JP3495490B2 - Pulverized fuel combustion burner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized fuel combustion burner having a fuel distributor and comprising a burner rich in fuel and a burner thin in fuel. 2. Description of the Related Art An example of a pulverized coal burning burner as a conventional pulverized fuel combustion burner will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a vertical side view of the conventional pulverized coal-fired burner, and FIG. 11 is a front view of the same. [0003] In these figures, 01 is a pulverized coal conveying pipe, 02 is a pulverized coal mixture, 03 is a distributor, 04 is a burner, 05 is a pulverized coal pipe, 06 is a conker burner, 07 is a weak burner, and 08 is a secondary burner. Air, 09 is a burner style box, 10
Denotes a pulverized coal nozzle, and 11 denotes a secondary air nozzle. [0004] The burner 04 is constructed integrally with a conch burner 06 having a high pulverized coal concentration and a weak burner 07 having a low pulverized coal concentration. The conch burner 06 and the weak burner 07 are each composed of a pulverized coal pipe 05 arranged in the center, a square burner- like box 09 surrounding the periphery thereof, a square pulverized coal nozzle 10 connected to the outlet, and a secondary air nozzle 11. Is done. [0005] The pulverized coal mixture 02 conveyed through the pulverized coal conveying pipe 01 together with the primary air hits the collision plate 03a of the distributor 03, and is divided into thick fine powder and light fine powder to the conc burner 06 and the weak burner 07. Respectively distributed and supplied, through the pulverized coal pipe 05 and the pulverized coal nozzle 10,
After being injected into the furnace, it is mixed and diffused with the secondary air 08 also injected through the secondary air nozzle 11, and burns. As described above, in the conventional pulverized coal-fired burner, the pulverized coal mixture 02 is divided into a high-concentration mixture and a low-concentration mixture by the distributor 03, and the conc
By burning lead to 6 and Week burner 07, it is possible to suppress the NO _x generation, because light portions to stabilize the combustion in the dark portion becomes as secondary combustion, which stabilizes combustion together both It is. [0007] In the above-mentioned conventional pulverized coal-fired burner, the primary air / coal ratio in the distributor 03 is close to 2.0 even with a highly concentrated air-fuel mixture. . In the case of a flame-retardant fuel, since the primary air / coal ratio has a maximum flame propagation speed near 1.0, the conventional flame tends to be unstable. Further, since the pulverized coal mixture 02 is not particularly rectified, when it is injected through the pulverized coal nozzle 10, the mixture of air and pulverized coal becomes non-uniform, resulting in poor ignition and flammability. There was also. Further, a stagnation flow of the pulverized coal mixture 02 is generated in a bend portion and a deformed portion in the tip of the burner nozzle, and the pulverized coal is deposited on the stagnation portion. In this case, the internal combustion engine receives strong radiant heat and ignites, causing burner nozzle burnout and spreading to the entire burner. It is an object of the present invention to provide a preferable burner which solves the above-mentioned problems of the conventional pulverized coal-fired burner, stabilizes combustion, and prevents burner burnout. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a fuel distributor for separating finely divided fuel into a rich fuel mixture, and a fuel mixture having a high fuel concentration. And a second burner nozzle for guiding and burning a fuel mixture having a low fuel concentration, wherein the fuel distributor is a cyclone-shaped distributor, and the first burner nozzle is a cyclone-shaped distributor. of the near the stop of the burner nozzles, it rectification block on an upstream side and a downstream side
The present invention provides a pulverized fuel combustion burner in which four or six rows are provided at equal angular pitches and the rectification blocks are combined to rectify a fuel-air mixture. In the present invention, a cyclone-shaped distributor is adopted, and the pulverized coal mixture is reliably separated into a mixture having a high concentration and a mixture having a low concentration by its excellent separation performance. In the first burner nozzle which is responsible for the higher mixture, the swirling force of the cyclone remains up to the burner outlet to create an uneven flow of the mixture, and rectifies the pulverized coal concentration distribution so as not to deteriorate at the burner ejection part. It is intended to be covered by blocks. When the rectifying block is provided near the cyclone, the swirling force of the cyclone is weakened, the cyclone efficiency is reduced, and a mixture having a high concentration of pulverized coal may not be obtained. In this case, the rectification block is provided at an equal angular pitch of 4 in the upstream side and the downstream side in the vicinity of the throttle portion of the first burner nozzle. Rows or six rows are provided, and the flow straightening blocks are combined to obtain a preferable and uniform flow velocity distribution. An embodiment of the present invention will be described with reference to FIG. In the figure, 02 is a pulverized coal mixture,
13 is a cyclone-shaped distributor, 14 is a rich mixture, 15 is a low mixture, 16 is a first burner for the rich mixture 14, and 17 is a second burner for a low mixture 15
, A first burner nozzle 18 for the rich mixture 14, 19 a second burner nozzle for the low-concentration mixture 15, 20 an upstream rectification block, 21 a downstream rectification block, and 25 a 1 is the inside of the tube of the burner 16, 28 is the length of the upstream rectification block 20, 29 is the length of the downstream rectification block 21, 30 is the burner throttle section, and 31 is an inner cylinder for introducing a low-concentration air-fuel mixture. . In the embodiment of the present invention in which the respective parts are configured as described above, the pulverized coal mixture 02 conveyed by the primary air is swirled by the cyclone-shaped distributor 13 as indicated by arrows in the figure. Is generated, and is separated into a rich mixture 14 having a high concentration and a mixture 15 having a low concentration. The rich mixture 14 is introduced into the furnace via a first burner 16 for the rich mixture 14, and the lean mixture 15 is introduced via a second burner 17 for a low-concentration mixture 15. And ignites and burns into the furnace. The fuel distribution rate is adjusted in accordance with the cyclone performance.
It is to be. Fuel distribution ratio (fuel amount of rich mixture 14 having high concentration / fuel amount of pulverized coal mixture 02) is 90%
, The primary air / coal ratio becomes about 1.0, and the flame of the flame-retardant fuel is stabilized. The rich mixture 14 in the first burner 16 for the rich mixture 14 is supplied to a cyclone-shaped distributor 13.
Gives a turning force. The swirled high-concentration rich mixture 14 is supplied to a rectifying block 20 provided near the burner throttle 30,
Rectification is performed at 21, and the air flow velocity distribution becomes substantially equal at the cross section of the outlet of the first burner nozzle 18, upper, middle, and lower. This point will be described later in detail with reference to examples and the like. On the other hand, in the second burner nozzle 19 for the air-fuel mixture 15 having a low concentration, there is almost no swirling flow even if no rectifying block is provided on the second burner 17 side, and the air flow velocity distribution is substantially uniform. As described above, according to the present embodiment, the second
The first burner 16 in which the swirling flow of the cyclone may remain as well as the burner 17 of the first embodiment also eliminates the stagnation flow in the burner, and the pulverized coal mixture is uniformly distributed from the first and second nozzles 18 and 19. Since the pulverized coal is ejected, pulverized coal does not accumulate in the passage or in the nozzle, and there is no danger of burning of the nozzle or the like. As described above, a case where the rectifying blocks 20 and 21 are not provided is a comparative example in which a stable jet flow of the first burner nozzle 18 is obtained.
An embodiment provided with 21 will be described below with reference to FIGS. [0021] Incidentally, these, FIG. 4 is present the air flow velocity distribution measurement position in the first burner nozzle 18 outlet portion underlying the following description. That is, in FIG. 4, reference numeral 22 denotes the upper part of the pipe, 23 denotes the center of the pipe, and 24 denotes the flow velocity distribution measurement position at the lower part of the pipe. Here, the inner diameter of the first burner nozzle 18 (same for the second burner nozzle 19) was 112 mm. Comparative Example FIG. 5 shows rectifying blocks 20 and 2
1 is an air flow distribution when none of the above is provided;
This is shown as a comparative example. The flow velocity of the air injected from the first burner nozzle 18 for the rich mixture is low at the center 23 of the pipe and high at the upper part 22 and the lower part 24 of the pipe. The upper part of the tube was more than three times faster than the center of the tube, and had an uneven air flow velocity distribution. Although not shown in the drawings and the like, the fuel distribution shows the same tendency as the air flow velocity distribution. (Embodiment 1) Embodiment 1 will be described with reference to FIGS. 2A, 3A and 6. FIG. 2A shows a cross section taken along line II-II of FIG. 1, and FIG. 3A shows a cross section taken along line III-III of FIG.
This point is common to the other embodiments shown below as FIGS. 2b to 3d and 3b to 3d. In the first embodiment, the upstream rectification block 20 is mounted on the wall surface of the pipe 25 by up, down, left, right, 90 °.
Four rows are arranged at a pitch, and the rectification blocks 21 on the downstream side are also arranged in four rows above, below, left, and right in the same arrangement. In this embodiment, the width 26 of the rectification blocks 20, 21 is 4.5 m.
m, the height 27 is 15 mm, and the lengths 28 and 29 are 100 mm for the upstream rectifying block 20 and 120 mm for the downstream rectifying block 21 . Note that the width, height, and length are all the same in other embodiments described later. In the present embodiment in which the rectifying blocks 20 and 21 are arranged as described above, the measured air velocity distribution is shown in FIG.
Shown in The flow velocity in the lower part 24 of the pipe is the fastest, and then in the center 23 of the pipe, the flow rate in the upper part 22 is the slowest. It can be seen that the difference between the highest and lowest flow speeds was smaller than in the comparative example without the rectification block, and the flow rate was made uniform. (Embodiment 2) Embodiment 2 will be described with reference to FIGS. 2B, 3B and 7. FIG. The upstream rectifying block 20 is the same as that of the first embodiment.
Same as above, arrange 4 rows at 90 ° pitch, top, bottom, left, right,
The mounting positions of the downstream rectifying blocks 21 are shifted by 30 ° from the first embodiment, and are arranged in four rows at 90 ° pitch.
Upstream rectification block 20 and downstream rectification block 21
Shall be staggered. FIG. 7 shows an air flow velocity distribution measured in the present embodiment in which the rectifying blocks 20 and 21 are arranged as described above. The flow velocity is the slowest at the center 23 of the pipe and the same at the same level between the lower part 24 and the upper part 22 of the pipe. It can be seen that the difference between the highest and the lowest is smaller than that of the first embodiment, and the difference is more uniform. (Embodiment 3) Embodiment 3 will be described with reference to FIGS. 2c, 3c and 8. FIG. The rectification block 20 on the upstream side is 60
6 rows arranged at equal intervals at ° pitch, 2 rectification blocks on the downstream side
1 is the same as that of the first embodiment, and four rows are arranged at 90 ° pitches of upper, lower, left and right, and the left and right are rectifying blocks 20 on the upstream side.
And the downstream rectification block 21 are at the same level, and the upper and lower sides are staggered. FIG. 8 shows the air flow velocity distribution measured in the present embodiment in which the rectification blocks 20, 21 are arranged in this manner. The flow velocity of the pipe center 23 and the pipe upper part 22 is at the same level and the pipe lower part 24 is faster. Compared with the second embodiment, the lower part 24 of the pipe was faster, but the difference between the center of the pipe and the upper part of the pipe was almost eliminated. It can be seen that the equalization is progressing more and more. Fourth Embodiment A fourth embodiment will be described with reference to FIGS. 2D, 3D and 9. The upstream rectifying block 20 is the same as that of the third embodiment.
In the same manner as in the above, six rows are arranged at a pitch of 60 °, and the rectifying blocks 21 on the downstream side are arranged in six rows in the same arrangement as the rectifying blocks on the upstream side. FIG. 9 shows the air flow velocity distribution measured in the present embodiment in which the rectifying blocks 20 and 21 are arranged as described above. The flow velocity is the same at the upper part 22 and at the lower part 24 of the pipe and slightly higher than at the center 23 of the pipe, but at almost all three points. It can be seen that the flow velocity is the most uniform among the above-described embodiments. The embodiment has been described above. As is clear from comparison with the comparative example, the rectifying block 2
0 and 21 are arranged near the throttle portion 30 of the first burner nozzle 18 on the upstream side and on the downstream side at equal angular pitches in four rows or six rows, respectively.
It can be seen that by providing the rows , the flow in the pipe is made uniform and a stable flow is obtained. In each of the above embodiments, the primary air / coal ratio was around 1.0, and the fuel distribution rate was as in the third embodiment.
Was slightly lower at 80%, but was about 90% in the other examples. As described above, according to the present invention, the distributor connected to the burner nozzle is formed into a cyclone shape so that the mixture can be divided into a mixture having a high concentration and a mixture having a low concentration. By squirting the mixture with a high concentration from the upstream side and the mixture with a low concentration from the downstream side into the furnace, stable ignition can be performed even for a flame-retardant fuel (primary air / coal ratio is 1). .
0) and the flammability is improved. [0043] Further to near the stop portion of the high first burner nozzles of concentration, it rectification block on an upstream side and a downstream side
By providing four or six rows at equal angular pitches and rectifying the fuel mixture by combining the rectification blocks, the distribution of the air flow velocity and the distribution of the fuel ejected from the burner nozzles become uniform, resulting in stable ignition and good flame holding. Further, since the air flow velocity distribution and the fuel distribution become uniform, the stagnation flow of the air-fuel mixture is eliminated, the accumulation of fuel can be prevented, and burnout of the burner can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a burner according to an embodiment of the present invention. 2 is a sectional view taken along line II-II of FIG.
(C) and (d) relate to different embodiments. FIG. 3 is a sectional view taken along the line III-III in FIG.
(B), (c), and (d) correspond to FIG. 2 and relate to different embodiments. FIG. 4 is an explanatory view showing a measurement position of an air flow velocity distribution in the embodiment of FIG. 1; FIG. 5 is an explanatory diagram showing an air flow velocity distribution of a comparative example according to the embodiment of the present invention. FIG. 6 is an explanatory diagram showing an air flow velocity distribution of the first example according to the embodiment of the present invention. FIG. 7 is an explanatory diagram showing an air flow velocity distribution of a second example according to the embodiment of the present invention. FIG. 8 is an explanatory diagram showing an air flow velocity distribution of a third example according to the embodiment of the present invention. FIG. 9 is an explanatory diagram showing an air flow velocity distribution of a fourth example according to the embodiment of the present invention. FIG. 10 is a side view of a conventional burner. 11 is a front view as viewed from the arrow XI-XI in FIG. 10; [Description of Signs] 02 Pulverized coal mixture 14 Rich mixture 15 Low concentration mixture 16 First burner 17 Second burner 18 First burner nozzle 19 Second burner nozzle 20 Upstream rectifying block 21 Downstream rectification block 30 down Ri part

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takeo Araki 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi Inside Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (56) References JP-A-3-75403 (JP, A) JP-A-7-103412 (JP, A) JP-A 62-136709 (JP, U) JP-A 2-109115 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 1/00-1/02 F23C 11/00

Claims (1)

(57) [Claim 1] A fuel distributor for separating finely divided fuel into a rich fuel mixture, a first burner nozzle for guiding and burning a fuel mixture having a high fuel concentration, and a fuel In a combustion burner having a second burner nozzle that guides and burns a fuel mixture having a low concentration, the fuel distributor is constituted by a cyclone-shaped distributor, and an upstream side and a throttle portion of the first burner nozzle are provided in the vicinity thereof. Equivalent angle of each rectification block on the downstream side
A pulverized fuel combustion burner characterized in that four or six rows are provided at a pitch, and the fuel mixture is rectified by combining the rectification blocks.