JP3174638B2 - Premix structure of gas turbine combustor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a premixing structure of a gas turbine combustor for performing Ox combustion, and particularly when a gas fuel such as natural gas (LNG, LPG, etc.) is used, can significantly reduce NOx. This is related to the premixing structure.

[0002]

2. Description of the Related Art Among the conventional low NOx combustors, a technique closest to the present invention will be described. For example, JP-A-61-2212
No. 7 discloses a two-stage combustion system, the first stage employs a multi-nozzle diffusion combustion system, and the second stage employs a multi-nozzle premix combustion system. I have. Then, as a whole, low-temperature combustion is performed by excess air to reduce NOx.

As is well known, gas turbines require extremely wide combustion from ignition to rated load. Therefore, it is not possible to cover this wide combustion range only by premixed combustion having a narrow combustion range. For this reason, from ignition to a certain number of revolutions or a certain load band, it is necessary to rely on a diffusion combustion method having a wide combustion width. However, in the diffusion combustion method, since a high-temperature portion is easily generated locally, the emission level of NOx generated as a result of combustion becomes high. It is necessary to achieve low-temperature combustion. Therefore, at the time of ignition, the start of the gas turbine is started by diffusion combustion, and successive premixing is performed while supporting with a diffusion flame from the point in time when the fluctuation range of the ratio of air and fuel, that is, the air ratio approaches the flammable limit of premix combustion. An operation for switching to combustion is required. This operation enables low NOx operation of the gas turbine.

[0004] On the other hand, in the premixed combustion system, low NOx combustion cannot always be easily achieved.

It is difficult to obtain a completely uniform premixed gas even if the fuel is divided 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 gas. In other words, the meaning of dividing the fuel is to locally supply the fuel in accordance with the air flow rate locally flowing in the vicinity thereof, thereby obtaining a premixed gas as uniform as possible. It is. In particular, in the structure in which fuel is supplied to the premixing passage up, down, left, and right as in the prior art shown here, and the air flow is reversed, the air flow is locally controlled in a three-dimensional and uneven flow space. As a result, it becomes extremely difficult to supply fuel, and as a result, a part having a high gas concentration is generated, and the flame temperature in this part becomes high, thereby promoting the generation of NOx. As described above, in the premixed combustion of low NOx, making the concentration distribution of the premixed gas uniform is a very important basic technique.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to achieve a significant low NOx combustion, thereby obtaining a very uniform premixed gas and enhancing the premixing with air. To make the flame temperature distribution uniform and realize low-temperature combustion, thereby producing thermal N
Gas turbine combustor air that can significantly reduce Ox-
The goal is to provide a fuel premixing structure.

[0007]

According to the present invention, in order to achieve the above object, an annular premixing passage portion is divided radially by a plurality of hollow members or a combination of a partition plate and a hollow member. In addition to reducing the hydraulic diameter and improving the premixing efficiency, a plurality of fuel injection holes are provided on both sides of the hollow member of the premix passage, and fuel is supplied to the hollow portion of this hollow member to locally premix. The fuel is supplied in accordance with the air flow rate, and the mixing is promoted at the reduction portion of the premix passage. This
Here, each fuel injection port of the hollow member locally flows its pitch.
At irregular intervals to match the premixed air volume
To match the amount of premixed air flowing locally through its diameter
It is provided by changing. Therefore, even if the premixing distances are the same, the mixing of air and fuel in the premixing passage can be remarkably improved.

[0008]

In order to improve the mixing of the fuel gas and the premixed air, it is necessary to (1) reduce the hydraulic diameter of the cross section of the premixed passage. (2) reduce the local premixed air flow rate in the premixed passage. (3) A reduction section (mixing promotion) formed by a flow resistor in a premix passage through which a mixture of fuel gas and premix air injected into the premix passage passes. Part) to give a predetermined pressure loss to promote mixing. It is a technical condition to satisfy these three factors. In the present invention, the combination of the hollow member or a hollow member and the partition plate, the hydrodynamic diameter can be reduced, and supplying the fuel gas to the hollow portion of the hollow member, a plurality of the fuel injection ports on both side walls of the hollow member It is provided to supply a fuel corresponding to the local premixed air flow rate flowing through the reduction section, thereby improving the mixing of the fuel gas and the premixed air.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail 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 one-stage premix burner is shown. However, the present invention is not particularly limited, and two or more stages may be included in the present invention without any problem. And The compressed air 1 compressed by the gas turbine compressor (not shown) is diffused.
After the pressure is recovered by the chamber 2, the air is supplied to the air chamber 3.
Part of the compressed air 1 is used as liner-cooling air 4 to cool the liner 21 of the combustor and is supplied into the combustion chamber 12.

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

On the other hand, the premixed fuel 13 is supplied to a common premixed fuel chamber 14, enters the hollow portion 8 of the hollow member 7 from each fuel supply port 16 through the premixed fuel passage 15, The fuel is supplied into the premixing passage 10 from a plurality of fuel injection ports 9 provided on the wall, mixed with the premixed air 5, starts premixed combustion at the premixed burner port 11, and enters the combustion chamber 12. Burn. Further, the diffusion fuel 24 used at the time of ignition of the gas turbine passes through the diffusion fuel passage 25 and the diffusion fuel hole 18.
The fuel is further supplied to the diffusion swirler 19, starts combustion at the diffusion burner port 20, and burns in the combustion chamber 12.

While supporting the combustion with the diffusion flame from the rotation speed of the gas turbine or at a certain partial load, the ratio of the sequential premixed combustion is increased to reach the rated load while lowering the NOx by reducing the ratio. At the time of rated load, the flow rate of the diffusion fuel may be completely zero, or a very small amount of the diffusion fuel may be supplied to stabilize the flame. The high-temperature gas stream 23 burned in the combustion chamber 12 flows through the transition piece 22 and is guided to a turbine inlet (not shown) to drive the gas turbine.

FIG. 2 is a detailed view of the cross section taken along the line AA of FIG. 1, and particularly shows a cross section of the fuel injection port 9 of the hollow member 7. As shown in FIG. The figure shows a specific example in which the annular premix 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 from the plurality of fuel supply ports 16 to the hollow portion 8 of each hollow member 7, and from the plurality of fuel injection ports 9 provided on the side wall of the hollow member 7. It is jetted into the premixed passage narrow portion 29, where it joins with the premixed air 5.

By providing a plurality of hollow members 7 at the entrance of the premix passage 10, the premix passage 10 is narrowed, so that the flow of the premix air 5 is relatively uniform in the radial direction. As shown in FIG. 1, when the premixed air 5 is reversed at the entrance, the drift is not sufficiently corrected, and is affected by the dynamic pressure. As for the annular premix passage as shown in the figure, the premix passage width becomes wider toward the outer diameter side, so that the fuel bias applied in the radial direction can be relatively small with respect to the above-mentioned premixed air drift. But always
Not a uniform flow distribution in the radial direction. Therefore, in order to correct this imbalance, it is necessary to distribute fuel gas corresponding to the amount of air on the fuel side.

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 side surfaces of the hollow member 7
The imbalance of the drift is corrected by changing the pitch. In the second method, as shown in FIG. 5, the diameter of a plurality of fuel injection ports 9 provided on both side surfaces of the hollow member 7 is changed to correct imbalance of the drift.

As shown in FIG. 2, the radial width of the hollow member 7 is changed so that the local flow rate of the premixed air 5 on each section is constant in the radial direction to bias the fuel distribution. A structure that does not hang is also possible.

The position pickled <br/> fuel injection hole 9 for the hollow member 7, be provided in premix passage isthmus 29 to flow after it throttled by the hollow member 7, the flow of the premix passage 10 Since it is not affected by the dynamic pressure, stable fuel supply can be performed. Also, in this cross section, the diffusion air passage 1
7 and the diffusion fuel passage 25 are shown in the center of the figure.

FIG. 3 shows one specific example of the developed view of the BB section in FIG. 1 or the developed view of the CC section in FIG.
As shown, the premixing passage 10 is divided into a plurality of parts by a partition plate 28, and hollow members 7 are provided at the entrances of the respective premixing passages, 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 premixing passage 10 from the fuel injection holes 9 provided on both side walls of the hollow member 7. The wake of the premixed passage narrow portion 29 widens as shown in the figure. Here, the premixed air 5 and the fuel gas are mainly mixed and supplied to the premixed burner port 11. Combustion chamber 12
Combustion takes place within.

FIG. 6 shows another specific example of the developed view of the BB section of FIG. 1 or the developed view of the CC section of FIG. The hollow member 7 functions not only as a mere fuel supply to the premixing passage 10 but also as a kind of partition plate in structure, so that the use of the partition plate 28 shown in FIGS. 2 and 3 is eliminated. I can do it. In this case, the adjacent hollow member 7
As a result, the premix passage narrow portion 31 can be provided as shown. On the downstream side of the hollow member 7, if necessary, a partition plate 30 having an extended rear end 27 of the hollow member 7 is provided as shown in the figure, and a premix burner port is formed as a divided premix passage 10. 11 can be supplied with a premixed gas.

Although not particularly shown, when the pre-mixing passage 10 has a relatively small circumferential imbalance,
It is not necessary to provide the premixing passage narrow portion 31 and can be considered as a modification of the present invention, which is included in the present invention.

FIG. 7 is a view as viewed in the direction D of FIG. 1 and shows the burner opening from inside the combustion chamber 12. The structure shown here is one specific example of the present invention. For example, the premixing burner port 11 may be two-stage or multi-stage, and the diffusion burner port 20 is incorporated in the premixer burner port. These are also included in the present invention. The point is that the invention relates to a structure for obtaining a premixed air / fuel gas mixture having a uniform concentration distribution close to ideal, and can be applied to a combination 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 the premixed air and the fuel gas can be promoted.
A certain degree of pressure recovery can be expected and the hydraulic diameter can be reduced, resulting in a very 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 distribution of fuel in the height direction is supplied in accordance with the premix air flow rate flowing through that portion. This makes it easier to obtain a more uniform premixed gas.

The third effect of the present invention is that, even if the flow is reversed at the intake of the premixed air, for example, the premix passage is restricted by the hollow member, so that the radial drift can be considerably reduced. That is, the velocity distribution at the premix burner opening can be made uniform. Also, by changing the width of the hollow member in the radial direction, uniform distribution of premixed air in the radial direction can be achieved.

The fourth effect of the present invention is to further improve the above-mentioned first to third effects by providing a plurality of hollow members provided on both side surfaces of the hollow member so as to match the local premixed air flow rate. An extremely uniform pre-mixed gas can be obtained by providing a bias to the pitch and the diameter of the fuel nozzle in the fuel nozzle. A fifth effect of the present invention is that a more efficient mixing process can be obtained by combining the above first to fourth effects.

A sixth advantage of the present invention is that low-NOx combustion by premix combustion can be achieved over a wide range of gas turbine load changes by increasing the number of stages of premix burners. As described above, the effects of the present invention are extremely effective in realizing low NOx combustion in a gas turbine.

[Brief description of the drawings]

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

FIG. 2 is a detailed view showing an AA cross section of FIG. 1;

FIG. 3 is a developed view of a BB section of FIG. 1 or a CC section of FIG. 2;

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

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

FIG. 6 is a sectional development view showing another embodiment similar to FIG. 3;

FIG. 7 is a view as viewed in the direction D of FIG. 1, showing a burner opening viewed from the combustion chamber.

[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 portion 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 swirl blade, 2
0: diffusion burner opening, 21: liner, 22: transition piece, 23: high temperature gas flow, 24: diffusion fuel, 25
... diffusion fuel passage, 26 ... premix passage partition, 27 ... rear end of hollow member, 28 ... partition plate, 29 ... premix passage narrow part, 3
0: partition plate, 31: narrow portion of premix passage.

Continued on the front page (72) Inventor Isao Sato 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Shozo Nakamura 502, Kandamachi, Tsuchiura-shi, Ibaraki Machinery, Ltd. (56) References JP-A-2-169828 (JP, A) JP-A-59-101551 (JP, A) JP-A-4-43220 (JP, A) JP-A-63-104816 (JP, U (58) Fields surveyed (Int. Cl. ⁷ , DB name) F23R 3/30 F23R 3/28

Claims (7)

(57) [Claims] 1. A premixing structure of a gas turbine combustor for performing low NOx combustion by premixing a part of combustion air supplied from a compressor as premixed air with fuel, wherein the premixed air is supplied. Premixing passage,
A plurality of radially extending hollow members are provided in the premix passage and divided into a plurality of hollow members. A plurality of fuel injection holes for supplying fuel from the hollow portion of the hollow member to the divided premix passage on both sides of the hollow member. Is established,
A premixing method for a gas turbine combustor, characterized in that the pitches of the fuel injection ports are provided at unequal intervals so as to correspond to the amount of premixed air flowing locally, so as to make the mixing ratio of fuel-air uniform. Construction. 2. A premixing structure of a gas turbine combustor for performing low NOx combustion by premixing a part of combustion air supplied from a compressor as premixed air with fuel, wherein the premixed air is supplied. Premixing passage,
A plurality of radially extending hollow members are provided in the premix passage and divided into a plurality of hollow members. A plurality of fuel injection holes for supplying fuel from the hollow portion of the hollow member to the divided premix passage on both sides of the hollow member. Is established,
A premixing structure for a gas turbine combustor, characterized in that the diameter of each fuel injection port is changed so as to correspond to the amount of premixed air flowing locally, so as to make the fuel-air mixing ratio uniform. 3. A premixing structure of a gas turbine combustor for performing low NOx combustion by premixing a part of combustion air supplied from a compressor as premixed air with fuel, wherein the premixed air is supplied. Premixing passage,
Divided into a plurality of parts by a partition plate extending in the radial direction, and a hollow member extending in the radial direction is provided in each of the divided premixing passages. On both sides of the hollow member, the divided premixing is performed from the hollow portion of the hollow member. A plurality of fuel injection ports for supplying fuel to the passage are provided,
A premixing method for a gas turbine combustor, characterized in that the pitches of the fuel injection ports are provided at unequal intervals so as to correspond to the amount of premixed air flowing locally, so as to make the mixing ratio of fuel-air uniform. Construction. 4. A premixed structure of the gas turbine combustor part of the combustion air to perform low NOx combustion by fuel and premixed as a premixed air supplied from the compressor, the premixed air is supplied Premixing passage,
Divided into a plurality of parts by a partition plate extending in the radial direction, and a hollow member extending in the radial direction is provided in each of the divided premixing passages. On both sides of the hollow member, the divided premixing is performed from the hollow portion of the hollow member. A plurality of fuel injection ports for supplying fuel to the passage are provided,
A premixing structure for a gas turbine combustor, characterized in that the diameter of each fuel injection port is changed so as to correspond to the amount of premixed air flowing locally, so as to make the fuel-air mixing ratio uniform. The tail of claim 5, wherein said hollow member, a gas turbine combustor premixing structure according to claim 1 or 2 characterized by providing a partition plate in the form obtained by extending the tail of the hollow member. 6. The premixing passage according to claim 1, wherein the rear portion of each hollow member is tapered so that each of the divided premixing passages forms a divergent premixing passage, and performs diffusion mixing of premixed fuel and premixed air. Item 6. A premixing structure for a gas turbine combustor according to item 1, 2, 3, 4, or 5. 7. The hollow member according to claim 1, wherein the radial width of the hollow member is changed so that the local premixed air flow rate becomes uniform in the radial direction. Or a premix structure for a gas turbine combustor according to item 6.