while
being mixed with the secondary air. At this time, the main
combustion zone is formed inside the furnace 511. Then, since the
tertiary air blows from the tertiary air nozzle 563 to the main
combustion zone, the outer peripheral portion of the combustion
flame is cooled and the combustion thereof is promoted.
Subsequently, the additional air nozzle 539 blows the additional
air to the furnace 511 so as to perform the combustion control.
[0452] That is, in the furnace 511, the combustion gas which is
obtained by the combustion of the fuel gas from the fuel nozzles
561 of the combustion burners 521, 522, 523, 524, and 525 and the
secondary air from the secondary air nozzle 562 becomes less than a
theoretical air amount, and the inside of the furnace is maintained
at the reduction atmosphere. Then, the NOx which is produced by the
combustion of the pulverized coal is reduced by the tertiary air.
Subsequently, the oxidization combustion of the pulverized coal is
completed by the additional air, and the NOx production amount
caused by the combustion of the pulverized coal is reduced.
[0453] At this time, the control device 548 obtains the
distribution ratio of the secondary air and the tertiary air in the
combustion burners 521, 522, 523, 524, and 525 based on the
volatile content of the pulverized coal measured in advance and the
previously stored distribution ratio map of the secondary air and
the tertiary air with respect to the volatile content of the
pulverized coal, and sets the opening degree of the flowrate
adjustment valve 568. Then, the control device 548 adjusts the
opening degree of the flowrate adjustment valve 568 based on the
set opening degree. Then, in the combustion burners 521, 522, 523,
524, and 525, the secondary air amount from the secondary air
nozzle 562 and the tertiary air amount from the tertiary air nozzle
563 become optimal for the volatile content of the pulverized coal,
and hence the pulverized coal and the volatile content are
appropriately burned.
[0454] In this way, the boiler of the seventeenth embodiment
includes the furnace 511 which burns the pulverized coal and the
air, the superheaters 551 and 552 which collect heat by the heat
exchange inside the furnace 511, the fuel nozzle 561 which is able
to blow the fuel gas obtained by mixing the pulverized coal with
the primary air to the furnace 511, the secondary air nozzle 562
which is able to blow the secondary air to the furnace 511, the
tertiary air nozzle 563 which is able to blow the tertiary air to
the furnace 511, the additional air nozzle 539 which is able to
blow the additional air to the upper side of the fuel nozzle 561
and the secondary air nozzle 562 in the furnace 511, the flowrate
adjustment valve 568 which performs the distribution of the
secondary air amount and the tertiary air amount, and the control
device 548 which controls the opening degree of the flowrate
adjustment valve 568 in response to the volatile content of the
pulverized coal.
[0455] Accordingly, since the control device 548 adjusts the
distribution of the air amount of the secondary air nozzle 562 and
the air amount of the tertiary air nozzle 563 by controlling the
opening degree of the flowrate adjustment valve 568 in response to
the volatile content of the pulverized coal, the secondary air
amount and the tertiary air amount are adjusted in response to the
volatile content of the pulverized coal. Accordingly, the volatile
content of the pulverized coal may be appropriately burned, and the
pulverized coal may be appropriately burned. Thus, the production
of the NOx or the unburned combustible content may be suppressed,
and hence the boiler operation efficiency may be improved. Further,
the pulverized coal and the volatile content thereof may be
appropriately burned while maintaining a predetermined fuel-air
ratio.
[0456] Further, in the boiler of the seventeenth embodiment, the
control device 548 increases the distribution of the secondary air
when the volatile content of the pulverized coal increases. Since
the secondary air is the combustion air which burns the pulverized
coal while being mixed with the fuel gas, the distribution of the
secondary air increases when the volatile content of the pulverized
coal increases, so that the pulverized coal and the volatile
content thereof may be appropriately burned.
[0457] Further, in the method for operating the boiler of the
seventeenth embodiment, the distribution of the secondary air and
the tertiary air is adjusted in response to the volatile content of
the pulverized coal in the pulverized-coal-combustion boiler 510.
Accordingly, the volatile content of the pulverized coal may be
appropriately burned, and the pulverized coal may be appropriately
burned. Thus, the production of the NOx or the unburned combustible
content may be suppressed, and hence the boiler operation
efficiency may be improved.
[0458] Furthermore, in the above-described embodiment, the
distribution of the secondary air amount and the tertiary air
amount is adjusted and the distribution of the secondary air
increases when the volatile content of the pulverized coal
increases. However, the invention is not limited to the
configuration. For example, in the coal pulverizers 531, 532, 533,
534, and 535, the air amount (the transportation air amount) may be
increased or decreased or the additional air amount may be
increased or decreased.
[0459] Further, the boiler of the invention is not limited to the
configuration of the pulverized-coal-combustion boiler 510 or the
configuration or the number of the combustion burners 521, 522,
523, 524, and 525.
[0460] Further, in the above-described embodiment, as the
combustion device 512, four combustion burners 521, 522, 523, 524,
and 525 respectively provided in the wall surface of the furnace
511 are disposed as a five stages in the vertical direction, but
the configuration is not limited thereto. That is, the combustion
burner may be disposed at the corner instead of the wall surface.
Further, the combustion device is not limited to the turning
combustion type, and may be a front combustion type in which the
combustion burner is disposed in one wall surface or an opposed
combustion type in which the combustion burners are disposed in two
wall surfaces so as to be opposed to each other.
REFERENCE SIGNS LIST
[0461] 10 PULVERIZED-COAL-COMBUSTION BOILER [0462] 11 FURNACE
[0463] 21, 22, 23, 24, 25 COMBUSTION BURNER [0464] 51, 111 FUEL
NOZZLE [0465] 52, 112 SECONDARY AIR NOZZLE [0466] 53, 113 TERTIARY
AIR NOZZLE [0467] 54, 71, 81, 91, 114, 121, 131, 161 FLAME
STABILIZER [0468] 55, 75, 95, 101, 115, 135, 141, 151 RECTIFICATION
MEMBER [0469] 210 PULVERIZED-COAL-COMBUSTION BOILER [0470] 211
FURNACE [0471] 221, 222, 223, 224, 225 COMBUSTION BURNER [0472] 251
FUEL NOZZLE [0473] 252 SECONDARY AIR NOZZLE [0474] 253 TERTIARY AIR
NOZZLE [0475] 254, 291 FLAME STABILIZER [0476] 255, 271 GUIDE
MEMBER [0477] 261, 262, 263, 264 FLAME STABILIZING MEMBER [0478]
261c, 262c, 263c, 264c NOTCHED SURFACE (GUIDE MEMBER) [0479] 281,
282, 283, 284 TRIANGULAR PLATE (GUIDE MEMBER) [0480] 297 DRIVING
DEVICE [0481] 310 TURNING COMBUSTION BOILER [0482] 311 FURNACE
[0483] 312 BURNER [0484] 314 ADDITIONAL AIR INPUT UNIT (AA PART)
[0485] 320, 320A SOLID-FUEL-COMBUSTION BURNER [0486] 321 PULVERIZED
COAL BURNER (FUEL BURNER) [0487] 322 COAL PRIMARY PORT [0488] 323
COAL SECONDARY PORT [0489] 324 SPLIT MEMBER [0490] 324V VERTICAL
SPLITTER [0491] 324H HORIZONTAL SPLITTER [0492] 330 SECONDARY AIR
INPUT PORT [0493] 340 DAMPER [0494] 350 TRIANGULAR PLATE (SHIELDING
MEMBER) [0495] 350A TRIANGULAR PYRAMID (SHIELDING MEMBER) [0496]
410 TURNING COMBUSTION BOILER [0497] 411 FURNACE [0498] 412 BURNER
[0499] 414 ADDITIONAL AIR INPUT UNIT (AA PART) [0500] 420
SOLID-FUEL-COMBUSTION BURNER [0501] 421 PULVERIZED COAL BURNER
(FUEL BURNER) [0502] 422 COAL PRIMARY PORT [0503] 423 COAL
SECONDARY PORT [0504] 424 SPLIT MEMBER [0505] 424a REMOVING PORTION
[0506] 430 SECONDARY AIR INPUT PORT [0507] 440 DAMPER [0508] 510
PULVERIZED-COAL-COMBUSTION BOILER [0509] 511 FURNACE [0510] 521,
522, 523, 524, 525 COMBUSTION BURNER [0511] 537 AIR DUCT [0512] 539
ADDITIONAL AIR NOZZLE (ADDITIONAL AIR NOZZLE) [0513] 540 BRANCHED
AIR DUCT [0514] 541, 542, 543, 544, 545, 546, 547, 568 FLOWRATE
ADJUSTMENT VALVE (AIR AMOUNT ADJUSTING DEVICE) [0515] 548 CONTROL
DEVICE [0516] 551, 552 SUPERHEATER (HEAT EXCHANGER) [0517] 553, 554
REHEATER (HEAT EXCHANGER) [0518] 555, 556, 557 ECONOMIZER (HEAT
EXCHANGER) [0519] 561 FUEL NOZZLE [0520] 562 SECONDARY AIR NOZZLE
[0521] 563 TERTIARY AIR NOZZLE
* * * * *