A liquid air energy storage system with coupled air separation device

Abstract

This invention provides a liquid air energy storage system coupled with an air separation device, relating to the field of energy storage technology. The liquid air energy storage system with coupled air separation device includes an air compressor, a cold storage device, a liquid air tank, a distillation unit, a heating unit, and an expander unit. The air compressor is used to compress air; the cold storage device is connected to the air compressor. By connecting the cold storage device to the distillation unit, nitrogen and waste nitrogen produced by the distillation unit can be used to supplement the cooling of the cold storage device, thereby reducing the size of the cold storage device; liquid air produced during off-peak electricity pricing periods can be used directly to supplement the cooling of the distillation unit, reducing the operating cost of the distillation unit; and exhaust gas from the expander unit can be used to provide clean air to the distillation unit, reducing energy loss. The liquid air energy storage system provided by this invention has superior economic performance and a high comprehensive utilization rate of liquid air, broadening the application scenarios for liquid air energy storage systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, and in particular to a liquid air energy storage system coupled with an air separation device. BACKGROUND

[0002] With the depletion of fossil energy, the global energy structure is undergoing an unprecedented transformation. Renewable energy such as solar and wind energy is considered as a substitute for fossil energy due to its clean and sustainable characteristics. According to the data statistics of International Energy Agency in 2023, the proportion of renewable energy power generation in China reaches 31.2%. However, the volatility and intermittency of renewable energy pose great challenges to the operation of power grid stability. The development of energy storage technology provides an effective way to solve this problem.

[0003] Liquid air energy storage technology stands out among many energy storage technologies due to its high energy storage density, no geographical condition limitation, and constant pressure storage. Liquid air energy storage technology stores energy during off-peak hours and releases energy during peak hours to balance power supply and demand and improve the peak shaving capacity of power grid. For liquid air energy storage technology, due to the existence of cryogenic process, there is a certain cleanliness requirement for the air entering the cold storage unit, so the air needs to be purified in advance to remove water, carbon dioxide and other impurities. During the energy release process of the energy storage system, the purified air is only used for expansion power generation and then released to the external environment, so the liquid air energy storage technology lacks the use of purified air.

[0004] Air separation technology refers to the use of related equipment and technology to separate nitrogen, oxygen and other rare gases from air to meet the demand for various gases in industries such as metallurgy, coal chemical industry, petroleum refining, aviation, etc. Air separation technology generally uses cryogenic process to separate air, which has certain requirements for air cleanliness and consumes a large amount of electric energy.

[0005] During the operation of the liquid air energy storage system, a molecular sieve purifier is usually used to purify the air to remove water, carbon dioxide and hydrocarbons in the air, and the energy consumption of the purification process is high. The purified air after expansion is directly discharged into the atmosphere in the liquid air energy storage system, which causes energy loss. In addition, the air separation device needs to be operated stably, and the electricity consumption in each time period is relatively fixed. Since industrial electricity adopts time-of-use electricity price policy, the operation cost of the air separation device in the peak electricity price period is high. SUMMARY

[0006] The present application provides a liquid air energy storage system coupled with an air separation device to solve the problems of high energy consumption and high operation cost of the existing liquid air energy storage system.

[0007] The present application provides a liquid air energy storage system coupled with an air separation device, comprising:

[0008] an air compression device for compressing air;

[0009] a cold storage device in communication with the air compression device, for cooling high-pressure air delivered by the air compression device to convert part of the high-pressure air into liquid air;

[0010] a liquid air tank in communication with the cold storage device;

[0011] a rectification device in communication with the cold storage device, the rectification device being in communication with the liquid air tank through a first liquid air pump, the liquid air tank being used for storing liquid air and delivering liquid air to the rectification device through the first liquid air pump for cold compensation;

[0012] a heating device in communication with the liquid air tank and the rectification device, the heating device being used for heating liquid air output by the liquid air tank to obtain high-pressure normal-temperature air;

[0013] an expander device in communication with the heating device and the air compression device, the expander device being used for generating power by high-pressure normal-temperature air during peak electricity price period.

[0014] According to the liquid air energy storage system coupled with an air separation device provided by the application, the air compression device comprises:

[0015] a plurality of compressors;

[0016] a plurality of inter-stage coolers, adjacent two of the compressors being in communication through corresponding inter-stage coolers, an air outlet of the inter-stage cooler of the highest stage being in communication with the cold storage device, and a liquid outlet and a liquid inlet of each of the inter-stage coolers being in communication with the expander device.

[0017] According to the liquid air energy storage system coupled with an air separation device provided by the application, the air compression device further comprises:

[0018] a first connecting pipeline, an air outlet of one of the inter-stage coolers of the plurality of inter-stage coolers being in communication with the cold storage device through the first connecting pipeline.

[0019] According to the liquid air energy storage system coupled with an air separation device provided by the application, the cold storage device comprises:

[0020] a first cold storage unit;

[0021] A second stage cold storage unit, the first stage cold storage unit and the second stage cold storage unit are connected in series in a liquid phase air input pipeline, a gas phase air output pipeline, a liquid oxygen output pipeline, a nitrogen output pipeline and a waste nitrogen output pipeline, wherein an input end of the liquid phase air input pipeline is communicated with the first connecting pipeline and a gas outlet of the highest stage inter-stage cooler, an output end of the liquid phase air input pipeline is communicated with the liquid air tank through a first liquid expander and a throttle valve in sequence; an input end of the gas phase air output pipeline is communicated with the liquid air tank; input ends of the liquid oxygen output pipeline, the nitrogen output pipeline and the waste nitrogen output pipeline are communicated with the rectification device.

[0022] According to the application, a liquid air energy storage system coupled with an air separation device is provided, the cold storage device further comprises:

[0023] An air expander, the liquid phase air input pipeline between the first stage cold storage unit and the second stage cold storage unit is communicated with an input end of the air expander, and an output end of the air expander is communicated with the rectification device;

[0024] A second liquid expander, the liquid phase air input pipeline between the second stage cold storage unit and the first liquid expander is communicated with an input end of the second liquid expander, and an output end of the second liquid expander is communicated with the rectification device.

[0025] According to the application, a liquid air energy storage system coupled with an air separation device is provided, the heating device comprises:

[0026] A first air heater;

[0027] A second air heater, the first air heater and the second air heater are connected in series in a liquid phase air output pipeline, an input end of the liquid phase air output pipeline is communicated with the liquid air tank through a second liquid air pump, and an output end of the liquid phase air output pipeline is communicated with the expander device; the first air heater is communicated with the first stage cold storage unit through a circulating pipeline, and the second air heater is communicated with the second stage cold storage unit through a circulating pipeline.

[0028] According to the application, a liquid air energy storage system coupled with an air separation device is provided, the expander device comprises:

[0029] A multi-stage inter-stage heater;

[0030] A multi-stage expander, adjacent two stages of the expander are communicated through a corresponding inter-stage heater, and an air inlet of a lowest stage inter-stage heater is communicated with an output end of the liquid phase air output pipeline.

[0031] A high temperature water tank, a liquid inlet of the high temperature water tank being communicated with a liquid outlet of each inter-stage cooler, a liquid outlet of the high temperature water tank being communicated with a liquid inlet of each inter-stage heater;

[0032] A low temperature water tank, a liquid inlet of the low temperature water tank being communicated with a liquid outlet of each inter-stage cooler, a liquid outlet of the low temperature water tank being communicated with a liquid inlet of each inter-stage heater.

[0033] According to the present application, a liquid air energy storage system coupled with an air separation unit is provided, the expander device further comprising:

[0034] A third liquid air pump, the third liquid air pump being arranged at the liquid outlet of the high temperature water tank;

[0035] A fourth liquid air pump, the fourth liquid air pump being arranged at the liquid outlet of the low temperature water tank;

[0036] A first cooler, the first cooler being arranged at the liquid inlet of the low temperature water tank.

[0037] According to the present application, a liquid air energy storage system coupled with an air separation unit is provided, the expander device further comprising:

[0038] A gas return pipeline, a gas inlet end of the gas return pipeline being communicated with a gas inlet of one of the inter-stage heaters, a gas outlet end of the gas return pipeline being communicated with the rectification device;

[0039] A second cooler, the second cooler being connected in series with the gas return pipeline.

[0040] According to the present application, a liquid air energy storage system coupled with an air separation unit is provided, the expander device further comprising:

[0041] A second connecting pipeline, a liquid inlet end of the second connecting pipeline being communicated with a liquid outlet of the third liquid air pump, a liquid outlet end of the second connecting pipeline being communicated with a liquid inlet end of the second cooler;

[0042] A Rankine cycle power generation device, an inter-stage heater of the Rankine cycle power generation device being connected in series with the second connecting pipeline.

[0043] The liquid air energy storage system coupled with the air separation device provided by the application can utilize nitrogen and waste nitrogen produced by the rectification device to supplement the cold storage device, so as to reduce the size of the cold storage device; the liquid air produced in the trough electricity price period is directly used to supplement the rectification device, so as to reduce the operation cost of the rectification device; the exhaust of the expander device is used to provide pure air for the rectification device, so as to reduce energy loss. The liquid air energy storage system provided by the application has better economic performance, higher comprehensive utilization rate of liquid air, and wider application scenarios of the liquid air energy storage system. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or 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.

[0045] Figure 1 FIG. 1 is a structural schematic diagram of the liquid air energy storage system coupled with the air separation device provided by the application.

[0046] Reference signs:

[0047] 1, first-stage compressor; 2, second-stage compressor; 3, third-stage compressor; 4, fourth-stage compressor; 5, first-stage inter-stage cooler; 6, second-stage inter-stage cooler; 7, third-stage inter-stage cooler; 8, fourth-stage inter-stage cooler; 9, low-temperature water tank; 10, high-temperature water tank; 11, first-stage cold storage unit; 12, second-stage cold storage unit; 13, air expander; 14, throttle valve; 15, liquid air tank; 16, first liquid air pump; 17, first liquid expander; 18, second liquid air pump; 19, first air heater; 20, second air heater; 21, first-stage inter-stage heater; 22, second-stage inter-stage heater; 23, third-stage inter-stage heater; 24, fourth-stage inter-stage heater; 25, first-stage expander; 26, second-stage expander; 27, third-stage expander; 28, fourth-stage expander; 29, second cooler; 30, rectification device; 31, first liquid expander; 32, third liquid air pump; 33, fourth liquid air pump; 34, first cooler; 36, high-temperature medium storage tank; 37, high-temperature pump; 38, low-temperature medium storage tank; 39, low-temperature pump; 40, first connecting pipeline; 41, liquid-phase air input pipeline; 42, gas-phase air output pipeline; 43, liquid oxygen output pipeline; 44, nitrogen output pipeline; 45, waste nitrogen output pipeline; 46, return air pipeline; 47, Rankine cycle power generation device; 48, liquid-phase air output pipeline; 49, second connecting pipeline. DETAILED DESCRIPTION

[0048] So that the objectives, technical solutions and advantages of the present application are more apparent, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not 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 fall within the scope of the present application.

[0049] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0050] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0051] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or it can only mean that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or it can only mean that the horizontal height of the first feature is less than that of the second feature.

[0052] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0053] The specific structure and working principle of the liquid air energy storage system coupled with the air separation device of the present application are described below. Figure 1 The specific structure and working principle of the liquid air energy storage system coupled with the air separation device of the present application are described below.

[0054] As shown in Figure 1 The liquid air energy storage system coupled with the air separation device includes an air compression device, a cold storage device, a liquid air tank 15, a rectification device 30, a heating device and an expander device. The air compression device is used for compressing air. The cold storage device is in communication with the air compression device. The cold storage device is used for cooling the high-pressure air delivered by the air compression device, so that part of the high-pressure air is converted into liquid air. The liquid air tank 15 is in communication with the cold storage device. The rectification device 30 is in communication with the liquid air tank 15 through a first liquid air pump 16. The cold storage device is in communication with the rectification device 30. The liquid air tank 15 is used for storing liquid air and delivering the liquid air to the rectification device 30 through the first liquid air pump 16 for cold compensation. The heating device is in communication with the liquid air tank 15 and the rectification device 30. The heating device is used for heating the liquid air output by the liquid air tank 15 to obtain high-pressure normal-temperature air. The expander device is in communication with the heating device and the air compression device. The expander device is used for generating power by the high-pressure normal-temperature air during the peak electricity price period.

[0055] The liquid air energy storage system coupled with the air separation device provided by the present application can utilize the nitrogen and waste nitrogen produced by the rectification device 30 to compensate the cold storage device, so as to reduce the size of the cold storage device. The liquid air produced during the valley electricity price period is directly used to compensate the rectification device 30, so as to reduce the operation cost of the rectification device 30. The exhaust gas of the expander device is used to provide pure air for the rectification device 30, so as to reduce the energy loss. The liquid air energy storage system provided by the present application has better economic performance and higher comprehensive utilization rate of liquid air, which widens the application scenarios of the liquid air energy storage system.

[0056] In one embodiment of the present application, the air compression device comprises multi-stage compressors and multi-stage inter-stage coolers, two adjacent compressors are connected through corresponding inter-stage coolers, the outlet of the highest stage inter-stage cooler is connected with the cold storage device, and the outlet and inlet of each inter-stage cooler are connected with the expander device.

[0057] Specifically, the air compression device comprises a first stage compressor 1, a second stage compressor 2, a third stage compressor 3, a fourth stage compressor 4, a first stage inter-stage cooler 5, a second stage inter-stage cooler 6, a third stage inter-stage cooler 7 and a fourth stage inter-stage cooler 8, of course, the number of compressors and the number of inter-stage coolers are not limited to this, and are determined according to actual needs.

[0058] The first stage inter-stage cooler 5 is located between the first stage compressor 1 and the second stage compressor 2, the outlet of the first stage compressor 1 is connected with the inlet of the first stage inter-stage cooler 5, and the outlet of the first stage inter-stage cooler 5 is connected with the inlet of the second stage compressor 2. The second stage inter-stage cooler 6 is located between the second stage compressor 2 and the third stage compressor 3, the outlet of the second stage compressor 2 is connected with the inlet of the second stage inter-stage cooler 6, and the outlet of the second stage inter-stage cooler 6 is connected with the inlet of the third stage compressor 3. The third stage inter-stage cooler 7 is located between the third stage compressor 3 and the fourth stage compressor 4, the outlet of the third stage compressor 3 is connected with the inlet of the third stage inter-stage cooler 7, and the outlet of the third stage inter-stage cooler 7 is connected with the inlet of the fourth stage compressor 4. The inlet of the fourth stage inter-stage cooler 8 is connected with the outlet of the fourth stage compressor 4, and the outlet of the fourth stage inter-stage cooler 8 is connected with the inlet of the first stage cold storage unit 11.

[0059] It should be noted that the use of "stage" to limit the compressor and the inter-stage cooler in the present application is only for the purpose of distinguishing each compressor and each inter-stage cooler for easy description, and has no substantive meaning.

[0060] In a preferred embodiment of the present application, a molecular sieve purifier is connected in series between the outlet of the first stage inter-stage cooler 5 and the inlet of the second stage compressor 2, which is used to remove water, carbon dioxide, hydrocarbons and other substances in the air to prevent the pipeline from being blocked.

[0061] In one embodiment of the present invention, the air compression device further includes a first connecting pipe 40, through which the outlet of one of the interstage coolers in the multi-stage intercooler is connected to the cold storage device. Specifically, one end of the first connecting pipe 40 is connected to the outlet of the second-stage interstage cooler 6, and the other end of the first connecting pipe 40 is connected to the inlet of the first-stage cold storage unit 11. The first connecting pipe 40 is provided to allow a portion of the air to enter the first-stage cold storage unit 11 to obtain cooling. After being cooled by the first-stage cold storage unit 11, this portion of air enters the air expander 13 for expansion and finally enters the distillation unit 30.

[0062] In one embodiment of the present invention, the cold storage device includes a first-stage cold storage unit 11 and a second-stage cold storage unit 12. The first-stage cold storage unit 11 and the second-stage cold storage unit 12 have the same function, both used to cool high-pressure air and ultimately liquefy it. The first-stage cold storage unit 11 and the second-stage cold storage unit 12 are connected in series to a liquid air input pipeline 41, a gaseous air output pipeline 42, a liquid oxygen output pipeline 43, a nitrogen output pipeline 44, and a waste nitrogen output pipeline 45. The input end of the liquid air input pipeline 41 is connected to the first connecting pipeline 40 and the outlet of the highest-level interstage cooler. The output end of the liquid air input pipeline 41 is connected to a liquid air tank 15 in sequence through a first liquid expander 31 and a throttle valve 14. The input end of the gaseous air output pipeline 42 is connected to the liquid air tank 15. The input ends of the liquid oxygen output pipeline 43, the nitrogen output pipeline 44, and the waste nitrogen output pipeline 45 are all connected to a distillation unit 30.

[0063] Specifically, such as Figure 1 As shown, the first-stage cold storage unit 11 and the second-stage cold storage unit 12 each have multiple inlets and multiple outlets. One inlet on the right side of the second-stage cold storage unit 12 is connected to the liquid air tank 15 via a gas phase air output pipeline 42. Another inlet on the right side of the second-stage cold storage unit 12 is connected to the liquid oxygen outlet of the distillation unit 30 via a liquid oxygen output pipeline 43. A third inlet on the right side of the second-stage cold storage unit 12 is connected to the nitrogen outlet of the distillation unit 30 via a nitrogen output pipeline 44. A fourth inlet on the right side of the second-stage cold storage unit 12 is connected to the waste nitrogen outlet of the distillation unit 30 via a waste nitrogen output pipeline 45. One outlet on the right side of the second-stage cold storage unit 12 is connected to the input end of the first liquid expander 31 via a liquid phase air input pipeline 41. The output port of the first liquid expander 31 is connected to the liquid air tank 15 via a throttle valve 14.

[0064] One of the inlets on the right side of the first stage cold storage unit 11 is communicated with one of the outlets on the left side of the second stage cold storage unit 12 through a section of gaseous air output pipeline 42, one of the inlets on the right side of the first stage cold storage unit 11 is communicated with one of the outlets on the left side of the second stage cold storage unit 12 through a section of liquid oxygen output pipeline 43, one of the inlets on the right side of the first stage cold storage unit 11 is communicated with one of the outlets on the left side of the second stage cold storage unit 12 through a section of nitrogen output pipeline 44, and one of the inlets on the right side of the first stage cold storage unit 11 is communicated with one of the outlets on the left side of the second stage cold storage unit 12 through a section of waste nitrogen output pipeline 45. One of the outlets on the right side of the first stage cold storage unit 11 is communicated with one of the inlets on the left side of the second stage cold storage unit 12 through a section of liquid phase air input pipeline 41. The four outlets on the left side of the first stage cold storage unit 11 are communicated with the gaseous air output pipeline 42, the liquid oxygen output pipeline 43, the nitrogen output pipeline 44 and the waste nitrogen output pipeline 45 respectively, and one of the inlets on the left side of the first stage cold storage unit 11 is communicated with the other end of the first connecting pipeline 40 and the gas outlet of the fourth stage inter-cooler 8 through a section of liquid phase air input pipeline 41.

[0065] In one embodiment of the present application, the cold storage device further comprises an air expander 13 and a second liquid expander 17, the liquid phase air input pipeline 41 between the first stage cold storage unit 11 and the second stage cold storage unit 12 is communicated with the input end of the air expander 13, and the output end of the air expander 13 is communicated with the rectification device 30. The liquid phase air input pipeline 41 between the second stage cold storage unit 12 and the first liquid expander 31 is communicated with the input end of the second liquid expander 17, and the output end of the second liquid expander 17 is communicated with the rectification device 30. The air expander 13 is used for expanding part of the air output by the first stage cold storage unit 11, and the expanded air enters the rectification device 30, and the second liquid expander 17 is used for expanding part of the air output by the second stage cold storage unit 12, and the expanded air enters the rectification device 30.

[0066] In one embodiment of the present application, the heating device comprises a first air heater 19 and a second air heater 20, the first air heater 19 and the second air heater 20 are connected in series in the liquid phase air output pipeline 48, the input end of the liquid phase air output pipeline 48 is communicated with the liquid air tank 15 through the second liquid air pump 18, and the output end of the liquid phase air output pipeline 48 is communicated with the expander device; the first air heater 19 is communicated with the first stage cold storage unit 11 through a circulating pipeline, and the second air heater 20 is communicated with the second stage cold storage unit 12 through a circulating pipeline. The first air heater 19 and the second air heater 20 are respectively used for heating the liquid air in the liquid phase air output pipeline 48, so that the liquid air is gasified.

[0067] In one specific embodiment of the present application, the circulation pipeline comprises a high-temperature medium storage tank 36, a high-temperature pump 37, a low-temperature medium storage tank 38 and a low-temperature pump 39, the output end of the high-temperature medium storage tank 36 is communicated with the input end of the high-temperature pump 37, the output end of the high-temperature pump 37 is communicated with the inlet of the air heater (the first air heater 19 or the second air heater 20), the outlet of the air heater (the first air heater 19 or the second air heater 20) is communicated with the input end of the low-temperature medium storage tank 38, the output end of the low-temperature medium storage tank 38 is communicated with the input end of the low-temperature pump 39, the output end of the low-temperature pump 39 is communicated with the inlet of the cold storage unit (the first-stage cold storage unit 11 or the second-stage cold storage unit 12), and the outlet of the cold storage unit (the first-stage cold storage unit 11 or the second-stage cold storage unit 12) is communicated with the input end of the high-temperature medium storage tank 36. The high-temperature medium in the high-temperature medium storage tank 36 is pumped to the first air heater 19 or the second air heater 20 by the high-temperature pump 37 to heat the liquid-phase air in the liquid-phase air output pipeline 48, and the temperature of the medium is reduced after heat exchange and enters the low-temperature medium storage tank 38, which is pumped to the first-stage cold storage unit 11 or the second-stage cold storage unit 12 by the low-temperature pump 39 to cool the air in the liquid-phase air input pipeline 41, and the temperature of the medium is increased after heat exchange and returns to the high-temperature medium storage tank 36.

[0068] Further, the circulation pipeline further comprises a first circulation pump, a second circulation pump and a fifth inter-stage heater, the output end of the first circulation pump is communicated with the output end of the high-temperature pump 37, the input end of the second circulation pump is communicated with the input end of the low-temperature medium storage tank 38, the output end of the second circulation pump is communicated with the inlet of the fifth inter-stage heater, the outlet of the fifth inter-stage heater is communicated with the input end of the first circulation pump, and the two fifth inter-stage heaters are connected in series on the air return pipeline 46. In operation, the medium is circulated between the air heater and the fifth inter-stage heater by the first circulation pump and the second circulation pump, and the air in the air return pipeline 46 can be cooled.

[0069] In one embodiment of the present application, the expander device comprises a plurality of inter-stage heaters, a plurality of expanders, a high-temperature water tank 10 and a low-temperature water tank 9, and the adjacent two expanders are communicated through the corresponding inter-stage heaters, and the air inlet of the lowest inter-stage heater is communicated with the output end of the liquid-phase air output pipeline 48.

[0070] Specifically, as Figure 1As shown, the expander device includes a first-stage interstage heater 21, a second-stage interstage heater 22, a third-stage interstage heater 23, a fourth-stage interstage heater 24, a first-stage expander 25, a second-stage expander 26, a third-stage expander 27, a fourth-stage expander 28, a high-temperature water tank 10, and a low-temperature water tank 9. The air inlet of the first-stage interstage heater 21 is connected to the output end of the liquid phase air output pipeline 48, and the air outlet of the first-stage interstage heater 21 is connected to the air inlet of the first-stage expander 25. The second-stage interstage heater 22 is located between the first-stage expander 25 and the second-stage expander 26. The air inlet of the second-stage interstage heater 22 is connected to the air outlet of the first-stage expander 25, and the air outlet of the second-stage interstage heater 22 is connected to the air inlet of the second-stage expander 26. The third-stage interstage heater 23 is located between the second-stage expander 26 and the third-stage expander 27. The inlet of the third-stage interstage heater 23 is connected to the outlet of the second-stage expander 26, and the outlet of the third-stage interstage heater 23 is connected to the inlet of the third-stage expander 27. The fourth-stage interstage heater 24 is located between the third-stage expander 27 and the fourth-stage expander 28. The inlet of the fourth-stage interstage heater 24 is connected to the outlet of the third-stage expander 27, and the outlet of the fourth-stage interstage heater 24 is connected to the inlet of the fourth-stage expander 28.

[0071] The inlet of the high-temperature water tank 10 is connected to the outlet of each stage of the interstage cooler, and the outlet of the high-temperature water tank 10 is connected to the inlet of each stage of the interstage heater; the outlet of the low-temperature water tank 9 is connected to the inlet of each stage of the interstage cooler, and the inlet of the low-temperature water tank 9 is connected to the outlet of each stage of the interstage heater.

[0072] Specifically, such as Figure 1 As shown, the inlet of the high-temperature water tank 10 is connected to the outlets of the first-stage intercooler 5, the second-stage intercooler 6, the third-stage intercooler 7, and the fourth-stage intercooler 8. The outlet of the high-temperature water tank 10 is connected to the inlet of the first-stage intercooler 21, the second-stage intercooler 22, the third-stage intercooler 23, and the fourth-stage intercooler 24. The outlet of the low-temperature water tank 9 is connected to the inlet of the first-stage intercooler 5, the second-stage intercooler 6, the third-stage intercooler 7, and the fourth-stage intercooler 8. The inlet of the low-temperature water tank 9 is connected to the outlet of the first-stage intercooler 21, the second-stage intercooler 22, the third-stage intercooler 23, and the fourth-stage intercooler 24.

[0073] In one embodiment of the present application, the expander device further comprises a third liquid air pump 32, a fourth liquid air pump 33 and a first cooler 34, the third liquid air pump 32 is arranged at the liquid outlet of the high-temperature water tank 10, the fourth liquid air pump 33 is arranged at the liquid outlet of the low-temperature water tank 9, and the first cooler 34 is arranged at the liquid inlet of the low-temperature water tank 9, the first cooler 34 is used for cooling the medium output by the multi-stage inter-stage heater, and the cooled medium enters the low-temperature water tank 9 again.

[0074] In one embodiment of the present application, the expander device further comprises a return air pipeline 46 and a second cooler 29, the air inlet end of the return air pipeline 46 is communicated with the air inlet of one of the inter-stage heaters, specifically, the air inlet end of the return air pipeline 46 is communicated with the air inlet of the fourth-stage expander 28, the air outlet end of the return air pipeline 46 is communicated with the rectifying device 30, and the second cooler 29 is connected in series with the return air pipeline 46, the second cooler 29 is used for cooling the air in the return air pipeline 46, so that the temperature of the air reaches a predetermined room temperature.

[0075] In one embodiment of the present application, the expander device further comprises a second connecting pipeline 49 and a Rankine cycle power generation device 47, the liquid inlet end of the second connecting pipeline 49 is communicated with the liquid outlet of the third liquid air pump 32, the liquid outlet end of the second connecting pipeline 49 is communicated with the liquid inlet end of the second cooler 29, and the inter-stage heater of the Rankine cycle power generation device 47 is connected in series with the second connecting pipeline 49. The Rankine cycle power generation device 47 is composed of an inter-stage heater, a stage expander, a circulating pump and a cooler, and the Rankine cycle power generation device 47 is a prior art device in the field, and the specific connection relationship is not described in detail here. Since the compressed heat of the expansion air cannot be completely recovered, if the heat is discharged to the environment, part of the heat will be wasted. Therefore, the Rankine cycle power generation device 47 is added to the power generation unit to utilize the waste heat and improve the round-trip efficiency of the system.

[0076] The working principle of the liquid air energy storage system coupled with the air separation device of the present application is as follows:

[0077] During the valley electricity price period, the valley electricity supply compressor set (the first stage compressor 1, the second stage compressor 2, the third stage compressor 3 and the fourth stage compressor 4) works. The ambient air is purified by the air filter and enters the first stage compressor 1, and is cooled by the pressure water in the first stage intercooler 5. The high pressure room temperature air is purified by the molecular sieve purifier to remove water, carbon dioxide, hydrocarbon and other substances. Then the air is continuously compressed by the following stage compressors. The compression heat is recovered by the pressurized water output from the low temperature water tank 9 in the intercooler of each stage, and the generated high temperature water is stored in the high temperature water tank 10. The air output from the second stage intercooler 6 through the first connecting pipeline 40 enters the first stage cold storage unit 11 to obtain cold energy, and part of the air cooled by the first stage cold storage unit 11 enters the air expander 13 for expansion, and finally enters the rectification device 30. The remaining air cooled by the first stage cold storage unit 11 is cooled and liquefied in the second stage cold storage unit 12, and the liquefied liquid air first enters the air expander 13 for expansion, and then enters the throttle valve 14 for throttling. In the generated gas-liquid mixture, the liquid phase is stored in the liquid air tank 15, and the gas phase air returns to the first stage cold storage unit 11 and the second stage cold storage unit 12 through the gas phase air output pipeline 42 to supplement the compressed air with cold energy. Part of the liquid air in the liquid air tank 15 is extracted, pressurized by the first liquid air pump 16, and sent to the rectification device 30.

[0078] The rectification device 30 has the same structure as the conventional air separation device, and only a brief description is given here. The two raw materials of gas phase and liquid phase enter the high pressure tower for preliminary rectification, and oxygen-rich liquid air and nitrogen are obtained at the bottom and top of the high pressure tower, respectively. The nitrogen is condensed into liquid nitrogen in the condenser evaporator, part of which flows downward as reflux liquid, and the rest is sent to the low pressure tower as reflux liquid. In the middle of the tower, part of the oxygen-poor liquid air is extracted and, together with the oxygen-rich liquid air and liquid nitrogen, enters the subcooler for subcooling. After subcooling, the liquid nitrogen and the oxygen-poor liquid air are throttled to the corresponding pressure and enter the top and middle of the low pressure tower, respectively. The subcooled oxygen-rich liquid air is divided into two parts, one of which is throttled and sent to the middle of the low pressure tower, and the other is throttled and enters the condenser of the crude argon tower to provide a cold source for the crude argon tower, and is heated and enters the low pressure tower. In the low pressure tower, a stream of air is extracted from the argon-rich zone and sent to the crude argon tower for rectification, and argon-rich air is obtained at the top of the crude argon tower, and oxygen-rich liquid air containing essentially no argon is obtained at the bottom, which is returned to the low pressure tower. Finally, liquid oxygen is obtained at the bottom of the low pressure tower and stored in the liquid oxygen tank. Nitrogen is obtained at the top of the low pressure tower and then enters the subcooler. A large amount of dirty nitrogen is produced in the upper part of the low pressure tower, and the dirty nitrogen and the argon-rich air are combined and enter the subcooler to provide cold energy for other streams.

[0079] During the off-peak period, only the first stage compressor 1 and the second stage compressor 2 are running to maintain the stable operation of the rectification device 30. The compressed air enters the first stage cold storage unit 11 and the second stage cold storage unit 12 to recover the cold energy of nitrogen and waste nitrogen. The temperature and pressure of the compressed air from the second stage cold storage unit 12 do not meet the requirements of the rectification device 30, so the compressed air needs to be expanded by the second liquid expander 17 before entering the rectification device 30. At the same time, the liquid air in the liquid air tank 15 is pressurized by the first liquid air pump 16 and enters the rectification device 30 to participate in rectification. During the entire process, the operating flow of the rectification device 30 is consistent with that during the energy storage process, and the products are liquid oxygen, nitrogen and waste nitrogen, the liquid oxygen is stored in the liquid oxygen tank, and the nitrogen and waste nitrogen enter the first stage cold storage unit 11 and the second stage cold storage unit 12 to provide cold energy for the compressed air. During this process, the compressed air is used to provide gas phase raw materials for the rectification device 30, and compared with the energy storage process, the flow of the compressed air is much smaller, so the energy consumption is much lower than that of the energy storage process.

[0080] During the peak period, a large amount of liquid air is used for power generation. The liquid air is pressurized by the second liquid air pump 18 and enters the first air heater 19 and the second air heater 20, and the cold energy thereof is recovered by the propane and methanol-water solution in the heater to obtain high-pressure normal-temperature air. The high-pressure normal-temperature air is recovered by the first stage inter-stage heater 21 to increase the temperature, and then enters the first stage expander 25 to expand, and the expander drives the generator to generate electricity. After three-stage expansion, the pressure of the air approaches the pressure of the rectification device 30, so that a part of the expanded air is supplied to the rectification device 30 through the air return pipeline 46, and the remaining air is heated and then enters the fourth stage expander 28 to expand to normal pressure. The expanded air supplied to the rectification device 30 has a temperature higher than room temperature, and is cooled to room temperature in the second cooler 29 before entering the rectification device 30. In the cold storage unit, the expanded air recovers cold energy from the propane and methanol-water solution, and after reaching the specified temperature requirement, enters the rectification device 30 to participate in rectification.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions described in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; 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

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The air A second air heater (20), the first air heater (19) and the second air heater (20) are connected in series in a liquid phase air output pipeline (48), an input end of the liquid phase air output pipeline (48) is communicated with the liquid air tank (15) through a second liquid air pump (18), and an output end of the liquid phase air output pipeline (48) is communicated with the expander device; the first air heater (19) is communicated with the first stage cold storage unit (11) through a circulating pipeline, and the second air heater (20) is communicated with the second stage cold storage unit (12) through a circulating pipeline.

2. The coupled air separation plant liquid air energy storage system of claim 1, wherein, The cold storage device further comprises: An air expander (13), the liquid phase air input pipeline (41) between the first stage cold storage unit (11) and the second stage cold storage unit (12) is communicated with an input end of the air expander (13), and an output end of the air expander (13) is communicated with the rectification device (30); A second liquid expander (17), the liquid phase air input pipeline (41) between the second stage cold storage unit (12) and the first liquid expander (31) is communicated with an input end of the second liquid expander (17), and an output end of the second liquid expander (17) is communicated with the rectification device (30).

3. The coupled air separation plant liquid air energy storage system of claim 2, wherein, The expander device comprises: A plurality of inter-stage heaters; A plurality of expanders, adjacent two expanders are communicated through a corresponding inter-stage heater, and an air inlet of an inter-stage heater of a lowest stage is communicated with an output end of the liquid phase air output pipeline (48); A high-temperature water tank (10), a liquid inlet of the high-temperature water tank (10) is communicated with a liquid outlet of each inter-stage cooler, and a liquid outlet of the high-temperature water tank (10) is communicated with a liquid inlet of each inter-stage heater; A low-temperature water tank (9), a liquid outlet of the low-temperature water tank (9) is communicated with a liquid inlet of each inter-stage cooler, and a liquid inlet of the low-temperature water tank (9) is communicated with a liquid outlet of each inter-stage heater.

4. The coupled air separation plant liquid air energy storage system of claim 3, wherein, The expander device further comprises: A third liquid air pump (32), the third liquid air pump (32) is arranged at the liquid outlet of the high-temperature water tank (10); A fourth liquid air pump (33), the fourth liquid air pump (33) is arranged at the liquid outlet of the low-temperature water tank (9); A first cooler (34), the first cooler (34) is arranged at the liquid inlet of the low-temperature water tank (9).

5. The coupled air separation plant liquid air energy storage system of claim 4, wherein, The expander device further comprises: A gas return pipeline (46), a gas inlet end of the gas return pipeline (46) is communicated with an air inlet of one of the inter-stage heaters, and a gas outlet end of the gas return pipeline (46) is communicated with the rectification device (30); A second cooler (29), the second cooler (29) is connected in series in the gas return pipeline (46).

6. The coupled air separation plant liquid air energy storage system of claim 5, wherein, The expander device further comprises: A second connecting pipeline (49), a liquid inlet end of the second connecting pipeline (49) is communicated with a liquid outlet of the third liquid air pump (32), and a liquid outlet end of the second connecting pipeline (49) is communicated with a liquid inlet end of the second cooler (29); A Rankine cycle power plant (47) having an inter-stage heater (48) in series with the second connection line (49).

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