JPH08312377A - Multinozzle type combustor for gas turbine - Google Patents

Abstract

PURPOSE: To enable changeover control of stable fuel distribution by reducing a fuel supply to a first main nozzle group simultaneously with the start of fuel supply to a second main nozzle group at the time of increasing load from an operating state of intermediate output by a pilot nozzle and a first main nozzle. CONSTITUTION: A fuel supply control system inclusive of a fuel distribution control circuit 6 receiving a control output signal from a minimum selector circuit 5 is provided with a pilot nozzle fuel supply control circuit 7P and both first and second main nozzle group fuel control circuits 7A and 7B. In a range from the initial stage of operation of a fueler to the first intermediate output, a fuel supply to the first main nozzle group is increased by degrees. Likewise at the time of arrival to the intermediate output, a fuel supply to the second main nozzle group is started, while the fuel supply to the first main nozzle group is reduced as far as being commensuable to a fuel supply portion for the second main nozzle group, and subsequently the fuel supply to both these main nozzle groups is reduced, but after that each of fuel supply quantities to both these groups is gradually increased the other way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle type combustor for a gas turbine, and more particularly to a multi-nozzle type combustor having a plurality of main nozzles near a pilot nozzle.

[0002]

2. Description of the Related Art Generally, in a multi-nozzle type combustor for a gas turbine, as shown in FIG. 5, a plurality of main nozzles 2 surrounding a pilot nozzle 1 inside a combustor inner cylinder 3 are provided.
A and 2B are provided to share the combustion zone, and these main nozzles are connected to the first main nozzle group 2A and the second main nozzle group 2A.
It is divided into a main nozzle group 2B. Reference numeral 4 in FIG. 5 indicates a swirler for making a premixed mixture of fuel and air into a swirling flow.

In the conventional combustor of this type, the fuel system has three systems of a pilot fuel system, a fuel system for the first main nozzle group and a fuel system for the second main nozzle group, and about 30 from ignition. Up to the% load, the pilot fuel and the fuel for the first main nozzle group are covered, and when the load is exceeded, the fuel for the second main nozzle group is supplied.

[0004]

The conventional multi-nozzle type combustor for a gas turbine as described above has the following problems. (1) Gas turbine fuel control uses a control output signal (CSO;
Control Signal Output), but CSO and gas turbine load do not always match exactly. Therefore, when switching fuel, stagnation occurs before and after opening / closing of the fuel valve in the second main nozzle group,
If the switching is not performed smoothly and is extremely heavy, the load may fluctuate at the time of switching and the control characteristics may become unstable. (2) The fuel control valve for the pilot nozzle, the fuel control valve for the first main nozzle group and the fuel control valve for the second main nozzle group have different valve characteristics, and the sum of the fuel gas flowing through each valve is the gas. Involved in turbine load. Therefore, when there are variations in the valve characteristics, particularly the valve CV value (valve capacity coefficient), it takes a long time to adjust, and particularly in a plant having a plurality of gas turbines such as a combined plant, valve adjustment is difficult. .

The present invention is intended to solve the above-mentioned problems, and it is a gas that can smoothly shift to a fuel distribution schedule after fuel switching of a main nozzle group surrounding a pilot nozzle. An object is to provide a multi-nozzle type combustor for a turbine.

[0006]

In order to achieve the above-mentioned object, a multi-nozzle type combustor for a gas turbine of the present invention comprises:
In a multi-nozzle type combustor for a gas turbine, comprising a pilot nozzle and a first main nozzle group and a second main nozzle group, each of which includes a plurality of main nozzles installed near the pilot nozzle,
A fuel supply control system for controlling the fuel supply amounts to the pilot nozzles, the first main nozzle group, and the second main nozzle group to be distributed according to a control output signal is provided, and the control system controls the combustion. The fuel supply amount to the first main nozzle group is gradually increased from the initial operation of the reactor to the predetermined first intermediate output, and when the first intermediate output is reached, the fuel supply to the second main nozzle group is started. At the same time, the fuel supply amount to the first main nozzle group is reduced by an amount commensurate with the fuel supply amount to the second main nozzle group, and thereafter, the fuel supply amounts to the first and second main nozzle groups until the maximum output. Has a load increasing control characteristic for gradually increasing the load, and when the load is reduced from a high load state, up to a predetermined second intermediate output slightly lower than the first intermediate output. The fuel supply amount to each of the first and second main nozzle groups is gradually decreased, and when the second intermediate output is reached, the fuel supply amount to the second main nozzle group is stopped and the fuel amount is supplied to the second main nozzle group. Of the fuel supply amount to the first main nozzle group is increased by commensurate with the fuel decrease amount when the fuel supply is stopped, and then the fuel supply amount to the first main nozzle group is gradually reduced until the output is zero. It is characterized by having

Further, in the multi-nozzle type combustor for a gas turbine of the present invention, the fuel supply control system has a fuel distribution control circuit which receives the control output signal in the pilot nozzle, the first main nozzle group and the second main nozzle group. It is configured such that each control circuit for the flow rate control valve in each fuel supply path to the main nozzle group is connected and a valve opening correction function circuit is connected to the fuel supply control circuit. I am trying.

[0008]

In the above-described multi-nozzle combustor for a gas turbine of the present invention, the fuel supply amounts to the pilot nozzles, the first main nozzle group and the second main nozzle group are controlled so as to be distributed according to the control output signal. When the fuel supply control system increases the load from the operation state of the pilot nozzle and the first main nozzle at the predetermined first intermediate output, the fuel supply control system starts to supply the fuel to the second main nozzle group, and at the same time, the increased amount is satisfied. Only by reducing the fuel supply amount to the first main nozzle group, the switching control can be stably performed.

Further, when the load is sequentially reduced from the high load state, when the load is further reduced from the operating state at the predetermined second intermediate output, the fuel supply to the second main nozzle group is stopped and the load is reduced at the same time. By increasing the fuel supply amount to the first main nozzle group in proportion to the amount, the switching control can be stably performed. Since the second intermediate output is set to a level lower than the predetermined first intermediate output, hysteresis is formed in the above-described fuel switching characteristic, so that the first intermediate output and the second intermediate output described above are formed. Even if a load change occurs near the output, it is possible to prevent hunting in which the above-described fuel switching operation is frequently performed.

Further, the fuel supply control system includes a valve opening correction function in each control circuit for the flow rate control valve in each fuel supply path to the pilot nozzle, the first main nozzle group and the second main nozzle group. When a circuit is provided, an appropriate control signal is output according to the valve characteristics of each of the above flow rate control valves, whereby the pilot nozzle, the first main nozzle group, and the second main nozzle Fuel will be supplied to the group accurately.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-nozzle type combustor for a gas turbine according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a control system thereof.
FIG. 2 is a graph showing the control characteristics of the fuel distribution,
FIG. 3 is a graph showing the control characteristic of the fuel supply of the pilot nozzle, and FIG. 4 is a graph showing the characteristic of the valve opening correction of the pilot nozzle flow control valve.

Also in the case of the multi-nozzle type combustor for a gas turbine of this embodiment, a plurality of main nozzles 2A surrounding the pilot nozzle 1 inside the combustor inner cylinder 3 as shown in FIG. 2B are provided to share the combustion zone, and these main nozzles are divided into a first main nozzle group 2A and a second main nozzle group 2B.

In the multi-nozzle combustor for a gas turbine of this embodiment, in particular, as shown in FIG. 1, a fuel supply including a fuel distribution control circuit 6 which receives a control output signal (hereinafter referred to as CSO) from a minimum selector circuit 5. A control system is provided. The minimum selector circuit 5 selects the minimum signal as the CSO among the output signals of the control circuits for the gas turbine speed control, the maximum output limit control, the combustion gas temperature limit control, and the maximum fuel amount limit control. .

The fuel distribution control circuit 6 receives pilot nozzles CSO (PLCSO), first main nozzle group CSO (MACSO) and second main nozzle group CSO (MBCSO) from the circuit 6, respectively. 7P, the first main nozzle group fuel supply control circuit 7A and the second main nozzle group fuel control circuit 7B are connected. And these circuits 7
P, 7A and 7B are respectively through a pilot nozzle valve opening correction function circuit 8P, a first main nozzle group valve opening correction function circuit 8A and a second main nozzle group valve opening correction function circuit 8B. Pilot nozzle 1,
Flow rate control valve 9 in each fuel supply path to the first main nozzle group 2A and the second main nozzle group 2B
P, 9A and 9B are controlled.

As shown in FIG. 2, the fuel distribution control circuit 6 described above feeds fuel to the first main nozzle group 2A from the initial operation of the gas turbine multi-nozzle combustor to a predetermined first intermediate output Q1. The supply amount is gradually increased, and when the first intermediate output Q1 is reached, the fuel supply to the second main nozzle group 2B is started, and the first main nozzle group 2A is formed in proportion to the fuel supply amount to the second main nozzle group 2B. Fuel supply to the first and second main nozzle groups 2A, 2 until the maximum output is reduced.
It has an increase load control characteristic for gradually increasing each fuel supply amount to B, and at the time of reducing the load from a high load state, the first intermediate output Q2 is slightly lower than the first intermediate output Q1
And the fuel supply amount to the second main nozzle groups 2A and 2B is gradually reduced to the second intermediate output Q2 when the second intermediate output Q2 is reached.
The fuel supply amount to the main nozzle group 2B is stopped, and the fuel supply amount to the first main nozzle group 2A is increased by an amount commensurate with the fuel decrease amount when the fuel supply to the second main nozzle group 2B is stopped. The zero load control characteristic is provided to gradually reduce the fuel supply amount to the first main nozzle group 2A until zero. The fuel distribution ratio to each of the nozzles 2P, 2A, 2B is calculated so that the combustion state and NOx value are optimized depending on the rotation speed and load of the gas turbine.

The pilot nozzle fuel supply circuit 7P has a PL
When the CSO is received, the CV value is set based on the relationship between the PLCSO and the pilot nozzle flow control valve CV value shown in FIG. 3, and the control signal corresponding to the CV value is set to the pilot nozzle valve opening correction function. It is adapted to output to the circuit 8P. Note that the relationship between the PLCSO and the pilot nozzle flow control valve CV value shown in FIG. 3 is calculated by calculating the pressure loss amount in the piping of the fuel supply path to the pilot nozzle and the nozzle itself, and the CV value corresponding to each state. It was decided to become.

Pilot nozzle valve opening correction function circuit 8
When P receives a signal corresponding to the pilot nozzle flow control valve CV value from the pilot nozzle fuel supply circuit 7P, the CV value is corrected according to the correction function of the valve opening characteristic shown in FIG. Is output to the pilot nozzle flow rate control valve 9P. The correction function of the valve opening characteristic for the pilot nozzle shown in FIG. 4 is finely adjusted according to the manufacturing error of the flow control valve 9P measured in advance.

In the multi-nozzle type combustor for a gas turbine of this embodiment, a pressure control valve 10P for a pilot nozzle is further provided in the fuel flow path reaching the pilot nozzle 1, and the pilot nozzle also has a pilot nozzle 10P. Fuel supply control circuit 7
A control signal is sent from P, and the pressure control valve 10P is controlled so that the differential pressure of the flow rate control valve 9P becomes a target value.

Also for the first main nozzle group and the second main nozzle group, the fuel supply control circuits 7A and 7B, the valve opening degree correction function circuits 8A and 8B, the flow rate control valves 9A and 9B, and the pressure control. By the valves 10A and 10B, each circuit 7 for the pilot nozzle described above
Control similar to the control by P, 8P and each valve 9P, 10P is performed.

In this way, in the multi-nozzle combustor for a gas turbine of this embodiment, the fuel supply amounts to the pilot nozzle 1, the first main nozzle group 2A and the second main nozzle group 2B are used as control output signals. When the fuel supply control system that controls so as to distribute the load increases from the operating state of the predetermined first intermediate output Q1 by the pilot nozzle 1 and the first main nozzle 2A to the second main nozzle group 2B. No. 1 at the same time as the start of fuel supply
By reducing the fuel supply amount to the main nozzle group 2A, the switching control can be stably performed.

Further, when the load is sequentially reduced from the high load state, the second main nozzle group 2B is used when the load is further reduced from the predetermined second intermediate output Q2 operating state.
When the fuel supply to the first main nozzle group 2 is stopped
By increasing the amount of fuel supplied to A, the switching control can be stably performed. Since the second intermediate output Q2 is set to a lower level than the first intermediate output Q1, hysteresis is formed in the above-described fuel switching characteristic, so that the first and second intermediate outputs Q1 and Q2 are generated.
Even if a load change occurs in the vicinity of 1 and Q2, it is possible to prevent the above-mentioned hunting in which the fuel switching operation is frequently performed.

Further, the fuel supply control system is provided in each control circuit for the flow rate control valves 9P, 9A, 9B in each fuel supply path to the pilot nozzle 1, the first main nozzle group 2A and the second main nozzle group 2B. Since the valve opening correction function circuits 8P, 8A, 8B are provided, appropriate control signals can be output according to the valve characteristics of the flow rate control valves 9P, 9A, 9B. , The fuel is accurately supplied to the first main nozzle group 2A and the second main nozzle group 2B.

[0023]

As described in detail above, according to the multi-nozzle type combustor for a gas turbine of the present invention, the following effects can be obtained. (1) A fuel supply control system that controls so as to distribute each fuel supply amount to the pilot nozzle, the first main nozzle group, and the second main nozzle group according to the control output signal is based on the pilot nozzle and the first main nozzle. When increasing the load from the predetermined operating state of the first intermediate output,
At the same time when the fuel supply to the second main nozzle group is started,
By reducing the fuel supply amount to the first main nozzle group by an amount commensurate with the increase in fuel accompanying the start of supply, the switching control can be performed stably. (2) When the load is sequentially reduced from the high load state, when the load is further reduced from the predetermined second intermediate output operating state, the fuel supply to the second main nozzle group is stopped at the same time as the fuel supply is stopped. By increasing the fuel supply amount to the first main nozzle group in proportion to the accompanying fuel decrease amount, the switching control can be stably performed. (3) Since the second intermediate output is set to a lower level than the predetermined first intermediate output, a hysteresis is formed in the above-mentioned fuel switching characteristic, so that the first and second Even if a load change occurs near the intermediate output, it is possible to prevent the above-mentioned hunting in which the fuel switching operation is frequently performed. (4) The fuel supply control system includes the pilot nozzle,
When each control circuit for the flow rate adjusting valve in each fuel supply path to the first main nozzle group and the second main nozzle group is provided with a valve opening correction function circuit, Appropriate control signals are output according to the valve characteristics, so that fuel can be accurately supplied to the pilot nozzles, the first main nozzle group and the second main nozzle group. (5) From the above items (1) to (4), the control characteristics of the combined plant having a plurality of gas turbines are significantly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control system of a multi-nozzle type combustor for a gas turbine as one embodiment of the present invention.

2 is a graph showing control characteristics for fuel distribution in the combustor of FIG. 1. FIG.

3 is a graph showing control characteristics for fuel supply of a pilot nozzle in the combustor of FIG.

FIG. 4 is a graph showing the characteristics of valve opening correction of the pilot nozzle flow control valve in the combustor of FIG. 1.

FIG. 5 is a front view of a multi-nozzle type combustor for a gas turbine.

[Explanation of symbols]

 1 Pilot Nozzle 2A First Main Nozzle Group 2B Second Main Nozzle Group 3 Combustor Inner Cylinder 4 Swirler 5 Minimum Selector Circuit 6 Fuel Distribution Control Circuit 7A First Main Nozzle Group Fuel Supply Control Circuit 7B Second Main Nozzle Group Fuel Supply Control Circuit 7P Pilot nozzle fuel supply control circuit 8A First main nozzle valve opening correction function circuit 8B Second main nozzle valve opening correction function circuit 8P Pilot nozzle valve opening correction function circuit 9A First main nozzle flow rate adjustment Valve 9B Flow control valve for second main nozzle 9P Flow control valve for pilot nozzle 10A Pressure control valve for first main nozzle 10B Pressure control valve for second main nozzle 10P Pressure control valve for pilot nozzle

Claims (2)

[Claims] 1. A multi-nozzle type combustor for a gas turbine, comprising: a pilot nozzle; and a first main nozzle group and a second main nozzle group, each of which comprises a plurality of main nozzles installed near the pilot nozzle, A fuel supply control system for controlling the fuel supply amounts to the pilot nozzles, the first main nozzle group, and the second main nozzle group to be distributed according to a control output signal is provided, and the control system controls the combustion. From the initial operation of the reactor to the predetermined first intermediate output, the fuel supply amount to the first main nozzle group is gradually increased to
When the intermediate output is reached, fuel supply to the second main nozzle group is started, and the fuel supply amount to the first main nozzle group is reduced by an amount commensurate with the fuel supply amount to the second main nozzle group. Up to the maximum output, it has an increase load control characteristic that gradually increases the fuel supply amount to the first and second main nozzle groups, and
When the load is decreased from the high load state, the first and second intermediate outputs up to a predetermined second intermediate output slightly lower than the first intermediate output are provided.
Each fuel supply amount to the main nozzle group is gradually reduced, and when the second intermediate output is reached, the fuel supply amount to the second main nozzle group is stopped and the fuel supply amount to the second main nozzle group is stopped. It is characterized in that the fuel supply amount to the first main nozzle group is increased by an amount commensurate with the fuel reduction amount, and then the fuel supply amount to the first main nozzle group is gradually reduced until the output reaches zero. A multi-nozzle type combustor for gas turbines. 2. The multi-nozzle combustor for a gas turbine according to claim 1, wherein the fuel supply control system includes a fuel distribution control circuit for receiving the control output signal, the pilot nozzle and the first main nozzle group. And each fuel supply control circuit for the flow rate control valve in each fuel supply path to the second main nozzle group is connected,
A multi-nozzle combustor for a gas turbine, characterized in that a valve opening correction function circuit is connected to the fuel supply control circuit.