A method for operating a liquid air energy storage system coupled thermoelectrically to a thermal power unit

Abstract

The application discloses a kind of liquid air energy storage systems of thermal power generating unit thermal coupling operation method, based on and the original fire power generating system connection of thermal power generating unit liquid air energy storage system, wherein, liquid air energy storage system includes air compression liquefaction subsystem, liquid air expansion power generation system and cold and hot circulation subsystem, cold and hot circulation subsystem includes high-temperature compression heat storage module, low-temperature compression heat coupling regenerative system module, cold storage module and industrial steam high-temperature heat storage module;The method includes the following scene under the operation method: A. coupling thermal power generating unit deep peak shaving operation method;B. joint thermal power generating unit peak operation method;C1. joint thermal power generating unit deep peak shaving operation method under heating condition;C2. joint thermal power generating unit peak operation method under heating condition.The application solves the problem that the present thermal power generating unit is coupled with liquid air energy storage and is complex, and the original operation mode of thermal power generating unit is greatly influenced, and the efficiency of liquid air energy storage system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage and thermal power generation, in particular to a method for operating a liquid air energy storage system coupled with a thermal power unit. BACKGROUND

[0002] In recent years, the proportion of new energy such as wind power and photovoltaic in China's energy structure has rapidly increased, and by 2025, the proportion of non-fossil energy consumption will reach about 20%. Due to the intermittent nature of new energy power generation, in order to ensure the safe grid connection of new energy and improve the comprehensive regulation capacity of the power system, the state has greatly increased the requirements for the number of times and quality of coal-fired units participating in peak shaving. As an important flexible peak shaving power source, thermal power units have changed from power guaranteeing in the past to power and quantity guaranteeing. One of the main tasks at present is to implement flexible modification of the largest proportion of existing installed thermal power units to improve the deep peak shaving capacity and operational flexibility of the units.

[0003] Configuring energy storage is one of the important means to improve the flexibility of thermal power units. Liquid air energy storage is a long-term energy storage technology with flexible thermal and electrical output characteristics during operation, and there is no geographical condition restriction for site selection, which perfectly fits the current "three modification linkage" of thermal power units and is one of the optimal choices for thermal power plants to configure energy storage. At present, most of the research on the coupling of thermal power units and liquid air energy storage or compressed air energy storage technology is through the use of high-pressure steam of thermal power units to drive compressors. However, from the actual operation of thermal power units, the implementation of this technology inevitably requires modification of high-temperature and high-pressure steam pipelines (main steam pipeline, reheat steam pipeline, high-pressure cylinder exhaust pipeline, and feedwater pipeline) of thermal power units, which involves a wide range of unit modification and is difficult to implement. In addition, there is little research on the operation method of the coupling of thermal power units and liquid air energy storage technology, which limits the coupling application of liquid air energy storage technology and thermal power units. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for operating a liquid air energy storage system coupled with a thermal power unit to solve the problems of complex modification of the coupling of thermal power units and liquid air energy storage and great influence on the original operation mode of thermal power units, and effectively improve the efficiency of the liquid air energy storage system.

[0005] To solve the above technical problems, the technical solutions adopted by the present application are as follows.

[0006] A method for operating a liquid air energy storage system coupled with a thermal power unit, based on a liquid air energy storage system connected with a thermal power generation system of the thermal power unit and used for normal production of electric energy, industrial steam and civil heating, wherein the liquid air energy storage system comprises an air compression and liquefaction subsystem for accommodating electric load of the thermal power unit and converting electric energy into liquid air for storage during energy storage, a liquid air expansion power generation subsystem for generating power by using liquid air to expand and do work during energy release and putting the generated power on the grid together with the power generated by the thermal power unit, and a cold and heat circulation subsystem for realizing efficient storage and utilization of cold and heat during energy storage and energy release, the cold and heat circulation subsystem comprising a high-temperature compression heat storage module, a low-temperature compression heat coupled heat recovery system module, a cold storage module and an industrial steam high-temperature heat storage module; the method comprises the following operating methods in different scenarios:

[0007] A. Deep peak shaving operation method coupled with a thermal power unit

[0008] When the thermal power unit needs to be deeply peak shaved, the electric load of the unit itself cannot meet the requirements of the power grid or the peak shaving auxiliary service subsidy is considerable, and the peak shaving instruction of the power grid is assumed to be P w , at this time the thermal power generation system is normally operated, the minimum electric load that can be reached is P g , P g >P w , the electric energy generated by the thermal power unit is accommodated by the liquid air energy storage system to reduce the on-grid power of the thermal power unit, the liquid air energy storage system stores energy, the air compression and liquefaction subsystem operates, the high-temperature compression heat storage module in the cold and heat circulation subsystem stores high-temperature compression heat, the low-temperature compression heat coupled heat recovery system module operates, the cold storage module releases cold, and the liquid air expansion power generation subsystem does not operate, the auxiliary electric load is P c , then the electric load P x accommodated by the liquid air energy storage system is P g -P w -P c .

[0009] B. Peak shaving operation method combined with a thermal power unit

[0010] When the thermal power unit needs to be peak shaved or the output of the unit is limited due to other reasons and encounters peak shaving of the power grid, the peak shaving instruction of the power grid is assumed to be P w , at this time the highest electric load that can be reached by the thermal power generation system is P g , P w >P g, the liquid air energy storage system is discharged, and the liquid air expansion power generation system is started and runs, the high-temperature compression heat storage module in the cold and heat circulation subsystem is discharged, the cold storage module is stored cold, the industrial steam high-temperature heat storage module is discharged, the air compression liquefaction subsystem and the low-temperature compression heat coupling regenerative system module do not run, and the auxiliary power load is P c , the liquid air expansion power generation system in the liquid air energy storage system needs to generate an electric load P k = P w -P g -P c ;

[0011] C1. Deep peak shaving operation method of combined thermal power generating unit in heating condition

[0012] In the heating condition, the external network heating capacity is Q w , the thermal power generating unit cannot meet the deep peak shaving requirement of the power grid due to heating, assuming that the power grid instruction is P w , at this time, the thermal power generating unit runs at the lowest electric load P w that can be reached under the heating capacity Q g , P g >P w , the electric energy generated by the liquid air energy storage system is absorbed to reduce the on-grid electric capacity of the thermal power generating unit, the liquid air energy storage system is stored, and the operation method and the electric load to be absorbed are consistent with those in method A.

[0013] C2. Peak shaving operation method of combined thermal power generating unit in heating condition

[0014] In the heating condition, the external network heating capacity is Q w , the thermal power generating unit cannot meet the peak shaving requirement of the power grid due to heating, assuming that the power grid instruction is P w , at this time, the thermal power generating unit runs at the highest electric load P w that can be reached under the heating capacity Q g , P g <P w , the electric energy generated by the combined liquid air energy storage system is increased to increase the on-grid electric capacity of the thermal power generating unit, at this time, the thermal power generating unit normally runs, the liquid air energy storage system is discharged, and the operation method and the electric load of the liquid air expansion power generation system are consistent with those in method B.

[0015] Preferably, the air compression and liquefaction subsystem comprises a first compressor for compressing air and a second compressor connected in series with the first compressor, a first compressor after-cooler is arranged between the first compressor and the second compressor for cooling the exhaust gas of the first compressor, an after-cooler of the second compressor is arranged behind the second compressor for cooling the exhaust gas of the second compressor, and a liquefaction main heat exchanger is arranged behind the after-cooler of the second compressor for cooling the air coming out of the after-cooler of the second compressor; a low-temperature throttle valve, a gas-liquid separator and a liquid air storage tank are arranged in sequence behind the liquefaction main heat exchanger, so that the air cooled by the liquefaction main heat exchanger is stored in the liquid air storage tank in the form of normal-pressure liquid after passing through the low-temperature throttle valve and the gas-liquid separator; the first compressor is connected with a first compressor motor, the second compressor is connected with a second compressor motor, and the total power consumption of the first compressor motor and the second compressor motor is P x .

[0016] Preferably, the liquid air expansion power generation subsystem comprises a low-temperature liquid pump, an evaporator, an air-water heater, an air-salt heater, an air expander, an air-salt reheater, an air expansion generator and an energy storage system transformer arranged in sequence behind the liquid air storage tank, so that the liquid air in the liquid air storage tank is pressurized by the low-temperature liquid pump, enters the evaporator to become high-pressure normal-temperature air, is heated by the air-water heater and the air-salt heater in sequence, enters the air expander to do work to drive the air expansion generator to generate power; the power generation load of the air expansion generator is P k The power supply of the first compressor motor and the second compressor motor is connected from the energy storage system transformer, and the high-voltage side of the energy storage system transformer is also connected with the outlet of the steam turbine generator or the bus in the thermal power generation subsystem, so that the air compression and liquefaction system can absorb the power generated by the steam turbine generator in the thermal power generation subsystem during the energy storage process, and the air expansion generator can generate power and be connected with the power generated by the steam turbine generator in the thermal power generation subsystem to be put on the grid during the energy release process.

[0017] Preferably, the high-temperature compression heat storage module is used for storing high-temperature compression heat in the air compression liquefaction subsystem and using the high-temperature compression heat for power generation in the liquid air expansion power generation subsystem and heat supply in the thermal power subsystem, and the high-temperature compression heat storage module comprises a normal-temperature water tank for storing normal-temperature water and a high-temperature hot water tank for storing high-temperature water from the first compressor after-cooler; the water inlet of the high-temperature hot water tank is connected with the hot water outlet of the first compressor after-cooler, and the water outlet of the high-temperature hot water tank is connected with the hot water inlet of the air-water heater, so that the high-temperature water in the high-temperature hot water tank is used to primarily heat air in the process of power generation in the liquid air expansion power generation subsystem through the air-water heater; the water inlet of the normal-temperature water tank is connected with the cold water outlet of the air-water heater, and the water outlet of the normal-temperature water tank is connected with the cold water inlet of the first compressor after-cooler; the water outlet of the high-temperature hot water tank is also connected with the hot water inlet of the heat supply heat exchanger in the thermal power subsystem through a pipeline and a heat supply heat exchanger inlet valve arranged on the pipeline, so that the high-temperature water in the high-temperature hot water tank is used to jointly and commonly supply heat to the outside with the heat network heater in the thermal power subsystem through the heat supply heat exchanger; the cold water outlet of the heat supply heat exchanger is also connected with the water inlet of the normal-temperature water tank through a pipeline and a heat supply heat exchanger outlet valve arranged on the pipeline.

[0018] Preferably, the low-temperature compression heat coupling regenerative system module is used for directly using low-temperature compression heat in the air compression liquefaction subsystem for a regenerative unit in the thermal power subsystem and simultaneously introducing condensate water in the thermal power subsystem as cooling working medium of the air compression liquefaction subsystem; the low-temperature compression heat coupling regenerative system module realizes connection of the shaft seal heater water outlet in the regenerative unit and the cold water inlet of the second compressor after-cooler through a pipeline and realizes connection of the hot water outlet of the second compressor after-cooler and the inlet of the fifth low-pressure heater and the inlet of the sixth low-pressure heater in the regenerative unit through a pipeline and a valve; the low-temperature compression heat coupling regenerative system module selects to introduce the warmed condensate water in the second compressor after-cooler into the inlet of the fifth low-pressure heater or the inlet of the sixth low-pressure heater according to different loads of the thermal power subsystem.

[0019] Preferably, the cold storage module is used for storing cold energy released when liquid air changes from liquid state to gaseous state in the evaporator in the process of operation of the liquid air expansion power generation subsystem and transferring the part of cold energy to the main liquefaction heat exchanger in the process of operation of the air compression liquefaction subsystem; the cold storage module comprises a packed bed for storing cold energy, the packed bed is connected in parallel between the evaporator and the main liquefaction heat exchanger through a pipeline, and the inlet and the outlet of the packed bed are correspondingly provided with a packed bed inlet control valve and a packed bed outlet control valve for realizing adjustment of the cold storage and cold release processes.

[0020] Preferably, the industrial steam high-temperature heat storage module is used to store high-quality sensible heat in industrial extraction steam of a thermal power generation system and generate electricity in a liquid air expansion power generation system; the industrial steam high-temperature heat storage module comprises a steam-salt heat exchanger connected in parallel with a water injection desuperheater in the thermal power generation system and used to cool the reheat extraction steam to a user demand temperature and supply the steam to a heat user, and a steam-salt heat exchanger inlet valve and a steam-salt heat exchanger outlet valve arranged one-to-one at a steam inlet and a steam outlet of the steam-salt heat exchanger; a low-temperature molten salt tank is connected to a molten salt inlet of the steam-salt heat exchanger, and a heat storage molten salt pump is arranged between the low-temperature molten salt tank and the steam-salt heat exchanger and used to pump low-temperature molten salt in the low-temperature molten salt tank into the steam-salt heat exchanger; a high-temperature molten salt tank is connected to a molten salt outlet of the steam-salt heat exchanger, and a heat-releasing molten salt pump is connected to a bottom outlet of the high-temperature molten salt tank and connected to molten salt inlets of an air-salt heater and an air-salt reheater respectively and used to pump high-temperature molten salt in the high-temperature molten salt tank into the air-salt heater and the air-salt reheater, and molten salt outlets of the air-salt heater and the air-salt reheater are connected to a top inlet of the low-temperature molten salt tank, so that the high-temperature molten salt in the high-temperature molten salt tank enters the low-temperature molten salt tank after heating air in the process of electricity generation of the liquid air expansion power generation system through the air-salt heater and the air-salt reheater.

[0021] Preferably, the method comprises the following operation methods in the following scenarios:

[0022] D. Heat and electricity shortage combined heat and power operation method of thermal power generating unit in extremely cold weather

[0023] In extremely cold weather, the external network is short of heat and electricity, and the thermal power generating unit is operated at the maximum heat supply condition, and the electric load is P w , and the corresponding maximum heat supply is Q max , at this time, the electric load instruction of the power grid is P w , P g <P w , the heat load demand of the heat network is Q w , Q w >Q max , then the corresponding electric load gap is ΔP=P w -P g , and the heat load gap is ΔQ=Q w -Q max, the power generated by the combined liquid air energy storage system is increased to increase the power of the power plant on the grid, and the surplus compression heat of the high-temperature compression heat storage module is used for heating, at this time, the liquid air expansion power generation system operates, the high-temperature compression heat storage module in the cold-heat circulation subsystem releases heat, the industrial steam high-temperature heat storage module releases heat, the water inlet valve and the water outlet valve of the heating heat exchanger are opened, and the heating heat exchanger works, part of the hot water from the high-temperature hot water tank goes to the air-water heater to heat the air, and part of the hot water goes to the heating heat exchanger to jointly heat the heat network heater to supply heat to the outside, and the power generation load of the air expansion generator in the liquid air energy storage system is ΔP=P w -P g , the high-temperature compression heat storage module in the cold-heat circulation subsystem releases heat to the outside except for preheating the air-inlet of the air-salt heater, and the heat released for external heating is ΔQ=Q max -Q w .

[0024] Preferably, the operation method of the industrial steam high-temperature heat storage module is as follows:

[0025] The heat storage process of the industrial steam high-temperature heat storage module is independent of the energy storage and release processes of the liquid air energy storage system, and can be operated as long as the thermal power generation system normally operates to supply industrial steam to the outside, the heat storage duration of the industrial steam high-temperature heat storage module mainly depends on the demand of the heat user, and the heat release process of the industrial steam high-temperature heat storage module is mainly accompanied by the release process of the liquid air energy storage system, and the heat storage duration M c of the industrial steam high-temperature heat storage module is calculated as follows:

[0026] Suppose the demand of the external industrial user for industrial steam is D1, t / h, and the demand parameter is P1, T1, the corresponding enthalpy value H1, kJ / kg, is calculated according to the demand parameter, the parameter of the reheated steam of the thermal power generation system is P c , T c , the corresponding enthalpy value is H c , kJ / kg, and accordingly, the heat storage power of the industrial steam high-temperature heat storage module per hour HG c =D1× / 3.6, kW; according to the inlet and outlet parameters of the air-expander, the air-salt heater and the air-salt reheater, the demand power of the high-temperature heat in the release process of the liquid air energy storage system can be known, which is HG f , and the release duration of the liquid air energy storage system is M b ;

[0027] According to the above parameters, the heat storage process operation duration M c of the industrial steam high-temperature heat storage module is HG f ×M b / HG cIn other time periods, the industrial steam high-temperature heat storage module does not store heat, and the industrial steam supply is switched to the original water spray desuperheating mode.

[0028] Thanks to the above technical solutions, the present application has the following technical progress.

[0029] The present application utilizes the liquid air energy storage system to absorb the power generated by the thermal power unit in the energy storage process, reduces the on-grid power of the thermal power unit, and jointly regulates the peak of the thermal power unit; in the process of peak demand of the thermal power unit, the liquid air energy storage system releases energy to jointly peak the thermal power unit, improving the flexibility of the thermal power unit operation. By using the compression heat with low temperature in the compression process to heat the condensate water of the thermal power unit, and using the compression heat with high temperature to heat the air in the energy release process, the compression heat is reasonably utilized, and the existing industrial steam extraction of the thermal power unit is used to add an industrial steam high-temperature heat storage module to replace the original water spray desuperheating, so as to store the high-quality heat in the industrial steam extraction and use it to heat the air at the inlet of the expander in the energy release process of the liquid air energy storage system, which not only recovers the high-quality energy, but also improves the energy utilization efficiency of the liquid air energy storage system.

[0030] The coupling of the thermal power unit and the liquid air energy storage system is scientific, reasonable and easy to implement, the high-quality energy of the thermal power unit is reasonably utilized, the original system of the thermal power unit is less modified, the coupling between heat and electricity is realized, and the mode of joint operation of the thermal power unit and the liquid air energy storage system is flexible. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a system structure schematic diagram of the present application.

[0032] Wherein: 1. First compressor, 2. First compressor motor, 3. Second compressor, 4. Second compressor motor, 5. First compressor after-cooler, 6. Normal temperature water tank, 7. High temperature hot water tank, 8. Second compressor after-cooler, 9. Main liquefied heat exchanger, 10. Cryogenic throttle valve, 11. Packed bed, 12. Packed bed inlet control valve, 13. Packed bed outlet control valve, 14. Gas-liquid separator, 15. Liquid air storage tank, 16. Cryogenic liquid pump, 17. Evaporator, 18. Air-water heater, 19. Air-molten salt heater, 20. Air-molten salt reheater, 21. High temperature molten salt tank, 22. Exothermic molten salt pump, 23. Molten salt exothermic bypass valve, 24. Cryogenic molten salt tank, 25. Heat storage molten salt pump, 26. Molten salt heat storage bypass valve, 27. Air expander, 28. Air expansion generator, 29. Steam-molten salt heat exchanger inlet valve, 30. Steam-molten salt heat exchanger, 31. Steam-molten salt heat exchanger outlet valve, 32. Water spray desuperheater, 33. Deaerator, 34. Feed water pump, 35. No. 3 high pressure heater, 36. No. 2 high pressure heater, 37. No. 1 high pressure heater, 38. Boiler, 39. Turbine high pressure cylinder, 40. Turbine intermediate pressure cylinder, 41. Turbine low pressure cylinder, 42. Turbine generator, 43. Energy storage system transformer, 44. Condenser, 45. Shaft seal heater, 46. No. 8 low pressure heater, 47. No. 7 low pressure heater, 48. No. 6 low pressure heater, 49. No. 5 low pressure heater, 50. Heat supply heat exchanger outlet valve, 51. Heat supply heat exchanger inlet valve, 52. Heat supply heat exchanger, 53. Heat network heater. DETAILED DESCRIPTION

[0033] The application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] A method for operating a liquid air energy storage system coupled with a thermal power generating unit, based on a liquid air energy storage system, combined with a thermal power generating unit, comprising the steps of: Figure 1As shown, the liquid air energy storage system includes an air compression liquefaction subsystem, a liquid air expansion power generation system, and a thermal cycle subsystem. All three subsystems are connected to the existing thermal power generation system of the thermal power unit. The thermal power generation system is used for normal power generation, industrial steam, and residential heating. The air compression liquefaction subsystem absorbs the electrical load of the thermal power unit during energy storage, converting electrical energy into liquid air for storage. This reduces the unit's grid connection power by absorbing the electrical energy generated by the thermal power generation system, thus supporting deep peak shaving for the thermal power unit. The liquid air expansion power generation system generates electricity by increasing the pressure and temperature of liquid air during energy release, sharing the power generated by the thermal power unit with the grid connection power, thus supporting peak operation of the thermal power unit. The thermal cycle subsystem is used to achieve efficient storage and utilization of cold and heat during energy storage and release.

[0035] The thermal power generation system is existing technology, including a water spray desuperheater 32, a deaerator 33, a feedwater pump 34, a No. 3 high-pressure heater 35, a No. 2 high-pressure heater 36, a No. 1 high-pressure heater 37, a boiler 38, a steam turbine high-pressure cylinder 39, a steam turbine intermediate-pressure cylinder 40, a steam turbine low-pressure cylinder 41, a steam turbine generator 42, a condenser 44, a shaft seal heater 45, a No. 8 low-pressure heater 46, a No. 7 low-pressure heater 47, a No. 6 low-pressure heater 48, a No. 5 low-pressure heater 49, a heating heat exchanger 52, and a heating network heater 53. The connection relationships of each component are as follows: Figure 1 As shown, and will not be repeated here, the shaft seal heater 45, the No. 8 low-pressure heater 46, the No. 7 low-pressure heater 47, the No. 6 low-pressure heater 48, and the No. 5 low-pressure heater 49 are connected in sequence to form the reheat unit in the thermal power generation system; the water spray desuperheater 32 is used to cool the reheated steam to the user's required temperature before supplying it to the heat user; the steam turbine generator 42 is used to generate electricity.

[0036] The air compression and liquefaction subsystem comprises a first compressor 1 and a second compressor 3 connected in series for compressing air, wherein the first compressor 1 is connected with a first compressor motor 2, and the second compressor 3 is connected with a second compressor motor 4. A first compressor after-cooler 5 is arranged between the first compressor 1 and the second compressor 3, and is used for cooling the exhaust gas of the first compressor 1. A second compressor after-cooler 8 is arranged behind the second compressor 3, and is used for cooling the exhaust gas of the second compressor 3. A liquefaction main heat exchanger 9 is arranged behind the second compressor after-cooler 8, and is used for cooling the air from the second compressor after-cooler 8. A low-temperature throttling valve 10, an air-liquid separator 14 and a liquid air storage tank 15 are arranged in sequence behind the liquefaction main heat exchanger 9, so that the air cooled by the liquefaction main heat exchanger 9 is stored in the liquid air storage tank 15 in the form of normal-pressure liquid through the low-temperature throttling valve 10 and the air-liquid separator 14.

[0037] The number of compressors of the air compression and liquefaction subsystem includes but is not limited to the first compressor 1 and the second compressor 3, and the exhaust gas temperature of each compressor is determined according to specific process parameters. In this embodiment, the exhaust gas temperature of the first compressor 1 is higher than that of the second compressor 3, and the number and connection mode of the compressors are not limited to the mode mentioned in this embodiment.

[0038] The liquid air expansion power generation subsystem comprises a low-temperature liquid pump 16, an evaporator 17, an air-water heater 18, an air-salt heater 19, an air expander 27, an air-salt reheater 20, an air expansion generator 28 and an energy storage system transformer 43 connected in sequence behind the liquid air storage tank 15, so that the liquid air in the liquid air storage tank 15 is pressurized by the low-temperature liquid pump 16, enters the evaporator 17, becomes high-pressure normal-temperature air, is heated by the air-water heater 18 and the air-salt heater 19 in sequence, enters the air expander 27 to do work, and the air expander 27 drives the air expansion generator 28 to generate electricity. The electric energy consumed by the first compressor motor 2 and the second compressor motor 4 comes from the electric energy generated in the thermal power generation subsystem, and the power supply of the first compressor motor 2 and the second compressor motor 4 is connected from the energy storage system transformer 43. The high-voltage side of the energy storage system transformer 43 is also connected with the outlet of the steam turbine generator 42 or the bus in the thermal power generation subsystem, so that the air compression and liquefaction in the energy storage process absorbs the electric energy generated by the steam turbine generator in the thermal power generation subsystem, and the electric energy generated by the air expansion generator 28 in the energy release process is combined into the energy storage system transformer 43, and is connected with the electric energy generated by the steam turbine generator 42 in the thermal power generation subsystem to be put on the grid.

[0039] The cold and heat cycle subsystem comprises a high-temperature compressed heat storage module, a low-temperature compressed heat coupling regenerative system module, a cold storage module and an industrial steam high-temperature heat storage module.

[0040] The high-temperature compressed heat storage module is used for storing high-temperature compressed heat in the air compression liquefaction subsystem and supplying the high-temperature compressed heat to the liquid air expansion power generation subsystem for power generation and to the thermal power subsystem for heat supply, the high-temperature compressed heat being higher-temperature exhaust gas in the first compressor 1 and the second compressor 3. Specifically, the high-temperature compressed heat storage module comprises a normal-temperature water tank 6 and a high-temperature hot water tank 7, wherein the normal-temperature water tank 6 is used for storing normal-temperature water, and the high-temperature hot water tank 7 is used for storing high-temperature water from the first compressor after-cooler 5. The water inlet of the high-temperature hot water tank 7 is connected with the hot water outlet of the first compressor after-cooler 5, and the water outlet of the high-temperature hot water tank 7 is connected with the hot water inlet of the air-water heater 18; the water inlet of the normal-temperature water tank 6 is connected with the cold water outlet of the air-water heater 18, and the water outlet of the normal-temperature water tank 6 is connected with the cold water inlet of the first compressor after-cooler 5. In the air compression liquefaction process, the cooling water from the normal-temperature water tank 6 enters the first compressor after-cooler 5 to cool the exhaust gas of the first compressor 1, and the cooling water with increased temperature is stored in the high-temperature hot water tank 7, and the stored hot water is used for primary heating of air in the liquid air expansion power generation process by the air-water heater 18.

[0041] The water outlet of the high-temperature hot water tank 7 is also connected with the hot water inlet of a heat supply heat exchanger 52 in the thermal power subsystem through a pipeline and a heat supply heat exchanger inlet valve 51 arranged on the pipeline, so that the high-temperature water in the high-temperature hot water tank 7 is used for external heat supply together with a heat network heater 53 in the thermal power subsystem through the heat supply heat exchanger 52; and the cold water outlet of the heat supply heat exchanger 52 is also connected with the water inlet of the normal-temperature water tank 6 through a pipeline and a heat supply heat exchanger outlet valve 50 arranged on the pipeline, so that the cooled water is returned to the normal-temperature water tank 6.

[0042] The low-temperature compression heat coupling regenerative system module is used for directly using the low-temperature compression heat in the air compression liquefaction subsystem in the regenerative unit in the thermal power generation subsystem, and simultaneously introducing the condensate water in the thermal power generation subsystem as the cooling working medium of the air compression liquefaction subsystem. The low-temperature compression heat is the lower-temperature exhaust gas in the first compressor 1 and the second compressor 3. Specifically, the low-temperature compression heat coupling regenerative system module is connected with the water outlet of the shaft seal heater 45 in the regenerative unit and the cold water inlet of the second compressor post-cooler 8 through a pipeline. The low-temperature compression heat coupling regenerative system module is also connected with the hot water outlet of the second compressor post-cooler 8 and the inlets of the No. 5 low-pressure heater 49 and the No. 6 low-pressure heater 48 in the regenerative unit through a pipeline and a valve, so as to directly use the low-temperature compression heat in the air compression liquefaction subsystem in the regenerative unit in the thermal power generation subsystem, and simultaneously introduce the condensate water in the thermal power generation subsystem as the cooling working medium of the air compression liquefaction subsystem. The low-temperature compression heat coupling regenerative system module selects the condensate water in the second compressor post-cooler 8 after being heated to be introduced into the inlet of the No. 5 low-pressure heater 49 or the inlet of the No. 6 low-pressure heater 48 according to the different loads of the thermal power generation subsystem.

[0043] The cold storage module is used for storing the cold energy released when the liquid air changes from liquid state to gaseous state in the evaporator 17 in the operation process of the liquid air expansion power generation system, and transferring the part of the cold energy to the liquefaction main heat exchanger 9 in the operation process of the air compression liquefaction subsystem. Specifically, the cold storage module includes a packed bed 11 used for storing the cold energy. The packed bed 11 is connected in parallel between the evaporator 17 and the liquefaction main heat exchanger 9 through a pipeline. The cold energy released when the air changes from liquid state to gaseous state in the evaporator 17 is stored by the packed bed 11. The cold energy stored by the packed bed 11 is used for the liquefaction main heat exchanger 9. Meanwhile, the cold energy of the liquefaction main heat exchanger 9 also comes from the cold energy provided by the low-temperature gas returned from the gas-liquid separator 14. The packed bed inlet control valve 12 and the packed bed outlet control valve 13 are arranged in one-to-one correspondence at the top inlet and the bottom outlet of the packed bed 11, and are used for adjusting the cold storage and cold release processes.

[0044] The corresponding cold storage process cycle is: the cold quantity of the packed bed 11 has been released, the circulating air flows in the packed bed 11 in the direction from the packed bed outlet control valve 13 to the packed bed inlet control valve 12, the normal-temperature air flowing out of the packed bed 11 flows into the evaporator 17 through the packed bed inlet control valve 12 and the pipeline, in the process, the normal-temperature air absorbs cold quantity and is reduced in temperature to low-temperature air, the low-temperature air flows out of the evaporator 17 outlet, enters the bottom of the packed bed 11 through the pipeline and the packed bed outlet control valve 13, and gradually transfers the cold quantity to the packing medium, and is gradually changed in temperature to normal temperature to the upper end outlet of the packed bed, to complete a cold storage cycle, and the packed bed inlet control valve 12 and the packed bed outlet control valve 13 are closed after the system stops running.

[0045] The corresponding cold storage process cycle is: the cold quantity of the packed bed 11 has been released, the circulating air flows in the packed bed 11 in the direction from the packed bed outlet control valve 13 to the packed bed inlet control valve 12, the normal-temperature air flowing out of the packed bed 11 flows into the evaporator 17 through the packed bed inlet control valve 12 and the pipeline, in the process, the normal-temperature air absorbs cold quantity and is reduced in temperature to low-temperature air, the low-temperature air flows out of the evaporator 17 outlet, enters the bottom of the packed bed 11 through the pipeline and the packed bed outlet control valve 13, and gradually transfers the cold quantity to the packing medium, and is gradually changed in temperature to normal temperature to the upper end outlet of the packed bed, to complete a cold storage cycle, and the packed bed inlet control valve 12 and the packed bed outlet control valve 13 are closed after the system stops running.

[0046] The industrial steam high-temperature heat storage module is designed based on the continuous operation and water injection temperature reduction operation characteristics of industrial steam, and is used for storing high-quality sensible heat in industrial extraction steam of a thermal power generation system and generating power by using the high-quality sensible heat in a liquid air expansion power generation system. Specifically, the industrial steam high-temperature heat storage module includes a steam-molten salt heat exchanger 30, and the steam inlet and the steam outlet of the steam-molten salt heat exchanger 30 are correspondingly provided with a steam-molten salt heat exchanger inlet valve 29 and a steam-molten salt heat exchanger outlet valve 31, and the steam-molten salt heat exchanger 30, the steam-molten salt heat exchanger inlet valve 29 and the steam-molten salt heat exchanger outlet valve 31 are connected in parallel with a water injection temperature reducer 32 in the thermal power generation system, and in the operation process, the reheated extraction steam is cooled to the required temperature of the user by the steam-molten salt heat exchanger 30 and then supplied to the user.

[0047] The molten salt inlet of the steam-molten salt heat exchanger 30 is connected to a low-temperature molten salt tank 24. A thermal storage molten salt pump 25 is installed between the low-temperature molten salt tank 24 and the steam-molten salt heat exchanger 30. Specifically, the inlet of the thermal storage molten salt pump 25 is connected to the bottom of the low-temperature molten salt tank 24, and the outlet of the thermal storage molten salt pump 25 is connected to the molten salt inlet of the steam-molten salt heat exchanger 30. The thermal storage molten salt pump 25 is used to pump the low-temperature molten salt in the low-temperature molten salt tank 24 into the steam-molten salt heat exchanger 30. The molten salt outlet of the steam-molten salt heat exchanger 30 is connected to a high-temperature molten salt tank 21, and a molten salt heat storage bypass valve 26 is provided to adjust the temperature and flow rate of the molten salt entering the high-temperature molten salt tank 21. At the same time, the bottom outlet of the high-temperature molten salt tank 21 is connected to an exothermic molten salt pump 22, specifically connected to the inlet of the exothermic molten salt pump 22. The outlet of the exothermic molten salt pump 22 is connected via a pipeline to the molten salt inlets of the air-molten salt heater 19 and the air-molten salt reheater 20, respectively. The molten salt outlets of the air-molten salt heater 19 and the air-molten salt reheater 20 are both connected to the top inlet of the low-temperature molten salt tank 24. The exothermic molten salt pump 22 is used to pump the high-temperature molten salt in the high-temperature molten salt tank 21 into the air-molten salt heater 19 and the air-molten salt reheater 20, thereby enabling the high-temperature molten salt in the high-temperature molten salt tank 21 to heat the air through the air-molten salt heater 19 and the air-molten salt reheater 20 during the liquid air expansion power generation process before entering the low-temperature molten salt tank 24. At the same time, a molten salt exothermic bypass valve 23 is set to adjust the temperature and flow rate of the molten salt entering the low-temperature molten salt tank 24.

[0048] Corresponding thermal storage process operation mode:

[0049] The inlet valve 29 and outlet valve 31 of the steam-molten salt heat exchanger 30 are opened. At the same time, molten salt from the low-temperature molten salt tank 24 enters the steam-molten salt heat exchanger 30 via the thermal storage molten salt pump 25 to exchange heat with industrial extraction steam. The molten salt absorbs part of the sensible heat of the industrial extraction steam. After the industrial extraction steam meets the heat user's needs, it is supplied to the heat user. After the temperature of the molten salt rises, it enters the high-temperature molten salt tank 21 for storage. It should be noted that the molten salt flow rate during the thermal storage process is determined by the demand of the industrial steam user. The continuous operation of the thermal storage process does not conflict with the heat release process. It operates according to the user's needs. When the stored heat meets the heat required by the liquid air expansion and power generation system, the operation stops, the inlet valve 29 and outlet valve 31 of the steam-molten salt heat exchanger are closed, and the industrial steam supply switches to the original water spray desuperheating mode.

[0050] The corresponding high-temperature exothermic cycle is:

[0051] The high-temperature exothermic cycle corresponds to the liquid air expansion power generation process. The high-temperature molten salt from the high-temperature molten salt tank 21 enters the air-molten salt heater 19 and the air-molten salt reheater 20 after passing through the exothermic molten salt pump 22. After heating the air to the set temperature, it returns to the low-temperature molten salt tank 24, completing one exothermic cycle.

[0052] This invention discloses an operation method for a liquid air energy storage system thermoelectrically coupled to a thermal power unit, specifically including operation methods in the following scenarios:

[0053] A. Deep Peak Shaving Operation Method for Coupled Thermal Power Units

[0054] When thermal power units require deep peak shaving, and the unit's own electrical load cannot meet the grid requirements or the peak shaving ancillary service subsidies are substantial, assuming the grid's peak shaving command is P... w At this time, the thermal power generation system is operating normally, and the minimum electrical load that can be achieved is P. g P g >P w The electrical energy generated by thermal power units can be absorbed through a liquid air energy storage system, reducing the amount of electricity supplied to the grid by thermal power units. The liquid air energy storage system stores energy; the air compression liquefaction subsystem operates; the high-temperature compression heat storage module in the thermal cycle subsystem stores high-temperature compression heat; the low-temperature compression heat coupling regenerative system module operates; and the cold storage module releases cold. The liquid air expansion power generation system does not operate. The plant's power load is P. c The electrical load P that the liquid air energy storage system needs to absorb x =P g -P w -P c Accordingly, the total electrical load of the first compressor motor 2 and the second compressor motor 4 is P. x .

[0055] B. Peak Operation Methods for Combined Thermal Power Units

[0056] When a thermal power unit needs to meet peak demand or its output is limited due to other reasons and it encounters peak grid demand, assuming the grid's peak-shaving command is P... w At this point, the highest electrical load that the thermal power generation system can achieve is P. g P w >P g The electricity generated by the combined liquid air energy storage system can increase the grid-connected power of the thermal power unit. During this time, the thermal power generation system operates normally, the liquid air energy storage system releases energy, and correspondingly, the liquid air expansion generation system starts operating. The high-temperature compression heat storage module in the thermal cycle subsystem releases heat, the cold storage module stores cold energy, and the industrial steam high-temperature heat storage module releases heat. The air compression liquefaction subsystem and the low-temperature compression heat coupling regenerative system module are not operating. The plant power load is P. c Then, in the liquid air energy storage system, the electrical load P that the liquid air expansion generator system needs to generate is... k =P w -P g -P c, the power generation load of the air expansion generator 28 is P k .

[0057] C1. Deep peak shaving operation method of combined thermal power generating unit in heat supply condition

[0058] In the heat supply condition, the heat supply of the external network is Q w , the thermal power generating unit cannot meet the deep peak shaving requirement of the power grid due to heat supply, assuming that the power grid instruction is P w , at this time, the thermal power generating system is operated to meet the minimum electric load P w that can be reached under the heat supply of Q g , P g >P w , the electric energy generated by the liquid air energy storage system can be consumed to reduce the on-grid electric energy of the thermal power generating unit, the liquid air energy storage system is operated to store energy, and the operation method and the electric load to be consumed are consistent with those in method A.

[0059] C2. Peak shaving operation method of combined thermal power generating unit in heat supply condition

[0060] In the heat supply condition, the heat supply of the external network is Q w , the thermal power generating unit cannot meet the peak shaving requirement of the power grid due to heat supply, assuming that the power grid instruction is P w , at this time, the thermal power generating system is operated to meet the maximum electric load P w that can be reached under the heat supply of Q g , P g P w , the electric energy generated by the combined liquid air energy storage system can be consumed to increase the on-grid electric energy of the thermal power generating unit, at this time, the thermal power generating system is normally operated, the liquid air energy storage system is operated to release energy, and the operation method and the power generation load of the air expansion generator 28 are consistent with those in method B.

[0061] D. Combined thermal power generating unit heat and power cogeneration operation method in extremely cold weather

[0062] In the extremely cold weather, the external network lacks heat and electricity, the thermal power generating unit is operated in the maximum heat supply condition, and the electric load is P w , the corresponding maximum heat supply is Q max , at this time, the electric load instruction of the power grid is P w , P g P w , the heat load demand of the heat network is Q w , Q w >Q max , then the corresponding electric load gap ΔP=P w -P g , the heat load gap is ΔQ=Q w -Q maxThe electricity generated by the combined liquid air energy storage system can increase the on-grid electricity of the thermal power generating unit, and the surplus compression heat of the high-temperature compression heat storage module can be used for heating. At this time, the liquid air expansion power generation system operates, the high-temperature compression heat storage module in the cold-heat circulation subsystem releases heat, the industrial steam high-temperature heat storage module releases heat, the water inlet valve 51 of the heating heat exchanger and the water outlet valve 50 of the heating heat exchanger are opened, and the heating heat exchanger 52 works. Part of the hot water from the high-temperature hot water tank 7 goes to the air-water heater 18 to heat the air, and part of the hot water goes to the heating heat exchanger 52 to jointly supply heat to the heat network heater 53, so that the power generation load of the air expansion generator 28 in the liquid air energy storage system is ΔP=P w -P g , and the heat released by the high-temperature compression heat storage module in the cold-heat circulation subsystem for external heating, except for the air inlet of the preheating air-salt heater 19, is ΔQ=Q max -Q w .

[0063] The operation method of the industrial steam high-temperature heat storage module is as follows:

[0064] The heat storage process of the industrial steam high-temperature heat storage module is independent of the energy storage and release processes of the liquid air energy storage system, and can be operated as long as the thermal power generating unit normally operates to supply industrial steam to the outside. The heat storage time of the industrial steam high-temperature heat storage module mainly depends on the demand of the heat user, and the heat release process mainly accompanies the release process of the liquid air energy storage system. The heat storage time M c of the industrial steam high-temperature heat storage module is calculated as follows:

[0065] Suppose the demand of the external industrial user for industrial steam is D1, t / h, and the demand parameter is P1, T1. According to the demand parameter, the corresponding enthalpy value H1, kJ / kg, is calculated. The parameters of the reheated steam of the thermal power generating unit are P c , T c , and the corresponding enthalpy value is H c , kJ / kg. Correspondingly, the heat storage power HG c of the industrial steam high-temperature heat storage module per hour is D1×(H c -H1) / 3.6, kW; according to the inlet flow of the air expander 27, the inlet and outlet parameters of the air-salt heater 19 and the air-salt reheater 20, the demand power of the high-temperature heat in the release process of the liquid air energy storage system can be obtained, which is HG f , and the release time of the liquid air energy storage system is M b .

[0066] According to the above parameters, the heat storage process operation time M c of the industrial steam high-temperature heat storage module is HG f ×M b / HGc In other time periods, the industrial steam high-temperature heat storage module does not store heat, and the industrial steam supply is switched to the original water spray desuperheating mode operation.

Claims

1. An operation method for a liquid air energy storage system thermoelectrically coupled to a thermal power unit, based on a liquid air energy storage system connected to the existing thermal power generation system of the thermal power unit for normal power generation, industrial steam, and civil heating, characterized in that: The liquid air energy storage system comprises an air compression and liquefaction subsystem for accommodating the electric load of a thermal power unit during energy storage and converting electric energy into liquid air for storage, a liquid air expansion power generation subsystem for generating power by using the liquid air to expand and do work during energy release and feeding the generated power to the grid together with the power generated by the thermal power unit, and a cold and heat circulation subsystem for realizing efficient storage and utilization of cold and heat during energy storage and release, the cold and heat circulation subsystem comprising a high-temperature compression heat storage module, a low-temperature compression heat coupled heat recovery system module, a cold storage module and an industrial steam high-temperature heat storage module. The high-temperature compression heat storage module is used for storing high-temperature compression heat in the air compression and liquefaction subsystem and supplying the high-temperature compression heat to the liquid air expansion power generation subsystem for power generation and to the thermal power generation subsystem for heat supply, and the high-temperature compression heat storage module comprises a normal-temperature water tank (6) for storing normal-temperature water and a high-temperature hot water tank (7) for storing high-temperature water discharged from the air compression and liquefaction subsystem. The low-temperature compression heat coupled heat recovery system module directly uses the low-temperature compression heat in the air compression and liquefaction subsystem for the heat recovery unit in the thermal power generation subsystem through a pipeline, and simultaneously introduces condensate water in the thermal power generation subsystem as the cooling medium of the air compression and liquefaction subsystem. The cold storage module is used for storing the cold released when the liquid air changes from liquid state to gaseous state during the operation of the liquid air expansion power generation subsystem and transferring the cold to the air compression and liquefaction subsystem during the operation of the air compression and liquefaction subsystem, and the cold storage module comprises a packed bed (11) for storing the cold. The industrial steam high-temperature heat storage module is used for storing high-quality sensible heat in the industrial extraction steam of the thermal power generation subsystem and supplying the high-quality sensible heat to the liquid air expansion power generation subsystem for power generation, and the industrial steam high-temperature heat storage module comprises a steam-salt heat exchanger (30) connected in parallel with a water injection desuperheater (32) in the thermal power generation subsystem and used for cooling the reheated extraction steam to a required temperature of a user and supplying the extraction steam to the user, a low-temperature molten salt tank (24) connected to the molten salt inlet of the steam-salt heat exchanger (30), and a high-temperature molten salt tank (21) connected to the molten salt outlet of the steam-salt heat exchanger (30), and the bottom outlet of the high-temperature molten salt tank (21) and the top inlet of the low-temperature molten salt tank (24) are connected to the liquid air expansion power generation subsystem. The method comprises the following operation methods under different scenarios: A. a coupled thermal power unit deep peak shaving operation method; When the thermal power unit needs to be deeply peaking, the unit's own electric load cannot meet the requirements of the power grid or the peaking auxiliary service subsidy is considerable, assuming that the peaking instruction of the power grid is P w , at this time the thermal power generation system is normally operated, and the minimum electric load that can be reached is P g , P g P w , the liquid air energy storage system absorbs the electric energy generated by the thermal power unit, reduces the on-grid electric quantity of the thermal power unit, the liquid air energy storage system stores energy, the air compression and liquefaction subsystem operates, the high-temperature compression heat storage module in the cold and heat circulation subsystem stores high-temperature compression heat, the low-temperature compression heat coupled backheat system module operates, the cold storage module releases cold, the liquid air expansion power generation subsystem does not operate, and the auxiliary power load is P c , then the electric load that needs to be absorbed by the liquid air energy storage system is P x = P g - P w - P c ;​ B. a combined thermal power unit peak shaving operation method; When the thermal power unit needs to peak or is limited by other reasons, and encounters the grid peak, assuming the grid peak instruction is P w , at this time the highest electrical load that the thermal power system can reach is P g , P w > P g , the power generated by the combined liquid air energy storage system increases the power of the thermal power unit, at this time the thermal power system is running normally, the liquid air energy storage system is discharging energy, accordingly, the liquid air expansion power generation system starts to run, the high-temperature compression heat storage module in the cold and heat circulation subsystem releases heat, the cold storage module stores cold, the industrial steam high-temperature heat storage module releases heat, the air compression liquefaction subsystem and the low-temperature compression heat coupling regenerative system module do not run, and the auxiliary power load is P c , then the electrical load that the liquid air expansion power generation system in the liquid air energy storage system needs to generate is P k = P w - P g - P c ;​ C1. a combined thermal power unit deep peak shaving operation method under a heat supply condition; In the heating condition, the heat supply of the outer network is Q w The thermal power unit cannot meet the requirement of deep peak shaving of the power grid due to the heat supply, and it is assumed that the grid instruction is P w At this time, the thermal power system can meet Q w The minimum electric load that can be reached under the heat supply is P g Operation, P g P w The liquid air energy storage system absorbs the electric energy generated by the thermal power unit, reduces the on-grid electric quantity of the thermal power unit, and the liquid air energy storage system stores energy, and the operation method and the electric load to be absorbed are consistent with those in method A.​ C2. a combined thermal power unit peak shaving operation method under a heat supply condition. In the heating mode, the heat supply of the outer network is Q w The thermal power unit cannot meet the peak requirement of the power grid due to the heat supply. Assuming that the grid instruction is P w At this time, the thermal power system can meet Q w The highest electric load that can be reached under the heat supply is P g Operation, P g < P w The electric energy emitted by the combined liquid air energy storage system increases the on-grid electric quantity of the thermal power unit. At this time, the thermal power system normally operates, and the liquid air energy storage system releases energy. The operation method and the electric generation load and method of the liquid air expansion power generation system are consistent with those in method B.

2. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 1, wherein: The air compression liquefaction subsystem comprises a first compressor (1) for compressing air and a second compressor (3) connected in series with the first compressor (1), a first compressor post-cooler (5) is arranged between the first compressor (1) and the second compressor (3) for cooling the exhaust gas of the first compressor (1), a second compressor post-cooler (8) is arranged behind the second compressor (3) for cooling the exhaust gas of the second compressor (3), and a liquefaction main heat exchanger (9) is arranged behind the second compressor post-cooler (8) for cooling the air coming out of the second compressor post-cooler (8); a low-temperature throttle valve (10), a gas-liquid separator (14) and a liquid air storage tank (15) are arranged in sequence behind the liquefaction main heat exchanger (9) to realize that the air cooled by the liquefaction main heat exchanger (9) passes through the low-temperature throttle valve (10) and the gas-liquid separator (14) and is stored in the liquid air storage tank (15) in the form of normal-pressure liquid; the first compressor (1) is connected with a first compressor motor (2), the second compressor (3) is connected with a second compressor motor (4), and the total power load of the first compressor motor (2) and the second compressor motor (4) is P x .

3. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 2, wherein: The liquid air expansion power generation system comprises, in sequence, a cryogenic liquid pump (16), an evaporator (17), an air-water heater (18), an air-salt heater (19), an air expander (27), an air-salt reheater (20), an air expansion generator (28) and an energy storage system transformer (43) connected behind a liquid air storage tank (15), so as to realize that the liquid air in the liquid air storage tank (15) is pressurized by the cryogenic liquid pump (16), enters the evaporator (17), becomes high-pressure normal-temperature air, is heated by the air-water heater (18) and the air-salt heater (19) in sequence, enters the air expander (27) to do work and drive the air expansion generator (28) to generate power; the power generation load of the air expansion generator (28) is P k The power sources of the first compressor motor (2) and the second compressor motor (4) are connected from the energy storage system transformer (43), and the high-voltage side of the energy storage system transformer (43) is also connected with the outlet or bus of a steam turbine generator (42) in a thermal power generation system, so as to realize that the air compression and liquefaction in the energy storage process absorbs the electric energy generated by the steam turbine generator in the thermal power generation system, the electric energy generated by the air expansion generator (28) in the energy release process is incorporated into the energy storage system transformer (43), and the electric energy generated by the steam turbine generator (42) in the thermal power generation system is jointly put on the grid.

4. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 3, wherein: The water inlet of the high-temperature hot water tank (7) is connected with the hot water outlet of the first compressor post-cooler (5), and the water outlet of the high-temperature hot water tank (7) is connected with the hot water inlet of the air-water heater (18), so that the high-temperature water in the high-temperature hot water tank (7) can be used to preliminarily heat air in the process of power generation of the liquid air expansion power generation system through the air-water heater (18); the water inlet of the normal-temperature water tank (6) is connected with the cold water outlet of the air-water heater (18), and the water outlet of the normal-temperature water tank (6) is connected with the cold water inlet of the first compressor post-cooler (5); the water outlet of the high-temperature hot water tank (7) is also connected with the hot water inlet of the heat supply heat exchanger (52) in the thermal power sub-system through a pipeline and a heat supply heat exchanger inlet valve (51) arranged on the pipeline, so that the high-temperature water in the high-temperature hot water tank (7) can be used to supply heat to the outside together with the thermal network heater (53) in the thermal power sub-system through the heat supply heat exchanger (52); the cold water outlet of the heat supply heat exchanger (52) is also connected with the water inlet of the normal-temperature water tank (6) through a pipeline and a heat supply heat exchanger outlet valve (50) arranged on the pipeline.

5. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 3, wherein: The low-temperature compression heat coupling regenerative system module is connected with the cold water inlet of the second compressor post-cooler (8) through a pipeline and the water outlet of the shaft seal heater (45) in the regenerative unit, and is connected with the inlet of the five low-pressure heaters (49) and the inlet of the six low-pressure heaters (48) in the regenerative unit through a pipeline and valves; the low-temperature compression heat coupling regenerative system module can select to introduce the condensed water in the second compressor post-cooler (8) into the inlet of the five low-pressure heaters (49) or the inlet of the six low-pressure heaters (48) according to the load of the thermal power sub-system.

6. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 3, wherein: The packed bed (11) is connected in parallel between the evaporator (17) and the liquefaction main heat exchanger (9) through a pipeline, and the inlet and outlet of the packed bed (11) are respectively provided with a packed bed inlet control valve (12) and a packed bed outlet control valve (13) for adjusting the cold storage and release process.

7. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 4, wherein: The industrial steam high-temperature heat storage module further comprises a steam-molten salt heat exchanger inlet valve (29) and a steam-molten salt heat exchanger outlet valve (31) arranged in one-to-one correspondence with the steam inlet and the steam outlet of the steam-molten salt heat exchanger (30); a heat storage molten salt pump (25) is arranged between the low-temperature molten salt tank (24) and the steam-molten salt heat exchanger (30) and used for pumping the low-temperature molten salt in the low-temperature molten salt tank (24) into the steam-molten salt heat exchanger (30); the bottom outlet of the high-temperature molten salt tank (21) is connected with a heat-releasing molten salt pump (22) connected with the molten salt inlets of the air-molten salt heater (19) and the air-molten salt reheater (20) respectively and used for pumping the high-temperature molten salt in the high-temperature molten salt tank (21) into the air-molten salt heater (19) and the air-molten salt reheater (20), and the molten salt outlets of the air-molten salt heater (19) and the air-molten salt reheater (20) are connected with the top inlet of the low-temperature molten salt tank (24) to realize that the high-temperature molten salt in the high-temperature molten salt tank (21) enters the low-temperature molten salt tank (24) after being heated by air in the air-molten salt heater (19) and the air-molten salt reheater (20) in the air expansion power generation system.

8. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 7, wherein: The method comprises the following operation methods in different scenarios: D. Operation method of combined heat and power supply of thermal power generating unit in extremely cold weather Under extremely cold weather, the external network is short of heat and electricity, the thermal power unit runs at the maximum heat supply condition, and the electric load is P w The corresponding maximum heat supply is Q max At this time, the electric load instruction of the power grid is P w , P g < P w The heat load demand of the heat network is Q w , Q w > Q max The corresponding electric load gap Δ P = P w - P g The heat load gap is Δ Q = Q w - Q max The electric energy generated by the joint liquid air energy storage system increases the on-grid electric quantity of the thermal power unit, and the surplus compression heat of the high-temperature compression heat storage module is used for heating at this time. The liquid air expansion power generation system runs, the high-temperature compression heat storage module in the cold-heat circulation subsystem releases heat, the industrial steam high-temperature heat storage module releases heat, the heating water inlet valve (51) and the heating water outlet valve (50) of the heat supply heat exchanger are opened, and the heat supply heat exchanger (52) works. The hot water from the high-temperature hot water tank (7) goes to the air-water heater (18) to heat the air, and a part goes to the heat supply heat exchanger (52) to jointly supply heat to the external heat network with the heat network heater (53). The power generation load of the air expansion generator (28) in the liquid air energy storage system is Δ P = P w - P g The heat released by the high-temperature compression heat storage module in the cold-heat circulation subsystem to the outside, except for the air entering the preheating air-salt heater (19), is Δ Q = Q max - Q w .

9. The method of operating a liquid air energy storage system coupled to a thermal power plant of claim 8, wherein: The operation method of the industrial steam high-temperature heat storage module is: The heat storage process of the industrial steam high-temperature heat storage module is independent of the energy storage and energy release processes of the liquid air energy storage system, and can be operated as long as the industrial steam is supplied to the outside by the thermal power generation system. The heat storage duration of the industrial steam high-temperature heat storage module mainly depends on the demand of the heat user, and the heat release process is mainly accompanied by the energy release process of the liquid air energy storage system. The heat storage duration of the industrial steam high-temperature heat storage module M c is calculated according to the following method: The industrial steam quantity set according to the external industrial user demand is D 1, t / h, the demand parameter is P 1, T 1, the corresponding enthalpy value calculated according to the demand parameter is H 1, kJ / kg, the parameter of the reheated steam of the thermal power generation system is P c , T c , the corresponding enthalpy value is H c , kJ / kg, correspondingly, the heat storage power of the industrial steam high-temperature heat storage module per hour is HG c = D 1×( H c - H 1) / 3.6, kW; according to the air inlet flow of the air expander (27), the inlet and outlet parameters of the air-molten salt heater (19) and the air-molten salt reheater (20), the demand power of the high-temperature heat in the discharging process of the liquid air energy storage system can be obtained HG f , the discharging duration of the liquid air energy storage system is M b ; According to the above parameters, the running time of the high-temperature heat storage module of industrial steam is obtained M c = HG f × M b / HG c , and the high-temperature heat storage module of industrial steam does not store heat during other periods, and the industrial steam supply is switched to the original water spray desuperheating mode.

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