JP2656352B2 - Coal gasification power plant - Google Patents

Description

The present invention relates to a coal gasification power generation plant, and more particularly to a coal gasification power generation plant whose operation is stabilized by improving a plant control device. .

(Prior art) A coal gasification power generation plant turns coal into gaseous fuel, and uses the gas as a working fluid source to rotationally drive a gas turbine and a compressor, and also to rotationally drive a generator, which makes effective use of energy. , Attention has been paid to the superiority of pollution issues.

Among the power plants, the integrated coal gasification combined cycle power plant leads the exhaust heat of the gas turbine to the boiler, and the steam obtained by heat exchange by the exhaust heat and the steam obtained by the heat exchanger (cooler) of the gasification furnace. Are conducted to a steam turbine to generate power, and have a great feature that the heat recovery capability is extremely high.

FIG. 2 is a schematic system diagram showing such an integrated coal gasification combined cycle power plant system.

Coal is sent to a gasification furnace 1 for producing a crude gas through a coal amount adjusting device 2 and an oxidant such as air is sent through an oxidant amount adjusting device 3.

The crude gas produced in the gasification furnace 1 is sent to a gas purifier 5 via a gas cooler 4, where the fuel gas is refined. The fuel gas is sent to the combustor 8 via the fuel pressure regulating valve 6 and the fuel flow regulating valve 7, and is burned by the air pressurized by the compressor 9. The gas turbine 10 is driven by the combustion gas, and power is generated by the generator 11. The air pressurized by the compressor 9 is further pressurized by the pressurized compressor 12 driven by the electric motor 13 and supplied to the oxidizing agent flow control device 3.

On the other hand, after driving the gas turbine 10, the combustion gas is sent to the exhaust heat recovery boiler 15 as exhaust gas of the gas turbine 10. The exhaust heat recovery boiler 15 has a super heater 16, an evaporator 17, and an economizer 18 in order from the upstream with respect to the flow of the exhaust gas, where heat energy of the exhaust gas is recovered, and steam is generated by these heat exchangers. Occur. That is, a part of the supply water heated by the economizer 18 is sent to the gas cooler drum 14, and the rest is sent to the steam drum 19. The feedwater sent to the gas cooler drum 14 circulates through the gas cooler 4 to the gas cooler drum 14,
The steam generated during this time is sent from the gas cooler drum 14 to the super heater 16. The feed water sent to the steam drum 19 is returned to the steam drum 19 again via the evaporator 17,
The steam generated during this time is also sent to the superheater 16.

The dry steam generated by the superheater 16 is sent to a steam turbine 21 via a steam control valve 20, and is used for driving a generator 22, that is, power generation. The steam that has lost energy by driving the steam turbine 21 is sent to a condenser 23 where indirect heat exchange is performed with the cooling water, where the steam is returned to water at almost normal temperature. This water is sent to the economizer 18 via the feed water heater 24 and the deaerator 25, and is again vaporized.

By the way, as is well known in the operation of the entire plant, a gas turbine following mode and a gasifier following mode are performed, and any one of these modes is selected according to the purpose.

In the gas turbine follow-up mode, the gasification furnace equipment including the gasification furnace 1, the coal amount adjusting device 2, the oxidizing agent amount adjusting device 3 and the like performs load control, and the combustor 8, the compressor 9, the gas turbine 10, the electricity generation 11, fuel pressure control valve 6, fuel flow control valve 7
This is a mode in which the gas turbine equipment configured as described above controls the gas pressure at the gas turbine inlet (or the gas pressure at the gas purification equipment inlet).

The gasification furnace follow-up mode is a mode in which the gas turbine equipment controls the load and the gasification equipment controls the gas pressure at the gas turbine inlet.

Generally, the gasification furnace follow-up mode has an advantage that power generation can be performed without a large delay with respect to a required power generation amount. However, since the gas pressure supplied from the gasification furnace 1 is accompanied by a large delay, There is a disadvantage that the gas pressure fluctuates greatly when the load changes.

On the other hand, the gas turbine follow-up mode has the advantage of maintaining a stable state without a large change in the gas pressure even when the load changes, etc. There is a drawback that when the load changes, the control is greatly delayed because it changes with the delay.

That is, there is an advantage in the gasifier follow-up mode from the viewpoint of load demand, and there is an advantage in the gas turbine follow-up mode from the viewpoint of stable operation of the system, that is, prevention of equipment consumption.

The coal gasification power plant has a gasifier temperature of 1400 ~
Since the temperature is as high as 1600 ° C., general metal materials cannot cope with the problem, and bricks and the like are used. However, sudden changes in the furnace environment such as the furnace temperature accelerate the consumption of bricks. However, as the operation mode, the operation in the gas turbine following mode is often used in order to operate the system more stably.

FIG. 3 shows an example of a conventional control circuit in a gas turbine following mode.

FIG. 1 shows a gasifier facility including a gasifier 1, a coal amount controller 2 and an oxidizer amount controller 3, a combustor 8, a compressor 9, a gas turbine 10, a power generator 11, and a fuel pressure control valve 6. And a gas turbine facility comprising a fuel flow control valve 7.

A generator output detector 26 of the generator 11 of the gas turbine equipment is provided, an inlet pressure detector 27 is provided upstream of the fuel pressure regulating valve 6, and an inlet pressure detector is provided upstream of the fuel flow regulating valve 7. A vessel 28 is provided. Detection signals from the generator output detector 26 and the inlet pressure detectors 27 and 28
101, 102, and 103 are input to the plant control device 29, respectively.

The plant control device 29 includes a gasification furnace control unit 30, a gas turbine control unit 31, a load control unit 32, and a pressure control unit 33.

In the load control unit 32, a load setting signal 104 is output from the load setting device 36 operated by the increasing operation device 34 or the decreasing operation device 35, and is input to the load change rate limiter 37. In the load change rate limiter 37, after the load setting signal 104 is increased or decreased by a value of a change rate selected in advance, the output signal 1
Output as 05. Then, the output signal 105 and the output signal 101 of the generator output detector 26 input to the plant control device 29 are subjected to subtraction processing in the subtractor 38, and the obtained deviation signal 106 is input to the proportional integration element 39. Then, a proportional integral calculation is performed. The value after the proportional integration process is input to the gasifier control unit 30 as a gasifier control command signal 107, and based on the gasifier control command signal 107, the input amounts of the coal and the oxidizer are controlled and calculated, Thereafter, it is output as a control command signal 108 of the coal amount adjusting device 2 and a control command signal 109 of the oxidizing agent amount adjusting device 3.

On the other hand, in the pressure control unit 33, the increasing operation device 40 or the decreasing operation device
Pressure setting signal 11 from pressure setter 42 operated by 41
0 is output and input to the pressure change rate limiter 43. In the pressure change rate limiter 43, after the pressure setting signal 110 is increased or decreased by a value of the change rate set in advance, it is output as an output signal 111. And this output signal 111,
The output signal 102 from the inlet pressure detector 27 of the fuel pressure control valve 6 input to the plant control device 29 is subjected to subtraction processing in the subtractor 44, and the deviation signal 112 obtained here is input to the proportional integration element 45. Then, a proportional integral calculation is performed. The value after the proportional integration process is input to the gas turbine control unit 31 as a gas turbine control command signal 113. After the fuel gas flow rate is control-calculated based on the gas turbine control command signal 113, the value is supplied to the fuel flow control valve 7. It is output as a control command signal 114.

The signal 103 from the gas inlet pressure detector 28 of the fuel flow control valve 7 is input to the gas turbine controller 31. The control signal 115 is output to the fuel pressure regulating valve 6 based on the calculation result in the gas turbine control unit 31, and the control signal 115 causes the fuel pressure regulating valve 6 to always keep the gas inlet pressure of the fuel flow regulating valve 7 constant. It is controlled so that the fuel is cut off suddenly in the event of an abnormality or the like.

With the configuration of the plant control device 29 described above, the gasifier facility performs load control, and the gas turbine facility performs pressure control, so that the required load can be obtained and the gas system pressure can be set to a desired value. Become.

(Problems to be Solved by the Invention) In recent years, regarding the upper limit value of the gas turbine inlet temperature, the cooling technology of turbine blades and combustors has been remarkably improved. As turbine blades and combustors made of ceramics are being developed, the turbine inlet temperature design rated point is expected to increase further in the future. Especially in a coal gasification power plant, when using a gas turbine operated at a gas turbine inlet temperature of about 1300 ° C and performing combined power generation with a steam turbine, a steam turbine or higher thermal efficiency can be obtained. According to the trial calculation, regarding the increase of the gas turbine inlet temperature,
It is also of particular interest.

However, as is well known, gas turbine equipment has a compressor 9.
When the suction flow rate in the fuel cell is constant, the generator output obtained with an increase in the fuel input increases and the combustor 8
The internal temperature increases. Therefore, in response to a demand for increasing the fuel that deviates from the temperature at the design point, the increase in the fuel must be limited in order to protect the gas turbine. It is provided in 31.

Generally, a gas turbine for power generation is designed so that a rated load can be obtained at an ambient temperature of 15 ° C. and a gas turbine inlet temperature at a rated point temperature. Therefore, when the atmospheric temperature rises, such as in summer, the density of the air becomes lighter, and the volume flow rate of the air absorbed from the atmosphere by the gas turbine is constant, so the mass flow rate of the air decreases. . For this reason,
If the gas turbine inlet temperature is operated at the design point temperature, the amount of generated power obtained will be lower than the rated point. Therefore, when the load request signal when the atmospheric temperature rises is the rated point, the gas turbine control unit 31 operates the fuel flow control valve 7 based on the signal from the pressure control unit 33 to obtain the rated point gas flow rate. Although the opening operation is performed, when the gas turbine inlet temperature reaches the rated point, the valve opening of the fuel flow control valve 7 is limited by a limit control system (not shown) so that the fuel is not further increased. The gas turbine is designed to operate safely.

However, the restriction control operation of the gas turbine controller 31 in the coal gasification power plant is based on the gas turbine controller.
This means non-selection of the control command signal 113 to 31. That is, in the gas turbine following mode, the generated gas pressure and in the gasification furnace following mode, the generated power are each in a control non-selection state. In particular, in the gas turbine following mode, the generated gas pressure is not controlled, and as a result, the gas pressure rises or falls, and the stable operation of the system, which is the operation purpose of the present operation mode, is not performed.

The present invention has been made in view of such circumstances, and provides a coal gasification power generation plant capable of operating a stable system without abnormal fluctuation of generated gas pressure even during gas turbine limit control. It is.

[Configuration of the invention]

(Means for Solving the Problems) The present invention uses gasifier equipment for gasifying coal, gas turbine equipment using coal gas generated by the gasifier as fuel, and heat generated by gas turbine exhaust gas. In a coal gasification and power generation plant having a steam turbine facility, a generator provided in each of the turbine facilities, and a plant control device for controlling the gasification furnace facility and the gas turbine facility, the plant control apparatus includes a gasifier A pressure control unit that sets a gas pressure to a required value based on a detected value of a gas pressure supplied from a gas turbine control unit that controls the gas turbine equipment based on an output signal from the pressure control unit, A load control unit for detecting an output of the generator and setting the output to a required value; and controlling the gasification furnace equipment based on an output signal from the load control unit. A gasifier control unit to be controlled, a switch for taking out a deviation signal in the pressure control unit when the gas turbine equipment is not selected for gas turbine pressure control in a gas turbine following mode, and refer to the deviation signal. A function generator that is input as a signal and sets a reduced load according to the magnitude of the pressure deviation; and a changer setter that increases or decreases the load set value of the load controller based on the output signal of the function generator. And characterized in that:

(Operation) According to the present invention, when the coal gasification power generation plant is operated in the gas turbine following mode, when the gas turbine control unit is in the limit control state, the pressure deviation in the pressure control unit in the switching unit. A signal is selected and a run-back (pull-back) operation is performed to increase or decrease the load set value based on the magnitude of the pressure deviation.

Therefore, the load acts so as to automatically obtain a desired fuel gas pressure.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

The integrated coal gasification combined cycle power plant to be controlled in the present embodiment is the same as that shown in FIG. 2, so that FIG. 2 is used as it is for the description of the present embodiment.

FIG. 1 shows a gasifier facility including a gasifier 1, a coal amount adjusting device 2, and an oxidizing agent amount adjusting device 3, a combustor 8, a compressor 9, a gas turbine 10, a generator 11, and a fuel pressure adjusting valve 6. And a gas turbine facility comprising a fuel flow control valve 7.

A generator output detector 26 of the generator 11 of the gas turbine equipment is provided, an inlet pressure detector 27 is provided upstream of the fuel pressure regulating valve 6, and an inlet pressure detector is provided upstream of the fuel flow regulating valve 7. A vessel 28 is provided. Detection signals from the generator output detector 26 and the inlet pressure detectors 27 and 28
201, 202, and 203 are input to the plant control device 63, respectively.

The plant control device 63 includes a gasifier control unit 64, a gas turbine control unit 65, a load control unit 66, and a pressure control unit 67.

In the load control unit 66, the load setting signal 204 is output from the load setting device 70 operated by the increasing operation device 68 or the decreasing operation device 69, and is input to the load change rate limiter 71. In the load change rate limiter 71, after the load setting signal 204 is increased or decreased by a value of a change rate selected in advance, the output signal 2
Output as 05. Then, the output signal 205 and the output signal 201 of the generator output detector 26 input to the plant control device 63 are subjected to subtraction processing in the subtractor 72, and the obtained deviation signal 206 is input to the proportional integration element 79. Then, a proportional integral calculation is performed. The value after the proportional integration process is input to the gasifier control unit 64 as a gasifier control command signal 207, and based on the gasifier control command signal 207, the input amounts of the coal and the oxidizer are controlled and calculated, Thereafter, it is output as a control command signal 208 of the coal amount adjusting device 2 and a control command signal 209 of the oxidizing agent amount adjusting device 3.

On the other hand, in the pressure control section 67, the increasing operation device 74 or the decreasing operation device
Pressure setting signal 21 from pressure setter 76 operated by 75
0 is output and input to the pressure change rate limiter 77. In the pressure change rate limiter 77, the pressure setting signal 210 is increased or decreased by a value of a preset change rate, and then output as an output signal 211. And this output signal 211,
The output signal 202 from the inlet pressure detector 27 of the fuel pressure control valve 6 input to the plant control device 63 is subjected to subtraction processing in a subtractor 78, and the deviation signal 212 obtained here is input to a proportional integration element 79. Then, a proportional integral calculation is performed. The value after the proportional integration process is input to the gas turbine control unit 65 as a gas turbine control command signal 213, and the fuel gas flow rate is controlled and calculated based on the gas turbine control command signal 213. It is output as a control command signal 215.

The signal 203 from the gas inlet pressure detector 28 of the fuel flow control valve 7 is input to the gas turbine controller 65. The control signal 214 is output to the fuel pressure regulating valve 6 based on the calculation result in the gas turbine control unit 65, and the control signal 214 causes the fuel pressure regulating valve 6 to always keep the gas inlet pressure of the fuel flow regulating valve 7 constant. It is controlled so that the fuel is cut off suddenly in the event of an abnormality or the like.

In this embodiment, a switch 80, a function generator 81, and a subtractor 82 as an increase / decrease setter are provided between a load control unit 66 and a pressure control unit 67.

The switch 80 receives the zero signal 216 or the output signal 212 from the subtractor 78 of the pressure controller 67. This switch 80
In this case, normally, the input of the zero signal 216 is selected, but when the control signal 213 from the pressure control unit 67 is in the non-selected state in the gas turbine control unit 65, that is, the gas turbine control is performed by another restriction control system. When the unit 65 is controlled and is in a state of being operated in the gas turbine following mode,
The input is switched from the zero signal 216 to the output signal 212 of the subtractor 78 of the pressure controller 67.

The output signal 217 from the switch 80 is input to the function generator 81 as a reference signal. In the function generator 81, when the output signal 212 from the subtractor 78 of the pressure control unit 67, which is a deviation signal, is input as the output signal 217, a reduction load according to the magnitude of the pressure deviation is set, and the reduction load signal 218 is output.

Then, the reduced load signal 21 output from the function generator 81
8 and the output signal 204 of the load setting unit 70 of the load control unit 66 are input to a subtractor 82, which performs a subtraction process. Then, the output signal 219 from the subtractor 82 is input to the load setting device 70.

The load setter 70 performs a run-back (pull-back) operation to increase or decrease the load set value based on the output signal 219, so that the load automatically changes to a value at which a desired fuel gas pressure is obtained.

According to such an embodiment, when the coal gasification power plant is operating in the gas turbine following mode, when the gas turbine control unit enters the limit control state, the gas turbine control unit 65 sets the non-selection state. The changed pressure deviation signal 212 is sent to the pressure controller 67 in the switch. Then, based on the magnitude of the pressure deviation of the signal 212, an optimal load is set for performing a run-back (pull-back) operation in the increasing or decreasing direction to the load set value. With this optimum load, the generated gas pressure is kept constant, and a desired fuel gas pressure can be obtained.

In addition, the restriction control of the gas turbine can cope with not only the restriction control according to the rise in the gas turbine inlet temperature but also all the restriction control in which the control command value from the pressure control unit is not selected.

〔The invention's effect〕

As described above, according to the coal gasification power plant according to the present invention, the load setting is increased or decreased according to the magnitude of the control deviation amount with respect to the control set value of the generated fuel gas pressure. In the gas turbine follow-up mode, even if the fuel gas consumption increases due to the increase in the fuel gas generated from the gasification furnace, the gas turbine inlet temperature limit control value is reached and the gas turbine limit control state is reached. The effect that the turbine can safely operate within the limit value, and that the optimum load operation and pressure operation can be performed is exhibited.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system showing an embodiment of a coal gasification power plant according to the present invention, FIG. 2 is a system diagram showing the entire system of the coal gasification power plant, and FIG. 3 shows a conventional example. It is a block diagram. 1 ... Coal gasifier (gasifier facility), 2 ... Coal amount controller (gasifier facility), 3 ... Oxidizer amount controller (gasifier facility), 7 ... Fuel flow control valve (Gas turbine equipment), 8: Combustor (gas turbine equipment), 10: Gas turbine (gas turbine equipment), 26: Generator output detector, 27: Pressure detector, 63: Plant control device , 64 ...
... Gasification furnace control section, 65 ... Gas turbine control section, 66 ...
Load control unit, 67 ... Pressure control unit, 70 ... Load setting unit, 76
…… Pressure setting device, 80 …… Switching device, 81 …… Function generator, 82
...... Subtractor (increase / decrease setter).

Claims (1)

(57) [Claims] 1. A gasifier facility for gasifying coal, a gas turbine facility using coal gas generated in the gasifier facility as a fuel, a steam turbine facility using heat from gas turbine exhaust gas, and each of the turbines In a coal gasification power generation plant having a generator provided in a facility and a plant control device for controlling the gasification furnace equipment and the gas turbine equipment, the plant control apparatus detects a gas pressure supplied from the gasification furnace. A pressure control unit that sets the gas pressure to a required value based on the value, a gas turbine control unit that controls the gas turbine equipment based on an output signal from the pressure control unit, and detects an output of the generator. A load control unit for setting the output to a required value, a gasification furnace control unit for controlling the gasification furnace equipment based on an output signal from the load control unit, A switch for taking out a deviation signal in the pressure control unit when the gas turbine equipment is deselected in a gas turbine pressure control under a turbine following mode; and a magnitude of the pressure deviation by inputting the deviation signal as a reference signal. Coal gas, comprising: a function generator that sets a reduced load according to the following equation; and a changer setter that increases or decreases a load set value of the load control unit based on an output signal of the function generator. Chemical power plant.