A coupled power generation system and method based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity

Abstract

This invention discloses a multi-energy complementary coupled power generation system and method based on geothermal ORC-LNG cold energy-seawater source, belonging to the technical field of geothermal energy development and utilization and LNG cold energy utilization. It includes a geothermal ORC power generation system, an LNG vaporization and heating system, and a heating system. The geothermal ORC power generation system is connected to the LNG vaporization and heating system, providing a heat source for the LNG vaporization and heating system, and the LNG vaporization and heating system providing a cold source for the geothermal ORC power generation system. Both the geothermal ORC power generation system and the LNG vaporization and heating system are connected to the heating system. This multi-energy complementary coupled power generation-gas supply system simultaneously meets the cold and heat requirements of ORC power generation condensation and LNG vaporization, improving the overall performance and efficiency of the power generation-gas supply coupled system while meeting natural gas supply requirements.

Description

Technical Field

[0001] This invention belongs to the technical field of geothermal energy development and utilization and LNG cold energy utilization, specifically involving a coupled power generation system and method based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity. Background Technology

[0002] The large-scale development and utilization of geothermal energy can play a crucial role in meeting global energy demand growth and achieving decarbonization goals. In this context, maximizing the efficiency of geothermal utilization is essential to fully realizing its decarbonization potential. Liquefied natural gas (LNG) must be vaporized and heated before it can be used by users. LNG can provide a significant amount of cooling energy by heating it from -162°C to room temperature, approximately 830 kJ / kg, or about 231 kWh / t. The rational utilization of this cooling energy will bring significant economic and environmental benefits.

[0003] The most common geothermal power generation method is the Organic Rankine Cycle (ORC). Currently, the installed capacity and efficiency of geothermal ORC power generation are relatively low. From a thermodynamic perspective, the most effective measure to improve the power generation performance of the geothermal cycle is to increase the heat source temperature and decrease the cold source temperature. The heat source temperature is limited by resource endowment and cannot be solved through technical means; therefore, minimizing the cold source temperature becomes crucial for improving system performance. A single ORC system is limited by ambient temperature, resulting in limited reduction in cold source temperature. Combining the demand for a low-temperature cold source during ORC power generation condensation with the demand for a high-temperature heat source during LNG vaporization and heating, constructing an ORC-LNG cold energy coupled power generation system is gradually becoming a new trend.

[0004] Existing research discloses numerous coupling schemes and technologies for "ORC power generation with medium- and low-temperature heat sources and LNG cold energy utilization." Patent CN109098809A, based on the existing ORC cycle, improves the LNG cold energy recovery and utilization method, disclosing an ORC power generation system utilizing LNG cold energy and industrial waste heat. By introducing a three-fluid heat exchanger and a regenerator, the heat load of the evaporator is reduced, effectively improving the efficiency of the ORC power generation system. However, constrained by the demand for natural gas supply to users and the lack of other heat sources input during LNG vaporization, the ORC condensation temperature is relatively high, and the power generation efficiency of the ORC system is still not ideal. Patent CN110185509A discloses a thermal power plant coupled with LNG cold energy power generation system and method, introducing seawater / circulating water as an auxiliary heat source for LNG vaporization, which further reduces the ORC system condensation temperature. The heated LNG is then fed into the expander to generate electricity, improving the overall output of the energy system. However, while existing ORC and LNG coupled power generation technologies can improve the overall system efficiency and power output to varying degrees, their adaptability is weak, and they cannot make corresponding adjustments to address changing environmental conditions. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a coupled power generation system and method based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity. This addresses the problems of existing coupled systems having relatively simple operation strategies and schemes, failing to consider dynamic matching between subsystems, and being unable to adjust operation strategies according to dynamic changes in ambient temperature over long-term operation; and the direct use of ORC power generation system condensation heat as the LNG vaporization heating heat source, which limits the power generation system's condensation temperature to ensure natural gas supply temperature, thus restricting the power output of the power generation system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] Firstly, a coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity includes a geothermal ORC power generation system, an LNG gasification and heating system, and a heating system;

[0008] The geothermal ORC power generation system is connected to the LNG vaporization and heating system. The geothermal ORC power generation system provides a heat source for the LNG vaporization and heating system, and the LNG vaporization and heating system provides a cold source for the geothermal ORC power generation system. The geothermal ORC power generation system and the LNG vaporization and heating system are respectively connected to the heating system.

[0009] Furthermore, the geothermal ORC power generation system includes a geothermal well group and a surface working fluid circulation system; the geothermal well group is connected to the surface working fluid circulation system.

[0010] Furthermore, the geothermal well group includes a production well and a reinjection well; the outlet of the production well is connected to a distributor; the outlet of the distributor is divided into two paths, one of which is connected to the heat pump condenser in the heating system through a valve; the other path is connected to the water-side inlet of the evaporator in the surface working fluid circulation system, and the two paths finally converge at the collector and are connected to the reinjection well.

[0011] The ground working fluid circulation system includes a preheater, evaporator, turbine, generator, condenser, and working fluid pump;

[0012] The preheater uses seawater as its heating source. The preheater inlet is connected to the outlet of the working fluid pump, and the preheater outlet is connected to the evaporator inlet. The evaporator uses geothermal water as its heating source. The evaporator working fluid outlet is connected to the turbine, and the evaporator water-side outlet is connected to the reinjection well. The turbine is coaxially connected to the generator, the turbine outlet is connected to the condenser, and the condenser outlet is connected to the working fluid pump.

[0013] Furthermore, the LNG vaporization and heating system includes an LNG storage tank, an LNG transfer pump, and an LNG vaporization device;

[0014] The LNG storage tank outlet is connected to the condenser outlet via an LNG transfer pump, and the LNG outlet of the condenser is connected to the inlet of the LNG vaporization unit. The LNG vaporization unit is heated by a seawater source heat pump or geothermal water in winter, and directly heated by a seawater source in other seasons.

[0015] Furthermore, the heating system is a seawater source heating system, which includes a seawater source heat pump heating system and a seawater source direct heating system.

[0016] The seawater source heat pump heating system includes a distributor II, through which seawater enters. Distributor II is connected to the water-side inlet of the heat pump evaporator via valve 6. The water-side outlet of the heat pump evaporator is connected to a collector III. The evaporator working fluid outlet is connected to the compressor inlet. The compressor outlet is connected to the heat pump condenser via valve 7 and collector IV. The condenser working fluid outlet is connected to the evaporator inlet via distributor IV and a throttling valve. The condenser circulating water outlet is connected to valve 4 and collector II. The outlet of collector II is connected to an LNG vaporization unit. The outlet of the LNG vaporization unit is connected to a circulating pump, which is then connected to the heat pump condenser via distributor III and valve III.

[0017] The seawater source direct heating system includes a liquid collector two; another path of the liquid separator two is connected to the liquid collector two through a valve two, and the outlet of the liquid collector two is connected to the LNG vaporization device. The outlet of the LNG vaporization device is connected to the liquid collector three through a circulating pump, a liquid separator three, and a valve five in sequence.

[0018] Furthermore, the heating system includes a seawater source direct heating system and a geothermal water heating system;

[0019] The geothermal heating system includes a heat pump condenser; a distributor is connected to the inlet of the heat pump condenser via a valve and a collector; the circulating water outlet of the heat pump condenser is connected to the inlet of the collector via a valve; the outlet of the collector is connected to the LNG vaporization device; the outlet of the LNG vaporization device is connected to the circulating pump; and the circulating water outlet is connected to the heat pump condenser via a distributor and a valve to complete one water cycle.

[0020] The seawater source direct heating system includes a liquid collector 2, the inlet of which is connected to a valve 2, and the outlet of which is connected to an LNG vaporization device. The outlet of the vaporization device passes through a circulating pump, a distributor 3, and a valve 5 in sequence. Seawater is sent into the LNG vaporization device through valve 2 and liquid collector 2.

[0021] Secondly, a coupled power generation method based on a geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system, and the working process of the geothermal ORC power generation system specifically includes:

[0022] The geothermal water from the production well is fed into the water side of the evaporator, where it releases heat to the organic working fluid and is then reinjected through the reinjection well. The organic working fluid absorbs heat and vaporizes into a saturated gaseous state in the evaporator. The vaporized working fluid steam is then sent to the turbine for expansion to drive the generator and generate electricity. The exhaust steam at the turbine outlet is completely condensed into a liquid state in the condenser. It is then pressurized to the evaporation pressure by the working fluid pump and sent to the preheater to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to the evaporator to complete one ORC power generation cycle.

[0023] The workflow of an LNG vaporization and heating system includes:

[0024] The cryogenic LNG in the LNG storage tank is pumped into the condenser to absorb the condensation heat of the power generation working fluid, thus completing the LNG preheating. The preheated LNG is then sent into the LNG vaporization unit to absorb heat and vaporize, where the heat required for vaporization comes from the heating system.

[0025] Furthermore, the workflow of a seawater source heat pump heating system within a heating system specifically includes:

[0026] Close valves 2 and 5, and open valves 3, 4, and 6. Seawater is fed into the heat pump evaporator through distributor 2 and valve 6, transferring heat to the heat pump working fluid and causing it to completely vaporize. The vaporized working fluid is pressurized to condensing pressure by the compressor and sent into the heat pump condenser, releasing heat to the circulating water. It then passes through the throttling valve to reduce temperature and pressure, and finally flows into the evaporator, completing one heat pump cycle. The circulating water absorbs heat and increases in temperature in the heat pump condenser, then passes through valve 4 and collector 2 and is sent into the LNG vaporization unit, transferring heat to the LNG. It then passes through the circulating pump, distributor 3, and valve 3 and is sent into the heat pump condenser, completing one water cycle.

[0027] The workflow of a direct seawater heating system within a heating system specifically includes:

[0028] Close valves 3, 4, and 6, and open valves 2 and 5; seawater is sent into the LNG vaporization unit through separator 2, valve 2, and collector 2, directly transferring heat to the cryogenic LNG to vaporize it; the seawater after releasing heat is discharged through the circulation pump, separator 3, valve 5, and collector 3.

[0029] Thirdly, a coupled power generation method based on a geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system, the working process of the geothermal ORC power generation system specifically includes:

[0030] The geothermal water from the production well is split into two streams by a distributor. One stream is sent to the water side of the evaporator, where it releases heat to the organic working fluid. After being mixed with the other stream through a collector, the mixture is reinjected through the reinjection well. The organic working fluid absorbs heat and vaporizes into a saturated gaseous state in the evaporator. The vaporized working fluid steam is then sent to the turbine for expansion, which drives the generator to generate electricity. The exhaust steam from the turbine outlet is completely condensed into a liquid state in the condenser. It is then pressurized to the evaporation pressure by the working fluid pump and sent to the preheater to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to the evaporator to complete one ORC power generation cycle.

[0031] The workflow of an LNG vaporization and heating system includes:

[0032] The cryogenic LNG in the LNG storage tank is pumped into the condenser to absorb the condensation heat of the power generation working fluid, thus completing the LNG preheating. The preheated LNG is then sent into the LNG vaporization unit to absorb heat and vaporize, with the heat required for vaporization coming from the heating system.

[0033] Furthermore, the workflow of the geothermal heating system within the heating system specifically includes:

[0034] Close valves 2, 5, and 7 and the throttle valve, and open valves 1, 3, and 4; geothermal water is sent into the heat pump condenser, releasing heat to the circulating water, and then mixed with another stream in collector 1 before being injected into the reinjection well; after absorbing heat and increasing temperature in the heat pump condenser, the circulating water passes through valve 4 and collector 2 in sequence and is then sent into the LNG vaporization unit to transfer heat to the LNG, and then passes through the circulating pump, distributor 3, and valve 3 back into the heat pump condenser to complete one water cycle;

[0035] The workflow of a direct seawater heating system within a heating system specifically includes:

[0036] Close valves 1, 3, 4, and 6, and open valves 2 and 5. Seawater is sent into the LNG vaporization unit through valve 2 and collector 2, directly transferring heat to the cryogenic LNG to vaporize it. The seawater that has released heat is discharged from the heating system through the circulation pump, distributor 3, and valve 5.

[0037] The coupled power generation system and method based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity provided by this invention has the following beneficial effects:

[0038] 1. The multi-energy complementary coupling power generation-gas supply system of the present invention simultaneously meets the cold and heat requirements of ORC power generation condensation and LNG gasification, and improves the overall performance and efficiency of the power generation-gas supply coupling system while meeting the natural gas supply requirements.

[0039] 2. This invention heats LNG using a segmented heater, utilizing the cold energy of the LNG's low-temperature section. Compared to the case where all the cold energy is used to cool the working fluid in the power generation cycle in the condenser, the LNG uses the low-temperature section cold energy in the ORC condenser as a cold source for the power generation system, which can further reduce the condensation temperature and turbine exhaust pressure of the ORC system and improve the power output of the ORC power generation system.

[0040] 3. The multi-energy complementary coupling power generation-gas supply system of the present invention uses three different forms of heating for the LNG gasification unit: seawater source heat pump, direct seawater source heating, and direct geothermal water heating. The operating strategy and scheme can be flexibly adjusted according to the location of the project and the seasonal changes in ambient temperature, so that the overall efficiency of the system is in the optimal state. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the framework of the coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity in Embodiment 1 of the present invention.

[0042] Figure 2 This is a schematic diagram of the framework of the coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity in Embodiment 2 of the present invention.

[0043] Figure 3 This is a schematic diagram of the coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity in Embodiment 3 of the present invention.

[0044] Among them, 1-1, production well; 1-2, distributor one; 1-3, valve one; 1-4, collector one; 1-5, recharge well;

[0045] 2-1. Preheater; 2-2. Evaporator; 2-3. Turbine; 2-4. Generator; 2-5. Condenser; 2-6. Working fluid pump;

[0046] 3-1 LNG storage tank; 3-2 LNG transfer pump; 3-3 LNG vaporization unit;

[0047] 4-1. Dispenser II; 4-2. Valve II; 4-3. Collector II; 4-4. Circulating pump; 4-5. Dispenser III; 4-6. Valve III; 4-7. Heat pump condenser; 4-8. Valve IV; 4-9. Valve V; 4-10. Collector III; 4-11. Dispenser IV; 4-12. Throttling valve; 4-13. Heat pump evaporator; 4-14. Valve VI; 4-15. Compressor; 4-16. Valve VII; 4-17. Collector IV. Detailed Implementation

[0048] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0049] Example 1

[0050] This embodiment presents a geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system. This system integrates geothermal ORC power generation, LNG heating and gas supply, and seawater heating into a single system, enabling LNG vaporization and supply while simultaneously developing and utilizing geothermal energy, achieving a "two-in-one" goal. Furthermore, based on the geothermal ORC power generation system, a geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation-gas supply composite system is constructed. This system can address the differences in heat source conditions in the project implementation area and the seasonal variations in ambient temperature under long-term operating conditions. It solves the problem of low operating efficiency in conventional geothermal ORC power generation systems and also addresses the issue of additional heat supply required for LNG vaporization and heating. (Refer to...) Figure 1 Specifically, it includes:

[0051] Geothermal ORC power generation system, LNG vaporization and heating system, and heating system;

[0052] In some embodiments, the geothermal ORC power generation system is connected to the LNG vaporization and heating system, the geothermal ORC power generation system provides a heat source for the LNG vaporization and heating system, and the LNG vaporization and heating system provides a cold source for the geothermal ORC power generation system; the geothermal ORC power generation system and the LNG vaporization and heating system are respectively connected to the heating system.

[0053] In some embodiments, the geothermal ORC power generation system includes a geothermal well group and a surface working fluid circulation system; the geothermal well group is connected to the surface working fluid circulation system.

[0054] In one specific embodiment, the geothermal well group includes a production well 1-1 and a reinjection well 1-5; wherein, the outlet of the production well 1-1 is connected to a distributor 1-2, and the outlet of the distributor 1-2 is divided into two paths, one path is connected to the heat pump condenser 4-7 in the heating system through a valve 1-3 and a collector 4-17; the other path is connected to the water-side inlet of the evaporator 2-2 in the surface working fluid circulation system, and the two paths finally converge at the collector 1-4 and are connected to the reinjection well 1-5;

[0055] In some embodiments, the ground working fluid circulation system includes a preheater 2-1, an evaporator 2-2, a turbine 2-3, a generator 2-4, a condenser 2-5, and a working fluid pump 2-6;

[0056] In one specific embodiment, the preheater 2-1 is heated by seawater. The inlet of the preheater 2-1 is connected to the outlet of the working fluid pump 2-6, and the outlet of the preheater 2-1 is connected to the inlet of the evaporator 2-2. The evaporator 2-2 is heated by geothermal water. The working fluid outlet of the evaporator 2-2 is connected to the turbine 2-3. The water-side outlet of the evaporator 2-2 is connected to the reinjection well 1-5 through the liquid collector 1-4. The turbine 2-3 is coaxially connected to the generator 2-4. The outlet of the turbine 2-3 is connected to the condenser 2-5, and the outlet of the condenser 2-5 is connected to the working fluid pump 2-6.

[0057] In some embodiments, the LNG vaporization and heating system includes an LNG storage tank 3-1, an LNG transfer pump 3-2, and an LNG vaporization device 3-3;

[0058] In one specific embodiment, the outlet of LNG storage tank 3-1 is connected to the outlet of condenser 2-5 via LNG transfer pump 3-2, and the LNG outlet of condenser 2-5 is connected to the inlet of LNG vaporization device 3-3; LNG vaporization device 3-3 is heated by seawater source heat pump or geothermal water in winter, and directly heated by seawater source in other seasons.

[0059] Specifically, such as Figure 1 As shown, the heating system specifically includes distributor 2 (4-1), valve 2 (4-2), collector 2 (4-3), circulating pump (4-4), distributor 3 (4-5), valve 3 (4-6), heat pump condenser (4-7), valve 4 (4-8), valve 5 (4-9), collector 3 (4-10), distributor 4 (4-11), throttle valve (4-12), heat pump evaporator (4-13), valve 6 (4-14), compressor (4-15), valve 7 (4-16), and collector 4 (4-17).

[0060] Example 2

[0061] refer to Figure 2This embodiment employs a single seawater heat source for heating. The difference from Embodiment 1 is that valve 1-3 needs to be closed, while one of the following connections remains open: distributor 1-2, distributor 4-11, collector 1-4, and collector 4-17. Based on this, this embodiment provides a coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity. The heating system is a seawater source heating system, which includes a seawater source heat pump heating system and a seawater source direct heating system. Specifically, the seawater source heating system includes distributor 2-1, collector 2-3, distributor 3-5, heat pump condenser 4-7, collector 3-10, evaporator 4-13, and compressor 4-15.

[0062] In one specific embodiment, the seawater source heat pump heating system includes a distributor 4-1; with valves 4-2 and 4-9 closed, seawater enters the distributor 4-1. One path of the distributor 4-1 is connected to the water-side inlet of the heat pump evaporator 4-13 via valve 4-14. The water-side outlet of the heat pump evaporator 4-13 is connected to the collector 4-10. The working fluid outlet of the evaporator 4-13 is connected to the compressor inlet 4-15. The outlet of the compressor 4-15 is connected to the heat pump condenser 4-7. The working fluid outlet of the condenser 4-7 is connected to the inlet of the evaporator 4-13 via a throttling valve 4-12. The circulating water outlet of the condenser 4-7 is connected to valve 4-8 and collector 4-3. The outlet of collector 4-3 is connected to the LNG vaporization unit 3-3. The outlet of the LNG vaporization unit 3-3 is connected to the circulating pump 4-4, which is then connected to the heat pump condenser 4-7 via distributor 4-5 and valve 4-6.

[0063] In one specific embodiment, the seawater source direct heating system includes a liquid collector 4-3; closed valves 4-6, 4-8, and 4-14; another path of the liquid distributor 4-1 is connected to the liquid collector 4-3 via valve 4-2; the outlet of the liquid collector 4-3 is connected to the LNG vaporization device 3-3; and the outlet of the LNG vaporization device 3-3 is connected to the liquid collector 4-10 via a circulating pump 4-4, the liquid distributor 4-5, and the valve 4-9.

[0064] Based on the geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system of this embodiment, a coupled power generation method based on the geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system is provided.

[0065] The specific workflow of the geothermal ORC power generation system includes:

[0066] The geothermal water from production well 1-1 is fed into the water side of evaporator 2-2, where it releases heat to the organic working fluid and is then reinjected through reinjection well 1-5. The organic working fluid absorbs heat and vaporizes into a saturated gaseous state in evaporator 2-2. The vaporized working fluid steam is then sent to turbine 2-3 for expansion and work to drive generator 2-4 to generate electricity. The exhaust steam at the outlet of turbine 2-3 is completely condensed into a liquid state in condenser and then pressurized to the evaporation pressure by working fluid pump 2-6. It is then sent to preheater 2-1 to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to evaporator to complete one ORC power generation cycle.

[0067] The workflow of an LNG vaporization and heating system includes:

[0068] The cryogenic LNG in LNG storage tank 3-1 is sent to condenser 2-5 (LNG preheater) via LNG transfer pump 3-2 to absorb the condensation heat of the power generation working fluid and complete the LNG preheating; the preheated LNG is sent to LNG vaporization unit 3-3 to absorb heat and vaporize, wherein the heat required for vaporization comes from the heating system.

[0069] The working process of a seawater source heat pump heating system in a heating system specifically includes:

[0070] In winter, when the seawater temperature is low, a seawater source heat pump is used for heating: valves 2-4-2 and 5-9 are closed, and valves 3-6, 4-8, and 6-14 are opened; the seawater source is sent into the heat pump evaporator 4-13 through the distributor 2-1 and valve 6-14, transferring heat to the heat pump working fluid and causing it to completely vaporize; the vaporized working fluid is pressurized to the condensing pressure by the compressor 4-15 and sent into the heat pump condenser 4-7, releasing heat to the circulating water, and then depressurized by the throttling valve 4-12 before finally flowing into the evaporator 4-13, completing one heat pump cycle; the circulating water absorbs heat and increases in temperature in the heat pump condenser 4-7, and then passes through valve 4-8 and the collector 2-3 before being sent into the LNG vaporization unit 3-3, transferring heat to the LNG, and then passes through the circulating pump 4-4, the distributor 3-5, and the valve 3-6 before being sent into the heat pump condenser 4-7, completing one water cycle;

[0071] The workflow of a direct seawater heating system within a heating system specifically includes:

[0072] In spring, summer, and autumn, when the seawater temperature is relatively high, direct heating is provided by seawater source: close valves 3-4-6, 4-8, and 6-14, and open valves 2-2 and 5-9; the seawater source is sent into the LNG vaporization unit 3-3 through separator 4-1, valve 2-2, and collector 2-3, directly transferring heat to the low-temperature LNG to vaporize it; the seawater after releasing heat is discharged through circulation pump 4-4, separator 3-5, valve 5-9, and collector 3-10.

[0073] Example 3

[0074] refer to Figure 3 This embodiment presents a hybrid heating scheme combining seawater and geothermal sources. The difference from Embodiment 1 is that this embodiment requires the throttle valve 4-12, valve six 4-14, and valve seven 4-16 to be closed, while one of the distributors 4-1, four 4-11, and three collectors 4-10 remains connected. Based on this, this embodiment provides a coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity, which includes a direct seawater heating system and a geothermal heating system. Specifically, the heating system includes collector two 4-3, distributor three 4-5, heat pump condenser 4-7, evaporator 4-13, compressor 4-15, and collector four 4-17.

[0075] In one specific embodiment, the geothermal heating system includes a heat pump condenser 4-7; valves 4-2 and 4-9 are closed; a distributor 1-2 is connected to the inlet of the heat pump condenser 4-7 via valve 1-3; the circulating water outlet of the heat pump condenser 4-7 is connected to the inlet of the collector 4-3 via valve 4-8; the outlet of the collector 4-3 is connected to the LNG vaporization device 3-3; the outlet of the LNG vaporization device 3-3 is connected to the circulating pump 4-4; and then connected to the heat pump condenser 4-7 via a distributor 4-5 and valve 4-6 to complete one water cycle.

[0076] In one specific embodiment, the seawater source direct heating system includes a liquid collector 2 4-3; closed valves 1-3, 4-6, and 4-8; the inlet side of the liquid collector 2 4-3 is connected to valve 2 4-2; the outlet of the liquid collector 2 4-3 is connected to the LNG vaporization device 3-3; the outlet of the vaporization device 3-3 is sequentially connected to the circulating pump 4-4, the distributor 3 4-5, and the valve 5 4-9; and seawater is fed into the LNG vaporization device 3-3 through valve 2 4-2 and the liquid collector 2 4-3.

[0077] Based on the geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system of this embodiment, a coupled power generation method based on the geothermal ORC-LNG cold energy-seawater source multi-energy complementary coupled power generation system is provided.

[0078] The specific workflow of the geothermal ORC power generation system includes:

[0079] The geothermal water from production well 1-1 is divided into two streams by separator 1-2. One stream is sent to the water side of evaporator 2-2, where it releases heat to the organic working fluid. After mixing with the other stream (which supplies heat to LNG vaporization unit 3-3) through collector 1-4, the mixture is reinjected through reinjection well 1-5. The organic working fluid absorbs heat and vaporizes to a saturated gaseous state in evaporator 2-2. The vaporized working fluid steam is then sent to turbine 2-3 for expansion, which drives generator 2-4 to generate electricity. The exhaust steam at the outlet of turbine 2-3 is completely condensed into a liquid state in condenser. It is then pressurized to the evaporation pressure by working fluid pump 2-6 and sent to preheater 2-1 to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to evaporator to complete one ORC power generation cycle.

[0080] The workflow of an LNG vaporization and heating system includes:

[0081] The cryogenic LNG in LNG storage tank 3-1 is sent to condenser 2-5 through LNG transfer pump 3-2 to absorb the condensation heat of the power generation working fluid and complete the LNG preheating; the preheated LNG is sent to LNG vaporization unit 3-3 to absorb heat and vaporize, and the heat required for vaporization comes from the heating system.

[0082] The workflow of a geothermal heating system within a heating system specifically includes:

[0083] In winter, when the seawater temperature is low, geothermal water is used for heating: valves 2-4-2 and 5-9 are closed, and valves 1-3, 3-6, and 4-8 are opened; the geothermal water is sent into the heat pump condenser 4-7, where it releases heat to the circulating water, and then mixes with another source in the collector 1-4 before being injected into the reinjection well 1-5; the circulating water absorbs heat and increases in temperature in the heat pump condenser 4-7, and then passes through valve 4-8 and collector 2-3 before being sent into the LNG vaporization unit 3-3, where it transfers heat to the LNG, and then passes through the circulating pump 4-4, distributor 3-5, and valve 3-6 before being sent back into the heat pump condenser 4-7, completing one water cycle;

[0084] The workflow of a direct seawater heating system within a heating system specifically includes:

[0085] In spring, summer, and autumn, when the seawater temperature is relatively high, direct heating is provided by seawater source: close valves 1-3, 4-6, and 4-8, and open valves 2-2 and 5-9; the seawater source is sent into the LNG vaporization unit 3-3 through valve 2-2 and collector 2-3, directly transferring heat to the low-temperature LNG and causing it to vaporize; the seawater after releasing heat is discharged from the heating system through circulating pump 4-4, distributor 3-5, and valve 5-9 in sequence.

[0086] Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity, characterized in that, This includes geothermal ORC power generation systems, LNG vaporization and heating systems, and heating systems. The geothermal ORC power generation system is connected to the LNG vaporization and heating system. The geothermal ORC power generation system provides a heat source for the LNG vaporization and heating system, and the LNG vaporization and heating system provides a cold source for the geothermal ORC power generation system. The geothermal ORC power generation system and the LNG vaporization and heating system are respectively connected to the heating system. The geothermal ORC power generation system includes a geothermal well group and a surface working fluid circulation system; the geothermal well group is connected to the surface working fluid circulation system. The geothermal well group includes a production well and a reinjection well; the outlet of the production well is connected to a liquid separator; the outlet of the liquid separator is divided into two paths, one of which is connected to the heat pump condenser in the heating system through a valve; the other path is connected to the water-side inlet of the evaporator in the surface working fluid circulation system; the two paths finally converge at a liquid collector and are connected to the reinjection well. The ground working fluid circulation system includes a preheater, evaporator, turbine, generator, condenser, and working fluid pump; The preheater uses seawater as its heating source. The preheater inlet is connected to the outlet of the working fluid pump, and the preheater outlet is connected to the evaporator inlet. The evaporator uses geothermal water as its heating source. The evaporator working fluid outlet is connected to the turbine, and the evaporator water-side outlet is connected to the reinjection well. The turbine is coaxially connected to the generator, the turbine outlet is connected to the condenser, and the condenser outlet is connected to the working fluid pump. The LNG vaporization and heating system includes an LNG storage tank, an LNG transfer pump, and an LNG vaporization device. The LNG storage tank outlet is connected to the condenser outlet via an LNG transfer pump, and the LNG outlet of the condenser is connected to the inlet of the LNG vaporization unit. The LNG vaporization unit is heated by a seawater source heat pump or geothermal water in winter, and by direct seawater source heating in other seasons. The heating system is a seawater source heating system, which includes a seawater source heat pump heating system and a seawater source direct heating system. The seawater source heat pump heating system includes a distributor II, through which seawater enters. Distributor II is connected to the water-side inlet of the heat pump evaporator via valve 6. The water-side outlet of the heat pump evaporator is connected to a collector III. The working fluid outlet of the heat pump evaporator is connected to the compressor inlet. The compressor outlet is connected to the heat pump condenser via valve 7 and collector IV. The working fluid outlet of the heat pump condenser is connected to the heat pump evaporator inlet via distributor IV and a throttling valve. The circulating water outlet of the heat pump condenser is connected to valve 4 and collector II. The outlet of collector II is connected to an LNG vaporization unit. The outlet of the LNG vaporization unit is connected to a circulating pump, which is then connected to the heat pump condenser via distributor III and valve III. The seawater source direct heating system includes a liquid collector two; another path of the liquid separator two is connected to the liquid collector two through a valve two, and the outlet of the liquid collector two is connected to the LNG vaporization device. The outlet of the LNG vaporization device is connected to the liquid collector three through a circulating pump, a liquid separator three, and a valve five in sequence.

2. A coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity, characterized in that, This includes geothermal ORC power generation systems, LNG vaporization and heating systems, and heating systems. The geothermal ORC power generation system is connected to the LNG vaporization and heating system. The geothermal ORC power generation system provides a heat source for the LNG vaporization and heating system, and the LNG vaporization and heating system provides a cold source for the geothermal ORC power generation system. The geothermal ORC power generation system and the LNG vaporization and heating system are respectively connected to the heating system. The geothermal ORC power generation system includes a geothermal well group and a surface working fluid circulation system; the geothermal well group is connected to the surface working fluid circulation system. The geothermal well group includes a production well and a reinjection well; the outlet of the production well is connected to a liquid separator; the outlet of the liquid separator is divided into two paths, one of which is connected to the heat pump condenser in the heating system through a valve; the other path is connected to the water-side inlet of the evaporator in the surface working fluid circulation system; the two paths finally converge at a liquid collector and are connected to the reinjection well. The ground working fluid circulation system includes a preheater, evaporator, turbine, generator, condenser, and working fluid pump; The preheater uses seawater as its heating source. The preheater inlet is connected to the outlet of the working fluid pump, and the preheater outlet is connected to the evaporator inlet. The evaporator uses geothermal water as its heating source. The evaporator working fluid outlet is connected to the turbine, and the evaporator water-side outlet is connected to the reinjection well. The turbine is coaxially connected to the generator, the turbine outlet is connected to the condenser, and the condenser outlet is connected to the working fluid pump. The LNG vaporization and heating system includes an LNG storage tank, an LNG transfer pump, and an LNG vaporization device. The LNG storage tank outlet is connected to the condenser outlet via an LNG transfer pump, and the LNG outlet of the condenser is connected to the inlet of the LNG vaporization unit. The LNG vaporization unit is heated by a seawater source heat pump or geothermal water in winter, and by direct seawater source heating in other seasons. The heating system includes a seawater source direct heating system and a geothermal water heating system; The geothermal heating system includes a heat pump condenser; a distributor is connected to the inlet of the heat pump condenser via a valve and a collector; the circulating water outlet of the heat pump condenser is connected to the inlet of the collector via a valve; the outlet of the collector is connected to the LNG vaporization device; the outlet of the LNG vaporization device is connected to the circulating pump; and the circulating water outlet is connected to the heat pump condenser via a distributor and a valve to complete one water cycle. The seawater source direct heating system includes a liquid collector 2, the inlet of which is connected to a valve 2, and the outlet of which is connected to an LNG vaporization device. The outlet of the vaporization device passes through a circulating pump, a distributor 3, and a valve 5 in sequence. Seawater is sent into the LNG vaporization device through valve 2 and liquid collector 2.

3. A coupled power generation method for a coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity as described in claim 1, characterized in that, The workflow of a geothermal ORC power generation system specifically includes: The geothermal water from the production well is fed into the water side of the evaporator, where it releases heat to the organic working fluid and is then reinjected through the reinjection well. The organic working fluid absorbs heat and vaporizes into a saturated gaseous state in the evaporator. The vaporized working fluid steam is then sent to the turbine for expansion to drive the generator and generate electricity. The exhaust steam at the turbine outlet is completely condensed into a liquid state in the condenser. It is then pressurized to the evaporation pressure by the working fluid pump and sent to the preheater to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to the evaporator to complete one ORC power generation cycle. The workflow of an LNG vaporization and heating system includes: The cryogenic LNG in the LNG storage tank is pumped into the condenser to absorb the condensation heat of the power generation working fluid, thus completing the LNG preheating. The preheated LNG is then sent into the LNG vaporization unit to absorb heat and vaporize, where the heat required for vaporization comes from the heating system.

4. The coupled power generation method of the coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity as described in claim 3, characterized in that, The working process of a seawater source heat pump heating system in a heating system specifically includes: Close valves 2 and 5, and open valves 3, 4, and 6. Seawater is fed into the heat pump evaporator through separator 2 and valve 6, transferring heat to the heat pump working fluid and causing it to completely vaporize. The vaporized working fluid is pressurized to condensing pressure by the compressor and sent into the heat pump condenser, releasing heat to the circulating water. It then passes through the throttling valve to reduce temperature and pressure, and finally flows into the heat pump evaporator, completing one heat pump cycle. The circulating water absorbs heat and increases in temperature in the heat pump condenser, then passes through valve 4 and collector 2 and is sent into the LNG vaporization unit, transferring heat to the LNG. It then passes through the circulating pump, separator 3, and valve 3 and is sent into the heat pump condenser, completing one water cycle. The workflow of a direct seawater heating system within a heating system specifically includes: Close valves 3, 4, and 6, and open valves 2 and 5; seawater is sent into the LNG vaporization unit through separator 2, valve 2, and collector 2, directly transferring heat to the cryogenic LNG to vaporize it; the seawater after releasing heat is discharged through the circulation pump, separator 3, valve 5, and collector 3.

5. A coupled power generation method for a coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity as described in claim 2, characterized in that, The workflow of a geothermal ORC power generation system specifically includes: The geothermal water from the production well is split into two streams by a distributor. One stream is sent to the water side of the evaporator, where it releases heat to the organic working fluid. After being mixed with the other stream through a collector, the mixture is reinjected through the reinjection well. The organic working fluid absorbs heat and vaporizes into a saturated gaseous state in the evaporator. The vaporized working fluid steam is then sent to the turbine for expansion, which drives the generator to generate electricity. The exhaust steam from the turbine outlet is completely condensed into a liquid state in the condenser. It is then pressurized to the evaporation pressure by the working fluid pump and sent to the preheater to absorb heat from the seawater source and heat it to a saturated liquid state. Finally, it is sent back to the evaporator to complete one ORC power generation cycle. The workflow of an LNG vaporization and heating system includes: The cryogenic LNG in the LNG storage tank is pumped into the condenser to absorb the condensation heat of the power generation working fluid, thus completing the LNG preheating. The preheated LNG is then sent into the LNG vaporization unit to absorb heat and vaporize, with the heat required for vaporization coming from the heating system.

6. The coupled power generation method of the coupled power generation system based on geothermal ORC-LNG cold energy-seawater source multi-energy complementarity as described in claim 5, characterized in that, The workflow of a geothermal heating system within a heating system specifically includes: Close valves 2, 5, and 7 and the throttle valve, and open valves 1, 3, and 4; geothermal water is sent into the heat pump condenser, releasing heat to the circulating water, and then mixed with another stream in collector 1 before being injected into the reinjection well; after absorbing heat and increasing temperature in the heat pump condenser, the circulating water passes through valve 4 and collector 2 in sequence and is then sent into the LNG vaporization unit to transfer heat to the LNG, and then passes through the circulating pump, distributor 3, and valve 3 back into the heat pump condenser to complete one water cycle; The workflow of a direct seawater heating system within a heating system specifically includes: Close valves 1, 3, 4, and 6, and open valves 2 and 5. Seawater is sent into the LNG vaporization unit through valve 2 and collector 2, directly transferring heat to the cryogenic LNG to vaporize it. The seawater that has released heat is discharged from the heating system through the circulation pump, distributor 3, and valve 5.

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