JPH084555A - Coal gasification power plant - Google Patents

Abstract

PURPOSE:To provide a coal gasification power plant which is constituted to feed a desired pressure and a desired flow rate of air to a gasifying furnace even when disconnection of a load occurs. CONSTITUTION:In a coal gasification power plant having a gas turbine control device 15 to control a fuel flow rate regulating valve 5 and the compressor inlet variable stationary blade drive device 7 of a gas turbine, the gas turbine control device 15 is provided with means 29 and 30 to hold an opening at a value available before the starting of disconnection of a load until the opening of a compression inlet variable stationary blade is lowered to a value, at which a gasifying furnace input amount is determined, when disconnection of a load occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal gasification power generation plant, and more particularly, to gasification when a negative cutoff occurs by improving a control technique of a compressor inlet guide variable stator vane of a gas turbine, which is one of the constituent elements. The present invention relates to a coal gasification power generation plant that secures a supply flow rate and pressure of an oxidant (air) to a furnace.

[0002]

2. Description of the Related Art A coal gasification power plant is one that gasifies coal, burns the gas in a gas turbine combustor, and drives a gas turbine and a generator, and is advantageous in effective use of energy and prevention of pollution. Attention is paid to such points.

FIG. 4 is a schematic system diagram of such a coal gasification power generation plant. The gasification furnace 1 produces a crude gas under high temperature and high pressure, and the coal gas flows into the gasification furnace 1 via the coal amount adjusting device 2 and the air via the oxidant amount adjusting device 3. Oxidizing agent such as.

The crude gas produced in the gasification furnace 1 is sent to a gas refining apparatus 4, where it is desulfurized and dedusted, and then becomes a purified gas combustible in a gas turbine. The purified gas flows into the combustor 8 via the fuel flow rate control valve 5 and is burned by the air whose pressure is increased by the compressor 6.
The combustion gas is guided to the gas turbine 9 to drive the turbine, and in the combined cycle power generation facility, the exhaust gas of the gas turbine 9 is guided to an exhaust heat recovery boiler (HRSG) (not shown) to exchange heat with water or steam, Not to drive a steam turbine.

A part of the air boosted by the compressor 6 is extracted from the final stage of the compressor 6, and the motor 1
After being boosted by the air booster 11 driven by 2,
It is supplied to the gasification furnace 1 via the oxidant flow rate adjusting device 3.

On the other hand, in the gas turbine control device 15, the control command signal 10 is sent to the fuel flow rate control valve 5 of the gas turbine and the compressor inlet guide variable stator vane (IGV) drive device 7.
1, 102 are output. As the control elements of the compressor inlet guide variable stator vane drive device 7, the detection signals 103 and 104 from the gas turbine compressor discharge pressure detection device 13, the gas turbine exhaust gas temperature detector 14 and the like are input. There is.

FIG. 5 illustrates the circuit configuration of the gas turbine control device 15. That is, the gas turbine control device 15
Is a fuel flow rate control valve 5 and a compressor inlet variable stator vane drive device 7.
It is designed to control and.

A load / speed control system 21 and an exhaust gas temperature limiting control system 22 are provided for controlling the fuel control valve 5, and an output signal 105 from these load / speed control system 21 is provided.
And an output signal 106 from the exhaust gas temperature limit control system 22 are input to the low value priority circuit 23 as an opening degree command according to an operating state such as a load request state. Low value priority circuit 2
In 3, the lower one of the two input signal values is selected as the control command signal and is output as the opening signal 101 of the fuel flow rate control valve 5.

A compressor inlet variable stator vane control system 24 is provided for controlling the compressor inlet variable stator vane driving device 7. In the compressor inlet variable vane control system 24, the compressor discharge pressure signal 10 from the compressor discharge pressure detector 13 is output.
3 is input to the function generator 25 as a reference signal. In this function generator 25, the control set value of the exhaust gas temperature obtained when the gas turbine inlet temperature is constant is given as a function from the respective relationships of the inlet temperature and inlet pressure of the gas turbine 9 and the exhaust gas temperature and exhaust gas pressure. To be The output signal 107 from the function generator 25 and the exhaust gas temperature detector 1
The exhaust gas temperature signal 104 from 4 is subjected to subtraction processing by the subtractor 26, and the deviation value signal 1 output from the subtractor 26
08 is input to the PI controller 27, and after PI control calculation,
It is output to the compressor inlet variable stator vane drive device 7 as a compressor inlet variable stator vane opening command signal 102.

With such a control circuit configuration, on the gas turbine 9 side, the opening of the fuel flow rate control valve 5 is controlled so that the temperature is within the gas turbine exhaust gas temperature limit, and the combined power generation is performed. The compressor inlet variable stator vane opening is controlled so that the exhaust gas temperature becomes the highest within the gas turbine inlet temperature limit range so that the combined efficiency is improved even when the system is partially loaded. The flow rate is controlled.

[0011]

The behavior especially when load shedding occurs will be examined. FIG. 6 exemplifies the behavior of the process amount of each part when a load shedding occurs in the coal gasification power plant.

After the load is cut off, the fuel flow rate control valve 5 of the gas turbine 9 restricts the gas fuel flow rate c to a flow rate at which the no-load rated speed (FSNL) can be secured in order to suppress the increase in the gas turbine shaft speed. ing. In the gas turbine 9, the exhaust gas temperature decreases as the supplied fuel decreases, so the opening d of the compressor inlet variable stator vane is narrowed down to the opening corresponding to the no-load rated speed by the exhaust gas temperature control.

The compressor discharge pressure e decreases to a pressure equivalent to the no-load rated speed because the compressor suction flow rate decreases due to the decrease of the gas fuel flow rate c and the throttle operation of the opening d of the compressor inlet variable stator vane. To do.

Since the air booster pressure ratio f is increased from the discharge pressure of the gas turbine compressor to the gasifier required pressure,
The air booster pressure ratio f rises as the gas turbine compressor discharge pressure e drops.

On the other hand, as for the process amount on the gasifier side, the coal amount adjusting device 2 is used, though the gasifier input demand a controlling the input amount of the gasifier is started by the occurrence of load interruption.
Because the maximum rate of change is small (because coal is supplied by a rotary feeder, etc.) and the rate of temperature change of the gasifier is limited, the runback rate is about 10% / min at the maximum. Load (generally about 50%)
It takes about 5 minutes to descend. As the demand for the gasifier goes down, the amount of air introduced into the gasifier also decreases.

Here, focusing on the pressure ratio f of the air booster 11 and the supply air flow rate (equal to the gasification furnace input air amount b), FIG. 7 shows the pressure ratio-flow rate characteristics of the air booster 11.

When the flow rate of the supplied air is enormous, the air booster 1
An axial-flow type compressor is often used for 1. The operation characteristic of the compressor when the compressor is operated by the electric motor at a constant rotation speed is a curve that descends to the right as shown by the line b in FIG. 7. Rated operating condition (gasifier input demand (GID)
Is 100%), the operating point at the lowest load of the gasification furnace (corresponding to GID = 50%) is the point j on the high pressure ratio and low supply air flow rate side. This is because the required pressure of the gasification furnace 1 is constant, whereas the pressure ratio rises because the compressor discharge pressure during partial load of the gas turbine is low, but the gasification furnace required air flow rate is low. is there.

The operating point j does not exist on the compressor operating characteristic line g because the air booster 11 has a bypass line (not shown). By circulating the air through this bypass line, the compressor operates. It is possible to generate a required pressure ratio and supply a desired low air amount to the supply side. That is, the desired air flow rate can be supplied by increasing the pressure in a region where both the pressure ratio and the flow rate of the compressor operating characteristic line g are small. In FIG. 7, an operating line from the operating point j to the operating point h is an operating line from the minimum load to the rated load when the gasification furnace 1 and the gas turbine 9 perform the linked operation.

However, the operating point of the air booster 11 becomes k from immediately after the load is cut off until the gasifier 1 runs back with a sufficient partial load. That is, the required air flow rate is 100% for the gasifier input demand (GID),
The pressure ratio will require a higher value. Although the operating point may momentarily deviate from the characteristic line g to a region where both the pressure ratio and the supply air flow rate are high, the only characteristic of the compressor is the ability on the characteristic line g, so that the high flow rate in minutes is high. Is required, the discharge pressure of the air booster 11 cannot be maintained. As a result, the required air amount of the gasification furnace 1 cannot be covered, and a cross-limit operation of air and coal occurs on the gasification furnace side.

On the contrary, when the air booster 11 having a compressor characteristic of m is selected to allow the operating point k, the circulating flow rate of the bypass line of the air booster 11 is always maintained even during the rated operation. This will result in a very inefficient device selection.

It is also conceivable to start the compressor for starting the gasification furnace after the load is cut off.
It takes about a minute to start the compressor capable of supplying a flow rate of several tens of T / H, so it is difficult to cover the required air amount.

The present invention has been made in view of such circumstances, and provides a coal gasification power generation plant capable of supplying air of a desired pressure and flow rate to a gasification furnace even when a load cutoff occurs. The purpose is to do.

[0023]

In order to achieve the above-mentioned object, the invention according to claim 1 is a gasification furnace for gasifying coal, and a gas purification apparatus for purifying gas generated in this gasification furnace. A coal gasification power plant including a compressor and a combustor for burning purified gas, and a gas turbine and a generator driven by the combustion gas, wherein a fuel flow control valve for the gas turbine and In a gas turbine controller that controls the opening of the compressor inlet variable vane, the gas turbine controller determines the opening of the compressor inlet variable vane by the gasifier input amount when a load cutoff occurs. It is characterized by having a means for holding the opening degree before the start of the load shedding until the value falls to the predetermined value.

According to a second aspect of the present invention, in the coal gasification power plant according to the first aspect, the means for holding the opening of the variable compressor vane is used to vary the compressor inlet using the gasifier state quantity as a reference signal. The function generator outputs a stationary blade opening setting function.

According to a third aspect of the present invention, in the coal gasification power generation plant according to the second aspect, the gasifier state quantity serving as the reference signal of the function generator is used as the gasifier input demand.

According to a fourth aspect of the present invention, in the coal gasification power generation plant according to the second aspect, the gasifier state quantity serving as the reference signal of the function generator is the amount of generated gas generated from the gasifier. Is.

According to the invention of claim 5, a gasification furnace for gasifying coal, a gas purification device for purifying the gas generated in the gasification furnace, a compressor and a combustor for burning the purified gas. And a coal gasification power plant including a gas turbine and a generator driven by combustion gas, wherein the compressor inlet variable stator vane opening is controlled so that the gas turbine exhaust gas temperature becomes a preset temperature. In one having a compressor inlet variable vane control system, the compressor inlet variable vane control system comprises a function generator having a gasifier state quantity as a reference signal, and an opening command given from an exhaust gas temperature limiting control system. And a low value priority circuit that selects a high value of the opening command given from the function generator to control the compressor inlet variable stator vane opening.

According to a sixth aspect of the present invention, in the coal gasification power plant according to the fifth aspect, the gasifier state quantity serving as the reference signal of the function generator is used as the gasifier input demand.

According to a seventh aspect of the present invention, in the coal gasification power generation plant according to the fifth aspect, the gasifier state quantity serving as the reference signal of the function generator is the amount of generated gas generated from the gasifier. Is.

According to the invention of claim 8, instead of the low value priority circuit of the coal gasification power plant according to claim 5, the control system is switched to the function generator side by a load cut-off generation signal to change the compressor inlet variable stationary blades. A feature is that a signal switching circuit for controlling the opening is provided.

According to a ninth aspect of the present invention, in the coal gasification power generation plant according to the eighth aspect, a control signal, which is attached to a signal switching circuit and is switched by a load cutoff generation signal, has a predetermined gasification furnace input amount. It has a condition holder that switches to the exhaust gas temperature control system depending on the condition that it has reached the specified value.

According to a tenth aspect of the present invention, instead of the low value priority circuit of the coal gasification power generation plant according to the fifth aspect, a bias setting circuit for opening the compressor inlet variable stator vane by the state quantity on the gasification furnace side is provided. It is characterized in that a functional adder is provided.

[0033]

According to the present invention, the gas turbine exhaust gas temperature control system functions as in the conventional case during the normal operation in which the loads of the gasification furnace and the gas turbine are matched.

On the other hand, in a state where the gasifier load is high and the gas turbine load is low, that is, after the load is cut off, the compressor inlet variable static pressure given along the gasifier state quantity such as the gasifier demand is given. The blade opening acts so as to maintain the opening direction.

Originally, in order to improve the power generation efficiency under partial load, the compressor inlet variable stator vane in combined power generation reduces the compressor flow rate by closing the compressor inlet variable stator vane to reduce the exhaust gas temperature. In the present invention,
The variable inlet vane of the compressor is held at the maximum opening at the partial load or the no-load rated speed to match the gasification furnace.

Therefore, according to the coal gasification power generation plant of the present invention, even if the gasifier load and the gas turbine load are unmatched as in the case of load shedding, the desired air pressure on the gasifier side and It becomes possible to supply a flow rate.

[0037]

EXAMPLE An example of a coal gasification power plant according to the present invention will be described below with reference to FIG.

Since the plant equipment configuration other than the gas turbine control device is the same as the conventional one, refer to FIG. 4 as it is. Further, in FIG. 1, the same components as those of the related art are designated by the same reference numerals as those of FIG. 5, and the duplicate description thereof will be omitted.

In the present embodiment, as shown in FIG. 1, as the gas turbine control device 15, the output signals 105 and 106 of the load speed control system 21 and the exhaust gas temperature limit control system 22 are input to the fuel flow rate control valve 5. It has a low value priority circuit 23 that outputs an opening degree signal 101, and a compressor inlet variable stator vane control system 24.

When the load cutoff occurs in the compressor inlet variable vane control system 24, the opening degree of the compressor inlet variable vane is decreased until the gasifier input amount drops to a predetermined value. A function generator 29 and a low value priority circuit 30 are provided as a means for holding the function. The function generator 29 uses the gasifier state quantity, for example, the gasifier input demand signal 109 output from the gasifier input detection unit 28, as the reference signal. The gasifier input demand signal 109 generally indicates the gasifier heat input (or gasifier load) as a percentage, and based on this signal, the input amount of coal and air to the gasifier is It is given uniquely.

The function generator 29 outputs a compressor inlet variable stator vane opening signal 110 according to the gasifier input demand, and this signal 110 is used to open the compressor inlet variable stator vane from the PI controller 27. Of the compressor inlet variable stator vane opening direction, which is input to the low value priority circuit 30 together with the degree signal 102,
That is, it is a circuit that preferentially selects a signal in the direction of increasing the inflow rate of the compressor 6.

Next, the operation of this embodiment will be described.

During normal operation in which the loads of the gasification furnace and the gas turbine are matched, the gas turbine exhaust gas temperature control system functions as in the conventional case.

On the other hand, when the gasifier load is high and the gas turbine load is low, that is, after the load is cut off, the compressor inlet variable stator vane opening given along the gasifier demand is in the opening direction. Acts to hold.

The movement of each process amount after the occurrence of load shedding will be described with reference to FIG. 6 as follows. That is, according to the present embodiment, the locus of the compressor inlet variable vane opening becomes d'in FIG. 6, and as a result, the locus of the compressor discharge pressure e'and the air booster pressure ratio f'is obtained. (The final process amount of the original no-load rated speed (FSNL) is obtained with the gasifier runback).

Originally, in order to improve the power generation efficiency at the time of partial load, the compressor inlet variable stator vane in combined power generation reduces the compressor flow rate by closing the compressor inlet variable stator vane to reduce the exhaust gas temperature. In the present embodiment, the compressor inlet variable stator vane is held at the maximum opening at the time of partial load or no-load rated speed to match the gasifier.

As described above, according to the coal gasification power generation plant of this embodiment, even if the load of the gasifier and the load of the gas turbine are unmatched as when the load is cut off, a desired gasifier side is desired. It is possible to supply air pressure and flow rate.

Next, two other embodiments of the present invention will be described with reference to FIGS. 2 and 3, respectively.

The other embodiment shown in FIG. 2 differs from the one embodiment shown in FIG. 1 in that the low value priority circuit 30 is replaced by a PI.
A switch 31 is provided on the output side of the controller 27, and when the load is cut off, the compressor inlet variable stator vane control system 24 outputs the output signal 110 from the function generator 29 using the gasifier input demand signal 109 as a reference signal. There is a point to switch.

The condition holder 32 performs a flip-flop operation. The condition holder 32 operates on the "setting" (S) side depending on the load cutoff generation condition, and the switch 31 operates the gasifier input demand side ( Input a) is selected. As a result, the compressor inlet variable stator vane drive device 7 outputs an operation signal along with the output from the function generator 29.

When the compressor inlet variable stator vane opening equivalent to the no-load rated speed (FSNL) is reached, the condition holder 32 is released.
In the switch 31 operating on the "reset" (R) side, the input on the PI controller 27 side (b side) is selected. As a result, the control shifts to normal control.

Further, in another embodiment shown in FIG. 3, an adder 23 is provided on the output side of the PI controller 27 in place of the low value priority circuit 30 shown in FIG. 1, and the setting of the function generator 29 is biased. The value is given as a setting and the unbalanced amount between the gasification furnace 1 and the gas turbine 9 is corrected.

The function generator 29 in the embodiment of FIG.
The reference signal input to is not limited to the gasifier input demand signal, and may be any signal as long as it is a signal that can obtain the state quantity as the gasifier input amount, for example, the generated gas generated from the gasifier. It may be a flow rate.

Also according to the other embodiments described above, after the load is cut off, the compressor inlet variable stator vane opening given along the gasifier state quantity acts so as to maintain the opening direction, and gasification is performed. Matching with the furnace can be achieved.

[0055]

As described above in detail, according to the coal gasification power plant according to the present embodiment, even if the gasifier load and the gas turbine load are unmatched, such as when the load is cut off, the gas It is possible to supply a desired air pressure and flow rate to the gasification furnace side.

[Brief description of drawings]

FIG. 1 is a block diagram of a gas turbine control device, showing an embodiment of a coal gasification power generation plant according to the present invention.

FIG. 2 is a block diagram of a main part showing another embodiment of the present invention.

FIG. 3 is a block diagram of a main part showing another embodiment of the present invention different from the above.

FIG. 4 is a system diagram showing the overall configuration of a coal gasification power generation plant.

FIG. 5 is a block diagram showing a gas turbine control device of a conventional coal gasification power generation plant.

FIG. 6 is a time chart showing changes in the main process amounts of the gasification furnace and the gas turbine when load shedding occurs.

FIG. 7 is a graph showing pressure ratio and flow rate characteristics of the air booster.

[Explanation of symbols]

 1 Gasification furnace 2 Coal amount adjusting device 3 Oxidant amount adjusting device 4 Gas refining device 5 Fuel flow rate control valve 6 Compressor 7 Compressor inlet guide variable stator vane (IGV) drive device 8 Combustor 9 Gas turbine 11 Air booster 12 Electric motor 13 Gas turbine compressor discharge pressure detector 14 Exhaust gas temperature detector 15 Gas turbine controller 21 Load and speed control system 22 Exhaust gas temperature limit control system 23 Low value priority circuit 24 Compressor inlet variable stator vane control system 25 Function generation Device 26 Subtractor 27 PI controller 30 Low value priority circuit 29 Function generator 28 Gasification furnace input detection unit 101, 102 Control command signal 103, 104 Detection signal 105, 106, 107 Output signal 108 Deviation value signal 109 Gasification furnace Input demand signal 110 Output signal

Claims (10)

[Claims] 1. A gasification furnace for gasifying coal, a gas purification device for purifying the gas generated in the gasification furnace, a compressor and a combustor for burning the purified gas, and a drive by the combustion gas. A coal gasification power plant including a gas turbine and a power generator, wherein the gas turbine control device controls the opening of a fuel flow rate control valve of the gas turbine and a compressor inlet variable stator vane, The gas turbine control device has means for holding the opening degree of the compressor inlet variable vane at the time of load cutoff until the gasification furnace input amount drops to a predetermined value before the load cutoff is started. A coal gasification power generation plant characterized by the above. 2. The function generator for holding the opening degree of the variable compressor vane is a function generator which outputs a compressor inlet variable vane opening setting function using the gasifier state quantity as a reference signal. Coal gasification power plant. 3. The coal gasification power plant according to claim 2, wherein the gasifier state quantity serving as a reference signal for the function generator is a gasifier input demand. 4. The coal gasification power plant according to claim 2, wherein the gasification furnace state quantity serving as a reference signal of the function generator is an amount of generated gas generated from the gasification furnace. 5. A gasification furnace for gasifying coal, a gas purification device for purifying the gas generated in the gasification furnace, a compressor and a combustor for burning the purified gas, and a drive by the combustion gas. A coal gasification power generation plant including a gas turbine and a generator, the compressor inlet variable stator vane for controlling the compressor inlet variable stator vane opening so as to set a gas turbine exhaust gas temperature to a preset temperature. In the one having a control system, the compressor inlet variable blade control system is provided with a function generator having a gasifier state quantity as a reference signal, an opening command given from an exhaust gas temperature limit control system, and the function generator. And a low value priority circuit for controlling a compressor inlet variable stator vane opening degree by selecting a high value of an opening degree command that is applied to the coal gasification power plant. 6. The coal gasification power plant according to claim 5, wherein the gasifier state quantity serving as a reference signal of the function generator is a gasifier input demand. 7. The coal gasification power plant according to claim 5, wherein the gasification furnace state quantity serving as a reference signal of the function generator is an amount of produced gas generated from the gasification furnace. 8. A signal for controlling the compressor inlet variable stator vane opening by switching the control system to the function generator side by a load cutoff generation signal instead of the low value priority circuit of the coal gasification power generation plant according to claim 5. A coal gasification power plant characterized by having a switching circuit. 9. A condition holder attached to the signal switching circuit, for switching the control signal switched by the load cutoff generation signal to the exhaust gas temperature control system on the condition that the gasifier input amount reaches a predetermined value. The coal gasification power generation plant according to claim 8. 10. The coal gasification power plant according to claim 5 is replaced with a low value priority circuit, and an adder is provided which functions as a bias setting circuit for opening the compressor inlet variable vane according to the state quantity on the gasification furnace side. A coal gasification power plant characterized by