Poly-generation system and control method thereof

Abstract

The invention provides a poly-generation system and a control method thereof. The system mainly comprises an air purification system, an air compression system, a liquid air production system, a liquid air phase change system, an energy storage system, an air separation system, a power generation system, a refrigeration system and a heat supply system. Wherein the air purification system is connected with the air compression system, and the air compression system is connected with the liquid air production system. The liquid-air production system is connected with the liquid-air phase change system, and the liquid-air phase change system is connected with the energy storage system; the energy storage system is further connected with a power generation system which is connected with the refrigerating system and the heat supply system. And the air separation system is connected with each system capable of supplying air. By introducing the liquid-air production system and the liquid-air phase change system and combining the application of other systems, efficient circulation of energy between the systems can be realized by utilizing the polymorphic form of air, so that not only is the comprehensive energy efficiency improved and the energy grade improved on the whole, but also products of the poly-generation system are enriched, and the flexibility of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy recycling, and in particular to a polygeneration system and a control method thereof. Background Art

[0002] Nowadays, energy forms are diversified. Although traditional energy forms still occupy an important position and are widely used in various fields such as industrial production, transportation and residents' lives, the use of traditional energy has also brought many problems, such as the gradual depletion of resources and environmental pollution.

[0003] For this reason, the development of new energy sources has received increasing attention. New energy sources include solar energy, wind energy, hydropower, biomass energy, etc., which have the advantages of being renewable and pollution-free. They have now achieved grid-connected power generation and have a tendency to gradually replace traditional energy sources. However, the energy output of renewable energy sources has obvious volatility and intermittency. For example, solar energy depends on sunshine and can only generate electricity when there is sunlight during the day, and the power generation efficiency is affected by factors such as weather, season and geographical location; wind energy depends on the size and stability of wind power. When the wind power is unstable, the power generation will fluctuate greatly. The power supply volatility mentioned above makes renewable energy sources affect the stability and reliability of the power grid when they are connected to the power grid.

[0004] In order to solve the problem of grid volatility faced by the combined use of traditional energy forms and new energy sources, the polygeneration system was proposed and put into market application. At present, the widely used polygeneration system is an integrated energy system that organically combines multiple energy production and conversion technologies to achieve the coordinated production of multiple energy products. Generally speaking, the polygeneration system includes multiple subsystems, and the subsystems work together to achieve the production and supply of multiple energy products such as cold, heat, electricity, and gas by processing and converting raw materials such as air. The polygeneration system can integrate multiple energy production and conversion processes to achieve efficient energy utilization and coordinated production of multiple energy products. It has the following important advantages:

[0005] 1. Improve energy efficiency: By coupling different energy production processes together, various energy forms in the energy conversion process, such as heat energy, cold energy, etc., can be fully utilized to reduce energy waste and improve the overall energy conversion efficiency;

[0006] 2. Reduce environmental pollution: The polygeneration system can optimize the energy structure, reduce the emission of polluting gases and the generation of other pollutants, and is environmentally friendly;

[0007] 3. Dealing with the volatility of new energy: The polygeneration system can be used as a buffer and regulation method for the access of new energy to the power grid. For example, when there is an excess of new energy generation, the excess energy can be stored and converted into other forms of energy products. When there is insufficient new energy generation, the stored energy can be released to supplement the energy supply, thereby improving the grid's acceptance and stability of new energy.

[0008] 4. Meet multiple energy needs: The polygeneration system can simultaneously produce multiple energy products such as cold, heat, electricity, and gas to meet the energy needs of different users in different scenarios and improve the flexibility and reliability of energy supply.

[0009] Although the polygeneration system has many advantages, there are still some problems in the existing polygeneration system. For example, the existing polygeneration system generally relies on a certain existing process flow, and then couples one or several other process flows to achieve the function of reusing surplus energy and producing a variety of products. In this case, there are often disadvantages such as low energy quality, poor flexibility, and the coupled process flow cannot fully exert its energy efficiency.

[0010] In summary, further improvements are needed to address the problems of low energy grade and poor coupling effect of the existing polygeneration coupling system in order to improve the overall energy utilization efficiency and expand the flexibility of the system. Summary of the invention

[0011] In view of the problems existing in the prior art, the present invention provides a polygeneration system and a supporting control method for recycling low-grade energy and producing a variety of output products.

[0012] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0013] In one aspect, the present invention provides a polygeneration system, wherein the power input end of the polygeneration system is connected to a renewable energy power supply system or a power grid;

[0014] The polygeneration system includes an air purification system, an air compression system, a liquid air production system, a liquid air phase change system, an energy storage system, an air separation system, a power generation system, a refrigeration system and a heating system;

[0015] The outlet of the air purification system is connected to the air compression system;

[0016] The air compression system is connected to the liquid air production system; the liquid air production system is connected to the liquid air phase change system, and the liquid air phase change system is connected to the energy storage system;

[0017] The energy storage system is also connected to the power generation system, and the power generation system is sequentially or separately connected to the refrigeration system and the heating system;

[0018] The air separation system is respectively connected to the air purification system, the liquid air production system, and the power generation system.

[0019] Optionally, the liquid-air phase change system includes a liquid air storage tank, a cryogenic pump and a liquid air evaporator;

[0020] The liquid air storage tank is connected to the liquid air evaporator, and the cryogenic pump is provided on at least part of the pipeline;

[0021] The liquid air production system comprises a cold box, a cryogenic expander and a gas-liquid separation tank;

[0022] The outlet of the cold box is connected to the inlet of the low-temperature expander; the outlet of the low-temperature expander is connected to the inlet of the gas-liquid separation tank.

[0023] Optionally, the energy storage system includes a heat storage subsystem and a cold storage subsystem;

[0024] The inlet end of the heat storage subsystem is respectively connected to the air purification system, the air compression system and the heating system, and the outlet end is respectively connected to the air compression system and the power generation system;

[0025] The inlet end of the cold storage subsystem is connected to the liquid-air phase change system, and the outlet end is connected to the liquid-air production system.

[0026] Optionally, the heat storage subsystem includes a metal-based heat storage tank, a circulating fan and a control valve;

[0027] The metal-based heat storage tank is connected to the circulating fan, and the control valve is provided on at least part of the pipeline;

[0028] The cold storage subsystem includes a cryogenic packed bed cold storage tank, a cold storage circulation fan and a control valve;

[0029] The deep cold packed bed cold storage tank is connected to the cold storage circulation fan, and the control valve is provided on at least part of the pipeline.

[0030] Optionally, the power generation system includes an air expansion power generation subsystem and an organic Rankine cycle power generation subsystem;

[0031] The inlet end of the air expansion power generation subsystem is respectively connected to the liquid-air phase change system and the heat storage subsystem, and the outlet end is respectively connected to the air purification system and the organic Rankine cycle power generation subsystem.

[0032] Optionally, the air expansion power generation subsystem includes at least two sets of cascaded expanders and corresponding interstage reheaters.

[0033] Optionally, the organic Rankine cycle power generation subsystem includes a heater, an expander, a preheater, a condenser, and a working fluid pump;

[0034] The outlet of the working fluid pump is connected to the inlet of the preheater, the outlet of the preheater is connected to the inlet of the heater, the outlet of the heater is connected to the inlet of the expander, the outlet of the expander is connected to the inlet of the condenser, and the outlet of the condenser is connected to the inlet of the working fluid pump.

[0035] Optionally, the refrigeration system is an absorption refrigeration system; the heating system is a heat exchange heating system;

[0036] The refrigeration system comprises a heater, a separation tank, a throttle valve, an evaporator, a mixer, a working fluid pump, and a preheater; the outlet of the working fluid pump is connected to the inlet of the preheater; the outlet of the preheater is connected to the inlet of the heater, and the outlet of the heater is connected to the inlet of the separation tank; the outlet of the separation tank is connected to the throttle valve and the mixer respectively; the outlet of the throttle valve is connected to the inlet of the evaporator, the outlet of the evaporator is connected to the inlet of the mixer, and the outlet of the mixer is connected to the inlet of the working fluid pump;

[0037] The inlet end of the refrigeration system is connected to the organic Rankine cycle power generation subsystem, and the outlet end is connected to the heating system.

[0038] Optionally, the air separation system is also preceded by an air separation feed buffer system;

[0039] The air separation feed buffer system is provided with a buffer tank and a regulating valve arranged on the pipeline;

[0040] The air separation system comprises an air separation compressor, a cooler, an air separation main heat exchanger, an air separation tower, a subcooler, a liquid oxygen pump and a classified gas storage tank; the classified gas storage tank is provided with a nitrogen storage tank, a first oxygen storage tank, and a second oxygen storage tank, and the oxygen concentration stored in the first oxygen storage tank is greater than the oxygen concentration stored in the second oxygen storage tank;

[0041] The outlets of the air separation compressor and the cooler are connected to the inlet of the air separation main heat exchanger; the outlet of the air separation main heat exchanger is connected to the inlet of the air separation tower;

[0042] The liquid phase outlet of the air separation tower is connected to the inlet of the subcooler, the outlet of the subcooler is connected to the first oxygen storage tank or the second oxygen storage tank, and the liquid oxygen pump is installed on the pipeline;

[0043] The gas phase outlet of the air separation tower is connected to the nitrogen storage tank.

[0044] On the other hand, the present invention also provides a control method based on the aforementioned polygeneration system, which comprises the following steps:

[0045] During off-peak hours;

[0046] External power is input into the polygeneration system, and the air is compressed to a high temperature and high pressure state through the air purification system and the air compression system to obtain high-pressure normal temperature air, which is then passed into the energy storage system for heat exchange;

[0047] The high-pressure normal-temperature air after heat exchange is then subjected to low-temperature expansion cooling in a liquid air production system, and after being reduced to normal pressure, gas-liquid mixed air is obtained; the gas-liquid mixed air is separated to produce normal-pressure liquid air and low-temperature gaseous air;

[0048] The atmospheric pressure liquid air is stored in the liquid air phase change system for use in the power generation process; the low temperature gaseous air enters the liquid air production system for cooling, and is then introduced into the air separation system as raw gas;

[0049] The air separation system produces an air separation product based on the feed gas;

[0050] During peak power hours;

[0051] The normal-pressure liquid air is first cooled to a normal-temperature state by the liquid-air phase change system to obtain normal-temperature high-pressure air, and the released cold energy is exchanged for heat to be stored in the energy storage system;

[0052] The normal temperature and high pressure air is heated up after heat exchange in the energy storage system, and then introduced into the power generation system to generate power; the air after power generation is input into the air separation system as the raw gas for producing air separation products;

[0053] The recovered waste heat is input into the power generation system, refrigeration system and heating system in sequence or in a split flow.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention introduces a liquid air production system and a liquid air phase change system, and combines the application of an energy storage system, an air separation system, a power generation system, a refrigeration system, and a heating system. It can utilize the polymorphic forms of air to achieve efficient energy flow between systems. Overall, it not only improves the overall energy efficiency and energy quality, but also enriches the products of the polygeneration system and increases the flexibility of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0057] Figure 1 It is a system diagram in a specific embodiment of the present invention.

[0058] In the figure: 1. Air purification system; 2. Air compression system; 3. Liquid air production system; 4. Liquid air phase change system; 5. Air expansion subsystem; 6. Heat storage subsystem; 7. Cold storage subsystem; 8. Air separation buffer system; 9. Air separation system; 10. Organic Rankine cycle subsystem; 11. Refrigeration system; 12. Heating system. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0061] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] It is worth noting that the methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products, and their sources are not specifically limited unless otherwise specified.

[0063] like Figure 1 As shown, this embodiment provides a polygeneration system, which mainly includes an air purification system 1, an air compression system 2, a liquid air production system 3, a liquid air phase change system 4, an energy storage system, an air separation system 9, a power generation system, a refrigeration system 11 and a heating system 12.

[0064] Among them, the power input end of the air purification system 1 is connected to the renewable energy power supply system or the power grid, and the gas output end is connected to the air compression system 2; optionally, the air purification system 1 serves as the main input end of the system working fluid, and the air needs to be pre-treated to meet the required standards. Therefore, it includes an air compressor, a cooler and a molecular sieve purifier. The external air is first pressurized by the air compressor, then cooled in the cooler, and purified by the molecular sieve purifier to be used as a carrier for energy flow in subsequent systems or to directly produce products.

[0065] The air compression system 2 includes at least two sets of compressors, which are connected in cascade mode, and an interstage cooler is arranged between the stages. The air compression system 2 is connected to the liquid air production system 3; optionally, the liquid air production system 3 includes a cold box, a cryogenic expander and a gas-liquid separation tank; the cold box is connected to the cryogenic expander and the gas-liquid separation tank in sequence through pipelines. The liquid air production system 3 is connected to the liquid air phase change system 4.

[0066] Optionally, the liquid-air phase change system 4 includes a liquid air storage tank, a cryogenic pump and a liquid air evaporator; the liquid air storage tank is connected to the liquid air evaporator through a pipeline, and a cryogenic pump is also provided on the connecting pipeline.

[0067] Furthermore, in this embodiment, the energy storage system also includes two subsystems, which are used for cold storage and heat storage, respectively, specifically including a heat storage subsystem 6 and a cold storage subsystem 7 .

[0068] The heat storage subsystem 6 is a metal-based heat storage system, which includes a metal-based heat storage tank, a circulating fan and a control valve. The metal-based heat storage tank is connected to the circulating fan, and a control valve is provided on the connecting pipeline. The inlet end of the heat storage subsystem 6 is respectively connected to the air purification system 1, the air compression system 2 and the heating system 12, and the outlet end is respectively connected to the air compression system 2 and the power generation system.

[0069] The cold storage subsystem 7 includes a cryogenic packed bed cold storage tank, a cold storage circulation fan and a control valve. The cryogenic packed bed cold storage tank is connected to the cold storage circulation fan, and a control valve is also provided on the connecting pipeline. The inlet end of the cold storage subsystem 7 is connected to the liquid-air phase change system 4, and the outlet end is connected to the liquid-air production system 3.

[0070] Optionally, in this embodiment, the power generation system is also composed of two subsystems to efficiently utilize energy, which specifically includes an air expansion power generation subsystem 5 and an organic Rankine cycle power generation subsystem 10; the air expansion power generation subsystem 5 is upstream of the organic Rankine cycle power generation subsystem 10, preferentially receives high-quality thermal energy from the heat storage subsystem 6, and transfers the low-quality thermal energy after heat release into the organic Rankine cycle power generation subsystem 10 for reuse. Thus, the inlet end of the air expansion power generation subsystem 5 is respectively connected to the liquid-air phase change system 4 and the heat storage subsystem 6, and the outlet end is respectively connected to the air purification system 1 and the organic Rankine cycle power generation subsystem 10. Further, the air expansion power generation subsystem 5 includes at least two sets of cascaded expanders and corresponding interstage reheaters.

[0071] Optionally, the organic Rankine cycle power generation subsystem 10 includes a heater, an expander, a preheater, a condenser and a working fluid pump. The outlet of the working fluid pump is connected to the inlet of the preheater, the outlet of the preheater is connected to the inlet of the heater, the outlet of the heater is connected to the inlet of the expander, the outlet of the expander is connected to the inlet of the condenser, and the outlet of the condenser is connected to the inlet of the working fluid pump, thereby forming a complete cycle for extracting the remaining energy of the working fluid.

[0072] In this embodiment, the organic Rankine cycle power generation subsystem 10 transmits surplus energy to the refrigeration system 11 through a circulation pipeline. The refrigeration system 11 is an absorption refrigeration system, which mainly includes a heater, a separation tank, a throttle valve, an evaporator, a mixer, a working fluid pump, and a preheater; the outlet of the working fluid pump is connected to the inlet of the preheater; the outlet of the preheater is connected to the inlet of the heater, and the outlet of the heater is connected to the inlet of the separation tank; the outlet of the separation tank is connected to the throttle valve and the mixer respectively; the outlet of the throttle valve is connected to the inlet of the evaporator, the outlet of the evaporator is connected to the inlet of the mixer, and the outlet of the mixer is connected to the inlet of the working fluid pump;

[0073] The outlet of the refrigeration system 11 is connected to the heating system 12, and heat is transferred to the heating system 12 by heat exchange. The heating system 12 is a heat exchange heating system, and its main body is a heating heat exchanger.

[0074] The air separation system 9 is respectively connected to the air purification system 1, the liquid air production system 3 and the air expansion and power generation subsystem 5 in the power generation system. Optionally, in order to enable the raw gas to be mixed before entering the air separation system 9, a relatively constant air composition ratio and feed flow rate are provided to ensure the stable operation of the air separation system, the present embodiment is also provided with an air separation feed buffer system 8 before the air separation system 9, which is provided with a buffer tank and a regulating valve arranged on the pipeline, and the raw gas provided by other systems or subsystems must first be fully mixed in the buffer tank under controllable conditions before entering the air separation system 9 for production.

[0075] Optionally, the air separation system 9 includes an air separation compressor, a cooler, an air separation main heat exchanger, an air separation tower, a subcooler, a liquid oxygen pump and a classified gas storage tank. The classified gas storage tank is a storage container for air products, generally provided with a nitrogen storage tank, a first oxygen storage tank and a second oxygen storage tank, and the first oxygen storage tank is mainly a pure oxygen storage tank, and the second oxygen storage tank is mainly a high-concentration oxygen storage tank.

[0076] Specifically, the outlet of the air separation compressor and the cooler is connected to the inlet of the air separation main heat exchanger; the outlet of the air separation main heat exchanger is connected to the inlet of the air separation tower; the liquid phase outlet of the air separation tower is connected to the inlet of the subcooler, the outlet of the subcooler is connected to the first oxygen storage tank or the second oxygen storage tank, and a liquid oxygen pump is installed on the pipeline. The gas phase outlet of the air separation tower is connected to the nitrogen storage tank.

[0077] The polygeneration system provided in this embodiment realizes the supply of high-quality cold, heat, electricity, and gas products or energy by introducing liquid air energy storage technology. The buffer tank and control valve ensure the relative stability of the composition of the raw gas flow of the air separation system, so that the air separation system can operate stably for 24 hours; by introducing the metal-based heat storage system, a large amount of heat energy in the compression process will not be wasted; by introducing the organic Rankine cycle, absorption refrigeration and heat supply heat exchanger, the surplus heat energy can be fully utilized; by introducing the cold storage subsystem using a deep cold packed bed, the cold energy in the air liquefaction process can be self-sufficient in the system internal circulation. Therefore, at the system level, the energy generated during the operation of the raw materials and the system is fully and effectively utilized, the product quality is reasonably distributed, and the system energy utilization rate and system efficiency are improved; at the income level, the introduction of the air separation system, the organic Rankine cycle subsystem, the absorption refrigeration system and the heat supply subsystem increases the income items of the system, and multiple products such as electricity, high-quality heat, high-purity gas, low-quality heat, and cold energy can be supplied at the same time, which improves the overall income and reduces the loss caused by energy fluctuations.

[0078] This embodiment further provides a supporting control method based on the above-mentioned polygeneration system, which includes the following steps:

[0079] During off-peak hours;

[0080] Surplus external renewable energy or grid off-peak electricity is input into the polygeneration system, and the air is compressed to a high-temperature and high-pressure state through the air purification system 1 and the air compression system 2 to obtain high-pressure room-temperature air, which is then passed into the metal-based heat storage tank in the heat storage subsystem 6 to exchange heat with the metal-based material, wherein the heat energy is thereby stored in the metal-based heat storage tank.

[0081] The high-pressure normal-temperature air after heat exchange is then deeply cooled by the cold box in the liquid air production system 3, and then reduced to normal pressure by the low-temperature expander to become a gas-liquid mixture, and then separated into normal-pressure liquid air and low-temperature gaseous air by the gas-liquid separation tank.

[0082] Normal pressure liquid air is stored in the liquid air storage tank in the liquid air phase change system 4 for use in the subsequent power generation process; low temperature gaseous air enters the cold box in the liquid air production system 3 for cooling, and is then introduced into the buffer tank of the air separation buffer system 8 to serve as part of the raw gas for the air separation system 9.

[0083] The air separation system 9 produces air separation products based on the feed gas provided by various systems and subsystems.

[0084] During peak power hours;

[0085] The normal pressure liquid air stored in the liquid air storage tank first enters the liquid air phase change system 4, is pressurized in the cryogenic pump, and then evaporates and cools to room temperature in the liquid air evaporator. The released cold energy is absorbed by the cold storage circulating working fluid of the cold storage subsystem 7 and stored in the deep cold packed bed storage tank. The stored cold energy will provide cold for the cold box during the valley power period, realizing the self-sufficiency of the system cold energy. The liquid air is cooled to room temperature to obtain room temperature high pressure air.

[0086] The room temperature and high pressure air is heated up after heat exchange in the heat storage subsystem 6, and then is introduced into the air expansion and power generation subsystem 5, where it is depressurized and works in the expander to release electrical energy.

[0087] The surplus heat energy of the heat storage subsystem 6 first enters the heater of the organic Rankine cycle power generation subsystem 10 through heat exchange, heating the working fluid to turn it into a superheated vapor state, and then the low-grade heat energy after cooling enters the heater of the refrigeration system 11, heating the working fluid to turn it into a gas-liquid mixture, and then the low-grade heat energy after further cooling enters the heat exchanger of the heating system 12, heating it to increase its temperature, and finally returns to the low-temperature heat storage tank to wait for the next cycle.

[0088] After power generation, the air is input into the buffer tank of the air separation buffer system 8 to serve as part of the feed gas of the air separation system 9 for producing air separation products.

[0089] Optionally, at the same time or in different time periods of the above steps, the air separation system 9 performs corresponding production according to the composition and state of the raw gas, and the steps further include:

[0090] Since the raw gas of the air separation system consists of three parts, namely, the cooled air from the gas-liquid separation tank, the air after expansion and power generation, and the conventional air supplement, the gas composition ratio, flow rate and supply time of these three parts are different, so the buffer tank and control valve can mix the raw gas before entering the air separation system, providing a relatively constant air composition ratio and feed flow rate, ensuring the stable operation of the air separation system;

[0091] During the off-peak period, the nitrogen content in the cooled air from the gas-liquid separation tank is relatively high, and the products of the air separation system 9 are pure nitrogen and high-oxygen oxygen;

[0092] During peak power generation, the oxygen content in the air after expansion and power generation is relatively high, and the products of the air separation system 9 are pure nitrogen and pure oxygen.

[0093] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A polygeneration system, characterized in that: The power input of the polygeneration system is connected to the renewable energy power supply system or the power grid; The polygeneration system includes an air purification system, an air compression system, a liquid air production system, a liquid air phase change system, an energy storage system, an air separation system, a power generation system, a refrigeration system and a heating system; The outlet of the air purification system is connected to the air compression system; The air compression system is connected to the liquid air production system; the liquid air production system is connected to the liquid air phase change system, and the liquid air phase change system is connected to the energy storage system; The energy storage system is also connected to the power generation system, and the power generation system is sequentially or separately connected to the refrigeration system and the heating system; The air separation system is respectively connected to the air purification system, the liquid air production system, and the power generation system.

2. The polygeneration system according to claim 1, characterized in that: The liquid-air phase change system comprises a liquid air storage tank, a cryogenic pump and a liquid air evaporator; The liquid air storage tank is connected to the liquid air evaporator, and the cryogenic pump is provided on at least part of the pipeline; The liquid air production system comprises a cold box, a cryogenic expander and a gas-liquid separation tank; The outlet of the cold box is connected to the inlet of the low-temperature expander; the outlet of the low-temperature expander is connected to the inlet of the gas-liquid separation tank.

3. The polygeneration system according to claim 1 or 2, characterized in that: The energy storage system includes a heat storage subsystem and a cold storage subsystem; The inlet end of the heat storage subsystem is respectively connected to the air purification system, the air compression system and the heating system, and the outlet end is respectively connected to the air compression system and the power generation system; The inlet end of the cold storage subsystem is connected to the liquid-air phase change system, and the outlet end is connected to the liquid-air production system.

4. The polygeneration system according to claim 3, characterized in that: The heat storage subsystem includes a metal-based heat storage tank, a circulating fan and a control valve; The metal-based heat storage tank is connected to the circulating fan, and the control valve is provided on at least part of the pipeline; The cold storage subsystem includes a cryogenic packed bed cold storage tank, a cold storage circulation fan and a control valve; The deep cold packed bed cold storage tank is connected to the cold storage circulation fan, and the control valve is provided on at least part of the pipeline.

5. The polygeneration system according to claim 3, characterized in that: The power generation system includes an air expansion power generation subsystem and an organic Rankine cycle power generation subsystem; The inlet end of the air expansion power generation subsystem is respectively connected to the liquid-air phase change system and the heat storage subsystem, and the outlet end is respectively connected to the air purification system and the organic Rankine cycle power generation subsystem.

6. The polygeneration system according to claim 5, characterized in that: The air expansion power generation subsystem includes at least two sets of cascaded expanders and corresponding inter-stage reheaters.

7. The polygeneration system according to claim 5, characterized in that: The organic Rankine cycle power generation subsystem includes a heater, an expander, a preheater, a condenser, and a working fluid pump; The outlet of the working fluid pump is connected to the inlet of the preheater, the outlet of the preheater is connected to the inlet of the heater, the outlet of the heater is connected to the inlet of the expander, the outlet of the expander is connected to the inlet of the condenser, and the outlet of the condenser is connected to the inlet of the working fluid pump.

8. The polygeneration system according to claim 5, characterized in that: The refrigeration system is an absorption refrigeration system; the heating system is a heat exchange heating system; The refrigeration system comprises a heater, a separation tank, a throttle valve, an evaporator, a mixer, a working fluid pump, and a preheater; the outlet of the working fluid pump is connected to the inlet of the preheater; the outlet of the preheater is connected to the inlet of the heater, and the outlet of the heater is connected to the inlet of the separation tank; the outlet of the separation tank is connected to the throttle valve and the mixer respectively; the outlet of the throttle valve is connected to the inlet of the evaporator, the outlet of the evaporator is connected to the inlet of the mixer, and the outlet of the mixer is connected to the inlet of the working fluid pump; The inlet end of the refrigeration system is connected to the organic Rankine cycle power generation subsystem, and the outlet end is connected to the heating system.

9. The polygeneration system according to claim 1, characterized in that: The air separation system is also provided with an air separation feed buffer system in front; The air separation feed buffer system is provided with a buffer tank and a regulating valve arranged on the pipeline; The air separation system comprises an air separation compressor, a cooler, an air separation main heat exchanger, an air separation tower, a subcooler, a liquid oxygen pump and a classified gas storage tank; the classified gas storage tank is provided with a nitrogen storage tank, a first oxygen storage tank, and a second oxygen storage tank, and the oxygen concentration stored in the first oxygen storage tank is greater than the oxygen concentration stored in the second oxygen storage tank; The outlets of the air separation compressor and the cooler are connected to the inlet of the air separation main heat exchanger; the outlet of the air separation main heat exchanger is connected to the inlet of the air separation tower; The liquid phase outlet of the air separation tower is connected to the inlet of the subcooler, the outlet of the subcooler is connected to the first oxygen storage tank or the second oxygen storage tank, and the liquid oxygen pump is installed on the pipeline; The gas phase outlet of the air separation tower is connected to the nitrogen storage tank.

10. A polygeneration system control method, characterized in that: The steps include: During off-peak hours; External power is input into the polygeneration system, and the air is compressed to a high temperature and high pressure state through the air purification system and the air compression system to obtain high-pressure normal temperature air, which is then passed into the energy storage system for heat exchange; The high-pressure normal-temperature air after heat exchange is then subjected to low-temperature expansion cooling in a liquid air production system, and after being reduced to normal pressure, gas-liquid mixed air is obtained; the gas-liquid mixed air is separated to produce normal-pressure liquid air and low-temperature gaseous air; The atmospheric pressure liquid air is stored in the liquid air phase change system for use in the power generation process; the low temperature gaseous air enters the liquid air production system to cool down, and then is introduced into the air separation system as raw gas; The air separation system produces an air separation product based on the feed gas; During peak power hours; The normal-pressure liquid air is first cooled to a normal-temperature state by the liquid-air phase change system to obtain normal-temperature high-pressure air, and the released cold energy is exchanged for heat to be stored in the energy storage system; The normal temperature and high pressure air is heated up after heat exchange in the energy storage system, and then introduced into the power generation system to generate power; the air after power generation is input into the air separation system as the raw gas for producing air separation products; The recovered waste heat is input into the power generation system, refrigeration system and heating system in sequence or in a split flow.

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