JPH11117711A - Gasification compound power generation plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plant having a configuration by which the plant can be operated so that the thermal efficiency is maximum in response to the operating state of the plant, in the gasification compound power generation plant. SOLUTION: In a gasification compound power generation plant which is provided with a compressor 15, a mechanism for extracting a part of discharge air from the compressor, a gas turbine 5 having a combustor 14 for supplying the compressordischarge air, nitrogen and fuel, and burning them, and a turbine 16, an oxygen manufacturing facility 1, a gasification device for generating flammable gas from coal, etc., using oxygen, or a mixture of oxygen and air, and a heat exchanger 9 for heat-exchanging the air extracted from the compressor 15 for nitrogen separated at the oxygen manufacturing facility 1, and which supplies the gas turbine combustor 14 with nitrogen after heat exchange, and flammable gas, equipment 17 for controlling the extracted air quantity so that the thermal efficiency is maximum in response to the state of the gasification compound power generation plant, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated gasification combined cycle power plant equipped with a device for controlling the amount of air extracted from a gas turbine.

[0002]

2. Description of the Related Art In a conventional integrated gasification combined cycle power plant, only an operation during a transition period from a single operation of a raw air compressor at the time of startup to a supply operation of bleed air of a gas turbine compressor is performed.
The control of the bleed air amount by operating the bleed air flow valve is not performed (conventional example 1, JP-A-8-158890). Further, the control of the amount of extracted air to maximize the thermal efficiency according to the state of the integrated gasification combined cycle power plant has not been performed yet.

[0003] As an example of a conventional integrated gasification combined cycle power plant, Fig. 2 shows a general system configuration using compressor bleed air for cooling a turbine. This figure is a schematic diagram showing the flow of fuel and gas when an oxygen-blown coal gasifier is used as a gasifier and a wet gas purifier is used as a gas purifier. Water and steam flows are omitted. Hereinafter, the integrated gasification combined cycle power plant will be described with reference to FIG.

[0004] The oxygen production equipment 1 pressurizes air 20 as a raw material with a compressor, and takes in pressurized air obtained by adding bleed air 26 from the gas turbine 5 to oxygen gas and nitrogen gas containing a small amount of impurities. Decompose into The oxygen gas and the nitrogen gas are pressurized by a compressor for use in a gasifier, a gas turbine, or the like, and output as oxygen 21 and nitrogen 22. In this figure, the whole of the air separation process plus the compressor for pressurization is simplified and shown as the oxygen production equipment 1. The coal 23 is dried by the coal dryer 11 and supplied to the gasifier 2. Gasifier 2 is about 20-3
Under the pressurization of 0 atm, the gasification process of coal is carried out by taking in oxygen 21 as an oxidizing agent, and at the same time, a part of coal as fuel is burned. The heat generated in the gasifier 2 and the heat of the generated gas are absorbed by the gasifier cooling heat exchanger and the heat recovery boiler 3, and the steam generated thereby is generated in the exhaust heat recovery boiler 8. In addition to the steam, the steam is further converted into superheated steam to form a steam turbine 6
Sent to Thereby, about 110 at the outlet of the gasifier 2
The generated gas temperature of 0 ° C is 400 ° C at the outlet of the heat recovery boiler 3.
It is cooled to about 200 ° C. or less by gas / gas heat exchange 13 and sent to a wet gas purification facility 4. The generated gas 24 is dedusted and desulfurized in the gas refining facility 4, and the gas temperature is once reduced to about normal temperature in the refining process. The temperature recovers to become purified gas 25. In addition,
When the gas purification equipment 4 uses a dry high-temperature gas purification process, the gas temperature becomes a high temperature of about 500 ° C. or more, and the sensible heat loss of the produced gas is considerably reduced. The purified gas 25 is sent to the combustor 14 together with the by-product nitrogen 22 obtained from the oxygen production facility 1 heated by the heat exchanger 9. Purified gas 2
5 and the heated nitrogen 22 are mixed into the combustor 14 or mixed in the combustor 14 to form a fuel gas having a relatively low calorific value, and the compressed gas sent from the compressor 15 of the gas turbine in the combustor 14. Burned by air. The combustion gas expands in the turbine 16 to operate the gas turbine. Turbine 1
For cooling of 6, the compressed air sent from the compressor 15 of the gas turbine is extracted and the pressure is increased by the booster compressor. The compressed air is returned to the turbine through the cooling passage (open cooling system) or to the combustor. Sent (closed cooling system).
The gas turbine 5 drives the generator 7 together with the steam turbine 6 to generate electric power, and the exhaust gas 27 is sent to the exhaust heat recovery boiler 8 and discharged from the chimney after heat recovery. The temperature of the compressed air of the compressor 15 of the gas turbine rises to about 400 ° C. due to the compression (the compression ratio differs depending on the gas turbine, so it differs accordingly), and a part of the air is extracted and extracted as the heat exchanger 26 as the extracted air 26 9 The bleed air 26 exchanges heat with the relatively low-temperature nitrogen 22 having a temperature of about 100 ° C. or less in the heat exchanger 9, and is then sent to the oxygen production facility 1 to become the whole or a part of the raw air.

[0005]

The gasification combined cycle power plant has been designed so that the gas turbine pressure ratio and the output are maximized (or allowable limits). This is because when the plant thermal efficiency was surveyed using the extraction ratio (the ratio of the extraction air flow rate to the air flow rate processed by the oxygen production facility) as a parameter, the plant thermal efficiency was also maximum at the point where the gas turbine pressure ratio and output were the maximum. (When the bleed ratio was small, the amount of air flowing into the compressor was reduced by IGV (inlet guide vane) opening control, and the gas turbine output was surveyed so as to be less than the maximum (or allowable limit)).

However, in the case of operating a gasification combined cycle power plant using a gas turbine having a large pressure ratio, or in the case of performing a partial load operation due to a change in external environment (such as atmospheric temperature), the gas turbine is not necessarily used. At the point where the pressure ratio and output are at the maximum, the plant thermal efficiency is not at the maximum (FIG. 3). This is probably because heat exchange in the heat exchanger is not sufficient and energy is wasted.
Conventionally, in such a case, only the IGV opening degree control is performed. Even if the pressure ratio can be operated to be the maximum (or the allowable limit), the operation cannot be performed to maximize the gas turbine output. Was.

Therefore, it is necessary to perform control so that the gas turbine pressure ratio and the output can be maximized under any conditions, that is, the operation can be performed so as to maximize the plant thermal efficiency.

An object of the present invention is to provide a gasification combined cycle power plant that solves the above-mentioned problems.

[0009]

The above object is achieved by the following means.

According to the state of the combined gasification combined cycle power plant,
A device for controlling the bleed air flow is provided to control the bleed air flow so that the plant thermal efficiency is maximized.

Specifically, a gas having a compressor, a mechanism for extracting a part of the compressor discharge air, a combustor for supplying and discharging the compressor discharge air, nitrogen and fuel, and a turbine A turbine, an oxygen production facility for separating oxygen and nitrogen from air, and a gasification system for producing combustible gas by gasifying coal or heavy oil using the oxygen or oxygen-enriched air obtained by mixing the oxygen and air. An apparatus, comprising a heat exchanger for heat exchange between the air extracted from the compressor of the gas turbine and the nitrogen separated and pressurized in the oxygen production facility, and the nitrogen after the heat exchange is supplied to the gas turbine combustor. In the gasification combined cycle power plant that supplies and generates the combustible gas as the fuel to the gas turbine combustor, the bleed air is set so that the thermal efficiency is maximized according to the state of the gasification combined cycle plant. Characterized in that it comprises a control device.

A gas turbine having a compressor, a mechanism for bleeding a part of the compressor discharge air, a combustor for supplying and burning the compressor discharge air, nitrogen and fuel, and a turbine; An oxygen production facility for separating oxygen and nitrogen from air, and a gasifier that gasifies coal or heavy oil using the oxygen or the oxygen-enriched air obtained by mixing the oxygen and the air to generate a combustible gas, A gas exchanger for exchanging heat between the air extracted from the compressor of the gas turbine and the combustible gas generated by the gasifier, and supplying the combustible gas after heat exchange to the gas turbine combustor; The combined cycle power plant is characterized by including a device for controlling the amount of bleed air to maximize the thermal efficiency according to the state of the combined gasification combined cycle plant.

In the combined gasification combined cycle power plant according to claim 1 or 2, an apparatus for controlling the amount of extracted air so that the extracted air temperature after the heat exchange in the heat exchanger becomes a target value. It is characterized by having.

Alternatively, in the integrated gasification combined cycle plant, the state of the combined gasification combined cycle plant is input and the amount of extracted air at which the thermal efficiency is maximized is calculated by an analytical model.
An apparatus is provided for controlling a bleed air flow rate in accordance with the amount calculated by the analysis model.

If an apparatus for controlling the bleed air flow rate according to the state of the integrated gasification combined cycle power plant is provided, even if the gas turbine is operated in a state where the pressure ratio is smaller than the maximum (or allowable limit), the bleed air is controlled. By controlling the flow rate, it is possible to operate the gas turbine at the maximum (or allowable limit), and to perform sufficient heat exchange in the heat exchanger, without wasting energy held by the extracted air. As a result, the plant thermal efficiency can be kept high.

When a device for controlling the flow rate of the extracted air in accordance with the temperature of the extracted air after the heat exchange in the heat exchanger is provided, the temperature of the extracted air after the heat exchange is set by controlling the amount of the extracted air. In order to keep the value, the energy held by the bleed air need not be discarded, so that the plant thermal efficiency can be kept high.

In the case where a device for inputting the state of the gasification combined cycle power plant, calculating the amount of bleed air at which the thermal efficiency is maximized by an analytical model, and controlling the bleed air flow rate to the amount calculated by the analytical model is provided. Since the bleed air amount at which the plant thermal efficiency is maximized is calculated by the analysis model using the state that changes every moment as an input, the plant thermal efficiency can always be kept high.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram showing a first embodiment of the present invention.

This embodiment differs from the combined gasification combined cycle plant shown in FIG. 2 in that a device for controlling the amount of extracted air is added.

The reason why the flow rate of the bleed air should be controlled in the present embodiment is as follows.

In the integrated gasification combined cycle plant, the gas turbine pressure ratio and the output are designed to be maximum (or allowable limit). This is because, when the plant thermal efficiency was surveyed using the extraction ratio as a parameter, the plant thermal efficiency was also the maximum at the point where the gas turbine pressure ratio and output were the maximum (when the extraction ratio was low, the IGV (inlet guide vane) opened. The air flow rate of the compressor was reduced by degree control, and the gas turbine output was surveyed so as to be less than the maximum (or allowable limit)).

However, the plant thermal efficiency may not be maximized at the point where the gas turbine pressure ratio and the output are maximum (FIG. 3). This includes (1) the case of operating a gasification combined cycle power plant using a gas turbine having a large pressure ratio, or (2) the case of performing partial load operation when the external environment (such as the atmospheric temperature) changes. 3) The case of operating a combined gasification combined cycle power plant using a nitrogen-cooled gas turbine may be considered.

(1) When operating a gasification combined cycle power plant using a gas turbine having a large pressure ratio, the bleed air temperature rises because the pressure ratio is large, and the pressure ratio reaches a maximum (or allowable limit). Is large, the heat exchanger 9
The nitrogen temperature at the outlet reaches the temperature of the bleed air, and the thermal energy of the bleed air cannot be sufficiently recovered by nitrogen. As a result, the thermal efficiency of the plant is considered to decrease.

(2) When an external environment (atmospheric temperature or the like) changes and a partial load operation is performed, compared with the rated operation,
If the decrease in the nitrogen flow rate is greater than the decrease in the bleed air amount, the same phenomenon as (1) occurs.

(3) When operating an integrated gasification combined cycle power plant using a nitrogen-cooled gas turbine, nitrogen heated by the heat exchanger 9 is used for cooling the turbine. However, there is an upper limit to this cooling nitrogen temperature. It is considered that the heat energy of the bleed air cannot be sufficiently recovered by the heat exchanger 9, the temperature of the bleed air at the outlet of the heat exchanger 9 increases, the heat energy discarded by the oxygen production equipment 1 increases, and the thermal efficiency of the plant decreases. Can be

Conventionally, in the above case, only the IGV opening control is performed, and even if the pressure ratio can be operated to the maximum (or the allowable limit), the gas turbine output can be maximized. Could not drive.

Therefore, it is necessary to control the amount of extracted air so that the gas turbine pressure ratio and the output can be maximized under any conditions, that is, the operation can be performed so as to maximize the plant thermal efficiency.

The control of the amount of extracted air is performed in accordance with the state of the combined gasification combined cycle plant.

More specifically, the following method can be considered.

1) The temperature of the bleed air (the temperature at the point A) after the heat exchange in the heat exchanger 9 is controlled to be a target value. It is considered that by maximally recovering the heat energy of the extracted air, the plant thermal efficiency is maximized. However, as an index of the heat energy recovery of the extracted air, the extracted air temperature after the heat exchange in the heat exchanger 9 (point A) Temperature) can be considered. It is considered that if the temperature is kept low, the thermal efficiency of the plant is improved accordingly. Therefore, the bleed air temperature (point A
The temperature of the air is controlled to be a target value. In this case, at the compressor outlet of the raw material air 20 supplied to the oxygen production equipment 1, the raw material air temperature at a point (point B) before merging with the bleed air or the nitrogen temperature at the inlet of the heat exchanger 9 (point C) Is used as a reference value, and a target value may be set in accordance with the difference between the reference value and the bleed air temperature (the temperature at point A).

2) The state of the combined gasification combined cycle power plant is input, and the amount of extracted air at which the thermal efficiency is maximized is calculated and controlled by an analytical model. By using the analysis model, the plant thermal efficiency of the operating integrated gasification combined cycle power plant at that time can be analyzed with the extraction ratio as a parameter, and the control target value of the extraction air flow rate can be set from the extraction ratio at which the plant thermal efficiency becomes maximum. Can be.

Although it is possible to further improve the thermal efficiency by using the extracted air at the outlet of the heat exchanger 9 for heating the feed water in the bottoming cycle, the same operation may be performed in this case. When measuring the bleed air temperature, in addition to the bleed air temperature at the outlet of the heat exchanger 9 (the temperature at the point A), the bleed air temperature after water supply heating in the bottoming cycle is measured and used for control. It is possible.

[0034]

As described above, according to the present invention, by providing a control device for controlling the amount of extracted air, the external environment (atmospheric temperature, etc.) can be changed, partial load operation can be performed, and design can be performed. Even under conditions different from the design rated point, such as operation with fuel other than fuel, operation can be performed to maximize the plant thermal efficiency of the combined gasification combined cycle plant.

Since the gasification combined cycle power plant is configured so that the energy held by the extracted air can be recovered on the gas turbine side as much as possible, the heat recovery on the steam turbine side by heating the feed water in the bottoming cycle, etc. Also, the thermal efficiency of the plant can be improved. However, plant heat efficiency can be further improved if the steam turbine side can recover energy that cannot be completely recovered by the gas turbine even under control.

Also, since only the temperature of the extracted air at the heat exchanger outlet and the amount of the extracted air can be controlled as the state inputs of the combined gasification combined cycle plant, the control can be simplified.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

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

FIG. 3 shows a gas turbine (G
T) Pressure ratio and transmission end efficiency (H
It is a figure which shows the example of an analysis of HV).

[Explanation of symbols]

1. Oxygen production equipment 2. Gasification furnace 3. Heat recovery boiler
4 gas purification equipment, 5 gas turbine, 6 steam turbine, 7 generator, 8 heat recovery boiler, 9 heat exchanger,
DESCRIPTION OF SYMBOLS 11 ... Coal dryer, 12 ... Steam drum, 13 ... Gas / gas heat exchange, 14 ... Combustor, 15 ... Compressor, 16 ... Turbine, 17 ... Extraction control device, 20 ... Air, 21 ... Oxygen, 2
2 ... nitrogen, 23 ... coal, 24 ... product gas, 25 ... purified gas, 26 ... bleed air.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02C 7/08 F02C 7/08 Z 9/18 9/18 9/52 9/52 F23L 7/00 F23L 7/00 A B F25J 3/04 101 F25J 3/04 101

Claims (4)

[Claims] A gas turbine having a compressor, a mechanism for extracting a part of the compressor discharge air, a combustor for supplying and burning the compressor discharge air, nitrogen and fuel, and a turbine; An oxygen production facility for separating oxygen and nitrogen from air, and a gasifier that gasifies coal or heavy oil using the oxygen or the oxygen-enriched air obtained by mixing the oxygen and the air to generate a combustible gas, A heat exchanger for exchanging heat between the air extracted from the compressor of the gas turbine and the nitrogen that has been separated and pressurized in the oxygen production facility, and supplies the nitrogen after the heat exchange to the gas turbine combustor, In the gasification combined cycle power plant that supplies the generated combustible gas as the fuel to the gas turbine combustor, the amount of extracted air is controlled so that the thermal efficiency is maximized in accordance with the state of the gasification combined cycle power plant. Gasification combined cycle power plant, characterized in that it comprises location. A gas turbine having a compressor, a mechanism for extracting a part of the compressor discharge air, a combustor for supplying and burning the compressor discharge air, nitrogen, and fuel; and a turbine. An oxygen production facility for separating oxygen and nitrogen from air, and a gasifier that gasifies coal or heavy oil using the oxygen or the oxygen-enriched air obtained by mixing the oxygen and the air to generate a combustible gas, A gas exchanger for exchanging heat between the air extracted from the compressor of the gas turbine and the combustible gas generated by the gasifier, and supplying the combustible gas after heat exchange to the gas turbine combustor; An integrated gasification combined cycle power plant comprising a device for controlling the amount of bleed air to maximize thermal efficiency according to the state of the combined gasification combined cycle plant. 3. An apparatus for controlling the amount of bleed air so that the temperature of bleed air after heat exchange in the heat exchanger becomes a target value in the integrated gasification combined cycle power plant according to claim 1 or 2. A combined gasification combined cycle plant characterized by comprising: 4. An integrated gasification combined cycle plant according to claim 1 or 2, wherein the state of the combined gasification combined cycle plant is input, and the amount of extracted air at which the thermal efficiency is maximized is calculated by an analysis model. A combined gasification power plant comprising a device for controlling the bleed air flow rate according to the amount calculated by