JP2523500B2 - Gas turbine combustor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a catalytic combustion type gas turbine combustor, and more particularly to a gas turbine combustor operable in a wide load range.

[Technical Background of the Invention and Problems Thereof] In recent years, with the depletion of petroleum resources and the like, various alternative energies have been demanded, and on the other hand, efficient use of energy resources has been demanded. Among those that meet these requirements, a combined cycle power generation system that combines a gas turbine that uses natural gas as a fuel and a steam turbine is being studied. This combined power generation system has higher power generation efficiency than the conventional steam turbine power generation system that uses fossil fuels. Therefore, it is possible to effectively convert natural gas fuel, whose production is expected to increase in the future. Is expected as. A gas turbine combustor used in a gas turbine power generation system ignites a mixture of fuel and air using a spark plug or the like to perform homogeneous combustion. An example of such a combustor is shown in FIG. 2. In the combustor 1, the fuel injected from the fuel supply port, that is, the fuel nozzle 3 into the combustion pipe 2 is introduced from the air inlet 2a for combustion. It is mixed with air 5, ignited by the spark plug 4 and burned. Then, the burned gas is further added with cooling air 6 and dilution air 7, cooled and diluted to a predetermined turbine inlet, and then injected from the outlet end 8 into the gas turbine. One of the serious problems in such a conventional combustor is that a large amount of nitrogen oxide (NOx) gas is produced during combustion of fuel.

The reason why this NO _x gas is generated is that there is a high temperature portion during the combustion of the fuel. NOx is usually produced by the reaction of nitrogen and oxygen in the combustion air with the following equation when no nitrogen component is present in the fuel.

N ₂ + O ₂ 2NO (1) The higher the temperature of the above reaction, the more it shifts to the right and the amount of nitric oxide (NO) produced increases. Part of NO is further oxidized to produce nitrogen dioxide (NO ₂ ).

FIG. 3 shows a temperature distribution in a fluid flow direction in a conventional gas turbine combustor. As shown in the figure, the temperature distribution in the combustor has a maximum value, and after reaching the maximum temperature, it is cooled to a predetermined turbine inlet temperature by cooling and dilution air. Since the maximum temperature in the combustor can reach 2000 ° C, the amount of NOx produced sharply increases near this shaded area. As described above, the conventional gas turbine combustor has a problem that a large amount of NOx is produced due to the presence of a high temperature part in part, and therefore, a flue gas denitration device or the like must be provided.
There was also a problem that the device became complicated.

In order to solve such a problem of the gas turbine combustor, a two-stage combustion system in which combustion air is introduced in two stages and fuel is combusted is being studied. However, this method requires careful attention to the adjustment of the amount of air to be introduced in order to introduce air in two stages, the temperature inside the combustor is relatively high, and the effect of reducing the amount of NOx is not sufficient.

In view of the above, a heterogeneous combustion method using a solid-phase catalyst (hereinafter referred to as a catalyst combustion method) has been recently proposed, as opposed to the above-mentioned method using a homogeneous reaction only in the gas phase.

The catalytic combustion method uses a catalyst to burn a mixture of fuel and air.This method allows combustion to be started even with relatively low-concentration fuel, thus lowering the maximum temperature during combustion. No cooling air is required, or the required amount can be reduced. In this way, the effect of lowering the maximum temperature and the amount of NOx generated can be extremely reduced. Further, the turbine inlet temperature is the same as the conventional one, and the fuel can be completely burned.

FIG. 4 shows an example of such a catalytic combustion type combustor, in which a part of the fuel injected from the fuel nozzle 3 is mixed with the combustion air 5 and ignited and burned by the spark plug 4 to be a preheating source. I am trying. The remaining fuel is injected from another fuel nozzle 3a, mixed with the combustion air 5, and nonuniform in the combustion catalyst 9 formed by coating the noble metal-based catalyst on the flow path of the honeycomb structure formed of ceramic or the like. System combustion progresses.

FIG. 5 shows the temperature distribution in the combustor. In the figure, curve a is based on the conventional normal combustion system shown in FIG. 2, curve b is based on the two-stage combustion system, and curve c is based on the catalytic combustion system. As is clear from the figure, the catalytic combustion method is preferable because it has the lowest maximum temperature.

However, such a catalytic combustion type gas turbine combustor has the following problems. That is, since the catalyst installed in the combustor is designed for certain optimum conditions such as the flow velocity and the fuel concentration, it is difficult to maintain a stable operating state over the entire load. Specifically, the catalyst temperature rises under the condition that the flow velocity is slower than the catalyst design condition or the fuel concentration is high, and in extreme cases, the catalyst may be deteriorated or damaged. On the other hand, conversely, under the condition that the flow velocity is high or the fuel concentration is low, there is a disadvantage that catalytic combustion does not occur.

[Object of the Invention] An object of the present invention is to solve the problems of the prior art and to provide a catalytic combustion type gas turbine combustor capable of stable operation over a wide range of loads.

[Summary of the Invention] In order to achieve the above object, the present inventors have conducted intensive studies focusing on the structure of a combustor, particularly the structure of a combustion tube. Although the area is narrow, we focus on the premixed combustion method that has the advantage of being able to suppress the production of nitrogen oxides, and by combining this premixed combustion method with a normal catalytic combustion method, the load fluctuation including the start time The present invention has been completed by finding that it is possible to keep the load on the catalyst constant if the premixed combustion is used.

That is, the gas turbine combustor of the present invention has a catalyst combustion chamber having an air inlet and a fuel supply port, and a downstream end of the catalyst combustion chamber, which communicates with the catalyst combustion chamber and has an air inlet and a fuel supply port. It is characterized in that it is provided with a combustion tube in which the mixed combustion chamber is arranged independently of each other.

Hereinafter, the gas turbine combustor of the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing an example of the basic structure of a gas turbine combustor of the present invention, in which the same components as those in FIGS. 2 and 4 are designated by the same reference numerals. First, in the gas turbine combustor 11 of the present invention, the combustion pipe 2 is a catalytic combustion chamber.
2b and a premix combustion chamber 2d. The premixed combustion chamber 2d is arranged around the catalyst 9 filled in the vicinity of the downstream end of the catalyst combustion chamber 2b (in the drawing, in an annular shape), and has an air inlet 2c and a fuel supply port, that is, a fuel. nozzle
It has 3b and a spark plug 10. The premixed combustion chamber 2d communicates with the combustion chamber 2b at the downstream end 2e of the catalytic combustion chamber 2b.

In such a combustor 11, the premix combustion chamber 2d may be independent of the catalyst combustion chamber 2b, and is not limited to the structure in which it is annularly arranged around the catalyst combustion chamber 2b as shown in FIG. Absent. That is, for example, contrary to the above, one in which the catalytic combustion chamber is annularly arranged around the premixing combustion chamber, or a partition wall is provided in the longitudinal direction of the combustion tube to divide the catalyst tube into two parts, one of which is the premixing combustion chamber, The other may be a catalytic combustion chamber. Further, the volume ratio of the catalytic combustion chamber 2b and the premixed combustion chamber 2d is preferably set appropriately depending on the activity of the catalyst, the type of fuel, the required combustion gas temperature, etc. The ratio of the flow passage cross-sectional area with the mixed combustion chamber 2d is 6:
It is preferably about 5 to 9: 1. Further, if the flow passage 2f in the communication portion 2e of the combustion tube 2 is expanded in diameter, the combustion vortex generated in the expanded flow passage 2f during premix combustion improves the flame holding effect and stabilizes the premix combustion. The advantage is that

In the gas turbine combustor 11 having such a structure, at the time of starting, fuel is first supplied from the fuel nozzle 3b to the premix combustion chamber 2d, and the spark plug 10 causes premix combustion. Next, fuel is supplied from the fuel nozzle 3 into the catalytic combustion chamber 2b, the gas temperature is raised to a temperature at which the spark plug 4 ignites and catalytic combustion starts, and further, fuel for catalytic combustion is supplied from the fuel nozzle 3a. Combustion by the catalyst 9 is caused. At this time, in the conventional combustor, there is a problem that the unburned gas that has passed through the catalyst is directly discharged into the atmosphere. However, in the combustor of the present invention, the inconvenience as in the prior art is eliminated because the heat source during the premixed combustion completely burns the catalyst 9 immediately after passing through it.

Further, after the catalytic combustion is started, it is possible to stabilize the catalytic combustion by always fixing the fuel supply amount from the fuel nozzles 3 and 3a of the catalytic combustion chamber 2b to an optimum value regardless of the load fluctuation of the combustor. It is preferable to maintain the temperature at a low level and to extend the life of the catalyst. Then, the load fluctuation is offset by changing the fuel supply amount from the fuel nozzle 3b of the premix combustion chamber 2d, so that the load on the catalyst is always kept constant. Specifically, in the combustor 11, under the condition that the flow velocity is slower or the fuel concentration is higher than the design condition of the catalyst 9, the fuel supply amount from the fuel nozzle 3b is kept low to prevent the catalyst from being deteriorated due to the temperature rise. Conversely, under the condition that the flow velocity becomes fast or the fuel concentration becomes low, the fuel supply amount from the fuel nozzle 3b is increased to prevent the catalyst temperature from decreasing.

In such premixed combustion, the combustion temperature was 1600
When the temperature exceeds ° C, NOx is rapidly generated. Therefore, it is preferable to determine the maximum fuel supply amount from the fuel nozzle 3b in consideration of this. Further, by making the air inlet 2c of the premix combustion chamber 2d a structure in which the amount of air can be controlled, it is possible to further expand the load region where stable combustion of the combustor is possible.

Embodiment of the Invention A gas turbine combustor 11 having an annular premixed combustion chamber 2d as shown in FIG. 1 was manufactured. The volume ratio between the catalytic combustion chamber 2b inside the combustion tube 2 and the premixed combustion chamber 2d outside was set to 3: 2 in terms of the cross-sectional area of each flow passage. Further, the combustion pipe 2 is formed with the expanded diameter portion 2f in the communication portion 2e, and the radius thereof is expanded by 50%. The catalyst 9 has a diameter of 10
A noble metal catalyst having a diameter of 0 mm and a length of 120 mm was used. Further, methane gas was used as the fuel, the temperature of the fuel / air mixed gas supplied to the catalyst 9 was 450 ° C., and the flow velocity was 20 m / sec.

In such a gas turbine combustor 11, first, at the time of starting, the adiabatic flame temperature is passed from the fuel nozzle 3b to the premix combustion chamber 2d.
Fuel of 1300 ° C. was supplied, and spark plug 10 was ignited for premixed combustion. Then, fuel was supplied from the fuel nozzle 3 into the catalytic combustion chamber 2b and ignited by the spark plug 4 to raise the gas temperature to 450 ° C. Subsequently, the fuel was supplied from the fuel nozzle 3a so that the adiabatic flame temperature became 1000 ° C. In this state, the maximum temperature of the catalyst 9 is 900 ° C,
It was confirmed that the unburned gas in the catalytic combustion chamber 2b is discharged through the catalyst 9, but this is burned by the heat source by the above-mentioned premixed combustion and is completely burned in the vicinity of the outlet 8.

Next, in order to change the combustion gas temperature at the outlet 8 from 1100 to 1450 ° C, the fuel supply amount from the fuel nozzle 3b was gradually increased, and the NOx amount in the above temperature range was measured. As low as 2.7 ppm at ppm and 1450 ° C was obtained. From the above, by dealing with load fluctuations during start-up and during operation by increasing or decreasing the fuel supply amount to the premix combustion chamber 2d, it is possible to prevent an excessive rise in the catalyst temperature,
It was confirmed that catalytic combustion can always be performed in a stable state.

For comparison, a gas turbine combustor with only catalytic combustion as shown in FIG. 4 is used to increase the fuel supply amount from the fuel nozzle 3a in order to increase the combustion gas temperature at the outlet 8 in the same manner. It was Then, as the supply amount increased, the temperature of the catalyst 9 rose, and the catalyst 9 melted when the combustion gas temperature reached around 1300 ° C, and the high temperature combustion test could not be continued any further. .

[Effects of the Invention] As is clear from the above description, the gas turbine combustor of the present invention includes the combustion tube in which the catalytic combustion chamber and the premixing combustion chamber communicating with the catalytic combustion chamber at the downstream end are independently arranged. First, at the time of starting, it is possible to completely burn the unburned gas by the heat source from the premixed combustion, and after the start, the load fluctuation on the catalyst is changed to increase or decrease the fuel supply amount in the premixed combustion chamber. Can be offset by
As in the conventional case, the temperature of the catalyst is raised without delay, and low NOx combustion is possible without causing deterioration or damage of the catalyst. Moreover, since the structure of the combustor itself is simple, its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a conceptual sectional view showing an example of the structure of a gas turbine combustor of the present invention, FIG. 2 is a conceptual sectional view of an ordinary gas turbine combustor, and FIG. 3 is a temperature distribution of an ordinary gas turbine combustor. FIG. 4 is a characteristic cross-sectional view showing a catalytic combustion type gas turbine combustor, and FIG. 5 is a normal gas turbine combustor (a), a two-stage gas turbine combustor (b) and a catalytic combustion type gas turbine. It is a characteristic view which shows each temperature distribution in a combustor (c). 1,11 …… Gas turbine combustor, 2 …… Combustion tube, 2a, 2c …… Air inlet, 2b …… Catalytic combustion chamber, 2d …… Premixed combustion chamber, 2f …… Expanding part, 3,3a , 3b …… Fuel supply port (fuel nozzle) 4,10 …… Spark plug, 9 …… Catalyst.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kenjiro Igawa 2-4-2 Nishitsutsujigaoka, Chofu-shi Tokyo Electric Power Co., Ltd. Technical Research Laboratory (72) Terunobu Hayata Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi No. 1 in Toshiba Research & Development Co., Ltd. (72) Inventor Tomiaki Furuya No. 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi No. 1 within Toshiba Research & Development Co. Company Toshiba Research Institute (72) Inventor Junji Kozuka, Komukai Toshiba Town, Komukai-shi, Kawasaki-shi 1st, Toshiba Research Institute Co., Ltd. (56) Bibliography Sho 62-81865 (JP, U)

Claims (2)

(57) [Claims] 1. A catalytic combustion chamber (2b) having an air inlet (5), a catalyst (9) and a fuel supply port (3, 3a), and an air inlet (2c) and a fuel supply port separate from the above. (3
b), a combustion pipe (2) having an independent premix combustion chamber (2d) communicating with the catalyst combustion chamber at the downstream end of the catalyst combustion chamber, and a spark plug arranged in the premix combustion chamber (10) A gas turbine combustor, comprising: (10), and at the time of starting, premixed combustion is started by igniting with the spark plug, and then catalytic combustion is started. 2. The gas turbine combustor according to claim 1, wherein a diameter of a passage downstream of a communicating portion between the catalytic combustion chamber and the premixed combustion chamber is expanded.