JPH02233807A - Coal gasification power generation plant control device - Google Patents

Abstract

PURPOSE:To obtain a locus equivalent to a load fluctuation time real load locus at the time of setting a constant pressure, by fluctuating a pressure setting signal by a set time delay in a delay element, later than fluctuation of a load setting signal at the time of load fluctuation. CONSTITUTION:A dead time element 44 serving as a delay time element is provided between a load control unit 34 and a pressure control unit 35. Hereat, a load setting signal from a load setting device 38 is inputted in this element 44, and the load setting signal as a reference signal is outputted toward a pressure setting device 41 after a prescribed dead time. Thereby, a timing when the real load starts its lifting at the time of load lifting, can become a timing when the gas turbine inlet pressure detected by a pressure detector 32 starts its rise, so that reducing operation for a fuel flow rate accompanying the lift of a pressure setting value, is not carried out on the gas turbine facility side. Therefore, a phenomenon in which the real load drops temporarily does not appear, and the locus of the real load becomes nearly same as the locus at the time of constant pressure operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) (Industrial Application Field) The present invention relates to a combined cycle power plant, and more particularly to a coal gasification power plant control device equipped with a coal gasification furnace.

(Prior art) Coal gasification combined cycle power generation converts coal into gas fuel and uses the combustion gas as a working fluid source to rotationally drive a gas turbine and compressor as well as a generator. It has been attracting attention in recent years due to its effective utilization and superiority in solving pollution problems.

The second coal gasification combined cycle power plant
As shown in the figure, a gas turbine plant 1 that rotates a turbine with combustion gas and a steam turbine plant 2 that rotates a turbine with steam generated using exhaust gas from the gas turbine plant 1 are coupled. The gas turbine plant 1 includes a gasifier equipment 3 that converts coal into gas fuel, and a gas turbine equipment 4 that burns the gas fuel from the gasifier equipment 3 to rotate a turbine. Be prepared.

The gasifier equipment 3 is equipped with a gasifier 5 that produces crude gas, and coal is fed into the gasifier 5 through a coal flow adjustment valve 6 and also through an oxidizer flow adjustment valve 7. Air is introduced as an oxidizing agent.

The crude gas produced in the gasifier 5 is sent to the gas purification device 9 via the gas cooler 8, where the fuel gas is
fWEJ, and the fuel gas is supplied to the combustor 12 via the fuel pressure regulating valve 10 and the fuel flow regulating valve 11. The combustor 12 is supplied with compressed air from a compressor 13 that pressurizes the atmosphere to produce compressed air, and in this combustor 12, combustion gas and compressed air react to produce combustion gas. do.

The generated combustion gas is sent to the gas turbine 14, and by rotating the gas turbine 14, the generator 15 is rotationally driven to generate electricity. Note that a part of the compressed air boosted by the compression unit 13 is extracted from the final stage of the compression unit 1113, and is further boosted in pressure by the electric motor-driven boost compressor 16, after which the oxidant is supplied to the oxidizer flow rate adjustment valve 7. Supplied as.

On the other hand, the steam turbine plant 2 includes an exhaust heat recovery boiler 18, and the combustion gas after rotating the gas turbine 14 is sent as exhaust gas to the exhaust heat recovery boiler 18, where the thermal energy of the exhaust gas is recovered. That is, the exhaust heat recovery boiler 18 is equipped with a super heater 19, a vaporizer 20, and an economizer 21 in order from the upstream side with respect to the flow of the exhaust gas, and steam is generated by these heat exchangers.

First, a part of the feed water heated by the economizer 21 is sent to the gas cooler drum 22, and the feed water is circulated from the gas cooler drum 22 to the gas cooler 8, and the steam generated during this period is transferred from the gas cooler drum 22 to the super heater 1.
Sent to 9th. Furthermore, (2) the remainder of the water supplied from the conomizer 21 is sent to the steam drum 23, the water is circulated from the steam drum 23 to the evaporator 20, and the steam generated during this period is sent to one superheater.

The steam thus sent to the super heater 19 becomes dry steam here, and from this one super heater the steam control valve 2
4 and is supplied to the steam turbine 25. The steam sent to the steam turbine 25 rotates the steam turbine 25,
Power generation R26 is driven to generate power. The steam expanded by rotating the steam turbine 25 is sent to the condenser 27, where it indirectly exchanges heat with cooling water and is brought to approximately room temperature.

The condensate that has reached room temperature is circulated to the economizer 21 via the feed water heater 28 and the deaerator 29, where it is vaporized again.

When operating the above-mentioned coal gasification waste bound cycle power generation plant, a gas turbine follow-up mode is selected in which the gasifier equipment 3 controls the load and the gas turbine equipment 4 controls the gas turbine inlet gas pressure (or the gas purifier outlet pressure). There is a gasifier follow-up mode in which the gas turbine equipment 4 performs load control and the gasifier equipment 3 controls the gas pressure at the gas turbine inlet, and the system can be operated in either of these modes depending on the purpose of operation. It is possible to do so.

Further, a variable voltage operation method aimed at improving partial load efficiency is known. In this method, the pressure setting of the gas turbine inlet gas pressure is set proportionally to the load setting, so the pressure control set value during partial load is kept low compared to that during constant pressure operation. The pressure inside the furnace can also be kept low, and as a result, the pressure boost compression type 1
It is possible to improve the rangeability by reducing the pressure boosting power of the oxidizing agent and coal input into the No. 6 gasifier 5, and by reducing the differential pressure between the flow rate regulating valves 6.7.

Figure 3 shows an example of a control circuit for controlling variable pressure operation in the gas turbine follow-up mode.
, a gasifier equipment 3 equipped with a coal flow control valve 6 and an oxidizer flow control valve 7, a combustor 12, a compressor 13, a gas turbine 14, a generator 15, a fuel pressure control valve 10, and a fuel flow control valve. A gas turbine installation 4 with 11 is shown.

A generated power detector 31 that detects the generated power of the generator 15 and a gas turbine inlet pressure detector 32 that detects the inlet pressure of the fuel pressure regulating valve 10 are connected to the gas turbine equipment 4. Detection signals from the gas turbine inlet pressure detector 31 and the gas turbine inlet pressure detector 32 are input to the plant control device 33.

The plant control device 33 includes a load control section 34 and a pressure control section 3.
5. Gasifier control unit 36 and gas turbine control unit 37
The load control unit 34 includes a generated power detector 31
The detection signal inputted from the load setting device 38 and the set value from the load setter 38 are inputted to the subtracter 39, and after the subtraction processing, the deviation signal is inputted to the proportional integral element 40 to perform proportional integral calculation. The value after the proportional integral processing is input to the gasifier control unit 36 as a gasifier control command signal, and after controlling and calculating the respective input amounts of coal and oxidizer based on the gasifier control command signal, the coal flow rate is A control command signal is output to each of the regulating valve 6 and the oxidant flow regulating valve 7.

In the pressure control unit 35, the pressure setting value outputted from the pressure setting device 41 using the output signal of the load setting device 38 as a reference signal and the detection signal from the gas turbine inlet pressure detector 32 are input to the subtracter 42. After the subtraction process, the deviation signal is input to the proportional-integral element 43 to perform proportional-integral calculation. The value after the proportional integral processing is input to the gas turbine control unit 37 as a gas turbine control command signal, and after the fuel gas flow rate is controlled and calculated based on the gas turbine control command signal, a control command signal is sent to the fuel flow rate adjustment valve 11. is output as

Incidentally, an example of setting the function of the pressure setting device 41 is shown in FIG. In this figure, the pressure setting value is obtained by giving the load setting value inputted as a reference signal to the horizontal axis.

With such a control system configuration, the gasifier equipment 3 has a load υ
Since the gas turbine equipment 4 performs pressure control at variable pressure settings, it is possible to obtain the required load and to set the gas system internal pressure to the value set for variable pressure operation.

(Problems to be Solved by the Invention) A major feature of the coal gasification bound cycle power plant is that the gasification furnace setting [5's control m + the length of the delay time constant] is can be mentioned. That is, the length of time it takes for the gas turbine control device 37 to detect the control deviation and operate the fuel flow adjustment valve 11 to reduce the control deviation to zero, and the length of time it takes for the gasifier control device 36 to detect the control deviation When comparing the length of time required to reduce the control deviation to zero by operating the coal flow suspension adjustment valve 6 and the oxidizer flow rate adjustment valve 7, the gasification furnace equipment 3 side is characterized by being longer.

Therefore, when variable pressure operation is performed in the gas turbine follow-up mode, the behavior of the actual load becomes a problem, especially in a transient state where the load is increased or decreased. This behavior will be explained using FIG. 5, taking as an example the case when the load increases.

In this figure, the horizontal axis shows time, the upper row on the vertical axis shows the load setting value or actual load at the load control section 34, and the lower row shows the pressure setting value at the pressure control section 35 or the actual pressure to be controlled. Each is shown below.

The load setting r1a starts increasing the load at the timing To, reaches the required load at the timing T2, and becomes a constant value. The pressure set value at that time receives the load set value as a reference signal and outputs the pressure set value, so the timing becomes the same value as the load set value and increases as indicated by the broken line X. Since the control command signal of the pressure control system 30 is input to and controlled by the gas turbine control unit 37, the actual pressure obtains almost the same trajectory as the pressure set value X.

On the other hand, as for the actual load, although the control command value increases in order to increase the input amount of coal and oxidizer as the load setting value a increases, after the input amount to the gasifier 5 changes. The gas turbine inlet pressure increases from As a result, the signal from the generated power detector 31 drops further than the actual load before the load rises, as shown by the solid line C, because the fuel flow adjustment valve 11 closes to prevent this. This shows the trajectory.

As is well known, a coal gasification combined cycle power plant generates a low amount of gas fuel power, so the gas turbine equipment 4 defines the minimum load that can be operated using this gas fuel, and If a situation occurs where the load drops, for example, by immediately switching to high-calorie liquid fuel such as kerosene,
The aim is to prevent an increase in carbon monoxide (Go) in the gas turbine exhaust gas that occurs when there is a misfire or a low flow rate of coal gasified fuel. As an example, if the load at the beginning of the load increase is the minimum load that allows load operation to be performed using coal gasified fuel, as the load increases, a temporary load decrease state occurs.
As a result, there is a risk that fuel switching will be performed on the gas turbine equipment 4 side.

The present invention has been made in consideration of the above-mentioned circumstances, and is a coal gasification power generation plant that can obtain a trajectory equivalent to the actual load trajectory during load fluctuations when constant pressure is set even during variable pressure operation in gas turbine follow-up mode. The purpose is to provide a control device.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides gas controlled by a pressure control system that detects the gas pressure supplied from a coal gasifier and makes the pressure a constant pressure at a required variable pressure stage. It has a turbine facility and a gasifier facility that is controlled by a load control system that detects the power generation system output and makes the output the required output, and the load control system controls the load setting from the pressure control system. In the coal gasification power generation control system which inputs the signal as a reference signal and outputs a pressure setting signal in accordance with this load setting signal, inputs the load setting signal from the pressure υJtil system to the load control system through a delay element, When the load fluctuates, the pressure setting signal is varied with a delay set in the delay element compared to the variation of the load setting signal.

(Function) When the load changes, the pressure setting signal changes with a delay of the set time in the delay time element compared to the change in the load setting signal.
When the load increases, the timing at which the actual load starts to increase can be set to the timing at which the gas turbine inlet pressure starts to increase, and the gas turbine equipment side does not reduce the fuel flow rate as the pressure setting value increases. The phenomenon in which the actual load temporarily drops no longer appears, and the trajectory of the actual load becomes almost the same as the trajectory during constant pressure operation.

(Embodiment) An embodiment of the coal gasification power plant application system according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1, the same parts as in FIG. 3 are given the same reference numerals, and redundant explanation will be omitted. A dead time element 44 as a delay time element is provided between the load control section 34 and the pressure control section 35, and a load setting signal from the load setting device 38 of the load control section 34 is input to the dead time element 44. , outputs a load setting signal as a reference signal to the pressure setting device 41 of the pressure control controller 35 at the elapse of a predetermined dead time. wasted time element 44
The set time is assumed to be the dead time T1 until the start of the load increase in the trajectory b of the actual load increase when the pressure setting is set to the constant pressure setting Z in FIG.

In this embodiment, the load setting signal from the load setting device 38 passes through the dead time element 44 and is input to the pressure setting device 41 with a delay of the dead time T1, so that the pressure setting value is indicated by the solid line y.
As shown in , the ascent starts after the dead time T1 passage.

Therefore, between To and T, the gas turbine equipment 4 side is under pressure. Since the fuel flow m is no longer reduced as the fixed value increases, the phenomenon of temporary drop in the actual load no longer occurs, and the actual load is maintained at a constant pressure [2] as shown by the broken line b. It fluctuates along a trajectory similar to that of .

As a result, it becomes possible to deal with problems that have conventionally been dealt with by lowering the load change rate without lowering the load change rate.

Although the above embodiment has been described only when the load increases, the same effect can be obtained when the load decreases.

〔Effect of the invention〕

In the present invention, the load setting signal from the pressure control system is input to the load υ1 control system through the delay element, and when the load changes, the pressure setting signal is varied by delaying the variation of the load setting signal by the set time at the delay element. Even when variable pressure operation is performed in the gas turbine follow-up mode, it is possible to obtain a trajectory equivalent to the actual load trajectory during load fluctuations when the constant pressure is set.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a coal gasification power plant control device according to the present invention, Fig. 2 is an overall system diagram showing a general coal gasification combined cycle power plant, and Fig. 3 is a block diagram showing an embodiment of a coal gasification power plant control device according to the present invention. A block diagram showing a coal gasification power generation plant control device, Fig. 4 is a characteristic diagram showing the PA relationship between the pressure setting value of the pressure setting device and the load setting value in Fig. 3, and Fig. 5
The figure is a dimensional characteristic diagram showing fluctuations in pressure and load. 3...Gasifier installation, 4...Gas turbine equipment, 5
...Gasifier, 6.. Coal flow adjustment valve, 7.. Oxidizer flow adjustment valve, 10.. Fuel pressure adjustment valve, 11..
・Fuel flow rate adjustment valve, 12... Combustor, 13... Compressor, 14... Gas turbine, 15... Generator, 31
... Power generation output detector, 32... Gas turbine inlet pressure detector, 33... Plant control device, 34... Load control section, 35... Pressure control section, 36... Gas Chemical furnace control section, 37... Gas turbine control section, 38...
Load setting device, 39. ...Sieve reducer, 40...Proportional integral element, 41...Pressure setting device, 42...Subtractor, 43.
...proportional integral element, 44...dead time element. Applicant's agent Hisako Hatano T4L
- Figure 4 Figure 1 TQ TI T2 Figure 5

Claims (1)

[Claims] The gas turbine equipment is controlled by a pressure control system that detects the gas pressure supplied from the coal gasifier and converts that pressure into the required transformation setting pressure, and the gas turbine equipment that detects the power generation system output and The gasifier equipment is controlled by a load control system that functions to make the output the required output, and the load control system inputs a load setting signal from the pressure control system as a reference signal, and according to this load setting signal, In the coal gasification power plant control device that outputs the pressure setting signal, the load setting signal from the pressure control system is input to the load control system through the delay element, and when the load changes, the setting is performed by the delay element rather than the fluctuation of the load setting signal. A coal gasification power plant control device characterized by varying a pressure setting signal with a delay of time.