Cfb boiler system and method for controlling the temperature of the flue gas

Abstract

The application discloses a kind of based on liquid air energy storage combined heat and power unit start-stop peak shaving system and system minimum capacity configuration method, including the coal-fired generating unit for producing electric energy, the electric energy for accommodating coal-fired generating unit and the electric energy is changed into heat and liquid air storage unit for storing liquid air energy storage unit and using coal-fired generating unit provided by heating extraction steam and the surplus compressed heat provided by liquid air energy storage unit carries out external heating civil heating unit, and the high-pressure equipment of liquid air energy storage unit is connected in the power generation end of coal-fired generating unit, and civil heating unit is connected with liquid air energy storage unit and coal-fired generating unit respectively;The civil heating unit is connected with heating pipe network.The application can not only guarantee heating, but also realize start-stop peak shaving function, with minimum capacity configuration, reduce system redundancy, and reduce initial investment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid air energy storage, more particularly to a thermal power cogeneration unit start-stop peak shaving system based on liquid air energy storage and a system minimum capacity configuration method. BACKGROUND

[0002] The power system is undergoing an unprecedented profound change, and the core contradiction lies in the contradiction between the intermittency of a high proportion of new energy and the safe and stable operation demand of the power system. Coal power, as the traditional main power source, is facing the dual pressure of "supplying the demand for basic needs" and "low-carbon transformation". With the release of the "New Generation Coal Power Upgrading Special Action Implementation Plan (2025-2027)", it is the first time to explicitly propose the technical requirements for coal power start-stop peak shaving, and encourage the existing units and newly-built units that meet the conditions to implement adaptive modification or targeted design and manufacturing, and have the ability of safe and reliable start-stop peak shaving. With the high proportion of new energy power connected to the power grid, coal power unit start-stop peak shaving will become the norm.

[0003] The configuration of energy storage for coal power units can not only play the role of base load support for coal power, but also make up for its inherent shortcomings with the flexibility of energy storage. As a large-capacity, geographically unrestricted long-time energy storage technology, the thermal-electric conversion flexible operation characteristics of liquid air energy storage and the flexibility of coal power unit modification show high efficiency of synergistic effect. For thermal power cogeneration units, breaking the operation mode of "heat determines electricity" during the heating period and realizing the start-stop peak shaving function under the heating condition will be one of the important goals of future modification of coal power units. At present, most of the flexible modification of coal power units requires modification of high-pressure steam pipes, and for coal power itself, the problems brought by start-stop peak shaving to the unit cannot be ignored, such as boiler heating surface cracks, oxide skin shedding, high-temperature corrosion, equipment failures and life of turbine rotor life loss, etc. Therefore, thermal power cogeneration units that want to realize the start-stop peak shaving function must consider the safety and life of the unit, as well as the problem of heating for the people.

[0004] Although the configuration of liquid air energy storage for thermal power cogeneration units can effectively improve the peak shaving capacity of coal power units, research on the realization of start-stop peak shaving after the configuration of liquid air energy storage system for units and the configuration of energy storage capacity is still relatively scarce. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a thermal power cogeneration unit start-stop peak shaving system based on liquid air energy storage and a system minimum capacity configuration method. The thermal power cogeneration unit realizes the function of start-stop peak shaving within a day without shutdown, takes into account the task of people's livelihood and supply, and proposes a minimum capacity configuration method to minimize the initial investment.

[0006] To solve the above technical problems, the technical solutions adopted by the present application are as follows.

[0007] The peak shaving system of the combined heat and power unit based on liquid air energy storage includes a coal-fired unit power generation unit for producing electric energy, a liquid air energy storage unit 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, and a civil heating unit for external heating by using the heating extraction steam provided by the coal-fired unit power generation unit and the excess compressed heat provided by the liquid air energy storage unit. The high-pressure 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 heating unit is connected to the liquid air energy storage unit and the coal-fired unit power generation unit respectively. The civil heating unit is connected to a heating pipe network.

[0008] Further optimization of the technical scheme, the coal-fired unit power generation unit includes a boiler and a steam turbine high-pressure cylinder, a steam turbine medium-pressure cylinder, a steam turbine low-pressure cylinder and a coal-fired generator connected in series 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 steam end of the civil heating unit is connected to the exhaust end of the steam turbine medium-pressure cylinder.

[0009] Further optimization of the technical scheme, the civil heating unit includes a subcooler and a compression heat heater and a heat network heater connected in parallel and then connected in series with the subcooler. The heat network heater is connected to the coal-fired unit power generation unit to form a first heating cycle, and the compression heat heater is connected to the subcooler and the liquid air energy storage unit to form a second heating cycle. The compression heat heater and the heat network heater are connected to the heating pipe network respectively.

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

[0011] Further optimization of the technical scheme, the storage module includes a first compressor and a second compressor connected in series. The first compressor and the second compressor are connected to the energy storage transformer through a first compressor drive motor and a second compressor drive motor respectively. The rear end of the first compressor and the second compressor is provided with a first compressor rear cooler and a second compressor rear cooler respectively. The heat exchange end of the first compressor rear cooler is connected to a heat storage device. The rear of the second compressor rear cooler is provided with a liquefaction main heat exchanger. The heat exchange end of the liquefaction main heat exchanger is connected to a cold storage device. The rear end of the liquefaction main heat exchanger is provided with a liquid air storage tank for storing liquid air.

[0012] Further optimize the technical scheme, the power generation module comprises a low-temperature pressurizing pump, a gasifier, a reheater and an air expander connected in sequence behind the liquid air storage tank, the heat exchange end of the gasifier is connected with the cold storage end of the cold storage device, the heat exchange end of the reheater is connected with the heat storage end of the heat storage device, and the air expander is connected with the energy storage transformer through the energy storage generator.

[0013] The minimum capacity configuration method of the combined heat and power unit start-stop peak shaving system based on liquid air energy storage is realized based on the combined heat and power unit start-stop peak shaving system, and comprises the following steps:

[0014] S1. Determine the instantaneous maximum heat load demand Q of the external network and the heat supply characteristic curve of the combined heat and power unit;

[0015] S2. Determine the minimum electric load P1 corresponding to the heating steam extraction amount of the combined heat and power unit under the condition of the heat load Q;

[0016] S3. Assume that the actual operation electric load initial value P2 of the combined heat and power unit, wherein P2

[0017] S4. Determine the heat supply gap B1 of the combined heat and power unit and the charging power A1 of the liquid air energy storage system;

[0018] S5. Determine the capacity C and system parameters of the liquid air energy storage system according to the charging power of the liquid air energy storage system, and calculate the surplus compression heat in the system, and the compression heat provides heat for the civil heating unit to supply heat, and the heat supply amount is B2;

[0019] S6. Calculate the deviation between the surplus compression heat supply amount B2 and the heat supply gap B1 of the combined heat and power unit , and the calculation formula is:

[0020] ;

[0021] S7. According to the calculation result in S6, complete the minimum capacity of the liquid air energy storage required to realize the start-stop peak shaving function of the combined heat and power unit under the condition of meeting the heat supply demand or return the modified parameters.

[0022] Further optimize the technical scheme, in the step S1, according to the heating area K of the external network and the heating heat index q, determine the instantaneous maximum heat supply load demand Q, wherein Q=Kq; and according to the heat supply characteristic test results and the actual operation situation of the combined heat and power unit, determine the maximum heating steam extraction amount D curve corresponding to different electric loads P x under different electric loads P x , and determine the function relationship between them, wherein D=f (P ).

[0023] Further optimize the technical scheme, in the step S4, according to the electric load P2, the relationship curve of different electric load and steam extraction amount in the step S1 is combined to determine the maximum heat supply Q1 provided by the combined heat and power unit under the electric load P2 condition, and compared with the instantaneous maximum heat supply load demand Q in the step S1, the heat supply gap B1 is obtained, wherein B1=Q-Q1;

[0024] Under the electric load P2 condition, the electric load A1 needed to be consumed by the liquid air energy storage system under the condition that the combined heat and power unit on-grid load is zero is calculated, A1=P2-P t t Wherein, P t Is the sum of the production plant power and non-production plant power load of the combined heat and power unit, and A1 is the charging power of the liquid air energy storage system.

[0025] Further optimize the technical scheme, in the step S7, when the calculation result in the step S6 is The result converges, the flow is ended, and the capacity C of the liquid air energy storage system and system parameters in the step S5 are the minimum capacity of the liquid air energy storage system needed to be configured to realize the start-stop peak shaving function of the combined heat and power unit under the condition of meeting the heat supply demand.

[0026] When the calculation result in the step S6 is The result does not converge, returns to the step S3, and the initial value P2 of the assumed unit actual operation electric load is modified, the setting initial value of P2 is modified, that is, the initial value is increased until the convergent result is met, and the flow is ended.

[0027] Due to the adoption of the above technical scheme, the technical progress achieved by the application is as follows.

[0028] The combined heat and power unit start-stop peak shaving system based on liquid air energy storage and the minimum capacity configuration method of the system provided by the application make the unit reduce the on-grid power to zero without shutdown, realize the start-stop peak shaving function, and propose the minimum capacity configuration method of the liquid air energy storage for realizing the start-stop peak shaving on the basis of guaranteeing the maximum heat supply load of the external grid according to the actual heat supply characteristic curve of the unit, which can guarantee heat supply and realize the start-stop peak shaving function, and reduce the system redundancy and initial investment with the minimum capacity configuration. DETAILED DESCRIPTION

[0029] Figure 1 It is a structural schematic diagram of the application;

[0030] Figure 2 It is a flow chart of the minimum capacity configuration method of the liquid air energy storage in the application;

[0031] Figure 3The heat supply load characteristic test of the unit in the embodiment of the present application and the heat supply characteristic curve determined by combining the steam extraction working condition diagram.

[0032] Wherein: 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 after-cooler, 106. Second compressor after-cooler, 107. Main liquefied heat exchanger, 108. Liquid air storage tank, 109. Low-temperature pressurizing pump, 110. Vaporizer, 111. Cold storage device, 112. Reheater, 113. Heat storage device, 114. Air expander, 115. Energy storage generator, 116. Energy storage transformer;

[0033] 200. Civil heat supply unit, 201. Subcooler, 202. Compression heat heater, 203. Heat network heater;

[0034] 300. Coal-fired unit power generation unit, 301. Boiler, 302. High-pressure cylinder of steam turbine, 303. Medium-pressure cylinder of steam turbine, 304. Low-pressure cylinder of steam turbine, 305. Coal-fired generator. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0036] The coal-fired unit power generation unit 300 is used for normal production of electric energy and provides heating steam extraction for the civil heat supply unit 200; the liquid air energy storage unit 100 is used for consumption of coal-fired unit electric load, converts electric energy into heat and liquid air storage, thereby consuming electric energy of the coal-fired unit power generation unit 300 during the start-stop peak shaving period of the coal-fired unit, reducing the on-grid electric quantity of the unit to zero, achieving external start-stop peak shaving without shutdown of the unit, and supplying the civil heat supply unit 200 with the surplus compression heat during the energy storage process, releasing energy during the peak period of the coal-fired unit power generation unit 300, using the liquid air to increase pressure and temperature and expand to generate electricity, and jointly on-grid with the electric quantity generated by the coal-fired unit; the civil heat supply unit 200 supplies external heat by using the heating steam extraction provided by the coal-fired unit power generation unit 300 and the surplus compression heat provided by the liquid air energy storage unit 100. Figure 1 As shown in the figure, it comprises a coal-fired unit power generation unit 300, a liquid air energy storage unit 100 and a civil heat supply unit 200, the high-pressure equipment of the liquid air energy storage unit 100 is connected to the power generation end of the coal-fired unit power generation unit 300, the civil heat supply unit 200 is connected to the liquid air energy storage unit 100 and the coal-fired unit power generation unit 300 respectively, and the civil heat supply unit 200 is connected to the heat supply pipe network.

[0037] The coal-fired unit power generation unit 300 is used for normal production of electric energy and provides heating steam extraction for the civil heat supply unit 200; the liquid air energy storage unit 100 is used for consumption of coal-fired unit electric load, converts electric energy into heat and liquid air storage, thereby consuming electric energy of the coal-fired unit power generation unit 300 during the start-stop peak shaving period of the coal-fired unit, reducing the on-grid electric quantity of the unit to zero, achieving external start-stop peak shaving without shutdown of the unit, and supplying the civil heat supply unit 200 with the surplus compression heat during the energy storage process, releasing energy during the peak period of the coal-fired unit power generation unit 300, using the liquid air to increase pressure and temperature and expand to generate electricity, and jointly on-grid with the electric quantity generated by the coal-fired unit; the civil heat supply unit 200 supplies external heat by using the heating steam extraction provided by the coal-fired unit power generation unit 300 and the surplus compression heat provided by the liquid air energy storage unit 100.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The electricity storage module includes the first compressor 101 and the 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 driving motor 102 and the second compressor driving motor 104 respectively, the first compressor 101 and the second compressor 103 are provided with the first compressor after-cooler 105 for cooling the exhaust gas of the first compressor 101, and the first compressor after-cooler 105 is connected with the heat storage end of the heat storage device 113. The rear of the second compressor 103 is provided with the second compressor after-cooler 106 for cooling the exhaust gas of the second compressor 103, and is connected with the civil heating unit 200, and the part of the compression heat is used for civil heating. The rear of the second compressor after-cooler 106 is provided with the liquefaction main heat exchanger 107, wherein the cold release end of the cold storage device 111 is connected with the liquefaction main heat exchanger 107, for cooling and liquefying the air out of the second compressor after-cooler 107 and storing it in the liquid air storage tank 108 in the form of low-pressure liquid.

[0042] The number of compressors in the electricity 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 high-quality compression heat in the heat storage device 113 is used for power generation process, and the low-temperature surplus compression heat provides heat for the civil heating unit 200. In the embodiment, the exhaust temperature of the first compressor 101 is higher than that of the second compressor 103, and the compression heat of the second compressor 103 is surplus, and the number of compressors, the number of compression stages, and the connection mode are not limited to the mode mentioned in the embodiment.

[0043] The power generation module includes the low-temperature pressurizing pump 109, the gasifier 110, the reheater 112 and the air expander 114 connected in sequence behind the liquid air storage tank 108, so that the liquid air in the liquid air storage tank 108 is pressurized by the low-temperature pressurizing pump 109 and then enters the gasifier 110 to become high-pressure gaseous air, the cold storage end of the cold storage device 111 is connected with the gasifier 110, for storing the cold energy when the liquid air is gasified, and releasing the cold energy during the electricity 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 with the heat release end of the heat storage device 113, the air expander 114 is connected with the energy storage generator 115 and the energy storage transformer 116, the electricity generated by the air expander 114 dragging the energy storage generator 115 is fed into the energy storage transformer 116, and the electricity generated by the coal-fired unit power generation unit 300 is fed into the grid.

[0044] The minimum capacity configuration method of the start-stop peak regulation system of the combined heat and power unit based on liquid air energy storage is realized based on the combined heat and power unit based on liquid air energy storage, and a flow chart is as shown in Figure 2 The minimum capacity configuration method of the start-stop peak regulation system of the combined heat and power unit based on liquid air energy storage is realized based on the combined heat and power unit based on liquid air energy storage, and a flow chart is as shown in

[0045] S1. Determine the instantaneous maximum heat load demand Q of the external network and the heating characteristic curve of the cogeneration unit.

[0046] 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 ).

[0047] 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.

[0048] 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.

[0049] S3. Assume that the initial value of the actual operating electrical load of the cogeneration unit is P2, where P2 < P1.

[0050] S4. Determine the heating gap B1 of the cogeneration unit and the charging power A1 of the liquid air energy storage system.

[0051] 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.

[0052] 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 Let A1 be the sum of the electricity loads of the cogeneration unit for both production and non-production plant use, then A1 is the charging power of the liquid air energy storage system.

[0053] 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.

[0054] 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:

[0055] .

[0056] S7. According to the calculation result in S6, the minimum capacity of the liquid air energy storage required to be configured for realizing the start-stop peak shaving function of the cogeneration unit under the condition of meeting the heat supply demand or the modified parameter is returned.

[0057] When the calculation result in step S6 is , the result converges, the process ends, and the capacity C and the system parameter of the liquid air energy storage system in step S5 are the minimum capacity of the liquid air energy storage required to be configured for realizing the start-stop peak shaving function of the cogeneration unit under the condition of meeting the heat supply demand;

[0058] When the calculation result in step S6 is , the result does not converge, and the process returns to step S3, in which the initial value P2 of the actual operation electric load of the assumed unit is modified. The set initial value of the modification of P2 means that the initial value is increased until the convergent result is met, and the process ends.

[0059] The implementation effect of the present application is described below with specific embodiments.

[0060] A No. 1 unit of a power plant is a 330 MW subcritical, steam extraction heat supply, wet condensing steam turbine. The steam extraction of the fifth stage of the steam turbine is used as the steam source for civil heating, and the rated extraction pressure is 0.43 MPa, and the rated extraction amount is 550 t / h.

[0061] Taking the heating area of the unit as 6 million m 2 , 7 million m 2 , 8 million m 2 and the heating index of 42 W / m 2 , respectively, the heat supply characteristic curve determined according to the unit heat supply load characteristic test and combined with the extraction working condition diagram is shown in Figure 3 . In the diagram, the BC line is the minimum electric load curve corresponding to different extraction amounts, and the storage and release time of the liquid air energy storage system can be determined according to the start-stop peak shaving requirement and the time length of the power peak and valley section. In this embodiment, the zero on-grid electric quantity of the coal-fired unit is maintained for 6 h, and the power generation time is 5-6 h. According to the method described in the present application, the minimum capacity calculation data of the liquid air energy storage required to be configured for realizing the start-stop peak shaving function under the condition of meeting the unit heat supply are shown in Table 1.

[0062]

Claims

1. A method for configuring the minimum capacity of a start-up and peak-shaving system for a combined heat and power (CHP) unit based on liquid air energy storage, characterized in that: The minimum capacity configuration method is applied to the start-up, shutdown, and peak-shaving system of a combined heat and power unit with liquid air energy storage. The combined heat and power (CHP) unit start-stop peak shaving system 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 it into heat and liquid air for storage, and a domestic heating unit (200) for supplying external heat 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-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), and the domestic heating unit (200) is connected to both the liquid air energy storage unit (100) and the coal-fired power generation unit (300). The domestic heating unit (200) is connected to the heating network. The minimum capacity configuration method for start-up and peak-shaving systems of cogeneration units based on liquid air energy storage specifically 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.

2. The minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration 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 minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration 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 minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration 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 minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration 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 minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration 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. The minimum capacity configuration method for the start-up and shutdown peak-shaving system of a cogeneration unit based on liquid air energy storage according to claim 1, 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 ).

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 according to claim 1, 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 Let A1 be the sum of the electricity loads of the cogeneration unit for both production and non-production plant use, then A1 is the charging power of the liquid air energy storage system.

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 according to claim 1, 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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