JPH06101840A - Premixing structure for gas turbine combustor - Google Patents

Abstract

PURPOSE:To provide an effective premixing structure being fundamental arts through which premixture air and fuel are uniformly mixed together when premixed combustion is executed to suppress the production of NOx owing to a gas turbine combustor. CONSTITUTION:At a premixing burner 11 port arranged in a single stage or a multistage, an annular premixing passage 10 at each stage is divided into a plurality of sections by means of a hollow member 7 or the hollow member 7 and a partition plate to reduce a hydraulic diameter, and a plurality of fuel gas injection nozzles are arranged on both sides of the hollow member 7. Fuel is fed to a hollow part 8 of a hollow member to feed fuel responding to a local premixed air flow rate of the divided premixing passage 10, and mixture is promoted by the reduction part of the premixing passage 10 formed of a hollow member 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a low N by premixed combustion.
A gas turbine combustor capable of significantly reducing NOx, particularly when a gaseous fuel such as natural gas (LNG, LPG, etc.) is used, relating to a premixing structure of a gas turbine combustor for performing Ox combustion. Of the premixed structure of.

[0002]

2. Description of the Related Art Among conventional low NOx combustors, a technique closest to the present invention will be described. For example, JP-A-61-2212
In the contents disclosed in the publication of No. 7, the two-stage combustion system is adopted, the first stage adopts the multi-nozzle diffusion combustion system, and the second stage adopts the multi-nozzle premix combustion system. There is. As a whole, low temperature combustion is performed due to excess air to reduce NOx.

As is well known, a gas turbine requires an extremely wide range of combustion from ignition to rated load. Therefore, it is impossible to cover this wide range of combustion only by premixed combustion with a narrow combustion range. Therefore, from ignition to a certain number of revolutions or a certain load band, there is no choice but to rely on a diffusion combustion system with a wide combustion width. However, in the diffusion combustion method, since a high temperature part is likely to be generated locally, the NOx emission level generated as a result of combustion becomes high. Therefore, in order to achieve low NOx, switch to premixed combustion with excess air and make it uniform. It is necessary to achieve low temperature combustion. Therefore, at the time of ignition, the gas turbine starts to be started by diffusion combustion, and when the fluctuation range of the air-fuel ratio, that is, the air ratio approaches the flammability limit of premixed combustion, it is sequentially premixed while being supported by the diffusion flame. An operation to switch to combustion is required. This operation enables low NOx operation of the gas turbine.

On the other hand, if the premixed combustion method is used, it is not always possible to easily achieve low NOx combustion.

It is difficult to obtain a completely uniform premixed gas even if the fuel is subdivided and supplied to a simple premixing passage having a short mixing distance as shown in FIGS. In particular, there is a certain concentration distribution in the premixed air. In other words, the only purpose of subdividing the fuel is to locally supply the fuel corresponding to the flow rate of the air that flows in the vicinity of the fuel, and as a result, it is possible to obtain a premixed mixture that is as uniform as possible. It is a thing. In particular, in the structure in which the fuel is supplied vertically and horizontally to the premixing passage and the air flow is reversed as in the prior art shown here, the air flow rate is locally corresponded to a three-dimensional and biased space. As a result, it becomes extremely difficult to supply the fuel, and as a result, a portion having a high gas concentration is partially generated, the flame temperature becomes high in this portion, and NOx generation is promoted. Thus, in the low NOx premixed combustion, making the concentration distribution of the premixed gas uniform is an extremely important basic technique.

[0006]

The object of the present invention is to achieve a significantly lower NOx combustion, for which purpose a very homogeneous premix is obtained and the premixing with air is enhanced. Makes the flame temperature distribution uniform and realizes low temperature combustion.
Air in a gas turbine combustor that can significantly reduce Ox-
It is to provide a premixed structure for fuel.

[0007]

In the present invention, in order to achieve the above-mentioned object, the annular premixing passage portion is radially divided by a plurality of hollow members or a combination of partition plates and hollow members. In addition to reducing the hydraulic diameter to improve the premixing efficiency, multiple fuel injection holes are provided on both sides of the hollow member of the premixing passage, and fuel is supplied to the hollow part of this hollow member to premix locally. Fuel corresponding to the air flow rate is supplied to promote mixing in the deceleration portion of the premix passage. Therefore, even if the premixing distance is the same, the air-fuel mixing in the premixing passage can be dramatically improved.

[0008]

In order to improve the mixing of fuel gas and premixed air, (1) reduce the hydraulic diameter of the cross section of the premixing passage. (2) reduce the local premixing air flow rate in the premixing passage. Supplying the appropriate fuel gas (3) The speed reducer (mixing promotion) constituted by the flow resistor is provided in the premixing passage through which the mixture of the fuel gas and the premixing air injected in the premixing passage passes. Part), and it is a technical condition to satisfy these three elements for promoting a mixing by giving a predetermined pressure loss. In the present invention, a hollow member or a combination of a hollow member and a partition plate reduces the hydraulic diameter, supplies fuel gas to the hollow portion of the hollow member, and provides a plurality of fuel injection holes on both side walls of the hollow member. The fuel is supplied in proportion to the local flow rate of the premixed air flowing through the speed reducer, thereby improving the mixing of the fuel gas and the premixed air.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 shows a gas turbine combustor 1 according to the present invention.
It is sectional drawing which shows a specific example. In this specific example, an example of a single-stage premix burner is shown, but the present invention is not particularly limited, and two or more stages may be included in the present invention without any problem. And Compressed air 1 compressed by a gas turbine compressor (not shown) is diffused.
After the pressure is recovered by the z, it is supplied to the air chamber 3.
A portion of the compressed air 1 is used as liner cooling air 4 to cool the combustor liner-21 and is fed into the combustion chamber 12.

The other part of the compressed air 1 is supplied to the premix passage 10 as the premix air 5 and is supplied to the combustion chamber 12 as the premix gas from the premix burner port 11. The remaining compressed air 1 passes through the diffusion air passage 17 as diffusion air 6 and is supplied to the combustion chamber 12 from the diffusion burner port 20 via the diffusion swirl vanes 19.

On the other hand, the premixed fuel 13 is supplied to the common premixed fuel chamber 14, passes through the premixed fuel passage 15 and enters the hollow portion 8 of the hollow member 7 from each fuel supply port 16, and both sides of the hollow member 7 are fed. It is supplied into the premix passage 10 from a plurality of fuel injection holes 9 provided on the wall, is mixed with the premix air 5, and starts premix combustion at the premix burner port 11 into the combustion chamber 12. To burn. The diffusion fuel 24 used at the time of ignition of the gas turbine passes through the diffusion fuel passage 25 and passes through the diffusion fuel hole 18
It is further supplied into the diffusion swirl vane 19, starts burning at the diffusion burner port 20, and burns inside the combustion chamber 12.

While the combustion is supported by the diffusion flame from the rotational speed of the gas turbine or at a certain partial load, the ratio of the successive premixed combustion is increased to achieve the NOx reduction while attaining the rated load. At the rated load, the diffusion fuel flow rate may be set to zero, or a very small amount of diffusion fuel may be supplied to stabilize the flame. The high-temperature gas stream 23 burned in the combustion chamber 12 flows in the transition piece 22 and is guided to the turbine inlet (not shown) to drive the gas turbine.

FIG. 2 is a detailed view of the AA cross section of FIG. 1, and particularly shows a cross section of the fuel injection port 9 of the hollow member 7. The drawing shows a specific example in which the annular premixing passage 10 is equally divided by 16 hollow members 7 provided in the radial direction, but the number of divisions is not particularly limited. The fuel gas supplied to the premixed fuel passage 15 is distributed to the hollow portion 8 of each hollow member 7 from each of the plurality of fuel supply ports 16 and from the plurality of fuel injection ports 9 provided on the side wall of the hollow member 7. It is ejected to the narrow portion 29 of the premix passage, and merges there with the premix air 5.

By providing a plurality of hollow members 7 at the inlet of the premix passage 10, the premix passage 10 is throttled, so that the flow of the premix air 5 is relatively uniform in the radial direction. If the premixed air 5 is reversed at the inlet as shown in FIG. 1, the drift will not be corrected sufficiently and will be affected by the dynamic pressure. With respect to the annular premixing passage as shown in the drawing, the width of the premixing passage becomes wider toward the outer diameter side, so that the bias of the fuel given in the radial direction can be relatively small against the above-mentioned premixed air drift. However, it is not always possible to have a uniform flow distribution in the radial direction. Therefore, in order to correct this imbalance, it is necessary to distribute the fuel gas on the fuel side in proportion to the amount of air.

In the present invention, this imbalance is corrected by two methods. The first method is as shown in FIG.
A plurality of fuel injection holes 9 provided on both sides of the hollow member 7.
The imbalance of the drift is corrected by changing the pitch of. As shown in FIG. 5, the second method is to correct the unbalance of the drift by changing the nozzle diameters of the plurality of fuel nozzles 9 provided on both side surfaces of the hollow member 7.

Further, as shown in FIG. 2, the width of the hollow member 7 in the radial direction is changed to make the flow rate of the local premixed air 5 on each cross section constant in the radial direction to bias the fuel distribution. It is also possible to have a structure that does not hang.

The position of the fuel injection port 9 with respect to the hollow member 7 should be provided in the narrow portion 29 of the premixing passage narrowed by the hollow member 7 or in the downstream thereof to reduce the dynamic pressure of the flow in the premixing passage 10. Since it is not affected, stable fuel supply can be performed. Also, in this cross section, the diffusion air passage 1
7 and diffusion fuel passage 25 are shown in the center of the figure.

FIG. 3 shows one specific example of the BB sectional development view of FIG. 1 or the CC sectional development view of FIG.
As shown in the figure, the premixing passage 10 is divided into a plurality of parts by a partition plate 28, and a hollow member 7 is provided at the inlet of each premixing passage, and the premixing passage narrow portions 2 are provided on both sides thereof.
9 are configured. The fuel supplied to the hollow portion 8 of the hollow member ejects the fuel into the premix passage 10 from the fuel injection ports 9 provided on both side walls of the hollow member 7. Then, the wake of the narrow portion 29 of the premixing passage widens toward the end as shown in the drawing, where the premixing air 5 and the fuel gas are mainly mixed and supplied to the premixing burner port 11. Combustion chamber 12
Combustion takes place inside.

FIG. 6 shows another specific example of the BB sectional development view of FIG. 1 or the CC sectional development view of FIG. The hollow member 7 not only serves as a fuel supply to the premix passage 10, but also functions as a partition plate of one kind structurally, and the use of the partition plate 28 shown in FIGS. 2 and 3 is eliminated. You can In this case, the adjacent hollow members 7
Thus, the premixing passage narrow portion 31 can be provided as illustrated. On the downstream side of the hollow member 7, if necessary, a partition plate 30 in which the rear end 27 of the hollow member 7 is extended is provided as shown in the drawing, and the divided premix passage 10 serves as a premix burner port. Premixture 11 can be supplied.

Although not shown in the drawing, when the circumferential unbalance of the premix passage 10 is relatively small,
The premixing passage narrow portion 31 may not be provided and can be considered as a modification of the present invention, and is included in the present invention.

FIG. 7 is a view as viewed from D of FIG. 1, and shows the burner port as seen from the inside of the combustion chamber 12. The structure shown here is one specific example of the present invention. For example, the premixing burner port 11 may have two stages or multiple stages, and the diffusion burner port 20 is incorporated in the premixing burner port. Those are also included in the present invention. In short, the invention relates to a structure for obtaining a uniform concentration distribution of premixed air and fuel gas that is close to ideal, and can be developed into a combined structure of several burners as described above. Diffusion fuel passage 2 in the center
5 is indicated by a broken line.

[0022]

The first effect of the present invention is that by providing a plurality of hollow members and partition plates in the annular premixing passage, the mixing of premixed air and fuel gas can be promoted, and
A certain degree of pressure recovery can be expected and the hydraulic diameter can be reduced, resulting in extremely efficient mixing. A second effect of the present invention is that a hollow member is provided in the height direction (radial direction) of the annular premix passage, and the fuel distribution in the height direction is supplied corresponding to the premix air flow rate flowing therethrough. This makes it easier to obtain a more uniform premixed gas.

A third effect of the present invention is that even if the structure is such that the flow is reversed at the intake of premixed air, since the premixing passage is throttled by the hollow member, radial uneven flow is considerably reduced. That is, it can be corrected and the velocity distribution at the premix burner port can be made uniform. Further, by changing the width of the hollow member in the radial direction, uniform premixed air distribution in the radial direction can be achieved.

A fourth effect of the present invention is, in order to further improve the third effect over the first effect, to provide a plurality of plural members provided on both side surfaces of the hollow member so as to correspond to the local premixed air flow rate. It is possible to obtain an extremely uniform premixed gas by biasing the nozzle pitch and the nozzle diameter in the fuel nozzles. The fifth effect of the present invention is that a more efficient mixing process can be obtained by combining the above first to fourth effects.

The sixth effect of the present invention is that by making the premixing burner port multistage, low NOx combustion by premixing combustion can be achieved over a wide range of load changes of the gas turbine. As described above, the effects of the present invention are extremely effective in achieving low NOx combustion in a gas turbine.

[Brief description of drawings]

FIG. 1 is a sectional view showing a specific example of a gas turbine in which premixed combustion and diffusion combustion are combined according to the present invention.

FIG. 2 is a detailed view showing an AA cross section of FIG.

FIG. 3 is a development view of the BB cross section of FIG. 1 or the CC cross section of FIG.

FIG. 4 is a partial perspective view showing an example in which a bias is provided at a fuel injection port.

FIG. 5 is a partial perspective view showing an example in which a bias is provided at a fuel injection port.

6 is a sectional development view showing another embodiment similar to FIG.

7 is a view showing a burner port as viewed from the inside of the combustion chamber, as shown in the view D of FIG. 1. FIG.

[Explanation of symbols]

1 ... Compressed air, 2 ... Diffuser, 3 ... Air chamber, 4 ... Liner-cooling air, 5 ... Premixed air, 6 ... Diffusion air, 7 ...
Hollow member, 8 ... Hollow part of hollow member, 9 ... Premix fuel injection port, 10 ... Premix passage, 11 ... Premix burner port, 12 ...
Combustion chamber, 13 ... Premixed fuel, 14 ... Premixed fuel chamber, 15
... premixed fuel passage, 16 ... premixed fuel supply port, 17 ... diffusion air passage, 18 ... diffusion fuel hole, 19 ... diffusion swirler, 2
0 ... diffusion burner port, 21 ... liner, 22 ... transition piece, 23 ... hot gas flow, 24 ... diffusion fuel, 25
... diffusion fuel passage, 26 ... premixing passage partition part, 27 ... hollow member rear part, 28 ... partition plate, 29 ... premixing passage narrow part, 3
0 ... partition plate, 31 ... narrow part of premix passage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Sato 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Shozo Nakamura 502 Jinmachi, Tsuchiura-shi, Ibaraki Stock Company Hiritsu Seisakusho Mechanical Research Center

Claims (7)

[Claims] 1. A gas turbine combustor for performing a low NOx combustion by premixing a part of combustion air supplied from a compressor as a premixed air with a fuel to provide a plurality of radii in an annular premixing passage. A hollow member extending in the direction is provided, the annular premixing passage is divided into a plurality of parts by the hollow member, and a plurality of fuel injection ports are provided on both sides of each hollow member to supply fuel to the hollow part of each hollow member. However, the hollow member promotes the mixing of the fuel supplied from the fuel injection port and the premixed air supplied to each of the divided premixing passages to perform the low NOx combustion, and the preheating of the gas turbine combustor is characterized. Mixed structure. 2. In a gas turbine combustor for premixing a part of combustion air supplied from a compressor with fuel as premixed air to perform low NOx combustion, an annular premixing passage extends in a radial direction. It is divided into a plurality of parts by a partition plate, a hollow member extending in the radial direction is provided in each of the divided premix passages, a plurality of fuel injection holes are provided on both sides of the hollow member, and fuel is supplied to the hollow part of each hollow member. However, the hollow member promotes the mixing of the fuel supplied from the fuel injection port and the premixed air supplied to each of the divided premixing passages to perform the low NOx combustion, and the preheating of the gas turbine combustor is characterized. Mixed structure. 3. The divided premixing passage is widened toward the end by forming the rear portion of the hollow member into a tapered shape so that the premixed fuel and the premixed air are diffused and mixed. Alternatively, the premixing structure of the gas turbine combustor according to Item 2. 4. The fuel-air mixing ratio is made uniform by arranging a plurality of fuel injection port pitches provided on both sides of the hollow member at unequal intervals so as to correspond to the locally mixed premixed air amount. The premixing structure of the gas turbine combustor according to claim 1 or 2, characterized in that. 5. The fuel-air mixing ratio is made uniform by changing the diameters of a plurality of fuel injection holes provided on both sides of the hollow member so as to correspond to the locally mixed premixed air amount. The premixing structure of the gas turbine combustor according to claim 1 or 2. 6. The premixing structure for a gas turbine combustor according to claim 1 or 2, wherein the radial width of the hollow member is changed so that the local air flow rate becomes uniform in the radial direction. A premixing structure for a gas turbine combustor, characterized in that the NOx fuel is promoted by promoting the mixing of the fuel and the fuel. 7. The premixing structure for a gas terpin fuel unit according to claim 1 or 3, wherein a partition plate having a shape in which the rear part of the hollow member is extended is provided at the rear part of the hollow member, and the premixed air and the fuel are mixed together. A premixing structure for a gas turbine combustor characterized by promoting low NOx combustion by promoting mixing.