Air separation system coupled with liquid air energy storage

Abstract

The present disclosure relates to the technical field of liquefied air energy storage, and particularly relates to a kind of air separation system coupled with liquid air energy storage, comprising air separation unit, liquid air energy storage unit and main heat exchanger.The air separation unit includes rectification assembly and condensation evaporator, the rectification assembly is used to carry out rectification treatment to liquid air to obtain required gas, and the condensation evaporator is used to heat exchange for rectification assembly;Liquid air energy storage unit is used to supply liquid air to rectification assembly and condensation evaporator, and the liquid air after heat exchange by condensation evaporator will be reflowed in rectification assembly;Main heat exchanger is communicated with rectification assembly, for reheat required gas after rectification.The air separation system can effectively reduce the power consumption, reduce the use cost.

Description

Technical Field

[0001] This disclosure relates to the field of liquefied air energy storage technology, and more particularly to an air separation system coupled with liquefied air energy storage. Background Technology

[0002] In the context of new power systems, novel energy storage technologies have become crucial technologies and fundamental equipment for building these systems. They are essential supports for achieving carbon peaking and carbon neutrality goals. Energy storage technologies can store energy during periods of low grid load and output energy during periods of high load to smooth out peak flows and mitigate grid fluctuations; they can also be used as emergency energy sources. Liquid air energy storage technology is a novel compressed air energy storage technology that stores energy in the form of liquid air. This technology offers advantages such as flexible energy coupling, high energy density, flexible storage duration, no capacity decay, environmental friendliness, and long service life.

[0003] Air separation units have extensive applications in chemical, metallurgical, and power industries, producing gases such as oxygen and nitrogen. Cryogenic air separation involves first compressing and cooling air to liquefy it, then separating various gaseous products through a distillation process based on the different boiling points of the gas components. However, existing air separation systems are complex, with numerous high-power-consuming devices, and electricity costs account for approximately 75%-80% of the total power consumption. Significant power consumption occurs in the compression and expansion-cooling sections to obtain qualified gaseous products. The electricity consumed in the compression section is used to produce the raw material compressed air for gaseous product production. The compression system, after compression, precooling, and purification stages, produces qualified compressed air which enters the distillation column of the air separation unit. After liquefaction, distillation, and separation, qualified gaseous or liquid products are obtained. Its expansion and cooling section requires high-pressure compressed air to expand isentropically in the expander to obtain cooling capacity, thereby establishing the distillation conditions for the distillation column in order to obtain the final gaseous and liquid products. The compression section and the expansion and cooling section are high-power-consuming sections of the air separation unit. Therefore, there is an urgent need for an air separation system coupled with liquid air energy storage to solve the problems of high energy consumption and high operating costs of existing air separation units. Utility Model Content

[0004] To address the aforementioned technical problems, this disclosure provides an air separation system coupled with liquid air energy storage.

[0005] This disclosure provides an air separation system coupled with liquid air energy storage, comprising:

[0006] An air separation unit includes a distillation assembly and a condenser-evaporator. The distillation assembly is used to distill liquid air to obtain the desired gas, and the condenser-evaporator is used to exchange heat for the distillation assembly.

[0007] A liquid air energy storage unit is used to supply liquid air to the distillation assembly and the condenser-evaporator, and the liquid air after heat exchange in the condenser-evaporator will flow back into the distillation assembly;

[0008] The main heat exchanger, connected to the distillation assembly, is used to reheat the required gas after distillation.

[0009] Optionally, the distillation assembly includes a two-stage distillation column, which includes an upper distillation column and a lower distillation column that are connected to each other. The condenser-evaporator is disposed in the upper distillation column, and the liquid air energy storage unit is connected to the lower distillation column and the condenser-evaporator.

[0010] Optionally, the lower distillation column has a first liquid air inlet, a second liquid air inlet, a reflux liquid nitrogen inlet, a first nitrogen outlet, an oxygen-enriched liquid air outlet, and a compressed air inlet; the upper distillation column has a liquid nitrogen inlet, a waste nitrogen outlet, an oxygen-enriched liquid air inlet, and an oxygen product outlet, the oxygen product outlet being used to output liquid oxygen or gaseous oxygen; the condenser-evaporator has a first inlet, a first outlet, a second inlet, and a second outlet; the liquid air energy storage unit is connected to the first liquid air inlet and the second inlet, the second liquid air inlet is connected to the second outlet; the oxygen-enriched liquid air outlet is connected to the oxygen-enriched liquid air inlet, the first nitrogen outlet is connected to the first inlet; the first outlet is connected to the liquid nitrogen inlet and the reflux liquid nitrogen inlet; the waste nitrogen outlet is connected to the main heat exchanger via a waste nitrogen output pipeline, and external compressed air is connected to the compressed air inlet via a compressed air input pipeline, and flows into the compressed air inlet after heat exchange in the main heat exchanger.

[0011] Optionally, it also includes a liquid oxygen booster pump and a liquid nitrogen booster pump. The first outlet is connected to the main heat exchanger via a purified nitrogen output pipeline, and the liquid oxygen output from the oxygen product outlet enters the main heat exchanger via a purified oxygen output pipeline. The liquid oxygen booster pump is installed on the purified oxygen output pipeline, and the liquid nitrogen booster pump is installed on the purified nitrogen output pipeline.

[0012] Optionally, the system also includes an oxygen booster and a nitrogen booster. The upper distillation column has a second nitrogen outlet, which is connected to the main heat exchanger via a purified nitrogen output pipeline. The gaseous oxygen output from the oxygen product outlet enters the main heat exchanger via a purified oxygen output pipeline. The oxygen booster is connected to the oxygen output end of the main heat exchanger, and the nitrogen booster is connected to the nitrogen output end of the main heat exchanger.

[0013] Optionally, it also includes a liquid nitrogen storage tank for storing liquid nitrogen and a liquid oxygen storage tank for storing liquid oxygen, wherein the first outlet is connected to the liquid nitrogen storage tank and the oxygen product outlet is connected to the liquid oxygen storage tank.

[0014] Optionally, the liquid air energy storage unit is connected to the main heat exchanger via a liquid air output pipeline. The liquid air energy storage unit can supply liquid air to the main heat exchanger, and the gaseous air generated by the liquid air after heat exchange in the main heat exchanger flows back to the compressed air input pipeline.

[0015] Optionally, it also includes a liquid nitrogen storage tank, and the condenser-evaporator has a first inlet, a first outlet, a second inlet, a second outlet, a third inlet, and a third outlet; the distillation assembly includes a lower distillation column, which has a first liquid air inlet, a second liquid air inlet, a reflux liquid nitrogen inlet, a first nitrogen outlet, an oxygen-enriched liquid air outlet, and a compressed air inlet;

[0016] The liquid air energy storage unit is connected to the first liquid air inlet, the second inlet, and the main heat exchanger. The second liquid air inlet is connected to the second outlet. The first nitrogen outlet is connected to the first inlet and the main heat exchanger. The oxygen-enriched liquid air outlet is connected to the third inlet. The third outlet is connected to the main heat exchanger. The first outlet is connected to the reflux liquid nitrogen inlet and the liquid nitrogen storage tank. The compressed air inlet is connected to the main heat exchanger via a compressed air input pipeline. The liquid air energy storage unit is connected to the main heat exchanger via a liquid air output pipeline. The liquid air energy storage unit can supply liquid air to the main heat exchanger. The gaseous air generated by heat exchange in the main heat exchanger flows back to the compressed air input pipeline.

[0017] Optionally, the liquid air energy storage unit includes a cryogenic air compression liquefaction device, a liquid air storage tank, and a cryogenic delivery pump. The cryogenic air compression liquefaction device is used to produce liquid air. The liquid air storage tank is connected to the cryogenic air compression liquefaction device and the cryogenic delivery pump. The liquid air storage tank is used to store liquid air. The liquid air in the liquid air storage tank is uniformly delivered to the distillation component and the condenser-evaporator via the cryogenic delivery pump.

[0018] Optionally, it may also include a subcooler located upstream of the main heat exchanger, the subcooler being used for heat exchange.

[0019] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0020] The liquid air energy storage unit of this air separation system uses liquid air energy storage technology to generate and store liquid air. This unit can simultaneously supply liquid air to the distillation unit and the condenser-evaporator. A portion of the liquid air from the storage unit flows into the distillation unit of the air separation unit as a clean liquid air feedstock, while the remaining liquid air flows into the condenser-evaporator as a cold source. The liquid air that has been heated by heat exchange in the condenser-evaporator then flows back into the distillation unit, where it is again used as a liquid air feedstock for the air separation unit. This effectively reduces power consumption in the compression and expansion-cooling sections, lowering operating costs. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0022] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system schematic diagram of the air separation system coupled with liquid air energy storage as described in Embodiment 1 of this disclosure;

[0024] Figure 2 This is a system schematic diagram of the air separation system coupled with liquid air energy storage as described in Embodiment 2 of this disclosure;

[0025] Figure 3 This is a system schematic diagram of the air separation system coupled with liquid air energy storage as described in Embodiment 3 of this disclosure;

[0026] Figure 4 This is a system schematic diagram of the air separation system coupled with liquid air energy storage as described in Embodiment 4 of this disclosure.

[0027] in:

[0028] 1. Spatial separation unit;

[0029] 11. Distillation Components; 111. Upper Distillation Column; 1111. Liquid Nitrogen Inlet; 1112. Waste Nitrogen Outlet; 1113. Oxygen-Enriched Liquid Air Inlet; 1114. Oxygen Product Outlet; 1115. Second Nitrogen Outlet; 112. Lower Distillation Column; 1121. First Liquid Air Inlet; 1122. Second Liquid Air Inlet; 1123. Reflux Liquid Nitrogen Inlet; 1124. First Nitrogen Outlet; 1125. Oxygen-Enriched Liquid Air Outlet; 1126. Compressed Air Inlet;

[0030] 12. Condenser-evaporator; 121. First inlet; 122. First outlet; 123. Second inlet; 124. Second outlet; 125. Third inlet; 126. Third outlet;

[0031] 2. Liquid air energy storage unit; 21. Cryogenic air compression liquefaction device; 22. Liquid air storage tank; 23. Cryogenic transfer pump;

[0032] 3. Main heat exchanger;

[0033] 4. Liquid oxygen booster pump; 5. Liquid nitrogen booster pump;

[0034] 6. Oxygen booster; 7. Nitrogen booster;

[0035] 8. Liquid nitrogen storage tank; 9. Liquid oxygen storage tank;

[0036] 10. Subcooler;

[0037] 100. Clean nitrogen output pipeline; 1001. Nitrogen output pipeline; 1002. Liquid nitrogen output pipeline; 101. Clean oxygen output pipeline; 102. Waste nitrogen output pipeline; 103. Compressed air input pipeline; 104. Liquid air output pipeline. Detailed Implementation

[0038] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0039] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0040] Example 1

[0041] Figure 1The air separation system coupled with liquid air energy storage in this embodiment mainly includes an air separation unit 1 and a liquid air energy storage unit 2. The air separation unit 1 includes a distillation assembly 11 and a condenser-evaporator 12. The distillation assembly 11 is used to distill liquid air to obtain the desired gas. The condenser-evaporator 12 is a commonly used device in the art, mainly used for heat exchange of the distillation assembly 11. In this embodiment, the liquid air energy storage unit 2 uses liquid air energy storage technology to generate and store liquid air. The liquid air energy storage unit 2 can simultaneously supply liquid air to both the distillation assembly 11 and the condenser-evaporator 12. A portion of the liquid air in the liquid air energy storage unit 2 flows into the distillation assembly 11 of the air separation unit 1 as a clean liquid air feedstock. The remaining liquid air flows into the condenser-evaporator 12 as a cold source. The liquid air that has been heated by heat exchange in the condenser-evaporator 12 then flows back into the distillation assembly 11, also simultaneously being used as a liquid air feedstock for the air separation unit 1. The main heat exchanger 3 is connected to the distillation assembly 11 and is a heat exchange device for compressed air, liquid nitrogen, liquid oxygen, and waste nitrogen. It is used to cool the compressed air and reheat the liquid nitrogen, liquid oxygen, and waste nitrogen to room temperature. It is used to reheat the required gas after distillation so that the required gas after distillation can be heated to the qualified operating conditions and meet the output conditions.

[0042] It is understood that in this embodiment, the liquid air energy storage unit 2 is used to stably supply liquid air to the air separation unit 1, which in turn performs gas separation. The liquid air energy storage unit 2 uses liquid air energy storage technology to generate and store liquid air. The liquid air obtained by the liquid air energy storage unit 2 during off-peak hours is the same as the clean feed gas required by the air separation unit 1, and it also possesses the low-temperature cooling capacity required for distillation. The cost of liquid air produced by liquefied air energy storage is approximately 50%–80% lower than the electricity cost for obtaining gas in conventional air separation units. By simultaneously allowing the liquid air from the liquid air energy storage unit 2 to flow into both the distillation component 11 and the condenser-evaporator 12, the air separation unit 1 can avoid re-preparing qualified liquid air feedstock. By utilizing the readily available liquid air in the liquid air energy storage unit 2 as the liquid air feedstock for the air separation unit 1, the power consumption of the compression section of the air separation unit 1 is significantly reduced. Furthermore, by utilizing the readily available liquid air in the liquid air energy storage unit 2 as the cooling source for the condenser-evaporator 12, the power consumption of the expansion and cooling section can be reduced. Moreover, the air separation unit 1 does not need to rely on refrigeration devices such as expanders. It can effectively replace the expansion refrigeration method, effectively avoid the failures and shutdowns caused by fluctuations in cooling capacity and reduced reliability of expanders, which would affect the normal operation of the entire air separation unit 1. It can also significantly reduce power consumption, improve the long-term operation capability of the unit, and reduce costs and increase efficiency for gas products.

[0043] It is worth noting that in this embodiment, the air separation unit 1 and the liquid air energy storage unit 2 operate independently and do not participate in the control logic of the two separate devices. This invention can be applied not only to newly built air separation systems but also to the retrofitting of existing systems. It can be applied to processes including, but not limited to, single-high-pressure air separation processes, dual-high-pressure internal compression air separation processes, dual-high-pressure external compression air separation processes, and all-liquid air separation processes. It will not alter the existing rare gas extraction processes of air separation units, such as argon systems, neon-helium systems, and krypton-xenon systems. For retrofitting operations, applying this invention to retrofitted air separation units can adjust the loads of the air separation unit's compression purification system and expansion refrigeration system to maintain them at their optimal operating points. This invention can also be used to adjust the compressor and expander loads according to 70-105% to keep them at their most energy-efficient operating points.

[0044] Furthermore, such as Figure 1 As shown, the distillation assembly 11 in this embodiment is a two-stage distillation column, which includes an upper distillation column 111 and a lower distillation column 112 that are connected to each other. The condenser-evaporator 12 is disposed in the upper distillation column 111, and the liquid air energy storage unit 2 is connected to the lower distillation column 112 and the condenser-evaporator 12.

[0045] The upper distillation column 111, lower distillation column 112, and condenser-evaporator 12 in this embodiment are existing devices in the field. In the lower distillation column 112, after multiple heat exchanges and condensations between liquefied air and cooled compressed air, oxygen-enriched liquid air is obtained at the bottom and qualified nitrogen is obtained at the top. The condenser-evaporator 12 releases cooling energy from liquefied air, which exchanges heat with nitrogen and liquid oxygen before entering the lower distillation column 112 to participate in the lower column distillation process. The pressurized nitrogen rising from the lower distillation column 112 exchanges heat to form liquid nitrogen, which participates in the distillation processes of both the lower and upper distillation columns 112. Liquid oxygen is subcooled after heat exchange with the liquid oxygen at the bottom of the upper distillation column 111. In the upper distillation column 111, rising liquid nitrogen flows down from the top, and oxygen-enriched liquid air enters from the middle, participating in the distillation process. Qualified liquid oxygen is obtained at the bottom of the upper distillation column 111.

[0046] like Figure 1As shown, the liquid air energy storage unit 2 includes a cryogenic air compression liquefaction device 21, a liquid air storage tank 22, and a cryogenic transfer pump 23. The cryogenic air compression liquefaction device 21 is used to produce liquid air. It is an existing device, and its main principle is to utilize the liquid air obtained from surplus power from the grid (off-peak electricity) or renewable energy generation (wind power, photovoltaic power, etc.). The generated liquid air contains no water or carbon dioxide and can be directly used as the feed gas for the distillation component 11, as well as as the cold source for the condenser-evaporator 12, providing the required cooling capacity for the distillation component 11. The liquid air storage tank 22 serves as a storage device for liquid air. The liquid air generated by the cryogenic air compression liquefaction device 21 is collected and stored in the liquid air storage tank 22. The cryogenic transfer pump 23 is used to transport the liquid air in the liquid air storage tank 22 to the lower distillation column 112 and the condenser-evaporator 12, so as to deliver liquid air that meets the temperature and pressure requirements to the lower distillation column 112.

[0047] like Figure 1 As shown, this embodiment 1 is an internal compression process scheme for an air separation system, mainly used to output gaseous oxygen and gaseous nitrogen.

[0048] Specifically, the lower distillation column 112 has a first liquid air inlet 1121, a second liquid air inlet 1122, a reflux liquid nitrogen inlet 1123, a first nitrogen outlet 1124, an oxygen-enriched liquid air outlet 1125, and a compressed air inlet 1126. The upper distillation column 111 has a liquid nitrogen inlet 1111, a waste nitrogen outlet 1112, an oxygen-enriched liquid air inlet 1113, and an oxygen product outlet 1114. In this embodiment, the oxygen product outlet 1114 is used to output liquid oxygen after distillation. The condenser-evaporator 12 has a first inlet 121, a first outlet 122, a second inlet 123, and a second outlet 124. The output end of the cryogenic transfer pump 23 is connected to the first liquid air inlet 1121 and the second inlet 123. The liquid air output by the cryogenic transfer pump 23 flows into the lower distillation column 112 as the feed gas for distillation, which can regulate the cooling balance and feed balance of the lower distillation column 112. On the other hand, it serves as the cold source for the condenser-evaporator 12, providing the required cooling capacity. The second liquid air inlet 1122 is connected to the second outlet 124. Liquid air entering the condenser-evaporator 12 through the second inlet 123 releases its cooling capacity and then flows from the second outlet 124 back to the second liquid air inlet 1122 to participate in the distillation of the lower distillation column 112. After distillation in the lower distillation column 112, oxygen-rich liquid air is formed at the bottom and pressurized nitrogen is formed at the top. Optionally, this embodiment also includes a subcooler 10. The subcooler 10 is a commonly used device in the field. It is located upstream of the main heat exchanger 3 and is also used for cooling capacity exchange. It is a heat exchange device for liquid nitrogen, subcooled liquid nitrogen, oxygen-rich liquid, and waste nitrogen gas to complete the heat exchange between the throttled rising liquid nitrogen and rising oxygen-rich liquid and the subcooled liquid nitrogen product and waste nitrogen gas in the subcooler 10. Figure 1As shown, the oxygen-enriched liquid air outlet 1125 is connected to the oxygen-enriched liquid air inlet 1113. The oxygen-enriched liquid air formed at the bottom of the lower distillation column 112 is extracted from the oxygen-enriched liquid air outlet 1125, and after heat exchange in the cooler 10, it is cooled by throttling before participating in the upper column distillation. After distillation in the lower distillation column 112, the pressurized nitrogen formed at its top is discharged through the first nitrogen outlet 1124, which is connected to the first inlet 121. The pressurized nitrogen can flow into the condenser-evaporator 12 through the first inlet 121, and the liquid nitrogen formed by cold exchange flows out through the first outlet 122. In this embodiment, the first outlet 122 is connected to the liquid nitrogen inlet 1111 and the reflux liquid nitrogen inlet 1123. Part of the liquid nitrogen flowing out of the first outlet 122 flows back to the top of the lower distillation column 112 through the reflux liquid nitrogen inlet 1123 to participate in the distillation of the lower distillation column 112. The other part, after heat exchange in the subcooler 10, flows into the upper distillation column 111 through the liquid nitrogen inlet 1111 to participate in the distillation of the upper distillation column 111. Furthermore, the first outlet 122 is also connected to the main heat exchanger 3 through the clean nitrogen output pipeline 100. The liquid nitrogen that does not flow into the upper distillation column 111 and the lower distillation column 112 is uniformly input to the main heat exchanger 3 through the clean nitrogen output pipeline 100. After heat exchange in the main heat exchanger 3, it absorbs heat to form nitrogen gas, which is then output externally. Optionally, a liquid nitrogen booster pump 5 is installed on the purified nitrogen output pipeline 100 to transport liquid nitrogen at pump pressure, thereby delivering qualified liquid nitrogen products after distillation to gas-using devices outside the air separation unit that meet the required pressure and temperature requirements. Further, the waste nitrogen gas at the top of the upper distillation column 111 is discharged through the waste nitrogen outlet 1112, participates in heat exchange in the subcooler 10, releases some of its cooling capacity, and enters the main heat exchanger 3 through the waste nitrogen output pipeline 102. After participating in heat exchange in the main heat exchanger 3, it releases most of its cooling capacity and is then discharged. Finally, it is used as the regeneration heating feed gas in the air separation unit's purification unit, as chilled water in the pre-cooling unit's air-cooled tower, or as other cooling equipment before being discharged into the atmosphere. Furthermore, the high-purity liquid oxygen formed after distillation at the bottom of the upper distillation column 111 is discharged through the oxygen product outlet 1114. The liquid oxygen output from the oxygen product outlet 1114 enters the main heat exchanger 3 through the purified oxygen output pipeline 101. The liquid oxygen booster pump 4 is installed on the purified oxygen output pipeline 101 to pump the liquid oxygen. After distillation, the qualified liquid oxygen product is delivered to the gas-using devices outside the air separation unit to meet the required pressure and temperature. The liquid oxygen output from the oxygen product outlet 1114 exchanges heat with other streams in the main heat exchanger 3, releasing a large amount of cold energy to form gaseous oxygen before flowing out, completing the complete process of pressurized oxygen distillation, pressurization, reheating, and external delivery. External compressed air is connected to compressed air inlet 1126 via compressed air input pipeline 103. In this embodiment, ambient temperature external compressed air is input into the main heat exchanger 3 as a heat source. After absorbing cold energy in the main heat exchanger 3, the external compressed air enters the lower distillation column 112 through compressed air inlet 1126 to vaporize the two streams entering from the first liquid air inlet 1121 and the second liquid air inlet 1122, so that oxygen-rich liquid air is formed downwards and high-purity nitrogen is formed upwards in the lower distillation column 112, and finally the distillation working condition is established.

[0049] Example 2

[0050] Figure 2 The figure shown is an air separation system coupled with liquid air energy storage in this embodiment 2. This embodiment is an external compression process scheme for the air separation system, which is mainly used to output gaseous oxygen and gaseous nitrogen.

[0051] The difference between the internal compression process scheme in Example 1 and the external compression process scheme in Example 2 is that the liquid oxygen in the former is discharged in large quantities at the bottom of the upper distillation column 111, resulting in greater cold loss and a larger demand for cooling capacity. In contrast, in Example 2, the main products discharged from the upper distillation column 111 are gaseous oxygen and gaseous nitrogen, and a large amount of cooling capacity is retained in the upper distillation column 111.

[0052] Specifically, Embodiment 2 includes a cryogenic air compression liquefaction device 21, a liquid air storage tank 22, a cryogenic transfer pump 23, a subcooler 10, an upper distillation column 111, a lower distillation column 112, a main heat exchanger 3, an oxygen booster 6, and a nitrogen booster 7. The lower distillation column 112 has a first liquid air inlet 1121, a second liquid air inlet 1122, a reflux liquid nitrogen inlet 1123, a first nitrogen outlet 1124, an oxygen-enriched liquid air outlet 1125, and a compressed air inlet 1126. The upper distillation column 111 has a liquid nitrogen inlet 1111, a waste nitrogen outlet 1112, an oxygen-enriched liquid air inlet 1113, an oxygen product outlet 1114, and a second nitrogen outlet 1115. Notably, the oxygen product outlet 1114 is used to output distilled gaseous oxygen, and the second nitrogen outlet 1115 is used to output distilled gaseous nitrogen. The condenser-evaporator 12 also has a first inlet 121, a first outlet 122, a second inlet 123, and a second outlet 124. The output end of the cryogenic transfer pump 23 is connected to the first liquid air inlet 1121 and the second inlet 123. The liquid air output by the cryogenic transfer pump 23 flows into the lower distillation column 112 as the feed gas for distillation, which can regulate the cold balance and feed-discharge balance of the lower distillation column 112. On the other hand, it serves as the cold source for the condenser-evaporator 12, providing the required cooling capacity. The second liquid air inlet 1122 is connected to the second outlet 124. The liquid air entering the condenser-evaporator 12 through the second inlet 123 releases its cooling capacity and then flows from the second outlet 124 back to the second liquid air inlet 1122 to participate in the distillation of the lower distillation column 112. After distillation in the lower distillation column 112, oxygen-rich liquid air is formed at the bottom and pressurized nitrogen is formed at the top. Optionally, this embodiment also includes an undercooler 10. Figure 1As shown, the oxygen-enriched liquid air outlet 1125 is connected to the oxygen-enriched liquid air inlet 1113. The oxygen-enriched liquid air formed at the bottom of the lower distillation column 112 is extracted from the oxygen-enriched liquid air outlet 1125, and after heat exchange in the cooler 10, it is cooled by throttling before participating in the distillation of the upper distillation column 111. After distillation in the lower distillation column 112, the pressurized nitrogen formed at its top is discharged through the first nitrogen outlet 1124, which is connected to the first inlet 121. The pressurized nitrogen can flow into the condenser-evaporator 12 through the first inlet 121, and the liquid nitrogen formed by cold exchange flows out through the first outlet 122. In this embodiment, the first outlet 122 is connected to the liquid nitrogen inlet 1111 and the reflux liquid nitrogen inlet 1123. A portion of the liquid nitrogen flowing out of the first outlet 122 flows back to the top of the lower distillation column 112 via the reflux liquid nitrogen inlet 1123 to participate in the distillation of the lower distillation column 112. The other portion, after heat exchange in the subcooler 10, flows into the upper distillation column 111 via the liquid nitrogen inlet 1111 to participate in the distillation of the upper distillation column 111. Further, this embodiment includes an oxygen booster 6 and a nitrogen booster 7. The oxygen booster 6 completes the process of delivering qualified oxygen products after distillation, which are then reheated in the main heat exchanger 3 and pressurized to meet the required pressure and temperature. The nitrogen booster 7 completes the process of delivering qualified nitrogen products after distillation, which are then reheated in the main heat exchanger 3 and pressurized to meet the required pressure and temperature. The second nitrogen outlet 1115 is connected to the main heat exchanger 3 via the purified nitrogen output pipeline 100. The gaseous oxygen output from the oxygen product outlet 1114 enters the main heat exchanger 3 via the purified oxygen output pipeline 101. The oxygen booster 6 is connected to the oxygen output end of the main heat exchanger 3, and the nitrogen booster 7 is connected to the nitrogen output end of the main heat exchanger 3. The high-purity nitrogen produced by the distillation in the upper distillation column 111 is discharged from the top second nitrogen outlet 1115. After the subcooler 10 releases its cooling capacity, it enters the main heat exchanger 3. After the main heat exchanger 3 releases its cooling capacity, it enters the nitrogen booster 7, and after being pressurized by the nitrogen booster 7, it is discharged, completing the complete process of nitrogen distillation, reheating, pressurization, and external delivery. Meanwhile, the high-purity gaseous oxygen formed by distillation at the bottom of the upper distillation column 111 flows out of the oxygen product outlet 1114 and enters the main heat exchanger 3. After heat exchange in the main heat exchanger 3, it flows out into the oxygen booster 6 and is discharged after being pressurized by the oxygen booster 6, thus completing the complete process of oxygen distillation, reheating, pressurization and external delivery. The rest is the same as in Example 1, and will not be described again in this example.

[0053] Example 3

[0054] Figure 3 The image shows an air separation system coupled with liquid air energy storage in Embodiment 3. This embodiment is a full liquid process scheme for the air separation system, mainly used to output liquid oxygen and liquid nitrogen. All output products are liquids. Compared with the traditional air separation process, since liquid air directly enters the lower column to participate in distillation and provides a large amount of cooling capacity and the required raw material gas, it can replace the traditional full liquid air separation process such as direct air expansion and refrigeration, air circulation expansion and refrigeration, and nitrogen expansion and refrigeration.

[0055] The difference between this embodiment 3 and embodiment 1 is that, in this embodiment 3, the liquid nitrogen and liquid oxygen output from the upper distillation column 111 are stored in the liquid nitrogen storage tank 8 and the liquid oxygen storage tank 9, respectively, and are not output to the outside. In addition, the cryogenic transfer pump 23 can also simultaneously pump liquid air to the main heat exchanger 3, so that the liquid air flowing into the main heat exchanger 3 exchanges heat with the compressed air flowing into the main heat exchanger 3, and the gaseous air generated by the heat exchange flows back to the compressed air input pipeline 103 and enters the lower distillation column 112.

[0056] Specifically, such as Figure 3 As shown, Embodiment 3 mainly includes a cryogenic air compression liquefaction device 21, a liquid air storage tank 22, a cryogenic transfer pump 23, an upper distillation column 111, a lower distillation column 112, a liquid nitrogen storage tank 8, a liquid oxygen storage tank 9, a subcooler 10, and a main heat exchanger 3. The lower distillation column 112 has a first liquid air inlet 1121, a second liquid air inlet 1122, a reflux liquid nitrogen inlet 1123, a first nitrogen outlet 1124, an oxygen-enriched liquid air outlet 1125, and a compressed air inlet 1126. The upper distillation column 111 has a liquid nitrogen inlet 1111, a waste nitrogen outlet 1112, an oxygen-enriched liquid air inlet 1113, and an oxygen product outlet 1114, which is used to output liquid oxygen. The condenser-evaporator 12 also has a first inlet 121, a first outlet 122, a second inlet 123, and a second outlet 124. The liquid air boosted by the cryogenic transfer pump 23 is divided into three streams. One stream enters through the second inlet 123 of the condenser evaporator 12 as a cold source; another stream enters the lower distillation column 112 through the first liquid air inlet 1121; and the third stream flows directly into the main heat exchanger 3 through the liquid air output line 104. The liquid air entering the main heat exchanger 3 exchanges heat with the compressed air flowing into the main heat exchanger 3, and the gaseous air generated by the heat exchange flows back to the lower distillation column 112 through the compressed air input line 103 to increase the flow rate of the compressed air in the compressed air input line 103. Simultaneously, the liquid nitrogen output from the first outlet 122 is divided into three parts: one part flows back to the top of the lower distillation column 112 via the reflux liquid nitrogen inlet 1123 to participate in the distillation of the lower distillation column 112; another part, after heat exchange in the subcooler 10, flows into the upper distillation column 111 via the liquid nitrogen inlet 1111 to participate in the distillation of the upper distillation column 111; the remaining part flows into the liquid nitrogen storage tank 8 via the clean nitrogen output pipeline 100, completing the complete process of liquid nitrogen distillation, extraction, and storage. Meanwhile, the high-purity liquid oxygen formed after distillation at the bottom of the upper distillation column 111 flows out from the oxygen product outlet 1114, and after the flow rate is controlled by the regulating valve, flows into the liquid oxygen storage tank 9, completing the complete process of liquid oxygen distillation, extraction, and storage. The remaining parts not mentioned are the same as in Example 1, and will not be repeated in this example.

[0057] Example 4

[0058] Figure 4The image shows an air separation system coupled with liquid air energy storage in Embodiment 4. This embodiment is a single-high-pressure gas-liquid process scheme for the air separation system, mainly used to output gaseous nitrogen and liquid nitrogen. Unlike traditional single-high-pressure air separation process units, the cooling capacity is entirely provided by liquid air, and wide load adjustment is possible in the extraction of nitrogen and liquid nitrogen products.

[0059] Specifically, such as Figure 4 As shown, it mainly includes a cryogenic air compression liquefaction device 21, a liquid air storage tank 22, a cryogenic transfer pump 23, a lower distillation column 112, a liquid nitrogen storage tank 8, a condenser-evaporator 12, and a main heat exchanger 3. It is worth noting that this fourth embodiment uses only one distillation column; for ease of understanding and consistency with the preceding text, this distillation column is referred to as the lower distillation column 112 in this embodiment. The condenser-evaporator 12 has a first inlet 121, a first outlet 122, a second inlet 123, a second outlet 124, a third inlet 125, and a third outlet 126. The lower distillation column 112 has a first liquid air inlet 1121, a second liquid air inlet 1122, a reflux liquid nitrogen inlet 1123, a first nitrogen outlet 1124, an oxygen-enriched liquid air outlet 1125, and a compressed air inlet 1126; the liquid air energy storage unit 2 includes a cryogenic air compression liquefaction device 21, a liquid air storage tank 22, and a cryogenic transfer pump 23 connected in sequence, and the cryogenic transfer pump 23 is connected to the first liquid air inlet 1121, the second inlet 123, and the main heat exchanger 3. The liquid air boosted by the cryogenic transfer pump 23 is divided into three streams. One stream enters through the second inlet 123 of the condenser evaporator 12 as a cold source; another stream enters the lower distillation column 112 through the first liquid air inlet 1121; and the third stream flows directly into the main heat exchanger 3 through the liquid air output line 104. The liquid air entering the main heat exchanger 3 exchanges heat with the compressed air flowing into the main heat exchanger 3, and the gaseous air generated by the heat exchange flows back to the lower distillation column 112 through the compressed air input line 103 to increase the flow rate of the compressed air in the compressed air input line 103.

[0060] After distillation in the lower distillation column 112, the pressurized nitrogen at the top is discharged through the first nitrogen outlet 1124. Part of it enters the condenser-evaporator 12 through the first inlet 121, and the other part flows into the main heat exchanger 3 through the nitrogen output pipeline 1001 for reheating and then is sent out, completing the complete process of nitrogen distillation, reheating, and external delivery. Nitrogen extraction can be adjusted under a wide load range of 0-100%. Furthermore, the liquid nitrogen output through the first outlet 122 is divided into two parts: one part flows back to the top of the lower distillation column 112 through the reflux liquid nitrogen inlet 1123 to participate in the distillation of the lower distillation column 112, establishing a distillation condition with the rising gas in the lower distillation column 112, and obtaining high-purity nitrogen at the top of the distillation column and oxygen-rich liquid air at the bottom; the other part flows into the liquid nitrogen storage tank 8 through the liquid nitrogen output pipeline 1002, completing the complete process of liquid nitrogen distillation, extraction, and storage. Simultaneously, after distillation in the lower distillation column 112, oxygen-rich liquid air is formed at the bottom. This liquid air flows into the condenser-evaporator 12 through the oxygen-rich liquid air outlet 1125 and the third inlet 125. In the condenser-evaporator 12, the oxygen-rich liquid air exchanges heat with liquid air and waste nitrogen, evaporating to form waste nitrogen, which enters the main heat exchanger 3 through the third outlet 126. In the main heat exchanger 3, it exchanges heat with compressed air and nitrogen, releasing a large amount of cooling energy before being discharged. Compressed air required to participate in the lower distillation column 112 enters the main heat exchanger 3. After absorbing cooling energy in the main heat exchanger 3, the compressed air enters the lower distillation column 112 through the compressed air input pipeline 103 to vaporize the two streams flowing from the first liquid air inlet 1121 and the second liquid air inlet 1122. This process creates oxygen-rich liquid air downwards and high-purity nitrogen upwards within the lower distillation column 112, ultimately establishing the distillation operation.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0062] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An air separation system coupled with liquid air energy storage, characterized in that, include: An air separation unit (1) includes a distillation assembly (11) and a condenser-evaporator (12). The distillation assembly (11) is used to distill liquid air to obtain the desired gas, and the condenser-evaporator (12) is used to exchange heat for the distillation assembly (11). The liquid air energy storage unit (2) is used to supply liquid air to the distillation assembly (11) and the condenser-evaporator (12), and the liquid air after heat exchange by the condenser-evaporator (12) will flow back into the distillation assembly (11); The main heat exchanger (3) is connected to the distillation assembly (11) and is used to reheat the gas required after distillation.

2. The air separation system with coupled liquid air energy storage according to claim 1, characterized in that, The distillation assembly (11) includes a two-stage distillation column, which includes an upper distillation column (111) and a lower distillation column (112) that are connected to each other. The condenser-evaporator (12) is disposed in the upper distillation column (111). The liquid air energy storage unit (2) is connected to the lower distillation column (112) and the condenser-evaporator (12).

3. The air separation system with coupled liquid air energy storage according to claim 2, characterized in that, The lower distillation column (112) has a first liquid air inlet (1121), a second liquid air inlet (1122), a reflux liquid nitrogen inlet (1123), a first nitrogen outlet (1124), an oxygen-enriched liquid air outlet (1125), and a compressed air inlet (1126); the upper distillation column (111) has a liquid nitrogen inlet (1111), a waste nitrogen outlet (1112), an oxygen-enriched liquid air inlet (1113), and an oxygen product outlet (1114), the oxygen product outlet (1114) being used to output liquid oxygen or gaseous oxygen; the condenser-evaporator (12) has a first inlet (121), a first outlet (122), a second inlet (123), and a second outlet (124); the liquid air energy storage unit (2) is connected to the first liquid air inlet (1125) and the first liquid air inlet (1126). The first nitrogen outlet (1124) is connected to the first inlet (121) and the second inlet (123); the second liquid air inlet (1122) is connected to the second outlet (124); the oxygen-enriched liquid air outlet (1125) is connected to the oxygen-enriched liquid air inlet (1113); the first nitrogen outlet (1124) is connected to the first inlet (121); the first outlet (122) is connected to the liquid nitrogen inlet (1111) and the return liquid nitrogen inlet (1123); the waste nitrogen outlet (1112) is connected to the main heat exchanger (3) via the waste nitrogen output pipeline (102); external compressed air is connected to the compressed air inlet (1126) via the compressed air input pipeline (103), and flows into the compressed air inlet (1126) after heat exchange by the main heat exchanger (3).

4. The air separation system with coupled liquid air energy storage according to claim 3, characterized in that, It also includes a liquid oxygen booster pump (4) and a liquid nitrogen booster pump (5). The first outlet (122) is connected to the main heat exchanger (3) via a clean nitrogen output pipeline (100). The liquid oxygen output from the oxygen product outlet (1114) enters the main heat exchanger (3) via a clean oxygen output pipeline (101). The liquid oxygen booster pump (4) is installed on the clean oxygen output pipeline (101), and the liquid nitrogen booster pump (5) is installed on the clean nitrogen output pipeline (100).

5. The air separation system coupled with liquid air energy storage according to claim 3, characterized in that, It also includes an oxygen booster (6) and a nitrogen booster (7). The upper distillation column (111) has a second nitrogen outlet (1115). The second nitrogen outlet (1115) is connected to the main heat exchanger (3) via a clean nitrogen output pipeline (100). The gaseous oxygen output from the oxygen product outlet (1114) enters the main heat exchanger (3) via a clean oxygen output pipeline (101). The oxygen booster (6) is connected to the oxygen output end of the main heat exchanger (3), and the nitrogen booster (7) is connected to the nitrogen output end of the main heat exchanger (3).

6. The air separation system coupled with liquid air energy storage according to claim 3, characterized in that, It also includes a liquid nitrogen storage tank (8) for storing liquid nitrogen and a liquid oxygen storage tank (9) for storing liquid oxygen. The first outlet (122) is connected to the liquid nitrogen storage tank (8), and the oxygen product outlet (1114) is connected to the liquid oxygen storage tank (9).

7. The air separation system coupled with liquid air energy storage according to claim 6, characterized in that, The liquid air energy storage unit (2) is connected to the main heat exchanger (3) via the liquid air output pipeline (104). The liquid air energy storage unit (2) can supply liquid air to the main heat exchanger (3). The gaseous air generated by the liquid air through the main heat exchanger (3) flows back to the compressed air input pipeline (103).

8. The air separation system coupled with liquid air energy storage according to claim 1, characterized in that, It also includes a liquid nitrogen storage tank (8), and the condenser-evaporator (12) has a first inlet (121), a first outlet (122), a second inlet (123), a second outlet (124), a third inlet (125), and a third outlet (126); the distillation assembly (11) includes a lower distillation column (112), which has a first liquid air inlet (1121), a second liquid air inlet (1122), a reflux liquid nitrogen inlet (1123), a first nitrogen outlet (1124), an oxygen-enriched liquid air outlet (1125), and a compressed air inlet (1126); The liquid air energy storage unit (2) is connected to the first liquid air inlet (1121), the second inlet (123), and the main heat exchanger (3). The second liquid air inlet (1122) is connected to the second outlet (124). The first nitrogen outlet (1124) is connected to the first inlet (121) and the main heat exchanger (3). The oxygen-enriched liquid air outlet (1125) is connected to the third inlet (125). The third outlet (126) is connected to the main heat exchanger (3). The first outlet... (122) is connected to the return liquid nitrogen inlet (1123) and the liquid nitrogen storage tank (8). The compressed air inlet (1126) is connected to the main heat exchanger (3) via the compressed air input pipeline (103). The liquid air energy storage unit (2) is connected to the main heat exchanger (3) via the liquid air output pipeline (104). The liquid air energy storage unit (2) can supply liquid air to the main heat exchanger (3). The gaseous air generated by the liquid air heat exchanger (3) flows back to the compressed air input pipeline (103).

9. The air separation system with coupled liquid air energy storage according to any one of claims 1-8, characterized in that, The liquid air energy storage unit (2) includes a cryogenic air compression liquefaction device (21), a liquid air storage tank (22), and a cryogenic delivery pump (23). The cryogenic air compression liquefaction device (21) is used to produce liquid air. The liquid air storage tank (22) is connected to the cryogenic air compression liquefaction device (21) and the cryogenic delivery pump (23). The liquid air storage tank (22) is used to store liquid air. The liquid air in the liquid air storage tank (22) is uniformly delivered to the distillation component (11) and the condenser-evaporator (12) by the cryogenic delivery pump (23).

10. The air separation system with coupled liquid air energy storage according to any one of claims 2-7, characterized in that, It also includes a subcooler (10) located upstream of the main heat exchanger (3), the subcooler (10) being used for heat exchange.

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