U.S. patent application number 12/442745 was filed with the patent office on 2010-03-18 for burner, and combustion equipment and boiler comprising burner.
This patent application is currently assigned to BABCOCK-HITACHI KABUSHIKI KAISHA. Invention is credited to Akira Baba, Kenji Kiyama, Kouji Kuramashi, Osamu Okada, Hirofumi Okazaki, Takanori Yano.
Application Number | 20100064986 12/442745 |
Document ID | / |
Family ID | 39229869 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100064986 |
Kind Code |
A1 |
Kiyama; Kenji ; et
al. |
March 18, 2010 |
BURNER, AND COMBUSTION EQUIPMENT AND BOILER COMPRISING BURNER
Abstract
The present invention provides a solid fuel burner, which, while
rendering the capacity larger than that in the conventional art,
can suppress an increase in an unignited region and thus can
realize the prevention of an increase in NOx concentration in a
combustion gas and the prevention of a lowering in combustion
efficiency, and a combustion equipment and boiler including the
burner. The burner includes a fuel-containing fluid supply nozzle
(12) which supplies a fuel-containing fluid, from a connecting part
in a fluid transfer flow passage (10) for transferring a
fuel-containing fluid including a fuel and a medium for transfer of
the fuel, toward an outlet part provided on the wall of a furnace
(4). The fuel-containing fluid supply nozzle (12) in its cross
section perpendicular to the direction of flow of the fluid is in a
rectangular, elliptical, or substantially elliptical form having
major and minor axis parts from a connecting part (10a) in the
fluid transfer flow passage (10) toward the outlet part provided on
the wall surface of the furnace (4). Further, the area of a cross
section perpendicular to the direction of flow of the fluid is
gradually increased from the connecting part in the fluid transfer
flow passage (10) toward the outlet part. One or more air supply
nozzles (15) for supplying combustion air are provided on the outer
peripheral part of the nozzle (12).
Inventors: |
Kiyama; Kenji; (Hiroshima,
JP) ; Baba; Akira; (Hiroshima, JP) ; Yano;
Takanori; (Hiroshima, JP) ; Okada; Osamu;
(Hiroshima, JP) ; Okazaki; Hirofumi; (Hiroshima,
JP) ; Kuramashi; Kouji; (Hiroshima, JP) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
BABCOCK-HITACHI KABUSHIKI
KAISHA
Tokyo
JP
|
Family ID: |
39229869 |
Appl. No.: |
12/442745 |
Filed: |
March 27, 2007 |
PCT Filed: |
March 27, 2007 |
PCT NO: |
PCT/JP2007/056311 |
371 Date: |
March 25, 2009 |
Current U.S.
Class: |
122/16.1 ;
110/261; 431/190 |
Current CPC
Class: |
F23D 1/005 20130101;
F22B 1/1869 20130101; F23D 1/00 20130101; F23D 2201/20 20130101;
F23D 2201/10 20130101; F22B 21/26 20130101 |
Class at
Publication: |
122/16.1 ;
431/190; 110/261 |
International
Class: |
F24H 1/00 20060101
F24H001/00; F23L 9/00 20060101 F23L009/00; F23C 1/10 20060101
F23C001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2006 |
JP |
2006-263336 |
Claims
1. A burner including: a fuel-containing fluid supply nozzle
supplying a fuel-containing fluid, containing a solid fuel and a
medium for transfer of the solid fuel, to an outlet part disposed
on a wall surface of a furnace from a connecting part of a
fuel-containing fluid transfer flow passage that transfers the
fluid; and one or more air supply nozzles supplying combustion air
and disposed at an outer peripheral part of the fuel-containing
fluid supply nozzle; wherein, from the connecting part of the fluid
transfer flow passage toward the outlet part disposed on the wall
surface of the furnace, a cross section of the fuel-containing
fluid supply nozzle perpendicular to a flow of the fluid has a
rectangular, elliptical, or substantially elliptical shape with
major and minor axis parts and, from the connecting part of the
fluid transfer flow passage toward the outlet part, a size of the
major axis part of the cross section perpendicular to the flow of
the fluid increases gradually along a direction of the flow of the
fluid and a size of the minor axis part is unchanged.
2. (canceled)
3. (canceled)
4. The burner according to claim 1, wherein the fuel-containing
fluid supply nozzle has, in an interior thereof, fuel-containing
fluid guide plates plurally partitioning the flow of the
fuel-containing fluid.
5. The burner according to claim 4, wherein the fuel-containing
fluid guide plates are disposed at a plurality of different
inclination angles with respect to planes parallel to a plane
passing along a line extending a central axis in the direction of
the flow of the fluid in the fuel-containing fluid supply nozzle
toward the furnace and passing through a shortest axis of the minor
axis part of the nozzle.
6. The burner according to claim 1, wherein the fuel-containing
fluid supply nozzle has, in an interior of the outlet thereof,
fuel-containing fluid direction changing guide plates forcibly
changing a direction of ejection flow of the fuel-containing
fluid.
7. The burner according to claim 6, wherein the fuel-containing
fluid direction changing guide plates are disposed in a plurality
of mutually different directions with respect to planes parallel to
a plane passing along a line extending the central axis of the
fuel-containing fluid supply nozzle toward the furnace and passing
through a longest axis of the major axis part of the nozzle.
8. The burner according to claim 6, wherein the fuel-containing
fluid direction changing guide plates for a portion of the
fuel-containing fluid are disposed parallel to planes parallel to a
plane passing along a line extending the central axis of the
fuel-containing fluid supply nozzle toward the furnace and passing
through a longest axis of the major axis part of the nozzle, and
the fuel-containing fluid direction changing guide plates for
another portion of the fuel containing fluid are disposed at an
inclination angle with respect to the plane passing along the line
extending the central axis of the fuel-containing fluid supply
nozzle toward the furnace and parallel to the longest axis of the
major axis part of the nozzle.
9. The burner according to claim 4, wherein the fuel-containing
fluid supply nozzle is partitioned into a plurality of flow
passages by the fuel-containing fluid guide plates, and central
axes of the respective flow passages are disposed at the wall
surface of the furnace at a plurality of mutually different
inclination angles with respect to planes parallel to a plane
passing along a line extending the central axis of the
fuel-containing fluid supply nozzle toward the furnace and passing
through a longest axis of the major axis part of the nozzle
outlet.
10. The burner according to claim 1, wherein fuel-containing fluid
partitioning plates, capable of plurally partitioning the outlet
part of the fuel-containing fluid supply nozzle, are disposed at
the outlet part.
11. The burner according to claim 1, wherein a flame stabilizer
with an L-shaped cross section is disposed at the outlet part of
the fuel-containing fluid supply nozzle.
12. The burner according to claim 11, wherein a guide plate
outwardly changing an ejection direction of the combustion air in a
periphery of the flame stabilizer is disposed at a front end of the
L-shaped flame stabilizer.
13. The burner according to claim 1, wherein a combustion air guide
plate, outwardly spreading an ejection direction of the combustion
air at an outer side of the one or more combustion air supply
nozzles disposed at the outer peripheral part of the nozzle with
respect to a fuel ejection direction, is disposed at a front end of
the combustion air supply nozzles.
14. The burner according to claim 1, wherein a condenser, narrowing
the flow passage of the fuel-containing fluid once and then
expanding the flow passage again, is disposed in an interior of the
fuel-containing fluid supply nozzle.
15. The burner according to claim 1, wherein a fluid distribution
plate, distributing the fuel uniformly inside the fuel-containing
fluid supply nozzle is disposed at an inlet part of the
fuel-containing fluid supply nozzle.
16. The burner according to claim 1, wherein a nozzle, ejecting a
liquid fuel or a gas fuel that is an auxiliary fuel to a vicinity
of the fluid ejected from the fuel-containing fluid supply nozzle,
is disposed at a vicinity of the fuel-containing fluid supply
nozzle.
17. A combustion equipment wherein the burners according to claim 1
are disposed in a plurality of stages in an up/down direction at
each of two opposing furnace walls, and a plurality of burners
disposed at each stage are disposed respectively symmetrically in
wall surface regions divided in two at a central part of width in a
horizontal direction of the same furnace wall.
18. A combustion equipment wherein the burners according to claim 1
are disposed in a plurality of stages in an up/down direction at
each of two opposing furnace walls, and burners, which, among the
plurality of burners disposed in each stage of the same furnace
wall, are adjacent each other in a horizontal direction, are
burners of the same structure.
19. A boiler including: a furnace wall formed by spirally winding a
set of water wall tubes inclined with respect to a horizontal
direction; wherein openings of rectangular, elliptical, or
substantially elliptical shape are disposed in the furnace wall
along a longitudinal direction of the water wall tubes and the
burner according to claim 1 is mounted in each opening.
20. A boiler including: a furnace wall formed by a set of water
wall tubes extending in a vertical direction; wherein openings of
rectangular, elliptical, or substantially elliptical shape are
disposed in the furnace wall along a longitudinal direction of the
water wall tubes and the burner according to claim 1 is mounted in
each opening.
Description
FIELD OF THE ART
[0001] The present invention relates to a burner and a combustion
equipment and a boiler including the burner, and particularly
relates to a burner capable of performing low nitrogen oxide (NOx)
combustion at high efficiency.
BACKGROUND ART
[0002] FIG. 28 shows an example of a solid fuel (pulverized coal,
biomass fuel, etc.) burner according to a conventional art. FIG.
28A is a side sectional view of the burner, and FIG. 28B is a front
view of the burner as viewed from a furnace (4) side. The solid
fuel burner includes a fuel-containing fluid supply nozzle (12),
defining a fuel-containing fluid flow passage through which a
fuel-containing fluid (11), containing a solid fuel and a conveying
primary air, flows toward the furnace (4), and a combustion air
sleeve (15) disposed at an outer periphery of the fuel-containing
fluid supply nozzle (12), and air inside a windbox (3) is supplied
as a secondary air (13) and a tertiary air (14) through a
combustion air flow passage defined by the sleeve (15). A flame
stabilizer (17) is disposed at a front end of the fuel-containing
fluid supply nozzle (12), and ignition of the fuel from a vicinity
of the burner is enabled by an effect of a circular vortex formed
at a wake of the flame stabilizer (17).
[0003] A front end of the combustion air sleeve (15) is disposed at
a position facing a burner throat (16), a combustion air guide
plate (15a), spreading outside the burner, is disposed at the front
end of the sleeve (15), the tertiary air (14) is spread outward by
the combustion air guide plate (15a) to delay mixing of air into a
central part of a flame, and by promotion of combustion under a
reducing atmosphere condition of insufficient air, generation of
nitrogen oxides (NOx) in a combustion gas is suppressed.
[0004] FIG. 1C is a sectional view taken in a direction along an
ejection flow of the fuel-containing fluid (11) at the
fuel-containing fluid supply nozzle (12) in the burner of the
conventional art, and as shown in FIG. 1D, which is a front view of
an outlet part of the fuel-containing fluid supply nozzle (12) of
the burner in FIG. 1C as viewed from the furnace (4) side, with the
burner of the conventional art, a cross section of the outlet part
of the fuel-containing fluid supply nozzle (12) has a shape close
to a circular shape. When the fuel-containing fluid (11) is loaded
into the furnace (4), the fuel is ignited near the outlet of the
fuel-containing fluid supply nozzle (12) by heating due to
radiation inside the furnace (4) and actions of the circular vortex
at the wake of the flame stabilizer (17).
[0005] FIG. 29A is a sectional view taken in a direction along the
ejection flow of the fuel-containing fluid (11) at the
fuel-containing fluid supply nozzle (12) in the burner of the
conventional art, and an ignition position (33) of the fuel in the
fuel-containing fluid ejected from the fuel-containing fluid supply
nozzle (12) into the furnace (4) is formed as shown in FIG. 29B,
which is a front view of the outlet part of the fuel-containing
fluid supply nozzle (12) as viewed from the furnace (4) side. After
the fuel is ignited at a surface of the ejection flow of the fuel
containing fluid (11), a flame that is formed gradually propagates
toward a central part of the ejection flow of the fuel-containing
fluid (11). FIG. 30 schematically shows a propagation behavior of
the flame inside the furnace (4) in a cross-sectional direction
along the ejection flow of the fuel-containing fluid (11) at the
fuel-containing fluid supply nozzle (12) in the burner of the
conventional art. An ignited region (32) is formed around an
unignited region (31) of conical shape.
[0006] The burner of circular cross section, shown in FIGS. 28 to
30, is frequently used in a so-called opposed firing configuration
in which the burners is disposed at each of a pair of opposing
furnace walls. Meanwhile, in so-called tangential firing in which
the fuel is combusted while the fuel-containing fluid is ejected
into the furnace (4) in directions of applying a rotation along a
furnace wall surface from outlets of a plurality of fuel-containing
fluid supply nozzles (12), an outlet shape of a transverse section
(section orthogonal to the flow of the fuel-containing fluid) of
each fuel-containing fluid supply nozzle (12) is made a square
shape or a rectangular shape close to a square shape in many
cases.
[0007] Burners, with which the outlet shape of the transverse
section (section orthogonal to the flow of the fuel-containing
fluid) of the fuel-containing fluid supply nozzle (12) is made a
rectangular shape, an elliptical shape, or a substantially
elliptical shape with major and minor axis parts, are disclosed in
the following Patent Documents 1 to 3.
[0008] Patent Document 1: Japanese Translation of International
Application (Kohyo) No. Sho 59-500981
[0009] Patent Document 2: Japanese Published Patent Application No.
Hei 8-226615
[0010] Patent Document 3: Japanese Published Patent Application No.
Hei 11-281009
DISCLOSURE OF THE INVENTION
Object(s) of the Invention
[0011] In general, a cross section of an outlet part of a
fuel-containing fluid supply nozzle (12) of a burner has a shape
close to a circular shape or a square shape, and there are cases
where, as shown in FIG. 30, a flame ignited at an outer side of a
fuel-containing fluid ejection flow in a furnace (4) must propagate
a considerable distance to reach a central part of the
fuel-containing fluid ejection flow. A distance in a
fuel-containing fluid (11) ejection flow direction from the
fuel-containing fluid supply nozzle (12) that is required for the
ignited flame to propagate to the central part of the fuel ejection
flow, in other words, an unignited distance L1' shown in FIG. 30 is
longer and an unignited region (31) is more expanded the larger a
diameter or a peripheral part of the fuel-containing fluid supply
nozzle (12). Although promotion of combustion in a reducing region
in a vicinity of the burner is important for suppressing NOx
generation in a combustion gas, expansion of the unignited region
(31) inhibits the NOx concentration suppression characteristic.
Expansion of the unignited region (31) also means that a combustion
time after ignition is short and causes lowering of combustion
efficiency.
[0012] Although increasing a burner capacity (decreasing a number
of burners) is an effective method for reducing cost and improving
operability, with the conventional art, when the burner capacity is
increased, a diameter or a length of an outer diameter part of the
fuel-containing fluid supply nozzle (12) becomes long and the
unignited region (31) expands, causing increase of NOx and lowering
of the combustion efficiency. This problem was due to the distance
from an ignited region (32) at a fuel-containing fluid ejection
flow surface to the central part of the fuel-containing fluid
ejection flow being large. Also, with the inventions described in
Patent Documents 1 to 3 where the outlet shape of the transverse
section (section orthogonal to the flow of the fuel-containing
fluid) of the fuel-containing fluid supply nozzle (12) is made a
rectangular shape, etc. that combines major and minor axis parts,
nothing is mentioned in regard to a countermeasure for the
expansion of the unignited region (31) due to increase of the
burner capacity and the resulting increase of NOx and lowering of
the combustion efficiency.
[0013] An object of the present invention is to provide a solid
fuel burner that is increased in capacity over the conventional art
and yet is suppressed in expansion of an unignited region to
prevent increase of NOx concentration in a combustion gas and
prevent lowering of combustion efficiency, a combustion equipment
and a boiler including the burner.
SUMMARY OF THE INVENTION
[0014] The above object of the present invention is achieved by the
following solutions.
[0015] A first aspect of the present invention provides a burner
including: a fuel-containing fluid supply nozzle (12) supplying a
fuel-containing fluid (11), containing a solid fuel and a medium
for transfer of the solid fuel, to an outlet part disposed on a
wall surface of a furnace (4) from a connecting part (10a) of a
fuel-containing fluid transfer flow passage (10) that transfers the
fluid (11); and one or more air supply nozzles (15) supplying
combustion air and disposed at an outer peripheral part of the
fuel-containing fluid supply nozzle (12); and where, from the
connecting part (10a) of the fluid transfer flow passage (10)
toward the outlet part disposed on the wall surface of the furnace
(4), a cross section of the fuel-containing fluid supply nozzle
(12) perpendicular to a flow of the fluid (11) has a rectangular,
elliptical, or substantially elliptical shape with major and minor
axis parts and, from the connecting part (10a) of the fluid
transfer flow passage (10) toward the outlet part, a size of the
major axis part of the cross section perpendicular to the flow of
the fluid (11) increases gradually along a direction of the flow of
the fluid (11) and a size of the minor axis part is unchanged.
[0016] A fourth aspect of the present invention provides the burner
according to the first aspect where the fuel-containing fluid
supply nozzle (12) has, in an interior thereof, fuel-containing
fluid guide plates (19) plurally partitioning the flow of the
fuel-containing fluid (11).
[0017] A fifth aspect of the present invention provides the burner
according to the fourth aspect where the fuel-containing fluid
guide plates (19) are disposed at a plurality of different
inclination angles with respect to a plane passing along a line
extending a central axis in the direction of the flow of the fluid
(11) in the fuel-containing fluid supply nozzle (12) toward the
furnace (4) and parallel to a shortest axis of the minor axis part
of the nozzle (12).
[0018] A sixth aspect of the present invention provides the burner
according to any of the first, fourth and fifth aspects where the
fuel-containing fluid supply nozzle (12) has, in an interior of the
outlet thereof, fuel-containing fluid direction changing guide
plates (21) forcibly changing a direction of ejection flow of the
fuel-containing fluid (11).
[0019] A seventh aspect of the present invention provides the
burner according to the sixth aspect where the fuel-containing
fluid direction changing guide plates (21) are disposed in a
plurality of mutually different directions with respect to planes
parallel to a plane passing along the line extending the central
axis of the fuel-containing fluid supply nozzle (12) toward the
furnace (4) and passing through a longest axis of the major axis
part of the nozzle (12).
[0020] An eighth aspect of the present invention provides the
burner according to the sixth aspect where the fuel-containing
fluid direction changing guide plates (21) for a portion of the
fuel-containing fluid (11) are disposed parallel to planes parallel
to a plane passing along the line extending the central axis of the
fuel-containing fluid supply nozzle (12) toward the furnace (4)and
passing through a longest axis of the major axis part of the nozzle
(12), and the fuel-containing fluid direction changing guide plates
(21) for another portion of the fuel containing fluid (11) are
disposed at an inclination angle with respect to planes parallel to
the plane passing along the line extending the central axis of the
fuel-containing fluid supply nozzle (12) toward the furnace (4) and
passing through the longest axis of the major axis part of the
nozzle (12).
[0021] A ninth aspect of the present invention provides the burner
according to the fourth aspect where the fuel-containing fluid
supply nozzle (12) is partitioned into a plurality of flow passages
by the fuel-containing fluid guide plates (19), and central axes of
the respective flow passages are disposed at the wall surface of
the furnace (4) at a plurality of mutually different inclination
angles with respect to planes parallel to a plane passing along the
line extending the central axis of the fuel-containing fluid supply
nozzle (12) toward the furnace (4) and passing through a longest
axis of the major axis part of the nozzle (12) outlet.
[0022] A tenth aspect of the present invention provides the burner
according to any of the first and fourth to ninth aspects where
fuel-containing fluid partitioning plates (22), capable of plurally
partitioning the outlet part of the fuel-containing fluid supply
nozzle (12), are disposed at the outlet part.
[0023] An eleventh aspect of the present invention provides the
burner according to any of the first and fourth to tenth aspects
where a flame stabilizer (17) with an L-shaped cross section is
disposed at the outlet part of the fuel-containing fluid supply
nozzle (12).
[0024] A twelfth aspect of the present invention provides the
burner according to the eleventh aspect where a guide plate (17a)
outwardly changing an ejection direction of the combustion air in a
periphery of the flame stabilizer (17) is disposed at a front end
of the L-shaped flame stabilizer (17).
[0025] A thirteenth aspect of the present invention provides the
burner according to any of the first and fourth to twelfth aspects
where a combustion air guide plate (15a), outwardly spreading an
ejection direction of the combustion air at an outer side of the
one or more combustion air supply nozzles (15) disposed at the
outer peripheral part of the nozzle (12) with respect to a fuel
ejection direction, is disposed at a front end of the
fuel-containing fluid supply nozzle (12).
[0026] A fourteenth aspect of the present invention provides the
burner according to any one of the first and fourth to thirteenth
aspects where a condenser (23), narrowing the flow passage of the
fuel-containing fluid (11) once and then expanding the flow passage
again, is disposed in an interior of the fuel-containing fluid
supply nozzle (12).
[0027] A fifteenth aspect of the present invention provides the
burner according to any one of the first and fourth to fourteenth
aspects where a fluid distribution plate (24) distributing the fuel
uniformly inside the fuel-containing fluid supply nozzle (12) is
disposed at an inlet part of the fuel-containing fluid supply
nozzle (12).
[0028] A sixteenth aspect of the present invention provides the
burner according to any of the first and fourth to fifteenth
aspects where a nozzle (41, 44), ejecting a liquid fuel or a gas
fuel that is an auxiliary fuel to a vicinity of the fluid (11)
ejected from the fuel-containing fluid supply nozzle (12), is
disposed at the vicinity of the fuel-containing fluid supply nozzle
(12).
[0029] A seventeenth aspect of the present invention provides a
combustion equipment where the burners according to any of the
first and fourth to sixteenth aspects are disposed in a plurality
of stages in an up/down direction at each of two opposing furnace
walls, and a plurality of burners disposed at each stage are
disposed respectively symmetrically in wall surface regions divided
in two at a central part of width in a horizontal direction of the
same furnace wall.
[0030] An eighteenth aspect of the present invention provides a
combustion equipment where the burners according to any of the
first and fourth to sixteenth aspects are disposed in the plurality
of stages in the up/down direction at each of the two opposing
furnace walls, and burners, which, among the plurality of burners
disposed in each stage of the same furnace wall, are adjacent each
other in the horizontal direction, are burners of the same
structure.
[0031] A nineteenth aspect of the present invention provides a
boiler including: a furnace wall formed by spirally winding a set
of water wall tubes (25) inclined with respect to a horizontal
direction; and where openings (26) of rectangular, elliptical, or
substantially elliptical shape are disposed in the furnace wall
along a longitudinal direction of the water wall tubes (25) and the
burner according to any of the first and fourth to sixteenth
aspects is mounted in each opening (26).
[0032] A twentieth aspect of the present invention provides a
boiler including: a furnace wall formed by a set of water wall
tubes (25) extending in a vertical direction; and where openings
(26) of rectangular, elliptical, or substantially elliptical shape
are disposed in the furnace wall along a longitudinal direction of
the water wall tubes (25) and the burner according to any of the
first and fourth to sixteenth aspects is mounted in each opening
(26).
EFFECT(S) OF THE INVENTION
[0033] According to the first aspect of the present invention,
expansion of an unignited region can be suppressed even if a burner
capacity is increased, an unignited distance can be reduced
effectively in comparison with the conventional art because the
fuel-containing fluid (11) spreads in the width direction even
after the fuel-containing fluid (11) is loaded into the furnace (4)
so that a cross-sectional area of the ejection flow of the
fuel-containing fluid (11) increases and a flow velocity decreases,
and also because the fuel-containing fluid (11) spreads inside the
furnace (4), a combustion space can be utilized effectively and a
practical furnace retention time is made long, thereby providing
effects of reducing NOx concentration in a combustion gas and
improving combustion efficiency. Also, the size of the minor axis
part of the fuel-containing fluid supply nozzle (12) is unchanged,
and this is effective for simplification of structure. Also, a flow
velocity at an upstream side of the fuel-containing fluid supply
nozzle (12) can be made high, and this is effective for preventing
backfiring in a case of a readily ignitable fuel, etc.
[0034] According to the fourth and fifth aspects of the present
invention, because the flow of the fuel-containing fluid (11) is
partitioned plurally by the fuel-containing fluid guide plates (19)
in the interior of the fuel-containing fluid supply nozzle (12),
the fuel-containing fluid (11) is supplied uniformly in the
direction in which the fuel-containing fluid supply nozzle (12)
expands from the fuel-containing fluid connecting part (10a) toward
the outlet part of the nozzle (12), and the effects of NOx
reduction, improvement in combustion efficiency, suppression of
flow velocity increase, minimization of pressure loss, and
suppression of wear of component parts are improved in comparison
with other those of the third aspect of the present invention.
[0035] According to the sixth aspect of the present invention,
effects of promoting dispersion of the fuel-containing fluid
ejection flow (20) inside the furnace (4) and promoting combustion
at a wake part of the furnace (4) are provided. According to the
seventh aspect of the present invention, because the
fuel-containing fluid guide plates (19) are respectively disposed
in mutually opposing directions with respect to the planes parallel
to the plane passing along the line extending the central axis of
the fuel-containing fluid supply nozzle (12) toward the furnace (4)
and passing through the longest axis of the major axis part of the
nozzle (12), the fuel-containing fluid (11) can be ejected into the
furnace (4) in two or more groups and the fuel-containing fluid
ejection flow (20) can thereby be divided into groups by a simple
structure to provide the effects of promoting the dispersion of the
fuel-containing fluid ejection flow (20) inside the furnace (4) and
promoting the combustion at the wake part of the furnace (4).
[0036] According to the eighth aspect of the present invention, by
dividing four fuel-containing fluid ejection flows (20), formed by
the fuel-containing fluid supply nozzle (12) and the
fuel-containing fluid guide plates (19) into two groups (20a, 20b)
and thereby making, for example, fuel-containing fluid ejection
flows (20a), adjacent a furnace side wall, rectilinear flows and
making fuel-containing fluid ejection flows (20b), not adjacent the
furnace side wall, be ejected upon applying an inclination with
respect to a horizontal direction, an effect of preventing ash
deposition by suppressing flame inflow to a vicinity of the furnace
side wall while maintaining promotion of combustion at the furnace
wake part by dispersion of the fuel is provided.
[0037] According to the ninth aspect of the present invention,
because the fuel-containing fluid (11) can be ejected into the
furnace (4) at mutually different angles with respect to the
horizontal direction or the vertical direction from the
fuel-containing fluid supply nozzle (12) and the fuel-containing
fluid ejection flow (20) can be varied in direction without using
parts inside the fuel-containing fluid supply nozzle (12) with
which pulverized coal or other solid fuel collides directly, wear
of parts can be suppressed effectively.
[0038] According to the tenth aspect of the present invention, the
fuel-containing fluid ejection flow (20) is partitioned by the
fuel-containing fluid partitioning plates (22) to be increased in
surface area, and radiant heat inside the furnace (4) is thereby
increased and a negative pressure region is formed at the wake side
of the fluid partitioning plates (22), thereby making a high
temperature gas in a periphery flow into the negative pressure
region to contribute to early ignition of the fuel, promote
combustion at a reducing region in the vicinity of the burner, and
effectively contribute to the reduction of the NOx concentration in
the combustion gas and the improvement in the combustion
efficiency.
[0039] According to the eleventh aspect of the present invention,
by disposing the flame stabilizer (17) with the L-shaped cross
section at the outlet part of the fuel-containing fluid supply
nozzle (12), a circular vortex is formed at the wake of the flame
stabilizer (17) and draws back the high-temperature combustion gas
to a vicinity of the flame stabilizer (17) to contribute to early
ignition of the fuel, promote combustion at the reducing region in
the vicinity of the burner, and effectively contribute to the
reduction of the NOx concentration in the combustion gas and the
improvement in the combustion efficiency in compassion with the
eleventh aspect of the invention.
[0040] According to the twelfth aspect of the present invention, by
the secondary air guide plate (17a) at the front end of the flame
stabilizer (17) of L-shaped cross section, the secondary air is
spread outward and the circular vortex at the wake of the flame
stabilizer (17) is enlarged, thereby increasing a recirculation
amount of the high-temperature combustion gas to further quicken
ignition of the fuel, promote combustion at the reducing region
near the burner, and effectively contribute to the reduction of the
NOx concentration in the combustion gas and the improvement in the
combustion efficiency in comparison with the eleventh aspect of the
invention.
[0041] According to the thirteenth aspect of the present invention,
by provision of the combustion air guide plate (15a) that spreads
the combustion air ejection direction at the outer side of the
combustion air supply nozzles (15) outward with respect to the
fuel-containing fluid ejection direction, the combustion air is
spread outward, thereby enlarging the reducing region at a central
part of the flame and effectively contributing to the reduction of
the NOx concentration in the combustion gas and the improvement in
the combustion efficiency.
[0042] According to the fourteenth aspect of the present invention,
the fuel in the vicinity of the flame stabilizer (17) is condensed
by the condenser (23) thereby contributing to early ignition of the
fuel to promote combustion at a reducing region in the vicinity of
the burner and effectively contributing to the reduction of the NOx
concentration in the combustion gas and the improvement in the
combustion efficiency.
[0043] According to the fifteenth aspect of the present invention,
the fuel concentration at the inlet part of the fuel-containing
fluid supply nozzle (12) is made uniform by the fluid distribution
plate (24) to suppress imbalance of concentration of the fuel
flowing into the respective flow passages partitioned by the
fuel-containing fluid guide plates (19), and this is effective for
NOx reduction and improvement in the combustion efficiency.
[0044] According to the sixteenth aspect of the present invention,
because the liquid fuel or the gas fuel is ejected to the burner
outlet, the fuel-containing fluid (11) that contains the solid fuel
can be ignited reliably.
[0045] According to the seventeenth aspect of the present
invention, by the burners according to any of the first and fourth
to sixteenth aspects being disposed in the plurality of stages in
the up/down direction at each of the opposing furnace walls of the
opposed firing type furnace (4) and by disposing the plurality of
burners of each stage respectively symmetrically at the wall
surface regions divided in two at the central part of width in the
horizontal direction of the same furnace wall, the directions of
the fluid ejection flows (20a, 20b) can be made left/right
symmetrical at a single furnace wall surface and good left/right
balance of flow and combustion states can be maintained in the
furnace (4).
[0046] According to the eighteenth aspect of the present invention,
by the burners according to any of the first and fourth to
sixteenth aspects being disposed in the plurality of stages in the
up/down direction at each of the two opposing furnace walls of the
opposed firing type furnace (4) and by making the burners, which,
among the plurality of burners disposed in each stage of the same
furnace wall, are adjacent each other in the horizontal direction,
burners of the same structure, collision of the fuel-containing
fluid ejection flows (20a, 20b) can be avoided, especially in a
furnace (4) of small capacity, to suppress localized concentration
of fuel and provide the effects of reducing the NOx concentration
in the combustion gas and improving the combustion efficiency.
[0047] According to the nineteenth aspect of the present invention,
by aligning a longitudinal direction of the water wall tubes (25)
with a longitudinal direction of the major axis parts of the
openings (26), a number of the spiral water wall tubes (25)
necessary for forming the openings (26) can be made small and an
economical boiler can be constructed with few processed and bent
parts in the water wall tubes (25). The number of the spiral water
wall tubes (25) necessary for forming the openings (26) can be
minimized to improve economy. Also, because the fuel-containing
fluid (11) spreads in the horizontal (width) direction of the
furnace (4), distribution of the fuel-containing fluid (11) in the
horizontal (width) direction of the furnace (4) is made uniform,
the practical furnace retention time is made longer, and the
effects of reducing the NOx concentration in the combustion gas and
improving the combustion efficiency are provided.
[0048] According to the twentieth aspect of the present invention,
because the rectangular openings (26) are installed on the furnace
wall along the arrangement of the water wall tubes (25) in the
vertical direction, by aligning the longitudinal direction of the
water wall tubes (25) with the longitudinal direction of the major
axis parts of the openings (26), an economical boiler can be
constructed with few processed and bent parts in the water wall
tubes (25).
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 shows explanatory diagrams of ignited regions of
burner outlets according to the present invention and a
conventional art.
[0050] FIG. 2 shows explanatory diagrams of unignited regions of
the burner outlets according to the present invention and the
conventional art.
[0051] FIG. 3 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 3A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 3B is a sectional view
taken on line A-A of FIG. 3A, and FIG. 3C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0052] FIG. 4 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 4A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 4B is a sectional view
taken on line A-A of FIG. 4A, and FIG. 4C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0053] FIG. 5 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 5A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner in a direction parallel to and passing
through a longest axis of a major axis part of an outlet part, FIG.
5B is a sectional view taken on line A-A of FIG. 5A, and FIG. 5C is
a front view of the outlet part of the burner as viewed from the
furnace side).
[0054] FIG. 6 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 6A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 6B is a sectional view
taken on line A-A of FIG. 6A, and FIG. 6C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0055] FIG. 7 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 7A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 7B is a sectional view
taken on line B-B of FIG. 7A, and FIG. 7C is a sectional view taken
on line A-A of FIG. 7A).
[0056] FIG. 8 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 8A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 8B is a sectional view
taken on line B-B of FIG. 8A, and FIG. 8C is a sectional view taken
on line A-A of FIG. 8A).
[0057] FIG. 9 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 9A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 9B is perspective view of
the burner, FIG. 9C is a sectional view taken on line B-B of FIG.
9A, and FIG. 9D is a sectional view taken on line A-A of FIG.
9A).
[0058] FIG. 10 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 10A is a sectional
view taken in a direction parallel to a plane passing along a line,
passing through a central axis of the burner and extending toward
the furnace, and passing through a longest axis of a major axis
part of an outlet part, FIG. 10B is a sectional view taken on line
A-A of FIG. 10A, and FIG. 10C is a front view of the outlet part of
the burner as viewed from the furnace side).
[0059] FIG. 11 is an explanatory diagram of effects of the
invention shown in FIG. 10.
[0060] FIG. 12 shows a configuration example of a burner according
to an embodiment of the present invention shown in FIG. 10 (FIG.
12A is a sectional view taken in a direction parallel to a plane
passing along a line, passing through a central axis of the burner
and extending toward the furnace, and passing through a longest
axis of a major axis part of an outlet part, FIG. 12B is a
sectional view taken on line A-A of FIG. 12A, and FIG. 12C is a
front view of the outlet part of the burner as viewed from the
furnace side).
[0061] FIG. 13 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 13A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 13B is a sectional view
taken on line A-A of FIG. 13A, and FIG. 13C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0062] FIG. 14 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 14A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 14B is a sectional view
taken on line A-A of FIG. 14A, and FIG. 14C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0063] FIG. 15 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 15A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 15B is a sectional view
taken on line A-A of FIG. 15A, and FIG. 15C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0064] FIG. 16 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 16A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 16B is a sectional view
taken on line A-A of FIG. 16A, and FIG. 16C is a front view of the
outlet part of the burner as viewed from the furnace side).
[0065] FIG. 17 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 17A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part, FIG. 17B is a sectional view
taken on line A-A of FIG. 17A, and FIG. 17C is a front view of the
outlet part of the burner as viewed from the furnace (4) side).
[0066] FIG. 18 shows a configuration example of a burner according
to an embodiment of the present invention (FIG. 18A is a sectional
view parallel to a fuel-containing fluid supply nozzle (12) surface
formed through a long edge of an outlet part of the nozzle (12)
(sectional view taken on line B-B of FIG. 18B), FIG. 18B is a
sectional view taken on line A-A of FIG. 18A, and FIG. 18C is a
front view of the outlet part of the burner as viewed from the
furnace side).
[0067] FIG. 19 shows an example where an oil supply nozzle is
installed at a central part of a fuel-containing fluid supply
nozzle.
[0068] FIG. 20 shows an example where gas supply nozzles are
installed in a periphery of a flame stabilizer.
[0069] FIG. 21 shows a front view (FIG. 21A) and a plan view (FIG.
21B) of a fuel-containing fluid supply nozzle.
[0070] FIG. 22 shows a front view (FIG. 22A) and a plan view (FIG.
22B) of a fuel-containing fluid supply nozzle of another
configuration.
[0071] FIG. 23 shows an example where a plurality of the
fuel-containing fluid supply nozzles, shown in FIG. 21, are
positioned in three stages in an up/down direction and four columns
in a horizontal direction on a single furnace wall surface.
[0072] FIG. 24 shows an example where a plurality of the
fuel-containing fluid supply nozzles, shown in FIGS. 21 and 22, are
positioned in three stages in an up/down direction and four columns
in a horizontal direction on a single furnace wall surface.
[0073] FIG. 25 shows another embodiment where a plurality of the
fuel-containing fluid supply nozzles, shown in FIG. 21, are
positioned in three stages in an up/down direction and four columns
in a horizontal direction on a single furnace wall surface.
[0074] FIG. 26 is a plan view of a furnace wall of a boiler in
which burners according to an embodiment of the present invention
are disposed.
[0075] FIG. 27 is a plan view of a furnace wall of a boiler in
which burners according to an embodiment of the present invention
are disposed.
[0076] FIG. 28 shows an example of a solid fuel burner according to
a conventional art (FIG. 28A is a side sectional view of the
burner, and FIG. 28B is a front view of the burner as viewed from a
furnace side).
[0077] FIG. 29A is a sectional view taken in a direction along an
ejection flow of a fuel-containing fluid at a fuel-containing fluid
supply nozzle in the burner of the conventional art, and FIG. 29B
is a front view of an outlet part of a fuel-containing fluid supply
nozzle as viewed from the furnace side.
[0078] FIG. 30 is schematic diagram of a flame propagation behavior
inside the furnace in a cross-sectional direction along the
ejection flow of the fuel-containing fluid at the fuel-containing
fluid supply nozzle in the burner of the conventional art.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0079] Embodiments of the present invention shall now be described
along with the drawings.
[0080] Basic concepts of the present invention shall now be
described using FIGS. 1 and 2. In FIG. 1, an ignition position (33)
in a furnace (4) using a fuel-containing fluid supply nozzle (12)
of a burner according to an embodiment shown in FIGS. 1A and 1B is
compared with that in a conventional art shown in FIGS. 10 and 1D.
FIG. 1A is a sectional view of the fuel-containing fluid supply
nozzle (12) of the burner according to the present embodiment taken
in an ejection flow direction of a fuel-containing fluid (11), FIG.
1B is a front view of an outlet part of the fuel-containing fluid
supply nozzle (12) of FIG. 1A as viewed from the furnace (4) side,
FIG. 1C is a sectional view of the fuel-containing fluid supply
nozzle (12) of the burner according to the conventional art taken
in the ejection flow direction of the fuel-containing fluid, and
FIG. 1D is a front view of the outlet part of the fuel-containing
fluid supply nozzle (12) as viewed from the furnace (4) side.
[0081] As shown in FIG. 1D, in the conventional art, the
ring-shaped ignition position (33) is present in a periphery of the
ejection flow of circular cross section of the fuel-containing
fluid (11) that is ejected from the fuel-containing fluid supply
nozzle (12) of the burner. Meanwhile, in the present embodiment,
the ignition position (33) is present in a periphery of the
ejection flow of rectangular cross section of the fuel-containing
fluid (11) that is ejected from the fuel-containing fluid supply
nozzle (12) of the burner as shown in FIG. 1B.
[0082] In the present embodiment, by making the shape of the outlet
part of the fuel-containing fluid supply nozzle (12) of the burner
a rectangular shape and reducing a length of a short edge, a length
L2 (FIG. 1B) from the ignition position (33) to a central part of
the ejection flow of the fuel-containing fluid (11) inside the
furnace (4) in a direction perpendicular to the ejection flow of
rectangular cross section of the fuel-containing fluid (11) is
reduced significantly in comparison with the length L2' (FIG. 1D)
from the ignition position (33) to the central part of the ejection
flow of the fuel-containing fluid (11) in the direction
perpendicular to the ejection flow of circular cross section.
[0083] FIG. 2 shows sectional views of the fuel-containing fluid
supply nozzle (12) of the burner showing that a distance (unignited
distance) L1 (FIG. 2A) that a flame propagates from the ignition
position (33) to the central part of the fuel ejection flow in an
ejection flow direction of the fuel-containing fluid (11) from the
fuel-containing fluid supply nozzle (12) in the embodiment is
reduced in comparison with the unignited distance L1' (FIG. 2B) in
the conventional art. In the present embodiment, in accordance with
the reduction of the distance L2 from the ignition position (33) to
the central part of the ejection flow of the fuel-containing fluid
(11) in the direction perpendicular to the ejection flow of
rectangular cross section in comparison with the distance L2' of
the conventional art, the unignited distance L1 is reduced
significantly in comparison with the unignited distance L1' of the
conventional art.
[0084] FIG. 3 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 3A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part (sectional view taken on line B-B of
FIG. 3B), FIG. 3B is a sectional view taken on line A-A of FIG. 3A,
and FIG. 3C is a front view of the outlet part of the burner as
viewed from the furnace (4) side.
[0085] A cylindrical fuel-containing fluid flow passage (10) is
connected via a connecting part (10a) of circular cross section to
the fuel-containing fluid supply nozzle (12) having a rectangular
cross section and has an adequate configuration for forming the
ejection flow of rectangular cross section from the fuel-containing
fluid supply nozzle (12) into the furnace (4). Even after the
fuel-containing fluid (11) is loaded into the furnace (4), the
fuel-containing fluid (11) spreads along the ejection flow
directions and a cross-sectional area of the ejection flow of the
fuel-containing fluid (11) expands while a flow velocity decreases,
thereby effectively reducing the unignited distance L1 shown in
FIG. 2 further. Also, because the fuel-containing fluid (11)
spreads inside the furnace (4), a combustion space can be utilized
effectively and a practical furnace retention time is made long,
thereby contributing effectively to reduction of NOx concentration
in a combustion gas and improvement in combustion efficiency. A
combustion air sleeve (15) of rectangular cross section and a
burner throat (16) of rectangular cross section are disposed in a
periphery of the fuel-containing fluid supply nozzle (12).
[0086] FIG. 4 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 4A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part (sectional view taken on line B-B of
FIG. 4B), FIG. 4B is a sectional view taken on line A-A of FIG. 4A,
and FIG. 4C is a front view of the outlet part of the burner as
viewed from the furnace (4) side.
[0087] In the burner shown in FIG. 4, the cross section of the
burner in the direction perpendicular to the ejection flow of the
fuel-containing fluid (11) has an elliptical shape, and
configurations of other parts are the same as those of the burner
shown in FIG. 3.
[0088] Although as cross-sectional shapes in a vertical direction
of the burner (direction perpendicular to the ejection flow of the
fuel-containing fluid (11)), the representative shapes of
rectangular and elliptical were shown in FIGS. 3 and 4,
respectively, the same effects as those mentioned above can be
obtained even when a similar shape, such as a shape with which
short sides of a rectangle have an arcuate shape, an expanded
rhombus, etc., is employed.
[0089] FIG. 5 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 5A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part (sectional view taken on line B-B of
FIG. 5B), FIG. 5B is a sectional view taken on line A-A of FIG. 5A,
and FIG. 5C is a front view of the outlet part of the burner as
viewed from the furnace (4) side.
[0090] In the burner shown in FIG. 5, whereas a size of the major
axis part gradually increases along the flow direction of the
fuel-containing fluid (11) from the fuel-containing fluid
connecting part (10a) of the fuel-containing fluid supply nozzle
(12) toward the outlet part, a size of a minor axis part gradually
decreases along the direction of flow of the fuel-containing fluid
(11), and configurations of other parts are the same as those of
the burner shown in FIG. 3.
[0091] A characteristic of the burner structure shown in FIG. 5 is
that increase of the flow velocity of the fuel-containing fluid
(11) from the fuel-containing fluid connecting part (10a) toward
the outlet part of the fuel-containing fluid supply nozzle (12) can
be suppressed to minimize pressure loss and suppress wear of
component parts inside the fuel-containing fluid supply nozzle
(12).
[0092] FIG. 6 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 6A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part (sectional view taken on line B-B of
FIG. 6B), FIG. 6B is a sectional view taken on line A-A of FIG. 6A,
and FIG. 6C is a front view of the outlet part of the burner as
viewed from the furnace (4) side.
[0093] In the burner shown in FIG. 6, fuel-containing fluid guide
plates (19) are disposed so that the fuel-containing fluid (11)
flowing inside the fuel-containing fluid supply nozzle (12) is
uniformly supplied in directions in which the fuel-containing fluid
supply nozzle (12) expands along the ejection flow direction, and
configurations of other parts are the same as those of the burner
shown in FIG. 5. In the present example, three fuel-containing
fluid guide plates (19) are installed, and to make the
fuel-containing fluid (11) spread uniformly in accordance with the
spreading of the fuel-containing fluid supply nozzle (12), a
central guide plate (19) is disposed along the central axis and
guide plates (19) at both sides that sandwich the central guide
plate (19) are disposed at angles a and p with respect to a
vertical section passing through the central axis.
[0094] Because the flow of the fuel-containing fluid (11) flowing
inside the fuel-containing fluid supply nozzle (12) is partitioned
plurally by the fuel-containing fluid guide plates (19), the
fuel-containing fluid (11) is spread uniformly according to the
spreading of the fuel-containing fluid supply nozzle (12) from the
fuel-containing fluid connecting part (10a) toward the outlet part
of the fuel-containing fluid supply nozzle (12) and can be
combusted without imbalance. Also, by the fuel-containing fluid
(11) being spread uniformly, the effects of suppression of
localized increase of flow velocity, minimization of pressure loss,
and suppression of wear of component parts are improved over those
of the configuration shown in FIG. 5.
[0095] FIG. 7 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 7A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part, FIG. 7B is a sectional view taken on
line B-B of FIG. 7A, and FIG. 7C is a sectional view taken on line
A-A of FIG. 7A.
[0096] In the burner shown in FIG. 7, the fuel-containing fluid
guide plates (19) are disposed in the same manner as in the burner
shown in FIG. 6 so that the fuel-containing fluid (11) flowing
inside the fuel-containing fluid supply nozzle (12) is uniformly
supplied in directions in which the fuel-containing fluid supply
nozzle (12) expands along the flow direction, and in the section
taken on line A-A of FIG. 7A, fuel-containing fluid direction
changing guide plates (21a) that change the flow of the fluid (11)
downward with respect to a plane along a line, passing through the
central axis of the fuel-containing fluid supply nozzle (12) and
extending toward the furnace (4), and passing through the longest
axis of the major axis part of the outlet part are installed at the
burner outlet part, and in the section taken on line B-B of FIG.
7A, fuel-containing fluid direction changing guide plates (21b)
that change the flow of the fluid (11) upward with respect to the
abovementioned plane are installed at the burner outlet part. Four
fuel-containing fluid ejection flows 20 (20a, 20b) formed by the
fuel-containing fluid supply nozzle (12) and the fuel-containing
fluid guide plates (19) are formed to downwardly inclining
fuel-containing fluid ejection flows (20a) and upwardly inclining
fuel-containing fluid ejection flows (20b) by the above-mentioned
fuel-containing fluid direction changing guide plates (21a, 21b).
By the burner configuration shown in FIG. 7, dispersion of the
fuel-containing fluid ejection flow (20) inside the furnace (4) is
promoted to provide an effect of promoting combustion at a wake
part of the furnace (4).
[0097] FIG. 8 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 8A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part, FIG. 8B is a sectional view taken on
line B-B of FIG. 8A, and FIG. 8C is a sectional view taken on line
A-A of FIG. 8A.
[0098] In the burner shown in FIG. 8, the fuel-containing fluid
guide plates (19) are disposed in the same manner as in the burner
shown in FIG. 7 so that the fuel-containing fluid (11) flowing
inside the fuel-containing fluid supply nozzle (12) is uniformly
supplied in directions in which the fuel-containing fluid supply
nozzle (12) expands along the flow direction, and in the section
taken on line A-A of FIG. 8A, fuel-containing fluid direction
changing guide plates (21a) that rectify and make the flow of the
fluid (11) rectilinear with respect to a plane along a line,
passing through the central axis of the fuel-containing fluid
supply nozzle (12) and extending toward the furnace (4), and
passing through the longest axis of the major axis part of the
outlet part are installed at the burner outlet part, and in the
section taken on line B-B of FIG. 8A, fuel-containing fluid
direction changing guide plates (21b) that change the flow of the
fluid (11) upward with respect to the abovementioned plane are
installed at the burner outlet part. Four fuel-containing fluid
ejection flows 20 (20a, 20b) formed by the fuel-containing fluid
supply nozzle (12) and the fuel-containing fluid guide plates (19),
are formed to fuel-containing fluid ejection flows (20a) in a
rectilinear direction and fuel-containing fluid ejection flows
(20b) that are upwardly directed ejection flows by installation of
the above-mentioned fuel-containing fluid direction changing guide
plates (21a, 21b).
[0099] In a case where the fuel-containing fluid direction changing
guide plates (21a) are not installed and only the guide plates
(21b) that change the direction are installed, the same
fuel-containing fluid ejection flows (20a, 20b) are formed.
[0100] For example, by making fuel-containing fluid ejection flows,
close to a water wall side at a side wall side of the furnace (4),
rectilinear flows and making fuel-containing fluid that are not
close to the water wall side at the side wall side of the furnace
(4) flows that are oblique with respect to a central side of the
furnace by the burner configuration shown in FIG. 8, the dispersion
of the fuel-containing fluid ejection flow (20) inside the furnace
(4) is promoted to maintain the effect of promoting the combustion
at the wake part of the furnace (4) and provide an effect of
suppressing inflow of a flame to a vicinity of the side wall of the
furnace (4) to prevent ash deposition.
[0101] FIG. 9 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 9A is a sectional view
taken in a direction parallel to a plane passing through a central
axis of the burner and passing through a longest axis of a major
axis part of an outlet part, FIG. 9B is perspective view of the
burner, FIG. 9C is a sectional view taken on line B-B of FIG. 9A,
and FIG. 9D is a sectional view taken on line A-A of FIG. 9A.
[0102] In the burner shown in FIG. 9, the fuel-containing fluid
guide plates (19) are disposed in the same manner as in the burner
shown in FIG. 7 so that the fuel-containing fluid (11) flowing
inside the fuel-containing fluid supply nozzle (12) is uniformly
supplied in directions in which the fuel-containing fluid supply
nozzle (12) expands along the flow direction. A front side of an
inlet part of the fuel-containing fluid supply nozzle (12) has a
parallelepiped shape, one side surface (12a) of the fuel-containing
fluid supply nozzle (12) leads to the outlet of the fuel-containing
fluid supply nozzle (12) while being disposed obliquely downward
along the flow direction and the other side surface (12b) leads to
the outlet while being disposed obliquely upward along the flow
direction.
[0103] By this configuration, an obliquely downwardly directed
fuel-containing fluid ejection flow (20a) is formed at a portion
close to the side surface (12a) of the fuel-containing fluid supply
nozzle (12) as shown in FIG. 9D, and an obliquely upwardly directed
fuel-containing fluid ejection flow (20d) is formed at a portion
close to the side surface (12b) of the fuel-containing fluid supply
nozzle (12) as shown in FIG. 9C. From two central flow passages
into which the fuel-containing fluid supply nozzle (12) is
partitioned by the fuel-containing fluid guide plates (19), a
fuel-containing fluid ejection flow (20b) having an ejection flow
direction intermediate the fuel-containing fluid ejection flow
(20a) and the central line and a fuel-containing fluid ejection
flow (20c) having an ejection flow direction intermediate the
fuel-containing fluid ejection flow (20d) and the central line are
formed.
[0104] Although the effects of the burner configuration of FIG. 9
are equivalent to those of the burner shown in FIG. 7, because the
fuel-containing fluid direction changing guide plates (21) are not
used to change the ejection direction of the fuel-containing fluid
(11), a problem of wear that is of concern with the guide plates
(21) does not occur.
[0105] FIG. 10 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 10A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 10B), FIG. 10B is a sectional view taken on line A-A of
FIG. 10A, and FIG. 10C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0106] Fuel-containing fluid partitioning plates 22, perpendicular
to the flow of the fuel-containing fluid (11) and partially
blocking the flow, are disposed at the outlet part of the
fuel-containing fluid supply nozzle (12). The fuel-containing fluid
ejection flow (20) is partitioned into four by the fuel-containing
fluid partitioning plates (22) as shown in FIG. 11. By the
partitioning, the fuel-containing fluid ejection flow (20)
increases in surface area, the radiant heating inside the furnace
(4) increases, negative pressure regions (22a) are formed at the
wake side of the fuel-containing fluid partitioning plates (22),
and high-temperature gas in the periphery flows into the negative
pressure regions (22a) as indicated by arrows in the figure.
Increase of the radiant heating and inflow of the high-temperature
gas into the negative pressure regions (22a) both contribute to
early ignition of the fuel, and combustion in a reducing region in
a vicinity of the burner is promoted to contribute effectively to
reduction of the NOx concentration of the combustion gas and
improvement in the combustion efficiency.
[0107] FIG. 12 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 12A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 12B), FIG. 12B is a sectional view taken on line A-A of
FIG. 12A, and FIG. 12C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0108] The fuel-containing fluid partitioning plates (22),
perpendicular to the flow of the fuel-containing fluid (11) and
partially blocking the flow, are disposed at the outlet parts of
the fuel-containing fluid guide plates (19) at the outlet part of
the fuel-containing fluid supply nozzle (12). Because the
fuel-containing fluid (11) is supplied uniformly inside the
fuel-containing fluid supply nozzle (12) by the fuel-containing
fluid guide plates (19), the reduction of NOx and improvement in
the combustion efficiency are realized more effectively.
[0109] FIG. 13 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 13A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 13B), FIG. 13B is a sectional view taken on line A-A of
FIG. 13A, and FIG. 13C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0110] A flame stabilizer (17) with an L-shaped cross section is
installed at the outlet part of the fuel-containing fluid supply
nozzle (12). Because a circular vortex (not shown) is formed at a
wake of the flame stabilizer (17) and draws back the
high-temperature combustion gas to the vicinity of the flame
stabilizer (17), the configuration contributes to early ignition of
the fuel and promotes combustion in the reducing region in the
vicinity of the burner to effectively contribute to reduction of
the NOx concentration in the combustion gas and improvement in the
combustion efficiency.
[0111] FIG. 14 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 14A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 14B), FIG. 14B is a sectional view taken on line A-A of
FIG. 14A, and FIG. 14C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0112] A secondary air guide plate (17a) that outwardly spreads
ejection directions of a secondary air is installed at a front end
of the flame stabilizer (17) of L-shaped cross section shown in
FIG. 14. By the secondary air being spread outward by the guide
plate (17a), the vortex flow (not shown) at the wake of the flame
stabilizer (17) is enlarged, a recirculation amount of the
high-temperature gas is increased, ignition of the fuel is
quickened further, and combustion in the reducing region in the
vicinity of the burner is promoted to effectively contribute to
reduction of the NOx concentration in the combustion gas and
improvement in the combustion efficiency.
[0113] FIG. 15 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 15A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 15B), FIG. 15B is a sectional view taken on line A-A of
FIG. 15A, and FIG. 15C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0114] In the burner shown in FIG. 15, a tertiary air guide plate
(15a) that outwardly spreads ejection directions of a tertiary air
is installed at a front end of a secondary air sleeve (15). By the
tertiary air being spread outward, a reducing region at a center
part of the flame is enlarged to effectively contribute to
reduction of the NOx concentration in the combustion gas and
improvement in the combustion efficiency.
[0115] FIG. 16 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 16A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner and passing through a longest axis of a
major axis part of an outlet part (sectional view taken on line B-B
of FIG. 16B), FIG. 16B is a sectional view taken on line A-A of
FIG. 16A, and FIG. 16C is a front view of the outlet part of the
burner as viewed from the furnace (4) side.
[0116] In the burner shown in FIG. 16, a fuel-containing fluid
condenser (23), combining a triangular prism gradually increasing
in cross-sectional area from an upstream side and an oppositely
directed triangular prism gradually decreasing in cross-sectional
area at a downstream side, is installed inside the fuel-containing
fluid supply nozzle (12). The fuel in the vicinity of the flame
stabilizer (17) is condensed by the fuel-containing fluid condenser
(23) and this contributes to early ignition of the fuel, promotes
combustion in the reducing region near the burner, and thereby
effectively contributes to reduction of the NOx concentration in
the combustion gas and improvement in the combustion
efficiency.
[0117] FIG. 17 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 17A is a sectional
view taken in a direction parallel to a plane passing through a
central axis of the burner in a direction parallel to and passing
through a longest axis of a major axis part of an outlet part
(sectional view taken on line B-B of FIG. 17B), FIG. 17B is a
sectional view taken on line A-A of FIG. 17A, and FIG. 17C is a
front view of the outlet part of the burner as viewed from the
furnace (4) side.
[0118] A fuel-containing fluid condenser (23') combining a
triangular prism gradually increasing in cross-sectional area at an
upstream side, a quadrangular prism at an intermediate part, and an
oppositely directed triangular prism gradually decreasing in
cross-sectional area at a downstream side, is installed inside the
fuel-containing fluid supply nozzle (12). In the present
configuration, delamination is suppressed by making an angular
variation around the condenser (23') small and a fuel condensing
effect is thereby promoted to heighten the NOx reducing effect and
improve the combustion efficiency.
[0119] Although effective configuration examples of the condenser
(23, 23') are shown in FIGS. 16 and 17, the same effects are
obtained even when a condenser with a similar structure, such as a
triangular prism, etc., is employed.
[0120] FIG. 18 shows a structural example of a burner according to
an embodiment of the present invention. FIG. 18A is a sectional
view parallel to a fuel-containing fluid supply nozzle (12) surface
formed through a long edge of an outlet part of the nozzle (12)
(sectional view taken on line B-B of FIG. 18B), FIG. 18B is a
sectional view taken on line A-A of FIG. 18A, and FIG. 18C is a
front view of the outlet part of the burner as viewed from the
furnace (4) side.
[0121] In FIG. 18, a dam-like fluid distribution plate (24) is
disposed at an inlet part of the fuel-containing fluid supply
nozzle (12). The fuel-containing fluid (11) collides once with an
upstream side of the dam-like fluid distribution plate (24) and,
after being dispersed uniformly in the direction of a long edge of
the fuel-containing fluid supply nozzle (12), is guided uniformly
into the four flow passages partitioned by the fuel-containing
fluid guide plates (19) inside the fuel-containing fluid supply
nozzle (12) and supplied into the furnace (4) while being
maintained in a uniform state.
[0122] FIG. 19 shows an example where an oil supply nozzle (41) is
installed at a central part of the fuel-containing fluid supply
nozzle (12). FIG. 19A is a sectional view taken in a direction
parallel to a plane passing through a central axis of the burner
and passing through a longest axis of a major axis part of an
outlet part (sectional view taken on line B-B of FIG. 19B), FIG.
19B is a sectional view taken on line A-A of FIG. 19A, and FIG. 19C
is a front view of the outlet part of the burner as viewed from the
furnace (4) side.
[0123] FIG. 20 shows an example where a gas ejection part,
connected from a gas introduction tube (42) to gas supply nozzles
(44) via a horizontal tube (43), is installed in a periphery of the
flame stabilizer (17).
[0124] FIG. 20A is a sectional view taken in a direction parallel
to a plane passing through a central axis of the burner and passing
through a longest axis of a major axis part of an outlet part
(sectional view taken on line B-B of FIG. 20B), FIG. 20B is a
sectional view taken on line A-A of FIG. 20A, and FIG. 20C is a
front view of the outlet part of the burner as viewed from the
furnace (4) side.
[0125] FIG. 21 shows, for a burner structure, a front view as
viewed from the furnace (4) side (FIG. 21A) and a plan view (FIG.
21B) of the fuel-containing fluid supply nozzle (12), with which
the cross-sectional shape perpendicular to the flow of the
fuel-containing fluid (11) flowing inside the fuel-containing fluid
supply nozzle (12) of the burner is rectangular, in a case where
the fuel-containing fluid supply nozzle (12) is positioned with its
long edge side directed in an up/down direction.
[0126] As viewed from the furnace (4) front side, the
fuel-containing fluid ejection flows (20a, 20b) from the
fuel-containing fluid supply nozzle (12) shown in FIG. 21 are
formed obliquely toward mutually opposite sides in the horizontal
direction to the left and right with respect to a plane
perpendicular to the furnace wall surface in upper and lower
directions of the long edge side of the nozzle (12). The forming of
the present fuel-containing fluid ejection flows is achieved by
applying the burner structure of FIG. 7 or FIG. 9.
[0127] FIG. 22 shows, for a burner structure, a front view as
viewed from the furnace (4) side (FIG. 22A) and a plan view (FIG.
22B) of the fuel-containing fluid supply nozzle (12), with which
the cross-sectional shape perpendicular to the flow of the
fuel-containing fluid (11) flowing inside the fuel-containing fluid
supply nozzle (12) of the burner is rectangular, in a case where
the fuel-containing fluid supply nozzle (12) is positioned with its
long edge side directed in an up/down direction.
[0128] As viewed from the furnace (4) front side, one
fuel-containing fluid ejection flow (20b) from the fuel-containing
fluid supply nozzle (12) shown in FIG. 22 is formed obliquely to
the horizontal direction with respect to a plane perpendicular to
the furnace wall surface in upper and lower directions of the long
edge side of the nozzle (12) and the other fuel-containing fluid
ejection flow (20c) is formed perpendicular to the furnace wall
surface. The forming of the present fuel-containing fluid ejection
flows is achieved by applying the burner structure of FIG. 8.
[0129] FIG. 23 shows an example where a plurality of the
fuel-containing fluid supply nozzles (12), shown in FIG. 21, are
positioned in three stages in the up/down direction and four
columns in the horizontal direction on a single furnace wall
surface. Fuel-containing fluid supply nozzles (12) forming ejection
flows (20a, 20b) in the same directions as the nozzles (12) shown
in FIG. 21 are disposed at a right half of the single furnace wall,
and fuel-containing fluid supply nozzles (12) forming ejection
flows (20a, 20b) at mirror symmetric positions with respect to the
fuel-containing fluid supply nozzles (12) shown in FIG. 21 are
disposed at a left half of the furnace wall. By configuring the
directions of the fuel-containing fluid ejection flows (20a, 20b)
to be left/right symmetrical on the single furnace wall surface, a
good left/right balance of flow and combustion states can be
maintained in the furnace (4).
[0130] As long as the ejection flows (20a, 20b) from the
fuel-containing fluid supply nozzles (12), disposed distributedly
at left and right halves of a single furnace wall, are formed at
mirror symmetrical positions, the directions of the fuel-containing
fluid ejection flows (20a, 20b) from the nozzles (12) do not
necessary have to be as illustrated.
[0131] FIG. 24 shows an example where a plurality of the
fuel-containing fluid supply nozzles (12) are positioned in three
stages in the up/down direction and four columns in the horizontal
direction on a single furnace wall surface, with the
fuel-containing fluid supply nozzles (12) shown in FIG. 22 being
disposed mirror symmetrically at respective end columns at the left
and right sides and the fuel-containing fluid supply nozzles (12)
shown in FIG. 21 being disposed mirror symmetrically at two central
columns. By aligning the burners with the rectilinear
fuel-containing fluid ejection flows (20c) and the oblique
fuel-containing fluid ejection flows (20b) along and adjacent the
water walls of the side wall of the furnace (4), and aligning the
fuel-containing fluid ejection flows (20a, 20b), which are inclined
obliquely to the respective sides, along and adjacent the center,
the dispersion within the furnace (4) is promoted to maintain the
effect of promoting the combustion at the wake part of the furnace
(4) while providing the effect of suppressing inflow of the flame
to the vicinity of the side wall of the furnace (4) to prevent ash
deposition.
[0132] FIG. 25 shows an example where the fuel-containing fluid
supply nozzles (12) that are all the same and form the
fuel-containing fluid ejection flows (20a, 20b) shown in FIG. 21
are disposed as the fuel-containing fluid supply nozzles (12) of
all of the burners on the single furnace wall. The present
embodiment provides a configuration with which collision of the
fuel-containing fluid ejection flows (20a, 20b) can be avoided,
especially in a furnace (4) of small capacity, and localized
concentration of fuel is suppressed to effectively reduce the NOx
concentration in the combustion gas and improve the combustion
efficiency.
[0133] By selecting appropriately from the burner structures of
FIGS. 21 to 25 in accordance with furnace dimensions, burner
configurations, and other conditions, optimal combustion
characteristics can be realized.
[0134] FIG. 26 is a plan view of a furnace wall of a boiler in
which burners according to an embodiment of the present invention
are disposed. In FIG. 26, in a boiler having spiral water wall
tubes (25) on the furnace wall, rectangular openings (26) are
installed and the various burners described as the embodiments of
the present invention are mounted along an arrangement of the water
wall tubes (25) that is oblique with respect to the horizontal
direction. By disposing the openings (26) along the spiral water
wall tubes (25), a number of the water wall tubes (25) necessary
for forming the openings (26) can be minimized to improve
economy.
[0135] As described above, a combustion equipment configured from
the respective embodiments of the present invention has a
characteristic of enabling the combustion space to be utilized
effectively because the fuel-containing fluid ejection flows (20)
spread inside the furnace (4), and with the configuration shown in
FIG. 26, because the fuel-containing fluid ejection flows (20a,
20b) spread in the horizontal (width) direction of the furnace (4),
a distribution of the fuel-containing fluid (11) in the horizontal
(width) direction of the furnace (4) is made uniform and the
practical furnace retention time is made even longer, thereby
effectively contributing to the reduction of NOx concentration in
the combustion gas and improvement in combustion efficiency.
[0136] FIG. 27 is a plan view of a furnace wall of a boiler in
which burners according to an embodiment of the present invention
are disposed. In FIG. 27, in a boiler having water wall tubes (25)
extending in the vertical direction on the furnace wall,
rectangular openings (26) are installed and the various burners
described as the embodiments of the present invention are mounted
along the arrangement of the water wall tubes (25). By disposing
the openings (26) along the water wall tubes (25), the number of
the water wall tubes (25) necessary for forming the openings (26)
can be minimized to improve economy.
[0137] In the present configuration, by using the burners shown in
FIGS. 7 to 9 so that the directions of the fuel-containing fluid
ejection flows (20a, 20b) are directed in mutually different
directions to promote the dispersion of the fuel-containing fluid
(11) even in the horizontal (width) direction of the furnace (4),
the dispersion of the fuel-containing fluid (11) in the entirety of
the furnace is promoted, thereby effectively contributing to NOx
reduction and improvement in combustion efficiency.
[0138] An oil or a gas is generally used as an auxiliary fuel in a
burner, and even when supply nozzles for such fuels are installed
at apart of the burners according to the embodiments of the present
invention, the characteristics and effects of the burners according
to the embodiments of the present invention are maintained.
INDUSTRIAL APPLICABILITY
[0139] As a burner structure capable of following a trend toward
burners of large capacity while reducing cost without lowering
combustion performance, the present invention is high in future
industrial applicability.
DESCRIPTION OF THE SYMBOLS
[0140] 3 windbox, 4 furnace, 10 fuel-containing fluid flow passage,
10a fuel-containing fluid connecting part, 11 fuel-containing
fluid, 12 fuel-containing fluid supply nozzle
13 secondary air, 14 tertiary air, 15 combustion air sleeve, 15a
tertiary air guide plate, 16 burner throat, 17 flame stabilizer,
17a secondary air guide plate, 19 fuel-containing fluid guide
plate, 20, 20a, 20b, 20c, 20d fuel-containing fluid ejection flow,
21a, 21b fuel-containing fluid direction changing guide plate, 22
fuel-containing fluid partitioning plate, 22a negative pressure
region, 23, 23' condenser, 24 fluid distribution plate, 25 water
wall tube, 26 opening, 31 unignited region, 32 ignited region, 33
ignition position, 41 oil supply nozzle, 42 gas introduction tube,
43 horizontal tube, 44 gas supply nozzle, L1 unignited distance, L2
distance from ignition position to central part of fuel-containing
fluid ejection flow
* * * * *