Cogeneration unit start-stop peak regulation system based on liquid air energy storage and system minimum capacity configuration method

Abstract

The invention discloses a cogeneration unit start-stop peak regulation system based on liquid air energy storage and a system minimum capacity configuration method. Comprising a coal-fired unit power generation unit for producing electric energy, the liquid air energy storage unit is used for absorbing the electric energy of the coal-fired unit power generation unit and converting the electric energy into heat and liquid air for storage; the civil heat supply unit is used for supplying heat to the outside by utilizing heating extraction steam provided by the coal-fired unit power generation unit and surplus compression heat provided by the liquid air energy storage unit; high-voltage equipment of the liquid air energy storage unit is connected to the power generation end of the coal-fired unit power generation unit, and the civil heat supply unit is connected with the liquid air energy storage unit and the coal-fired unit power generation unit. And the civil heat supply unit is connected with a heat supply pipe network. According to the system, heat supply can be guaranteed, the start-stop peak regulation function can be achieved, meanwhile, the system redundancy is reduced with the minimum capacity configuration, and the initial investment is reduced.

Description

Technical Field

[0001] This invention relates to the field of liquid air energy storage technology, and more specifically to a start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage, and a method for configuring the minimum capacity of the system. Background Technology

[0002] The power system is undergoing an unprecedented and profound transformation. The core contradiction lies in the conflict between the intermittency of a high proportion of new energy sources and the need for safe and stable operation of the power system. As the traditional main power source, coal-fired power faces the dual pressure of "ensuring supply and meeting basic needs" and "low-carbon transformation". With the release of the "Implementation Plan for the Special Action to Upgrade the New Generation of Coal-fired Power (2025-2027)", the technical requirements for start-up and peak shaving of coal-fired power were clearly put forward for the first time. It encourages existing and newly built units with the necessary conditions to have safe and reliable start-up and peak shaving capabilities through adaptive transformation or targeted design and manufacturing. With the high proportion of new energy power connected to the grid, start-up and peak shaving of coal-fired power units will become the norm.

[0003] Equipping coal-fired power units with energy storage can both support the base load of coal-fired power plants and compensate for their inherent shortcomings through the flexibility of energy storage. Liquid air energy storage, as a large-capacity, geographically unrestricted, long-term energy storage technology, demonstrates a highly efficient synergistic effect with the flexible operation characteristics of coal-fired power units in their thermoelectric conversion. For combined heat and power (CHP) units, breaking through the "heat-driven power generation" operation mode during the heating season and achieving start-stop peak shaving functions under heating conditions will be one of the important goals of future coal-fired power unit retrofits. Currently, most flexible retrofits of coal-fired power units require modifications to high-pressure steam pipelines. Moreover, for the coal-fired power plants themselves, the problems brought to the units by start-stop peak shaving cannot be ignored, such as boiler heating surface cracks, oxide scale peeling, high-temperature corrosion, and turbine rotor life loss, thus affecting equipment failures and lifespan. Therefore, to achieve start-stop peak shaving functions, CHP units must consider both unit safety and lifespan while also addressing residential heating needs.

[0004] Although configuring liquid air energy storage in cogeneration units can effectively improve the peak-shaving capacity of coal-fired power units, research on achieving peak-shaving during start-up and shutdown after configuring liquid air energy storage systems in units is still relatively scarce. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a start-stop peak-shaving system for cogeneration units based on liquid air energy storage and a method for configuring the minimum capacity of the system. This system enables cogeneration units to achieve intraday start-stop peak-shaving functions without shutting down, while also meeting the needs of civilian power supply. At the same time, it proposes a method for configuring the minimum capacity to minimize the initial investment.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0007] A cogeneration unit start-stop and peak-shaving system based on liquid air energy storage includes a coal-fired power generation unit for producing electricity, a liquid air energy storage unit for absorbing the electricity from the coal-fired power generation unit and converting it into heat and liquid air for storage, and a domestic heating unit for supplying external heat using heating steam provided by the coal-fired power generation unit and surplus compressed heat provided by the liquid air energy storage unit. The high-voltage equipment of the liquid air energy storage unit is connected to the power generation end of the coal-fired power generation unit, and the domestic heating unit is connected to both the liquid air energy storage unit and the coal-fired power generation unit. The domestic heating unit is connected to the heating network.

[0008] Further optimizing the technical solution, the coal-fired power generation unit includes a boiler and a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder, and a coal-fired generator connected in series on the steam pipe behind the boiler. The high-pressure equipment of the liquid air energy storage unit is connected to the power generation end of the coal-fired generator, and the heating extraction end of the civil heating unit is connected to the exhaust end of the steam turbine intermediate-pressure cylinder.

[0009] The technical solution is further optimized. The civil heating unit includes a recooler and a compression heat heater and a heating network heater that are connected in parallel and then in series with the recooler. The heating network heater is connected to the coal-fired power generation unit to form a first heating cycle. The compression heat heater is connected to the recooler and the liquid air energy storage unit to form a second heating cycle. The compression heat heater and the heating network heater are respectively connected to the heating pipeline network.

[0010] To further optimize the technical solution, the liquid air energy storage unit includes an energy storage module for storing cooled liquid air and a power generation module for generating electricity using the stored liquid air. The energy storage module and the power generation module are connected to the power generation end of the coal-fired power generation unit through an energy storage transformer.

[0011] To further optimize the technical solution, the energy storage module includes a first compressor and a second compressor connected in series. The first compressor and the second compressor are respectively connected to the energy storage transformer via a first compressor drive motor and a second compressor drive motor. The rear ends of the first compressor and the second compressor are respectively provided with a first compressor aftercooler and a second compressor aftercooler. The heat exchange end of the first compressor aftercooler is connected to a heat storage device. A liquefaction main heat exchanger is provided behind the second compressor aftercooler. The heat exchange end of the liquefaction main heat exchanger is connected to a cold storage device. A liquid air storage tank for storing liquid air is provided at the rear end of the liquefaction main heat exchanger.

[0012] The technical solution is further optimized. The power generation module includes a cryogenic pressurization pump, a vaporizer, a reheater, and an air expander connected in sequence behind the liquid air storage tank. The heat exchange end of the vaporizer is connected to the cold storage end of the cold storage device, the heat exchange end of the reheater is connected to the heat storage end of the heat storage device, and the air expander is connected to the energy storage transformer through the energy storage generator.

[0013] The minimum capacity configuration method for the start-up and peak-shaving system of a combined heat and power (CHP) unit based on liquid air energy storage, implemented based on the start-up and peak-shaving system of a CHP unit, includes the following steps: S1. Determine the instantaneous maximum heat load demand Q of the external network and the heating characteristic curve of the cogeneration unit; S2. Determine the minimum electrical load P1 corresponding to the heating steam extraction volume of the cogeneration unit under the condition of heat load Q; S3. Assume the initial value of the actual operating electrical load of the cogeneration unit is P2, where P2 < P1; S4. Determine the heating gap B1 of the cogeneration unit and the charging power A1 of the liquid air energy storage system; S5. Determine the capacity C and system parameters of the liquid air energy storage system based on the charging power of the liquid air energy storage system, and calculate the excess heat of compression in the system. This part of the heat of compression provides heat for the civil heating unit, and the heat supply is B2. S6. Calculate the deviation between the surplus compressed heat supply B2 and the heat supply gap B1 of the cogeneration unit. The calculation formula is: ; S7. Based on the calculation results in S6, determine the minimum liquid air energy storage capacity required to achieve the start-up, shutdown, and peak-shaving functions of the cogeneration unit under the condition of meeting heating demand, or return to modify the parameters.

[0014] To further optimize the technical solution, in step S1, the instantaneous maximum heating load demand Q is determined based on the external grid heating area K and the heating heat index q, where Q = Kq; and based on the test results of the heating characteristics of the cogeneration unit and the actual operating conditions, combined with the unit's design extraction steam condition diagram, different electrical loads P are determined. x The corresponding maximum heating steam extraction rate D curve is used to determine the functional relationship between the two, where D = f(P). x ).

[0015] To further optimize the technical solution, in step S4, based on the relationship curves between different electrical loads and steam extraction in step S1, the maximum heat supply Q1 that the cogeneration unit can provide under the electrical load P2 condition is determined, and compared with the instantaneous maximum heat supply load demand Q in step S1, the heat supply gap B1 is obtained, where B1=Q-Q1. Under electrical load condition P2, calculate the electrical load A1 that the liquid air energy storage system needs to absorb, assuming the combined heat and power unit's on-grid load is zero. A1 = P2 - P t , where P t A1 is the charging power of the liquid air energy storage system, which is the sum of the electricity loads of the cogeneration unit for both production and non-production plant use.

[0016] To further optimize the technical solution, in step S7, when the calculation result in step S6 is... The result converges and the process ends. The capacity C and system parameters of the liquid air energy storage system in step S5 are the minimum capacity of liquid air energy storage required to achieve the start-up and peak-shaving function of the cogeneration unit under the condition of meeting the heating demand. When the calculation result in step S6 is If the result does not converge, return to step S3 and modify the assumed initial value P2 of the actual operating electrical load of the unit. Modifying the initial value of P2 means increasing the initial value until the convergence result is met, and the process ends.

[0017] The technological advancements achieved by this invention are as follows, thanks to the adoption of the above technical solutions.

[0018] The present invention provides a start-stop peak-shaving system for cogeneration units based on liquid air energy storage and a method for configuring the minimum capacity of the system. This system enables the unit to reduce its on-grid electricity consumption to zero without shutting down, thus achieving start-stop peak-shaving functionality. Furthermore, considering the external heating demand of the cogeneration unit, a minimum capacity configuration method is proposed based on the actual heating characteristic curve of the unit to configure liquid air energy storage for start-stop peak-shaving while ensuring the maximum heating load of the external grid. This method guarantees heating supply, achieves start-stop peak-shaving functionality, and reduces system redundancy and initial investment with a minimum capacity configuration. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a flowchart of the minimum capacity configuration method for liquid air energy storage in this invention; Figure 3 This is a heating characteristic curve diagram determined by the unit heating load characteristic test and combined with the extraction steam condition diagram in the embodiment of the present invention.

[0020] Among them: 100. Liquid air energy storage unit, 101. First compressor, 102. First compressor drive motor, 103. Second compressor, 104. Second compressor drive motor, 105. First compressor aftercooler, 106. Second compressor aftercooler, 107. Liquefaction main heat exchanger, 108. Liquid air storage tank, 109. Cryogenic pressurization pump, 110. Vaporizer, 111. Cold storage device, 112. Reheater, 113. Heat storage device, 114. Air expander, 115. Energy storage generator, 116. Energy storage transformer; 200. Residential heating unit; 201. Recooler; 202. Compression heat heater; 203. Heat network heater; 300. Coal-fired power generation unit; 301. Boiler; 302. High-pressure cylinder of steam turbine; 303. Intermediate-pressure cylinder of steam turbine; 304. Low-pressure cylinder of steam turbine; 305. Coal-fired generator. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] A start-up and peak-shaving system for cogeneration units based on liquid air energy storage, combined with Figure 1 As shown, the system includes a coal-fired power generation unit 300, a liquid air energy storage unit 100, and a domestic heating unit 200. The high-voltage equipment of the liquid air energy storage unit 100 is connected to the power generation end of the coal-fired power generation unit 300. The domestic heating unit 200 is connected to both the liquid air energy storage unit 100 and the coal-fired power generation unit 300, and is also connected to the heating network.

[0023] The coal-fired power generation unit 300 is used to generate electricity normally and provide heating steam for the residential heating unit 200. The liquid air energy storage unit 100 is used to absorb the electrical load of the coal-fired power unit, converting electrical energy into heat and storing liquid air. During operation, it absorbs the electrical energy of the coal-fired power generation unit 300 during peak-shaving periods when the coal-fired power unit needs to start and stop, reducing the power grid connection of the unit to zero. This enables peak-shaving and start-stop operation without shutting down the unit. At the same time, the excess compressed heat from the energy storage process is supplied to the residential heating unit 200. During peak periods when the coal-fired power generation unit 300 needs to release energy, the liquid air is pressurized, heated, and expanded to generate electricity, which is then fed into the grid along with the electricity generated by the coal-fired power unit. The residential heating unit 200 provides external heating by utilizing the heating steam provided by the coal-fired power generation unit 300 and the excess compressed heat provided by the liquid air energy storage unit 100.

[0024] The coal-fired power generation unit 300 includes a boiler 301, a high-pressure cylinder 302 of a steam turbine, an intermediate-pressure cylinder 303 of a steam turbine, a low-pressure cylinder 304 of a steam turbine, and a coal-fired generator 305. A liquid air energy storage unit is connected to the rear end of the coal-fired generator 305. The heating extraction section of the domestic heating unit 200 is connected to the exhaust end of the steam turbine. The heating extraction steam for domestic heating is extracted from the exhaust end of the intermediate-pressure cylinder 303 of the steam turbine. The high-pressure cylinder 302, the intermediate-pressure cylinder 303, and the low-pressure cylinder 304 of the steam turbine jointly drive the coal-fired generator 305 to generate electricity.

[0025] The civil heating unit 200 includes a recooler 201, a compression heat heater 202, and a heating network heater 203. The compression heat heater 202 and the heating network heater 203 are connected in parallel and then connected in series with the recooler 201. The civil heating unit 200 includes two heating cycles during the external heating process. The heating network heater 203 is connected to the coal-fired power generation unit 300 to form the first heating cycle. The compression heat heater 202 is connected to the recooler 201 and the liquid air energy storage unit 100 to form the second heating cycle. The compression heat heater 202 and the heating network heater 203 are respectively connected to the heating pipeline network. The first heating cycle and the second heating cycle are connected in parallel. The heat source for the first heating cycle is the heating extraction steam from the intermediate pressure cylinder 303 of the steam turbine. After the heating extraction steam exchanges heat with the return water of the heating network through the heating network heater 203, the condensate returns to the coal-fired power generation unit 300, forming the first heating cycle. The heat source for the second heating cycle is part of the compression heat in the liquid air energy storage unit 100. The recooler 201, the second compressor aftercooler 106, and the compression heat heater 202 form a circulation loop. The closed-loop medium flows out from the recooler 201, enters the second compressor aftercooler 106, exchanges heat with the high-temperature compressor exhaust gas, and then enters the compression heat heater 202 to heat the return water of the heating network. After entering the recooler 201, the temperature is further reduced, completing one cycle. The return water of the heating network is divided into the heating network heater 203 and the compression heat heater 202, and after the temperature rises, they are used to supply heat to the outside.

[0026] The liquid air energy storage unit 100 includes an energy storage module and a power generation module. The energy storage module is used to store cooled liquid air, and the power generation module is used to generate electricity using the stored liquid air. The energy storage module and the power generation module are connected to the power generation end of the coal-fired generator 305 through an energy storage transformer 116.

[0027] The energy storage module includes a first compressor 101 and a second compressor 103 connected in series. The first compressor 101 and the second compressor 103 are respectively connected to the energy storage transformer 116 via a first compressor drive motor 102 and a second compressor drive motor 104. A first compressor aftercooler 105 is provided between the first compressor 101 and the second compressor 103 to cool the exhaust gas of the first compressor 101, and the first compressor aftercooler 105 is connected to the heat storage end of the heat storage device 113. A second compressor aftercooler 106 is provided after the second compressor 103 to cool the exhaust gas of the second compressor 103, and is connected to the civil heating unit 200. This part of the compression heat is used for civil heating. A liquefaction main heat exchanger 107 is provided after the second compressor aftercooler 106, wherein the cold release end of the cold storage device 111 is connected to the liquefaction main heat exchanger 107 to cool and liquefy the air coming out of the second compressor aftercooler 107 and store it in a liquid air storage tank 108 in a low-pressure liquid form.

[0028] The number of compressors in the energy storage module includes, but is not limited to, the first compressor 101 and the second compressor 103. The exhaust temperature of each compressor is determined according to specific process parameters. The heat storage device 113 stores high-quality compression heat for the power generation process. The excess compression heat at a lower temperature provides heat to the civil heating unit 200. In this embodiment, the exhaust temperature of the first compressor 101 is higher than that of the second compressor 103 and the second compressor 103 has excess compression heat. The number of compressors, the number of compression stages, and the connection method are not limited to those mentioned in this embodiment.

[0029] The power generation module includes a cryogenic pressurization pump 109, a vaporizer 110, a reheater 112, and an air expander 114 connected sequentially to the liquid air storage tank 108. This allows the liquid air in the liquid air storage tank 108 to be pressurized by the cryogenic pressurization pump 109 and then enter the vaporizer 110 to become high-pressure gaseous air. At the same time, the cold storage end of the cold storage device 111 is connected to the vaporizer 110 to store the cold energy when the liquid air is vaporized from liquid to gaseous state and release the cold energy during the power storage process. The high-pressure gaseous air is heated by the reheater 112 and then enters the air expander 114 to do work. The reheater 112 is connected to the heat release end of the heat storage device 113. The air expander 114 is connected to the energy storage transformer 116 through the energy storage generator 115. The power generated by the air expander 114 driving the energy storage generator 115 is fed into the energy storage transformer 116 and connected to the grid along with the power generated by the coal-fired power generation unit 300.

[0030] The minimum capacity configuration method for the start-up and peak-shaving system of a combined heat and power (CHP) unit based on liquid air energy storage is implemented through the start-up and peak-shaving system of the CHP unit based on liquid air energy storage, and its flowchart is as follows. Figure 2 As shown, it includes the following steps: S1. Determine the instantaneous maximum heat load demand Q of the external network and the heating characteristic curve of the cogeneration unit.

[0031] Based on the external heating area K and the heating index q, the instantaneous maximum heating load demand Q is determined, where Q = Kq; and based on the test results of the heating characteristics of the cogeneration unit and the actual operating conditions, combined with the unit's design extraction steam condition diagram, the different electrical loads P are determined. x The corresponding maximum heating steam extraction rate D curve is used to determine the functional relationship between the two, where D = f(P). x ).

[0032] S2. Determine the minimum electrical load P1 corresponding to the heating steam extraction volume of the cogeneration unit under the condition of heat load Q.

[0033] Based on the heating load Q in step S1, determine the required heating steam extraction volume D for the cogeneration unit, and then determine the minimum electrical load P1 of the cogeneration unit that can meet the heating load Q based on the relationship curve between different electrical loads and steam extraction volume determined in S1.

[0034] S3. Assume that the initial value of the actual operating electrical load of the cogeneration unit is P2, where P2 < P1.

[0035] S4. Determine the heating gap B1 of the cogeneration unit and the charging power A1 of the liquid air energy storage system.

[0036] Based on the relationship curves between different electrical loads and steam extraction in step S1, the maximum heat supply Q1 that the coal-fired power unit can provide under the electrical load P2 condition is determined, and compared with the instantaneous maximum heat supply load demand Q in step S1, the heat supply gap B1 is obtained, where B1 = Q - Q1. Under electrical load condition P2, calculate the electrical load A1 that the liquid air energy storage system needs to absorb, assuming the combined heat and power unit's on-grid load is zero. A1 = P2 - P t , where P t A1 is the charging power of the liquid air energy storage system, which is the sum of the electricity loads of the cogeneration unit for both production and non-production plant use.

[0037] S5. Determine the capacity C and system parameters of the liquid air energy storage system based on the charging power of the liquid air energy storage system, and calculate the excess compression heat in the system. This part of the compression heat provides heat for the civil heating unit, and the heat supply is B2.

[0038] S6. Calculate the deviation between the surplus compressed heat supply B2 and the heat supply gap B1 of the cogeneration unit. The calculation formula is: .

[0039] S7. Based on the calculation results in S6, determine the minimum liquid air energy storage capacity required to achieve the start-up, shutdown, and peak-shaving functions of the cogeneration unit under the condition of meeting heating demand, or return to modify the parameters.

[0040] When the calculation result in step S6 is The result converges and the process ends. The capacity C and system parameters of the liquid air energy storage system in step S5 are the minimum capacity of liquid air energy storage required to achieve the start-up and peak-shaving function of the cogeneration unit under the condition of meeting the heating demand. When the calculation result in step S6 is If the result does not converge, return to step S3 and modify the assumed initial value P2 of the actual operating electrical load of the unit. Modifying the initial value of P2 means increasing the initial value until the convergence result is met, and the process ends.

[0041] The effects of implementing the present invention will be illustrated below with specific embodiments.

[0042] Unit 1 of a power plant is a 330MW subcritical, extraction-heating, wet condensing steam turbine. The turbine uses five-stage extraction steam as the source of extraction steam for domestic heating, with a rated extraction steam pressure of 0.43MPa and a rated extraction steam capacity of 550t / h.

[0043] The heating area supplied by this unit is 6 million m². 2 7 million m 2 8 million m 2 Heating heat index 42W / m 2 For example, the heating characteristic curve determined based on the unit's heating load characteristic test and combined with the extraction steam condition diagram is as follows: Figure 3 As shown in the figure, line BC represents the minimum electrical load curve under different steam extraction conditions. The storage duration of the liquid air energy storage system can be determined according to the start-up and shutdown peak shaving requirements and the duration of peak and valley periods. In this embodiment, it is temporarily calculated that the coal-fired power unit maintains zero on-grid electricity for 6 hours, and the power generation duration is 5-6 hours. According to the method described in this invention, under the condition of meeting the unit's heating requirements, the minimum capacity calculation data of the liquid air energy storage required to realize the start-up and shutdown peak shaving function is shown in Table 1.

[0044]

Claims

1. A start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage, characterized in that: It includes a coal-fired power generation unit (300) for generating electricity, a liquid air energy storage unit (100) for consuming the electricity generated by the coal-fired power generation unit (300) and converting the electricity into heat and liquid air for storage, and a domestic heating unit (200) for supplying heat to the outside world using the heating steam provided by the coal-fired power generation unit (300) and the surplus compressed heat provided by the liquid air energy storage unit (100). The high-pressure equipment of the liquid air energy storage unit (100) is connected to the power generation end of the coal-fired power generation unit (300), and the domestic heating unit (200) is connected to the liquid air energy storage unit (100) and the coal-fired power generation unit (300) respectively; the domestic heating unit (200) is connected to the heating pipeline network.

2. The start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage according to claim 1, characterized in that: The coal-fired power generation unit (300) includes a boiler (301) and a steam turbine high-pressure cylinder (302), a steam turbine intermediate-pressure cylinder (303), a steam turbine low-pressure cylinder (304) and a coal-fired generator (305) connected in series on the steam pipe behind the boiler (301). The high-pressure equipment of the liquid air energy storage unit (100) is connected to the power generation end of the coal-fired generator (305), and the heating extraction end of the civil heating unit (200) is connected to the exhaust end of the steam turbine intermediate-pressure cylinder (303).

3. The start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage according to claim 1, characterized in that: The civil heating unit (200) includes a recooler (201), a compression heat heater (202) connected in parallel and then connected in series with the recooler (201), and a heat network heater (203). The heat network heater (203) is connected to the coal-fired power generation unit (300) to form a first heating cycle. The compression heat heater (202) is connected to the recooler (201) and the liquid air energy storage unit (100) to form a second heating cycle. The compression heat heater (202) and the heat network heater (203) are respectively connected to the heating pipeline network.

4. The start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage according to claim 1, characterized in that: The liquid air energy storage unit (100) includes an energy storage module for storing cooled liquid air and a power generation module for generating electricity using the stored liquid air. The energy storage module and the power generation module are connected to the power generation end of the coal-fired power generation unit (300) through an energy storage transformer (116).

5. The start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage according to claim 4, characterized in that: The energy storage module includes a first compressor (101) and a second compressor (103) connected in series. The first compressor (101) and the second compressor (103) are connected to the energy storage transformer (116) through the first compressor drive motor (102) and the second compressor drive motor (104), respectively. The first compressor (101) and the second compressor (103) are respectively provided with a first compressor aftercooler (105) and a second compressor aftercooler (106). The heat exchange end of the first compressor aftercooler (105) is connected to a heat storage device (113). The second compressor aftercooler (106) is provided with a liquefaction main heat exchanger (107). The heat exchange end of the liquefaction main heat exchanger (107) is connected to a cold storage device (111). The rear end of the liquefaction main heat exchanger (107) is provided with a liquid air storage tank (108) for storing liquid air.

6. The start-up and peak-shaving system for a combined heat and power unit based on liquid air energy storage according to claim 5, characterized in that: The power generation module includes a cryogenic pressurization pump (109), a vaporizer (110), a reheater (112), and an air expander (114) connected in sequence behind the liquid air storage tank (108). The heat exchange end of the vaporizer (110) is connected to the cold storage end of the cold storage device (111), the heat exchange end of the reheater (112) is connected to the heat storage end of the heat storage device (113), and the air expander (114) is connected to the energy storage transformer (116) through the energy storage generator (115).

7. A method for configuring the minimum capacity of a cogeneration unit start-up and shutdown peak-shaving system based on liquid air energy storage, implemented based on the cogeneration unit start-up and shutdown peak-shaving system described in any one of claims 1 to 6, characterized in that: Includes the following steps: S1. Determine the instantaneous maximum heat load demand Q of the external network and the heating characteristic curve of the cogeneration unit; S2. Determine the minimum electrical load P1 corresponding to the heating steam extraction volume of the cogeneration unit under the condition of heat load Q; S3. Assume the initial value of the actual operating electrical load of the cogeneration unit is P2, where P2 < P1; S4. Determine the heating gap B1 of the cogeneration unit and the charging power A1 of the liquid air energy storage system; S5. Determine the capacity C and system parameters of the liquid air energy storage system based on the charging power of the liquid air energy storage system, and calculate the excess heat of compression in the system. This part of the heat of compression provides heat for the civil heating unit, and the heat supply is B2. S6. Calculate the deviation between the surplus compressed heat supply B2 and the heat supply gap B1 of the cogeneration unit. The calculation formula is: ； S7. Based on the calculation results in S6, determine the minimum liquid air energy storage capacity required to achieve the start-up, shutdown, and peak-shaving functions of the cogeneration unit under the condition of meeting heating demand, or return to modify the parameters.

8. The minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration unit based on liquid air energy storage as shown in claim 7, characterized in that: In step S1, the instantaneous maximum heating load demand Q is determined based on the external grid heating area K and the heating index q, where Q = Kq; and different electrical loads P are determined based on the heating characteristic test results and actual operating conditions of the cogeneration unit, combined with the unit's design extraction steam condition diagram. x The corresponding maximum heating steam extraction rate D curve is used to determine the functional relationship between the two, where D = f(P). x ).

9. The minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration unit based on liquid air energy storage as shown in claim 7, characterized in that: In step S4, based on the relationship curves between different electrical loads and steam extraction in step S1, the maximum heat supply Q1 that the cogeneration unit can provide under the electrical load P2 condition is determined, and compared with the instantaneous maximum heat supply load demand Q in step S1, the heat supply gap B1 is obtained, where B1 = Q - Q1. Under electrical load condition P2, calculate the electrical load A1 that the liquid air energy storage system needs to absorb, assuming the combined heat and power unit's on-grid load is zero. A1 = P2 - P t , where P t A1 is the charging power of the liquid air energy storage system, which is the sum of the electricity loads of the cogeneration unit for both production and non-production plant use.

10. The minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration unit based on liquid air energy storage as described in claim 7, characterized in that: In step S7, when the calculation result in step S6 is The result converges and the process ends. The capacity C and system parameters of the liquid air energy storage system in step S5 are the minimum capacity of liquid air energy storage required to achieve the start-up and peak-shaving function of the cogeneration unit under the condition of meeting the heating demand. When the calculation result in step S6 is If the result does not converge, return to step S3 and modify the assumed initial value P2 of the actual operating electrical load of the unit. Modifying the initial value of P2 means increasing the initial value until the convergence result is met, and the process ends.

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