U.S. patent application number 12/175963 was filed with the patent office on 2009-02-12 for plasma ignition burner.
Invention is credited to Fei CAI, Peng LIU, Yuwang MIAO, Tao NIU, Yingjie QIAN, Xinguang WANG, Yupeng WANG, Wenbo YU, Xiaoyong ZHANG.
Application Number | 20090038518 12/175963 |
Document ID | / |
Family ID | 40259296 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090038518 |
Kind Code |
A1 |
LIU; Peng ; et al. |
February 12, 2009 |
PLASMA IGNITION BURNER
Abstract
A plasma ignition burner. The plasma ignition burner has at
least two stages of burner barrels and a plasma generator for
igniting the pulverized coal in a first stage burner barrel of the
at least two stages of burner barrels. The burning flame of the
former stage burner barrel ignites the pulverized coal in the next
stage burner barrel, or further burns with the supplemented air in
the next stage burner barrel. The axial direction of said plasma
generator is parallel to the direction along which the
pulverized-coal-contained air flow enters into the first stage
burner barrel and at the same time, parallel to the axis of the
burner barrels.
Inventors: |
LIU; Peng; (Shandong,
CN) ; ZHANG; Xiaoyong; (Shandong, CN) ; QIAN;
Yingjie; (Shandong, CN) ; WANG; Xinguang;
(Shandong, CN) ; YU; Wenbo; (Shandong, CN)
; CAI; Fei; (Shandong, CN) ; MIAO; Yuwang;
(Shandong, CN) ; NIU; Tao; (Shandong, CN) ;
WANG; Yupeng; (Shandong, CN) |
Correspondence
Address: |
LADAS & PARRY LLP
224 SOUTH MICHIGAN AVENUE, SUITE 1600
CHICAGO
IL
60604
US
|
Family ID: |
40259296 |
Appl. No.: |
12/175963 |
Filed: |
July 18, 2008 |
Current U.S.
Class: |
110/263 |
Current CPC
Class: |
F23D 1/00 20130101; F23D
2207/00 20130101; F23D 2201/10 20130101; F23D 2201/20 20130101 |
Class at
Publication: |
110/263 |
International
Class: |
F23D 1/00 20060101
F23D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 19, 2007 |
CN |
200710137008.2 |
Jul 19, 2007 |
CN |
200720146244.6 |
Claims
1. A plasma ignition burner, comprising at least two stages of
burner barrels and a plasma generator for igniting the pulverized
coal in a first stage burner barrel of said at least two stages of
burner barrels, wherein the burning flame of the former stage
burner barrel ignites the pulverized coal in the next stage burner
barrel, or further burns with the supplemented air in the next
stage burner barrel, wherein the axial direction of said plasma
generator is parallel to the direction along which the
pulverized-coal-contained air flow enters into the first stage
burner barrel and at the same time, parallel to the axis of the
burner barrels.
2. The plasma ignition burner according to claim 1, further
comprising a bending tube for guiding the pulverized-coal-contained
air flow into said at least two stages of burner barrels, wherein
one end of the bending tube on the side of the burner barrels is
parallel to the axis of the burner barrels, and said plasma
generator is inserted into the first stage burner barrel through
the wall of said bending tube along the axial direction of the
burner barrels.
3. The plasma ignition burner according to claim 2, further
comprising a guide plate arranged along the axis of the bending
tube, wherein one end of the guide plate on the side of the burner
barrels is parallel to the axis of the plasma generator.
4. The plasma ignition burner according to claim 3, wherein said
guide plate extends to the vicinity of the inlet of the first stage
burner barrel.
5. The plasma ignition burner according to claim 4, wherein the
ends of said plasma generator and said guide plate are arranged on
the axis of the burner barrels, or deflected form the axis of the
burner barrels for a predetermined distance.
6. The plasma ignition burner according to claim 3, wherein the
shape of the section plane of said guide plate is planar.
7. The plasma ignition burner according to claim 3, wherein the
shape of the section plane of said guide is bending surface.
8. The plasma ignition burner according to claim 2, wherein an
anti-abrasion protecting sleeve is provided to protect said plasma
generator.
9. The plasma ignition burner according to claim 8, wherein the
windward surface of said anti-abrasion protecting sleeve is
V-shaped.
Description
TECHNICAL FIELD
[0001] The present invention relates to pulverized coal burning
technical field, and particular to a plasma ignition burner.
BACKGROUND ART
[0002] Coal fired power generation is a main electricity generation
manner adopted by different countries at present. Ignition is a
main aspect of the burning process of the boiler. With the
enlargement of the capacity of the boiler, how to accomplish the
starting process of the boiler rapidly and economically becomes an
important problem to be imminently solved.
[0003] Plasma ignition technology has been developed recently to
replace the oil ignition manner which consumes a lot of burning
oil.
[0004] In order to be able to ignite inferior coal, the
conventional plasma igniting system adopts the so-called
"precombustion chamber" technology. The precombustion chamber is
constructed to keep the temperature of the burner barrel, normally
by attaching a layer of fire-resistant material to the internal of
the firebox. The chamber wall of the precombustion chamber has very
high temperature through initial heating, which aids in (even
independently) igniting the fuel. The precombustion chamber is long
(about 2 meters) and through the action of the plasma, gasifies the
pulverized coal in the pulverized-coal-contained air flow entering
into the precombustion chamber, thereby generating a lot of
burnable gas, mainly CO et al. And then, the thermal energy
released when the burnable gas burns is used to ignite the
succeeding pulverized coal. This is also a hierarchical ignition
manner, but since the temperature in the precombustion chamber is
too high, the pulverized coal easily clinkers inside and therefore
can not be used further.
[0005] In order to overcome the above problem, a new structure of
hierarchical burner barrel has been proposed. As shown in FIG. 1,
the plasma ignition burner comprises multi stage burner barrels,
such as a first stage burner barrel 104, a second stage burner
barrel 106, a third stage burner barrel 108, a fourth stage burner
barrel 110, et al (the number of the stages may be either more than
four stages or less than four stages depending on the power and the
size of the space). The pulverized-coal-contained air flow entering
from pulverized-coal-contained air flow inlet 102 (as shown by the
broad arrow in FIG. 1) is divided into two ways by spacer 116 and
respectively enters into the first stage burner barrel 104 and the
second stage burner barrel 106. A plasma generator is inserted into
the first stage burner barrel 104 along the axial direction of the
multi stage burner barrels and ignites the
pulverized-coal-contained air flow entering into the first stage
burner barrel 104, thereby generating the first stage pulverized
coal flame A. The generated flame further ignites the
pulverized-coal-contained air flow in the second stage burner
barrel, thereby forming the second stage pulverized coal flame B.
At the same time, the air flow entering from air inlet 114 (as
shown by the narrow arrow in FIG. 1) enters into the third stage
burner barrel 108 through the third inlet 120 and supplements
oxygen for the second stage pulverized coal flame which was not
sufficiently burned, thereby forming a third stage pulverized coal
flame C. The air may also enter into the fourth stage burner barrel
through the fourth inlet 122 to further supplement oxygen. At the
same time, the air flow flows in the space between the external
wall of the former stage burner barrel and the burner external
barrel 118 before entering into the next stage burner barrel,
thereby serving for cooling the burner barrels so as to prevent
clinkering.
[0006] In the above technology, the plasma generator is inserted
along the axial direction of the burner barrels and the
pulverized-coal-contained air flow inlet and the air flow are both
arranged to be perpendicular to the axis of the burner barrels.
That is, the direction of the plasma flame is perpendicular to the
direction of the air flow entering into the first stage burner
barrel. Therefore, it is necessary to add guide plate (not shown)
to deflect the air flow to be parallel. Similarly, the direction
along which the second stage pulverized coal enters into the second
stage burner barrel is also perpendicular to the direction of the
flame injected from the first stage burner barrel, so it is also
necessary to add guide plate to make the directions to be parallel.
However, the guide plate can not deflect the air flow completely
due to the limitation of the space. Since the two air flows can not
be absolutely parallel, the entering air flow will blow the plasma
flame (or the former stage flame) deflected, which causes the
temperature of the barrel wall increasing and the pulverized coal
clinkering.
[0007] In addition, in this technology, because the
pulverized-coal-contained air flow and the air flow both enters in
the direction perpendicular to the burner barrels, on the section
plane perpendicular to the burner barrels, the concentration of the
pulverized coal and the velocity of the air flow, et al. are not
uniform, thereby affecting the burning quality.
[0008] Afterward, in order to make it easy to arrange on the spot,
a plasma ignition burner constructed as shown in FIG. 2 is used. To
be concise, only the pulverized-coal-contained air flow inlet 102,
the first stage burner barrel 104 and the second stage burner
barrel 106 are shown in the figure and the structures corresponding
to the air inlet 114, the burner external barrel 118, the third
stage burner barrel and the fourth stage burner barrel in FIG. 1.
The pulverized-coal-contained air flow entering from inlet 102 is
then divided into two parts by the barrel wall of the first stage
burner barrel, in which the central part enters into the first
stage burner barrel 104, the peripheral part advances along the
space between the first stage burner barrel and the external barrel
202 (the pulverized-coal-contained air flow inlet 102 is provided
thereon), and enters into the second stage burner barrel from the
second inlet 204 of the second stage burner barrel. As shown in the
figure, the plasma generator is inserted along the radial direction
of the burner and the pulverized-coal-contained air flow is blown
into along the axial direction of the burner barrels, the two
directions of which are still perpendicular. Under the action of
the pulverized-coal-contained air flow, the plasma flame is blown
deflected, causing the temperature of the side to which the plasma
flame is deflected extra high so that clinker is formed.
[0009] Therefore, a new technology is needed to further prevent the
pulverized coal from clinkering on the wall of the burner
barrels.
SUMMARY OF THE INVENTION
[0010] Therefore, an object of the present invention is to provide
a plasma generator which can relieve the problem of clinkering. It
can be seen from the above description of the prior art, the fact
that there exists an angle between the inserting direction of the
plasma generator (that is, the direction of the plasma flame) and
the direction of the pulverized-coal-contained air flow is a reason
of the clinkering problem. Therefore, with respect to the above
object, the gist of the present invention is to rearrange the
pulverized-coal-contained air flow inlet and the plasma generator,
so as to make the direction along which the
pulverized-coal-contained air flow enters into the first stage
burner barrel consistent with the direction of the plasma
flame.
[0011] In addition, in order to further solve the problem of
clinkering, it is necessary to make the pulverized-coal-contained
air flow or air flow of the next stage as consistent with the
pulverized coal flame of the former stage as possible.
[0012] For this purpose, the present invention provides a plasma
ignition burner, comprises at least two stages of burner barrels
and a plasma generator for igniting the pulverized coal in a first
stage burner barrel of said at least two stages of burner barrels,
wherein the burning flame of the former stage burner barrel ignites
the pulverized coal in the next stage burner barrel, or further
burns with the supplemented air in the next stage burner barrel,
characterized in that the axial direction of said plasma generator
is parallel to the direction along which the
pulverized-coal-contained air flow enters into the first stage
burner barrel and at the same time, parallel to the axis of the
burner barrels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be described in details with
reference to the accompanying drawings. In the drawings, the same
reference sighs are used for the same or corresponding technical
features.
[0014] FIG. 1 is a sectional view schematically illustrating a
plasma ignition burner of the prior art;
[0015] FIG. 2 is a partial sectional view schematically
illustrating another plasma ignition burner of the prior art;
[0016] FIG. 3 is a partial sectional view schematically
illustrating the first embodiment of the plasma ignition burner
according to the present invention;
[0017] FIG. 4 is a sectional view along A-A line in FIG. 3;
[0018] FIG. 5 is a partial sectional view schematically
illustrating the second embodiment of the plasma ignition burner
according to the present invention;
[0019] FIG. 6 is a sectional view illustrating the structure of the
axial swirl pulverized coal burner of the prior art.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 3 illustrates the partial sectional view schematically
illustrating the first embodiment of the plasma ignition burner
according to the first aspect of the present invention. To be
concise, this figure also only illustrates the
pulverized-coal-contained air flow inlet 102, the first stage
burner barrel 104 and the second stage burner barrel 106 similar to
those in FIG. 2. Since the structure of the multi-stage structure
of burner barrels has been described as above, it is not repeated
here. What should be noted is that, as described in the part
"BACKGRAOUND ART", the stage number of the burner barrels into
which the pulverized-coal-contained air flow enters, the stage
number of the burner barrel into which the air directly enters and
the total stage number of the burner barrels are not limited and
can be determined depending on power request and the size of the
space. The total number of the stages may be from two stages to
three, four or more stages and the air flow as shown in FIG. 1 may
be also pulverized-coal-contained air flow depending on the
application occasions.
[0021] The key of the present invention is to make the insertion
direction of the plasma generator 302 parallel to the direction
along which the pulverized-coal-contained air flow enters into the
first stage burner barrel 104 and at the same time, parallel to the
axis of the burner barrels. Thus, the pulverized-coal-contained air
flow enters into the burner barrels parallel to the axis of the
burner barrels, without distribution asymmetry of the pulverized
coal on the section plane of the burner barrels due to the inertia
of the pulverized-coal-contained air flow. Moreover, since the
injection direction of the plasma flame of the plasma generator is
consistent with the direction along which the
pulverized-coal-contained air flow enters into the burner barrels,
the plasma flame will not be blown defected to the wall of the
burner barrels. The above two points effectively alleviate the
problem of clinkering on the wall of the burner barrels.
[0022] In the first embodiment shown in FIG. 3, the above technical
solution is achieved by providing bending tube 308 to guide the
pulverized-coal-contained air flow and inserting the plasma
generator 302 into the first stage burner barrel 104 through the
wall of said bending tube along the axial direction of the burner
barrels. In order to make the distribution on the section plane as
uniform as possible without defection to one side due to
centrifugal force when the pulverized-coal-contained air flow
enters into the straight burner barrel at the position of A-A
section plane, the radian of the bending tube 308 should be as
gentle as possible. However, as long as there exists radian,
centrifugal force can not be avoided and the pulverized coal will
deflect to one side in the burner barrel. In order to avoid this
problem, in one preferred embodiment, a guide plate 306 is arranged
along the axis of the bending tube 308 and one end of the guide
plate on the side of the burner barrel is parallel to the axis of
the plasma generator, and even extends to the vicinity of the inlet
310 of the first stage burner barrel 104. At the same time, the
plasma generator 302 and the end of the guide plate 306 are both
arranged on the axis of the burner barrel (of course, the position
of the end of the guide plate 306 may be deflected relative to the
axis of the burner barrel to some extent). Thus, the guide plate
306 not only changes the flow direction of the
pulverized-coal-contained air flow to make it parallel to the
plasma flame, but also concentrates part of the pulverized coal in
the vicinity of the central axis of the burner and the plasma flame
by the centrifugal separation effect, so as to increase the
concentration of the pulverized coal entering into the central
barrel, which aids in the ignition. Compared with the structure
shown in FIG. 1, only one guide plate is used to simultaneously
change the flowing direction of the pulverized-coal-contained air
flow entering into the respective stage burner barrels, the
structure is simple and the resistance is relatively small. Since
the space inside the bending head is large, the shape of the
bending plate may be planar and may be various bending surface (an
example is shown in FIG. 4) so as to further increase the
concentration of the pulverized coal entering into the central
barrel.
[0023] As shown in FIG. 3, a large part of the plasma generator 302
exposes to the pulverized-coal-contained air flow. In order to
prevent the plasma generator from being abraded by the
pulverized-coal-contained air flow, anti-abrasion protecting sleeve
(such as ceramics sleeve) can be used to protect the plasma
generator. Moreover, in order to reduce the resistance, the
windward surface of the sleeve may be made V-shaped.
[0024] Compared with the burner inserted along the radial direction
in FIG. 2, in addition to solving the problem of clinkering, this
burner also has stronger ignition capacity. Specifically, the
reason is as follows. The plasma flame is positioned on the central
line of the burner and since the central barrel is circle, the
ignition capacity of the plasma flame for respective directions is
the same, the flame is uniform and the transmission capacity is
strong. On the other hand, if the plasma flame is arranged on one
side of the central barrel of the burner, the temperature of the
flame on one side of the plasma flame will be high and that on the
other side is low. In this case, if inferior coal is burned,
ignition will even fail.
[0025] In the first embodiment as described above, the
concentrating of the pulverized coal in the central barrel of the
burner depends on the concentrating action of the guide plate 306
in the bending tube 308. However, due to the limitation of the
space, the concentration in the central barrel can not be increased
without limitation, which affects the effect of ignition. For this
purpose, the second embodiment according to the present invention
as shown in FIG. 5 is provided as the second aspect of the present
invention.
[0026] To be concise, FIG. 5 only illustrates the components
corresponding to those in FIGS. 2 and 3, that is, the first stage
burner barrel 104 and the burner internal barrel 202. As described
in the above embodiment, inside the burner internal barrel 202,
more stages of burner barrels can be arranged after the first stage
burner barrel 104. And outside the burner internal barrel 202,
there may be components corresponding to the burner external barrel
118 and multi stages of burner barrels after the burner internal
barrel and inside the burner external barrel 118.
[0027] In this embodiment, the pipe for supplying the
pulverized-coal-contained air flow branches into two pipes, that
is, primary pipe 508 and branch pipe 502. The primary pipe 508 may
be connected to the burner internal barrel 202 in a conventional
way or by adopting the bending tube 308 in the first embodiment. At
the same time, the central barrel 510 is guided from the first
stage burner barrel 104 to be connected to the branch pipe 502.
Similarly, the connection between the branch pipe 502 and the
central barrel 510 may adopt the conventional way or a second
bending tube 512 similar to the bending tube 308 in the first
embodiment and wherein, the guide plate 306 (not shown in FIG. 5)
in the first embodiment can also be used. The arrangement manner of
the plasma generator 302 may also be similar to the first
embodiment.
[0028] In this way, the concentration of the pulverized coal
entering into the central barrel and further entering into the
first stage burner barrel may be made relatively high by directly
guiding the pulverized-coal-contained air flow into the central
barrel using the branch tube, so as to aid in the ignition. As a
preferred embodiment, it is necessary to adjust the amount of the
entering pulverized-coal-contained air flow, and/or increase the
concentration of the pulverized coal in the
pulverized-coal-contained air flow entering into the plasma
ignition burner as high as possible. For this purpose, an adjuster
may be arranged on the branching point of the primary pipe and the
branch pipe for flexibly adjusting the amount of the pulverized
coal entering into the branch tube.
[0029] As a variation of the above-described solution, if there are
three or more stages of burner barrels guiding the
pulverized-coal-contained air flow in the burner, the respective
stages of burner barrels may be distributed between the central
barrel and the burner internal barrel. For example, if there are
three stages of burner barrels, the pulverized coal in the first
stage burner barrel and the second stage burner barrel of the
plasma ignition burner may be guided in simultaneously through the
central barrel and the branch pipe (in this case, the central
barrel and the internal structure thereof is similar to that shown
in FIG. 2, with only the burner internal barrel in FIG. 2 changing
to the central barrel in FIG. 5) and the pulverized coal in the
third stage burner barrel enters from the primary pipe. Inversely,
the pulverized coal in the first stage burner barrel of the plasma
ignition burner may be guided in through the central barrel and the
branch pipe and the pulverized coal in the second and the third
stage burner barrels may enter from the primary pipe.
[0030] In a preferred embodiment, a valve 504 may be provided in
the branch pipe, which is turned on in the starting ignition stage
and the low-load stable combustion stage of the burner and turned
off after the ignition is completed and the combustion of the
burner becomes stable. This valve 504 may also be designed to be
incorporated with the adjuster 506, so that the adjuster serves as
an adjuster and a branch tube valve simultaneously.
[0031] It can be seen from the above description of the second
embodiment, the gist of this embodiment is to increase the
concentration of the pulverized coal in the first stage burner
barrel by using the branch tube. It is neither limited to ignite
using the plasma generator, nor limited to provide the plasma
generator along the axial direction of the burner barrels.
Therefore, the detail of various aspects of the second embodiment
can be either combined or not combined with those of the first
embodiment. Specifically, the ignition device may be oil gun
besides the plasma generator and the arrangement manner thereof can
be insertion along any direction besides axial insertion, including
radial insertion and slanting insertion.
[0032] In the above-described solutions, since the branch tube is
arranged and the adjustor is attached, the flowing velocity of the
pulverized-coal-contained air flow and the concentration of the
pulverized coal in the central barrel of the burner can be
independently adjusted, so that the optimum ignition working
condition can be achieved.
[0033] In addition, for those old type burners which have been
amounted on the spot, a convenient and low-cost reconstructing
means can be provided by using the above-described second
embodiment, so that the present invention can be applied.
[0034] For example, the whirling type pulverized coal burner
adopted by many burning coal firepower electricity generator has a
central barrel and the mixture of the pulverized coal and the air
is sent into the hearth from the external of the central barrel.
For example, LNASB axial swirl pulverized coal burner (refer to
FIG. 6) developed by Mitsui Babcock Energy Ltd in the eighties of
20th century adopts this kind of structure. In this structure, the
oil gun is inserted into the central barrel 602 and the pulverized
coal sent into the hearth from the external of the central barrel
is ignited by the flame of the oil gun. For this kind of burner, if
the reconstruction of the plasma ignition technology is to be
directly performed, it is necessary to remove the structure of the
central barrel 602, which will cause the concentration distribution
of the pulverized coal and the air velocity inside the burner to be
changed greatly and will affect the original performance of the
burner. However, this problem can be solved by adopting the second
embodiment of the present invention. At the time of reconstructing
the plasma technology, it is simply necessary to reconstruct the
central barrel 602 to the first stage burner barrel 104, the
central barrel 510, the ignition device (such as the plasma
generator 302) and the branch tube 502 connected thereto as shown
in FIG. 5. And it is unnecessary to make any reconstruction for the
original mechanism of the pulverized-coal-contained air flow of the
burner (that is, the structure from the primary air to the tertiary
air tube shown in FIG. 6), thereby making the performance as
consistent with the original burner as possible.
[0035] The above-described reconstruction manner forms a
third-stage burner (that is, the first stage burner barrel, the
central barrel and the external barrel). In fact, if possible, a
two-stage burner may be formed only by the central barrel and the
external barrel, without the first stage burner barrel added. In
addition, more stages of burner barrel may be added in the central
barrel, or more stages of burner barrel may be added in the
external barrel.
[0036] In addition, the ignition device may be any kind of ignition
device either in the original burner, or in the reconstructed
burner, including oil gun and plasma ignition device, et al.
[0037] The preferred embodiments of the present invention are
described with reference to the accompanying drawings in the above.
Apparently, the present invention is not limited to the specific
details as described above and various changes or substitutions can
be made, which also falls within the protection scope of the
present invention.
* * * * *