JPH05248269A - Combustion control method for gas fuel - Google Patents

Abstract

PURPOSE:To prevent abnormal combustion of explosion or the like at the time of ignition by detecting leakage of gas fuel before starting a combustor, and interlocking starting of the combustor. CONSTITUTION:A combustion control method provides a control system such that a change of pressure of gas fuel, sealed between a fuel passage 1 and a branch fuel passage 1a reaching a main shutoff valve 4 and a primary shutoff valve 5 from safety shutoff valves 2, 3, is detected by a pressure switch 7, to interlock starting a combustor 6 by receiving a signal from a control part 8 of this pressure switch. In this way, abnormal combustion at ignition time in the combustor can be prevented thus to display an effect of eliminating damage of the combustor itself further of a duct or the like in a rear part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling combustion of gas fuel in a gas turbine or the like.

[0002]

2. Description of the Related Art Generally, when a gas fuel combustor is started, pre-purge is performed before main combustion. It is recommended to attach various safety devices to the control device around the combustor.

As such a combustion control apparatus for gas fuel, a safety cutoff valve 2, 3, a main cutoff valve 4, a flow control valve 10, a pressure are provided in a fuel passage 1 communicating with an inlet of a combustor 6 as shown in FIG. The switch 7 and the control unit 8 connected to the switch 7 are also connected to the branch fuel passage 1a which branches off from the main passage valve 4 in the fuel passage 1 and leads to the inlet of the combustor 6, the primary cutoff valve 5 and the throttle valve. There is known a gas turbine device provided with an engine control box 9 for controlling the operation of each of the above-mentioned equipments. However, in this device, the pressure of the gas fuel supplied to the combustor 6 during the combustion after the start is measured by the pressure switch 7, and when the pressure value is out of the control range, the control section 8 causes the engine to operate. An alarm signal is issued to the control box 9, and in response to this, an operation closing signal, that is, a command signal for closing each shutoff valve is issued from the engine control box 9 to the safety shutoff valves 2 and 3 and the main shutoff valve 4. Only a control system was installed to shut off the supply of gas fuel to the combustor. Therefore, if the gas fuel leaks from the main shut-off valve 4 and enters the combustor 6 at the time of starting the combustor, that is, at the time of ignition, abnormal combustion such as explosion occurs in the combustor 6, and the combustor itself and further Sometimes the rear ducts were damaged.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above technical problems, detects gas fuel leakage in the pre-start process of the combustor, and prevents abnormal combustion such as explosion in the combustor at the start. An object of the present invention is to provide a combustion control method for gas fuel.

[0005]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the utilization of the above-mentioned conventional pressure switch and its control unit. Before starting the combustor, the gas fuel from the primary shutoff valve and the main shutoff valve is used. The leak is detected by the pressure switch, and the combustor start can be interlocked by an alarm signal from the control unit.

That is, according to the present invention, a safety cutoff valve, a main cutoff valve, a primary cutoff valve, a pressure switch and its control unit, and a control system by an engine control box for controlling the operation of each of the above devices are provided in the fuel passage leading to the combustor inlet. In the provided gas fuel combustion control device, gas fuel is sealed in the fuel passage leading to the safety cutoff valve and the main and primary cutoff valves before the start of the combustor, and a pressure change signal from the control unit of the pressure switch is transmitted. A control system, which is transmitted to the engine control box to interlock the start of the combustor, is coupled to the control system.

[0007]

According to the present invention, in the pre-purge of the combustor, the leakage of the gas fuel from the primary shut-off valve and the main shut-off valve is detected, and when the leak is recognized, the supply of the gas fuel to the combustor is shut off. At the same time, since the start of the combustor is interlocked, it is possible to prevent abnormal combustion such as explosion in the combustor due to gas fuel leakage.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a gas fuel combustion control device in a gas turbine, and FIG. 2 is a block diagram showing a control system of the combustion control device of FIG. In FIG.
The safety cutoff valves 2, 3, the pressure switch 7, the main cutoff valve 4, and the flow control valve 10 are connected in series to the fuel passage 1 from a fuel tank or the like (not shown) to the inlet of the turbine combustor 6, and Main shutoff valve 4 in fuel passage 1
A primary cutoff valve 5 and a throttle 11 are arranged in a branched fuel passage 1a that branches from the front side of the branch fuel passage 1a to the inlet of the combustor 6. Further, a control system is provided for connecting the above-mentioned devices to the engine control box 9 and controlling the operation of these devices.

The operation of this apparatus in the pre-start process of the gas turbine combustor will be described. First, the safety shutoff valves 2 and 3 are opened to supply the gas fuel to the fuel passage 1. At this time, since the main shutoff valve 4 and the primary shutoff valve 5 are closed, the fuel passages 1 and 1a extending from the safety shutoff valve 3 to the main and primary shutoff valves 4 and 5, respectively.
Is filled with gas fuel, and then the safety shutoff valves 2, 3
The valve is closed to fill the gas fuel between the fuel passages. Then, the pressure switch 7 measures the pressure change of the enclosed gas fuel for a certain period of time to detect the gas fuel leak. These operation timings use the timing signal of the pre-purge process that is normally performed.
A control unit 8 for transmitting a signal to the engine control box 9 is connected to the pressure switch 7, and when the measured value of the gas fuel pressure is equal to or lower than a preset lower limit value, the control unit 8 is connected. Sends a gas fuel pressure drop signal from the engine control box 9 to the engine control box 9 and fixes the safety shutoff valves 2, 3, the main shutoff valve 4, and the primary shutoff valve 5 to the closed state. In addition to issuing a command signal that causes the combustor 6 to be released, a control system that interlocks the combustor 6 so that it is not started is formed. Therefore, when the control unit 8 of the pressure switch 7 detects the pressure decrease in the fuel passage 1 in which the gas fuel is sealed, that is, the leakage of the gas fuel is detected before the prepurging, the combustor 6 is not prepurged. The abnormal combustion in the combustor 6 can be prevented. Further, in the same manner as in the conventional example, the engine control box 9 issues the command signal to stop the operation of the combustor when the gas fuel pressure in the fuel passage 1 changes after the gas turbine is started. There is a control system for

FIG. 2 is a block diagram showing the input / output relationship of signals in the control system of the present invention. The engine control box 9 is connected to a serious failure signal transmission system 13 and an operation / stop command system for a gas turbine. The signal input system from 14 and the starter motor 1 receiving the above signal input
2 is a signal output system for operating and stopping the main and primary shutoff valves 4 and 5, and opening and closing the safety shutoff valves 2 and 3, and a gas turbine rotation speed signal 15 for the gas turbine. Start / stop command system 14
A signal output system for feedback to is connected.
The present invention is characterized by the safety shutoff valves 2 and 3 which have been conventionally closed in the pre-purge which is a pre-start process.
Open and then close again to set pressure switch 7
The gas fuel is sealed in a fuel passage having a certain pressure, and the gas fuel pressure change signal from the control unit 8 of the pressure switch 7 at that time is sequentially transmitted to the serious failure signal transmission system 13 and the engine control box 9 to receive this signal. A command signal from the engine control box 9 fixes each of the safety shutoff valves 2, 3, the main shutoff valve 4, and the primary shutoff valve 5 to the closed state, and the gas turbine operation stop command system 1
4 is a point in which a control system for releasing the operation command of No. 4 and interlocking so as not to start the combustor 6 is formed. According to the present invention, when a change in the gas fuel pressure in the fuel passage 1 after the start of the gas turbine is detected, a serious failure signal from the control unit 8 of the pressure switch 7 is received and output from the engine control box 9 as in the conventional case. The safety valves 2 and 3 and the main shutoff valve 4 are controlled to be closed by a command signal.

[0011]

According to the present invention, in the pre-purge which is the pre-starting step of the gas turbine combustor, the leakage of gas fuel from the primary shutoff valve and the main shutoff valve is transmitted to the engine control box as a gas fuel pressure change signal. In response to this signal, the engine control box forms a control system that interlocks the start of the combustor, so it is possible to prevent abnormal combustion such as explosion in the combustor due to the gas fuel leak, and the combustor itself. Further, the rear duct and the like are not damaged.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a gas fuel combustion control device in a gas turbine.

FIG. 2 is a block diagram showing a control system of an embodiment of the present invention in the combustion control system of FIG.

[Explanation of symbols]

 1 Fuel passage 2, 3 Safety cutoff valve 4 Main cutoff valve 5 Primary cutoff valve 6 Combustor 7 Pressure switch 8 Controller 9 Engine control box 10 Flow control valve 11 Throttle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F23N 5/24 102 A

Claims (1)

[Claims] 1. A safety cutoff valve, a main cutoff valve, a primary cutoff valve, a pressure switch and its control unit, and a control system connected to an engine control box for controlling the operation of each of the above devices are provided in a fuel passage leading to the combustor inlet. In a gas fuel combustion control method, gas fuel is sealed in a fuel passage leading to the safety cutoff valve and the main and primary cutoff valves before starting of a combustor, and a pressure change signal from a control unit of the pressure switch is sent to the engine. A combustion control method for gas fuel, characterized in that a control system for transmitting a control box to interlock the start of the combustor is connected to the control system.