JPS5849684B2 - gas turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas turbine-steam turbine complex plant control method and apparatus, and particularly to a plant control method when fuel supply to a gas turbine in the plant is suddenly cut off due to an accident or other cause. and a control device for implementing the method.

Recently, in Japan and the United States, plans are underway to construct a combined power plant using a gas turbine and a steam turbine as power sources.

This power plant includes several gas turbines, several generators driven by the gas turbines, several boilers operated by the exhaust gas from the gas turbines, and several generators driven by the gas turbines, and several boilers driven by the exhaust gas from the boilers. A steam turbine power generation plant includes a single steam turbine driven by generated steam and a generator driven by the steam turbine.

In this complex plant, the flexibility of the entire plant can be increased by using a gas turbine capable of rapid startup in conjunction with a steam turbine during startup and peak load times. By operating the boiler using exhaust heat, there is an advantage that the thermal efficiency of the entire plant can be improved.

However, in this type of plant, various problems remain to be solved in order to match the three types of power generating devices: a gas turbine, a boiler, and a steam turbine.

One such problem is to establish effective measures to prevent the effects of this accident from affecting the steam turbine in the event that an accident occurs in which the fuel supply to a gas turbine is suddenly cut off. This can be mentioned.

An object of the present invention is to provide a control method for preventing serious adverse effects on the operation of a steam turbine and the complex plant in the event of an accident as described above, and a control device for implementing this control method. It is.

The present invention will be described below with reference to the accompanying drawings,
In order to better understand the present invention, prior to explaining the present invention, the general structure of a known gas turbine-steam turbine combined plant will first be explained with reference to FIG.

In FIG. 1, reference numeral 1 indicates a compressor of a gas turbine included in a gas turbine power generation plant, and air compressed by this compressor 1 is supplied to a combustor 2, where it is The supplied fuel f is combusted.

Combustion gas generated in the combustor 2 is supplied to a power turbine 3, and the power turbine 3 is connected to a generator 4.
Rotate.

(Several gas turbine power generation units consisting of a combination of a gas turbine and a generator are arranged for a single steam turbine that will be explained later, but in Figure 1, only the single gas turbine power generation unit is shown. Illustrated.

) A boiler 5 is connected to each gas turbine power generation unit, and a gas introduction pipe 6 for guiding combustion gas from the power turbine 3 is connected to the boiler 5.

The number of boilers 5 is the same as that of each cast turbine power generation unit, and this group of boilers constitutes a steam turbine power generation plant together with a single steam turbine to be described later.

A gas inlet pipe 6 to the boiler 5 is provided with an inlet gas damper 7, and a bypass pipe 8 branched from the gas inlet pipe 6 is provided at a position upstream of the inlet gas damper 7.

The bypass pipe 8 is connected to a gas discharge pipe 9 from the boiler 5, and the bypass pipe 8 is provided with a bypass valve 10.

The outlet steam pipe 11 of each boiler 5 is connected to a single steam header 13 via a boiler outlet valve 12, and the outlet steam pipe 11 is connected to a steam bypass pipe 14 at a position upstream of the boiler outlet valve 12. is connected to the branch.

The steam bypass pipe 14 is connected to the condenser 15 and the pipe 14
A bypass valve 16 is provided in the middle.

The steam header 13 is connected to a single steam turbine 18 via a main steam pipe 17, and a known control valve 19 is provided in the middle of the main steam pipe 17.

A large-capacity generator 20 is connected to the steam turbine 18,
This generator generates most of the electrical power generated in the complex plant.

If an accident occurs in which the supply of fuel to the gas turbine combustor 2 of one gas turbine power generation unit is suddenly cut off in the complex plant configured as described above, the boiler 5 connected to the gas turbine power generation unit The temperature of the combustion gas supplied to the boiler decreases rapidly, which lowers the temperature of the boiler, and the temperature of the steam generated from the boiler decreases so that it is no longer temperature consistent with the steam generated from other boilers. A situation may arise where it becomes impossible to do so.

Due to this situation, the steam conditions of the steam supplied to the steam turbine fluctuate, which adversely affects the operation of the steam turbine.

Furthermore, if the plant continues to operate without noticing the cutoff of fuel supply to the cast turbine, the boiler temperature will drop and it will take a considerable amount of time to raise the boiler temperature again. It will also be necessary.

Therefore, the main object of the present invention is to provide a control method for preventing serious hindrance to the operation of a steam turbine and the complex plant in the event of an accident as described above, and a method for implementing the control method. The purpose of the present invention is to provide a control device.

FIG. 2 of the accompanying drawings is a schematic diagram showing the configuration of a control device for implementing the method of the present invention.

What is indicated by the reference numeral 21 in the figure is a flame detector for detecting the cutoff of the supply of fuel f to the gas turbine combustor 2, and the signal generated by this flame detector 21 is A known turbine control device 2 that controls the operation of
2, a control device 23 that opens and closes the bypass gas damper 10 and inlet gas damper 7 of the boiler, and a valve control device 24.

Valve controller 24 is in communication with boiler outlet steam valve controller 25, the former outputting a control signal commanding the latter to close boiler outlet steam valve 12.

A sample hold circuit 26 is connected to the boiler outlet valve control device 25, and this sample hold circuit 26 is activated when an input is received from the boiler outlet valve control device 25. It has a function of sampling the pressure detection signal and temporarily holding the detected value in the circuit.

A pressure detection signal from a pressure gauge 29 attached to the boiler outlet steam pipe 11 is input to a comparison circuit 28 connected to the output side of the sample and hold circuit 26 .
is the input signal from the sample hold circuit 26 and the pressure gauge 2
The magnitudes of the pressure detection signals from 9 are compared, and an output signal having a magnitude equal to the deviation between both signals is output to the bypass valve control device 30.

In this configuration, after a predetermined time delay from when the sample hold circuit 26 first detects the steam pressure in the steam header 13 when a gas turbine fuel cut-off accident occurs, the comparator circuit 28 supplies the signal to the bypass valve control device 30. A deviation signal between the steam header internal pressure and the boiler outlet steam pipe pressure is output.

In such a configuration, the damper control device 23 can have a configuration as shown in FIG. 3, for example.

In FIG. 3, a flame detector 21 is installed in the damper control device 23.
a relay switch 231 that is energized and closed by a flame extinguishment detection signal from the relay switch 231; a bypass damper control device 233 to which the drive power source 232 is connected when the relay switch 231 is closed; and the bypass damper control device 2.
Another relay switch 234 that is closed by the output from 3&, and an inlet damper control device 235 to which the drive power source 232 is connected when the relay switch 234 is closed.
and are included.

The bypass damper control device 233 controls the bypass damper 10 on the boiler population side, and the inlet damper control device 235 controls the inlet damper 7 on the boiler population side.

It will be understood that according to the configuration shown in FIG. 3, when the flame extinguishment detection signal is generated from the flame detector 21, the bypass tamper 10 and the inlet gas damper 7 are sequentially closed.

Figure 4 shows the sampling and hold circuit 2 shown in Figure 2.
6 is a schematic diagram of a control system including 6.

For example, as shown in FIG. 4, the sampling hold circuit 26 includes a relay switch 261 that is closed by the output from the boiler outlet valve control device 25 and a hold circuit 262, and the output from the boiler outlet valve control device 25 is input. It is configured such that the detected value of the pressure inside the steam header 13 is input to the hold circuit 262 when the steam header 13 is turned on.

In such a configuration, when the detector 21 generates a signal indicating flame extinguishment in the combustor 2, the boiler outlet valve 12 is closed by the boiler outlet valve control device 25 in response to the signal, and at the same time, the boiler outlet valve 12 is closed by the boiler outlet valve control device 25. A sample and hold circuit 26 is activated by the output from the sample and hold circuit 25, and the output from the sample and hold circuit 26 is inputted to a comparator 28.

When the comparator 28 receives an input from the sample hold circuit 26, it compares this input value with the output value of the pressure gauge 29 provided in the boiler outlet steam pipe 11, and generates an output signal with a magnitude equal to the difference between the two. is output to the bypass valve control device 30.

When this input is received, the bypass valve control device 30 controls the opening degree of the bypass valve 16 according to the magnitude of this input signal.

Now, from the above description, it will be understood that the control device of the present invention operates as follows when the fuel supply to the gas turbine is cut off.

In Fig. 2, when a sudden cutoff of fuel supply to the gas turbine occurs in one of the gas turbine power generation units that make up the gas turbine power generation plant, the gas turbine power generation unit installed in the gas turbine combustor 2 An output is generated from the flame detector 21 in which the gas turbine controller 22
The gas turbine is shut down.

At the same time, the damper control device 23 first opens the bypass damper 10, and then closes the boiler artificial gas damper 7.

The boiler outlet valve 1 is activated simultaneously with the operation of the damper control device 23.
2 and bypass valve 16 is activated, first the boiler outlet valve control device 25 closes the boiler Yamaguchi valve 12, and then the output from the boiler outlet valve control device 25 closes the sample hold circuit 26. is activated.

Therefore, the sample and hold circuit 26 inputs the detected pressure value in the steam header 13 into the hold circuit 262, and the output of the hold circuit 262 corresponds to the minimum pressure among the pressure distributions in the steam header 13. is output to the comparison circuit 28.

The comparison circuit 28 outputs an output equal to the deviation between the input value from the sample and hold circuit 26 and the detected pressure value of the boiler outlet pipe 11 to the bypass valve control device 30, and the bypass valve control device 30 determines the magnitude of the input to the device. The opening degree of the bypass valve 16 is controlled accordingly.

Therefore, if the supply of fuel to a gas turbine is suddenly cut off, the supply of combustion gas to the boiler connected to the gas turbine is immediately stopped, and at the same time the boiler outlet valve is closed, reducing the heat capacity of the boiler. The opening degree of the bypass valve 16 is controlled so that the steam pressure in the boiler does not rise above the allowable limit due to the residual heat in the boiler, so that the steam pressure in the boiler remains constant. It is maintained above the limit.

Furthermore, according to the present invention, even in the event of an accident in which the gas turbine suddenly trips in a gas turbine-steam turbine complex plant, the steam conditions of the steam supplied to the steam turbine will not be drastically changed. , it is possible to prevent adverse effects on the steam turbine.

As a result, even when a sudden load is placed on this plant, the boiler can be heated up immediately.
This makes it possible to ensure the stability of plant operations.

Those skilled in the art will readily understand that the accompanying drawings and the foregoing description thereof are merely illustrative of one embodiment of the present invention, and that the present invention can be modified in various ways within the scope of the claims. By the way.

For example, in the embodiment described above, the cutoff of the fuel supply to the gas turbine is detected by a flame detector, but it goes without saying that this detection may be carried out by other means.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a known ω gas turbine-steam turbine combined plant to which the present invention is applied, FIG. 2 is a schematic diagram showing the overall configuration of a control device according to the present invention in the form of a program diagram, and FIGS. The figure is a schematic diagram showing an embodiment of a portion of the apparatus shown in FIG. 2. Explanation of symbols, 22...Gas turbine control device,
23... Damper control device, 24...
Valve control device, 25... Boiler output valve control device, 26... Sample hold circuit, 28...
... Comparison circuit, 30 ... Bypass valve control device.

Claims (1)

[Scope of Claims] 1. A gas turbine power generation plant including a plurality of gas turbines and a plurality of generators driven by the gas turbines, and a plurality of boilers operated by exhaust heat from the gas turbines. In a gas turbine-steam turbine combined plant comprising a steam turbine power plant that includes a steam turbine driven by the steam generated from the boiler and a generator driven by the steam turbine, When the supply of fuel to the gas turbine is suddenly cut off, the cutoff of the fuel supply to the combustor of the gas turbine is detected, the gas turbine is stopped in response to this fuel cutoff detection signal, and the gas turbine is stopped. fully open a bypass gas damper at the inlet of a boiler connected to the boiler, simultaneously close an inlet gas damper at the inlet of the boiler to cut off the supply of exhaust gas from the gas turbine to the boiler, and then close the outlet valve of the boiler. After that, the outlet side bypass valve on the outlet side of the boiler is opened so that the steam pressure inside the steam head that receives steam from each boiler of the steam turbine power generation plant is equal to the steam pressure inside the boiler. 1. A method for controlling a gas turbine-steam turbine complex plant, characterized in that the temperature is controlled. 2 At the same time as closing the boiler Yamaguchi valve, the pressure in the steam header is sampled and this detected value is temporarily held, and then the held detected value is compared with the pressure detected in the outlet pipe of the boiler and both are determined. 2. The method of controlling a gas turbine-steam turbine complex plant according to claim 1, wherein the bypass valve is controlled in accordance with a deviation of the detected value. 3. A gas turbine power generation plant including a plurality of gas turbines and a plurality of generators driven by the gas turbines, a plurality of boilers operated by exhaust heat from the gas turbines, and steam generated from the boilers. a steam turbine power generation plant including a steam turbine driven by a steam turbine and a generator driven by the steam turbine; a gas turbine controller that is activated in response to an output signal of the detector; a damper controller that opens a bypass gas damper and subsequently closes the inlet gas damper in response to the signal; a valve control device that is operated in response to the signal; and a control signal that closes the boiler Yamaguchi valve in accordance with the output from the valve control device and simultaneously outputs a control signal that causes the steam pressure in the steam header to be sampled. A boiler Yamaguchi valve control device, a sampling hold circuit that is operated by a control signal from the boiler exit valve control device and holds a detected value of steam pressure in the steam header, and a magnitude of an output signal from the sampling hold circuit. and a comparison circuit that compares the magnitude of the steam pressure detection signal in the boiler outlet steam pipe with the magnitude of the steam pressure detection signal in the boiler outlet steam pipe and generates an output equal to the deviation of both signals, and the opening degree of the bypass valve is adjusted depending on the magnitude of the output from the comparison circuit. A control device for carrying out the method according to claim 1, comprising a bypass valve control device for controlling.