Cold box internal structure and liquid air energy storage power station

Abstract

The application relates to a cold box internal structure and a liquid air energy storage power station. The cold box internal structure is connected with heat exchangers in pairs in stages, at least one pair of heat exchangers is connected with an LNG cold energy utilization unit through a first LNG cold storage medium circulation loop, the air heat releasing sides of energy storage heat exchangers in each stage are connected with energy storage pipelines, the air heat absorbing sides of energy release heat exchangers are connected with energy release pipelines, the energy storage pipelines and the energy release pipelines are connected with liquid air storage tanks, the energy storage heat exchangers and the energy release heat exchangers in the same pair are connected with the same cold box circulation loop, the structure can make the air be gradually cooled and liquefied to form liquid air in the energy storage stage, and the liquid air is gradually heated and warmed in the energy release stage. The first LNG cold storage medium circulation loop introduces the cold energy of the LNG cold energy utilization unit into the heat exchanger, and the cold box circulation loop introduces the heat energy of the energy storage heat exchanger into the energy release heat exchanger, so as to provide heat energy for the air in the energy release stage. The structure can reduce the heat loss in the cold energy transmission process, improve the liquid air liquefaction rate, and realize high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a cold box internal structure for coupling LNG cold energy utilization and a liquid air energy storage power station. BACKGROUND

[0002] Due to energy structure adjustment, the current society has entered a replacement period of oil and gas replacing coal and non-fossil energy replacing fossil energy. At present, taking liquefied natural gas (LNG) as the main consideration object, since the temperature of LNG is extremely low (generally near minus 162 degrees Celsius), a large amount of cold energy is contained therein. In the traditional LNG regasification process, the LNG cold energy is not utilized but released to the environment, causing a large amount of cold energy resource to be wasted. With the popularization of natural gas, the construction speed of LNG receiving stations is accelerated, and the LNG receiving scale is gradually expanded. The available LNG cold energy resource is huge, and it has extremely important practical significance to recover this part of cold energy.

[0003] The LNG cold energy utilization modes include air separation, cold energy power generation, dry ice production, seawater desalination, cold storage and refrigeration, etc. The LNG cold energy power generation technology needs stable supply of cold energy, and other direct utilization modes of cold energy are affected by the construction scale of LNG receiving terminal and local demand. For the areas with large construction scale of LNG receiving terminal and small local cold load demand, the above LNG cold energy utilization modes are difficult to realize large-scale application. As an important part of the construction of new power system, in recent years, new energy storage technology has been vigorously promoted, and liquid air energy storage is a new large-scale long-time energy storage technology with the advantage of not being limited by geographical conditions. Therefore, if the liquid air energy storage system can be coupled with the LNG cold energy utilization, the LNG cold energy utilization and the efficiency of the liquid air energy storage system can be greatly improved, which has very good energy utilization prospect and great environmental protection significance.

[0004] However, in the existing liquid air energy storage system coupled with LNG cold energy utilization, the problem that the LNG cold energy supply time is inconsistent with the energy storage / discharging period of the energy storage system is ignored, and the cascade recovery and utilization of LNG cold energy is not sufficient, and the high-grade cold energy is not directly transferred to the air liquefaction process. Therefore, the liquid air energy storage system indirectly utilizing LNG cold energy in the conventional technology is difficult to improve the LNG cold energy utilization rate. Moreover, in the discharging process of the energy storage system, the introduction of LNG cold energy cannot decouple the energy storage process and the discharging process of the system, the cold energy of liquid air cannot be converted into pressure energy more, the power capacity cannot be greatly improved, the power generation capacity of the energy storage system is small, and the electrical-to-electrical conversion efficiency of the coupled system is not ideal. SUMMARY

[0005] The application provides a cold box internal structure and a liquid air energy storage power station, to solve the problem that the prior art fails to realize the cascade recovery of LNG cold energy, and the high-grade cold energy is not directly transmitted to the air liquefaction process.

[0006] The application provides a cold box internal structure, which comprises at least one pair of heat exchangers and at least one set of cold box circulation loops, each pair of heat exchangers is connected in cascade, and at least one pair of heat exchangers is connected to an LNG cold energy utilization unit through a primary LNG cold storage medium circulation loop; each pair of heat exchangers comprises a storage heat exchanger and a release heat exchanger, the air heat releasing side of each storage heat exchanger is connected to a storage pipeline, the air heat absorbing side of each release heat exchanger is connected to a release pipeline, and the storage pipeline and the release pipeline are both connected to a liquid air storage tank; the cold box working medium heat absorbing side of the storage heat exchanger and the cold box working medium heat releasing side of the release heat exchanger in the same pair are both connected to the same cold box cold storage medium circulation loop.

[0007] In the storage stage, the air flowing in the storage pipeline is gradually cooled and liquefied by absorbing cold energy through each storage heat exchanger, and the formed liquid air is stored in the liquid air storage tank.

[0008] In the release stage, the liquid air flowing out of the liquid air storage tank is pressurized and gradually heated by absorbing heat through each release heat exchanger.

[0009] The primary LNG cold storage medium circulation loop introduces the cold energy of the LNG cold energy utilization unit into the storage heat exchanger, and provides cold energy for the high-pressure air flowing through the storage heat exchanger.

[0010] The cold box circulation loop introduces the heat energy of the storage heat exchanger into the release heat exchanger, and provides heat energy for the high-pressure air flowing through the release pipeline.

[0011] According to the cold box internal structure, the storage pipeline is connected to the liquid air storage tank through a gas-liquid separator, the gas-liquid separator is provided with an exhaust pipeline, and the exhaust pipeline is connected to the air heat absorbing side of the storage heat exchanger.

[0012] The high-pressure air flowing in the storage pipeline is gradually cooled and liquefied by absorbing cold energy through each storage heat exchanger, and then enters the gas-liquid separator after being expanded and throttled to normal pressure, the gas-liquid separator separates the liquid air and discharges the reverse flow gas through the exhaust pipeline to release cold energy through the storage heat exchanger.

[0013] According to the cold box internal structure, the energy storage pipeline is provided with a liquid expander connected between the last-stage energy storage heat exchanger and the inlet end of the gas-liquid separator.

[0014] According to the cold box internal structure, the energy storage pipeline is provided with a throttle valve connected between the last-stage liquid expander and the inlet end of the gas-liquid separator.

[0015] According to the cold box internal structure, the primary LNG cold storage medium circulation loop comprises a temperature-increasing pipeline connected to the energy storage heat exchanger or the energy release heat exchanger and a temperature-decreasing pipeline connected to the LNG cold energy utilization unit.

[0016] According to the cold box internal structure, the at least one pair of heat exchangers comprises a pair of primary heat exchangers, and the pair of primary heat exchangers comprises a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is the energy storage heat exchanger, and the second heat exchanger is the energy release heat exchanger; the first heat exchanger is connected to the energy storage pipeline, and the second heat exchanger is connected to the energy release pipeline.

[0017] The cold box working medium heat absorption side of the first heat exchanger and the cold box working medium heat release side of the second heat exchanger are connected through a primary cold box cold storage working medium circulation loop.

[0018] According to the cold box internal structure, the at least one pair of heat exchangers further comprises a pair of secondary heat exchangers, and the pair of secondary heat exchangers comprises a third heat exchanger and a fourth heat exchanger, wherein the third heat exchanger is the energy storage heat exchanger, and the fourth heat exchanger is the energy release heat exchanger.

[0019] The energy storage pipeline is connected to the first heat exchanger and the third heat exchanger in series in stages, and the energy release pipeline is correspondingly connected to the fourth heat exchanger and the second heat exchanger in series in stages.

[0020] The cold box working medium heat absorption side of the third heat exchanger and the cold box working medium heat release side of the fourth heat exchanger are connected through a secondary cold box cold storage working medium circulation loop.

[0021] According to the cold box internal structure, the cold box internal structure further comprises an evaporator, a fifth heat exchanger and an organic working medium Rankine cycle loop, the heat source heat release side of the evaporator is connected to an external heat source, the organic working medium heat absorption side of the evaporator and the organic working medium heat release side of the fifth heat exchanger are connected through the organic working medium Rankine cycle loop; and the energy release pipeline is connected to the energy release heat exchanger and the fifth heat exchanger in series in stages.

[0022] The application also provides a liquid air energy storage power station, comprising: an LNG cold energy utilization unit; an air pretreatment unit; a cold tank body comprising the cold tank internal structure; an energy storage module comprising a plurality of connected multi-stage compressor sets, an air heat release side of the cold tank body, a liquid expander, a throttle valve, an air-liquid separator and a liquid air storage tank, an inlet end of the multi-stage compressor set being connected to the air pretreatment unit, the air pretreatment unit being connected to the LNG cold energy utilization unit through a two-stage LNG cold storage medium circulation loop, the multi-stage compressor set and the air heat release side of the cold tank body being connected to the LNG cold energy utilization unit through a one-stage LNG cold storage medium circulation loop respectively; and an energy release module comprising a plurality of connected multi-stage air expanders, the liquid air storage tank being connected to the multi-stage air expanders through an air heat absorption side of the cold tank internal structure.

[0023] According to the liquid air energy storage power station, the air pretreatment unit comprises an air filter, a molecular sieve purifier, an air pre-cooler and an air super-cooler, the air filter, the molecular sieve purifier, the air pre-cooler, the air super-cooler and the multi-stage compressor set are sequentially connected in series to the energy storage pipeline; the LNG cold energy utilization unit comprises an LNG vaporizer and a natural gas superheater connected in series; the air pre-cooler is connected to the natural gas superheater through the two-stage LNG cold storage medium circulation loop; the air super-cooler, the multi-stage compressor set and the air heat release side of the cold tank body are connected to the LNG vaporizer through the one-stage LNG cold storage medium circulation loop respectively.

[0024] The cold tank internal structure (which can be referred to as a "cold tank structure" or "structure" in the application) comprises at least one pair of heat exchangers and at least one set of cold tank cold storage working medium circulation loops. Each pair of heat exchangers is connected in series. Each pair of heat exchangers comprises an energy storage heat exchanger and an energy release heat exchanger, the air heat release side of each energy storage heat exchanger is connected to an energy storage pipeline, the air heat absorption side of each energy release heat exchanger is connected to an energy release pipeline, and the energy storage pipeline and the energy release pipeline are both connected to a liquid air storage tank. The structure can make air gradually liquefied to form liquid air in the energy storage stage, and make liquid air gradually heat up in the energy release stage. In the structure, the energy storage heat exchanger and the energy release heat exchanger of the same pair are both connected to the same cold tank circulation loop, and the cold tank circulation loop can introduce the heat energy of the energy storage heat exchanger into the energy release heat exchanger to provide heat energy for the air in the energy release stage, thereby realizing the cold storage in the energy storage stage and the heat release in the energy release stage of the liquid air energy storage. In the structure, at least one pair of heat exchangers is connected to the LNG cold energy utilization unit through a one-stage LNG cold storage medium circulation loop, and the one-stage LNG cold storage medium circulation loop can introduce the cold energy of the LNG cold energy utilization unit into the heat exchangers. In this process, the high-quality cold energy of the LNG can be fully transferred to the air liquefaction stage, the air liquefaction rate is improved, the air work capacity is enhanced, and the system work efficiency is improved.

[0025] Therefore, the cold box internal structure can effectively solve the defects of the existing liquid air energy storage system, such as insufficient stepwise recycling of LNG cold energy and excessive energy transmission loss caused by the high-grade cold energy unable to be directly transmitted to the air liquefaction process, thereby effectively realizing deep coupling of the high-grade cold energy generated in the LNG gasification process and the cold storage unit of the liquid air energy storage system, reducing the heat loss in the cold energy transmission process, improving the liquid air liquefaction rate, and achieving high efficiency.

[0026] The application also provides a liquid air energy storage power station, which comprises an LNG cold energy utilization unit, an air pretreatment unit, a cold box, an energy storage module, and an energy release module. The cold box comprises the cold box internal structure described above. The energy storage module comprises a multi-stage compressor set, an air heat release side of the cold box, a liquid expander, a throttle valve, a gas-liquid separator, and a liquid air storage tank connected in sequence. The energy release module comprises a multi-stage air expander set connected in sequence, and the liquid air storage tank is connected to the multi-stage air expander set through the air heat absorption side of the cold box internal structure. The air pretreatment unit is connected to the LNG cold energy utilization unit through a two-stage LNG cold storage medium circulation loop, the multi-stage compressor set and the air heat release side of the cold box are respectively connected to the LNG cold energy utilization unit through a one-stage LNG cold storage medium circulation loop, and the one-stage and two-stage LNG cold storage medium circulation loops can introduce the cold energy of the LNG cold energy utilization unit into the cold box, the multi-stage compressor set, and the air pretreatment unit, thereby realizing deep coupling of the high-grade cold energy of the LNG and the energy storage stage of the liquid air energy storage power station and direct utilization of the cold energy, reducing the heat loss in the cold energy transmission process, improving the liquid air liquefaction rate, and achieving high efficiency.

[0027] Moreover, the liquid air energy storage power station is provided with the cold box internal structure described above, so that the liquid air energy storage power station has all the advantages of the cold box internal structure described above, and details are not described here again. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0029] Figure 1 is one of the structure schematic diagrams of the liquid air energy storage power station provided by the application and adopting the cold box internal structure.

[0030] Figure 2 is the second structure schematic diagram of the liquid air energy storage power station provided by the application and adopting the cold box internal structure.

[0031] Figure 3 is one of the structural schematic diagrams of the internal structure of the cold box provided by the present application.

[0032] Figure 4 is one of the structural schematic diagrams of the internal structure of the cold box provided by the present application.

[0033] Figure 5 is one of the structural schematic diagrams of the internal structure of the cold box provided by the present application.

[0034] Figure 6 is one of the structural schematic diagrams of the internal structure of the cold box provided by the present application.

[0035] Reference signs:

[0036] 1, air filter; 2, molecular sieve purifier; 3, air precooler; 4, air supercooler; 5, primary air cryogenic compressor; 6, pre-cooler before secondary compressor stage; 7, secondary air cryogenic compressor; 8, pre-cooler before tertiary compressor stage; 9, tertiary air cryogenic compressor; 10, pre-cooler before quaternary compressor stage; 11, quaternary air cryogenic compressor; 12, liquid expander; 13, throttle valve; 14, gas-liquid separator; 15, liquid air storage tank; 16, liquid air pump; 17, cold box body; 18, pre-heater before primary expander stage; 19, primary air expander; 20, pre-heater before secondary expander stage; 21, secondary air expander; 22, pre-heater before tertiary expander stage; 23, tertiary air expander; 24, pre-heater before quaternary expander stage; 25, quaternary air expander; 26, natural gas superheater; 27, secondary LNG cold storage medium circulation loop; 28, LNG vaporizer; 29, primary LNG cold storage medium circulation loop; 101, energy storage pipeline; 102, energy release pipeline; 103, external discharge pipeline; 111, first heat exchanger; 112, second heat exchanger; 113, third heat exchanger; 114, fourth heat exchanger; 115, fifth heat exchanger; 116, evaporator; 117, working fluid turbine; 118, working fluid pump; 121, primary cold box cold storage working fluid circulation loop; 122, secondary cold box cold storage working fluid circulation loop; 123, organic working fluid Rankine cycle loop; 200, air pretreatment unit; 201, spray tower; 202, decarbonization unit; 203, secondary cold storage medium cold tank; 204, water solution concentration module; 205, secondary cold storage medium hot tank; 221, switchable heat exchanger; 222, primary cold storage medium cold tank; 223, primary cold storage medium hot tank; 224, heat pump air blowing and deicing module. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0038] The internal structure of the cold box and the liquid air energy storage power station adopting the internal structure of the cold box will be described below. Figures 1 to 5 The internal structure of the cold box and the liquid air energy storage power station adopting the internal structure of the cold box will be described below.

[0039] Figure 1 The specific equipment and pipeline connection structure of the internal structure of the cold box in the liquid air energy storage power station are shown in FIGS. 1-3. The liquid air energy storage power station comprises an LNG cold energy utilization unit and a liquid air energy storage system, and the LNG cold energy utilization unit and the liquid air energy storage system are deeply coupled to realize deep introduction of cold energy in the LNG vaporization process into the liquid air energy storage system for preparation and expansion power generation process of liquid air.

[0040] In the embodiments of the present application, as shown in FIGS. 1-3, Figure 1 and Figure 2 The liquid air energy storage system comprises an air pretreatment unit 200, a cold box body 17, an energy storage module and an energy release module. The cold box body 17 comprises the internal structure of the cold box described above, and the specific content of the internal structure of the cold box will be described in detail below, and will not be described here again. The energy storage module is installed on the energy storage pipeline. The energy storage module comprises a multi-stage compressor set, an air heat release side of the cold box body 17, a liquid expander 12, a throttle valve 13, a gas-liquid separator 14 and a liquid air storage tank 15 connected in sequence. The inlet end of the multi-stage compressor set is connected to the air pretreatment unit 200. The energy release module comprises a multi-stage air expander set connected in sequence, and the liquid air storage tank 15 is connected to the multi-stage air expander set through the air heat absorption side of the internal structure of the cold box. The energy storage module and the energy release module can respectively realize the treatment of air in the energy storage stage and the energy release stage of the liquid air energy storage power station, and the specific treatment process will be described in detail below, and will not be described here again.

[0041] In the embodiments of the present application, as shown in FIGS. 1-3, Figure 1 and Figure 2As shown, in order to efficiently couple the cold energy introduced from the LNG cold energy utilization unit into the liquid air energy storage system, the air pretreatment unit 200 is preferably connected to the LNG cold energy utilization unit through a two-stage LNG cold storage medium circulation loop 27. The air heat release side of the multi-stage compressor set and the cold box 17 are respectively connected to the LNG cold energy utilization unit through a one-stage LNG cold storage medium circulation loop 29. The two-stage LNG cold storage medium circulation loop 27 and the one-stage LNG cold storage medium circulation loop 29 can respectively introduce the cold energy of the LNG cold energy utilization unit into the air pretreatment unit 200 and the cold box 17, realize deep coupling of the high-grade cold energy of the LNG and the energy storage stage of the liquid air energy storage power station and direct utilization of the cold energy, reduce the heat loss in the cold energy transfer process, improve the liquefied air liquefaction rate, and realize high efficiency.

[0042] In some embodiments, as Figure 1 and Figure 2As shown, the energy storage module and the energy release module are connected. The energy storage module includes a multi-stage compressor set, an air heat release side of the cold box 17, a liquid expander 12, a throttling valve 13, a gas-liquid separator 14, and a liquid air storage tank 15. The energy storage module can use the multi-stage compressor set to compress the clean air after dehydration and decarburization in the energy storage stage, and the compressed air enters the cold box 17 for air cooling and liquefaction. The throttled liquid air is stored in the liquid air storage tank 15. The inlet end of the multi-stage compressor set is connected to the air pretreatment unit 200, so that the air entering the energy storage module is purified by the air pretreatment unit 200 to improve the cleanliness of the air. The air pretreatment unit 200 is connected to the natural gas superheater 26 of the LNG cold energy utilization unit through the two-stage LNG cold storage medium circulation loop 27, so that the cold energy of the LNG cold energy utilization unit is introduced into the air pretreatment unit 200. The multi-stage compressor set is connected to the LNG cold energy utilization unit through the one-stage LNG cold storage medium circulation loop 29, so that the medium- and low-quality cold energy in the LNG gasification process can be introduced and utilized in the pre-cooling process before the air compression stage, greatly reducing the compression power consumption and air purification cost, and improving the system electric-to-electric conversion efficiency and economic performance. Moreover, the energy storage module also uses the air heat release side of the cold box 17 to cool the compressed high-pressure air to a low temperature, and uses the one-stage LNG cold storage medium circulation loop 29 to introduce and utilize the cold energy in the LNG gasification process to the air cooling and liquefaction process, thereby improving the preparation efficiency of the liquid air. Preferably, the energy storage pipeline is provided with a liquid expander 12, and the liquid expander 12 is connected between the last-stage energy storage heat exchanger and the inlet end of the gas-liquid separator 14. Preferably, the energy storage pipeline is provided with a throttling valve 13, and the throttling valve 13 is connected between the last-stage liquid expander 12 and the inlet end of the gas-liquid separator 14. The low-temperature and high-pressure air is expanded and throttled by the liquid expander 12 and the throttling valve 13, and enters the gas-liquid separator 14 in the form of gas-liquid two-phase flow. The normal-pressure liquid air after separation is stored in the liquid air storage tank 15, thereby completing the energy storage process of the energy storage module. The gaseous air after separation is returned to the cold box as a backflow gas to supplement the cold quantity for the air liquefaction process, and then flows back to the inlet end of the air pretreatment unit 200 to participate in the new liquid air preparation process, for example Figure 1 As shown, the gaseous air after separation can also be directly discharged, for example Figure 2 As shown. The specific connection structure and working process of the gas-liquid separator 14 are described in detail below, and will not be described here.

[0043] In some embodiments, as shown in Figure 1 and Figure 2As shown, the energy releasing module includes a plurality of air expanders connected in series. The liquid air storage tank 15 is connected to the plurality of air expanders through the air heat absorption side of the cold box 17, so that the liquid air can be preheated by absorbing heat in the cold box 17 before entering the air turbine or expander. In the energy releasing stage, the air heat absorption side of the cold box 17 is preferably connected to the liquid air storage tank 15 through the liquid air pump 16, and the low-temperature and normal-pressure liquid air flowing out of the liquid air storage tank 15 is pressurized to high pressure by the liquid air pump 16, and then enters the air heat absorption side of the cold box 17 to absorb heat and vaporize and superheat to normal temperature. The low-temperature and normal-pressure liquid air absorbs the ambient heat or the surrounding low-grade heat source outside the liquid air energy storage power station to achieve superheating. The high-pressure gas after being heated enters the plurality of air expanders to realize step-by-step expansion of the air and output shaft power to the outside, thereby completing the energy releasing process of the liquid air energy storage device.

[0044] As can be understood, in the liquid air energy storage power station described in the embodiments of the present application, the energy releasing module is preferably connected to the power grid through the generator, so that the shaft power generated by the air expansion in the energy releasing stage drives the generator to generate electricity, thereby transmitting the electricity to the power grid, and realizing reliable application of the liquid air energy storage power station. The generation of electricity by the liquid air energy storage power station is only one application mode. As can be understood, the power station can also be applied to provide clean and dry compressed air to a park, provide cooling and heating, and other various applications.

[0045] As can be understood, in the liquid air energy storage power station described above, the plurality of air compressors preferably includes a plurality of air low-temperature compressors connected in series, and for each additional air low-temperature compressor 5, a corresponding air low-temperature compressor pre-cooler is connected in series before the air low-temperature compressor, so as to realize step-by-step compression and multi-stage pre-cooling of the air. For example Figure 1 As shown, the plurality of air compressors includes a first air low-temperature compressor 5, a second air low-temperature compressor 7 and a third air low-temperature compressor 9 connected in series through air pipelines, and a second compressor pre-cooler 6 is connected in series through an air pipeline between the first air low-temperature compressor 5 and the second air low-temperature compressor 7, and a third compressor pre-cooler 8 is connected in series through an air pipeline between the second air low-temperature compressor 7 and the third air low-temperature compressor 9. For another example Figure 2 As shown, the plurality of air compressors includes a first air low-temperature compressor 5, a second air low-temperature compressor 7, a third air low-temperature compressor 9 and a fourth air low-temperature compressor 11 connected in series through air pipelines, and a second compressor pre-cooler 6 is connected in series through an air pipeline between the first air low-temperature compressor 5 and the second air low-temperature compressor 7, a third compressor pre-cooler 8 is connected in series through an air pipeline between the second air low-temperature compressor 7 and the third air low-temperature compressor 9, and a fourth compressor pre-cooler 10 is connected in series through an air pipeline between the third air low-temperature compressor 9 and the fourth air low-temperature compressor 11.

[0046] Similarly, in the liquid air energy storage power station described above, the multi-stage air expander preferably comprises a plurality of air turbines or expanders connected in series, and a pre-heater is connected in series before each air turbine or expander to realize multi-stage temperature rise and step-by-step expansion of the air. Figure 1 As shown in the figure, the multi-stage air expander comprises a first-stage air expander 19, a second-stage air expander 21, a third-stage air expander 23 and a fourth-stage air expander 25 connected in series through an air pipeline, and a first-stage pre-heater 18 is connected in series before the first-stage air expander 19, a second-stage pre-heater 20 is connected in series through the air pipeline between the first-stage air expander 19 and the second-stage air expander 21, a third-stage pre-heater 22 is connected in series through the air pipeline between the second-stage air expander 21 and the third-stage air expander 23, and a fourth-stage pre-heater 24 is connected in series through the air pipeline between the third-stage air expander 23 and the fourth-stage air expander 25.

[0047] In some embodiments, preferably in the energy storage stage, the air at normal temperature and pressure is dehydrated and de-carbonated by the air pre-treatment unit 200 and pre-cooled to a low temperature. The purified air is compressed step by step to a high pressure by the multi-stage air compressor. The cold energy generated in the LNG gasification process is introduced between the air low-temperature compressors of the multi-stage air compressor to cool the air to a lower temperature. In the above process, the electricity for the air low-temperature compressors is supplied by renewable energy or off-peak power. Since the LNG gasification process is carried out all day long and the gasification amount is determined by the gas load of the downstream users, the cold storage medium circulation of each stage of the air purification system needs to be correspondingly arranged with cold tanks and hot tanks to recover the LNG cold energy in stages and output it stably. The specific connection structure of the cold storage medium circulation of each stage is described in detail below.

[0048] It should be noted that the normal pressure referred to in the present application is the conventional atmospheric pressure. In contrast, the high-pressure air is higher than the normal-pressure air, and the pressure of the high-pressure air depends on the working state of the compressor set. The lower limit of the pressure range of the high-pressure air is above the critical pressure of the air, and the upper limit of the pressure range of the high-pressure air depends on the manufacturing capacity and casting material of the compressor set. For example, the pressure range of the high-pressure air in the embodiments of the present application is selected to be below 20 MPa.

[0049] The following refers to Figures 3 to 5 The specific structure of the cold tank 17 is described in detail as follows.

[0050] The cold tank 17 provided by the embodiments of the present application comprises the following internal structure of the cold tank. As shown in the figure, Figures 3 to 5 The internal structure of the cold tank comprises at least one pair of heat exchangers and at least one set of cold tank circulation loops. Each pair of heat exchangers is connected step by step to liquefy the air introduced in the energy storage stage step by step and to raise the temperature of the air introduced in the energy release stage step by step.

[0051] In some embodiments, each pair of heat exchangers includes a charging heat exchanger and a discharging heat exchanger. The air heat-releasing side of each charging heat exchanger is connected to the charging pipeline 101, so that the air flowing through the charging heat exchanger is cooled. The air heat-absorbing side of each discharging heat exchanger is connected to the discharging pipeline 102, so that the air flowing through the discharging heat exchanger is heated. Both the charging pipeline 101 and the discharging pipeline 102 are connected to the liquid air storage tank 15, which can store the prepared liquid air. During the charging stage, the air flowing through the charging pipeline 101 is gradually cooled and liquefied by absorbing cold energy from each charging heat exchanger, and the formed liquid air is stored in the liquid air storage tank 15. During the discharging stage, the liquid air flowing out of the liquid air storage tank 15 is gradually heated by each discharging heat exchanger. The above structure can make the air flowing through the charging pipeline 101 gradually absorb cold energy from each charging heat exchanger during the charging stage, so that the air is cooled and liquefied to form liquid air which can be stored in the liquid air storage tank 15, and the liquid air flowing out of the liquid air storage tank 15 is gradually heated by each discharging heat exchanger during the discharging stage, so as to facilitate the air energy storage power plant to utilize air expansion to do work during the discharging stage.

[0052] In some embodiments, at least one pair of heat exchangers is connected to the LNG cold energy utilization unit through a first LNG cold storage medium circulation loop 29. The first LNG cold storage medium circulation loop 29 can introduce the cold energy of the LNG cold energy utilization unit into the charging heat exchanger, so as to provide cold energy for the high-pressure air flowing through the charging heat exchanger, and improve the air liquefaction rate and the electrical-to-electrical conversion efficiency of the liquid air energy storage system.

[0053] In some embodiments, the cold box working fluid heat-absorbing side of the charging heat exchanger and the cold box working fluid heat-releasing side of the discharging heat exchanger of the same pair are connected to the same cold box circulation loop. That is, the charging heat exchanger and the discharging heat exchanger of the same pair are connected in the same cold box circulation loop, and the cold box circulation loop introduces the heat energy of the charging heat exchanger into the discharging heat exchanger, so as to provide heat energy for the air flowing through the discharging pipeline 102, and form a cold-heat energy circulation inside the cold box 17.

[0054] In some embodiments, as shown in FIG. 1, the air energy storage power plant 1 includes a cold box circulation loop 30, which is connected to the charging pipeline 101 and the discharging pipeline 102. The cold box circulation loop 30 is connected to the cold box 17, and the cold box 17 is connected to the cold box circulation loop 30 through the charging pipeline 101 and the discharging pipeline 102. The cold box circulation loop 30 is connected to the charging pipeline 101 and the discharging pipeline 102 through the charging heat exchanger and the discharging heat exchanger of the same pair. Figures 3 to 5As shown, the energy storage pipeline 101 is connected to the liquid air storage tank 15 through the gas-liquid separator 14, which is provided with an external discharge pipeline 103 connected to the air heat absorption side of the energy storage heat exchanger, so that the residual cold energy in the process of preparing liquid air can be further recovered. Preferably, the reverse flow gas is discharged after flowing through the air heat release side of the cold box 17, so that the cold energy is released before the reverse flow gas is discharged, and the cold energy is stored in the cold box 17 to provide more cold energy for preparing liquid air in the energy storage stage, thereby improving the efficiency of the entire system. Preferably, the pipeline connecting the gas outlet of the gas-liquid separator 14 and the inlet end of the air pretreatment unit 200 can connect an air heat release side of the cold box 17, so that the cold energy carried by the reverse flow air in the process of preparing liquid air from compressed air can be recovered, which can improve the air liquefaction rate and improve the working efficiency of the liquid air energy storage power station. Preferably, the air flowing in the energy storage pipeline 101 is liquefied by absorbing cold energy step by step through each energy storage heat exchanger, and then enters the gas-liquid separator 14. The gas-liquid separator 14 separates the liquid air and passes it into the liquid air storage tank 15, and separates the reverse flow gas and passes it through the external discharge pipeline 103 to release cold energy from the energy storage heat exchanger, so that the residual cold energy in the reverse flow gas is stored in the energy storage heat exchanger and directly used for preparing liquid air, thereby improving the working efficiency of the liquid air energy storage system.

[0055] It should be noted that the reverse flow gas can be heated by an electric heater after leaving the cold box 17, and then reenters the molecular sieve purifier 2 of the air pretreatment unit 200 as clean regeneration gas to complete the regeneration process.

[0056] In some embodiments, the primary LNG cold storage medium circulation loop 29 and the secondary LNG cold storage medium circulation loop 27 both include a warming pipeline and a cooling pipeline. The warming pipeline can be connected to the energy storage heat exchanger or the energy release heat exchanger. The cooling pipeline is connected to the LNG cold energy utilization unit.

[0057] In the embodiments of the present application, as shown in Figure 3 At least one pair of heat exchangers includes a pair of primary heat exchangers. The pair of primary heat exchangers includes a first heat exchanger 111 and a second heat exchanger 112. The first heat exchanger 111 is an energy storage heat exchanger. The second heat exchanger 112 is an energy release heat exchanger. The first heat exchanger 111 is connected to the energy storage pipeline 101. The second heat exchanger 112 is connected to the energy release pipeline 102. The cold box working medium heat absorption side of the first heat exchanger 111 and the cold box working medium heat release side of the second heat exchanger 112 are connected through a primary cold box cold storage working medium circulation loop 121.

[0058] To improve the heat exchange efficiency, in some embodiments, at least one pair of heat exchangers further comprises a pair of secondary heat exchangers based on the above-mentioned primary heat exchangers. The pair of secondary heat exchangers comprises a third heat exchanger 113 and a fourth heat exchanger 114. The third heat exchanger 113 is an energy storage heat exchanger. The fourth heat exchanger 114 is an energy release heat exchanger. The energy storage pipeline 101 is connected in series between the first heat exchanger 111 and the third heat exchanger 113. The energy release pipeline 102 is correspondingly connected in series between the fourth heat exchanger 114 and the second heat exchanger 112. The cold box working medium heat absorption side of the third heat exchanger 113 and the cold box working medium heat release side of the fourth heat exchanger 114 are connected by a secondary cold box cold storage working medium circulation loop 122.

[0059] Referring to Figure 3 As shown in the cold box internal structure, in the energy storage phase, the air is compressed to high pressure by the multi-stage air compressor set, enters the inside of the cold box body 17, and is cooled to a lower temperature by the first heat exchanger 111 connected to the primary cold box cold storage working medium circulation loop 121. Then the low-temperature high-pressure air enters the third heat exchanger 113, and the primary LNG cold storage medium circulation loop 29 and the secondary cold box cold storage working medium circulation loop 122 are used to provide cold energy to the low-temperature high-pressure air at the same time, so that the air is liquefied to form liquid air. The liquid air enters the liquid expander 12 and the low-temperature throttling valve 13 in sequence and is expanded and throttled into gas-liquid two-phase mixture. The gas-liquid two-phase mixture air is separated in the gas-liquid separator 14, and the separated backflow gas is cooled by the third heat exchanger 113 and the first heat exchanger 111 in sequence and then discharged to the outside, and the liquid enters the liquid air storage tank 15 for storage. In the energy release phase, the liquid air drawn from the liquid air storage tank 15 is pressurized by the liquid air pump 16 to form high-pressure air; the high-pressure air is sequentially warmed and vaporized by the fourth heat exchanger 114 and the second heat exchanger 112, and finally leaves the cold box body 17 to enter the multi-stage expander set to absorb heat and expand to generate power.

[0060] Because Figure 3 Compared with the conventional liquid air energy storage system, the embodiment of the application shown in the energy storage phase, the third heat exchanger 113 increases the connection of the primary LNG cold storage medium circulation loop 29, so that the cold energy carried by the liquid air is not necessarily converted into temperature energy, and therefore the liquid air can be pressurized to a higher pressure in the energy release phase, and more of the cold energy of the liquid air itself can be converted into the pressure energy of the air itself, and the potential of the air entering the expansion unit to absorb heat and do work is increased.

[0061] Through the above system process, the expansion ratio of the liquid air in the energy releasing process is improved, the work capacity of the air in the expansion unit is increased, the power generation of the liquid air energy storage power station and the system efficiency are improved, and the liquid air energy storage system part of the original liquid air energy storage power station is less modified, the high-grade cold energy of LNG can be transferred to the liquid air in the form of cold energy, the energy devaluation of LNG cold energy in the transmission process is reduced, the utilization rate of LNG cold energy is higher, the coupling system efficiency is higher, the economy is better, and the liquid air energy storage system is promoted in the LNG cold energy utilization scene.

[0062] It should be noted that the first heat exchanger 111, the second heat exchanger 112, the third heat exchanger 113 and the fourth heat exchanger 114 can be one or a combination of a tube-shell structure, a plate-fin structure, a coiled tube structure, etc.

[0063] It should be noted that the temperature range of the high-pressure air entering the cold box 17 includes minus 100 degrees Celsius to 40 degrees Celsius.

[0064] It should be noted that the air pressure at the outlet end of the liquid air pump 16 is equal to or higher than 5 MPa.A.

[0065] In some embodiments, as shown in FIG. 1, the cold box 17 is connected to the energy storage pipeline 101 and the energy releasing pipeline 102, and the energy storage pipeline 101 and the energy releasing pipeline 102 are connected to the liquid air pump 16. Figure 4 As shown, for the cold box internal structure described in the above embodiments, the third heat exchanger 113 connected to the energy storage pipeline 101 in the energy storage stage has a total of four streams (heat exchange pipelines), while the fourth heat exchanger 114 connected to the energy releasing pipeline 102 in the energy releasing stage only needs two streams (heat exchange pipelines), which may make it more difficult to manufacture the third heat exchanger 113 compared to a conventional three-stream heat exchanger, resulting in a higher price. Therefore, the LNG-side primary cold storage medium can be applied to the fourth heat exchanger 114 in the cold box energy releasing stage for cold compensation, at this time the third heat exchanger 113 and the fourth heat exchanger 114 are both three streams, and the difficulty of equipment implementation is reduced, but since the cold energy in the primary LNG cold storage medium circulation loop 29 needs to be indirectly transferred to the air liquefaction process through the secondary cold box cold storage working medium circulation loop 122, there is a problem of energy devaluation, which is limited to the improvement of the energy storage system efficiency.

[0066] In some embodiments, for the coupled LNG cold energy utilization liquid air energy storage system using more compression stages and lower compressor inlet air temperature, the above system compression unit has higher demand for LNG high-quality cold energy, and lower air compression power consumption can be achieved. In the case of small final stage compressor pressure ratio and low inlet air temperature, the high-pressure air inlet cold box temperature is low, so the cold box internal structure described in the above embodiments does not need to be arranged with a multi-stage cold box circulation loop. Since there is only one stage of circulation in the cold box, the air cannot be heated to ambient temperature during the cold box rewarming process through multi-stage circulation, and there is still a large temperature difference between the air and the ambient temperature when the air exits the cold box second heat exchanger, so a power cycle needs to be added to recover this part of the cold energy. In view of this, the cold box internal structure described in the embodiments of the present application further includes an evaporator 116, a fifth heat exchanger 115, and an organic working medium Rankine cycle loop 123, as shown in Figure 5 The heat source heat release side of the evaporator 116 is connected to an external heat source. The organic working medium heat absorption side of the evaporator 116 and the organic working medium heat release side of the fifth heat exchanger 115 are connected through the organic working medium Rankine cycle loop 123. The energy release pipeline 102 is connected to the energy release heat exchanger and the fifth heat exchanger 115 in series. That is, the energy release pipeline 102 is connected to the second heat exchanger 112 and the fifth heat exchanger 115 in series, and the air is gradually warmed up in the energy release stage.

[0067] It should be noted that, considering that the power cycle uses a single working medium to recover the cold energy of the cold box air, there is a problem of poor temperature matching, so a mixed working medium is preferably used as the circulating working medium. Due to the temperature glide characteristics of the mixed working medium in the gas-liquid two-phase region, the heat exchange matching between the power cycle condensation process and the cold box air heating process can be enhanced, thereby improving the cold energy recovery rate of the cold box air. Preferably, the power cycle working medium in the organic working medium Rankine cycle loop 123 of the power cycle is one of methane, ethane, ethylene, propane, propylene, pentafluoropropane, trifluoromethane, difluoromethane, monofluoromethane, or a mixed working medium formed by mixing multiple working media in different proportions.

[0068] In some embodiments, when there is a medium-low temperature heat source available near the liquid air energy storage power station, the heat source can be used to heat the organic working medium in the power cycle. If the temperature difference between the heat source and the air introduced into the cold box body 17 is too large, an overlapped organic working medium Rankine cycle can be used to recover the residual cold energy of the cold box air and the medium-low grade heat energy of the heat source, that is, the top cycle condenser is used as the bottom cycle evaporator 116, and the bottom cycle is a composite system that condenses through the cold box air.

[0069] The specific structure of the air pretreatment unit is described in detail below.

[0070] In some embodiments, as shown in Figure 1 and Figure 2As shown, the air pre-treatment unit 200 includes an air filter 1, a molecular sieve purifier 2, an air pre-cooler 3, and an air sub-cooler 4. The air filter 1, the molecular sieve purifier 2, the air pre-cooler 3, the air sub-cooler 4, and the multi-stage compressor set are sequentially and serially connected to the energy storage pipeline 101. The air filter 1 is used for pre-filtering the air. The molecular sieve purifier 2 is used for removing organic impurities and carbon dioxide contained in the air, can filter and purify the air and remove carbon dioxide, and helps the backflow gas to complete the regeneration process.

[0071] As can be understood, the LNG cold energy utilization unit described in the embodiments of the present application includes an LNG vaporizer 28 and a natural gas superheater 26. The LNG vaporizer 28 and the natural gas superheater 26 are serially connected between an LNG input source and an NG output end in the LNG input direction, the LNG input source is connected to external LNG, and the NG output end is connected to external NG. LNG represents liquefied natural gas, and NG represents gaseous natural gas.

[0072] In some specific embodiments, the air pre-cooler 3 is connected to the natural gas superheater 26 through a two-stage LNG cold storage medium circulation loop 27, so as to lead out the cold energy of the natural gas superheater 26 to the air pre-treatment unit 200. The air sub-cooler 4, the multi-stage compressor set, and the air heat release side of the cold box 17 are respectively connected to the LNG vaporizer 28 through a one-stage LNG cold storage medium circulation loop 29, so as to lead in the cold energy of the LNG vaporizer 28 to the air pre-cooler 3, the multi-stage compressor set, and the cold box 17 in multiple stages. The above-mentioned arrangement can further improve the deep coupling between the LNG cold energy utilization unit and the liquid air energy storage system, lead out the cold energy to the liquid air energy storage system in a more direct manner, and improve the working efficiency of the system.

[0073] In some embodiments, as Figure 6 The structural schematic diagrams of various air pre-treatment units 200 are given.

[0074] As Figure 6As shown, the air pre-treatment unit 200 described in the embodiments of the present application comprises a spray tower 201 and a decarbonization unit 202. The spray tower 201 is connected to the air compressor unit through the decarbonization unit 202. The decarbonization unit 202 is at least used for further removing carbon dioxide from the dehydrated air. The spray tower 201 is connected to the secondary LNG cold storage medium circulation loop 27, that is, the secondary cold storage medium can be directly introduced into the spray tower 201 to directly contact with the air. The spray tower 201 is at least used for directly contacting the air with the secondary cold storage medium to dehydrate and cool the air flowing therethrough. The air pre-treatment unit 200 described in the present application can fully utilize the cold energy provided by the LNG cold energy utilization unit to realize the air spray dehydration in the spray tower 201. Compared with the scheme of realizing air dehydration and decarbonization by using the adsorption method and the freezing method in the prior art, the system has the advantages of simple structure, small pressure loss in the air dehydration and decarbonization purification process, low cost, and is more suitable for large-scale application, etc.

[0075] Specifically, the air pre-treatment unit 200 described in the present application can fully utilize the abundant cold energy resources in the LNG cold energy scenario, and use, for example, an alcohol-water solution as the secondary cold storage medium, so that it can directly contact and exchange heat with the air in the spray tower 201, thereby greatly improving the cooling effect of the air. Compared with the traditional air dehydration and decarbonization process, the process can greatly improve the air cooling effect, the air dehydration amount and the dehydration efficiency, and can also greatly reduce the pressure loss of the air purification process. This is more conducive to the application of the treated air in various power stations related to liquid air energy storage, such as liquid air energy storage power stations, which is more conducive to improving the electric power conversion efficiency. At the same time, the system can greatly reduce the use amount of adsorbents such as molecular sieves, greatly reduce the switching frequency of the switchable heat exchanger 221, and reduce the energy consumption of the air purification process. Once the investment is replaced by the potential economic loss brought by long-term operation investment. It has the advantages of high efficiency, environmental protection, safety, economy, etc.

[0076] It can be understood that the primary LNG cold storage medium circulation loop 29 is connected to the LNG vaporizer 28 and the multi-stage air compressor unit; and in some specific embodiments, the primary LNG cold storage medium circulation loop 29 is connected to the LNG vaporizer 28 and the decarbonization unit 202. Therefore, in order to ensure reliable transfer of cold energy, avoid cold energy loss and reliably improve heat exchange efficiency, the primary cold storage medium flowing in the primary LNG cold storage medium circulation loop 29 preferably uses propane as the main component of the cold storage medium.

[0077] It is understood that the secondary LNG cold storage medium circulation loop 27 is connected to the natural gas superheater 26 and the spray tower 201. In order to safely achieve direct contact heat exchange between air and the secondary cold storage medium, the secondary cold storage medium circulating in the secondary LNG cold storage medium circulation loop 27 is preferably an alcohol aqueous solution prepared by mixing at least one of methanol, ethylene glycol and propylene glycol with water in different proportions. A salt aqueous solution can also be selected as the secondary cold storage medium, but because the salt aqueous solution is corrosive, it can easily affect the service life of stainless steel equipment, so the salt aqueous solution is not the best choice.

[0078] In some embodiments, as shown in Figure 2 and Figure 6 The decarburization unit 202 includes at least two switchable heat exchangers 221 and at least one molecular sieve purifier 206. The specific selection of equipment for the decarburization unit 202 can be based on the material selection of the secondary cold storage medium introduced into the spray tower 201 in the air purification process. The specific selection is described as follows.

[0079] In some specific embodiments, corresponding to the selection of the secondary cold storage medium as an inorganic salt aqueous solution or a polyhydric alcohol aqueous solution as described above, as shown in Figure 6 The decarburization unit 202 preferably includes at least two switchable heat exchangers 221. The switchable heat exchangers 221 connected in parallel are used to further cool the air, and to remove carbon dioxide during the cooling process. Each group of switchable heat exchangers 221 is connected in parallel between the spray tower 201 and the air compressor unit. Each switchable heat exchanger 221 is connected to a primary LNG cold storage medium circulation loop 29, and each primary LNG cold storage medium circulation loop 29 is connected in parallel with each other, that is, the primary LNG cold storage medium circulation loop 29 includes a plurality of parallel first sub-loops, and the number of first sub-loops is the same as the number of switchable heat exchangers 221, so that each primary cold storage medium is introduced into the corresponding switchable heat exchanger 221, and the switchable heat exchanger 221 rapidly cools the air under the cold energy of the primary cold storage medium and freezes the carbon dioxide contained in the air in the heat exchanger, thereby achieving deep decarburization of the air.

[0080] In some specific embodiments, as shown in Figure 2As shown, the primary LNG cold storage medium circulation loop 29 includes a primary cold storage medium cold tank 222 and a primary cold storage medium hot tank 223. The functions of the cold and hot tanks have been explained above and will not be repeated here. A primary heat absorption pipeline and a primary heat release pipeline are connected between the primary cold storage medium cold tank 222 and the primary cold storage medium hot tank 223, respectively. The flow direction of the primary heat absorption pipeline is that the primary cold storage medium flows from the primary cold storage medium cold tank 222 to the primary cold storage medium hot tank 223 and is heated; the flow direction of the primary heat release pipeline is that the primary cold storage medium flows from the primary cold storage medium hot tank 223 to the primary cold storage medium cold tank 222 and is cooled. Each switching heat exchanger 221 is connected to the primary heat absorption pipeline to cool the air through heat exchange between the air and the primary cold storage medium, corresponding to the primary cold storage medium absorbing heat and heating up. The primary heat release pipeline is connected to the LNG vaporizer 28 of the LNG cold energy utilization unit to use the primary cold storage medium to remove the cold energy during the LNG vaporization process, thereby improving the LNG vaporization efficiency and utilizing the cold energy in the switching heat exchanger 221.

[0081] Similarly, the secondary LNG cold storage medium circulation loop 27 includes a secondary cold storage medium cold tank 203 and a secondary cold storage medium hot tank 205. The functions of the cold and hot tanks have been explained above and will not be repeated here. A secondary heat absorption pipeline and a secondary heat release pipeline are connected between the secondary cold storage medium cold tank 203 and the secondary cold storage medium hot tank 205, respectively. The flow direction of the secondary heat absorption pipeline is that the secondary cold storage medium flows from the primary cold storage medium cold tank 222 to the secondary cold storage medium hot tank 205 and is heated; the flow direction of the secondary heat release pipeline is that the secondary cold storage medium flows from the secondary cold storage medium hot tank 205 to the secondary cold storage medium cold tank 203 and is cooled. The spray tower 201 is connected to the secondary heat absorption pipeline to allow the secondary cold storage medium to be introduced into the spray tower 201, enabling direct contact and heat exchange between the air and the secondary cold storage medium. The moisture and heat in the air are carried back to the secondary cold storage medium hot tank 205 by the secondary cold storage medium. The secondary heat release pipeline is connected to the natural gas superheater 26 of the LNG cold energy utilization unit to use the secondary cold storage medium to remove the cold energy in the LNG gasification process, improve the LNG gasification efficiency, and utilize the cold energy in the spray tower 201.

[0082] In some specific embodiments, such as Figure 2 As shown, the decarbonization unit 202 also includes a heat pump blowing de-icing module. The heat pump blowing de-icing module is connected to each switching heat exchanger 221. The heat pump blowing de-icing module is used to blow air into the switching heat exchanger 221 for de-icing, to prevent the temperature of the switching heat exchanger 221 from being too low and affecting the subsequent continuous decarbonization, thereby improving the system's working efficiency and quality.

[0083] In some specific embodiments, such as Figure 2As shown, the air pre-treatment unit 200 further comprises a water solution concentration module 204. The water solution concentration module 204 is installed on the secondary heat absorption pipeline and connected between the spray tower 201 and the secondary cold storage medium heat tank 205. During the circulation of the secondary cold storage medium in the secondary LNG cold storage medium circulation loop 27, the solution composition of the secondary cold storage medium will change greatly after the system runs for multiple energy storage stages. The water solution concentration module 204 can concentrate the solution to the initial concentration, preventing the increase of the water component from affecting the solution physical properties of the secondary cold storage medium, affecting the cold energy recovery efficiency and the overall working efficiency and quality of the system.

[0084] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cold box internal structure, characterized by, The system comprises at least one pair of heat exchangers and at least one set of cold box circulation loops, Each pair of heat exchangers is connected in stages, and at least one pair of heat exchangers is connected to an LNG cold energy utilization unit through a primary LNG cold storage medium circulation loop (29); each pair of heat exchangers comprises a storage heat exchanger and a release heat exchanger, the air heat releasing side of each stage of the storage heat exchanger is connected to a storage pipeline (101), the air heat absorbing side of each stage of the release heat exchanger is connected to a release pipeline (102), and the storage pipeline (101) and the release pipeline (102) are both connected to a liquid air storage tank (15); the cold box working medium heat absorbing side of the storage heat exchanger and the cold box working medium heat releasing side of the release heat exchanger of the same pair are both connected to the same cold box circulation loop; In the storage stage, the air flowing in the storage pipeline (101) absorbs cold energy and is liquefied in stages through each storage heat exchanger, and the formed liquid air is stored in the liquid air storage tank (15); In the release stage, the liquid air flowing out of the liquid air storage tank (15) is pressurized and then absorbs heat and is heated in stages through each release heat exchanger; The primary LNG cold storage medium circulation loop (29) introduces the cold energy of the LNG cold energy utilization unit into the storage heat exchanger to provide cold energy for high-pressure air flowing through the storage heat exchanger; The cold box circulation loop introduces the heat energy of the storage heat exchanger into the release heat exchanger to provide heat energy for high-pressure air flowing through the release pipeline (102); At least one pair of heat exchangers comprises a pair of primary heat exchangers, and a pair of primary heat exchangers comprises a first heat exchanger (111) and a second heat exchanger (112), the first heat exchanger (111) is the storage heat exchanger, the second heat exchanger (112) is the release heat exchanger, the first heat exchanger (111) is connected to the storage pipeline (101), and the second heat exchanger (112) is connected to the release pipeline (102); The cold box working medium heat absorbing side of the first heat exchanger (111) and the cold box working medium heat releasing side of the second heat exchanger (112) are connected through a primary cold box cold storage working medium circulation loop (121); At least one pair of heat exchangers further comprises a pair of secondary heat exchangers, and a pair of secondary heat exchangers comprises a third heat exchanger (113) and a fourth heat exchanger (114), the third heat exchanger (113) is the storage heat exchanger, and the fourth heat exchanger (114) is the release heat exchanger; The storage pipeline (101) is connected to the first heat exchanger (111) and the third heat exchanger (113) in stages, and the release pipeline (102) is correspondingly connected to the fourth heat exchanger (114) and the second heat exchanger (112) in stages; The cold box working medium heat absorbing side of the third heat exchanger (113) and the cold box working medium heat releasing side of the fourth heat exchanger (114) are connected through a secondary cold box cold storage working medium circulation loop (122).

2. The cold box internal structure of claim 1, wherein, The energy storage pipeline (101) is connected with the liquid air storage tank (15) through a gas-liquid separator (14), and the gas-liquid separator (14) is provided with an exhaust pipeline (103) connected with the air heat absorption side of the energy storage heat exchanger. The high-pressure air flowing in the energy storage pipeline (101) absorbs cold energy and is liquefied by step-by-step passing through each energy storage heat exchanger, and after being expanded and throttled to normal pressure, the air is introduced into the gas-liquid separator (14), the gas-liquid separator (14) separates out the liquid air and introduces the liquid air into the liquid air storage tank (15), and the backflow gas separated out is introduced into the energy storage heat exchanger through the exhaust pipeline (103) to release cold energy.

3. The cold box internal structure of claim 2, wherein, The energy storage pipeline (101) is provided with a liquid expander (12) connected between the last-stage energy storage heat exchanger and the inlet end of the gas-liquid separator (14).

4. The cold box internal structure of claim 3, wherein, The energy storage pipeline (101) is provided with a throttle valve (13) connected between the last-stage liquid expander (12) and the inlet end of the gas-liquid separator (14).

5. Cold box interior structure according to any of claims 1 - 4, characterized in that The primary LNG cold storage medium circulation loop (29) comprises a temperature rising pipeline connected with the energy storage heat exchanger or the energy release heat exchanger, and a temperature dropping pipeline connected with the LNG cold energy utilization unit.

6. Cold box interior structure according to any of claims 1 - 4, characterized in that Further comprising an evaporator (116), a fifth heat exchanger (115) and an organic working medium Rankine cycle loop (123), the heat source heat releasing side of the evaporator (116) is connected with an external heat source, and the organic working medium heat absorbing side of the evaporator (116) and the organic working medium heat releasing side of the fifth heat exchanger (115) are connected through the organic working medium Rankine cycle loop (123). The energy release pipeline (102) is connected with the energy release heat exchanger and the fifth heat exchanger (115) in series.

7. A liquid air energy storage power plant characterized in that, Comprise: The LNG cold energy utilization unit; The air pretreatment unit (200); The cold box body (17) comprises the cold box internal structure according to any one of claims 1-6; The energy storage module comprises a multi-stage compressor set, an air heat releasing side of the cold box body (17), a liquid expander (12), a throttle valve (13), a gas-liquid separator (14) and a liquid air storage tank (15) connected in series, the inlet end of the multi-stage compressor set is connected with the air pretreatment unit (200), the air pretreatment unit (200) is connected with the LNG cold energy utilization unit through a secondary LNG cold storage medium circulation loop (27), and the multi-stage compressor set and the air heat releasing side of the cold box body (17) are respectively connected with the LNG cold energy utilization unit through a primary LNG cold storage medium circulation loop (29); The energy release module comprises a multi-stage air expander set, and the liquid air storage tank (15) is connected with the multi-stage air expander set through the air heat absorbing side of the cold box internal structure.

8. A liquid air energy storage power plant according to claim 7, characterised in that, The air pre-treatment unit (200) comprises an air filter (1), a molecular sieve purifier (2), an air pre-cooler (3) and an air super-cooler (4), the air filter (1), the molecular sieve purifier (2), the air pre-cooler (3), the air super-cooler (4) and the multi-stage compressor group are connected in sequence in series to the energy storage pipeline (101); The LNG cold energy utilization unit comprises a LNG vaporizer (28) and a natural gas superheater (26) connected in series; The air pre-cooler (3) is connected to the natural gas superheater (26) through the secondary LNG cold storage medium circulation loop (27); The air super-cooler (4), the multi-stage compressor group and the air heat release side of the cold box body (17) are respectively connected to the LNG vaporizer (28) through the primary LNG cold storage medium circulation loop (29).

Images