A combined cooling, heating and power Carnot battery energy storage system and method

Abstract

The present invention discloses a combined cooling, heating and power Carnot battery energy storage system, comprising: a two-stage heat pump circulation unit, a heat storage circulation unit, a Rankine cycle unit, a cold storage circulation unit, and an LNG vaporization utilization unit. The two-stage heat pump circulation unit, the heat storage circulation unit, the cold storage circulation unit, and the LNG vaporization utilization unit are operated during the off-peak period of power grid consumption; the Rankine cycle unit is operated during the peak period of power grid consumption. The present invention applies the liquefied natural gas (LNG) vaporization process to the Carnot battery energy storage system, and constructs a new type of high-efficiency energy storage system that can realize the combined supply of cooling, heating and power, so as to achieve the purposes of alleviating the peak load of the power grid and ensuring the stability of energy supply.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a combined cooling, heating and power Carnot battery energy storage system and method coupled with liquefied natural gas vaporization. Background Art

[0002] With the continuous advancement of science and technology, the energy industry is facing higher requirements and challenges. The fossil fuels that traditional energy systems rely on are not easy to store, and the fluctuations and intermittent nature of renewable energy such as solar energy and wind energy have a huge impact on the safety and stability of the power system. The rapid development of renewable energy has made energy storage technology particularly important to solve the instability of intermittent renewable energy and ensure the continuity of energy supply. Energy storage technology stores excess energy and releases it when needed to smooth the load curve of the power network, reduce peak loads, reduce energy waste and improve energy utilization.

[0003] Currently, the main large-scale commercial energy storage technologies are pumped storage and compressed air storage, both of which have problems such as geographical restrictions, long construction periods and high initial investment costs. On a smaller scale, energy storage solutions such as supercapacitors, flywheels and batteries are used. However, due to the high unit capacity cost of these energy storage solutions and the inherent correlation between power and energy storage capacity, they are more suitable for short-term charging and discharging cycles.

[0004] In recent years, Carnot battery has emerged as a new type of thermomechanical energy storage technology. Carnot battery is a new energy storage technology based on thermoelectric conversion. It has attracted much attention due to its high energy conversion, good flexibility and stability, no geographical restrictions, and large-scale energy storage. It provides an effective solution for the efficient use of new energy.

[0005] A Chinese patent document with publication number CN118687270A discloses a cascade heat pump Carnot battery energy storage system for combined cooling, heating and power generation, including three subsystems: a cascade heat pump circulation unit, an organic Rankine cycle unit, and a cold and heat storage unit. When there is excess power in the power grid, based on the reverse Rankine cycle, the cascade heat pump circulation unit converts electrical energy into heat energy and cold energy at the same time, and stores them in the cold and heat storage unit through a heat exchanger. A heat exchanger is provided between the water heat storage unit and the organic Rankine cycle unit. When there is insufficient power in the power grid, the water heat storage unit drives the organic Rankine cycle unit to generate electricity through the heat exchanger with the stored heat energy and cold energy. At the same time, the water cold storage tank can meet conventional cooling needs, and the water heat storage tank can meet industrial heat needs.

[0006] A Chinese patent document with publication number CN116247828B discloses a Carnot battery and geothermal energy storage system, which includes a heat storage component, a power storage circulation system, a power generation circulation system and a geothermal heat exchange system. During the transition season, the temperature fluctuates greatly, and the low-temperature and low-pressure liquid flows to the geothermal heat exchange system for heat exchange and temperature increase during the charging process; the temperature is lower in winter and the soil temperature is relatively high. During the charging process, the low-temperature and low-pressure liquid flowing out of the pressure reducing mechanism flows to the geothermal heat exchange system for heat exchange and temperature increase.

[0007] However, the existing Carnot battery energy storage technology has a single energy utilization method, poor energy supply flexibility, and high dependence on purchasing electricity from the power grid, resulting in low system cycle efficiency, low economy, and a long return on investment period. Summary of the invention

[0008] The present invention provides a combined cooling, heating and power Carnot battery energy storage system coupled with liquefied natural gas vaporization. The liquefied natural gas (LNG) vaporization process is applied to the Carnot battery energy storage system to construct a new type of high-efficiency energy storage system that can realize the combined supply of cooling, heating and power, so as to achieve the purposes of alleviating the peak load of the power grid and ensuring the stability of energy supply.

[0009] The technical solution of the present invention is as follows:

[0010] A combined cooling, heating and power Carnot battery energy storage system, comprising:

[0011] A two-stage heat pump circulation unit comprises a first-stage compressor (1), an LNG-heat pump working fluid heat exchanger (2), a second-stage compressor (3), a combustion heater (4), a heat pump working fluid-heat storage medium heat exchanger (5), a pressure reducing valve (6), and an evaporator (7) which are connected end to end by pipelines in sequence, forming a closed cycle;

[0012] The heat storage circulation unit comprises a high-temperature pump (8), a high-temperature heat storage tank (9), a heat storage medium-working fluid heat exchanger (10), and a heat storage tank (11) which are connected end to end by a pipeline in sequence, forming a closed cycle;

[0013] The Rankine cycle unit comprises an expander (12), a regenerator (13), a working medium-cold storage medium heat exchanger (14), and a working medium pump (15) which are connected end to end by pipelines in sequence, forming a closed cycle;

[0014] The cold storage circulation unit comprises a cold storage tank (16), an LNG-cold storage medium heat exchanger (17), a low temperature pump (18), and a low temperature cold storage tank (19) which are connected end to end by pipelines in sequence, forming a closed cycle;

[0015] An LNG vaporization and utilization unit comprises an LNG storage tank (20), an LNG pump (21), an LNG expander (22), and a natural gas pipeline network (23) which are sequentially connected in series via pipelines.

[0016] Preferably, in the heat storage circulation unit, the outlet of the heat storage tank (11) is connected to the cold end inlet of the heat pump working fluid-heat storage medium heat exchanger (5), and the cold end outlet of the heat pump working fluid-heat storage medium heat exchanger (5) is connected to the inlet of the high-temperature pump (8).

[0017] Preferably, in the Rankine cycle unit, the cold end outlet of the regenerator (13) is connected to the cold end inlet of the heat storage medium-working fluid heat exchanger (10), and the cold end outlet of the heat storage medium-working fluid heat exchanger (10) is connected to the inlet of the expander (12).

[0018] Preferably, in the cold storage circulation unit, the outlet of the low-temperature cold storage tank (19) is connected to the cold end inlet of the working fluid-cold storage medium heat exchanger (14), and the cold end outlet of the working fluid-cold storage medium heat exchanger (14) is connected to the inlet of the cold storage tank (16).

[0019] Preferably, in the LNG vaporization utilization unit, the outlet of the LNG pump (21) is connected to the cold end inlet of the LNG-cold storage medium heat exchanger (17), the cold end outlet of the LNG-cold storage medium heat exchanger (17) is connected to the cold end inlet of the LNG-heat pump working fluid heat exchanger (2), the cold end outlet of the LNG-heat pump working fluid heat exchanger (2) is connected to the inlet of the LNG expander (22), and the outlet of the LNG expander (22) is connected to the natural gas pipeline network (23) on one side and to the combustion heater (4) on the other side.

[0020] In the two-stage heat pump circulation unit, the outlet of the first-stage compressor (1) is connected to the hot end inlet of the LNG-heat pump working fluid heat exchanger (2), the hot end outlet of the LNG-heat pump working fluid heat exchanger (2) is connected to the inlet of the second-stage compressor (3), the outlet of the second-stage compressor (3) is connected to the heating inlet of the combustion heater (4), the heating outlet of the combustion heater (4) is connected to the hot end inlet of the heat pump working fluid-heat storage medium heat exchanger (5), the hot end outlet of the heat pump working fluid-heat storage medium heat exchanger (5) is connected to the inlet of the pressure reducing valve (6), the outlet of the pressure reducing valve (6) is connected to the inlet of the evaporator (7), and the outlet of the evaporator (7) is connected to the inlet of the compressor (1), thereby forming a closed cycle.

[0021] In the heat storage cycle unit, the outlet of the heat storage tank (11) is connected to the cold end inlet of the heat pump working fluid-heat storage medium heat exchanger (5), the cold end outlet of the heat pump working fluid-heat storage medium heat exchanger (5) is connected to the inlet of the high temperature pump (8), the outlet of the high temperature pump (8) is connected to the inlet of the high temperature heat storage tank (9), the outlet of the high temperature heat storage tank (9) is connected to the hot end inlet of the heat storage medium-working fluid heat exchanger (10), and the hot end outlet of the heat storage medium-working fluid heat exchanger (10) is connected to the inlet of the heat storage tank (11), thereby forming a closed cycle.

[0022] In the Rankine cycle unit, the cold end outlet of the regenerator (13) is connected to the cold end inlet of the heat storage medium-working fluid heat exchanger (10), the cold end outlet of the heat storage medium-working fluid heat exchanger (10) is connected to the inlet of the expander (12), the outlet of the expander (12) is connected to the hot end inlet of the regenerator (13), the hot end outlet of the regenerator (13) is connected to the hot end inlet of the working fluid-cold storage medium heat exchanger (14), the hot end outlet of the working fluid-cold storage medium heat exchanger (14) is connected to the inlet of the working fluid pump (15), and the outlet of the working fluid pump (15) is connected to the cold end inlet of the regenerator (13), thereby forming a closed cycle.

[0023] In the cold storage circulation unit, the outlet of the cold storage tank (16) is connected to the hot end inlet of the LNG-cold storage medium heat exchanger (17), the hot end outlet of the LNG-cold storage medium heat exchanger (17) is connected to the inlet of the low-temperature pump (18), the outlet of the low-temperature pump (18) is connected to the inlet of the low-temperature cold storage tank (19), the outlet of the low-temperature cold storage tank (19) is connected to the cold end inlet of the working medium-cold storage medium heat exchanger (14), and the cold end outlet of the working medium-cold storage medium heat exchanger (14) is connected to the inlet of the cold storage tank (16), thereby forming a closed cycle.

[0024] In the LNG vaporization utilization unit, LNG is stored in an LNG storage tank (20), the outlet of the LNG storage tank (20) is connected to the inlet of an LNG pump (21), the outlet of the LNG pump (21) is connected to the cold end inlet of the LNG-cold storage medium heat exchanger (17), the cold end outlet of the LNG-cold storage medium heat exchanger (17) is connected to the cold end inlet of the LNG-heat pump working fluid heat exchanger (2), the cold end outlet of the LNG-heat pump working fluid heat exchanger (2) is connected to the inlet of an LNG expander (22), one outlet of the LNG expander (22) is connected to a natural gas pipeline network (23), and the other outlet is connected to a combustion heater (4).

[0025] Preferably, the circulating working fluid used in the two-stage heat pump circulation unit is R1234yf or R134a; and the evaporator (7) utilizes an air heat source for evaporation.

[0026] Preferably, in the heat storage circulation unit, the heat storage tank (11) and the high-temperature heat storage tank (9) both use high-pressure water with a pressure not less than 1 MPa, the temperature of the high-pressure water in the heat storage tank (11) is 20-80° C., and the temperature of the high-pressure water in the high-temperature heat storage tank (9) is 150-200° C., and the high-temperature pump (8) is used to compensate for the pressure loss of the high-pressure water in the heat storage circulation flow.

[0027] Preferably, the circulating working fluid used in the Rankine cycle unit is carbon dioxide, and the condensed liquid carbon dioxide circulating working fluid is pressurized to above 8 MPa by a working fluid pump (15), and the temperature of the carbon dioxide entering the expander (12) is not less than 150°C.

[0028] Preferably, the working fluid used in the cold storage circulation unit is pressurized liquid carbon dioxide, the boiling point of which is not higher than 0°C, the temperature of the liquid carbon dioxide in the cold storage tank (16) is not higher than -20°C, the temperature of the liquid carbon dioxide in the low-temperature cold storage tank (19) is -50 to -100°C, and the low-temperature pump (18) is used to compensate for the pressure loss of the liquid carbon dioxide in the cold storage circulation flow.

[0029] Preferably, the pressure of the liquefied gas in the LNG vaporization and utilization unit after being pressurized by the LNG pump (21) is 7 to 12 MPa, and the proportion of the natural gas entering the combustion heater (4) after being expanded by the LNG expander (22) does not exceed 20%.

[0030] The present invention also provides a combined cooling, heating and power Carnot battery energy storage method, comprising:

[0031] During the off-peak period of power grid electricity consumption, the two-stage heat pump circulation unit, the heat storage circulation unit, the cold storage circulation unit and the LNG vaporization utilization unit are operated;

[0032] During the peak period of power consumption in the power grid, the Rankine cycle unit is operated.

[0033] Preferably, part of the electricity consumed by the primary compressor (1) and the secondary compressor (3) during operation is derived from the power grid, and the electricity generated by the LNG expander (22) is used to compensate for the remaining electricity consumption.

[0034] Preferably, the electricity generated by the LNG expander (22) when in operation is used to compensate for the power consumption of the high-temperature pump (8), the working fluid pump (15), and the low-temperature pump (18), and the remaining electricity is used to be input into the power grid to smooth out the peak and valley power demand of the power grid.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] By coupling LNG cold energy and utilizing it in stages, the system can realize the trigeneration of cooling, heating and electricity, that is, providing electricity, heating and cooling at the same time, significantly improving the utilization efficiency of energy and having good economic efficiency. At the same time, the system is suitable for energy supply in multiple application scenarios, reducing energy costs, and contributing to energy conservation, carbon reduction and flexibility transformation of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of the combined cooling, heating and power Carnot battery energy storage system coupled with LNG of the present invention;

[0038] Figure 2 This is a flow chart of the working state of the power grid during the off-peak period of electricity consumption in the present invention;

[0039] Figure 3 This is a flow chart of the working state of the power grid during the peak period of power consumption in the present invention;

[0040] In the figure: 1. primary compressor; 2. LNG-heat pump working fluid heat exchanger; 3. secondary compressor; 4. combustion heater; 5. heat pump working fluid-heat storage medium heat exchanger; 6. pressure reducing valve; 7. evaporator; 8. high temperature pump; 9. high temperature heat storage tank; 10. heat storage medium-working fluid heat exchanger; 11. heat storage tank; 12. expander; 13. regenerator; 14. working fluid-cold storage medium heat exchanger; 15. working fluid pump; 16. cold storage tank; 17. LNG-cold storage medium heat exchanger; 18. low temperature pump; 19. low temperature cold storage tank; 20. LNG storage tank; 21. LNG pump; 22. LNG expander; 23. natural gas pipeline network. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0042] A combined heat and power Carnot battery energy storage system coupled with LNG cold energy, such as Figure 1 As shown, it includes: a two-stage heat pump circulation unit, a heat storage circulation unit, a Rankine cycle unit, a cold storage circulation unit and an LNG cold energy utilization unit.

[0043] The two-stage heat pump circulation unit is composed of a primary compressor 1, an LNG-heat pump working fluid heat exchanger 2, a secondary compressor 3, a combustion heater 4, a heat pump working fluid-heat storage medium heat exchanger 5, a pressure reducing valve 6, and an evaporator 7 connected in series in sequence. In the two-stage heat pump circulation unit, the heat pump working fluid is compressed and pressurized by the primary compressor 1, and then releases heat in the LNG-heat pump working fluid heat exchanger 2. The heat pump working fluid after cooling is compressed for the second time in the secondary compressor 3. The high-pressure heat pump working fluid after pressurization absorbs heat energy in the combustion heater 4, and condenses and releases heat in the heat pump working fluid-heat storage medium heat exchanger 5. After that, it is decompressed by the pressure reducing valve 6, and absorbs the environmental heat source in the evaporator 7 for vaporization, so as to enter the primary compressor 1 for a new round of two-stage heat pump circulation unit.

[0044] The heat storage cycle unit is composed of a high temperature pump 8, a high temperature heat storage tank 9, a heat storage medium-working fluid heat exchanger 10, a heat storage tank 11, and a heat pump working fluid-heat storage medium heat exchanger 5, which are connected in series in sequence. In the heat storage cycle unit, the heat storage medium in the heat storage tank 11 exchanges heat in the heat pump working fluid-heat storage medium heat exchanger 5 to obtain heat energy, and is stored in the high temperature heat storage tank 9 after being pressurized by the high temperature pump 8. The heat storage medium in the high temperature heat storage tank 9 releases heat energy in the heat storage medium-working fluid heat exchanger 10. The cooled heat storage medium is stored in the heat storage tank 11, so as to carry out a new round of heat storage cycle. The high temperature pump 8 is used to compensate for the pressure loss of high pressure water in the heat storage cycle flow.

[0045] The Rankine cycle unit is composed of a heat storage medium-working medium heat exchanger 10, an expander 12, a regenerator 13, a working medium-cold storage medium heat exchanger 14, and a working medium pump 15 connected in series in sequence. The liquid Rankine cycle working medium pressurized by the working medium pump 15 absorbs a small amount of heat energy in the regenerator 13, is heated and vaporized in the heat storage medium-working medium heat exchanger 10, and then enters the expander 12 for isentropic expansion to achieve external output of electricity. After the expanded working medium exhaust gas releases part of its heat energy in the regenerator 13, it is liquefied and condensed in the working medium-cold storage medium heat exchanger 14, and the condensed liquid working medium enters the working medium pump 15, thereby performing a new round of Rankine cycle.

[0046] The cold storage circulation unit is composed of a cold storage tank 16, an LNG-cold storage medium heat exchanger 17, a cryogenic pump 18, a low-temperature cold storage tank 19, and a working medium-cold storage medium heat exchanger 14, which are connected in series in sequence. In the cold storage circulation unit, the liquid cold storage medium in the low-temperature cold storage tank 19 releases cold energy in the working medium-cold storage medium heat exchanger 14, and the heated liquid cold storage medium is stored in the cold storage tank 16, and obtains cold energy in the LNG-cold storage medium heat exchanger 17, thereby performing a new round of Rankine cycle. The cryogenic pump 18 is used to compensate for the pressure loss of liquid carbon dioxide in the cold storage circulation flow.

[0047] The LNG vaporization and utilization unit is composed of an LNG storage tank 20, an LNG pump 21, an LNG-cold storage medium heat exchanger 17, an LNG-heat pump working medium heat exchanger 2, an LNG expander 22, and a natural gas pipeline 23, which are connected in series in sequence. In the LNG vaporization and utilization unit, the LNG in the LNG storage tank 20 is pressurized by the LNG pump 21 and then released in the LNG-cold storage medium heat exchanger 17. The vaporized natural gas absorbs heat in the LNG-heat pump working medium heat exchanger 2. The heated natural gas outputs electric energy to the outside in the LNG expander 22. This part of the electric energy is used for part of the power consumption of the primary compressor 1 and the secondary compressor 3 working in the same period; the expanded natural gas is transported in the natural gas pipeline 23, and no more than 20% of the natural gas enters the combustion heater 4 for combustion and heating.

[0048] When LNG in the LNG storage tank (20) is input into the system at a flow rate of 5 t / h, the -50°C low-temperature cold storage medium in the cold storage tank (16) can be cooled to -100°C at a rate of 10 t / h and stored in the low-temperature cold storage tank (19); the COP of the two-stage heat pump circulation unit reaches 3.8, and at the same time, the 10°C, 3.6 t / h heat storage medium in the heat storage tank (11) can be heated to 160°C and stored in the high-temperature heat storage tank (9).

[0049] In the above process, the two-stage heat pump cycle, heat storage cycle unit and cold storage cycle unit consume 120kW of electricity; the net output power of the Rankine cycle unit is 101kW; the net output power of the LNG vaporization utilization unit is 89kW, and the comprehensive performance index is as high as 3.258.

[0050] When the power grid is in the off-peak period, the two-stage heat pump circulation unit, the heat storage circulation unit, the cold storage circulation unit and the LNG vaporization utilization unit are operated, and the system stores energy, such as Figure 2 shown.

[0051] When the two-stage heat pump circulation unit is working: the first-stage compressor 1 compresses the low-pressure heat pump working fluid into high pressure. The high-pressure heat pump working fluid releases heat in the LNG-heat pump working fluid heat exchanger 2 to preheat the LNG. The second-stage compressor 3 further compresses the heat pump working fluid to increase its temperature and pressure. The combustion heater 4 provides additional heat energy to heat the high-pressure heat pump working fluid. In the heat pump working fluid-heat storage medium heat exchanger 5, the heat pump working fluid transfers heat to the heat storage medium. The pressure reducing valve 6 reduces the pressure of the heat pump working fluid to prepare it to absorb the ambient heat source in the evaporator 7. The evaporator 7 uses the air heat source to evaporate the heat pump working fluid and complete the cycle.

[0052] When the heat storage circulation unit is working: the high temperature pump 8 pressurizes the pressurized water heated in the heat pump working medium-heat storage medium heat exchanger 5 and transports it to the high temperature heat storage tank 9 for storage.

[0053] When the cold storage circulation unit is working: the low-temperature pump 18 pressurizes the low-temperature liquid carbon dioxide cooled in the LNG-cold storage medium heat exchanger 17 and transports it to the low-temperature cold storage tank 19 for storage.

[0054] When the LNG vaporization and utilization unit is working: the LNG in the LNG storage tank 20 is pressurized by the LNG pump 21. In the LNG-cold storage medium heat exchanger 17, the LNG releases cold energy to cool the cold storage medium. The LNG expander 22 expands the high-pressure natural gas, and the generated electricity is used to compensate for the system power consumption.

[0055] When the power grid is in peak demand, the system mainly operates the Rankine cycle unit to provide power, such as Figure 3 shown.

[0056] In the heat storage medium-working fluid heat exchanger 10, liquid carbon dioxide absorbs heat and is converted into high-temperature and high-pressure gas. The LNG expander 12 uses the expansion of high-temperature and high-pressure carbon dioxide to do work and generate electricity. In the regenerator 13, carbon dioxide releases part of the heat and the temperature drops. In the working fluid-cold storage medium heat exchanger 14, carbon dioxide releases the remaining heat and condenses into liquid. The liquid carbon dioxide is pressurized by the working fluid pump 15 to complete the cycle. During peak periods, the electricity generated by the LNG expander 12 can compensate for the power consumption of the system and input excess electricity into the power grid to meet the high load demand of the power grid.

[0057] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A combined cooling, heating and power Carnot battery energy storage system, characterized in that: include: A two-stage heat pump circulation unit comprises a first-stage compressor (1), an LNG-heat pump working fluid heat exchanger (2), a second-stage compressor (3), a combustion heater (4), a heat pump working fluid-heat storage medium heat exchanger (5), a pressure reducing valve (6), and an evaporator (7) which are connected end to end by pipelines in sequence, forming a closed cycle; The heat storage circulation unit comprises a high temperature pump (8), a high temperature heat storage tank (9), a heat storage medium-working fluid heat exchanger (10), and a heat storage tank (11) which are connected end to end in sequence by a pipeline to form a closed cycle; the outlet of the heat storage tank (11) is connected to the cold end inlet of the heat pump working fluid-heat storage medium heat exchanger (5), and the cold end outlet of the heat pump working fluid-heat storage medium heat exchanger (5) is connected to the inlet of the high temperature pump (8); The Rankine cycle unit comprises an expander (12), a regenerator (13), a working medium-cold storage medium heat exchanger (14), and a working medium pump (15) which are connected end to end by pipelines in sequence, forming a closed cycle; the cold end outlet of the regenerator (13) is connected to the cold end inlet of the heat storage medium-working medium heat exchanger (10), and the cold end outlet of the heat storage medium-working medium heat exchanger (10) is connected to the inlet of the expander (12); The cold storage circulation unit comprises a cold storage tank (16), an LNG-cold storage medium heat exchanger (17), a low temperature pump (18), and a low temperature cold storage tank (19) which are connected end to end by a pipeline to form a closed cycle; the outlet of the low temperature cold storage tank (19) is connected to the cold end inlet of the working medium-cold storage medium heat exchanger (14), and the cold end outlet of the working medium-cold storage medium heat exchanger (14) is connected to the inlet of the cold storage tank (16); The LNG vaporization utilization unit comprises an LNG storage tank (20), an LNG pump (21), an LNG expander (22), and a natural gas pipeline network (23) which are sequentially connected in series by pipelines; the outlet of the LNG pump (21) is connected to the cold end inlet of the LNG-cold storage medium heat exchanger (17), the cold end outlet of the LNG-cold storage medium heat exchanger (17) is connected to the cold end inlet of the LNG-heat pump working medium heat exchanger (2), the cold end outlet of the LNG-heat pump working medium heat exchanger (2) is connected to the inlet of the LNG expander (22), one outlet of the LNG expander (22) is connected to the natural gas pipeline network (23), and the other outlet is connected to the combustion heater (4).

2. The combined cooling, heating and power Carnot battery energy storage system according to claim 1, characterized in that: The circulating working fluid used by the two-stage heat pump circulation unit is R1234yf or R134a; the evaporator (7) uses air heat source for evaporation.

3. The combined cooling, heating and power Carnot battery energy storage system according to claim 1, characterized in that: In the heat storage circulation unit, the heat storage tank (11) and the high-temperature heat storage tank (9) both use high-pressure water with a pressure not less than 1 MPa, the temperature of the high-pressure water in the heat storage tank (11) is 20-80° C., and the temperature of the high-pressure water in the high-temperature heat storage tank (9) is 150-200° C. The high-temperature pump (8) is used to compensate for the pressure loss of the high-pressure water in the heat storage circulation flow.

4. The combined cooling, heating and power Carnot battery energy storage system according to claim 1, characterized in that: The circulating working fluid used in the Rankine cycle unit is carbon dioxide. The condensed liquid carbon dioxide circulating working fluid is pressurized to above 8 MPa by a working fluid pump (15), and the temperature of the carbon dioxide entering the expander (12) is not less than 150°C.

5. The combined cooling, heating and power Carnot battery energy storage system according to claim 1, characterized in that: The working fluid used in the cold storage circulation unit is pressurized liquid carbon dioxide, the boiling point of which is not higher than 0°C. The temperature of the liquid carbon dioxide in the cold storage tank (16) is not higher than -20°C. The temperature of the liquid carbon dioxide in the low-temperature cold storage tank (19) is -50 to -100°C. The low-temperature pump (18) is used to compensate for the pressure loss of the liquid carbon dioxide in the cold storage circulation flow.

6. The combined cooling, heating and power Carnot battery energy storage system according to claim 1, characterized in that: The pressure of the liquefied gas in the LNG vaporization and utilization unit is 7-12 MPa after being pressurized by the LNG pump (21), and the proportion of the natural gas entering the combustion heater (4) after being expanded by the LNG expander (22) does not exceed 20%.

7. A combined cooling, heating and power Carnot battery energy storage method, characterized in that: Based on the combined cooling, heating and power Carnot battery energy storage system according to any one of claims 1 to 6, it comprises: During the off-peak period of power grid electricity consumption, the two-stage heat pump circulation unit, the heat storage circulation unit, the cold storage circulation unit and the LNG vaporization utilization unit are operated; During the peak period of power consumption in the power grid, the Rankine cycle unit is operated.

8. The combined cooling, heating and power Carnot battery energy storage method according to claim 7, characterized in that: The power consumed by the first-stage compressor (1) and the second-stage compressor (3) during operation is partially derived from the power grid; the power generated by the LNG expander (22) during operation is used to compensate for the power consumption of the high-temperature pump (8), the working fluid pump (15), and the low-temperature pump (18), and the remaining power is input into the power grid.

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