JPH0618036A - Premixing chamber for gas turbine combustor - Google Patents

Abstract

PURPOSE:To provide a premixer for a gas turbine burner, which prepares fuel of uniform concentration by means of a simple construction even if it includes bent portinos within it. CONSTITUTION:A space between an inner casing 1 and an outer casing 2 are divided by partition plates 5 into a plurality of small flow passages 6, in which fuel nozzles 7 are provided. After fuel jetted from the fuel nozzles 7 is mixed in the small flow passage 6 with air for combustion flowing from an inlet 3 of a premixing chamber, it reaches an outlet 4 of the premixing chamber. The partition plates 5 are provided with a bent portion 8 and an opening 9 whereby a part of mixed fluid flows out into adjacent small flow passages 6 through the opening 9 to promote mixing of fuel and air for combustion. With this arrangement, uneven distribution of fuel which would otherwise be caused by the influence of drift in the small flow passages 6 is eliminated whereby distribution of fuel concentration is made uniform at the outlet 4 of the premixing chamber. Besides, reduction of NOx generated in a combustion chamber, stabilization of flame, prevention of backfire and reduction of pressure loss are resulted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustor, and more particularly to a premixer for a gas turbine combustor which enables low NOx combustion.

[0002]

2. Description of the Related Art As combustion methods in a gas turbine combustor, there are a diffusion combustion method in which fuel and air are separated and burned, and a premixed combustion method in which fuel and air are premixed and burned. The diffusion combustion method is excellent in flame stability, but NOx in the exhaust gas is high. On the other hand, the premixed combustion method can reduce the generation of NOx in the exhaust gas by lowering the flame temperature. In this premixed combustion system, a premixer is provided in front of the combustion chamber in order to premix fuel and air and supply them to the combustor.

Generally, in a premixer, a flow passage in a double cylinder having an inner cylinder and an outer cylinder is divided into a plurality of small flow passages by a partition plate having no opening, and a fuel nozzle is divided. It is provided in the small channel. The fuel flowing out from the fuel nozzle is mixed with the combustion air in the small flow path, and burns in the combustion chamber connected to the premixer outlet.

Regarding the premixer of the gas turbine combustor,
There are the following two publicly known technology examples. 1. Combustion device and gas turbine device (JP-A-4-103)
916) This known technique prevents combustion vibration by providing a flame holding structure on the outer peripheral portion of the premixed gas jet from the premixer, and provides a flame distribution by providing a flow distributor at the jet end of the premixed gas. It regulates formation and provides low NOx combustion.

2. Gas turbine premixer (JP-A-2-
169828) In this known technique, a plurality of fuel injection nozzles are arranged at intervals in the radial direction, and the fuel injection amount from each nozzle is controlled to make the air flow velocity distribution and the fuel concentration distribution in the radial direction uniform. It is something to do.

[0006]

However, the above-mentioned known technique has the following problems. In the prior art 1, the non-uniformity of the fuel occurs at the outlet of the premixer, which is the inlet of the combustion chamber, due to the non-uniform flow in the flow passage, and the non-uniformity of the fuel causes the non-uniformity of the temperature in the combustion chamber. The generation of NOx increases in the extremely high temperature range. Further, the non-uniformity of the fuel and the non-uniformity of the temperature lower the stability of the flame, which may cause blowout of the flame or flashback of the flame returning from the combustion chamber to the premixer.

In the prior art 2, the fuel injection amount from the nozzle is adjusted to control the air-fuel ratio to improve the non-uniformity of fuel and the non-uniformity of flow velocity. No consideration is given to the non-uniformity of the fuel generated by the drift in the road. Further, it is necessary to provide a plurality of nozzles and a control system for controlling the amount of fuel injected from these nozzles, which complicates the structure.

An object of the present invention is to provide a premixer for a gas turbine combustor, which has a simple structure and can make the fuel concentration distribution at the premixer outlet uniform.

Another object of the present invention is to provide a premixer for a gas turbine combustor that can make the fuel concentration distribution at the outlet of the premixer uniform even if there is a bend in the premixer. is there.

[0010]

To achieve the above object, the present invention provides a double cylinder having an inner cylinder and an outer cylinder,
In a premixer of a gas turbine combustor, which mixes the combustion air and the fuel by injecting fuel into the combustion air flowing in the flow path between the inner cylinder and the outer cylinder, the inner cylinder A partition plate that divides the flow path between the outer cylinder and the outer cylinder in the circumferential direction is provided, and the partition plate has at least one opening.

Preferably, the partition plate has a bent portion, and the opening is provided in the bent portion.

Further preferably, the partition plate has a plurality of openings, and the plurality of openings have different areas.

More preferably, the plurality of openings are
The area becomes smaller toward the downstream side.

Preferably, a porous material is provided in the opening.

Further, according to the present invention, a double cylinder having an inner cylinder and an outer cylinder is formed, and fuel is injected into the combustion air flowing in the flow path between the inner cylinder and the outer cylinder. In a premixer of a gas turbine combustor that mixes the combustion air and the fuel, a partition plate that circumferentially divides a flow path between the inner cylinder and the outer cylinder is provided, and a part of the partition plate. To form an opening.

[0016] Preferably, the partition plate has a bent portion, and a partition plate portion downstream of the bent portion is deleted as a part of the partition plate.

[0017]

In the present invention configured as described above, the partition plate that divides the flow passage between the inner cylinder and the outer cylinder in the circumferential direction has at least one opening, so that the flow through the opening is achieved. The movement of fluid between the passages is enabled and the mixing of fuel and combustion air is promoted.

Further, by providing the opening in the curved portion of the partition plate, uneven distribution of fuel due to uneven flow generated in the curved portion is reduced.

Further, since the plurality of openings of the partition plate have different areas, the movement amount of the fluid between the flow paths is adjusted according to the area of the openings.

Further, since the plurality of openings have smaller areas toward the downstream part, excessive movement of the fluid between the flow paths in the downstream part is prevented.

Furthermore, by providing a porous material in the opening, the strength of the wall surface is ensured and the mixture of the fuel and the combustion air is promoted while preventing the impurities in the mixed fluid from moving between the small flow paths.

Further, according to the present invention, the opening is formed by removing a part of the partition plate which divides the flow passage between the inner cylinder and the outer cylinder in the circumferential direction. Further promote the mixing of. It also reduces the pressure loss due to the wall surface.

Further, by removing a partition plate portion downstream of the bent portion as a part of the partition plate, a rectifying function of the partition plate up to the bent portion is ensured.

[0024]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. A block diagram of the premixer of the gas turbine combustor of this embodiment is shown in FIG. The premixer of the present embodiment is a double cylinder having an inner cylinder 1 and an outer cylinder 2, and forms a flow path from the premixer inlet 3 to the premixer outlet 4. A plurality of partition plates 5 are provided in the space between the inner cylinder 1 and the outer cylinder 2,
The space between the outer cylinder 2 and the outer cylinder 2 is divided into a plurality of small channels 6 by a partition plate 5. A fuel nozzle 7 is provided in each small flow path 6. Further, each partition plate 5 is provided with a bent portion 8 for promoting mixing of the fuel and the combustion air by lengthening the flow path, and the bent portion 8 is provided with a single hole opening 9. Has been.

Of the plurality of small flow paths 6 of the premixer of the gas turbine combustor shown in FIG. 1, two partition plates 5A, 5B,
FIG. 2 shows a structural diagram of a small channel 6A formed by the inner cylinder segment 1A and the outer cylinder segment 2A. Small channel 6A
Forms a flow path from the premixer inlet segment 3A to the premixer outlet segment 4A through the intermediate flow passage 11A downstream thereof. The premixer inlet segment 3A has a shape that is curved in a direction away from the premixer axis line 20, that is, toward the outer periphery. Further, the intermediate flow passage 11A is parallel to the premixer axis line 20, and the premixer outlet segment 4A has a shape twisted toward the front in the drawing. The bent portion 8A is provided with a single hole opening 9A.

In the above structure, the fuel injected from the fuel nozzle 7 is mixed with the combustion air flowing in from the premixer inlet 3 in the small flow passage 6, and then the premixer outlet 4 is mixed.
Reach Further, a part of the mixed fluid flows out to the adjacent small flow path through the opening 9. The present invention eliminates the uneven distribution of the fuel due to the influence of the uneven flow generated in the small flow path 6 due to the outflow flow from the opening 9, and makes the fuel distribution uniform. The operation will be described below.

As a premise of the operation of the present invention, FIG. 3 shows the fuel concentration distribution at the outlet of the premixer in the small flow path using the conventional technique having no opening. The small flow passage 56A in the figure is formed by two partition plates 55A and 55B, an inner cylinder segment 51A, and an outer cylinder segment 52A, and like the small flow passage 6A shown in FIG. 2, the premixer inlet segment 53A. To the premixer outlet segment 54A through the intermediate flow passage 61A downstream thereof. The intermediate flow passage 61A is parallel to the premixer axis 70, and the premixer outlet segment 5
4A has a shape twisted leftward as viewed in the drawing. The figure shows the result of numerical analysis of the fuel concentration distribution at the premixer outlet segment 54A by the three-dimensional advection-diffusion equation. As shown, a fuel concentration distribution from the highest concentration region A to the lowest concentration region E occurs at the premixer outlet. This is due to the uneven distribution of fuel due to the presence of uneven flow in the small flow path.

Next, as a comparative example of the operation of the present invention, FIG. 4 shows a cross-sectional view of two adjacent small flow paths in the case of using the prior art having no opening. Fuel 60 discharged from the fuel nozzle 57
Are carried downstream by the combustion air to the premixer outlet 5
Reach 4. At this time, in the bent portion 58, the high pressure region 61 and the low pressure region 62 are formed on both sides of the partition plate, so that the flow is biased. Due to this uneven flow, the fuel is biased toward the high pressure side of the partition plate, so even if the mixed fluid appears to fill the entire width of the flow path along the line XY in the figure, the inside thereof burns with the fuel as shown in FIG. The high-pressure side reaches the premixer outlet 54 while maintaining a high fuel concentration without being sufficiently mixed with the working air.

On the other hand, FIG. 5 shows a sectional view of two adjacent small flow paths in this embodiment. The cross-sectional structure of the small channel is almost the same as that of FIG. 4 except that the bent portion 8 is provided with the opening 9. In this embodiment, the fuel moves from the high pressure region having a high fuel concentration to the low pressure region having a low fuel concentration through the opening 9. Mixed fluid fills the entire width of the channel Xo-Yo in the figure
The position of the line is not much different from the position of the X-Y line shown in FIG. 4, but the movement of the fuel from the high pressure region to the low pressure region promotes the mixing of the fuel and the combustion air, and thus the inside of the mixed fluid. Thus, the fuel and the combustion air are sufficiently mixed to have a uniform fuel concentration and reach the premixer outlet 54.

Next, FIG. 6 shows the numerical calculation results showing the effect of uniforming the fuel concentration in this embodiment. The figure shows the deviation degree of the fuel by taking the mixing distance on the horizontal axis, and shows three cases where the mobility of the fuel is 0%, 20%, and 40%.
Here, the deviation degree of the fuel indicates the standard deviation of the fuel concentration distribution at the premixer outlet 4, and the mixing distance indicates the distance from the opening 9 to the combustor outlet. Further, the mobility of fuel indicates the rate of movement of fuel from the high-pressure region where the fuel concentration is high to the low-pressure region where the fuel concentration is low, and the mobility of 0% indicates the case of the prior art with no opening. The operating condition range of the present invention is shown in the figure. As shown, in general, the longer the mixing distance and the higher the mobility of the fuel, the smaller the deviation of the fuel.

In the figure, the mobility of the fuel is 2 as compared with the case where the conventional technique is used, that is, the mobility of the fuel is 0%.
In the case of 0%, the deviation degree of the fuel at the premixer outlet 4 is reduced by 30 to 40% when the mixing distance condition represented by the line PQ in the figure is the maximum. Further, when the fuel mobility is 40%, the fuel deviation degree is similarly reduced by 40 to 60%. Here, since the NOx emission amount is proportional to the exponentiation (up to the fourth power) of the deviation degree of the fuel, the NOx emission amount is significantly reduced by this embodiment.

According to this embodiment, since the fluid moves through the opening 9, the mixing of the fuel and the combustion air can be promoted, the uneven distribution of the fuel in the bent portion 8 can be reduced, and the premixer outlet can be reduced. The fuel concentration and flow velocity distribution in 4 can be made uniform. Therefore, it is possible to reduce NOx emissions, stabilize flames, prevent flashback, and reduce pressure loss. Moreover, the same effect can be obtained when the bent portion 8 is not provided.

A second embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a block diagram of the premixer of the gas turbine combustor of this embodiment. In the figure, parts common to those of the premixer in the first embodiment are designated by common numbers. The premixer of this embodiment is substantially the same as the first embodiment except that the partition plate 15 of the bent portion 8 is provided with a plurality of openings 19 having different areas.

According to this embodiment, the number of openings 19 provided in the partition plate 15 and the size of the hole diameter are adjusted to adjust the amount of fuel movement between the small flow paths 6 and 6. You can If the hole diameter is increased or the number of holes is increased to reduce the flow velocity through the opening 19, the pressure loss due to the collision between the flow from the opening 19 and the main flow can be reduced. further,
The openings 19 are distributed and arranged at positions where the high concentration region of the fuel changes, and even when the position where the high concentration region of the fuel collides with the partition plate 5 changes due to the change of the flow of the mixed fluid when the load changes. It is possible to move the fuel between the small channels at the position.

A third embodiment of the present invention will be described with reference to FIG. FIG. 8 shows a block diagram of the premixer of the gas turbine combustor of this embodiment. In the figure, parts common to the premixer in the first and second embodiments are indicated by common numbers. In the premixer of the present embodiment, the plurality of openings 29 having different areas provided on the partition plate 25 of the bent portion 8 have smaller hole diameters toward the downstream side. The other points are almost the same as the second embodiment.

According to this embodiment, since the plurality of openings 29 have smaller areas toward the downstream portion, it is possible to prevent excessive movement of the mixed fluid between the small channels 6 in the downstream portion.

A fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a configuration diagram of the premixer of the gas turbine combustor of the present embodiment. In the figure, parts common to the premixers in the first to third embodiments are indicated by common numbers. In the premixer of this embodiment, the bent portion 1 of the partition plate 35 is used.
A part downstream of 8 is deleted to form an opening, and other points are almost the same as in the third embodiment.

According to the present embodiment, the flow direction is made oblique by the bend portion 18 to keep the mixing distance of the fuel and the combustion air long, and all the part of the partition plate 35 downstream from the bend portion 18 is removed. Therefore, the mixing of the fluid between the small channels 16 can be further promoted. Further, the pressure loss due to the wall surface of the partition plate 35 can be reduced.

A fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 shows a block diagram of the premixer of the gas turbine combustor of this embodiment. In the figure, parts common to the premixers in the first to fourth embodiments are indicated by common numbers. In the premixer of the present embodiment, the porous material 17 such as a wire mesh is attached to the plurality of openings 39 provided in the partition plate 45.

According to this embodiment, it is possible to secure the strength of the wall surface of the partition plate 45 and prevent the movement of impurities in the mixed fluid.

In all of the above embodiments, the small flow path in the premixer has a bent portion, but even if there is no bent portion, a similar effect can be obtained by the mixing promoting action.

[0042]

According to the present invention, since the mixing of the fuel and the combustion air is promoted, the fuel concentration distribution at the premixer outlet can be made uniform and the flow velocity distribution can be made uniform. Therefore, it is possible to reduce the generation of NOx in the combustion chamber, prevent blowout of the flame and backfire, and stabilize the pressure and reduce pressure loss. Moreover, since the partition plate has a simple structure in which only an opening is provided, it is not necessary to provide a plurality of nozzles, a fuel injection control system, and the like, and the manufacturing cost is low. Further, the uneven distribution of the fuel due to the uneven flow generated at the bent portion is reduced, so that the fuel concentration distribution at the outlet of the premixer can be made uniform even when the bent portion exists in the premixer. Furthermore, since the openings of the partition plate have different areas, the amount of movement of the fluid between the flow paths is adjusted according to the area of the openings, and the flow velocity from the openings is reduced to reduce the pressure loss. it can. Further, even when the flow in the premixer changes and the position where it collides with the partition plate changes, the mixing promotion effect can be maintained in response to the change. further,
Since the plurality of openings have smaller areas toward the downstream portion, it is possible to prevent excessive movement of the fluid between the flow paths in the downstream portion. Further, since the porous material is provided in the opening, it is possible to promote the mixing of the fuel and the combustion air while ensuring the strength of the wall surface and preventing the impurities in the mixed fluid from moving between the small flow paths.

Further, in the present invention, the opening is formed by removing a part of the partition plate which divides the flow passage between the inner cylinder and the outer cylinder in the circumferential direction, so that the mixture of the fuel and the combustion air is formed. Can be further promoted. Further, pressure loss due to the wall surface can be reduced. Further, since the partition plate portion downstream of the bend portion is deleted as a part of the partition plate, it is possible to secure the rectifying function of the partition plate portion up to the bend portion and to keep the mixing distance between the fuel and the combustion air long.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a premixer of a gas turbine combustor according to an embodiment of the present invention.

FIG. 2 is a structural diagram of a small flow path in a premixer of a gas turbine combustor.

FIG. 3 is a diagram showing a fuel concentration distribution at a premixer outlet in a small flow path using a conventional technique.

FIG. 4 is a cross-sectional view of two small channels adjacent to a premixer using the prior art.

FIG. 5 is a cross-sectional view of two small flow paths adjacent to each other in the premixer of this embodiment.

FIG. 6 is a diagram showing a numerical calculation result showing the effect of making the fuel concentration uniform.

FIG. 7 is a configuration diagram of a premixer of a gas turbine combustor according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram of a premixer of a gas turbine combustor according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram of a premixer of a gas turbine combustor according to a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram of a premixer of a gas turbine combustor according to a fourth embodiment of the present invention.

[Explanation of symbols]

 5 Partition Plates 5A, 5B Partition Plates 6 Small Flow Paths 6A Small Flow Paths 8 Bent Parts 8A Bent Parts 9 Opening Parts 15 Partition Plates 16 Small Flow Paths 18 Bent Parts 19 Opening Parts 25 Partition Plates 29 Opening Parts 35 Partition Plates 39 Opening Parts 45 partition

Claims (7)

[Claims] 1. A double cylinder having an inner cylinder and an outer cylinder,
A premixer for a gas turbine combustor, which mixes the combustion air and the fuel by injecting fuel into the combustion air flowing in a flow path between the inner cylinder and the outer cylinder, wherein the inner cylinder A premixer for a gas turbine combustor, comprising a partition plate that divides a flow path between the outer cylinder and the outer cylinder in the circumferential direction, and the partition plate has at least one opening. 2. The premixer for a gas turbine combustor according to claim 1, wherein the partition plate has a bent portion, and the opening is provided in the bent portion. Premixer. 3. The gas turbine combustor premixer according to claim 1, wherein the partition plate has a plurality of openings, and the plurality of openings have different areas. Combustor premixer. 4. The premixer for a gas turbine combustor according to claim 3, wherein the plurality of openings have smaller areas toward the downstream part. 5. The premixer for a gas turbine combustor according to claim 1, wherein a porous material is provided in the opening. 6. A double cylinder having an inner cylinder and an outer cylinder,
A premixer for a gas turbine combustor, which mixes the combustion air and the fuel by injecting fuel into the combustion air flowing in a flow path between the inner cylinder and the outer cylinder, wherein the inner cylinder A premixer for a gas turbine combustor, comprising a partition plate that divides a flow path between the outer cylinder and the outer cylinder in the circumferential direction, and forming an opening by deleting a part of the partition plate. . 7. The premixer for a gas turbine combustor according to claim 6, wherein the partition plate has a bent portion, and a partition plate portion downstream of the bent portion is deleted as a part of the partition plate. A premixer for a gas turbine combustor.