JPH06129262A - Fuel controller of combustor for gas turbine - Google Patents

Abstract

PURPOSE:To provide a device which can control a combustor capable of being driven with a low NOx at a high combustion efficiency regardless of load. CONSTITUTION:A distributing device 2 is branched into a pilot fuel line 5 and a premixed air-fuel mixture line 6 provided with a gate valve 10, wherein the pilot fuel line 5 is provided with a first switching valve 7 and a fixed flow rate valve 8, and the premixed air-fuel line 6 comprises lines 11, 12, 13 whose one-side ends are connected to the back stream side of the gate valve 10, while the other-side ends are connected to a fuel injection nozzle 56 of a premixed airfuel supplying pipe, and branched lines 11b, 12b 13b branched from the lines 11, 12, 13, and connected to the fuel injection nozzle 56. A second switching valve 14 is arranged in the branched line 11b of the line 11, while third and fourth switching valves 15, 16 are respectively arranged on the lines 12, 13. The first switching valve 7 comprises a valve making its action reverse to that of the gate valve 10, and respective switching valves are so constituted as to be operated by a fuel distribution controller 17 operated by receiving the signal from the controller of the gas turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for a gas turbine, and more particularly to a fuel control device for a gas turbine having a pilot valve for directly injecting fuel and a premixing supply pipe for premixing air and fuel for combustion. The present invention relates to a control device.

[0002]

2. Description of the Related Art A combustor in which fuel is directly injected into a combustion cylinder for combustion has excellent ignition performance and flame holding performance. But,
This combustor has a problem that it produces a high concentration of NOx because it burns at a high temperature. To solve this problem, a method of injecting water or steam into the combustor to lower the combustion temperature is adopted. However, this method requires a pure water supply device and the like in addition to reducing the thermal efficiency.

On the other hand, there has been proposed a combustor in which air and fuel are mixed in advance, and the mixture is supplied to a combustor and burned to burn at a relatively low temperature to reduce NOx. The burner has a narrow stable combustion range because it controls the combustion temperature by adjusting the fuel concentration to the optimal state (thinner) for combustion, and therefore, it has a stable and low NOx state in a wide operating range like a gas turbine combustor. In order to burn, it is necessary to accurately adjust the equivalence ratio of the premixed gas, and as a result, there is a problem that complicated flow rate control for adjusting the flow rates of fuel and combustion air is required.

Due to such requirements, the inventor of the present invention arranges a combustion cylinder 52 having a pilot valve 51 at the central top of the combustor body 50 as shown in FIG. 2, and forms the diffusion region A with the combustion cylinder 52. The small-diameter portion 53, the intermediate conical portion 54 that forms the air-fuel mixture combustion region B, and the large-diameter portion 55 that forms the main combustion region C, and the fuel supplied from the combustion air a and the fuel injection nozzle 56. A gas turbine combustor was constructed in which six premixed gas supply pipes 57 were arranged at equal intervals in the horizontal direction so that F ₁ was premixed and supplied to the premixed combustion region B as a premixed gas F ₂ . . And the fuel of the combustor in which the pilot valve and the plurality of premixed gas supply pipes are arranged is extremely excellent in responsiveness
A fuel control device for a gas turbine combustor that can be easily controlled was previously proposed as Japanese Patent Application No. 4-83975.

That is, this fuel control device for a gas turbine combustor is further connected to a fuel amount control device for a gas turbine combustor having a flow rate control valve, and this fuel distribution device is additionally connected. A device for controlling fuel supplied to a combustor via the distribution device, wherein the distribution device is branched into a pilot fuel line and a premix gas line having a sluice valve,
The pilot fuel pipe line has a first switching valve and a constant flow valve, and the premix combustion pipe line passes through the pipe lines provided with the second, third and fourth switching valves, respectively, and the premixed gas mixture is supplied. The first switching valve is connected to the fuel injection nozzle of the supply pipe, and the first switching valve and the second switching valve are reversely operated. The switching valves receive signals from the control device of the gas turbine. It is configured to be operated by an operating fuel distribution control device.

In this fuel control device, the pilot valve supplies less fuel than in the flame-holding state or no-load operation in the rated load operation to burn the fuel. Therefore, the fuel injected from the pilot valve generates NOx at a high temperature. But the amount is small. And since the premixed fuel injection nozzles 56 are operated and burned one after another according to the output of the turbine, it is possible to perform low NOx combustion even in a high output state.
Since a large number of switching valves control only the number of actuated valves without substantially controlling the flow rate, the flow rate of fuel and its distribution can be controlled relatively well.

[0007]

In the fuel control device for the gas turbine combustor proposed above,
Since the fuel distribution control device is designed to control the fuel supply amount in units of a plurality of fuel injection nozzles, specifically, two fuel injection nozzles, a predetermined fuel control cannot be achieved sufficiently, so that a low NO There was a problem that the combustion range where the combustion efficiency was high at _x , that is, the operating range was narrow.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a fuel quantity control device 1 for a gas turbine combustor having a flow control valve 1c is provided with Distributor 2 is additionally connected to control fuel supplied to combustor 50 via fuel distributor 2, said distributor 2 being a pilot fuel line 5.
And a premix gas line 6 having a sluice valve 10, the pilot fuel line 5 has a first switching valve 7 and a constant flow valve 8, and the premix gas line 6 has the sluice valve 10 Of the pipes 11, 12, 13 having one end connected to the wake side and the other end connected to the fuel injection nozzle 56 of the premixed gas supply pipe 57 and the pipes 11, 12, 13
A branch line that is branched from and is connected to the fuel injection nozzle 56.
11b, 12b, 13b, the second switching valve 14 is provided in the branch line 11b, and the third and fourth switching valves 15, 16 are provided in the lines 12 and 13.
And the first switching valve 7 is a sluice valve.
Of the combustor for a gas turbine configured to be operated by a fuel distribution control device 17 that operates by receiving a signal from the control device of the gas turbine. It is intended to provide a fuel control device.

[0009]

[Operation] According to the fuel control device for the gas turbine combustor, the fuel is supplied to one fuel injection nozzle 56 by opening and closing the second switching valve 14 provided in the branch pipeline 11b of the pipeline 11. Therefore, even if the fuel supply to the two fuel injection nozzles 56 is controlled by the third and fourth switching valves 15 and 16 provided in the other pipelines 12 and 13, respectively. The combination of these makes it possible to control the fuel supply in six stages, and as a result, the accuracy is improved and low NO _x and high fuel efficiency can be maintained over a wide range.

[0010]

EXAMPLES Next, examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a fuel control device for a gas turbine combustor according to the present invention. In the preceding stage, a gas turbine combustor for controlling and shutting off the fuel supplied to the combustor body 50 shown in FIG. A fuel amount control device 1 is provided, and a fuel distribution device 2 added in the present invention is provided at a subsequent stage of the fuel control device 1.

The conventional fuel control device 1 has a front and rear sluice valve 1
a and 1b are arranged in the main fuel line 3 having a flow control valve 1c, and a sluice valve 1a when the flow control valve 1c is closed.
And an exhaust pipe 4 having a sluice valve 1d for discharging the fuel remaining between the flow control valve 1c and the flow control valve 1c, and a control device (not shown) for controlling these according to the operating state of the turbine. There is. The fuel control device 1 is attached to a conventional gas turbine combustor,
It has various configurations depending on the equipment.

In the fuel distribution system 2, the main fuel line 3 is branched into a pilot fuel line 5 and a premixed gas line 6. The pilot fuel line 5 has a first switching valve 7 and a spring pressure. A constant flow valve 8 whose flow rate is automatically determined is provided alongside, and a pipe line 9 for integrally supplying fuel to the pilot valve 51 is provided on the downstream side thereof. Further, an electromagnetic sluice valve 10 is provided in the premix air pipe 6, and the downstream of the solenoid sluice valve 10 is branched into a plurality of pipe lines 11, 12, 13.
13 is connected to the fuel injection nozzle 56.

Further, one end of each of the pipelines 11, 12 and 13 is connected to the fuel injection nozzle 56, and branch pipelines 11a and 11
The other ends of b, 12a, 12b, 13a, 13b, ... Are connected, and in particular, a second switching valve 14 is provided in this branch conduit 11b. In addition, a third switching valve 15 and a fourth switching valve 16 are provided in the pipelines 12 and 13, respectively. The sluice valve 10 and the first switching valve 7 are "reverse operating" valves, and when the first shunting valve 7 is closed, the sluice valve 10
When the first switching valve 7 opens, the sluice valve 10 operates so as to close.

That is, A) Fuel is supplied to the pilot valve 51 from both the constant flow valve 8 and the first switching valve 7, and the fuel is supplied from the flame-retained state (fuel ratio of about 15%) to the half output (half load, half load, It operates to generate turbine output up to 25%). B) Next, fuel is simultaneously supplied to the fuel injection nozzle 56 from the pipe 11a, and is controlled so as to handle a load of about 50% of the turbine output.

C) When more output is required,
Each switching valve 14 provided in the branch pipe 11b or the pipes 12, 13
It is configured so that the fuel supply to the fuel injection nozzle 56 attached to the premixed gas supply pipe 57 can be switched by operating 15 and 16. D) On the contrary, the turbine output decreases and the electromagnetic gate valve
When the valve 10 is closed, the first switching valve 7 is opened together with the closing of the electromagnetic gate valve 10.

This electromagnetic sluice valve 10 is also used as an emergency shutoff valve, and is closed at the time of an emergency shutoff such as when the output of the turbine suddenly drops or some accident occurs, and the second to fourth switching valves 14,
It has the function of shutting off fuel to 15 and 16 all at once. on the other hand,
The second to fourth switching valves 14, 15, 16 are closed within about 1 second when the electromagnetic sluice valve 10 is closed, and when the electromagnetic sluice valve 10 is opened, the fuel in the pipelines 11, 12, 13 is released. It is designed to operate so that it is shut off.

The second switching valve 14 supplies fuel supplied to one fuel injection nozzle 56 connected to the branch pipe 11b, and the third and fourth switching valves 15 and 16 are combustors. Two fuel injection nozzles 56 arranged on the diameter of the main body 50 are used as a pair to control the fuel supplied to the branch lines 12a, 12b, 13a, 13b. Further, 17 is a fuel distribution control device, and 18 and 19 are pressure converters.

That is, as shown in FIG. 3, the switching valves 7,
The fuel is selectively supplied to any one to six fuel injection nozzles 56 by a load signal or the like by operating 10, 14, 15, and 16. The switching valve 7 and the switching valve 10
It has been shown to work in reverse. Then, the fuel distribution control device 17 has a load cutoff signal S ₁ , a load signal S ₂ , an atmospheric temperature S ₃ , and a CDP signal S ₄ via a pressure converter 19.
It is configured to receive signals such as the differential pressure signal S ₅ between the fuel pre-pressure and the CDP via the pressure converter 18 and control the switching valves 7, 14, 15, 16 and the electromagnetic sluice valve 10. Further, the pressure signal can be used for the same control as the load signal, as opposed to the fuel control when there is no load signal.

Next, the concept of controlling the fuel supplied to the gas turbine combustor by the apparatus according to the present invention will be described with reference to FIGS. 4 and 5. [Burning state to turbine low output state] Figure 4 shows the turbine load on the horizontal axis and the combustion efficiency (%) on the vertical axis. The valve 8 alone, or the constant flow valve 8 and the first switching valve 7 are opened to open the combustor.
It is configured to control the flow rate of the fuel supplied to the pilot valve 51 of 50. [Turbine output change state] The first switching valve 7 is closed, and the electromagnetic sluice valve 10 provided on the upstream side of the branch pipe 6 is instantaneously reverse-operated and opened. In this case, it corresponds to a load of about 25%. Further, the second switching valve 14 and the third switching valve 15
Then, the fuel supply amount is sequentially increased by the fourth switching valve 16 and controlled so as to obtain the turbine output corresponding to the fluctuation of the load.

This state is shown in FIG. 4 as 1 to 6 and the curve of the number of premixed gas pipes (fuel injection nozzles) and the manner in which the combustion efficiency changes in a sawtooth shape when the number is changed. It can be seen that the combustion efficiency temporarily decreases when the number of fuel injection nozzles changes, but the combustion efficiency gradually increases as the load increases, and the maximum combustion efficiency corresponding to the number is obtained. FIG. 5 is a diagram in which the vertical axis represents the amount of NO _x generated in the exhaust gas and the horizontal axis represents the load. NO _x gradually increases as the load increases in a predetermined number of fuel injection nozzles. However, it means that the NO _x can be controlled so as not to exceed 30 ppm by switching the number before 30 ppm. That is, the low NO _x operation can be performed by controlling the number of premixed gas pipes, that is, the number of fuel injection nozzles that are operated according to the load. [Emergency cutoff state] When the load on the gas turbine suddenly decreases or when an emergency stop condition occurs, the load cutoff signal S
₁ is added to the fuel distribution control device 17, and the electromagnetic sluice valve 10 is actuated to instantly shut off the premixed gas line 6.

Then, the fuel in the pipelines 11, 12 and 13 which has been supplied with the fuel from the pipeline 6 is cut off, and the fuel injection nozzle
56 stops working. Immediately after that, the second switching valve 14, the third switching valve 15 and the fourth switching valve 16 are closed. However, in this state as well, fuel is supplied to the pilot valve 51 through the constant flow valve 8, and the first switching valve 7 that operates in reverse with the closing of the electromagnetic sluice valve 10 opens to provide a flame-retained state or a minimum state. The output status of is retained.

In the above embodiment, the premixed gas pipeline 6 is branched into the pipelines 11, 12 and 13, and the switching valves 14, 15, 15 are connected to these.
Although the example in which 16 is provided is shown, these numbers are appropriately determined depending on the scale of the combustor 50 and the like, and the premixed trachea 6 is not limited to the above-mentioned embodiment.

[0023]

In the fuel control device for a gas turbine combustor according to the present invention, a fuel distribution device 2 is additionally connected to the fuel amount control device 1 for a gas turbine combustor having a flow control valve 1c. A device for controlling the fuel supplied to the combustor 50 via the fuel distribution device 2, said distribution device 2 comprising:
It is branched into a pilot fuel pipe line 5 and a premix gas pipe line 6 having a sluice valve 10. The pilot fuel pipe line 5 has a first switching valve 7 and a constant flow valve 8, and the premix gas pipe line 6 is provided. Is a conduit 11, 12, one end of which is connected to the downstream side of the gate valve 10 and the other end of which is connected to the fuel injection nozzle 56 of the premixed gas supply pipe 57.
13 and the pipes 11, 12 and 13 are branched off, and a fuel injection nozzle 56
Branch lines 11a, 11b, 12a, 12b, 13a, connected to
13b and the second switching valve 14 in the branch pipe 11b.
The third and fourth switching valves 15 and 16 are arranged in the pipe lines 12 and 13, respectively, and the first switching valve 7 and the sluice valve 10 are configured to operate in reverse. Is a fuel distribution controller 17 that operates by receiving a signal from the controller of the gas turbine.
Is configured to be activated by.

Therefore, the pilot valve that easily generates NOx
Fuel is supplied to 51 from the first switching valve 7 and the constant flow valve 8, so that the flame-maintained state and the low-load state are maintained. At a higher output, it is possible to selectively supply fuel to the fuel injection nozzles 56 of the plurality of premixed gas supply pipes 57 in the above embodiment, specifically, one to six, so that it is wide. There is an effect that not only can combustion be performed with low NO _x , stable and high combustion efficiency over the operating range, and efficient fuel control can be performed.

[Brief description of drawings]

FIG. 1 is a piping diagram of a fuel control device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a gas turbine combustor used in the present invention.

FIG. 3 is a diagram showing a relationship between a switching valve and a fuel injection nozzle.

FIG. 4 is a diagram showing a relationship between combustion efficiency and load.

FIG. 5 is a diagram showing the relationship between the amount of NO _x generated and the load.

[Explanation of symbols]

50 Combustor body 51 Pilot valve 52 Combustion cylinder 56 Fuel injection nozzle 57 Premixed gas supply pipe 1 Fuel control device 2 Fuel distribution device 3 Main fuel pipe line 5 Pilot fuel pipe line 6 Premixed gas pipe line 7 First switching valve 8 Fixed Flow valve 9 Pipe line 10 Electromagnetic gate valve 14 2nd switching valve 15 3rd switching valve 16 4th switching valve 17 Fuel distribution control device

Claims (1)

[Claims] 1. A fuel distribution device 2 is additionally connected to a fuel amount control device 1 of a gas turbine combustor having a flow control valve 1c, and is supplied to a combustor 50 via this fuel distribution device 2. A device for controlling fuel, wherein the distributor 2 is branched into a pilot fuel line 5 and a premix gas line 6 having a sluice valve 10, and the pilot fuel line 5 is fixed to a first switching valve 7. A flow passage 8 having a flow valve 8, one end of which is connected to the downstream side of the sluice valve 10 and the other end of which is connected to the fuel injection nozzle 56 of the premixed gas supply pipe 57. , 12,
13 and the pipes 11, 12 and 13 are branched off, and a fuel injection nozzle 56
And branch pipes 11b, 12b, 13b connected to
The second switching valve 14 is connected to the branch line 11b of the line 11,
Second and third switching valves 15 and 16 are arranged on the second and the third switching valves, respectively, and the first switching valve 7 is constituted by a valve that operates in reverse to the sluice valve 10. The switching valves and the like control the gas turbine. A fuel control device for a gas turbine combustor configured to be operated by a fuel distribution control device (17) which operates in response to a signal from the device.