JPH06281146A - Burner for combustor - Google Patents

Abstract

PURPOSE:To reduce NOx and the combustion vibration by rapidly promoting the diffusion of a fuel and air by a method wherein a second fuel injection port is arranged on the upstream side of a fuel injection port on the peripheral surface of a nozzle, and a flame holder is arranged on the upstream side of the second fuel injection port. CONSTITUTION:A combustor is equipped with an outer cylinder 11 and cover 12, and is arranged between a turbine casing 10 and compressor casing 26. Also, the combustor is constituted to be a two stage model with a plurality of burners 5A, 7A. In addition. the respective burners 5A, 7A are constituted of respective nozzles 5, 6 and combustion air passages 2, 3. In the meantime, a combustion chamber 1 which is surrounded by a combustion cylinder 4 is formed, and a flame holder 8 is arranged at the exit of the second stage burner 7A. Then, a primary fuel feeding pipe 21 is arranged at the center of the first stage nozzle 5 to divide a secondary fuel feeding passage 22, and at the same time, a first stage fuel 201 which is fed from the secondary fuel feeding passage 22 is fed into a fuel-air stream from a secondary fuel injection port 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a burner for a combustor used in, for example, a gas turbine combustor.
In particular, it relates to an improvement of a burner for a combustor which is formed so that compressed air for combustion flows in the longitudinal direction of the nozzle body.

[0002]

2. Description of the Related Art For example, in order to reduce NOx in the exhaust gas of a gas turbine, a two-stage combustor combining premixed combustion and diffusion combustion has been developed.

This two-stage combustor is disclosed, for example, in US Pat.
898,001, there is a diffusion combustion burner with a fuel nozzle projecting into the combustor upstream of the combustor, and a fuel and air mixture on the downstream outer periphery thereof. There is a premixed combustion burner that supplies gas to the combustion chamber for combustion. In general, all of these burners suppress the amount of NOx generated by making the ratio of fuel and air smaller than the theoretical mixing ratio, that is, by performing lean combustion.

In this case, the degree of NOx generation of the diffusion combustion burner is higher than that of the premixed combustion burner. For this reason, it is even lower NO
In order to achieve x, it is necessary to increase the combustion ratio for premixed combustion (combustion ratio of premixed combustion to total combustion).

In this case, if the capacity of the diffusion combustion burner is decreased and the capacity of the premixed combustion burner is increased, the stability of the premixed combustion burner decreases due to a decrease in the flame holding action of the diffusion combustion burner, and combustion Vibration is likely to occur. Also, during partial load operation, it is basically necessary to keep the fuel-air ratio of the premixture (mixing ratio of fuel and air) constant, so control the amount of air entering the premixer or the number of burners. Switching is taking place.

On the other hand, regarding the flame holding of the premixed flame, it is assumed that a blunt body is arranged in the premixed airflow at the premixing outlet as in the above-mentioned reference, and the flame is stabilized by the vortex formed in the subsequent flow. On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 59-101551, there is known one in which a premixed airflow is formed on the outer peripheral side and a diffusion combustion burner for diffusive combustion is arranged at the center thereof.

In the latter case, the diffusion combustion burner is exclusively operated in the low load operation region, and the diffusion combustion burner is made as small as possible in the high load operation region to exclusively operate the premixed combustion burner.
The generation of Ox is suppressed.

[0008]

The combustion burner thus formed does not cause any particular problem during normal operation, but when the load change is remarkable, the fuel flow rate is narrowed down. Even with a small diffusion combustion, there is a premixed flame corresponding to the load around it, so that combustion oscillation is likely to occur, that is, unstable combustion occurs, and an extremely large amount of NOx is disliked.

The present invention has been made in view of the above, and an object thereof is to provide a combustion burner used in a combustor having a large load fluctuation, which has a wide stable operation range with little combustion oscillation. It is an object of the present invention to provide a combustor burner of this kind capable of reducing NOx.

[0010]

That is, according to the present invention, in a burner for a combustor which is provided with an air flow passage around the nozzle in the longitudinal direction of the nozzle, the compressed air for combustion flows, and A second fuel injection port is provided at a position upstream of the fuel injection port, and a flame stabilizer is provided upstream of the second fuel injection port to achieve the intended purpose. It is a thing.

[0011]

In other words, with this structure, the air vortex that can be formed in the wake of the flame stabilizer rapidly diffuses the fuel injected from the second fuel injection port and the air. No more formation, NO generated in this part
The amount of x becomes small, and further, the combustion gas burned in the downstream of the flame stabilizer mixes and burns in the combustion flame burning downstream of the flame stabilizer, and the combustion becomes stable. Therefore, as a whole, It is possible to obtain this kind of combustor burner which produces little NOx and has a wide stable region.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. The burner for a combustor of the present invention can be used in any one as long as compressed air for combustion flows around the nozzle, but here is an example in the case of being adopted in a gas turbine combustor. Describe.

FIG. 1 shows the combustor of the gas turbine. The combustor is arranged between the turbine casing 10 and the compressor casing 26, and includes a combustor outer cylinder 11 and a combustor outer cylinder cover 12.

The combustor has a first stage burner 5A on the inner peripheral side and a second stage burner 7A on the downstream outer peripheral side.
The first stage burner 5A is composed of the first stage nozzle 5 and the first stage combustion air flow path 2, and the second stage burner 7A is the second stage nozzle 6 and the second stage air. Consists of channel 3,
A combustion chamber 1 surrounded by a combustion cylinder 4 is formed downstream thereof, and a combustor transition piece 9 is connected further downstream thereof, and a high temperature working gas 210 generated in the combustor is supplied to a turbine nozzle 13.

Of the compressed air 100 discharged from the compressor, the first stage combustion air 102 and the second stage combustion air 101.
Burn with the first-stage fuel and the second-stage fuel, respectively. Although not shown in the figure, part of the compressed air flows into the combustor from the wall cooling air of the combustion cylinder and the joint portion of each burner.

The burner 7A of the second stage is provided with a flame stabilizer 8 at the outlet thereof, and the premixed gas 110 'is introduced into the circulation flow formed downstream of the flame stabilizer 8 to perform continuous combustion. .

The burner 5A of the first stage will be described with reference to FIG. The first stage burner 5A is
The first-stage combustion nozzle 5 is attached to the shaft center side of the outer peripheral side cylinder 15 via a plurality of partition plates 14. Partition plate 14
The downstream of the plurality of divided air flow paths formed by the above is opened in the combustor, and the upstream side is a ring-shaped air inlet further upstream from the partition plate. ) 16 is attached, and the vortex generating plate 16 is provided with an air inlet 17 corresponding to each divided air flow path.

A primary fuel supply pipe 21 is attached to the center of the nozzle 5 of the first stage.
The space defined by the nozzle 5 in the stage functions as the secondary fuel supply passage 22 and is supplied from the primary fuel supply pipe 1.
The first-stage fuel 200 is ejected through the primary fuel injection port 23 into the airflow passage near the outlet of the first-stage air passage, and the first-stage fuel 201 supplied from the secondary fuel supply passage is in the air passage. It is supplied into the combustion air flow through a secondary fuel injection port 24 provided near the upstream end of the partition plate. Here, although not shown, the respective fuels 200 and 201 supplied to the primary fuel supply pipe 21 and the secondary fuel supply pipe 22 are supplied from an independent fuel supply system, and the primary fuel is exclusively supplied from the time of starting the gas turbine to the time of light load. During high-load operation of the gas turbine from the fuel supply pipe, fuel is exclusively supplied from the secondary fuel supply pipe for operation.

Further, a spacer ring 18 having a space 19 in the radial direction is attached near the outlet end of the outer peripheral cylinder 15, and the shielding air 103 flows into the combustor through this space 19. The first stage burner is attached to the spacer ring 18 and is attached to the inner peripheral side of the second stage burner via the spring seal 20.

FIGS. 3 and 4 are sectional views taken along the lines A--A and B--B in FIG. 2, respectively.
It is provided so as to correspond to almost the middle of the four. Further, the fuel injection port 23 and the second fuel injection port 24 are provided at approximately the center position of the flow passage defined by the partition plate.

In the first stage burner having such a structure,
The fuel ejected from the primary fuel injection port 23 is supplied into the combustion chamber while being mixed with air in the air flow passage, but is near the outlet of the divided flow passage, and the fuel concentration has a density and stable combustion. Becomes

On the other hand, the fuel injected from the secondary fuel injection port 24 is rapidly mixed with air by the vortex induced by the vortex generation plate 16, and the fuel concentration becomes almost uniform at the outlet and is held in the above-mentioned flame. And burns low NOx.

Further, in the two-stage combustor shown in FIG.
Depending on the combustion conditions, the first-stage flame and the second-stage flame may interfere with each other to cause combustion vibration, or a phenomenon in which the flame becomes unstable. This is mainly due to the fact that the flames interfere with each other in the vicinity of the flame stabilizer that holds the flame. However, with this configuration, although the operation will be described later, these are prevented because the premixed combustion is provided in the vicinity of the diffusion combustion in the vicinity thereof. 1 more
By flowing the shielding air 103 around the outer periphery of the burner at the stage, flame interference in the flame holding portion can be suppressed, and combustion stability is further improved.

FIG. 5 shows another embodiment. Here, a swirler 25, that is, a flame stabilizer for swirling the air to hold a flame, corresponds to each of the flow paths divided in the annular air inlet portion. Is provided. In this case, the swirling flow 102 'promotes the mixing of air and fuel, and the above-mentioned effect can be further improved.

FIG. 6 shows still another embodiment. The same parts as those in FIG. 1 are designated by the same reference numerals, and thus the description thereof will be omitted. In the drawing, the fuel 203 is supplied to the fuel nozzle 5, and is injected into the combustion chamber from the fuel injection port 23 near the tip of the fuel nozzle and burned. A second fuel injection port 24 is provided at a position upstream of the fuel injection port 23 on the peripheral surface of the nozzle body. The second fuel injection port 24 communicates with the fuel hole 24A. The fuel discharged from the fuel hole 24A enters the fuel chamber 24B, passes through the throttle portion 24C and enters the fuel chamber 24D, and the throttle portion 24
It is supplied to the downstream side of the flame stabilizer 16 through E.

The fuel chamber 24B, the throttle portion 24C, the fuel chamber 24D, and the throttle portion 24E are provided in order to make the flow distribution of the fuel in the circumferential direction uniform. For example, many fuel holes 24A are evenly provided in the circumferential direction. If it is provided, the throttle part may be one stage, and if the fuel passage is quite long,
This throttle may be unnecessary.

On the other hand, the combustion air flow 102 is supplied to the combustion chamber. In this case, the combustion air throttle plate 130 is provided upstream of the flame stabilizer.
When the guide plate is provided so that the flow velocity of the combustion air increases around the nozzle, the flow velocity of the flame stabilizer increases and the mixing degree due to the vortex improves, which is effective.

FIG. 7 shows the front of the nozzle, and a plurality of fuel injection holes 23 are provided near the tip of the fuel nozzle. Also, a plurality of narrowed portions are provided around the nozzle. The flame stabilizer 16 is provided on the outer circumference of the passage having the throttle portion.

Although the flame stabilizer has a circular shape in this case, the flame stabilizer does not have to have a circular shape, and may have an elliptical shape, a rectangular shape, or a star shape, for example. The point is that the combustion air flow should be able to hold the flame by generating vortices in the subsequent air flow by the flame stabilizer.

Flame can be maintained even if the angle between the upstream side wall of the flame stabilizer 16 and the combustion air flow is not right, but the right angle is effective in terms of flame holding performance.

FIGS. 8 and 9 show the shape and position of the throttle portion. The throttle portions 24C and 24E are displaced so as to make the circumferential distribution of fuel at the outlet of the fuel passage as uniform as possible. However, the positions, sizes, and shapes of these are of course the same as those of the fuel holes 2.
4A, as well as the volume of the fuel chambers 24B and 24D and the length of the fuel passages, which is an exact determination.

Particularly, it is effective to make the passage area of the passage 24C of the throttle portion smaller than the passage area of the passage 24E of the throttle portion to make the fuel amount in the circumferential direction uniform.

Further, as can be seen from FIG. 8, a fuel hole 24A is provided between the fuel passages 24C in the throttle portion. This is intended to eliminate the influence of the dynamic pressure of the fuel ejected from the fuel holes 24A and to make the distribution of the fuel amount uniform, and there is no reason that this arrangement relationship is always necessary. It should be understood as a relationship.

Next, the flow condition of the ambient air and fuel of the burner of this embodiment will be described with reference to FIG.

First, the fuel 203 is partially supplied upstream, and then injected into the fuel chamber 1 as a fuel jet 23A from a fuel hole 23 provided in the fuel nozzle 5. Along with this, an accompanying flow 23B of the fuel jet is generated. Meanwhile, the combustion air flow 102
Is generated by the ring-shaped flame stabilizer 16 from the edge 16A of the ring as a starting point, and a vortex 102A of the combustion air flow is generated, and a part of the vortex 102A becomes an accompanying flow of the fuel jet. If the fuel hole 23 exists at the position of the flame holding surface 16B of the flame stabilizer 16, the fuel jet 23A
Under the influence of the above, most of the vortex 102A of the combustion air flow is dragged by the fuel jet 23A as the accompanying flow 23B of the fuel jet, and it becomes impossible to form a stable flame on the flame holding surface. That is, it is important that the fuel hole 4 be provided to a certain extent downstream of the flame holding surface 26.

The fuel 205 is also supplied as a fuel flow 206 onto the flame holding surface 16B, and the ring edge 1
Reach 6A. A flame is generated here, and a stable flame can be created by the vortex 102A of the combustion air flow. Therefore, on the flame holding surface 16B, the fuel flow 2
By 06, direct contact with the flame is eliminated, and the heat transfer form is simply heat transfer by radiation.
In order for this fuel flow 206 to flow along the lower surface of the flame stabilizer as shown in the figure, the flow velocity of the fuel flow 206 is due to the vortex 102A of the combustion air flow. Since it is a necessary condition that it is smaller than the swirling flow velocity, it is necessary to carefully set the deceleration of the fuel and the setting of the cross-sectional area of the fuel passage in the throttle portions 24C and 24E described above in order to exert the best performance. However, as a result of the experiment, the fuel 205 is about 2 to 5% of the total amount of the fuel to be supplied, and it will not be a serious problem in the burner design.

[0037]

As described above, according to the present invention, the diffusion of the fuel injected from the second fuel injection port and the air rapidly progresses due to the air vortex which can be formed in the wake of the flame stabilizer. The local high temperature combustion part is no longer formed,
The amount of NOx generated in this part is small, and the combustion gas burned in the downstream of the flame stabilizer is mixed and burned in the combustion flame burning in the downstream side of the flame stabilizer. Therefore, a combustor burner of this kind can be obtained which has a wide stable operation range with little combustion oscillation and can achieve low NOx.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a gas turbine combustor provided with a burner for a combustor of the present invention.

FIG. 2 is a vertical sectional side view showing a combustion burner of the present invention.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a cross-sectional view taken along the line BB of FIG.

FIG. 5 is a vertical sectional side view showing another embodiment of the combustion burner of the present invention.

FIG. 6 is a vertical sectional side view showing still another embodiment of the combustion burner of the present invention.

FIG. 7 is a front view seen from the direction of arrow C in FIG.

8 is a cross-sectional view taken along the line DD of FIG.

9 is a sectional view taken along the line EE of FIG.

FIG. 10 is a vertical cross-sectional side view of the main part of the burner showing the relationship between the fuel flow and the air flow in the combustion burner of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Combustion chamber, 2 ... Air flow path, 5 ... Nozzle, 16 ... Flame stabilizer, 23 ... Fuel injection port, 24 ... Second fuel injection port,

Front page continued (72) Inventor Tamio Inami 502 Jinritsu-cho Machinery Research Center, Tsuchiura-shi, Ibaraki Pref.Hitachi Seisakusho Co., Ltd. (72) Inventor Noriyuki Hayashi 502 Jinta-cho, Tsuchiura-shi Ibaraki Pref. (72) Inventor Hiroshi Inoue, 502 Kintatemachi, Tsuchiura-City, Ibaraki Prefecture, Institute of Mechanical Research, Hiritsu Seisakusho Co., Ltd. (72) Shohei Yoshida, 502, Jinmachi-cho, Tsuchiura, Ibaraki Prefecture, Institute of Mechanical Research, Hitate Co., Ltd. (72) Invention Shigeru Akazu, 502, Jinritsucho, Tsuchiura-shi, Ibaraki, Institute of Mechanical Research, Hiritsu Seisakusho Co., Ltd. (72) Toshifumi Sasao, 502, Jinmachi, Tsuchiura-shi, Ibaraki, Institute of Mechanical Research, Hiritsu, Ltd. (72) Inventor, Shigeru Shodohata, Ibaraki Hachimachi, Hitachi, Ltd. 3-1-1, Hitachi Ltd. Hitachi factory (72) Inventor, Kazuyuki Ito 7-1-1, Omika-cho, Hitachi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) ) Inventor Tadahisa Masai San-cho, Hitachi City, Ibaraki Prefecture Eye No. 2 No. 1 Hitachi Engineering Co., Ltd. in the (72) inventor Isao Sato Hitachi City, Ibaraki Prefecture Saiwaicho Sanchome No. 1 No. 1 stock company Hitachi, Ltd. Hitachi in the factory

Claims (8)

[Claims] 1. A burner for a combustor, comprising: a nozzle having a fuel injection port near a tip on a downstream side; and an air flow path around the nozzle and in which compressed combustion air flows in a longitudinal direction of the nozzle. Combustion characterized in that a second fuel injection port is provided at a position upstream of the fuel injection port on the peripheral surface of the nozzle, and a flame stabilizer is provided upstream of the second fuel injection port. Dexterous burner. 2. A combustor burner in which diffusion combustion is performed, comprising a nozzle having a fuel injection port near a downstream end and an air flow passage around which the compressed combustion air flows, Combustion characterized in that a second fuel injection port is provided at a position upstream of the fuel injection port on the peripheral surface, and the fuel injected from the second fuel injection port is premixed and burned. Dexterous burner. 3. The burner for a combustor according to claim 2, wherein the fuel injection port and the second fuel injection port are each provided with an independent fuel supply device. 4. A burner burner, comprising: a nozzle having a fuel injection port near a downstream end thereof; and an air flow path around the nozzle and in which compressed combustion air flows in the longitudinal direction of the nozzle. A second fuel injection port is provided at a position upstream of the fuel injection port on the peripheral surface of the nozzle, and a flame stabilizer is provided upstream of the second fuel injection port and the second fuel injection is provided. A burner for a combustor, characterized in that fuel injected from a mouth is formed along a surface of the flame stabilizer on the combustion chamber side. 5. A burner for a combustor, comprising: a nozzle having a fuel injection port near a downstream end thereof; and an air passage around the nozzle and in which combustion air flows in the longitudinal direction of the nozzle, wherein the nozzle is a nozzle. A second fuel injection port is provided at a position upstream of the fuel injection port on the circumferential surface of, and a flame stabilizer is provided upstream of the second fuel injection port, and the flame stabilizer is provided upstream of the flame stabilizer. A burner for a combustor, characterized in that a throttle portion for narrowing combustion air is provided on the side. 6. A burner for a combustor, comprising: a nozzle having a fuel injection port near a downstream end thereof; and an air flow path around the nozzle and in which combustion air flows in a longitudinal direction of the nozzle. A second fuel injection port is provided at a position upstream of the fuel injection port on the circumferential surface of, and a flame stabilizer is provided upstream of the second fuel injection port, and the flame stabilizer is provided upstream of the flame stabilizer. A burner for a combustor, characterized in that a guide for guiding combustion air to flow along the nozzle surface is provided on the side. 7. A burner for a combustor, comprising: a nozzle having a fuel injection port near a downstream end thereof; and an air flow path around the nozzle and in which combustion air flows in a longitudinal direction of the nozzle, wherein the nozzle is a nozzle. A fuel supply part having an injection port that is open upstream of the fuel injection port, a throttle part is provided in the fuel flow passage of the second fuel supply part, and the second fuel supply part A burner for a combustor, characterized in that a flame stabilizer is provided on the upstream side of the injection port. 8. The burner for a combustor according to claim 7, wherein the fuel supplied to the fuel injection port and the second fuel injection port is a gas fuel.