JPH07279621A - Coal burning compound power generation facility - Google Patents

Abstract

PURPOSE:To employ a pertient heat source for drying coal, etc., in a compound power generation facility in which coal, etc., is crushed and gasified to generate power by the use of a gas turbine. CONSTITUTION:Coal 1 supplied to a gasification furnace 7 for gasifying coal is crushed and dried in a mill 2. For drying the coal 1 in the mill 2, a mill drying air 27 is supplied. The mill drying air is heated by a steam type air heater 25, and as its heat source, a high pressure bleed steam 37, an intermediate pressure bleed steam 38, and a low pressure bleed steam 39 carried from plural places in the steam system of a steam turbine 31 are switched to be introduced. Thus, the steam having the temperature which corresponds to the total moisture in coal can be used efficiently as a heat source. Further, some examples show that a bleed air 18 carried from a gas turbine air compressor 17 to the gasification furnace 7 can be used as the heat source.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a carbon-containing solid fuel such as coal (collectively referred to as coal in the present invention), which is pulverized into gas, which is combusted by a gas turbine to generate electric power. The present invention relates to a coal-fired combined cycle power generation facility that drives a steam turbine with steam generated in an exhaust heat recovery boiler of a turbine to generate electricity.

[0002]

2. Description of the Related Art In the above coal-fired combined cycle power generation facility, heated air is supplied to a mill (crusher) for crushing and drying coal to dry the coal. Conventionally, steam extracted from an intermediate stage of a steam turbine is used as a heat source for obtaining the heated air. FIG. 5 shows the configuration of such a conventional coal-fired combined cycle power generation facility.

First, the overall structure of the coal-fired combined cycle power generation facility shown in FIG. 5 will be described. Coal 1 is supplied to a mill (crusher) 2 and is crushed and dried while being in contact with mill drying air 27. It becomes pulverized coal 3. The pulverized coal 3 is sent to the pulverized coal supply device 4, quantified by the feeder 5, and supplied to the gasification furnace 7 by the supply pipe 6, and the gasifying agent flow control valve 2
It is gasified together with the gasifying agent supplied through the supply pipe 22 from 1. The heat generated during gasification is removed by the gasification furnace heat exchanger 8, and the generated steam is sent to the steam turbine 31.

The gas produced in the gasification furnace 7 passes through the produced gas pipe 9 and is passed through the gas purifying device 10 to dust and S (sulfur).
The gas is removed, and is quantified by the fuel control valve 12 and is sent to the combustor 13 through the purified gas pipe 11 and burned in the combustor 13, and the combustion gas is expanded in the gas turbine 14,
Generate electricity at 6. The combustion gas is sent to the exhaust gas boiler 28 via the exhaust gas duct 15.

Most of the air compressed by the air compressor 17 of the gas turbine 14 is used for combustion in the combustor 13, but part of it is extracted as extracted air 18 to the gasification furnace 7. The extracted air 18 is cooled to a predetermined temperature by an air cooler 19 and then pressure-increased by an air booster 20 and is supplied to the gasification furnace 7 as a gasifying agent through a gasifying agent flow rate control valve 21 and a supply pipe 22.

A main steam 30 which is a combination of the exhaust heat recovery boiler 28 and the steam generated in the gasifier heat exchanger 8 as described above.
Is sent to the steam turbine 31 and power is generated by the generator 32. Exhaust gas from the steam turbine 31 is condensed by a condenser 33 and is boosted by a pump 34.

Mill drying air 27 supplied to the mill 2.
Is obtained by heating the air pressurized by the mill dry air fan 23 with the steam air heater 25.
The steam-type air heater 25 uses the steam 24 extracted from the intermediate stage of the steam turbine 31 as a heat source, and the air heated by the steam-type air heater 25 passes through the flow rate adjusting damper 26 and the above-mentioned mill drying air 27. Is supplied to the mill 2 and used to crush and dry the coal 1.

[0008]

Although the proportion of water content (total water content) of coal varies depending on the brand, as shown in FIG. 4, the amount of heat required for drying and the amount of heat required for drying coal depend on the total water content. Required air temperature is different. That is, as can be seen from FIG. 4, in the case of coal having a total water content of 5%, the temperature of the air required for drying the coal is 125 ° C.
0% coal requires air at a temperature of 300 ° C.

Since the ordinary steam type air heater 25 used in the conventional apparatus utilizes latent heat of steam, the temperature of air that can be heated is the highest, but at a temperature equal to or lower than the saturation temperature at the pressure of steam as a heat source. is there. For example, high-pressure steam of 90ata or more is required to bring the air 27 for drying coal to 300 ° C, whereas steam having a pressure of about 4ata is needed to obtain air of 125 ° C.

Therefore, in the conventional equipment, if the steam extraction point is determined corresponding to coal having a high total moisture content, the plant efficiency will be impaired when another coal having a low total moisture content is used. Further, if the steam extraction point is determined corresponding to coal having a low total water content, there is a drawback that coal having a high total water content cannot be dried and cannot be operated.

Further, in the conventional equipment, since the steam 30 which should originally work in the steam turbine 31 is extracted as a heat source for obtaining the drying air in the mill 2, the power generation amount of the steam turbine 31 is reduced. However, there is a drawback that the plant efficiency is reduced accordingly.

The amount of heat required for drying in the mill 2 depends on the water content in the coal, but the total water content in the coal is 10 to 20%, but 1.2 to 2.5% of the heat input to the plant is required. Therefore, the improvement of the coal drying system will contribute to the improvement of plant efficiency.

The present invention eliminates the drawbacks found in the conventional coal-fired combined cycle power generation facility described above, and in order to dry the water contained in the coal to be used, steam of a pressure (temperature) commensurate with the water content is used. It is an object to provide a coal-fired combined cycle power generation facility that can be used and operate efficiently with a wide range of coal properties.

Furthermore, the present invention effectively utilizes a heat source that has not contributed to power generation in the conventional equipment as a heat source for the mill drying air, except for the drawbacks found in the conventional coal-fired combined cycle power generation equipment. It is an object of the present invention to provide a coal-fired combined cycle power generation facility that can reduce the amount of steam extracted from the steam turbine, increase the output of the steam turbine, and improve plant efficiency.

[0015]

According to the present invention, coal is pulverized and dried in a mill and supplied as a fine powder fuel to a gasification furnace for gasification with an oxygen-containing gas, and the generated CO, H ₂ -containing gas is gasified. In a coal-fired combined cycle power generation facility that supplies power to a turbine to generate power, introduces the exhaust gas of the gas turbine into an exhaust heat recovery boiler to generate steam, and guides the steam to the steam turbine together with the steam generated in the gasification furnace to generate power. In order to solve the problem of efficiently using steam with a pressure commensurate with the water content of the coal, the steam extracted from multiple points in the steam system of the steam turbine is switched as a heat source for drying the water contained in the coal in the mill. By adopting such a configuration, it is possible to select and guide.

As described above, by constructing the steam turbine so that steam in different states can be switched from a plurality of steam systems to be used, higher pressure steam is extracted from coal having a high total water content to obtain a total water content. It is possible to extract lower pressure steam for coal with a small amount. Therefore, it is possible to obtain an appropriate dry heat source for a wide range of coal properties and to improve plant efficiency.

According to another aspect of the present invention, as described above,
Coal is pulverized and dried in a mill, and it is supplied as fine powder fuel to a gasifier and gasified with an oxygen-containing gas. The generated CO and H ₂ -containing gas is supplied to a gas turbine to generate electricity, and exhaust gas from the gas turbine is discharged. In a coal-fired combined cycle power generation facility that introduces steam into a heat recovery boiler and guides it to a steam turbine together with the steam generated in the gasification furnace to generate power, heat generated in the facility that has not conventionally contributed to power generation. By effectively utilizing as a heat source for mill drying air, in order to solve the problem of increasing the plant efficiency by reducing the amount of steam extracted from the steam system of the steam turbine, as a heat source for drying coal in the mill described above. A configuration is adopted in which the extracted air guided from the air compressor driven by the gas turbine to the gasification furnace is used.

The extracted air from the gas turbine air compressor to the gasification furnace has a temperature of 350 to 400 ° C., but conventionally, this is cooled by the air cooler to the inlet temperature of the air booster (100 ° C. or less), The cooling endotherm here does not contribute to power generation. In the other aspect of the present invention having the above-described configuration, since this heat amount is used as a heat source for mill drying, the extraction amount from the steam system of the steam turbine as mill drying steam is reduced (0 during normal operation), and the output of the steam turbine is reduced. And the plant efficiency is improved.

[0019]

EXAMPLE A coal-fired combined cycle power generation system according to the present invention will be specifically described below with reference to the illustrated examples. In the following examples, the same components as those of the conventional coal-fired combined cycle power generation facility shown in FIG. 5 are designated by the same reference numerals, and duplicated description thereof will be omitted.

(First Embodiment) First, the first embodiment shown in FIG. 1 will be described. In the embodiment shown in FIG. 1, the difference from the configuration of the conventional coal-fired combined cycle power generation facility shown in FIG. 5 is the heating configuration of the mill drying air 27. That is,
In the configuration of FIG. 1, as a steam source for heating the steam type air heater 25, for example, a plurality of places such as high-pressure steam of A, medium-pressure steam of B, low-pressure steam of C are provided, and depending on the brand of coal (total moisture). It can be switched and used. The flow rate of the steam selected by these switching is controlled by the control valve 24 and introduced into the steam air heater 25. Other configurations are the same as those of the conventional equipment shown in FIG.

Therefore, in the equipment of this first embodiment, the steam having a pressure (temperature) corresponding to the total water content of the coal to be used is AC.
Since any one of them is guided to the air heater 25, the heat of the extracted steam is effectively used for a wide range of coal properties, and the plant efficiency can be improved.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 2, the difference from the configuration of the conventional coal-fired power generation facility shown in FIG. 5 is the heating configuration for the mill drying air 27.

That is, in the equipment of FIG. 2, extracted air 1 from the gas turbine air compressor 17 to the gasification furnace 7 is extracted.
8 is sent to the air heater 35, and the mill dry air fan 2
The air pressurized at 3 is heated to the temperature required for coal drying in the mill. The air heated in the air heater 35 is supplied to the mill 2 as mill drying air 27 after being quantified by the flow rate adjusting damper 26 through the steam type air preheater 25 (not required except at the time of start-up).

In this way, the gas turbine air compressor 1
The amount of extracted air from the steam system of the steam turbine can be reduced by effectively utilizing the heat held by the extracted air introduced from the 7 outlet to the gasification furnace 7 for mill drying, so that the steam turbine output increases. Other configurations of the equipment shown in FIG. 2 are the same as those of the conventional equipment shown in FIG. 5, and description thereof will be omitted.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 3, the extracted air 18 from the outlet of the gas turbine air compressor 17 to the gasification furnace 7 is cooled by the air-air heat exchanger 36 and then sent to the air heater 35 to be supplied to the mill 2 Heating dry air to. The extracted air 18 that has exited the air heater 35 is sent to the air cooler 19, is pressurized by the air booster 20, is heated by the air-air heat exchanger 36, and is sent to the gasification furnace 7.

In the present embodiment, the temperature for supplying the gasifying agent to the gasification furnace 7 can be kept high, which has the advantage of improving gasification efficiency, but the amount of heat exchanged in the air heater 35 decreases, so that
Since the amount of heat required for drying cannot be secured depending on the coal, in that case, the steam for mill drying 24 is introduced into the steam type air heater 25 to heat the shortage. The rest of the configuration of the third embodiment is the same as the equipment shown in FIG. 2, and the description thereof is omitted.

The present invention has been specifically described above based on the illustrated embodiments, but the present invention is not limited to these embodiments, and its specific constitution is within the scope of the present invention shown in the claims. It goes without saying that various changes may be added to the. For example, in the above embodiment, air is introduced as the gasifying agent into the gasification furnace, but it may be a gasification furnace in which oxygen or oxygen-enriched air is introduced instead of air. In that case, an air separator and an oxygen compressor are installed downstream of the air cooler 19.

[0028]

As described above in detail, in the coal-fired combined cycle power generation facility of the present invention, as a heat source for heating the drying air in the mill, the steam system of the steam turbine is used depending on the total water content of the coal. By switching the extraction points to introduce steam of desired pressure and temperature, it is possible to operate with high plant efficiency against a wide range of changes in coal properties.

Further, in the coal-fired combined cycle power generation facility of the present invention, as the heat source for drying coal in the mill, not the extracted steam from the steam system of the steam turbine but the extracted gas from the gas turbine air compressor outlet to the gasification furnace. With a configuration that utilizes the heat that the air has (the amount of heat that was originally discarded to the cooling water system), the amount of extracted steam from the steam system of the steam turbine decreases (0 in normal operation), so The output is increased and the plant efficiency is increased.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of a coal-fired combined cycle power generation facility according to a first embodiment of the present invention.

FIG. 2 is a system diagram showing a configuration of a coal-fired combined cycle power generation facility according to a second embodiment of the present invention.

FIG. 3 is a system diagram showing a configuration of a coal-fired combined cycle power generation facility according to a third embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the total water content of coal and the air temperature required for its drying.

FIG. 5 is a system diagram showing a configuration of a conventional coal-fired combined cycle power generation facility.

[Explanation of symbols]

 1 Coal 2 Mill (Grinding Machine) 7 Gasifier 8 Gasifier Heat Exchanger 10 Gas Purifier 13 Combustor 14 Gas Turbine 17 Gas Turbine Air Compressor 18 Extraction Air to Gasifier 23 Mill Dry Air Fan 24 Mill Dry Steam 25 Steam-type air heater 27 Mill drying air 28 Exhaust heat recovery boiler 30 Main steam 31 Steam turbine 35 Air heater 36 Air-air heat exchanger 37 High pressure extraction steam 38 Medium pressure extraction steam 39 Low pressure extraction steam

Claims (2)

[Claims] 1. Coal is pulverized and dried by a mill, and is supplied as fine powder fuel to a gasification furnace to be gasified with an oxygen-containing gas, and the generated CO and H ₂ containing gas is supplied to a gas turbine to generate electricity. In the coal-fired combined cycle power generation facility, which introduces the exhaust gas of the turbine into the exhaust heat recovery boiler to generate steam, and guides to the steam turbine together with the steam generated in the gasification furnace to generate power, the water content in the coal in the mill A coal-fired combined cycle power generation facility having a configuration in which steam extracted from a plurality of locations in the steam system of the steam turbine is selected and guided as a heat source for drying the steam. 2. Coal is pulverized and dried by a mill and is supplied as fine powder fuel to a gasification furnace to be gasified with an oxygen-containing gas, and the generated CO and H ₂ containing gas is supplied to a gas turbine to generate electricity. In the coal-fired combined cycle power generation facility, which introduces the exhaust gas of the turbine into the exhaust heat recovery boiler to generate steam, and guides to the steam turbine together with the steam generated in the gasification furnace to generate power, the water content in the coal in the mill A combined coal-fired combined cycle power generation facility having a configuration in which extracted air introduced from an air compressor driven by the gas turbine to the gasification furnace is used as a heat source for drying.