A low-temperature liquid carbon dioxide battery system applied to SOFC power generation

Abstract

The application discloses a low-temperature liquid carbon dioxide battery system applied to SOFC power generation, and relates to the technical field of carbon dioxide energy storage.The system comprises a solid oxide fuel cell-gas turbine module, which is used for making the solid oxide fuel cell perform an electrochemical reaction based on air, natural gas and water, generating electric energy, and discharging tail gas; a waste heat recovery module, which is connected with the solid oxide fuel cell-gas turbine module, is used for absorbing waste heat in the tail gas discharged by the solid oxide fuel cell-gas turbine module through two circulating loops and recovering electric energy; and a low-temperature liquid carbon dioxide battery module, which is connected with the waste heat recovery module, is used for storing electric energy and heat energy of the waste heat recovery module and supplying power for electric equipment.The application realizes the complementary advantages among the modules, thereby increasing the operation efficiency of the overall system, meeting the power consumption scene demand of medium and small scale peak load shifting, and realizing power supply stability in a region.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide energy storage technology, and in particular to a cryogenic liquid carbon dioxide battery system for power generation in a solid oxide fuel cell (SOFC). Background Technology

[0002] With the advancement of modern industrial civilization, environmental pollution and energy shortages have become significant obstacles to human future development. Currently, countries worldwide are actively engaged in technological reforms aimed at carbon reduction and zero-carbon transformation. The global energy structure is still based on fossil fuels such as coal and oil. To achieve zero-carbon goals, countries need to improve their energy structures and increase the proportion of renewable energy. However, renewable energy sources such as wind and solar power are characterized by intermittency in time and regionality in space. Therefore, large-scale renewable energy storage technologies urgently need development. Furthermore, centralized long-distance power supply from large power grids suffers from high transmission losses, low efficiency, and significant security risks. Distributed generation technology, however, can avoid these problems and will become a new trend in future development.

[0003] Among emerging energy sources, hydrogen energy, as a clean, efficient, and sustainable secondary energy source, can play a role in multiple fields, including transportation, industrial production, and power generation. Developing hydrogen energy can facilitate a smooth transition from traditional fossil fuels to renewable energy. Fuel cells, with their advantages of high efficiency, low emissions, and 24 / 7 operation, have become one of the most important new energy technologies of the 21st century. Among all fuel cells, solid oxide fuel cells (SOFCs) currently boast the highest conversion efficiency because they can effectively and sustainably convert the chemical energy in fuel and oxidant into electrical energy. SOFCs are also inexpensive and widely adaptable to various fuels, using common hydrocarbons such as methane, hydrogen, and natural gas as fuel. Furthermore, combining them with carbon capture, utilization, and storage (CCUS) technologies can achieve near-zero carbon emissions. These advantages mean that SOFCs will have a significant impact on future distributed power generation systems.

[0004] Distributed generation systems typically have a rated power of no more than 10MW. Therefore, when matching solid oxide fuel cell distributed micro-power stations, a small-to-medium scale, long-duration energy storage technology is required. Solid oxide fuel cell systems generate a constant power output, necessitating energy storage technology to flexibly allocate power according to load demand. Conventional electrochemical energy storage technologies, such as energy storage power stations, have short storage durations, high costs, and stringent system thermal management requirements, posing certain safety risks. While mechanical energy storage methods, such as compressed gas energy storage, offer safe operation, lower costs, and long-duration storage capabilities, their low energy density and large footprint make them less than ideal.

[0005] Therefore, there is a need for an energy storage system that can address the demand for flexible power allocation, peak shaving, and valley filling in distributed solid oxide fuel cell micropower stations. Summary of the Invention

[0006] The purpose of this invention is to provide a cryogenic liquid carbon dioxide battery system for SOFC power generation, which can flexibly adjust the power demand of peak shaving and valley filling scenarios to achieve stable power supply.

[0007] To achieve the above objectives, the present invention provides a cryogenic liquid carbon dioxide battery system for SOFC power generation, comprising:

[0008] Solid oxide fuel cell-gas turbine module, used to enable solid oxide fuel cells to carry out electrochemical reactions based on air, natural gas and water, generate electrical energy and exhaust gas;

[0009] The waste heat recovery module is connected to the solid oxide fuel cell-gas turbine module and is used to absorb the waste heat in the exhaust gas discharged from the solid oxide fuel cell-gas turbine module through two circulation loops and recover electrical energy.

[0010] A cryogenic liquid carbon dioxide battery module is connected to the waste heat recovery module to store the electrical and thermal energy of the waste heat recovery module and to supply power to electrical equipment.

[0011] Optionally, the solid oxide fuel cell-gas turbine module includes: an air compressor, a natural gas compressor, a first pump body, a preheating device, a reformer, a fuel cell stack, a combustion chamber, and a gas turbine;

[0012] The air compressor is connected to the cathode inlet of the fuel cell stack via the preheating device; the natural gas compressor and the first pump body are both connected to the inlet of the reformer via the preheating device; the outlet of the reformer is connected to the anode inlet of the fuel cell stack; the anode outlet and the cathode outlet of the fuel cell stack are both connected to the inlet of the combustion chamber; the outlet of the combustion chamber is connected to the inlet of the gas turbine; the outlet of the gas turbine is connected to the preheating device; the preheating device is also connected to the waste heat recovery module.

[0013] The air compressor is used to pressurize the air and then pass the pressurized air into the preheating device for heating, thereby providing cathode gas for the fuel cell stack.

[0014] The natural gas compressor is used to pressurize natural gas and then pass the pressurized natural gas into the preheating device for heating; the first pump body is used to pressurize water and then pass the pressurized water into the preheating device for heating; the reformer is used to perform a reforming reaction on the heated natural gas and heated water to provide anode gas for the fuel cell stack;

[0015] The internal structure of the fuel cell stack undergoes an electrochemical reaction under the action of the cathode gas and the anode gas to generate electrical energy, and the gas is discharged through the anode outlet and the cathode outlet; the gas discharged from the fuel cell stack is burned in the combustion chamber and then enters the gas turbine to expand and do work to generate electrical energy; the exhaust gas at the outlet of the gas turbine is introduced into the preheating device; the preheating device discharges the exhaust gas.

[0016] Optionally, the preheating device includes: a first preheater, a second preheater, and a third preheater; the first preheater is located between the air compressor and the cathode inlet of the fuel cell stack; the second preheater is located between the natural gas compressor and the reformer; the third preheater is located between the first pump body and the reformer; the first preheater, the second preheater, and the third preheater are all connected to the waste heat recovery module; the outlet of the gas turbine is connected to the heat exchange chambers of the first preheater, the second preheater, and the third preheater, respectively.

[0017] Optionally, the waste heat recovery module includes: an evaporator, a first expander, a second expander, a first regenerator, a second regenerator, a multiphase flow heat exchanger, a carbon dioxide storage tank, and a second pump body;

[0018] The outlet of the carbon dioxide storage tank, the second pump body, a heat exchange chamber of the first regenerator, a heat exchange chamber of the evaporator, the first expander, a heat exchange chamber of the second regenerator, a heat exchange chamber of the multiphase flow heat exchanger, and the inlet of the carbon dioxide storage tank are connected in sequence to form a first circulation loop.

[0019] The outlet of the carbon dioxide storage tank, the second pump body, another heat exchange chamber of the second regenerator, the second expander, another heat exchange chamber of the first regenerator, a heat exchange chamber of the multiphase flow heat exchanger, and the inlet of the carbon dioxide storage tank are connected in sequence to form a second circulation loop.

[0020] The multiphase flow heat exchanger is also connected to the cryogenic liquid carbon dioxide battery module;

[0021] The carbon dioxide flowing out of the carbon dioxide storage tank enters the second pump body, is pressurized, and is divided into two streams of carbon dioxide fluid. The first stream of carbon dioxide fluid enters a heat exchange chamber of the first regenerator, is heated, and then enters a heat exchange chamber of the evaporator. After absorbing heat from the exhaust gas discharged from the solid oxide fuel cell-gas turbine module, it is fed into the first expander to expand and generate electricity. After that, it is fed into a heat exchange chamber of the second regenerator to release heat and cool down. Then, it enters a heat exchange chamber of the multiphase flow heat exchanger for further cooling and finally enters the carbon dioxide storage tank.

[0022] The second stream of carbon dioxide fluid enters another heat exchange chamber of the second regenerator, absorbs heat and heats up, then enters the second expander to expand and generate electricity. After that, it enters another heat exchange chamber of the first regenerator to release heat and cool down, then enters a heat exchange chamber of the multiphase flow heat exchanger for further cooling, and finally enters the carbon dioxide storage tank.

[0023] Optionally, the cryogenic liquid carbon dioxide battery module includes: a first liquid carbon dioxide storage tank, a second liquid carbon dioxide storage tank, an expansion valve, a third pump body, a first heat exchanger, a second heat exchanger, a third heat exchanger, a cryogenic turbine, a gas-liquid separator, an energy storage device, an energy release device, a cooling device, a heating device, a radiator, a methanol cold storage device, and a first turbine.

[0024] The outlet of the first liquid carbon dioxide storage tank, the expansion valve, a heat exchange chamber of the first heat exchanger, the waste heat recovery module, the energy storage device, the cooling device, the methanol cold storage device, the cryogenic turbine, and the inlet of the gas-liquid separator are connected in sequence; the gas outlet of the gas-liquid separator is connected to the waste heat recovery module, and the liquid outlet of the gas-liquid separator is connected to the inlet of the second liquid carbon dioxide storage tank.

[0025] The outlet of the second liquid carbon dioxide storage tank, the third pump body, a heat exchange chamber of the second heat exchanger, the heating device, the energy release device, the radiator, a heat exchange chamber of the third heat exchanger, the first turbine, a heat exchange chamber of the first heat exchanger, and the inlet of the first liquid carbon dioxide storage tank are connected in sequence.

[0026] Carbon dioxide flowing from the outlet of the first liquid carbon dioxide storage tank enters the expansion valve, where it is depressurized and heated. It then enters a heat exchange chamber of the first heat exchanger to absorb heat and reach a saturated gaseous state. It flows into the waste heat recovery module to absorb heat, then enters the energy storage device for pressurization, consuming electrical energy. Next, it enters the cooling device for cooling, then enters the methanol cold storage device to absorb cold energy from methanol and cool down. Finally, it enters the cryogenic turbine for expansion and depressurization, generating a gas-liquid mixture of carbon dioxide that flows into the gas-liquid separator. Gaseous carbon dioxide enters the waste heat recovery module from the gas outlet of the gas-liquid separator for energy storage circulation. Liquid carbon dioxide enters the second liquid carbon dioxide storage tank from the liquid outlet of the gas-liquid separator for storage.

[0027] The carbon dioxide flowing out of the second liquid carbon dioxide storage tank enters the third pump body for pressurization and is divided into two streams. The first stream of carbon dioxide enters a heat exchange chamber of the second heat exchanger for heating, and the second stream of carbon dioxide enters the third heat exchanger for heating. After heating, the two streams of carbon dioxide merge and enter the heating device for further heating. Then, they enter the energy release device to generate electrical energy, enter the radiator for cooling, and then flow into a heat exchange chamber of the third heat exchanger for further cooling. After cooling, they pass through the first turbine and enter a heat exchange chamber of the first heat exchanger to absorb the cold energy carried by the internal phase change material and become liquid carbon dioxide. Finally, they flow into the first liquid carbon dioxide storage tank for storage.

[0028] Optionally, the energy storage device is also connected to the solid oxide fuel cell-gas turbine module to store the electrical energy generated by the solid oxide fuel cell-gas turbine module.

[0029] Optionally, the energy storage device includes a first compressor and a second compressor; the cooling device includes a first intercooler and a second intercooler; the inlet of the first compressor is connected to the waste heat recovery module, and the outlet of the first compressor is connected to the inlet of the first intercooler; the outlet of the first intercooler is connected to the inlet of the second compressor; the outlet of the second compressor is connected to the inlet of the second intercooler; and the outlet of the second intercooler is connected to the methanol cold storage device.

[0030] Optionally, the heating device includes a fourth preheater and a fifth preheater; the energy release device includes a second turbine and a third turbine; the inlet of the fourth preheater is connected to a heat exchange chamber of the second heat exchanger and a heat exchange chamber of the third heat exchanger, respectively; the outlet of the fourth preheater is connected to the inlet of the second turbine; the outlet of the second turbine is connected to the inlet of the fifth preheater; the outlet of the fifth preheater is connected to the inlet of the third turbine; and the outlet of the third turbine is connected to the radiator.

[0031] Optionally, the methanol storage and cooling device includes: a fourth heat exchanger, a methanol hot storage tank, and a methanol cold storage tank; the inlet of the fourth heat exchanger is connected to the cooling device and the outlet of the methanol hot storage tank respectively; the outlet of the fourth heat exchanger is connected to the cryogenic turbine and the inlet of the methanol cold storage tank respectively; the outlet of the methanol cold storage tank and the inlet of the methanol hot storage tank are both connected to the second heat exchanger.

[0032] Optionally, the cryogenic liquid carbon dioxide battery module further includes a heat storage device; the heat storage device is connected to both the cooling device and the heating device.

[0033] According to specific embodiments provided by the present invention, the following technical effects are disclosed: A micropower station based on a distributed solid oxide fuel cell-gas turbine coupled waste heat recovery module establishes a liquid carbon dioxide battery. The waste heat from the carbon dioxide in the waste heat recovery module provides sufficient heat for the cryogenic liquid carbon dioxide battery module, achieving complementary advantages between the modules and thus increasing overall operating efficiency. By storing the electrical and thermal energy of the solid oxide fuel cell-gas turbine module and the waste heat recovery module through the cryogenic liquid carbon dioxide battery module, the power demand of small- to medium-scale "peak shaving and valley filling" scenarios can be met, achieving stable power supply within the region. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a cryogenic liquid carbon dioxide battery system for SOFC power generation provided by the present invention.

[0036] Symbol Explanation: 1. Air compressor; 2. Natural gas compressor; 3. First pump body; 4. First preheater; 5. Second preheater; 6. Third preheater; 7. Reformer; 8. Fuel cell stack; 9. Combustion chamber; 10. Gas turbine; 11. First generator; 12. Carbon dioxide storage tank; 13. Second pump body; 14. First regenerator; 15. Second regenerator; 16. Second expander; 17. Third generator; 18. Evaporator; 19. First expander; 20. Second generator; 21. Multiphase flow heat exchanger; 22. First liquid carbon dioxide storage tank; 23. Expansion valve; 24. First heat exchanger; 25. First compressor; 26. Second compressor; 27. Fourth heat exchanger; 28. Cryogenic turbine; 29. ​​Fourth generator; 30. Gas-liquid separator; 31. Second liquid carbon dioxide storage tank; 32. Third pump body; 33. Second heat exchanger; 34. Third heat exchanger; 35. Second turbine; 36. Fifth generator; 37. Third turbine; 38. Sixth generator; 39. Radiator; 40. First turbine; 41. Seventh generator; 42. Cryogenic heat storage tank; 43. First intercooler; 44. Second intercooler; 45. High-temperature heat storage tank; 46. Fourth preheater; 47. Fifth preheater; 48. Methanol hot storage tank; 49. Methanol cold storage tank. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The purpose of this invention is to solve the long-standing problem of power mismatch in terms of time and location faced by distributed micro-power stations in the prior art, and to provide a cryogenic liquid carbon dioxide battery system for SOFC power generation, which uses cryogenic liquid carbon dioxide batteries to flexibly output power to users in conjunction with distributed solid oxide fuel cell micro-power stations.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] The cryogenic liquid carbon dioxide battery system for SOFC power generation provided by this invention includes: a solid oxide fuel cell-gas turbine module, a waste heat recovery module, and a cryogenic liquid carbon dioxide battery module.

[0041] Solid oxide fuel cell-gas turbine modules are used to generate electricity from the electrochemical reactions of air, natural gas, and water in solid oxide fuel cells, while producing exhaust gases. In other words, the solid oxide fuel cell-gas turbine module utilizes the chemical energy of methane, water, and air to convert into electrical energy, producing high-temperature exhaust gases.

[0042] The waste heat recovery module is connected to the solid oxide fuel cell-gas turbine module. The waste heat recovery module absorbs the waste heat from the exhaust gas discharged from the solid oxide fuel cell-gas turbine module through two circulation loops and recovers electrical energy. By absorbing the waste heat from the high-temperature exhaust gas, the waste heat recovery module improves the efficiency of the transcritical carbon dioxide power generation cycle, further enhancing energy utilization.

[0043] The cryogenic liquid carbon dioxide battery module is connected to the waste heat recovery module. The cryogenic liquid carbon dioxide battery module is used to store the electrical and thermal energy of the waste heat recovery module and to supply power to the electrical equipment.

[0044] The following is combined Figure 1 The structure and connection relationship of the three modules are described in detail.

[0045] (1) The solid oxide fuel cell-gas turbine module includes: an air compressor 1, a natural gas compressor 2, a first pump body 3, a preheating device, a reformer 7, a fuel cell stack 8, a combustion chamber 9, and a gas turbine 10.

[0046] The air compressor 1 is connected to the cathode inlet of the fuel cell stack 8 via the preheating device. The natural gas compressor 2 and the first pump body 3 are both connected to the inlet of the reformer 7 via the preheating device. The outlet of the reformer 7 is connected to the anode inlet of the fuel cell stack 8. The anode outlet and cathode outlet of the fuel cell stack 8 are both connected to the inlet of the combustion chamber 9. The outlet of the combustion chamber 9 is connected to the inlet of the gas turbine 10. The outlet of the gas turbine 10 is connected to the preheating device. The gas turbine 10 is also connected to the first generator 11. The preheating device is also connected to the waste heat recovery module.

[0047] The preheating device includes a first preheater 4, a second preheater 5, and a third preheater 6. The first preheater 4 is located between the air compressor 1 and the cathode inlet of the fuel cell stack 8. The second preheater 5 is located between the natural gas compressor 2 and the reformer 7. The third preheater 6 is located between the first pump body 3 and the reformer 7. The first preheater 4, the second preheater 5, and the third preheater 6 are all connected to the waste heat recovery module. The outlet of the gas turbine 10 is connected to the heat exchange chambers of the first preheater 4, the second preheater 5, and the third preheater 6, respectively.

[0048] The air compressor 1 is used to pressurize the air and then pass the pressurized air into the preheating device for heating, thereby providing cathode gas for the fuel cell stack 8.

[0049] The natural gas compressor 2 is used to pressurize natural gas and then pass the pressurized natural gas into the preheating device for heating. The first pump body 3 is used to pressurize water and then pass the pressurized water into the preheating device for heating. The reformer 7 is used to perform a reforming reaction on the heated natural gas and heated water to provide anode gas for the fuel cell stack 8.

[0050] The fuel cell stack 8 generates electricity through an electrochemical reaction under the action of the cathode and anode gases, and the electricity is discharged through the anode and cathode outlets. The discharged gas from the fuel cell stack 8 is burned in the combustion chamber 9 and then enters the gas turbine 10 to expand and generate electricity. The high-temperature, high-pressure exhaust gas drives the turbine of the gas turbine 10 to recover some of the electrical energy. The exhaust gas at the outlet of the gas turbine 10 is fed into the preheating device. The preheating device then discharges the exhaust gas.

[0051] Specifically, air is pressurized by air compressor 1 and then heated in a heat exchange chamber of the first preheater 4. It is then fed into the cathode of fuel cell stack 8 to provide cathode gas for the electrochemical reaction. Natural gas is pressurized by natural gas compressor 2 and then heated in a heat exchange chamber of the second preheater 5. Water is pressurized by water in the first pump body 3 and then heated in a heat exchange chamber of the third heat exchanger 34. The heated water and heated natural gas enter the reforming chamber for a reforming reaction. The outlet of the reforming chamber is connected to the anode of fuel cell stack 8 to provide anode gas for the electrochemical reaction. Electrochemical reactions occur inside fuel cell stack 8 to generate electricity. The gas flow from the anode and cathode outlets of fuel cell stack 8 enters combustion chamber 9, forming high-temperature, high-pressure gas. The high-temperature, high-pressure gas from combustion chamber 9 enters gas turbine 10, expands, and performs work to further generate electricity. The high-temperature, low-pressure exhaust gas from gas turbine 10 is divided into three streams and enters heat exchange chambers of the first preheater 4, second preheater 5, and third preheater 6 respectively to heat the working fluid, ensuring the smooth progress of the chemical reaction. The chemical energy in the working fluid is successfully converted into electrical energy.

[0052] (2) The waste heat recovery module includes: evaporator 18, first expander 19, second expander 16, first regenerator 14, second regenerator 15, multiphase flow heat exchanger 21, carbon dioxide storage tank 12 and second pump body 13.

[0053] The outlet of the carbon dioxide storage tank 12, the second pump body 13, a heat exchange chamber of the first regenerator 14, a heat exchange chamber of the evaporator 18, the first expander 19, a heat exchange chamber of the second regenerator 15, a heat exchange chamber of the multiphase flow heat exchanger 21, and the inlet of the carbon dioxide storage tank 12 are connected in sequence to form a first circulation loop.

[0054] The outlet of the carbon dioxide storage tank 12, the second pump body 13, another heat exchange chamber of the second regenerator 15, the second expander 16, another heat exchange chamber of the first regenerator 14, a heat exchange chamber of the multiphase flow heat exchanger 21, and the inlet of the carbon dioxide storage tank 12 are connected in sequence to form a second circulation loop.

[0055] The first expander 19 is also connected to the second generator 20, and the second expander 16 is also connected to the third generator 17.

[0056] The waste heat from the high-temperature exhaust gas is further absorbed through two circulation loops, and some electrical energy is recovered.

[0057] The multiphase flow heat exchanger 21 is also connected to the cryogenic liquid carbon dioxide battery module.

[0058] The carbon dioxide flowing out of the carbon dioxide storage tank 12 enters the second pump body 13 and is pressurized, then split into two carbon dioxide fluids. The first carbon dioxide fluid enters a heat exchange chamber of the first regenerator 14 and is heated. Then it enters a heat exchange chamber of the evaporator 18, absorbs heat from the exhaust gas discharged from the solid oxide fuel cell-gas turbine module, and is then fed into the first expander 19 to expand and generate electricity. After that, it is fed into a heat exchange chamber of the second regenerator 15 to release heat and cool down. Finally, it enters a heat exchange chamber of the multiphase flow heat exchanger 21 for further cooling and then enters the carbon dioxide storage tank 12.

[0059] After the second stream of carbon dioxide fluid enters another heat exchange chamber of the second regenerator 15 to absorb heat and rise in temperature, it is fed into the second expander 16 to expand and generate electricity. Then, it is fed into another heat exchange chamber of the first regenerator 14 to release heat and cool down. After entering a heat exchange chamber of the multiphase flow heat exchanger 21 for cooling down, it enters the carbon dioxide storage tank 12.

[0060] The two cooled carbon dioxide fluids merge and enter a heat exchange chamber of the multiphase flow heat exchanger 21 for further cooling by cooling water.

[0061] (3) The cryogenic liquid carbon dioxide battery module includes: a first liquid carbon dioxide storage tank 22, a second liquid carbon dioxide storage tank 31, an expansion valve 23, a third pump body 32, a first heat exchanger 24, a second heat exchanger 33, a third heat exchanger 34, a cryogenic turbine 28, a gas-liquid separator 30, an energy storage device, an energy release device, a cooling device, a heating device, a radiator 39, a methanol storage and cooling device, and a first turbine 40.

[0062] The outlet of the first liquid carbon dioxide storage tank 22, the expansion valve 23, a heat exchange chamber of the first heat exchanger 24, a heat exchange chamber of the multiphase flow heat exchanger 21 in the waste heat recovery module, the energy storage device, the cooling device, the methanol cold storage device, the cryogenic turbine 28, and the inlet of the gas-liquid separator 30 are connected in sequence. The cryogenic turbine 28 is also connected to a fourth generator 29. The gas outlet of the gas-liquid separator 30 is connected to a heat exchange chamber of the multiphase flow heat exchanger 21 in the waste heat recovery module, and the liquid outlet of the gas-liquid separator 30 is connected to the inlet of the second liquid carbon dioxide storage tank 31.

[0063] The outlet of the second liquid carbon dioxide storage tank 31, the third pump body 32, a heat exchange chamber of the second heat exchanger 33, the heating device, the energy release device, the radiator 39, a heat exchange chamber of the third heat exchanger 34, the first turbine 40, a heat exchange chamber of the first heat exchanger 24, and the inlet of the first liquid carbon dioxide storage tank 22 are connected in sequence. The first turbine 40 is also connected to the seventh generator 41.

[0064] The second heat exchanger 33 and the third heat exchanger 34 are connected in parallel and placed between the outlet of the third pump body 32 and the heating device.

[0065] The energy storage device is also connected to the solid oxide fuel cell-gas turbine module to store the electrical energy generated by the solid oxide fuel cell-gas turbine module.

[0066] The energy storage device includes a first compressor 25 and a second compressor 26. The cooling device includes a first intercooler 43 and a second intercooler 44. The inlet of the first compressor 25 is connected to the waste heat recovery module, and the outlet of the first compressor 25 is connected to the inlet of the first intercooler 43. The outlet of the first intercooler 43 is connected to the inlet of the second compressor 26. The outlet of the second compressor 26 is connected to the inlet of the second intercooler 44. The outlet of the second intercooler 44 is connected to the methanol cold storage device.

[0067] The heating device includes a fourth preheater 46 and a fifth preheater 47. The energy release device includes a second turbine 35 and a third turbine 37. The inlet of the fourth preheater 46 is connected to a heat exchange chamber of the second heat exchanger 33 and a heat exchange chamber of the third heat exchanger 34, respectively. The outlet of the fourth preheater 46 is connected to the inlet of the second turbine 35. The outlet of the second turbine 35 is connected to the inlet of the fifth preheater 47. The outlet of the fifth preheater 47 is connected to the inlet of the third turbine 37. The outlet of the third turbine 37 is connected to the radiator 39. The second turbine 35 is also connected to a fifth generator 36, and the third turbine 37 is also connected to a sixth generator 38. The second turbine 35 and the third turbine 37 are also connected to electrical equipment to provide electrical energy to the equipment.

[0068] The energy release device is used to electrically connect to the user's electrical equipment to supply power to the user's electrical equipment.

[0069] The methanol storage and cooling device includes a fourth heat exchanger 27, a methanol hot storage tank 48, and a methanol cold storage tank 49. The inlet of the fourth heat exchanger 27 is connected to both the cooling device and the outlet of the methanol hot storage tank 48. The outlet of the fourth heat exchanger 27 is connected to both the cryogenic turbine 28 and the inlet of the methanol cold storage tank 49. The outlet of the methanol cold storage tank 49 and the inlet of the methanol hot storage tank 48 are both connected to the second heat exchanger 33.

[0070] That is, the outlet of the methanol hot storage tank 48, a heat exchange chamber of the fourth heat exchanger 27, the inlet of the methanol cold storage tank 49, a heat exchange chamber of the second heat exchanger 33, and the inlet of the methanol hot storage tank 48 are connected in sequence.

[0071] The cryogenic liquid carbon dioxide battery module also includes a heat storage device. The heat storage device is connected to both the cooling device and the heating device. The heat storage device includes a high-temperature heat storage tank 45 and a low-temperature heat storage tank 42. The inlet of the high-temperature heat storage tank 45 is connected to the first intercooler 43 and the second intercooler 44, respectively, and the outlet of the high-temperature heat storage tank 45 is connected to the fourth preheater 46 and the fifth preheater 47, respectively. The inlet of the low-temperature heat storage tank 42 is connected to the fourth preheater 46 and the fifth preheater 47, respectively, and the outlet of the low-temperature heat storage tank 42 is connected to the first intercooler 43 and the second intercooler 44, respectively.

[0072] The cooling device is located between the heat storage device and the energy storage device to reduce the outlet temperature of the first compressor 25 and the second compressor 26, thereby reducing power loss.

[0073] The heating device is located between the heat storage device and the energy release device, and is used to increase the inlet temperature of the second turbine 35 and the third turbine 37 to increase the output power.

[0074] Carbon dioxide flowing from the outlet of the first liquid carbon dioxide storage tank 22 enters the expansion valve 23, where it is depressurized and heated. It then enters a heat exchange chamber of the first heat exchanger 24 to absorb heat and reach a saturated gaseous state. It flows into another heat exchange chamber of the multiphase flow heat exchanger 21 in the waste heat recovery module to absorb heat. Afterward, it enters the first compressor 25 of the energy storage device for pressurization, consuming electrical energy. It then enters the first intercooler 43 of the cooling device for cooling, and then enters the second compressor 26 of the energy storage device for pressurization. It then enters the second intercooler 44 of the cooling device for cooling, and then enters a heat exchange chamber of the fourth heat exchanger 27 in the methanol cold storage device to absorb cold energy from methanol and cool down. Finally, it enters the cryogenic turbine 28 for expansion and depressurization, generating a gas-liquid mixture of carbon dioxide that flows into the gas-liquid separator 30. Gaseous carbon dioxide enters a heat exchange chamber of the multiphase flow heat exchanger 21 in the waste heat recovery module from the gas outlet of the gas-liquid separator 30 for energy storage circulation. Liquid carbon dioxide enters the second liquid carbon dioxide storage tank 31 from the liquid outlet of the gas-liquid separator 30 for storage.

[0075] The carbon dioxide flowing out of the outlet of the second liquid carbon dioxide storage tank 31 enters the third pump body 32 for pressurization and is divided into two streams. The first stream of carbon dioxide enters a heat exchange chamber of the second heat exchanger 33 for heating, and the second stream of carbon dioxide enters the third heat exchanger 34 for heating. After heating, the two streams of carbon dioxide merge and enter the fourth preheater 46 of the heating device for further heating. Then, they enter the second turbine 35 of the energy release device to expand and drive the generator to generate electricity. They then enter the fifth preheater 47 of the heating device for further heating, and then enter the third turbine 37 of the energy release device to expand and drive the generator to generate electricity. They then enter the radiator 39 for cooling, and then flow into a heat exchange chamber of the third heat exchanger 34 for cooling. After cooling, they pass through the first turbine 40 and enter a heat exchange chamber of the first heat exchanger 24 to absorb the cold energy carried by the internal phase change material and become liquid carbon dioxide. Finally, they flow into the first liquid carbon dioxide storage tank 22 for storage.

[0076] In this process, carbon dioxide is further depressurized by an expansion device before entering the first turbine 40, in preparation for liquefaction.

[0077] The cryogenic liquid carbon dioxide battery module absorbs heat from the waste heat recovery module through a multiphase flow heat exchanger 21 to heat the carbon dioxide and increase its energy storage power. During energy storage, excess electrical energy drives the compressor to store it as heat energy. During discharge, the high-temperature, high-pressure carbon dioxide drives the turbine to generate electricity.

[0078] On the one hand, the present invention can store the electrical and thermal energy of the solid oxide fuel cell-gas turbine module and the waste heat recovery module through the cryogenic liquid carbon dioxide battery module, which can meet the power demand of small and medium-sized "peak shaving and valley filling" scenarios and achieve stable power supply in a region. On the other hand, the liquefaction cycle in the cryogenic liquid carbon dioxide battery module enables the carbon dioxide working fluid to be stored in liquid form in the storage tank, which reduces the footprint of the energy storage system and achieves a significant increase in energy storage density, which is a major technological advancement compared to compressed air energy storage.

[0079] In the solid oxide fuel cell-gas turbine module power generation process, natural gas, air, and water are pressurized and enter the fuel cell stack to undergo electrochemical reactions to generate electricity. The exhaust gas, after combustion in combustion chamber 9, carries extremely high heat energy, which is further converted into electricity by the gas turbine 10. However, the high-temperature exhaust gas still carries a significant amount of usable heat energy after passing through three preheaters. The waste heat recovery module can utilize this heat energy, allowing high-pressure carbon dioxide to absorb heat before entering the two-stage expander, then expanding to drive the generator to output electricity. Once started, the solid oxide fuel cell-gas turbine module and waste heat recovery module can generate electricity continuously. Generally, a secondary energy storage battery is needed to store and utilize this energy. This allows for flexible adjustment of the output power to meet peak and off-peak electricity demands from users. However, large-scale energy storage power stations pose significant safety risks, are costly, and have short lifespans, making them unsuitable as energy storage methods for distributed power stations. Mechanical energy storage is a safer, more reliable, and less expensive option. This invention establishes a liquid carbon dioxide battery in a micro power station based on a distributed solid oxide fuel cell-gas turbine coupled waste heat recovery module. The waste heat from the carbon dioxide in the waste heat recovery module provides sufficient heat for the energy storage system, achieving complementary advantages between modules and thus increasing the overall operating efficiency.

[0080] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A cryogenic liquid carbon dioxide battery system for SOFC power generation, characterized in that, The cryogenic liquid carbon dioxide battery system used in SOFC power generation includes: Solid oxide fuel cell-gas turbine module, used to enable solid oxide fuel cells to carry out electrochemical reactions based on air, natural gas and water, generate electrical energy and exhaust gas; The waste heat recovery module is connected to the solid oxide fuel cell-gas turbine module and is used to absorb the waste heat in the exhaust gas discharged from the solid oxide fuel cell-gas turbine module through two circulation loops and recover electrical energy. A cryogenic liquid carbon dioxide battery module is connected to the waste heat recovery module to store the electrical and thermal energy of the waste heat recovery module and to supply power to the electrical equipment. The waste heat recovery module includes: an evaporator, a first expander, a second expander, a first regenerator, a second regenerator, a multiphase flow heat exchanger, a carbon dioxide storage tank, and a second pump body; The outlet of the carbon dioxide storage tank, the second pump body, a heat exchange chamber of the first regenerator, a heat exchange chamber of the evaporator, the first expander, a heat exchange chamber of the second regenerator, a heat exchange chamber of the multiphase flow heat exchanger, and the inlet of the carbon dioxide storage tank are connected in sequence to form a first circulation loop. The outlet of the carbon dioxide storage tank, the second pump body, another heat exchange chamber of the second regenerator, the second expander, another heat exchange chamber of the first regenerator, a heat exchange chamber of the multiphase flow heat exchanger, and the inlet of the carbon dioxide storage tank are connected in sequence to form a second circulation loop. The multiphase flow heat exchanger is also connected to the cryogenic liquid carbon dioxide battery module; The carbon dioxide flowing out of the carbon dioxide storage tank enters the second pump body, is pressurized, and is divided into two streams of carbon dioxide fluid. The first stream of carbon dioxide fluid enters a heat exchange chamber of the first regenerator, is heated, and then enters a heat exchange chamber of the evaporator. After absorbing heat from the exhaust gas discharged from the solid oxide fuel cell-gas turbine module, it is fed into the first expander to expand and generate electricity. After that, it is fed into a heat exchange chamber of the second regenerator to release heat and cool down. Then, it enters a heat exchange chamber of the multiphase flow heat exchanger for further cooling and finally enters the carbon dioxide storage tank. The second stream of carbon dioxide fluid enters another heat exchange chamber of the second regenerator, absorbs heat and heats up, then enters the second expander to expand and generate electricity. After that, it enters another heat exchange chamber of the first regenerator to release heat and cool down, then enters a heat exchange chamber of the multiphase flow heat exchanger for further cooling, and finally enters the carbon dioxide storage tank.

2. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 1, characterized in that, The solid oxide fuel cell-gas turbine module includes: an air compressor, a natural gas compressor, a first pump body, a preheating device, a reformer, a fuel cell stack, a combustion chamber, and a gas turbine; The air compressor is connected to the cathode inlet of the fuel cell stack via the preheating device; the natural gas compressor and the first pump body are both connected to the inlet of the reformer via the preheating device; the outlet of the reformer is connected to the anode inlet of the fuel cell stack; the anode outlet and the cathode outlet of the fuel cell stack are both connected to the inlet of the combustion chamber; the outlet of the combustion chamber is connected to the inlet of the gas turbine; the outlet of the gas turbine is connected to the preheating device; the preheating device is also connected to the waste heat recovery module. The air compressor is used to pressurize the air and then pass the pressurized air into the preheating device for heating, thereby providing cathode gas for the fuel cell stack. The natural gas compressor is used to pressurize natural gas and then pass the pressurized natural gas into the preheating device for heating; the first pump body is used to pressurize water and then pass the pressurized water into the preheating device for heating; the reformer is used to perform a reforming reaction on the heated natural gas and heated water to provide anode gas for the fuel cell stack; The internal structure of the fuel cell stack undergoes an electrochemical reaction under the action of the cathode gas and the anode gas to generate electrical energy, and the gas is discharged through the anode outlet and the cathode outlet; the gas discharged from the fuel cell stack is burned in the combustion chamber and then enters the gas turbine to expand and do work to generate electrical energy; the exhaust gas at the outlet of the gas turbine is introduced into the preheating device; the preheating device discharges the exhaust gas.

3. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 2, characterized in that, The preheating device includes: a first preheater, a second preheater, and a third preheater; The first preheater is located between the air compressor and the cathode inlet of the fuel cell stack; the second preheater is located between the natural gas compressor and the reformer; the third preheater is located between the first pump body and the reformer; the first preheater, the second preheater and the third preheater are all connected to the waste heat recovery module; The outlet of the gas turbine is connected to the heat exchange chambers of the first preheater, the second preheater, and the third preheater, respectively.

4. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 1, characterized in that, The cryogenic liquid carbon dioxide battery module includes: a first liquid carbon dioxide storage tank, a second liquid carbon dioxide storage tank, an expansion valve, a third pump body, a first heat exchanger, a second heat exchanger, a third heat exchanger, a cryogenic turbine, a gas-liquid separator, an energy storage device, an energy release device, a cooling device, a heating device, a radiator, a methanol cold storage device, and a first turbine. The outlet of the first liquid carbon dioxide storage tank, the expansion valve, a heat exchange chamber of the first heat exchanger, the waste heat recovery module, the energy storage device, the cooling device, the methanol cold storage device, the cryogenic turbine, and the inlet of the gas-liquid separator are connected in sequence; the gas outlet of the gas-liquid separator is connected to the waste heat recovery module, and the liquid outlet of the gas-liquid separator is connected to the inlet of the second liquid carbon dioxide storage tank. The outlet of the second liquid carbon dioxide storage tank, the third pump body, a heat exchange chamber of the second heat exchanger, the heating device, the energy release device, the radiator, a heat exchange chamber of the third heat exchanger, the first turbine, a heat exchange chamber of the first heat exchanger, and the inlet of the first liquid carbon dioxide storage tank are connected in sequence. Carbon dioxide flowing from the outlet of the first liquid carbon dioxide storage tank enters the expansion valve, where it is depressurized and heated. It then enters a heat exchange chamber of the first heat exchanger to absorb heat and reach a saturated gaseous state. It flows into the waste heat recovery module to absorb heat, then enters the energy storage device for pressurization, consuming electrical energy. Next, it enters the cooling device for cooling, then enters the methanol cold storage device to absorb cold energy from methanol and cool down. Finally, it enters the cryogenic turbine for expansion and depressurization, generating a gas-liquid mixture of carbon dioxide that flows into the gas-liquid separator. Gaseous carbon dioxide enters the waste heat recovery module from the gas outlet of the gas-liquid separator for energy storage circulation. Liquid carbon dioxide enters the second liquid carbon dioxide storage tank from the liquid outlet of the gas-liquid separator for storage. The carbon dioxide flowing out of the second liquid carbon dioxide storage tank enters the third pump body for pressurization and is divided into two streams. The first stream of carbon dioxide enters a heat exchange chamber of the second heat exchanger for heating, and the second stream of carbon dioxide enters the third heat exchanger for heating. After heating, the two streams of carbon dioxide merge and enter the heating device for further heating. Then, they enter the energy release device to generate electrical energy, enter the radiator for cooling, and then flow into a heat exchange chamber of the third heat exchanger for further cooling. After cooling, they pass through the first turbine and enter a heat exchange chamber of the first heat exchanger to absorb the cold energy carried by the internal phase change material and become liquid carbon dioxide. Finally, they flow into the first liquid carbon dioxide storage tank for storage.

5. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 4, characterized in that, The energy storage device is also connected to the solid oxide fuel cell-gas turbine module to store the electrical energy generated by the solid oxide fuel cell-gas turbine module.

6. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 4, characterized in that, The energy storage device includes a first compressor and a second compressor; the cooling device includes a first intercooler and a second intercooler; The inlet of the first compressor is connected to the waste heat recovery module, and the outlet of the first compressor is connected to the inlet of the first intercooler; the outlet of the first intercooler is connected to the inlet of the second compressor; the outlet of the second compressor is connected to the inlet of the second intercooler; and the outlet of the second intercooler is connected to the methanol storage and cooling device.

7. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 4, characterized in that, The heating device includes a fourth preheater and a fifth preheater; the energy release device includes a second turbine and a third turbine; The inlet of the fourth preheater is connected to a heat exchange chamber of the second heat exchanger and a heat exchange chamber of the third heat exchanger, respectively. The outlet of the fourth preheater is connected to the inlet of the second turbine. The outlet of the second turbine is connected to the inlet of the fifth preheater. The outlet of the fifth preheater is connected to the inlet of the third turbine. The outlet of the third turbine is connected to the radiator.

8. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 4, characterized in that, The methanol storage and cooling device includes: a fourth heat exchanger, a methanol hot storage tank, and a methanol cold storage tank. The inlet of the fourth heat exchanger is connected to the outlet of the cooling device and the methanol hot storage tank, respectively; the outlet of the fourth heat exchanger is connected to the inlet of the cryogenic turbine and the methanol cold storage tank, respectively; the outlet of the methanol cold storage tank and the inlet of the methanol hot storage tank are both connected to the second heat exchanger.

9. The cryogenic liquid carbon dioxide battery system for SOFC power generation according to claim 4, characterized in that, The cryogenic liquid carbon dioxide battery module also includes a heat storage device; the heat storage device is connected to both the cooling device and the heating device.

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