UA64812C2 - Method for operation of steam-gas electric power plant on combined fuel (solid with gaseous or liquid) and steam-gas unit for its implementation - Google Patents

Abstract

A steam-gas unit has a steam circuit, this comprises a steam generator with an intermediate steam overheater, a steam turbine, a system of regeneration water heaters and feeding pump, and a gas-steam circuit, this comprises a gas-steam turbine engine, it includes installed in sequence compressor, combustion chamber and turbine connected by the shaft to mechanical energy transformer to electric energy; and placed in sequence in direction of motion of worked-out gases boiler-utilizer, heat exchanger for preliminary heating of condensate and condenser. The unit is equipped with the node for steam collecting, this is with its inlet connected at the same time to the steam outlet of the boiler-utilizer and intermediate steam overheater of the steam generator, and with the outlet - to the combustion chamber of gas-turbine engine; and the heat exchanger of condensate preliminary heating is with its water inlet connected through deaerating unit to the outlet of the condenser, and with its outlet - to the feeding pump of steam generator.

Description

The invention relates to the field of steam-gas turbine construction, in particular to steam-gas power plants.

As an analogue, the method of operation of a steam-gas power plant on combined organic fuel (solid or gaseous or liquid) is adopted, which includes the processes of compressing air, burning gaseous or liquid fuel in it, converting the potential energy of the obtained combustion products into mechanical work during their expansion, burning in their flow of solid fuel and generation of steam, transformation of its potential energy into mechanical work during expansion with intermediate overheating, condensation of water vapor and mixing of combustion products with atmospheric air (see Rzhkin V.Ya. Teplovye zlektricheskie stancii. - M.: Znergia, 1976- 447 p.)

The known method has a disadvantage, which is that the temperature (thermal potential) of the generated steam is low (about 600°C). As a result, the share of thermal energy of the steam converted into work is insignificant.

As a prototype, the method of operation of the combined power plant was adopted, which includes air compression in the compressor with subsequent supply with fuel to the combustion chamber of the gas turbine and to the combustion chamber of the steam-gas turbine with a secondary zone, expansion of the fuel combustion products in the turbines, followed by cooling in the recovery boilers , additional cooling of the combustion products of the steam-gas turbine with condensation of water vapor, the supply of condensate to waste boilers with its subsequent heating, evaporation and separation of steam in separators and superheating of steam, and mixing of superheated steam with air supplied to the combustion chamber of the steam-gas turbine, and part the water from the separators is introduced in the heat exchanger into contact with the compressed air taken after the compressor with partial evaporation and cooling of the water and heating of the steam-air mixture, while the latter is additionally heated by the heat of the combustion products before cooling them in the recovery boilers and feeding them into the combustion chamber gas turbine, and cooled water is mixed with condensate (see 5!) 1830421 A1, cl. EO1K21/04, 30.07.93 Bull. 28).

As a prototype, a steam-gas installation was adopted, which includes a compressor, a combustion chamber with a gas turbine and a combustion chamber with a steam-gas turbine, which is connected by a shaft to the consumer of work and sequentially located after the turbines in the direction of movement of spent gases are boilers-utilizers, which with their entrances water are connected to the condenser, which is connected to the steam-gas turbine outlet of the steam-gas turbine utilization boiler. A steam-air mixture heater is installed between the steam-gas turbine and its recovery boiler, which is connected to a heat exchanger, in which a steam-air mixture is obtained from the hot water taken from the separator drums of the recovery boilers in the air stream taken from the compressor.

The combustion chamber of the steam-gas turbine is connected by pipelines to the heater of the steam-air mixture and by steam to the recovery boilers (see 50 1830421 A1, cl. EO1K21/04, 30.07.93 Bull.28).

The known method has a drawback, which is that it cannot use stone and brown coal as fuel.

The invention solves the problem of creating a method of operation of a steam-gas power plant on combined fuel (solid with gaseous or liquid).

The task is solved by the fact that in the method of operation of a steam-gas power plant on combined fuel, which includes the processes of burning fuel with the formation of superheated steam, partial expansion of superheated steam with the transformation of its potential energy into kinetic energy, and kinetic energy into mechanical energy with simultaneous transformation into electrical energy, followed by supply of steam after expansion to intermediate superheat in the steam circuit, and including the processes of air compression, combustion of fuel in it in the combustion chamber, mixing of the obtained combustion products with water vapor in the combustion chamber, expansion of the gas-vapor mixture and utilization of the heat of the spent gases in the boiler-utilizer in in the gas-steam circuit, according to the invention, gaseous or liquid fuel is burned in the combustion chamber, heat utilization of the spent gases after the boiler-utilizer is carried out with the production of condensate and compression of the spent gases, while water vapor, which is fed into the combustion chamber, is obtained by by a single union of the steam of the gas-steam circuit, formed as a result of heating the condensate in the recovery boiler and the steam of the steam circuit after intermediate overheating, obtained from the condensate of the gas-steam circuit preheated by the heat of the spent gases, as a result of burning solid fuel, while the expansion of the gas-steam mixture carries out transformation its potential energy into kinetic energy, and kinetic energy into mechanical energy with the simultaneous transformation of the latter into electrical energy, while the steam of the steam circuit before intermediate overheating is expanded to a pressure that exceeds the pressure in the combustion chamber by 3-4 bars.

The task is solved by the fact that a steam-gas installation (power plant) containing a steam circuit consisting of a connected steam generator, a steam turbine connected by a shaft to a converter of mechanical energy into electrical energy, and an intermediate superheater of steam, a system of regenerative heaters, a feed pump and a gas-steam circuit consisting of a gas-steam turbine engine, which includes a sequentially arranged compressor, a combustion chamber with a steam supply and a turbine, and is sequentially located in the direction of movement of spent gases, a boiler-utilizer, according to the invention, the gas-steam circuit is additionally equipped with sequentially located in the direction of movement of spent gases gases after the boiler-utilizer by a heat exchanger for pre-heating the condensate, a condenser and a compression compressor connected at its outlet to the atmosphere and connected by a shaft to a gas-steam turbine engine, which is connected by a shaft to a converter of mechanical energy into an electric or steam turbine, the condenser by its the water outlet through the deaerator is connected to the utilization boiler inlet and at the same time its outlet and water inlet is connected, respectively, to the inlet and outlet of the condensate cooling unit, and the steam-gas plant is additionally equipped with a steam collection unit, which is connected to the steam outlets of the boiler through its inlets at the same time - the heat exchanger and the intermediate steam heater of the steam generator and its output - to the combustion chamber of the gas-steam turbine engine, and the heat exchanger for preheating the condensate is connected with its water input through the deaerator to the condenser output, and its output - through the feed pump and the system of regenerative heaters to the steam generator.

The new set of essential features is absent in known technical solutions and allows you to obtain the following advantages:

significantly increases the temperature potential of the steam obtained due to the thermal energy of solid fuel and thereby significantly (almost 2 times) increases its work, which significantly increases the thermodynamic efficiency of the power plant; provides a significant (approximately twofold) reduction of harmful emissions into the environment; significantly reduces the dimensions, mass and cost per kilowatt of the installed capacity of the power plant.

All the listed advantages are aimed at increasing production efficiency and reducing the cost of electricity.

The figure shows the thermal scheme of a steam-gas plant that implements the proposed method.

The steam-gas installation consists of two circuits of steam and gas-steam. The steam circuit includes a steam generator 1, a steam turbine 2, which is connected by a shaft to a converter 3 of mechanical energy into electrical energy (electric generator), an intermediate steam superheater 4, a system of regenerative water heaters 5 and a feed pump 6.

The gas-steam circuit includes a gas-steam turbine engine 7 with a compressor 8, a combustion chamber 9 and a turbine 10 located in series, and located in series in the direction of movement of the spent gases, a boiler-utilizer 11, a heat exchanger for preheating the condensate 12, a condenser 13 and a compression compressor 14, which is connected at its outlet with the atmosphere and connected to the gas-steam turbine engine 7 or steam turbine 2. The gas-steam turbine engine 7 is connected by a shaft to the converter 15 of mechanical energy into electrical energy. Condenser 13 is connected to the water outlet through the deaerator (not shown in the drawing) to the inlet of the boiler-utilizer 11 and at the same time its outlet and water inlet is connected to the inlet and outlet of the condensate cooling unit 16. The steam-gas plant is additionally equipped with a steam collection unit 17, which is connected by its inputs to the steam outputs of the recovery boiler 11 and the intermediate steam superheater 4 of the steam generator 1, and the condensate preheating heat exchanger 12 is connected by its water inlet through the deaerator to the condenser inlet 13, and its exit - through the feed pumpb and into the system of regenerative heaters 5 to the steam generator 1.

The method is carried out by a steam-gas plant as follows. Preheated in the heat exchanger 12 and the system of regenerative heaters 5, the condensate is fed by the feed pump 6 to the steam generator 1, where it is evaporated, and the resulting steam is superheated and sent to the steam turbine 2, where it is partially expanded to a pressure that exceeds the pressure in the combustion chamber 9 of the gas turbine engine 7 by 3-4 bar, thus converting part of the potential energy of the steam into kinetic energy, and kinetic energy into mechanical energy, which will be simultaneously converted into electrical energy in the electric generator Z. After the turbine 2, the steam is sent to the superheater 4 of the steam generator 1 for intermediate overheating due to the heat of the solid fuel. At the same time, air through the compressor 8 of the gas turbine engine 7 is fed into the combustion chamber 9, where gaseous or liquid fuel is directed and burned. The resulting combustion products are mixed in the combustion chamber 9 with water vapor supplied from the steam collection unit 17. Moreover, part of the steam is supplied to the primary zone of the combustion chamber (combustion zone) to suppress nitrogen oxides and therefore it is called ecological steam. The steam-gas mixture obtained in the combustion chamber 9 is sent to the turbine 10, where it is expanded, while converting its potential energy into kinetic energy, which will then be converted into mechanical energy, and the obtained mechanical energy will simultaneously be converted into electrical energy in the electric generator 15. The steam-gas mixture spent in the turbine 10 ( spent gases) are sent to the recovery boiler 11, where their heat is utilized to form steam, which is fed to the steam collection unit 17 and mixed there with the steam fed there from the intermediate superheater 4 of the steam generator 1, from where the resulting steam mixture is sent to the combustion chamber 9 The waste gases cooled in the boiler-utilizer 11 are sent to the condensate preheating heat exchanger 12, where their heat is further utilized with the transfer of its condensate, which is sent to the steam generator 1 through the feed pump b and the system of regenerative heaters 5. After the heat exchanger 12, the cooled waste gases are fed into the condenser 13, where they are cooled and condensed and water vapor in contact with the condensate cooled in the condensate cooling unit 16. The condensate supplied and received in the condenser 13 is divided into two streams: one is sent through the deaerator simultaneously to the inlets of the boiler-utilizer 11 and the heat exchanger 12 for preheating the condensate, and the second - to the condensate cooling unit 16, and the cooled and dried exhaust gases are sent to the compression compressor 14 , where they are pressed to atmospheric pressure and discharged into the environment.

In comparison with the prototype, the proposed method of operation of the steam-gas plant ensures the operation of the power plant on combined (solid, gaseous or liquid) fuel. In comparison with the analogue, the proposed method of operation of a steam-gas power plant on combined organic fuel allows to significantly increase its efficiency, i.e. thermodynamic efficiency. This is due to the fact that the share of the heat converted into work supplied to the working body clearly depends on its temperature.

I-F(1-To/TIt), where: I - work (part of the heat is converted into work);

O - heat supplied to the working body;

To, Tt - absolute temperatures, respectively, of the environment and the working fluid at the turbine inlet.

From the dependence, it can be seen that at a constant temperature To of the environment, the more heat is converted into work, the higher the temperature T of the working fluid at the entrance to the turbine. In the considered analog and other known analogs, Tt does not exceed 873 K, and the prospects for its increase are not yet foreseen Therefore, the theoretical amount of heat converted into work does not exceed 6795. In the same proposed method, using modern Ti-1523 K steam-gas plants, which increases the share of heat converted into work to 8195. Taking into account the further new increase in TU, the share of heat converted into work will increase even more.

In addition, at the same time, the specific power of the power plant will increase sharply by approximately 1.7-2 times, which significantly reduces capital costs, and therefore reduces the cost of a kilowatt of installed capacity. This is confirmed by the relationship shown below, from which it follows that the power of the steam-gas plant increases in proportion to the increase in the temperature of the working fluid at the turbine inlet.

Ma sSet - Pp t where: a - consumption of the working fluid;

Si - isobaric heat capacity of the working fluid;

Tt - gas temperature at the turbine inlet;

P. - degree of expansion of the working body in the turbine; n - adiabatic turbine efficiency;

Mu is the power on the turbine shaft.

At the same time, emissions of harmful substances into the atmosphere are reduced by more than 2 times per unit of work performed.

The table shows the comparative data of the gas turbine with the emission of spent gases from the gas turbine, into the furnace of the steam generator (analog) and the proposed steam and gas plant.

Table

Name of PGU PGU-400 Proposed PGU

Type of steam turbine app. Steam generator and high pressure cylinder

K-300-240 turbines K-300-240

Power of the steam turbine, MW 111.3

Parameters of steam at the turbine inlet flow rate, kg/h 800 800 temperature, "С

The capacity of the gas station in MW

Efficiency of PSU

It follows from the given data that the proposed method of operation of the steam-gas power plant not only ensures operation on combined fuel, but at the same time significantly increases its thermodynamic efficiency (increase in efficiency) and at the same time significantly increases the specific power, which significantly reduces the cost of a kilowatt of the installed capacity of the power plant.

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M vo g is TD Thu

Z Z x 1 mm I mEZ m ana kh i

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Claims (2)

1. The method of operation of a steam-gas power plant on combined fuel, which includes the processes of fuel combustion with the formation of superheated steam, partial expansion of superheated steam with the conversion of its potential energy into kinetic energy, and kinetic energy into mechanical energy with simultaneous conversion into electrical energy with subsequent steam supply after expansion to intermediate overheating in the steam circuit, and also includes the processes of air compression, burning of fuel in it in the combustion chamber, mixing of the obtained combustion products with water vapor in the combustion chamber, expansion of the gas-vapor mixture, and utilization of the heat of waste gases in the boiler-utilizer in the gas-steam circuit, which differs in that gaseous or liquid fuel is burned in the combustion chamber, heat utilization of waste gases after the boiler-utilizer is carried out with the production of condensate and compression of waste gases, and the water vapor fed into the combustion chamber is obtained by preliminary combining of gas of the air circuit, formed as a result of heating the condensate in the recovery boiler, and the steam of the steam circuit after intermediate overheating, obtained from the heat of the condensate of the gas-steam circuit pre-heated by the waste gases as a result of the combustion of solid fuel, at the same time, during the expansion of the gas-steam mixture, its potential energy is converted into kinetic energy , and kinetic energy into mechanical energy with simultaneous transformation of the latter into electrical energy. 2. The method of operation of a steam-gas power plant according to claim 1, which differs in that the steam of the steam circuit before intermediate overheating is expanded to a pressure that exceeds the pressure in the combustion chamber by 3-4 bars. C. A steam-gas plant (power plant) that contains a steam circuit consisting of a connected steam generator, a steam turbine connected by a shaft to a mechanical energy into electrical energy converter, and an intermediate steam superheater, a system of regenerative heaters, a feed pump and a gas-steam circuit, which consists of a gas-steam turbine engine, which includes a compressor, a combustion chamber with steam supply and a turbine located in series, and a recovery boiler located in series in the direction of movement of exhaust gases, which is characterized by the fact that the gas-steam circuit is additionally equipped with sequentially located in the direction of movement of exhaust gases after the boiler - of the heat exchanger with a heat exchanger for preheating the condensate, a condenser and a pressurization compressor connected by its outlet to the atmosphere and a shaft with a gas-steam turbine engine, which is connected by a shaft to a converter of mechanical energy into an electric or steam turbine, a condenser with its outlet through water through a deaerator, connected is connected to the inlet of the waste water boiler and at the same time its outlet and water inlet is connected to the inlet and outlet of the condensate cooling unit, and the steam-gas plant is additionally equipped with a steam collection unit, which is connected with its inputs to the steam outlets of the waste water boiler and the intermediate steam superheater of the steam generator and its outlet - to the combustion chamber of the gas-steam turbine engine, and the condensate preheating heat exchanger is connected with its inlet via water through the deaerator to the outlet of the condenser, and its outlet - through the feed pump and system of regenerative heaters - to the steam generator.