JPS59134331A - Method of and device for controlling slide pressure operation of pressurized coal gasification type power plant - Google Patents

Abstract

PURPOSE:To reduce the required power for a gas turbine, by providing a coal gasifying furnance control device on which a sliding pressure mode is previously set, in a pressurized coal gasifying furnace so that the pressure of fuel supply to a gas turbine is automatically controlled upon partial load operation to carry out a sliding pressure operation. CONSTITUTION:An oxygen/coal ratio control device 30 for controlling an oxygen compressor 44 compensates the flow rate of oxygen in accordance with signals from an oxygen pressure gauge 45 for detecting variations in pressure, a flow meter 32 and a coal supply amount control device 24. A fuel flow adjusting valve 19 at the inlet of a gas turbine 12 maintains its opening degree constant upon partial load operation, and the flow rate of gas produced in a coal gasifying furnace decreases since the gas volume increases in association with the lowering of gas pressure. Accordingly, the output power of the gas turbine 12 varies in association with variations in the flow rate of gas produced in the gas furnace. With this arrangement, a required power for the compressor may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for controlling variable pressure operation of a coal gasifier during partial load in a pressurized coal gasification combined cycle power plant, and a control device thereof.

[Prior art]

FIG. 1 is a system configuration diagram showing an example of a coal gasification combined cycle power plant.

Coal 2 is supplied to the gasifier 3 from a coal supply facility 1, and at the same time, oxygen 5 as a coal gasifying agent is supplied from an oxygen supply facility 4. In the gasifier 3, coal and oxygen react, and a composition gas 6 is generated. The composition gas 6 is cooled by a gas cooling facility 7 and generates steam 8. The cooled composition gas 9 is sent to a gas purification facility 10, where it is dedusted and desulfurized to become a purified gas 11.

The purified gas 11 is sent to the gas coupin 12 of the combined power generation facility, where it is combusted to drive a turbine and generate electricity. The gas after being combusted and driving the turbine is a high-temperature exhaust gas 13
The waste heat is sent to the exhaust heat recovery boiler 14 as waste heat recovery boiler 14. High temperature exhaust gas 1
The heat is recovered as steam by an exhaust heat recovery boiler 14, and is discharged as relatively low temperature exhaust gas 34. The steam generated in the exhaust heat recovery boiler 14 and the steam 8 from the gas cooling 7 are
It is superheated in the exhaust heat recovery boiler 14 and sent to the steam turbine 16 as superheated steam 15. Superheated steam 15 drives a steam turbine 16 to generate electricity.

An example of a conventional method of operating a coal gasification combined cycle power plant will be explained with reference to FIG.

A load request signal 17 from the central controller 70 is input to the gas turbine controller 18, and the gas turbine controller 18 opens and closes the fuel flow rate regulating valve 19 according to the requested load to control the fuel flow rate. The output of the turbine 12 is controlled.

On the other hand, a set pressure 20 at the gas purification outlet is set in the central controller 70, and this set pressure 20 at the gas purification outlet is set to a constant pressure regardless of the load of the plant.

The pressure of the gas purification equipment 10 is determined by a pressure signal 22 from a pressure gauge 21.
is sent to the gas purification pressure control device 23 as
A signal 25 indicating an increase or decrease in the coal supply amount is sent to the coal supply amount control device 24 based on the difference from the fixed value).

The coal supply amount control device 24 is the gas purification pressure control device 23
and the signal 27 from the coal flow meter 26,
A signal 29 is sent to the coal supply amount adjustment valve 28 to increase or decrease the amount of coal supplied.

The amount of oxygen supplied is still controlled by the oxygen/coal ratio controller 330. The oxygen/coal ratio control device 30 receives coal supply amount and
A signal of the amount of oxygen supplied is sent. Oxygen/coal ratio control device 3
0, the oxygen supply amount is adjusted by the oxygen supply amount adjustment valve 33 so that the ratio of the coal and oxygen supply amounts is constant.

In the example shown in Figure 2, the pressure at the gas purification outlet is controlled to be constant, and this is at rated load.

It is always kept constant regardless of partial load. therefore,
Even during partial load, the pressure in the gasifier 3 only decreases by the amount of pressure loss due to the decrease in the flow rate of the composition gas, and is not much different from the pressure at rated load.

Another example of the conventional operating method is shown in FIG.

The difference from the example in Figure 2 is that in the example in Figure 2, the load request signal 1
7 is input to the gas turbine side, and the set pressure signal 20 of the gas purification equipment is input to the gasifier side, whereas in the example of Fig. 3, the load request signal 17 is input to the gasifier side, and the gas purification equipment The set pressure signal 20 is input to the gas turbine side. The example in Figure 2 is a gas turbine-driven type where the gasifier follows the gas turbine, whereas the example in Figure 3 is a gasifier-driven type where the gas turbine follows the gasifier. It has become.

Although there is a difference between gas turbine-driven and gasifier-driven systems, in the example in Figure 3 as well as in the example in Figure 2, the outlet pressure of the gas purification equipment is controlled to be constant regardless of the plant load. ing.

As explained above with reference to examples, the conventional method of operating a coal gasification combined cycle power plant is carried out by keeping the pressure of the fuel gas required by the gas turbine constant. Conventionally, constant pressure operation control as described above has been performed mainly for control technology reasons.
As will be described later, it is uneconomical to maintain the same gas pressure as during rated operation even during partial load operation in terms of energy loss spent on gas compression.

Figure 4 is a diagram showing the state in which oxygen as a gasifying agent is sent out from a compressor and then sequentially passed through a gasification furnace, an exhaust heat recovery boiler, etc. to reduce its pressure. This pressure is equal to the rated pressure at the outlet of the pressure regulating valve by 1
It is expressed as 00%.

The gasifier pressure 35 during rated operation shown by the solid line is the gas turbine combustor inlet fuel pressure 36 during rated operation, the reduced pressure at the gas turbine fuel flow pressure regulating valve, the pressure regulating valve, gas purification equipment, and heat recovery. The pressure is the sum of pressure loss in systems such as boilers. The oxygen discharge pressure 37 during rated operation is the gasifier pressure 35 during rated operation plus some pressure.

The dashed curve 38 shows the gas pressure during 50 inch part load operation in the conventional method of controlling the gas pressure to keep it constant as described above.

The inlet pressure of the gas turbine combustor at the rated time is the pressure represented by point 36, while at 50% load it is the pressure represented by point 39. However, as described above, since the control method is to maintain the gas pressure constant even during partial load, the excess pressure P is reduced and used by the gas turbine fuel flow rate pressure regulating valve.

In other words, when the gas purification equipment outlet pressure is kept constant, the gas flow rate is half of the rated operation, which reduces the pressure loss in the heat recovery boiler and the gas purification equipment, so the gasifier pressure 38 remains at the rated operation. The pressure will also be slightly lower. The gas turbine combustor inlet fuel pressure 39 during partial load operation is much lower than the pressure 36 during rated operation, so the gas turbine fuel flow pressure regulating valve does not have to reduce the pressure much more than during rated operation. It is uneconomical.

On the other hand, if only the pressure drop is considered without throttling the valve to reduce the pressure between the gasifier and the gas turbine combustor inlet during partial load, the pressure in the gasifier will be 40 As shown in Figure 2, the oxygen discharge pressure in this case is sufficient to be the pressure represented by point 41.Comparing this with the conventional control method, the oxygen pressure 42 during conventional partial load operation is determined by heat recovery. Compared to the oxygen pressure 41 determined only by the pressure loss of the boiler, gas purification equipment, pressure regulating valve, and gas turbine fuel pressure regulating valve, the pressure is higher by the amount indicated by diagonal lines.

The pressure difference shown by diagonal lines between the two is the amount where the oxygen pressure is increased more than necessary, which means that the power of the oxygen compressor is used excessively, and this causes a loss in sybrant efficiency. Particularly in coal gasification combined cycle power generation plants, the ratio of the power of the oxygen compressor to the final power generation output is as high as about 10%, so reducing the power of the oxygen compressor leads to a significant improvement in plant efficiency.

[Purpose of the invention]

The present invention has been made based on the above-mentioned considerations, and its purpose is to reduce the pressure of the pressurized coal gasifier to the fuel required by the gas turbine during partial load operation of a pressurized coal gasification combined cycle power plant. By lowering the gas pressure to the lowest pressure that can be supplied and performing variable pressure operation of the pressurized coal gasifier, the power required for the oxygen compressor that supplies oxygen to the gasifier can be reduced, improving plant efficiency. It is an object of the present invention to provide a transformer type control method and a transformer type control device that can contribute to the present invention.

[Summary of the invention]

In order to achieve the above object, the control method of the present invention applies a pressurized coal gasification furnace, a gas purification facility, a combined power generation facility including a gas turbine, and a pressurized coal gasification facility such as a gasification agent supply facility. In a combined cycle power generation plant, a gasifier control device is installed with a pressure transformation mode set in advance, a load request signal is input to this gasifier control device, and the gasifier control device is used to control coal supply equipment and gas north side compressor. The present invention is characterized in that a command signal corresponding to the load is given to the gas turbine to automatically control the fuel supply pressure of the gas turbine during partial load operation to perform variable pressure operation.

Furthermore, in order to easily implement the above-mentioned control method and fully exhibit its effects, the control device of the present invention is applicable to pressurized coal gasifiers, gas purification equipment, combined power generation equipment including gas turbines, and gas turbines. In a pressurized coal gasification combined cycle power plant that is similar to a delta agent supply facility, a gasifier control device configured to be able to set a -transforming mode is provided, and
A load signal is input to the gasifier control device as described above, and the gasifier control device provides a signal of the coal supply amount according to the load to the coal supply equipment, and also to the gas north side compressor. It is characterized in that it is configured to give a signal of the gas north side flow rate according to the load.

[Embodiments of the invention]

FIG. 5 is an explanatory diagram of one embodiment of the method and apparatus of the present invention.

The load request signal 17 from the central controller 70 first enters the gasifier controller 43. The gasifier control device 43 includes
The oxygen pressure, oxygen compressor rotation speed, and coal supply amount are set according to the load, and the oxygen compressor 4 is adjusted according to the load request.
42 Coal Sends a signal to the coal supply amount adjustment valve 4.

The coal supply amount control device 24 sends a signal to increase or decrease the coal supply amount to the coal supply amount adjustment valve 28 based on the coal supply amount signal from the gasifier control device 43 and the signal from the coal flow meter 26 .

The amount of oxygen supplied to the gasifier is controlled by an oxygen/coal ratio controller 30.
controlled by An oxygen pressure gauge 45, an oxygen flow meter 32, and a coal supply amount control device 2 are connected to the oxygen/coal ratio control device 30.
The oxygen/coal ratio controller 30 sends signals to the oxygen compressor 44 to increase or decrease the oxygen supply based on these three signals which correct the flow meter readings due to pressure changes.

The oxygen compressor 44 is controlled by an oxygen supply amount signal from the oxygen/coal ratio control device 30 and an oxygen pressure signal from the gasifier pressure control device 43. The oxygen compressor 44 is driven by a steam turbine (not shown), and adjusts the flow rate and pressure of oxygen by controlling the rotation speed of the compressor. In addition, if the oxygen compressor is driven by a motor, the rotational speed of the compressor is controlled by silisk control or by using a fluid coupling or the like, or the flow rate is controlled by vanes.

The fuel flow rate regulating valve 19 at the inlet of the gas turbine 12 maintains a constant valve opening under partial load, and the flow rate of the gas generated in the gasifier increases in specific volume and decreases as the gas pressure decreases. Therefore, the output of the gas turbine 12 changes depending on the change in the flow rate of the gas generated in the gasifier.

FIG. 6 is an explanatory diagram of an embodiment different from the above.

Compared to the previous example, in this example, a fuel gas pressure correction signal line from the gasifier pressure control device 43 to the gas turbine control device 18 is added, and the gas turbine inlet fuel pressure is finely adjusted by this signal. This makes it possible to respond to sudden load changes.

In addition, no oxygen flow meter will be installed, and the oxygen flow rate will be calculated based on the pressure of the oxygen pressure gauge.

Figure 7 shows the relationship between the flow rate, efficiency, pressure, and shaft power of the oxygen compressor. Generally, there are two ways to control the fuel pressure and flow rate of a gas turbine: one is to restrict the nozzle area using a pressure regulating valve, and the other is to keep the nozzle area constant and change the pressure. The present invention performs the latter variable pressure operation, but instead of adjusting the gas pressure with a pressure regulating valve at the outlet of the gas purification equipment, the fuel pressure and flow rate of the gas turbine are controlled by the coal supply amount and the oxygen gas compressor discharge pressure. control.

In the case of constant pressure in the gasifier, the relationship between flow rate and pressure when the discharge valve is throttled is as shown by curve 46 in this figure, and in the case of vane control, it is shown by curve 47.

On the other hand, in the case of gasifier variable pressure, the relationship between flow rate and pressure becomes curve 48 when vane control or compressor rotation speed control is used. Here, the oxygen pressure required in the gasifier is the pressure shown in 47 in the case of a constant pressure gasifier,
In the case of a gasifier with variable pressure, the pressure shown in 48 shall be used. Therefore, compared to the gasifier constant pressure, in the case of the gasifier variable pressure, 4
The pressure difference between the pressure of 7 and the pressure of 48 is the pressure that can be reduced in the oxygen compressor.

The efficiency of the compressor becomes a curve shown at 49 when the number of revolutions is constant, and a curve shown at 50 when the number of revolutions is varied. From the relationship between 49 and 50 in FIG. 7, it can be seen that controlling the efficiency of the compressor by changing the rotation speed is better than controlling the compressor by controlling the rotation speed at a constant speed using vanes, discharge valves, etc.

The shaft power shows a curve 51 when the gasifier has constant pressure, constant compressor rotation speed, and discharge valve throttle, and a curve 52 when the gasifier has constant pressure, constant compressor rotation speed, and vane control. , the curve 53 is the case with variable gasifier pressure, constant compressor rotation speed, and vane control, and the curve 54 is the case with variable gasifier pressure and constant compressor rotation speed control. As can be seen from FIG. 7, the magnitude of the shaft power decreases in the order of 51, 52, 53.54, and is the smallest in the case of gasifier pressure change/compressor rotation speed control.

Summarizing the above-mentioned effects, the power consumption of the gas compressor (curve 54) when variable pressure operation is controlled by the method of the present invention using the device of the present invention is equal to the power consumption of the gas compressor in the prior art (curve 52). In comparison, it is reduced by the amount shown with diagonal lines.

An example of the effect of reducing the power of the oxygen gas compressor on improving the efficiency of the entire power plant will be described below with reference to FIG.

The vertical axis on the left side of this chart represents the relative efficiency improvement as a percentage, and the vertical axis on the right side represents the consumption rate within the idle plant (in-plant rate) relative to the final power generation output as a negative percentage. The horizontal axis is the generator load factor.

The in-house rate of the oxygen compressor in the conventional constant pressure operation method is the curve 57, but by applying the present invention, the in-house rate is the curve 5.
It changes like 8. Therefore, the shaded area represents the reduction in the on-site ratio. As a result, the efficiency of the entire power plant improves by the amount shown by curve 59. As is clear from the principle of operation of the present invention, the present invention does not cause any inefficiency improvement under rated load, but noticeably improves efficiency under low load conditions. Curve 55 is the in-house rate of the raw air compressor, and curve 56 is the in-house rate of equipment other than the raw air compressor and the oxygen compressor.

〔Effect of the invention〕

As described in detail above, the variable pressure operation control method of the present invention provides a pressurized coal gasification complex comprising a pressurized coal gasifier, a gas purification facility, a combined power generation facility including a gas turbine, and a gas north side supply facility. A power generation plant is equipped with a gasifier control device that has been set to a transformer mode in advance, and a load request signal is input to this gasifier control device, and the gasifier control device controls the coal supply equipment and gasifier compressor. By giving a command signal according to the load and automatically controlling the fuel supply pressure of the gas turbine during partial load operation to perform variable pressure operation, This greatly contributes to reducing power consumption and improving plant efficiency.

Further, the variable voltage operation control device of the present invention is applicable to a pressurized coal gasification combined cycle power generation plant comprising a pressurized coal gasification furnace, gas purification equipment, combined power generation equipment including a gas turbine, and gas north side supply equipment. In addition to providing a gasifier control device configured to be able to set the pressure transformation mode, it is also possible to input a load signal to the gasifier control device. The above-described method of the present invention is achieved by configuring the supply equipment to give a signal of the coal supply amount according to the load, and to give the gasifier compressor a signal of the gas north side flow rate according to the load. can be easily implemented and its effects can be fully demonstrated.

[Brief explanation of drawings]

Figure 1 is a system configuration diagram of a coal gasification combined cycle power plant, Figures 2 and 3 are explanatory diagrams of the operating method of a conventional coal gasification combined cycle power plant, and Figure 4 is a diagram of each of the coal gasification combined cycle power plants. The charts showing the gas pressure in the equipment, FIGS. 5 and 6, respectively show one embodiment of the method and control device for controlling the variable pressure operation of the pressurized coal gasification combined cycle power plant and the variable pressure operation of the gasification combined cycle plant of the present invention. FIG. 7 is a chart showing the relationship between flow rate, pressure, efficiency, and shaft power of the oxygen compressor, and FIG. 8 is a chart for explaining the present invention in detail. 19...Fuel flow rate control valve, 26...Coal flow meter, 2
8... Coal supply amount adjustment valve, 31... Coal flow meter, 3
2...Oxygen flow meter, 33...Oxygen supply amount adjustment valve. Agent Patent attorney Masamiyoshi Akimoto 7 Mekyo 8 Written amendment to oral proceedings (spontaneous) January 1, 1932 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case Showa sty 2006 Special Patent hjj 4 No. 7363 2. Title of the invention. Variation voltage operation control method and device for a pressurized coal gasification combined cycle power plant 3, person making the correction A] - Place (residence) Hitachi Engineering Co., Ltd. 4, Agent (1) Detailed explanation of the invention, page S Procedural amendment to delete "3" at the end of line j (voluntary) ji + January 10, 1939, Commissioner of the Japan Patent Office, Mr. Hiroo Wakasugi, 16 Indication of the case Showa SG Patent Application No. 73t3 No. 3, amendment Address of person (residence) Hitachi Kou/Sonia Ring Co., Ltd. 4, Agent

Claims (1)

[Claims] 1. In a pressurized coal gasification combined power generation plant including a pressurized coal gasification furnace, gas purification equipment, combined power generation equipment including a gas turbine, and gasifying agent supply equipment, A gasifier control device set to a pressure transformation mode is provided, a load request signal is input to the gasifier control device, and the gasifier control device controls the load on the coal supply equipment and gasifier compressor. A variable pressure operation control method for a pressurized coal gasification combined cycle power plant, characterized in that the fuel supply pressure of a gas turbine is automatically controlled during partial load operation by giving a corresponding command signal to perform variable pressure operation. 2. It is now possible to set the pressure transformation mode in a pressurized coal gasification combined cycle power generation plant consisting of a pressurized coal gasification furnace, gas purification equipment, combined cycle equipment including a gas turbine, and gasifying agent supply equipment. In addition to providing the configured gasifier control device, a load signal can be input to the gasifier control device, and the gasifier control device can supply coal to the coal supply equipment according to the load. A variable voltage operation control device for a pressurized coal gasification combined cycle power plant, characterized in that it is configured to give a signal of the amount of gasifying agent and also give a signal of the gasifying agent flow rate according to the load to the gasifying agent compressor. 3. The rotational speed of the gasifier compressor is automatically controlled in response to a command signal from the gasifier controller and a command signal from the gasifier/coal ratio controller. The second claim is characterized in that
2. A variable voltage operation control device for a pressurized coal gasification combined cycle power plant as described in 2.