JPH06229554A - Burner for gas turbine - Google Patents

Abstract

PURPOSE:To improve durability of a catalyst and suppress production of NOx by making a temperature distribution of the catalyst provided in a gas passage uniform. CONSTITUTION:A burner for a gas turbine supplies fuel gas 2 and the air into a burner body 1, and burns mixed gas by a catalyst 11 provided in a gas flow passage. The catalyst 11 has a honeycomb structure in such a manner that number of cells per unit area of its center is less than that of cells at a periphery.

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 in which fuel is combusted by using a catalytic body, and more particularly to a gas turbine combustor used in a gas turbine power generation system or the like, which produces a small amount of nitrogen oxide (NOx). .

[0002]

2. Description of the Related Art In recent years, with the depletion of petroleum resources and the like, various alternative energies are required, and at the same time, efficient use of energy resources is also required. A gas turbine / steam turbine combined cycle power generation system that uses natural gas as a fuel or a coal gas turbine / steam turbine combined cycle power generation system can meet these requirements.

These gas turbine / steam turbine combined cycle power generation systems have higher power generation efficiency than conventional power generation systems using steam turbines that use fossil fuels, and therefore, natural gas or gas whose production is expected to increase in the future is expected. It is expected as a power generation system that can effectively convert fuel such as coal gas into electric power.

In the gas turbine combustor used in such a gas turbine power generation system, conventionally, a mixed gas of fuel and air is ignited by using a spark plug or the like,
It burns uniformly.

FIG. 6 shows an example of a conventional gas turbine combustor. In this gas turbine combustor, the fuel 4 injected from the fuel nozzle 2 mounted on the combustor body 1 into the combustor inner cylinder 3 as shown in FIG. It is mixed with the air 6 supplied through it, communicates with the combustor inner cylinder 3, and is ignited by the spark plug 7 attached to the combustor body 1 to burn.
Then, the combustion gas is cooled and diluted to a predetermined turbine inlet temperature by adding cooling air from the upstream air supply port 5 and dilution air from the downstream air supply port 5, and then from the turbine nozzle 8. It is injected into the gas turbine. In the figure, 9 is a swirler for maintaining flame holding after ignition of the mixed gas.

One of the serious problems in the conventional gas turbine combustor is that a large amount of NO is generated when the fuel is burned.
x is generated and adversely affects the environment such as pollution. The reason why this NOx is generated is that there is a high temperature part where the temperature inside the combustor partially exceeds 2000 degrees during fuel combustion.

In order to solve the above problems of the gas turbine combustor, various combustion methods have been studied, and recently, a catalytic combustion method using a solid phase catalyst has been proposed.
In this catalytic combustion system, a catalyst body is provided on the gas flow path to burn a lean fuel that is not burned by an ordinary combustor. Therefore, in this catalytic combustion type combustor, the combustion temperature is not so high as to generate NOx, and the turbine inlet temperature can be the same as the conventional one.

[0008]

However, the above-mentioned catalytic combustion type combustor also has the following problems. That is, if there is a distribution of the fuel concentration, temperature and flow velocity of the mixed gas at the catalyst inlet, there is a difference in the degree of catalytic combustion in the cross section of the catalyst body. As a result, a temperature distribution is generated in the cross section of the catalyst body, and the durability of the catalyst body becomes a problem from the viewpoint of heat resistance and thermal stress of the catalyst body.

In order to solve such a problem, the fuel nozzle has been improved to considerably improve the uniformity of the concentration distribution. Further, with respect to the flow velocity distribution, the catalyst acts as a flow resistance and generally causes a pressure loss of about 5%, so that it can be rectified by the catalyst and can be made considerably uniform. However, regarding the temperature distribution, considering the heat resistance of the inner cylinder of the combustor, it is necessary to cool the inner cylinder, and therefore the distribution is such that the central portion is high and the peripheral portion is low. Therefore, catalytic combustion is more likely to occur at higher temperatures,
The catalyst temperature distribution is further amplified, and there is a problem that the central portion becomes high and the peripheral portion becomes low.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to make the temperature distribution of the catalyst uniform and to improve the durability of the catalyst and suppress the generation of NOx. A gas turbine combustor is provided.

[0011]

SUMMARY OF THE INVENTION The present invention provides a gas turbine combustor in which fuel gas and air are supplied into a combustor body, and a mixed gas of these is burned by a catalyst provided in a gas flow passage. In the above, the combustion body has a honeycomb structure, and the number of cells per unit area of the central portion is smaller than the number of cells in the peripheral portion.

[0012]

In the gas turbine combustor having such a structure, since the burning rate of the catalyst is proportional to the amount of catalyst per unit volume and the temperature, the number of cells in the central portion of the catalyst is small and the number of cells in the peripheral portion is small. By increasing the number of cells, the catalytic combustion progresses smoothly, the temperature distribution in the cross section of the catalyst can be made uniform, and the amount of NOx generated can be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of a gas turbine combustor adopting the catalytic combustion system according to the present invention. In FIG. 1, the same parts as those in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted. Only different points will be described here. In this embodiment, as shown in FIG. 1, a sub-combustion nozzle 10 is provided in the middle of the combustor inner cylinder 3, and a catalyst body 11 is provided on the gas flow path. As shown in FIG. 2, the catalyst body 11 has a honeycomb structure filled with a combustion catalyst, and has a smaller number of cells (the number of cells per unit area) in the central portion of the catalyst body 11 than in the peripheral portion.

In such a combustor, when starting,
Fuel and air are supplied from the fuel supply nozzle 2 and the air supply port 5, respectively. The mixed gas of fuel and air is ignited by the spark plug 7, and the swirler 9
The temperature is raised to some extent while being stabilized by the flame. In this case, the amount of air supplied from the air duct 12 through the plurality of air supply ports 5 into the combustor inner cylinder 3 is
It is determined by the opening area of each air supply port 5 and the pressure difference inside and outside the combustor inner cylinder 3 at that position. Further, the temperature rise of the gas by this combustion is carried out in order to raise the temperature of the gas to a temperature at which the catalytic combustion in the catalyst body 11 works so that the catalytic combustion proceeds smoothly, and it is not always necessary depending on the type of fuel and catalyst. Not.

Fuel from the auxiliary fuel nozzle 10 and air from the air supply port 5 are supplied and mixed with the heated gas, and the mixed gas resulting from this mixing is supplied to the catalyst body 11.
This is what causes catalytic combustion. In this case, the catalyst body 1
At the inlet of No. 1, even if the temperature of the gas in the peripheral portion is lower than that in the central portion, the number of cells in the central portion of the catalytic body 11 is smaller than that in the peripheral portion, so that catalytic combustion proceeds smoothly in the peripheral portion.

In FIG. 2, the change in the number of cells in the cross section of the catalyst body 11 is shown by two types, but it is not limited to this, and in particular when the distribution of gas temperature at the catalyst inlet is large, It is preferable to increase the number of types.

FIG. 3 is a sectional view showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Only different points will be described here. Although the present embodiment is the same in that the catalyst body 11 having the structure shown in FIG. 2 is provided on the gas flow path of the combustor inner cylinder 3 as shown in FIG. 3, the durability of the catalyst body 11 is further improved. In order to improve the gas, a gas provided with a fuel nozzle 13 and a spark plug 14 downstream of the catalyst body 11 and a valve 16 for adjusting the amount of dilution air supplied through the air supply port 15 of the combustor inner cylinder 3 on the downstream side thereof. A phase combustion unit is provided to reduce the heat load on the catalyst body 11 by combining combustion in the catalyst body 11 and gas phase combustion downstream of the catalyst body 11.

In such a combustor, first, a mixed gas of fuel and air is burned by the catalyst 11. In this case, since the catalyst body 11 has a small number of cells in the central portion and a large number of cells in the peripheral portion, even if the temperature of the gas in the peripheral portion is lower than that in the central portion at the catalyst inlet, catalytic combustion in the peripheral portion is smooth. Proceed to.

Normally, in the catalyst body 11, combustion by catalytic reaction and gas-phase combustion occur at the same time, but in the present embodiment, fuel concentration, temperature, flow velocity, etc. of the mixed gas are generated so that only combustion by catalytic reaction occurs. Are controlling.
Therefore, since the catalyst body 11 is not accompanied by the vapor phase combustion, it does not reach a high temperature, and only a part of the fuel burns, and the combustion gas containing unfuel is discharged from the catalyst body 11.

In the present embodiment, by adding new fuel to the combustion gas discharged from the catalyst body 11 from the fuel nozzle 13 provided on the downstream side of the catalyst body 11 as shown in FIG. The fuel concentration in the gas was increased to cause vapor-phase combustion on the downstream side of the catalyst body 11, enabling the combustion gas to have a high temperature. Further, the temperature of the injection gas to the turbine can be adjusted by adjusting the opening of the valve 16 to adjust the amount of diluted air from the air supply port.

The spark plug 14 is used for ignition of vapor phase combustion on the downstream side of the catalyst body 11, although it is not always necessary depending on the type of fuel and combustion conditions. As a result, deterioration of the catalyst body 11 at high temperatures can be eliminated, the durability of the catalyst body can be improved, and low NOx combustion can be achieved. Here, an experimental example based on specific numerical values will be described with reference to FIG. 4 showing the gas turbine combustor of FIG. 3 as a schematic diagram.

In the gas turbine combustor shown in FIG.
As the catalyst body 11, a honeycomb structure having a ceramic carrier having a length of 90 mm and a diameter of 300 mm on which a noble metal is supported is used. The number of cells within a circle of 115 mm from the center of the catalyst body was 200 (cells / in ² ), And the number of cells around it was 400. The test was performed under atmospheric pressure, the fuel was natural gas, and the catalyst inlet gas flow rate was 30 m 2 / s. In addition, the preferred temperature range of the gas mixture at the catalyst inlet when stable catalyst combustion is obtained is
A test confirmed that the temperature was 400 ° C to 450 ° C, and the temperature was raised to 450 ° C here. Fuel-air ratio (F /
A, volume ratio) was set to 0.03 so that the temperature of the catalyst body 11 was 1000 ° C. or lower.

Further, the fuel was supplied from the fuel nozzle 13 so that the gas-phase combustion temperature generated after the catalytic combustion was 1500 ° C. in view of the relationship between the generation of NOx and the combustion temperature. The temperature of the catalyst body 11 was measured at the catalyst outlet surface, and R type sheath thermocouples having a diameter of 1 mm were embedded at 40 locations. Combustibility was also investigated by measuring the gas composition at the combustor outlet. For comparison, a combustion test was also conducted using a conventional catalyst body using the same cell on the entire surface. In this case, the number of cells was 200.

When an experiment was carried out based on such specific numerical values, the catalyst temperature distribution in the case of using the catalyst body according to the present invention was the result as shown in FIG. 5 (a).
FIG. 5B shows the catalyst temperature distribution when the conventional catalyst body is used.
The results are shown in. That is, in the case of the present invention, the combustion efficiency is 99% or more and NOx is 4 ppm, whereas the conventional catalyst body has a combustion efficiency of 98.5% and NOx is 9 ppm, and the present invention has a higher combustion efficiency. It can be seen that it is high and the amount of NOx generated is small.

[0026]

As is apparent from the above description, in the catalytic combustion type gas turbine combustor according to the present invention, the temperature of the peripheral portion of the catalyst body is higher than that in the conventional case, and the generation of high temperature parts is suppressed. It is possible to improve the uniformity of the temperature distribution in the cross section of the catalyst body. Further, when the catalyst body of the present invention is used, the combustion efficiency and the suppression of NOx are improved as compared with the case where the conventional catalyst body is used, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a gas turbine combustor according to the present invention.

FIG. 2 is a cross-sectional view of a catalyst body according to the example.

FIG. 3 is a vertical sectional view showing another embodiment of the present invention.

FIG. 4 is a schematic diagram of a gas turbine combustor for explaining an experimental example based on specific numerical values of the present invention.

5 is a diagram showing a temperature distribution of a catalyst body according to the experimental example of FIG.

FIG. 6 is a vertical sectional view of a conventional gas turbine combustor.

[Explanation of symbols]

1 ... Combustor body, 2, 10, 13 ... Fuel nozzle, 3
...... Combustor inner cylinder, 4 ... Fuel, 5 ... Air supply port, 6 ...
... air, 7 ... spark plug, 8 ... turbine nozzle, 9 ... swirler, 11 ... catalytic body, 12 ... duct.

Claims (1)

[Claims] 1. A gas turbine combustor in which fuel gas and air are supplied into a combustor body and a mixed gas of these is burned by a catalyst provided in a gas flow passage, wherein the catalyst is a honeycomb. A gas turbine combustor having a structure, wherein the number of cells per unit area in the central portion is smaller than the number of cells in the peripheral portion.