CN104791204A - Combined power generation system with geothermal heating, fuel gas and supercritical carbon dioxide - Google Patents

Abstract

The invention discloses a geothermal, gas and supercritical carbon dioxide combined power generation system, including a geothermal heating system, a gas heating system and a supercritical carbon dioxide recompression Brayton cycle power generation system. The invention provides an energy source for the supercritical carbon dioxide recompression Brayton cycle through the geothermal heating system and the gas heating system. The supercritical carbon dioxide fluid first exchanges heat with the geothermal heating system, and when heated to a certain temperature, it enters the gas heating system for Secondary heating, the supercritical carbon dioxide fluid heated to the turbine inlet temperature and pressure is used as the working medium of the supercritical carbon dioxide recompression Brayton cycle to drive the turbine to do work, and the turbine drives the generator set to generate electricity. The invention provides a new idea for the utilization of geothermal energy and the application of supercritical carbon dioxide recompression Brayton power cycle.

Description

A geothermal, gas and supercritical carbon dioxide combined power generation system

Technical field:

The invention relates to a geothermal, gas and supercritical carbon dioxide combined power generation system, which is used for the utilization of geothermal energy and the application of supercritical carbon dioxide recompression Brayton power cycle.

Background technique:

In recent years, with the development of industry, the problems caused by a large amount of energy consumption have become increasingly prominent. The accelerated consumption of fossil fuels has brought about many environmental problems, such as global warming, acid rain, ozone layer destruction, and land and ocean pollution.

Therefore, whether it is viewed from the perspective of taking the road of sustainable economic and social development and protecting the ecological environment of the earth on which human beings depend, or starting from solving the reality of energy supply for about 2 billion people without electricity in the world and special purposes, It is of great strategic significance to develop and utilize new and renewable energy sources. According to the 2007 data of the United Nations World Energy Assessment Report, the annual utilization factor of wind power in 2007 was 21% (21% of the time in a year was at work), the utilization factor of solar energy was 14%, and the utilization factor of geothermal energy was 72%. , which is 3.4 times that of wind energy and 5.1 times that of solar energy. Compared with other renewable energy sources, geothermal energy has low investment and operating costs, high utilization coefficient, almost unaffected by weather and climate, and stable power generation, making geothermal energy very competitive. Strengthening the research and utilization of geothermal energy has application potential and significance.

Utilizing the sudden change of physical properties in the quasi-critical region of supercritical fluid, the operating point of the compressor is set in the high-density area near the pseudo-critical temperature, and the operating point of the heat exchanger is set in the low-density area after the pseudo-critical temperature, which can ensure the cooling of the gas. Under the premise, the compression power consumption is reduced to achieve higher efficiency. This property of supercritical fluids has obvious advantages as working fluids for energy conversion. Due to its relatively moderate critical pressure (7.38MPa), carbon dioxide (CO ₂ ) has good stability and physical properties. It is considered to be one of the most promising energy transfer and energy conversion working fluids. Since supercritical carbon dioxide (S-CO ₂ ) has a high density and no phase change within a certain range of operating parameters, the structure of power system equipment such as compressors and gas turbines using supercritical carbon dioxide (S-CO ₂ ) Compact and small in size. For example, a supercritical carbon dioxide Brayton cycle system that generates 20MW of electricity takes up only four cubic meters of space. Supercritical carbon dioxide (S-CO ₂ ) Brayton cycle gas turbines are commonly used in large-scale thermal and nuclear power generation, including next-generation power reactors, with the goal of eventually replacing steam-driven Rankine cycle turbines (lower efficiency, volume about 30 times that of a supercritical carbon dioxide gas turbine).

Invention content:

The object of the present invention is to provide a kind of can improve energy utilization efficiency, provide stable power supply, simultaneously provide the utilization of geothermal energy and the application of supercritical carbon dioxide recompression (S-CO ₂ ) Brayton (Brayton) power cycle A geothermal, gas and supercritical carbon dioxide combined power generation system.

In order to achieve the above object, the present invention adopts following technical scheme to realize:

A geothermal, gas and supercritical carbon dioxide combined power generation system, including a geothermal heating system, a gas heating system and a supercritical carbon dioxide recompression Brayton cycle power generation system; wherein,

The geothermal heating system includes a geothermal recovery well, the outlet of the geothermal recovery well communicates with the inlet of the water pump, the outlet of the water pump connects with the inlet of the hot water pump, and the outlet of the hot water pump connects with the geothermal water heated by the geothermal energy heat exchanger. Inlet connection, the geothermal water outlet of the geothermal energy heating heat exchanger is connected to the inlet of the reinjection well;

The gas heating system includes an injector, the outlet of the injector is connected to the inlet of the combustion chamber, the outlet of the combustion chamber is connected to the gas inlet of the gas heating heat exchanger, the gas outlet of the gas heating heat exchanger is connected to the gas exhaust The inlet connection of the receiving device;

The supercritical carbon dioxide recompression Brayton cycle power generation system includes a turbine, the outlet of the turbine is connected to the high temperature side supercritical carbon dioxide fluid inlet of the high temperature regenerator, and the high temperature side supercritical carbon dioxide fluid outlet of the high temperature regenerator is connected to the The inlet of the supercritical carbon dioxide fluid on the high temperature side of the low temperature regenerator is connected, the outlet of the supercritical carbon dioxide fluid on the high temperature side of the low temperature regenerator is divided into two routes, one is connected to the inlet of the recompressor unit, and the outlet of the recompressor unit is connected to the The low temperature side is connected to the supercritical carbon dioxide fluid inlet, the other is connected to the condenser inlet, the condenser outlet is connected to the main compressor unit inlet, the main compressor unit outlet is connected to the low temperature side supercritical carbon dioxide fluid inlet of the low temperature regenerator, The low-temperature side supercritical carbon dioxide fluid outlet of the low-temperature regenerator is connected with the low-temperature side supercritical carbon dioxide fluid inlet of the high-temperature regenerator, and the low-temperature side supercritical carbon dioxide fluid outlet of the high-temperature regenerator is connected with the supercritical carbon dioxide of the geothermal energy heating heat exchanger The fluid inlet is connected, the inlet of the turbine is connected with the supercritical carbon dioxide fluid outlet of the gas heating heat exchanger, and the turbine is used to drive the generating set to generate electricity.

The further improvement of the present invention lies in that: the injector is equipped with three inlets, respectively leading into fuel, oxidant and water, and the three propellants of fuel, oxidant and water all enter the combustion chamber through the injector to directly participate in combustion, and the gas generating device adopts direct Combustion type three-component combustion method, forming a mixed gas with adjustable temperature and other parameters.

The further improvement of the present invention is that: the supercritical carbon dioxide recompression Brayton cycle power generation system uses supercritical carbon dioxide as a working medium.

The further improvement of the present invention is: a first control valve is installed on the connection pipeline between the outlet of the hot water pump and the geothermal water inlet of the geothermal energy heating heat exchanger, which is used to control the flow of geothermal water entering the geothermal energy heating heat exchanger; The second control valve and the third control valve are installed on the connection pipeline between the geothermal water outlet of the thermal energy heating heat exchanger and the inlet of the reinjection well to control the flow of geothermal water flowing out of the geothermal energy heating heat exchanger and the return flow. The flow rate of well filling; a fourth control valve is installed between the outlet of the suction pump and the inlet connection pipeline of the hot water pump and the connection pipeline between the second control valve and the third control valve to prevent the geothermal energy from heating the heat exchanger. In case of failure, the geothermal water can be returned to the recharge well smoothly.

The further improvement of the present invention is: when the system works normally, the first control valve, the second control valve and the third control valve are opened, and the fourth control valve is closed. , into the pipeline leading to the geothermal energy heating heat exchanger, through the work of the hot water pump, enter the geothermal energy heating heat exchanger to exchange heat with the supercritical carbon dioxide fluid flowing out of the high temperature regenerator, and the geothermal energy after heat exchange The water returns to the recharge well through the backflow channel to form a loop. The second control valve and the third control valve on the backflow channel control the return flow of geothermal water. When the system fails, the first control valve and the third control valve are closed. The second control valve opens the third control valve and the fourth control valve. At this time, the geothermal water does not pass through the geothermal energy heating heat exchanger, but directly returns to the reinjection well;

Fuel, oxidizer and water are three propellants that enter the gas generator through the injector. After premixing, they enter the combustion chamber and directly participate in combustion to form high-temperature mixed gas. The mixed gas enters the gas heating heat exchanger through the outlet of the combustion chamber and The supercritical carbon dioxide fluid flowing out of the geothermal energy heating heat exchanger is used for heat exchange, and the supercritical carbon dioxide fluid is reheated, and the mixed gas after heat exchange enters the gas exhaust receiving device for processing;

The carbon dioxide fluid at the outlet of the turbine first enters the high-temperature regenerator for heat release, and then enters the low-temperature regenerator for heat exchange again. Then, part of the carbon dioxide fluid is directly sent to the recompressor unit to be compressed, and the other part of the carbon dioxide fluid first enters the condenser for further heat exchange. After cooling, it enters the main compressor unit for compression, and then reheats through the low-temperature regenerator to the same temperature as the carbon dioxide fluid directly compressed by the recompressor unit. After the two fluids are mixed, they flow through the high-temperature regenerator together. The geothermal heating heat exchanger and the gas heating heat exchanger finally flow into the turbine to do work, and the turbine drives the generator set to generate electricity, forming a closed cycle.

Compared with the prior art, the present invention provides heat for the supercritical carbon dioxide (S-CO ₂ ) recompression Brayton (Brayton) cycle through the geothermal heating system and the gas heating system. The supercritical carbon dioxide fluid first exchanges heat with the geothermal heating system, After being heated to a certain temperature, it enters the gas heating system for heat exchange. The supercritical carbon dioxide fluid heated to the temperature and pressure of the turbine inlet is used as the supercritical carbon dioxide (S-CO ₂ ) recompression Brayton (Brayton) cycle. The working fluid drives the turbine to do work, and the turbine drives the generator set to generate electricity. In the whole combined power generation system, the thermal energy generated by geothermal energy and gas combustion is used as the heat source of the supercritical carbon dioxide (S-CO ₂ ) recompression Brayton (Brayton) cycle power generation system to realize the supercritical carbon dioxide (S-CO ₂ ) recompression Brayton (Brayton) power cycle, through the carbon dioxide turbine to drive the generator set to generate electricity, which improves energy utilization efficiency and provides a stable power supply. This system provides a new idea for the utilization of geothermal energy and the application of supercritical carbon dioxide recompression (S-CO ₂ ) Brayton (Brayton) power cycle.

Description of drawings:

Fig. 1 is a structural representation of the present invention;

In the figure: 1. Geothermal recovery well, 2. Reinjection well, 3. Suction pump, 4. Hot water pump, 5. Geothermal energy heating heat exchanger, 6. Injector, 7. Combustion chamber, 8. Gas heating exchange Heater, 9. Gas exhaust receiving device, 10. High temperature regenerator, 11. Low temperature regenerator, 12. Condenser, 13. Main compressor unit, 14. Recompressor unit, 15. Turbine, 16. Power generation Unit, F1, the first control valve, F2, the second control valve, F3, the third control valve, F4, the fourth control valve.

Detailed ways:

The present invention will be described in detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the present invention is a geothermal, gas and supercritical carbon dioxide combined power generation system, including a geothermal heating system, a gas heating system and a supercritical carbon dioxide (S-CO ₂ ) recompression Brayton cycle power generation system.

Wherein, the geothermal heating system includes a geothermal recovery well 1, a recharge well 2, a water pump 3, a hot water pump 4, a geothermal energy heating heat exchanger 5, a first control valve F1, a second control valve F2, and a third control valve F3 With the fourth control F4, the outlet of the geothermal extraction well 1 is connected with the inlet of the water pump 3, the outlet of the water pump 3 is connected with the inlet of the hot water pump 4, and the outlet of the hot water pump 4 is connected with the geothermal water heated by the geothermal energy heat exchanger 5. Inlet connection, the geothermal water outlet of the geothermal energy heating heat exchanger 5 is connected to the inlet of the recharge well 2, and the outlet of the hot water pump 4 is connected to the geothermal water inlet of the geothermal energy heating heat exchanger 5. A first control is installed on the pipeline. Valve F1, a second control valve F2 and a third control valve F3 are installed on the connection pipeline between the geothermal water outlet of the geothermal energy heating heat exchanger 5 and the inlet of the recharge well 2; the outlet of the water pump 3 and the inlet of the hot water pump 4 A fourth control valve F4 is installed between the connecting pipeline and the connecting pipeline between the second control valve F2 and the third control valve F3; when the system is working normally, open the first control valve F1, the second control valve F2 and the third control valve F4 The control valve F3 closes the fourth control valve F4. At this time, the hot water in the geothermal exploitation well, through the action of the water pump 3, enters the pipeline leading to the geothermal energy heating heat exchanger 5, and enters the ground through the work of the hot water pump 4. The thermal energy heating heat exchanger 5 exchanges heat with the supercritical carbon dioxide fluid flowing out of the high-temperature regenerator 10, and the geothermal water after heat exchange returns to the recharge well 2 through the return channel to form a loop. The second control valve F2 and the third control valve F3 are used to control the return flow of geothermal water. When the system fails, the first control valve F1 and the second control valve F2 are closed, and the third control valve F3 and the fourth control valve are opened. Control valve F4. At this time, the geothermal water returns directly to the reinjection well 2 without passing through the heat exchanger 5 heated by geothermal energy.

The gas heating system includes an injector 6, a combustion chamber 7 and a gas heating heat exchanger 8. The outlet of the injector 6 is connected to the inlet of the combustion chamber 7, and the outlet of the combustion chamber 7 is connected to the gas heating heat exchanger 8. The gas inlet is connected, the gas outlet of the gas heating heat exchanger 8 is connected to the inlet of the gas exhaust receiving device 9; the three propellants of fuel, oxidant and water enter the gas generator through the injector 6, and enter the combustion chamber after premixing 7 directly participates in combustion to form a high-temperature mixed gas, and the mixed gas enters the gas heating heat exchanger 8 through the outlet of the combustion chamber 7 to exchange heat with the supercritical carbon dioxide fluid flowing out of the geothermal energy heating heat exchanger 5, and the supercritical carbon dioxide The fluid is reheated, and the mixed gas after heat exchange enters the gas exhaust receiving device 9 for processing. The invention adopts a direct combustion type three-component gas generator, which can form a mixed gas whose temperature and other parameters can be adjusted in a wide range, and the temperature of the gas in the combustion chamber is lower, and the thermal protection is simpler, eliminating the need for a cooling room and a gas generator. While working efficiently and reliably, the structure is also simpler.

The supercritical carbon dioxide (S-CO ₂ ) recompression Brayton (Brayton) cycle power generation system includes a high temperature regenerator 10, a low temperature regenerator 11, a condenser 12, a main compressor unit 13, a recompressor unit 14, Turbine 15 and generator set 16, the outlet of turbine 15 is connected with the high temperature side supercritical carbon dioxide fluid inlet of high temperature regenerator 10, the high temperature side supercritical carbon dioxide fluid outlet of high temperature regenerator 10 is connected with the high temperature of low temperature regenerator 11 The side supercritical carbon dioxide fluid inlet is connected, and the high temperature side supercritical carbon dioxide fluid outlet of the low temperature regenerator 11 is connected to other devices in two ways, one is connected to the inlet of the recompressor unit 14, and the outlet of the recompressor unit 14 is connected to the high temperature regenerator The low-temperature side of 10 is connected to the supercritical carbon dioxide fluid inlet, and the other is connected to the inlet of the condenser 12, the outlet of the condenser 12 is connected to the inlet of the main compressor unit 13, and the outlet of the main compressor unit 13 is connected to the low-temperature side of the low-temperature regenerator 11 The supercritical carbon dioxide fluid inlet is connected, the low-temperature side supercritical carbon dioxide fluid outlet of the low-temperature regenerator 11 is connected with the low-temperature side supercritical carbon dioxide fluid inlet of the high-temperature regenerator 10, and the low-temperature side supercritical carbon dioxide fluid outlet of the high-temperature regenerator 10 is connected to the The inlet of the geothermal energy heating heat exchanger 5 is connected, and the inlet of the turbine 15 is connected with the outlet of the gas heating heat exchanger 8; the carbon dioxide fluid at the outlet of the turbine 15 first enters the high-temperature regenerator 10 for heat release, and then enters the low-temperature regenerator The condenser 11 performs heat exchange again, and then, a part of the carbon dioxide fluid is directly sent to the recompressor unit 14 to be compressed, and the other part of the carbon dioxide fluid first enters the condenser 12 for cooling, and then enters the main compressor unit for compression, and then passes through the low-temperature reheating unit again. The reheater 11 is reheated to the same temperature as the carbon dioxide fluid directly compressed by the recompressor unit 13, and the two streams are mixed and then flow through the high temperature regenerator 10, the geothermal heating heat exchanger 5 and the gas heating heat exchanger 8, and finally It flows into the turbine 15 to perform work, and the turbine 15 drives the generator set 16 to generate electricity, forming a closed cycle.

Compared with other renewable energy sources, geothermal energy has low investment and operating costs, high utilization coefficient, almost unaffected by weather and climate, stable power generation and other advantages, making geothermal energy very competitive.

The direct-combustion three-component gas generator directly mixes and burns the traditional two-component propellant and the temperature-regulating medium to form a mixed gas whose temperature and other parameters can be adjusted in a wide range, and the gas temperature in the combustion chamber is lower and the thermal protection is better. Simple, the cooling chamber is omitted, and the structure of the gas generator is simpler while it works efficiently and reliably.

In the supercritical carbon dioxide (S-CO ₂ ) Brayton (Brayton) cycle power system of the present invention, since supercritical carbon dioxide (S-CO ₂ ) has a relatively large density and no phase change within a certain range of operating parameters, the supercritical carbon dioxide (S-CO 2 ) Carbon dioxide (S-CO ₂ ) as the working fluid of compressors, gas turbines and other power system equipment is compact in structure and small in size, which not only saves cost but also saves space.

Claims (5)

1. The utility model provides a geothermol power, gas and supercritical carbon dioxide combined power generation system which characterized in that: the system comprises a geothermal heating system, a gas heating system and a supercritical carbon dioxide recompression Brayton cycle power generation system; wherein,

the geothermal heating system comprises a geothermal exploitation well (1), wherein an outlet of the geothermal exploitation well (1) is communicated with an inlet of a water pump (3), an outlet of the water pump (3) is connected with an inlet of a hot water pump (4), an outlet of the hot water pump (4) is connected with a geothermal water inlet of a geothermal energy heating heat exchanger (5), and a geothermal water outlet of the geothermal energy heating heat exchanger (5) is connected with an inlet of a recharge well (2);

the gas heating system comprises an injector (6), an outlet of the injector (6) is connected with an inlet of a combustion chamber (7), an outlet of the combustion chamber (7) is connected with a gas inlet of a gas heating heat exchanger (8), and a gas outlet of the gas heating heat exchanger (8) is connected with an inlet of a gas exhaust receiving device (9);

the supercritical carbon dioxide recompression Brayton cycle power generation system comprises a turbine (15), wherein an outlet of the turbine (15) is connected with a supercritical carbon dioxide fluid inlet at the high temperature side of a high-temperature heat regenerator (10), a supercritical carbon dioxide fluid outlet at the high temperature side of the high-temperature heat regenerator (10) is connected with a supercritical carbon dioxide fluid inlet at the high temperature side of a low-temperature heat regenerator (11), a supercritical carbon dioxide fluid outlet at the high temperature side of the low-temperature heat regenerator (11) is divided into two paths, one path is connected with an inlet of a recompression unit (14), an outlet of the recompression unit (14) is connected with a supercritical carbon dioxide fluid inlet at the low temperature side of the high-temperature heat regenerator (10), the other path is connected with an inlet of a condenser (12), an outlet of the condenser (12) is connected with an inlet of a main compressor unit (13), an outlet of the main compressor unit (13) is connected with a supercritical carbon dioxide fluid inlet at the low temperature, the low-temperature side supercritical carbon dioxide fluid outlet of the low-temperature regenerator (11) is connected with the low-temperature side supercritical carbon dioxide fluid inlet of the high-temperature regenerator (10), the low-temperature side supercritical carbon dioxide fluid outlet of the high-temperature regenerator (10) is connected with the supercritical carbon dioxide fluid inlet of the geothermal energy heating heat exchanger (5), the inlet of the turbine (15) is communicated with the supercritical carbon dioxide fluid outlet of the gas heating heat exchanger (8), and the turbine (15) is used for driving the generator set (16) to generate power.

2. The combined geothermal, gas and supercritical carbon dioxide power generation system of claim 1, wherein: the injector (6) is provided with three inlets, fuel, oxidant and water are respectively introduced, the fuel, oxidant and water propellant enter the combustion chamber (7) through the injector (6) to directly participate in combustion, and the gas generating device adopts a direct combustion type three-component combustion mode to form mixed gas with adjustable temperature and other parameters.

3. The combined geothermal, gas and supercritical carbon dioxide power generation system of claim 1, wherein: the supercritical carbon dioxide recompression Brayton cycle power generation system uses supercritical carbon dioxide as a working medium.

4. A geothermal, gas and supercritical carbon dioxide cogeneration system according to any one of claims 1 to 3, characterized in that: a first control valve (F1) is arranged on a connecting pipeline between the outlet of the hot water pump (4) and the geothermal water inlet of the geothermal energy heating heat exchanger (5) and is used for controlling the flow of the geothermal water entering the geothermal energy heating heat exchanger (5); a second control valve (F2) and a third control valve (F3) are arranged on a geothermal water outlet of the geothermal energy heating heat exchanger (5) and an inlet connecting pipeline of the recharging well (2) and are respectively used for controlling the flow of geothermal water flowing out of the geothermal energy heating heat exchanger (5) and the flow of geothermal water returning to the recharging well (2); a fourth control valve (F4) is arranged between the outlet of the water pump (3) and the inlet connecting pipeline of the hot water pump (4) and the connecting pipeline of the second control valve (F2) and the third control valve (F3) and is used for preventing geothermal energy from smoothly returning to the recharging well (2) when the geothermal energy heating heat exchanger (5) breaks down.

5. The combined geothermal, gas and supercritical carbon dioxide power generation system of claim 4, wherein: when the system works normally, a first control valve (F1), a second control valve (F2) and a third control valve (F3) are opened, a fourth control valve (F4) is closed, at the moment, hot water in the geothermal exploitation well enters a pipeline communicated with a geothermal energy heating heat exchanger (5) under the action of a water suction pump (3), the hot water enters the geothermal energy heating heat exchanger (5) to exchange heat with supercritical carbon dioxide fluid flowing out of a high-temperature heat regenerator (10) through the work of a hot water pump (4), geothermal water after heat exchange returns to a recharge well (2) through a return channel to form a loop, the second control valve (F2) and the third control valve (F3) on the return channel control the flow rate of the return flow of the geothermal water, when the system fails, the first control valve (F1) and the second control valve (F2) are closed, the third control valve (F3) and the fourth control valve (F4) are opened, at the moment, the geothermal water directly returns to the recharging well (2) without passing through the geothermal energy heating heat exchanger (5);

the fuel, oxidant and water propellant enter the fuel gas generator through the injector (6), after premixing, the fuel gas enters the combustion chamber (7) to directly participate in combustion to form high-temperature mixed fuel gas, the mixed fuel gas enters the fuel gas heating heat exchanger (8) through the outlet of the combustion chamber (7) to exchange heat with the supercritical carbon dioxide fluid flowing out of the geothermal energy heating heat exchanger (5), the supercritical carbon dioxide fluid is heated for the second time, and the mixed fuel gas after heat exchange enters the fuel gas exhaust receiving device (9) to be processed;

the carbon dioxide fluid at the outlet of the turbine (15) enters the high-temperature heat regenerator (10) to release heat, and then enters the low-temperature heat regenerator (11) to exchange heat again, then, one part of the carbon dioxide fluid directly leads to the recompression unit (14) to be compressed, the other part of the carbon dioxide fluid enters the condenser (12) to be cooled first, and then enters the main compressor unit to be compressed, then, the temperature of the carbon dioxide fluid directly compressed by the recompression unit (13) is reached through the heat regeneration of the low-temperature heat regenerator (11) again, the two parts of the carbon dioxide fluid are mixed and then flow through the high-temperature heat regenerator (10), the geothermal heating heat exchanger (5) and the gas heating heat exchanger (8) together, and finally, the carbon dioxide fluid flows into the turbine (15) to do work, the turbine (15) drives the.