JPS6340923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal gasification power generation method for generating power using coal gasification gas as fuel, and a coal gasification power generation plant used in the power generation method. In particular, the present invention relates to a coal gasification power generation method for generating power by driving a gas turbine with fuel gas supplied from a coal gasifier, and a power generation plant thereof.

In this type of technology, many technical problems remain to be solved because the coal gasification gas used as fuel has a low calorific value and poor combustion stability. In particular, during dumping when the flame has attenuated, there is a high possibility that the combustion gas will become unstable and a state where it appears to be blown out, that is, so-called blow-out, will occur, and solving this problem is an important technical issue.

That is, unlike coal gasification gas, the fuel gas mainly used in conventional gas turbines has a high calorific value and a wide stable combustion range. Therefore, even if the need for damping arises during normal operation and the damping is to be performed to the maximum no-load state during rated load operation, damping can be achieved simply by reducing the fuel flow rate, and even in that state, the gas It is said that it burns stably and has a reliable flame-holding effect.

However, in gas turbines using coal gasification power generation technology, the coal gasification gas fuel used as fuel contains few combustible components and is considerably diluted with nitrogen, so the calorific value is approximately 8 The range of fuel-air ratios in which stable combustion can be achieved is also narrow. For this reason, when dumping, simply restricting and reducing the fuel flow rate in the same way as in the past will result in an unstable combustion state midway through, making it impossible to maintain combustion.
It is thought that so-called blow-out will occur.

However, despite the above-mentioned circumstances, no proposal has yet been made to solve the dumping problem in coal gasification power generation technology. Only a few techniques have been developed to stabilize the initial flame by using auxiliary fuel during ignition and start-up. Therefore, the present inventors focused on this problem during dumping, and based on the above-mentioned background, in coal gasification power generation technology, we have developed a technology to solve the above-mentioned problem by providing a new fuel control system different from the conventional one. We believe that this is an urgent need and have developed the present invention.

Furthermore, in fuel control during dumping of such a gas turbine, it is desirable that responsiveness be excellent. This is because if the responsiveness is poor, it may not be possible to respond quickly at the time of dumping, resulting in inconveniences such as a blowout occurring. This problem can be said to be particularly important in power generation using coal gasified gas, which has problems with combustion stability as described above.

In view of the above-mentioned circumstances, an object of the present invention is to provide an advantageous coal-fired fuel that can be easily controlled during dumping of a gas turbine, does not blow out, and can be controlled with excellent responsiveness. An object of the present invention is to provide a gasification power generation method and a coal gasification power generation plant.

To achieve this objective, the present invention stores auxiliary liquid fuel in advance and supplies this auxiliary liquid fuel to the combustor of the gas turbine at the time of load shedding, thereby stabilizing the flame in the combustor at the time of load shedding. The structure is to be adjusted.

With this configuration, when the gas turbine dumps, the coal gasification gas supply line is cut off by the accompanying load cut signal, etc., and the line is quickly switched to supply the above-mentioned auxiliary liquid fuel, thereby stabilizing the system. Can hold a strong flame. Moreover, since the auxiliary liquid fuel can be stored in a way that allows quick response, it can be configured to respond instantly to load shedding without using a drive source with poor response such as a pump, resulting in a highly responsive system. can get things. Further, even if a drive source such as a pump is used, a storage fuel supply line that can quickly respond can be provided separately from the drive source, so that the delay time until the pump starts up can be satisfied.

Further, the above configuration can be effectively applied to conventionally developed coal gasification power generation technology. In other words, in the coal gasification power generation technology that has been developed so far, liquid fuel with good combustion performance is used for auxiliary combustion during ignition and start-up of the gas turbine combustor. Therefore, if an improvement is made so that this liquid fuel supply line can also be used during load interruption and auxiliary liquid fuel stored in a fuel tank or the like can be supplied from this line, the present invention can be implemented with great ease. It can also be applied to the previous version.

In implementing the present invention, a structure may be adopted in which liquid fuel for load shedding is stored in advance in an accumulator. When a load shedding signal is received, the pressure of the gasifier can be used as a driving source for the liquid fuel. Alternatively, other pressure sources may be used, and these pressure sources and the opening and closing of valves provided in the lines can supply auxiliary liquid fuel to the combustor with faster response than a pump. I can do it.

By installing both a line that supplies auxiliary liquid fuel from the fuel tank using a pump and a line that supplies auxiliary liquid fuel from the accumulator using a pressure source, auxiliary liquid fuel can be immediately supplied from the accumulator. However, after the pump starts up, the fuel can be supplied from the fuel tank, which solves the problem of the delay time until the pump starts up, and also makes it possible to save power.

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a schematic diagram of the configuration of a coal gasification power plant in this example.

This power generation plant combusts fuel gas supplied from a coal gasifier 2 in a combustor 1, drives a gas turbine 4 with this combustion gas, and uses the power to generate electricity in a generator 21.

In the present invention, auxiliary liquid fuel is stored in advance, and in this example, both the accumulator 5 and the fuel tank 22 store this. At the time of load shedding, the auxiliary liquid fuel is supplied from the accumulator 5 to the combustor 1 of the gas turbine 4 to stabilize the flame in the combustor 1 at the time of load shedding. Next, when the drive means such as the pump starts up, the tank 2 is replaced with the accumulator 5.
Auxiliary fuel supply starts from 2. In this example, the auxiliary liquid fuel is supplied from the accumulator 5 by the pressure of the main fuel gas from the coal gasifier 2 passing through the line 19.

More specifically, this embodiment has the following configuration.

During normal operation, gasified fuel is supplied from the coal gasifier 2 to the combustor 1 through the fuel supply line 8 . This fuel flow rate is controlled by a flow rate control valve (CV-1) 7 on the line 8.
An air compressor 3 is provided, and air is supplied to the compressor 3.
The air is supplied to the combustor 1 through an air line 18 and used for combustion of fuel gas in the combustor 1 and for diluting and cooling the liner. The combustion gas 20 after combustion in the combustor 1 rotates the turbine 4, and is then discharged outside the plant.

In this example, light oil is stored in the fuel tank 22 as liquid fuel for igniting and starting up the combustor. Therefore, in this embodiment, this light oil is also used as a fuel for load shedding. tank 22
is also connected to the storage accumulator 5. Therefore, a system is connected from the light oil tank 22 through the pump 6, through the line 13 to the accumulator 5, and through the line 15 to the flow control valve (CV-2).
There are two systems, one leading to the combustor 1 via 16. The system passing through the line 15 also supplies light oil fuel at the time of ignition and start-up, and in this example, this system serves as both a line for both the time of ignition and start-up and the time of load shedding.

Line 1 is connected from the accumulator 5 to the combustor 1.
1, a stop valve (V-2) 9, and a throttle 10, leading to the combustor 1. A method is adopted in which stop switching is performed from the gasifier.

On the other hand, in order to supply fuel from the line 15 directly leading from the light oil tank 22 to the combustor 1, the pressure in the line 15 can be made higher than the pressure in the combustor 1. During load shedding,
As a result of the reduced load, the pressure in the combustor 1 has decreased and therefore the fuel supply to the combustor 1 through this line is easier. If you just want to supply light oil to the combustor 1, use the line 1 via the accumulator 5.
It is possible to continue using only the supply systems 3 and 11, but if this line 15 is used, the power of the pump 6 will be smaller than if lines 13 and 11 are used, as will be explained in detail later, and power can be saved. .

However, since this line 15 supplies auxiliary liquid fuel through the pump 6, there remains a problem in responsiveness. If the purpose is simply to supply auxiliary liquid fuel to the combustor 1, it may be thought that a system such as the accumulator 5 of this example may not be adopted and only a system using this line 15 may be sufficient. As mentioned above, line 15 has a problem with responsiveness, so lines 13 and 11 are also used. The response of the line 15 using the pump 6 will be briefly described below.

Please refer to FIG. Now, via line 15,
Let X be the time point at which the pump 6 wants to send auxiliary fuel to the combustor 1. This time point corresponds to the time of ignition/start-up and the time of load shedding. The pump 6 starts operating from time point X, but the pump pressure becomes sufficient at time point Y after a certain delay time. Therefore, at this point Y, the flow control valve 16 in the line 15 is opened to send auxiliary fuel to the combustor 1. This is because unless the pump pressure reaches a certain level, supply cannot be achieved even if the valve 16 is opened. Therefore, this line 1
If No. 5 is used, it will take time for the pump to start up, resulting in poor responsiveness. Therefore, it is not preferable to supply fuel during urgent load shedding. (As will be described in detail later, in this embodiment where the lines 13 and 11 are used together, the line 15 may be started to supply fuel after the initial fuel supply from the accumulator 5 is completed, so the valve (CV-2 ) 16 is opened, the valve (V-2) 9 of the line 15 is stopped.In other words, at point Y in FIG. The flow control valve (CV-
2) The valve 16 is opened by the same command issued to the stop valve (V-2) 9).

According to this embodiment, by providing the accumulator 5, it is possible to quickly achieve responsiveness when switching from gas main fuel to auxiliary liquid fuel such as light oil, and the above-mentioned delay time until pump start-up can be achieved. can solve the problem. In addition, the gasifier 2 is designed so that a constant flow rate of auxiliary fuel that does not cause blowout is supplied to the combustor 1 in advance.
If you set the throttle (in this example, throttle 10 in Figure 1) in advance based on the pressure of the fuel, the fuel volume of the accumulator 5, the pressure of the accumulator 5, the diameter of the supply pipe, etc., you can instantly open and close the valve by simply opening and closing the valve. Moreover, reliable flow control becomes possible. In other words, adjustment using a flow control valve (valve 9 in FIG. 1, etc.) is difficult to control and has problems with responsiveness, but the above settings allow easy auxiliary fuel supply without the need for such valve control. It is possible to do this.

The power plant in this example also controls the flow rate of its own coal gasification gas using a sequence control method of ON-OFF valves and pumps. Further, the flow rate control of light oil as auxiliary liquid fuel is similar, and a line 19 is provided from the coal gasifier 2 to the accumulator 5 via the valve (CV-3) 17.
The configuration is such that pressure for feeding light oil into the light oil line 11 is obtained from the gasifier 2 by opening the gas oil line 11 . That is, when the valve 17 is opened when auxiliary fuel is required, the coal gasification gas is sent from the gasifier 2 to the accumulator 5, and the auxiliary liquid fuel (light oil) is sent from the accumulator 5 by the gas pressure thus provided.
is provided to the combustor 1 via line 11.

Next, a fuel operation and control method in this power plant will be explained using FIGS. 2 and 3.

First, the case of ignition and start-up will be described.

When igniting and starting up the combustor 1, the gasifier 2
The project will not use gasified coal fuel, but will use light oil (also used as auxiliary liquid fuel during load shedding). Light oil is supplied into the combustor 1 from the fuel tank 22 by the pump 6 through the line 15. The flow rate is adjusted by a control valve (CV-2) 16 located on the line 15. Second
As shown by the broken line in the figure, when the load reaches about 5% (point A in Figure 2), the light oil fuel decreases and instead the coal gasification fuel shown by the solid line is supplied. This is supplied from the gasifier 2 to the combustor 1 through the gasified fuel line 8 in FIG. The control by this valve 7 is shown in Fig. 2B.
This is done up to the rated load of the point.

In this way, at the time of ignition, light oil with a stable flame is used, and coal gasification gas is supplied while light oil is being supplied, so the combustion of the gasified fuel, which is the main fuel, is carried out stably and the start-up is completed. .

During the operation of the pump 6 at this start-up, the stop valve (V-1) 2 is opened to store light oil in the accumulator 5. There is a check valve 1 in the light oil line 13.
4 is provided to prevent backflow even if the pump 6 is stopped. When the required amount of light oil is supplied to the accumulator 5 in this way, the stop valve (V-1)
12 is closed.

This concludes the explanation of the operation during ignition and start-up. Next, the operation during load shedding will be explained.

During normal operation, the load shedding signal 2 is sent from the generator 21.
Consider the case where 5 is issued. When the generator 21 issues a load shedding signal during normal operation, the turbine 4 and the generator 21 are first shut off, and the load control device 24 that has received the load shedding signal 25
outputs a command signal 25a to the flow control valve (CV-1) 7 of the gasified gas fuel supply line 8, and this valve (CV-1) 7 is immediately throttled. That is, the load shedding signal 25 was issued at point C in FIG. It is narrowed down to point E. Thereafter, as shown in the figure, the valve 7 is completely closed and the gas fuel supply is stopped.
Such main fuel control is to prevent the turbine 4 from overspeeding.

On the other hand, the command signal 25a is applied to the valve (CV-1) 7.
At the same time, that is, at point C, the stop valve (V-2) 9 of the supply line 11 of light oil fuel, which is auxiliary liquid fuel, and the stop valve (V-3) of the pressure supply line 19 to the accumulator 5 are activated. 17
In both, command signals 25b and 25c are output, respectively. This opens each valve 9, 17. Therefore, the auxiliary fuel (light oil) in the accumulator 5 is instantaneously supplied to the combustor 1. Gas pressure is applied from the gasifier 2 through the valve 17, and the valve 9 opens at the same time, so that the pressure causes the auxiliary fuel to flow through the valve 9, through the light oil supply line 11, and immediately into the combustor 1.
This is because it is sent to

As shown in FIG. 2, auxiliary liquid fuel (light oil) instantly flows at point C and is supplied to the combustor 1.

It is assumed that the pressure of the gasifier 2 is used to send auxiliary fuel (light oil) to the combustor 1 without particularly adjusting the flow rate of the fuel. Further, the maximum flow rate of fuel is limited by a throttle 10 provided in the line 11. This is as described above.

Based on the cutoff signal 25, the load control device 24 also outputs a command signal 25d to the pump 6 at the same time. As a result, the pump 6 starts operating at time C as shown in FIG. While the auxiliary fuel is being supplied from the accumulator 5, the pump pressure reaches a predetermined pressure. This is point D in FIG. 3, and this point is also shown in FIG.

After the pump pressure reaches a predetermined value, the direct line 15 is used. This line 15 was used at the time of ignition and start-up. It is also possible to open the valve (V-4) 12 of the line 13 and supply fuel to the combustor 1 through the accumulator 5 and the supply line 11 without using this, but at this point the fuel in the accumulator 5 has already been Since the pressure is equal to the pressure of the gasifier 2, in order to supply fuel to the accumulator 5, the pressure of the pump 6 must be increased above that pressure, which requires more power. Therefore, in order to reduce this power, the line 15 used for ignition and start-up is used instead. Since line 15 is directly connected to combustor 1,
To supply fuel, it is only necessary to make the pressure in the line 15 higher than the pressure in the combustor 1, which has become low due to the reduced load. Therefore, the power of the pump 6 can also be saved compared to using the supply system of lines 13 and 11.

At this time, at point D in FIGS. 2 and 3, when the pump 6 reaches a predetermined pressure, the command signal 25e (FIG. 1) opens the flow control valve (CV-2) 16, and the line 15 auxiliary fuel is supplied to the combustor 1. In other words, the load control device 24 issues a command signal 25e based on the cut-off signal 25, but with a time delay between CD in the figure from the input point of the signal 25, and sends this to the flow control valve (CV-2).
Output to 16. At the same time, the same command signal is also output to the stop valve (V-2) 9, which closes and the fuel supply from the accumulator 5 via the line 11 is stopped. This command signal 25e is also output to the valve (V-3) 17, and the valve 17 closes.
Stop the driving gas supply from the gasifier.
A time delay relay circuit 23 is used to generate a signal with a time delay between CDs.

With the above configuration, even when the load is cut off, the auxiliary fuel can be instantly sent to the combustor 1, combustion stability can be maintained, and blowout etc. can be reliably prevented. This is because the auxiliary liquid fuel stored in advance in the accumulator 5 is directly supplied to the combustor 1. Therefore, as described above, there is no need to wait for the elapse of time until the pump 6 starts up, so this is a perfect measure against load interruption.

In addition, in this embodiment, as the driving force for sending such stored auxiliary fuel (light oil in the accumulator 5) to the combustor 5, this operation is performed using a pressure source, particularly gas pressure from the coal gasifier 2. As a result, instantaneous fuel supply can be achieved reliably and the device is simple.

Further, in this example, the throttle 10 is set to the pressure of the gasifier 2,
The fuel volume of the accumulator 5, the accumulator pressure, the diameter of the supply pipe, etc. are set appropriately in advance, and the light oil fuel flow rate is supplied to the combustor 1 at a constant flow rate to the extent that the flame does not blow out. be. Therefore, the flow rate control of the auxiliary fuel can be achieved instantaneously and with a high degree of reliability simply by opening and closing the valve, without using a flow control valve that is particularly difficult to respond and control.

In this example, the flow rate control of gasified gas from the gasifier 2 of the power plant itself and the flow rate of auxiliary fuel (light oil) are also controlled by sequence control of ON/OFF of various valves and pump 6. The control method is relatively simple and easy to control.

Moreover, in this example, the power of pump 6 is also used,
After the pump 6 starts up, the line 15 is used to directly supply fuel to the combustor 1 instead of supplying fuel from the accumulator 5, which also has a power saving effect.

In the above-described embodiment, the pressure of the gasifier 2 is used as the drive source for supplying the stored auxiliary fuel, but other pressure sources may be provided.
For example, as schematically shown in FIG. 5, a compressed air storage tank 2' is provided in place of the line 19 in the example of FIG. 1 and connected to the accumulator 5;
The fuel in the accumulator 5 is fed into the combustor 1 using high-pressure compressed air.

As mentioned above, in the coal gasification technology of the present invention, auxiliary liquid fuel is stored in advance, and at the time of load shedding, this auxiliary liquid fuel is supplied to the combustor of the gas turbine to suppress the flame in the combustor at the time of load shedding. Since the fuel is stabilized, fuel control during dumping of the gas turbine is simple, and there is an effect that blow-out does not occur at that time. In addition, it can be configured to perform control with excellent responsiveness, which is also advantageous.

Note that, as a matter of course, the present invention is not limited to the above-described embodiments.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the coal gasification power plant of the present invention. Figures 2 and 3 are diagrams explaining the operation of this example and showing its control method. Figure 2 is a graph showing the relationship between each fuel and time, and Figure 3 shows the operation of each component. It is a diagram.
FIG. 4 is a diagram illustrating the time delay for startup. FIG. 5 is a schematic illustration of a modification of the above example. DESCRIPTION OF SYMBOLS 1... Combustor, 2... Coal gasification furnace, 4... Gas turbine, 5... Accumulator, 6... Drive means (pump), 10... Throttle, 21... Generator, 22... Fuel tank.

Claims (1)

[Scope of Claims] 1. In a coal gasification power generation method in which a gas turbine is driven by fuel gas supplied from a coal gasifier to generate electricity, auxiliary liquid fuel is stored in advance, and the auxiliary liquid fuel is used when the load is cut off. 1. A coal gasification power generation method characterized in that the flame in the combustor is stabilized during load shedding by supplying the combustor to the combustor of a gas turbine. 2. The coal gasification power generation method according to claim 1, wherein the flow rate of the main fuel gas from the coal gasifier is reduced during load shedding. 3. The coal gasification power generation method according to claim 1 or 2, wherein the auxiliary liquid fuel is stored in a fuel tank and is sent to the combustor by a driving means when the load is cut off. . 4. The coal gas according to claim 3, wherein the auxiliary liquid fuel supplied from the fuel tank to the combustor is sent through a line that supplies initial auxiliary fuel to the combustor at the time of ignition and start-up. Chemical power generation method. 5. A patent claim characterized in that the auxiliary liquid fuel is stored in an accumulator and is supplied to the combustor by actuation by gas pressure from the coal gasifier or other pressure source at the time of load cutoff. The coal gasification power generation method according to scope 1 or 2. 6. The coal gasification power generation method according to claim 5, wherein the flow rate of the auxiliary liquid fuel supplied from the accumulator to the combustor is controlled by a throttle along the way. 7. There are two types of auxiliary liquid fuel: one stored in a fuel tank and one stored in an accumulator.The accumulator supplies fuel immediately when the load is cut off, and then fuel supply from the fuel tank starts. 3. The coal gasification power generation method according to claim 1 or 2, characterized in that the method is applied to the delay time until the end of the process. 8. The coal gas according to claim 7, wherein the auxiliary liquid fuel supplied from the fuel tank to the combustor is sent through a line that supplies initial auxiliary fuel to the combustor at the time of ignition and start-up. Chemical power generation method. 9 Claims characterized in that the auxiliary liquid fuel stored in the accumulator is supplied to the combustor by actuation by gas pressure from the coal gasifier or other pressure source at the time of load cutoff. The coal gasification power generation method according to item 7 or 8. 10. The coal gasification power generation method according to any one of claims 7 to 9, characterized in that the flow rate of the auxiliary liquid fuel supplied from the accumulator to the combustor is controlled by a throttle along the way. . 11 The auxiliary liquid fuel stored in the accumulator is supplied from a fuel tank, and in addition to a line from the fuel tank to the combustor via the accumulator, a line is provided that connects the fuel tank directly to the combustor. 11. The coal gasification power generation method according to any one of claims 7 to 10, wherein the power for supplying fuel from the fuel tank to the combustor after the accumulator is operated is reduced. 12. The coal gasification power generation method according to any one of claims 1 to 11, wherein the auxiliary liquid fuel is light oil. 13 In a coal gasifier power plant equipped with a coal gasifier and a gas turbine that is driven by fuel gas supplied from the coal gasifier to generate electricity, auxiliary liquid fuel is stored in advance in a fuel tank and an accumulator. Then, at the time of load shedding, auxiliary liquid fuel is immediately supplied from the accumulator to the combustor of the turbine, thereby making up for the delay time until the start of fuel supply from the fuel tank, and with this configuration, the combustion at the time of load shedding. A coal gasification power plant characterized by stabilizing the flame in the vessel. 14. The coal gasification power plant according to claim 13, wherein the flow rate of the main fuel gas from the coal gasifier is reduced during load shedding. 15. Claim 13 or 14, characterized in that the auxiliary liquid fuel supplied from the fuel tank to the combustor is sent through a line that supplies initial auxiliary fuel to the combustor at the time of ignition and start-up. Coal gasification power plant described. 16 Claims characterized in that the auxiliary liquid fuel stored in the accumulator is supplied to the combustor by actuation by gas pressure from the coal gasifier or other pressure source at the time of load cutoff. The coal gasification power plant according to items 13 to 15. 17. The coal gasification power plant according to any one of claims 13 to 16, wherein the auxiliary liquid fuel supplied from the accumulator to the combustor is flow-controlled by a throttle along the way. . 18 The auxiliary liquid fuel stored in the accumulator is supplied from a fuel tank, and in addition to a line from the fuel tank to the combustor via the accumulator, a line is provided that connects the fuel tank directly to the combustor. 18. A coal gasification power plant according to any one of claims 13 to 17, wherein the power for supplying fuel from the fuel tank to the combustor after the accumulator is operated is reduced. 19. The coal gasification power plant according to any one of claims 13 to 18, wherein the auxiliary liquid fuel is light oil.