Oxygen-fuel power plant for combined production of electricity and heat

Abstract

FIELD: electric power engineering.SUBSTANCE: invention can be used in the development of environmentally friendly power plants with oxygen-fuel power plants. An oxygen-fuel power plant comprises a series-connected compressor, a combustion chamber with a connected fuel compressor, and a gas turbine, the shaft of which is connected to an electric generator. The outlet of the gas turbine is connected through a waste heat boiler comprising gas-water and gas-air heat exchangers to a cooler-separator and a multi-stage compressor. The steam turbine circuit includes a high-pressure steam turbine and a low-pressure steam turbine connected to a common electric generator, a deaerator, a steam condenser, a condensate pump, a feed pump, as well as first and second network heaters connected through first and second mixing points to a heat consumer and a network pump. The power plant is equipped with an air separation unit, the first output of which is connected to the combustion chamber, and the second output is connected to the second input of the second network heater via the first air circuit, wherein the second output of the second network heater is connected to the input of the air separation unit via the second air circuit.EFFECT: reducing heat losses in an air separation plant and increasing the efficiency of fuel heat utilization in an oxygen-fuel power plant.1 cl, 2 dwg

Description

[0001] Field of technology to which the invention relates

[0002] The invention relates to the field of electric power engineering and can be used in the development of power plants with low emissions of harmful substances into the atmosphere.

[0003] Technology Level

[0004] An oxygen-fuel power plant is known that operates on a semi-closed cycle with oxygen combustion of fuel (Bolland O., Saether S. New concepts for natural gas fired power plants which simplify the recovery of carbon dioxide / / Energy Conversion and Management. - 1992. - Vol. 33. - No. 5-8. - Pp. 467-475.), containing a multi-stage compressor, a combustion chamber, a fuel compressor, an air separation unit, a gas turbine, a waste heat boiler, a cooler-separator, a multi-stage compressor with intermediate cooling, a steam turbine, a condenser, a pump, and a first and second electric generator.

[0005] The disadvantages of this technical solution are large heat losses in the condenser of the steam turbine unit, large heat losses at the outlet of the waste heat boiler and large heat losses in the air separation unit.

[0006] The closest in technical essence to the proposed invention is an oxygen-fuel power plant operating on a semi-closed cycle with oxygen combustion of fuel (Zelaschi A. et al. Semi-Closed Oxy-Combustion Combined Cycles (SCOC-CC) for Combined Heat and Power Applications / / Turbo Expo: Power for Land, Sea, and Air. - American Society of Mechanical Engineers, 2024. - Vol. 87974. - P. V005T06A043.), comprising a compressor, a fuel compressor, an air separation unit connected to a combustion chamber, which is connected in series with a gas turbine, a waste heat boiler containing a steam-water and water path, a cooler-separator. The cooler-separator is connected in parallel with a multi-stage compressor with intermediate cooling and a compressor. The steam-water path of the waste heat boiler is connected in series with a steam turbine, a steam condenser, a condensation pump, a deaerator and a feed pump.The water circuit of the waste heat boiler is connected in series with the network heater, the heat consumer and the network pump.

[0007] The disadvantages of this technical solution are large heat losses in the air separation unit.

[0008] Disclosure of the essence of the invention

[0009] The technical problem solved by the proposed invention is to reduce heat losses in an air separation unit.

[0010] The technical result consists in increasing the heat utilization coefficient of the fuel of an oxygen-fuel power plant.

[0011] This is achieved in that the known oxygen-fuel power plant, containing a compressor, the output of which is connected to the first input of the combustion chamber, to the second input of which a fuel compressor is connected, to the third input of which the first output of the air separation unit is connected, the output of the combustion chamber is connected to a gas turbine, wherein the compressor of the gas turbine and the gas turbine are located on the same shaft and are mechanically connected to the electric generator of the gas turbine, the output of the gas turbine is connected in series with a waste heat boiler, which contains a series-connected gas-water two-flow heat exchanger containing a first hot gas circuit of the coolant and a cold steam circuit of the coolant, and a gas-air two-flow heat exchanger containing a second hot gas circuit of the coolant and a cold water circuit of the coolant, a cooler-separator and a multi-stage compressor with intermediate cooling,the outlet of the cold steam circuit of the coolant of the gas-water two-flow heat exchanger is connected to a high-pressure steam turbine, the outlet of the high-pressure steam turbine is connected to a low-pressure steam turbine, the high-pressure steam turbine and the low-pressure steam turbine are located on a common shaft and are mechanically connected to an electric generator, the first outlet of the low-pressure steam turbine is connected to the first inlet of the first network heater, the second outlet of the low-pressure steam turbine is connected to the first inlet of the deaerator, the third outlet of the low-pressure steam turbine is connected to the inlet of the steam condenser, the outlet of which is connected to the inlet of the condensate pump, the outlet of which is connected to the second inlet of the deaerator, the third inlet of the deaerator is connected via a condensate circuit to the first outlet of the first network heater, the outlet of the deaerator is connected to the inlet of the feed pump,the output of which is connected to the input of the cold steam circuit of the coolant of the gas-water two-flow heat exchanger of the waste heat boiler, the output of the cold water circuit of the coolant of the gas-air two-flow heat exchanger is connected to the first input of the first mixing point, the second output of the first network heater is connected to the second input of the first mixing point, the first output of the second network heater is connected to the third input of the first mixing point, the output of the first mixing point is connected to the heat consumer, the output of which is connected to the network pump, the output of the network pump is connected to the second mixing point, the first output of the second mixing point is connected to the cold water circuit of the coolant of the gas-air two-flow heat exchanger, the second output of the second mixing point is connected to the second input of the first network heater, the third output of the second mixing point is connected to the first input of the second network heater,the first outlet of the cooler-separator is connected to a multi-stage compressor with intermediate cooling, the second outlet of the cooler-separator is connected to the compressor, provided with first and second air circuits, wherein the second outlet of the air separation unit is connected to the second inlet of the second network heater by the first air circuit, the second outlet of the second network heater is connected to the inlet of the air separation unit by the second air circuit.,

[0012] Brief description of drawings

[0013] The essence of the invention is explained by the drawings, where Fig. 1 shows the basic thermal diagram of the proposed oxygen-fuel power plant for the combined production of electricity and heat, Fig. 2 shows the results of mathematical modeling of the thermal diagram of the proposed oxygen-fuel power plant in comparison with the prototype.

[0014] Implementation of the invention

[0015] The oxygen-fuel power plant for the combined production of electricity and heat comprises a compressor 1, a combustion chamber 2, a fuel compressor 3, an air separation unit 4, a gas turbine 5, a gas turbine electric generator 6, a waste heat boiler 7, a gas-water double-flow heat exchanger 8, a first hot gas circuit of the coolant 9, a cold steam circuit of the coolant 10, a gas-air double-flow heat exchanger 11, a second hot gas circuit of the coolant 12, a cold water circuit of the coolant 13, a cooler-separator 14, a multi-stage compressor with intermediate cooling 15, a high-pressure steam turbine 16, a low-pressure steam turbine 17, a steam turbine electric generator 18, a steam condenser 19, a condensing pump 20, a deaerator 21, a feed pump 22, network pump 23, first network heater 24, second network heater 25, first air circuit 26, second air circuit 27, first mixing point 28,heat consumer 29, second mixing point 30, condensate circuit 31.,

[0016] The outlet of compressor 1 is connected to the first inlet of combustion chamber 2, to the second inlet of which fuel compressor 3 is connected, to the third inlet of which the first outlet of air separation unit 4 is connected. The outlet of combustion chamber 2 is connected to gas turbine 5. Compressor 1 of gas turbine 5 and gas turbine 5 are located on the same shaft and are mechanically connected to electric generator of gas turbine 6.

[0017] The outlet of the gas turbine 5 is connected in series with the waste heat boiler 7, which contains a series-connected gas-water two-flow heat exchanger 8, containing a first hot gas circuit of the coolant 9 and a cold steam circuit of the coolant 10, and a gas-air two-flow heat exchanger 11, containing a second hot gas circuit of the coolant 12 and a cold water circuit of the coolant 13, a cooler-separator 14 and a multi-stage compressor with intermediate cooling 15. The outlet of the cold steam circuit of the coolant 10 of the gas-water two-flow heat exchanger 8 is connected to the high-pressure steam turbine 16.

[0018] The outlet of the high-pressure steam turbine 16 is connected to the low-pressure steam turbine 17. The high-pressure steam turbine 16 and the low-pressure steam turbine 17 are located on a common shaft and are mechanically connected to the electric generator 18.

[0019] The first outlet of the low-pressure steam turbine 17 is connected to the first inlet of the first network heater 24, the second outlet of the low-pressure steam turbine 17 is connected to the first inlet of the deaerator 21, the third outlet of the low-pressure steam turbine 17 is connected to the inlet of the steam condenser 19, the outlet of which is connected to the inlet of the condensate pump 20, the outlet of which is connected to the second inlet of the deaerator 21. The third inlet of the deaerator 21 is connected via the condensate circuit 31 to the first outlet of the first network heater 24.

[0020] The outlet of the deaerator 21 is connected to the inlet of the feed pump 22, the outlet of which is connected to the inlet of the cold steam circuit of the coolant 10 of the gas-water two-flow heat exchanger 8 of the waste heat boiler 7.

[0021] The outlet of the cold water circuit of the coolant 13 of the gas-air two-flow heat exchanger 11 is connected to the first inlet of the first mixing point 28, the second outlet of the first network heater 24 is connected to the second inlet of the first mixing point 28, the first outlet of the second network heater 25 is connected to the third inlet of the first mixing point 28. The outlet of the first mixing point 28 is connected to the heat consumer 29, the outlet of which is connected to the network pump 23. The outlet of the network pump 23 is connected to the second mixing point 30.

[0022] The first output of the second mixing point 30 is connected to the cold water circuit of the coolant 13 of the gas-air two-flow heat exchanger 11, the second output of the second mixing point 30 is connected to the second input of the first network heater 24, the third output of the second mixing point 30 is connected to the first input of the second network heater 25.

[0023] The second output of the air separation unit 4 is connected to the second input of the second network heater 25 by the first air circuit 26, the second output of the second network heater 25 is connected to the input of the air separation unit 4 by the second air circuit 27.

[0024] The first outlet of the cooler-separator 14 is connected to the multi-stage compressor with intermediate cooling 15, the second outlet of the cooler-separator 14 is connected to the compressor 1.

[0025] The oxy-fuel power plant for combined heat and power generation operates as follows.

[0026] A stream of carbon dioxide is fed from the cooler-separator 14 to the inlet of the compressor 1, which, after compression in the compressor 1, is directed to the first inlet of the combustion chamber 2, to the second inlet of which natural gas, pre-compressed in the fuel compressor 3, is fed, and oxygen obtained in the air separation unit 4 is fed to the third inlet of the combustion chamber 2. The gases formed during the fuel combustion process in the combustion chamber 2 are directed to the gas turbine 5. During the expansion process, the exhaust gases perform work in the gas turbine 5. Since the gas turbine 5, compressor 1 and the electric generator of the gas turbine 6 are located on the same shaft and are mechanically connected, the work performed by the gases during the expansion process in the gas turbine 5 is used to perform work in the process of air compression in the compressor 1 and to generate electric power at the terminals of the electric generator of the gas turbine 6.

[0027] After the hot mixture has been burned and useful work has been generated in the gas turbine 5, the exhaust gases pass through the hot gas circuit of the coolant 9 of the gas-water two-flow heat exchanger 8 of the waste heat boiler 7, where they transfer their heat to the working medium of the cold water circuit of the coolant 10 of the gas-water two-flow heat exchanger 8 of the waste heat boiler 7, after which they enter the input of the hot gas circuit of the coolant 12 of the gas-air two-flow heat exchanger 11 of the waste heat boiler 7, in which the process of transferring heat to the cold carbon dioxide circuit of the coolant 13 of the gas-air two-flow heat exchanger 11 of the waste heat boiler 7 takes place. Then the exhaust gases enter the cooler-separator 14, in which condensation of water vapor occurs and the removal of the resulting condensate from the cycle.Through the first outlet of the cooler-separator 14, excess carbon dioxide generated by natural gas combustion is directed to a multi-stage compressor with intermediate cooling 15, where the carbon dioxide is compressed and sent for disposal. The remaining working fluid is returned to the inlet of compressor 1 through the second outlet of the cooler-separator 14.

[0028] The superheated steam generated in the cold water circuit of the coolant 10 of the gas-water double-flow heat exchanger 8 of the waste heat boiler 7 is sent to the head of the high-pressure steam turbine 16. The steam exhausted in the high-pressure steam turbine 16 is sent to the low-pressure steam turbine 17. In the low-pressure steam turbine 17, part of the steam at outlet 1 is sent to heat the network water in the first network heater 24, from the second outlet it is sent to heat the main condensate in the deaerator 21, and the remaining steam is expanded to a pressure of 4.5 kPa, after which it is sent through the third outlet to the steam condenser 19. Due to the fact that the high-pressure steam turbine 16 and the low-pressure steam turbine 17 are connected by one shaft and are mechanically connected to the electric generator of the steam turbine 18, electrical energy is generated in it.

[0029] In the condenser of the steam turbine 19, the steam exhausted in the low-pressure steam turbine 17 is condensed, after which the condensate is sent to the condensate pump 20, which creates the necessary pressure for the condensate to pass through the deaerator 21. In the deaerator 21, the process of water deaerating takes place due to the steam extracted from the low-pressure steam turbine 17. The feedwater after the deaerator 21 is sent to the inlet of the feed pump 22, after which it is sent to the inlet of the cold steam circuit of the coolant 10 of the gas-water double-flow heat exchanger 8 of the waste heat boiler 7.

[0030] The cooled exhaust gases after the hot gas circuit of the coolant 9 of the gas-water double-flow heat exchanger 8 of the waste heat boiler 7 are sent to the hot gas circuit of the coolant 12 of the gas-air double-flow heat exchanger 11 of the waste heat boiler 7, where the network water is heated in the cold water circuit of the coolant 13 of the gas-air double-flow heat exchanger 11 of the waste heat boiler 7. The network water heated in the cold water circuit of the coolant 13 of the gas-air double-flow heat exchanger 11 of the waste heat boiler 7 is sent to the second inlet of the mixing point 28, where it is mixed with the network water heated in the first network heater 24, which is sent to the first inlet of the mixing point 28, and with the network water heated in the second network heater 25, which is directed to the third input of mixing point 28.After mixing point 28, the heated network water is directed to heat consumer 29, where it is cooled to a temperature of 70°C, after which it is directed by network pump 23 to the second mixing point 30. Through the first outlet of mixing point 30, the network water is directed to the first network heater 24, through the second outlet of mixing point 30, the network water is directed to the cold water circuit of the coolant 13 of the gas-air two-flow heat exchanger 11 of the waste heat boiler 7, through the third outlet of mixing point 30, the network water is directed to the second network heater 25.

[0031] The network water of the first network heater 24 is heated by steam taken from the first outlet of the low-pressure steam turbine 17, which, after condensation along the condensate circuit 31, is sent to the deaerator 21.

[0032] Air from air separation unit 4 is directed through first air circuit 26 to second network heater 25, where heat is transferred from the air to the network water. The cooled air flow from second network heater 25 is directed through second air circuit 27 to air separation unit 4.

[0033] Based on the results of mathematical modeling of the thermal circuit of the proposed oxygen-fuel power plant (Fig. 2), it was found that the fuel heat utilization coefficient increased by 6.3% compared to the prototype with the same thermodynamic parameters of the cycle: initial cycle temperature of 1060°C, initial pressure of 38.5 bar, pressure at the gas turbine exhaust of 1 bar, temperature at the inlet to the cooler-separator of 80°C.

[0034] The addition of the first 26 and second 27 air circuits to the invention circuit provides an additional supply of heat from the air separation unit 4 to the second network heater 25, which helps to reduce the heat power losses of the air separation unit 4 by 7 MW, thereby achieving an increase in the fuel heat utilization coefficient by 6.3%.

[0035] The use of the invention makes it possible to increase the heat utilization coefficient of the fuel of an oxygen-fuel power plant.

Claims

An oxygen-fuel power plant for the combined production of electricity and heat, comprising a compressor, the outlet of which is connected to the first inlet of a combustion chamber, to the second inlet of which a fuel compressor is connected, to the third inlet of which the first outlet of an air separation unit is connected, the outlet of the combustion chamber is connected to a gas turbine, wherein the compressor of the gas turbine and the gas turbine are located on the same shaft and are mechanically connected to the electric generator of the gas turbine, the outlet of the gas turbine is connected in series to a waste heat boiler, which contains a series-connected gas-water two-flow heat exchanger containing a first hot gas circuit of the coolant and a cold steam circuit of the coolant, and a gas-air two-flow heat exchanger containing a second hot gas circuit of the coolant and a cold water circuit of the coolant, a cooler-separator and a multi-stage compressor with intermediate cooling,the outlet of the cold steam circuit of the coolant of the gas-water two-flow heat exchanger is connected to a high-pressure steam turbine, the outlet of the high-pressure steam turbine is connected to a low-pressure steam turbine, the high-pressure steam turbine and the low-pressure steam turbine are located on a common shaft and are mechanically connected to an electric generator, the first outlet of the low-pressure steam turbine is connected to the first inlet of the first network heater, the second outlet of the low-pressure steam turbine is connected to the first inlet of the deaerator, the third outlet of the low-pressure steam turbine is connected to the inlet of the steam condenser, the outlet of which is connected to the inlet of the condensate pump, the outlet of which is connected to the second inlet of the deaerator, the third inlet of the deaerator is connected via a condensate circuit to the first outlet of the first network heater, the outlet of the deaerator is connected to the inlet of the feed pump,the output of which is connected to the input of the cold steam circuit of the coolant of the gas-water two-flow heat exchanger of the waste heat boiler, the output of the cold water circuit of the coolant of the gas-air two-flow heat exchanger is connected to the first input of the first mixing point, the second output of the first network heater is connected to the second input of the first mixing point, the first output of the second network heater is connected to the third input of the first mixing point, the output of the first mixing point is connected to the heat consumer, the output of which is connected to the network pump, the output of the network pump is connected to the second mixing point, the first output of the second mixing point is connected to the cold water circuit of the coolant of the gas-air two-flow heat exchanger, the second output of the second mixing point is connected to the second input of the first network heater, the third output of the second mixing point is connected to the first input of the second network heater,the first outlet of the cooler-separator is connected to a multi-stage compressor with intermediate cooling, the second outlet of the cooler-separator is connected to the compressor, characterized in that it is provided with first and second air circuits, wherein the second outlet of the air separation unit is connected to the second inlet of the second network heater by the first air circuit, the second outlet of the second network heater is connected to the inlet of the air separation unit by the second air circuit.,

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