JPH03260518A - Gas turbine catalyst combustion system - Google Patents

Abstract

PURPOSE:To enable a stable combustion with a low NOx to be attained with high combustion efficiency without being influenced by the deterioration of performance of catalyst by a method wherein a pre-mixing partial combustion is carried out with a main fuel, a not-yet combustion processing is performed at a catalyst combustion region and concurrently a low NOx is attained under a reducing action and the number of operating pre-mixing devices is increased or decreased in response to a variation of load. CONSTITUTION:Pre-mixing gas supplied from pre-mixing devices 81 to 86 performs a pre-mixing partial combustion at a pre-mixing combustion region (a). At this time, a temperature of the combustion gas at an outlet of the pre-mixing combustion region is restricted to 700 to 1,000 deg.C and an amount of discharged NOx is restricted to a low value. Not-yet ignited substances such as a small amount of CO and HC generated under an aforesaid combustion temperature are completely ignited while passing through a catalyst container 11 storing catalyst therein. In turn, as the load is varied, supplying valves 231 to 236 are controlled and the number of main fuel injection nozzles 9 for use in injecting the main fuel is controlled. At this time, the number of released supplying valves 231 to 236 is controlled in such a way as an equivalent ratio of the pre-mixed gas phi is within a range of 0.35 to 0.7. With such arrangement, a combustion with low NOx is maintained and at the same time a high combustion efficiency can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to gas turbine catalytic combustion systems. More specifically, the present invention relates to a gas turbine catalytic combustion system that enables stable and low NOx combustion in a gas turbine with a wide operating range without using a complicated air amount variable mechanism.

[Conventional technology]

Generally, premix combustion and catalytic combustion can achieve low NOx combustion, but there are limits to the ignition temperature and heat resistance temperature, and the stable combustion range is very narrow.

Therefore, in order to achieve high combustion efficiency, flame stability, and low NOx combustion over a wide operating range of the gas turbine,
In order to adjust the equivalence ratio of the premixture, complex flow control is required to adjust the supply amounts of both fuel and combustion air.

For this reason, a complicated flow rate adjustment mechanism is required, and furthermore, relying on catalytic combustion leads to high temperatures and reduced durability.
Pressure loss increases, catalyst performance deteriorates in a short period of time, and combustion efficiency decreases. For this reason, low NO for a long period of time
The drawback was that it was difficult to maintain stable combustion performance with x.

[Problem to be solved by the invention]

The present invention has been made in view of such conventional problems, and its purpose is to provide a gas turbine with a wide operating range that only limits the flow rate of fuel without using a complicated air volume variable mechanism. Less susceptible to catalyst performance deterioration,
An object of the present invention is to provide a gas turbine catalytic combustion system capable of stable, low NOx combustion with high combustion efficiency.

[Means to solve the problem]

That is, the gas turbine catalytic combustion system of the present invention:
A pilot fuel injection nozzle that injects pilot fuel close to the premix combustion area and a plurality of premixers that inject main fuel are installed to perform flame stabilization with viroft fuel and premix partial combustion with main fuel. At the same time, the catalytic combustion area performs unburned treatment and reduces NOx due to the reduction effect.
The present invention is characterized in that the number of operating premixers is increased or decreased in response to changes in load.

The number of premixers described above is preferably 6 to 12, depending on the scale of the gas turbine combustor.

In addition, in the premix partial combustion region, the fuel input from the pilot combustion injection nozzle and the main combustion injection nozzle is
It is desirable to maintain combustion efficiency between 0 and 98%.

〔Example〕

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

In FIG. 1, 1 is a gas turbine catalytic combustor;
A premix combustion zone a and a catalytic combustion zone are arranged inside the inner cylinder 2 as a combustion chamber, and the premix combustion zone a is located upstream of the catalytic combustion zone.

A pilot fuel injection nozzle 4 is provided at the top 3 of the inner cylinder 2 so as to face the premix combustion area a, and the pilot fuel injected into the inner cylinder 2 from the pilot fuel injection nozzle 4 is passed through a swirler 5. Diffusion combustion occurs while mixing with the swirled air. Further, in the vicinity of the pilot fuel injection nozzle 4, a spark plug 6 for igniting the pyro 7) fuel is provided.

Furthermore, six premixers 8, to 86 are installed on the shoulder 7 of the inner cylinder 2.
is provided, and from this premixer 8° to 86 the inner cylinder 2
The premixed mixture supplied into the combustion chamber is partially combusted in a premixed combustion area a. These premixers 81-8
6 are provided at equal intervals on a circle C centered on the pilot fuel injection nozzle 4, as shown in FIG. The premixers 81 to 86 described above are formed from the main fuel injection nozzle 9 and the premixing pipe 10, and the main fuel injected from the main fuel injection nozzle 9 into the premixing pipe 10 is
Before being supplied into the inner cylinder 2, it is mixed with air that has flowed in from the tops of the premixing tubes 81 to 86. The air-fuel mixture flows through the premixture pipe at a flow rate of 50 m/s or more to prevent backfire.

In addition, in the catalytic combustion area, a catalyst container 11 containing a catalyst is provided.
is installed to remove Co generated during premixed partial combustion.
It is designed to completely burn unburned materials such as , HC, etc. Further, in this catalyst section, nitrogen oxides generated in the premix partial combustion section are reduced, thereby further reducing NOx.

The amount of unburned components of this premixed partially combusted combustion gas is considerably small compared to the total input combustion components. Therefore, the amount of catalyst is sufficient for the amount of combustible material, so the combustion load on the catalyst part is small, the pressure loss is small, and the influence of deterioration due to poisoning can be ignored.

Reference numeral 12 denotes an outer cylinder provided outside the inner cylinder 2 and concentrically with the inner cylinder 2, and the air introduced from the air port 13 passes through the passage 14 between the inner cylinder 2 and the outer cylinder 12 and passes through the swirler. -5 and premixer8. ~8a is reached. Also,
The combustion gas is discharged to the outside of the system through a combustion gas outlet 15 communicating with the inner cylinder 2.

FIG. 3 is a schematic diagram showing a fuel supply system, in which a fuel supply pipe 16 connected to the viroft fuel injection nozzle 4 has an amount of fuel supplied from a fuel tank (not shown) toward the viroft fuel injection nozzle 4. Control valve 17 for collective control
and the first pressure gauge 18 are arranged in this order. This control valve 17 is controlled by a governor 19. Moreover, 20.21 is a gate valve disposed before and after the control valve I7.

In addition, six branch pipes 221 to 221 branched from the fuel supply pipe 16
226 includes a supply valve 23. ~23°, respectively, and these supply valves 23, ~236 are connected to the fuel supply pressure Pf of the first pressure gauge 18 and the compressor discharge pressure of the second pressure gauge 24 provided in the inner cylinder 2. It is controlled by the differential pressure ΔPf with respect to the pressure CDP.

Next, combustion control of the gas turbine catalytic combustor mentioned above will be explained.

As described above, fuel injected into the inner cylinder 2 from the pilot fuel injection nozzle 4 provided in the inner cylinder 2 of the gas turbine catalytic combustor 1 is ignited by the spark plug 6 and introduced through the swirler 5. At the same time, the premixed air supplied into the inner cylinder 2 from the premixers 81 to 86 undergoes premixed partial combustion in the premixed combustion area a. At this time, the combustion gas temperature at the outlet of the premix combustion zone is 70
The temperature is kept at 0 to 1000°C, and the amount of NOx discharged is kept low.

In addition, a small amount of C○, HC generated under the above-mentioned combustion temperature
The unburned materials are completely combusted while passing through the catalyst container 11 containing the catalyst.

On the other hand, as the load changes, the supply valve 23. -236 are controlled, and the number of main fuel injection nozzles 9 that inject the main fuel is controlled. At this time, the equivalence ratio φ of the premixture is 0.
Supply valves 231-23 to be within the range of 35-0.7
The number of openings of 6 is controlled. This maintains low NOx combustion and maintains high combustion efficiency.

In the above explanation, the case where only the control valve 17 is controlled by the governor 19 has been explained, but as shown in FIG. The main fuel control valve 27 provided in the pipe 26 may also be controlled by the governor 19.

〔Effect of the invention〕

As described above, the present invention provides a pilot fuel injection nozzle that injects pilot fuel close to the premix combustion region and a plurality of premixers that inject main fuel, performs flame stabilization with the pilot fuel, Premixed partial combustion is performed using the main fuel, unburned processing is performed in the catalytic combustion area, and at the same time low NOx is achieved by reduction action, and the number of operating premixers is increased or decreased in response to load fluctuations. Since the,
Stable, low-NOx combustion that is less susceptible to catalyst performance deterioration is now possible over a long period of time in a gas turbine with a wide operating range, without using a complicated air amount variable mechanism.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a gas turbine catalytic combustor used in a gas turbine catalytic combustion system according to the present invention, FIG. 2 is a sectional view taken along line nn in FIG. FIG. a... Premix combustion area, b... Catalytic combustion area, 1...
Gas turbine combustor, 4... Pilot fuel injection nozzle, 81-86... Premixer.

Claims (1)

[Claims] A gas turbine catalytic combustion system having a premix combustion zone and a catalytic combustion zone disposed downstream of the premix combustion zone, the system comprising a pilot fuel injection nozzle for injecting pilot fuel toward the premix combustion zone and a main fuel. The pilot fuel is used to stabilize the flame, the main fuel is used to perform premixed partial combustion, and at the same time, the unburned area is treated in the catalytic combustion area, and at the same time, the reduction effect reduces NOx.
A gas turbine catalytic combustion system in which the number of operating premixers is increased or decreased in response to changes in load.