Large-capacity process gas peak shaving operation system and method based on liquid air storage

Abstract

This invention discloses a large-capacity process gas peak-shaving operation system and method based on liquid air storage. The system includes an air liquefaction unit and an air vaporization unit. During off-peak electricity demand periods, the air liquefaction unit operates: ambient air is compressed and purified, then enters a stepped-temperature cold storage tank, a constant-temperature cold storage tank, and a phase-change cold storage tank for progressive cooling, resulting in complete liquefaction of the air and storage at low pressure. During peak electricity demand periods, the air vaporization unit operates: liquid air is depressurized and cooled through a pressure reducing valve, then vaporized step-by-step through the phase-change cold storage tank, the constant-temperature cold storage tank, and the stepped-temperature cold storage tank, with the vaporized cold energy stored in stages and supplied to the process gas. This invention achieves peak-shaving operation of process gas by storing liquid during off-peak periods and supplying gas during peak periods, reducing system operating costs. Furthermore, by adjusting the operating pressure of the air liquefaction and vaporization units, 100% gas liquefaction is achieved, reducing system size and investment costs.

Description

Technical Field

[0001] This invention belongs to the field of liquid air technology, and particularly relates to a large-capacity process gas peak-shaving operation system and method based on liquid air storage. Background Technology

[0002] With the continuous expansion of industrial production scale, the demand for process gases in fields such as steel, chemical, metallurgy, and semiconductor manufacturing is constantly increasing. Currently, the industrial sector often uses compressed air storage to achieve peak shaving of process gases. This involves using compressors to compress and store air during off-peak electricity hours and releasing the compressed air during peak electricity hours to meet the gas supply needs at different times.

[0003] However, when using compressed air as the storage medium for large-scale process gas peak shaving, the amount of gas that can be stored per unit volume is relatively low, limiting the system's storage capacity. When industrial production requires large-scale, long-term continuous gas supply, large-capacity gas storage devices or multiple sets of gas storage equipment need to be constructed, which not only increases the system's footprint but also significantly raises equipment investment costs. Furthermore, due to the large pressure changes during gas expansion, the stability of the gas supply process is easily affected. Therefore, traditional compressed air storage methods suffer from problems such as large equipment size, high operating costs, and insufficient system flexibility when meeting large-scale process gas peak shaving needs.

[0004] Liquid air is characterized by high density, low storage pressure, and large gas storage capacity per unit volume. Compared with compressed air storage, it can significantly increase gas storage capacity and reduce the size of storage equipment. Therefore, liquefying air for storage and then releasing it as process gas through vaporization during peak electricity demand periods fully leverages the advantages of high-density liquid air storage. This provides a new technological approach to solving the problem of peak shaving for large-capacity process gases, enabling efficient, stable, and low-cost peak-shaving operation. Summary of the Invention

[0005] This invention aims to solve the key technical problems existing in the storage of large-capacity process gases using compressed air, such as low energy density, large system scale, high investment cost, and low heat transfer efficiency of liquid air during storage and release. The goal is to achieve a large-capacity process gas peak-shaving operation system and method based on liquid air storage with higher energy density and better economic efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a large-capacity process gas peak-shaving operation system based on liquid air storage, comprising:

[0007] An air liquefaction unit is used to purify and compress outside air, then liquefy it by cooling it in three stages through three cold storage tanks, and finally output it to an air vaporization unit; wherein, the air liquefaction unit includes a multi-stage compressor, multiple coolers, a distributor, a water pump, a heater, an adsorption tower and a desorption tower arranged in series;

[0008] An air vaporization unit is used to vaporize compressed and liquefied liquid air in stages through three cold storage tanks; wherein, the air vaporization unit includes a liquid air tank, a pressure reducing valve, a phase change cold storage tank, a constant temperature cold storage tank, and an inclined temperature cold storage tank;

[0009] The air liquefaction unit and the air vaporization unit share the inclined temperature cold storage tank, the constant temperature cold storage tank, and the phase change cold storage tank.

[0010] Preferably, the multi-stage compressor includes a first compressor, a second compressor, and a third compressor; the multiple coolers include a first cooler, a second cooler, and a third cooler; the input end of the first compressor is used to input ambient air, the output end of the first compressor is connected to the first input end of the first cooler, the first output end of the first cooler is connected to the input end of the second compressor, the output end of the second compressor is connected to the first input end of the second cooler, the first output end of the second cooler is connected to the input end of the adsorption tower, the output end of the adsorption tower is connected to the input end of the distributor, and the first output end of the distributor is connected to the input end of the third compressor; the output end of the third compressor is connected to the first input end of the third cooler, the first output end of the third cooler is connected to the first input end of the inclined temperature cold storage tank, the first output end of the inclined temperature cold storage tank is connected to the first input end of the constant temperature cold storage tank, the first output end of the constant temperature cold storage tank is connected to the first input end of the phase change cold storage tank, and the first output end of the phase change cold storage tank serves as the output end of the air liquefaction unit and is connected to the input end of the liquid air tank;

[0011] The second output terminals of the first cooler, the second output terminals of the second cooler, and the second output terminals of the third cooler are connected to the input terminal of the water pump. The output terminal of the water pump is connected to the second input terminal of the heater. The second output terminal of the heater is connected to the second input terminals of the first cooler, the second input terminal of the second cooler, and the second input terminal of the third cooler. The second output terminal of the distributor is connected to the first input terminal of the heater. The first output terminal of the heater is connected to the input terminal of the desorption tower.

[0012] Preferably, the input end of the liquid air tank is connected to the first output end of the phase change cold storage tank as the input end of the air vaporization unit, the output end of the liquid air tank is connected to the input end of the pressure reducing valve, the output end of the pressure reducing valve is connected to the second input end of the phase change cold storage tank, the second output end of the phase change cold storage tank is connected to the second input end of the constant temperature cold storage tank, and the second output end of the constant temperature cold storage tank is connected to the second input end of the inclined temperature cold storage tank.

[0013] Preferably, in the air liquefaction unit, the ambient air is pressurized by a multi-stage compressor arranged in series and then cooled by multiple coolers. After that, it enters a slanted-temperature cold storage tank, a constant-temperature cold storage tank, and a phase-change cold storage tank in sequence to cool down step by step. All the air is liquefied and stored in a low-pressure state.

[0014] Preferably, during the air liquefaction process, the heat of compression generated by air compression is used by the heater to provide thermal energy for heating the diverted gas, and the generated high-temperature gas is used in the desorption tower.

[0015] Preferably, the liquid air in the air vaporization unit is output from the liquid air tank, depressurized and cooled by a pressure reducing valve, and then vaporized in stages through a phase change cold storage tank, a constant temperature cold storage tank and an inclined temperature cold storage tank before being supplied as process gas.

[0016] The present invention also provides a large-capacity process gas peak shaving operation method based on liquid air storage. The method is implemented using the above-mentioned large-capacity process gas peak shaving operation system based on liquid air storage, and the method includes an air liquefaction method and an air vaporization method.

[0017] During off-peak hours, the air liquefaction unit operates: after the ambient air is compressed and purified, it enters the inclined temperature cold storage tank, the constant temperature cold storage tank and the phase change cold storage tank for gradual cooling. The air is completely liquefied and stored in a low-pressure state.

[0018] During peak electricity consumption periods, the air vaporization unit operates: liquid air is depressurized and cooled through a pressure reducing valve to further increase low-temperature cold energy. It is then vaporized in stages through a phase change cold storage tank, a constant temperature cold storage tank, and an inclined temperature cold storage tank, and the vaporized cold energy is stored in stages to supply process gases.

[0019] By adopting the above technical solution: This invention achieves the air liquefaction temperature and improves the yield by adjusting the operating pressure of the air liquefaction unit and the air vaporization unit. The inclined-temperature cold storage tank, the constant-temperature cold storage tank, and the phase-change cold storage tank are filled with cold energy of different grades. During the air liquefaction process, pure air sequentially enters the inclined-temperature cold storage tank, the constant-temperature cold storage tank, and the phase-change cold storage tank, utilizing the cold energy step by step before outputting liquid air. During the air vaporization process, the liquid air sequentially enters the phase-change cold storage tank, the constant-temperature cold storage tank, and the inclined-temperature cold storage tank before outputting process gas, forming a reversible cycle.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention uses liquid air instead of traditional compressed air as the process gas storage medium, utilizing the high-density storage characteristics of liquid air to achieve large-capacity gas storage in a relatively small volume. Compared with compressed air storage methods, this significantly reduces the size of the gas storage equipment and the floor space required.

[0022] 2. This invention enables complete air liquefaction by adjusting the operating pressure of the air liquefaction unit and the air vaporization unit, achieving 100% gas liquefaction and storage at low pressure. During peak electricity consumption periods, the liquid air is vaporized to release process gas, realizing a peak-shaving operation mode of storing liquid during off-peak hours and supplying gas during peak hours, thus improving the operational flexibility and economy of the process gas supply system.

[0023] 3. This invention, by setting up inclined-temperature cold storage tanks, constant-temperature cold storage tanks, and phase-change cold storage tanks, enables the tiered storage and release of low-temperature cold energy during the liquefaction and vaporization processes of air. This improves the efficiency of cold energy utilization and the matching degree of the heat exchange process, thereby enhancing heat transfer efficiency and significantly increasing the liquefaction rate. Compared with traditional process gas peak-shaving operation systems, this invention can greatly reduce the footprint of the entire system. Attached Figure Description

[0024] Figure 1 A schematic diagram of a large-capacity process gas peak-shaving operation system based on liquid air storage provided in an embodiment of the present invention;

[0025] Figure 2 This is a comparison chart showing the required tank volume between the system in this embodiment and the traditional system.

[0026] In the picture:

[0027] 100 Air liquefaction unit, 101 First compressor, 102 First cooler, 103 Second compressor, 104 Second cooler, 105 Adsorption tower, 106 Flow divider, 107 Third compressor, 108 Third cooler, 109 Water pump, 110 Heater, 111 Desorption tower; 200 Air vaporization unit, 201 Inclined temperature cold storage tank, 202 Constant temperature cold storage tank, 203 Phase change cold storage tank, 204 Liquid air tank, 205 Pressure reducing valve. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] This application provides a large-capacity process gas peak-shaving operation system and method based on liquid air storage. Its core technical concept lies in:

[0031] On the one hand, by storing liquid during off-peak hours and supplying gas during peak hours, the process gas can be shaving off to reduce system operating costs. On the other hand, by adjusting the operating pressure of the air liquefaction and vaporization units, 100% gas liquefaction can be achieved, reducing system size and investment costs.

[0032] On the other hand, by using inclined temperature cold storage tanks, constant temperature cold storage tanks and phase change cold storage tanks to achieve cascade storage and release of cold energy, heat transfer efficiency is improved and liquefaction rate is greatly increased. Compared with traditional process gas peak shaving operation systems, the footprint of the entire system can be greatly reduced.

[0033] By adjusting the operating pressure of each unit and the tiered storage and release of cold energy, this invention can effectively overcome the limitations of traditional gas peak-shaving operation systems and significantly reduce system size and investment costs.

[0034] The following describes the structural composition, workflow, and core control logic of the present invention in detail through multiple embodiments.

[0035] Example 1

[0036] This invention provides a large-capacity process gas peak-shaving operation system based on liquid air storage, such as... Figure 1 As shown, the system mainly consists of two core units: an air liquefaction unit 100 and an air vaporization unit 200. The air liquefaction unit 100 and the air vaporization unit 200 share a common inclined temperature cold storage tank 201, a constant temperature cold storage tank 202, and a phase change cold storage tank 203.

[0037] The structural connections are as follows: First, the air liquefaction unit 100 includes a first compressor 101, a first cooler 102, a second compressor 103, a second cooler 104, an adsorption tower 105, a distributor 106, a third compressor 107, a third cooler 108, a water pump 109, a heater 110, a desorption tower 111, an inclined temperature cold storage tank 201, a constant temperature cold storage tank 202, and a phase change cold storage tank 203.

[0038] The input terminal of the air liquefaction unit 100, i.e., the input terminal of the first compressor 101, is used to input ambient air. The output terminal of the first compressor 101 is connected to the first input terminal of the first cooler 102. The first output terminal of the first cooler 102 is connected to the input terminal of the second compressor 103. The output terminal of the second compressor 103 is connected to the first input terminal of the second cooler 104. The first output terminal of the second cooler 104 is connected to the input terminal of the adsorption tower 105. The output terminal of the adsorption tower 105 is connected to the input terminal of the distributor 106. The first output terminal of the distributor 106 is connected to the input terminal of the third compressor 107. The output terminal of the third compressor 107 is connected to the first input terminal of the third cooler 108. The first output terminal of the third cooler 108 is connected to the first input terminal of the inclined temperature cold storage tank 201. The first output terminal of the inclined temperature cold storage tank 201 is connected to the first input terminal of the constant temperature cold storage tank 202.

[0039] The first output terminal of the constant temperature cold storage tank 202 is connected to the first input terminal of the phase change cold storage tank 203, and the first output terminal of the phase change cold storage tank 203 is connected to the input terminal of the liquid air tank 204 as the output terminal of the air liquefaction unit 100.

[0040] The second output terminals of the first cooler 102, the second output terminal of the second cooler 104, and the second output terminal of the third cooler 108 are connected to the input terminal of the water pump 109. The output terminal of the water pump 109 is connected to the second input terminal of the heater 110. The second output terminal of the heater 110 is connected to the second input terminals of the first cooler 102, the second cooler 104, and the third cooler 108. The second output terminal of the distributor 106 is connected to the first input terminal of the heater 110. The first output terminal of the heater 110 is connected to the input terminal of the desorption tower 111.

[0041] The air vaporization unit 200 includes a liquid air tank 204, a pressure reducing valve 205, a phase change cold storage tank 203, a constant temperature cold storage tank 202, and an inclined temperature cold storage tank 201, with the specific connection relationships as follows:

[0042] The input end of the liquid air tank 204 is connected to the first output end of the phase change cold storage tank 203 as the input end of the air vaporization unit 200. The output end of the liquid air tank 204 is connected to the input end of the pressure reducing valve 205. The output end of the pressure reducing valve 205 is connected to the second input end of the phase change cold storage tank 203. The second output end of the phase change cold storage tank 203 is connected to the second input end of the constant temperature cold storage tank 202. The second output end of the constant temperature cold storage tank 202 is connected to the second input end of the inclined temperature cold storage tank 201.

[0043] Working principle: During periods of low electricity demand, the system starts the air liquefaction process. The input end of the air liquefaction unit 100 (i.e. the input end of the first compressor 101) is used to input ambient air. The air passes through the first compressor 101, the second cooler 102, the second compressor 103 and the second cooler 104 in sequence to cool down before entering the adsorption tower 105 to remove impurities. The pure air output from the adsorption tower 105 is split into two streams by the splitter 106: one stream of gas enters the heater 110 from the second output of the splitter 106 via the first input of the heater 110 for heating, and then enters the desorption tower 111 from the first output of the heater 110 via the input of the desorption tower 111 for desorption. The heat source of the heater 110 is the heat released from the first cooler 102, the second cooler 104, and the third cooler 108. The other stream of gas enters the third compressor 107 from the first output of the splitter 106 for further compression, then enters the third cooler 108 for cooling, and then enters the inclined temperature cold storage tank 201 for pre-cooling. After that, it enters the constant temperature cold storage tank 202 for further cooling, and finally enters the phase change cold storage tank 203 to undergo gas-liquid phase change. Liquid air is output from the first output of the phase change cold storage tank 203 and enters the liquid air tank 204 from the input of the liquid air tank 204 for storage.

[0044] During peak electricity consumption periods, the system initiates the air vaporization process. Liquid air is output from the output terminal of the liquid air tank 204, enters the pressure reducing valve 205 through the input terminal of the pressure reducing valve 205 for cooling and depressurization, and then enters the phase change cold storage tank 203 to recover high-grade cold energy and become gaseous air. After that, it enters the constant temperature cold storage tank 202 to further recover medium-grade cold energy, and then enters the inclined temperature cold storage tank 201 to recover low-grade cold energy. Finally, gaseous air is output from the second output terminal of the inclined temperature cold storage tank 201.

[0045] In this implementation, during off-peak hours, the system purifies and compresses ambient air to 16 bar, then cools it down to -172.5°C through a series of cooling tanks: a tilting temperature tank, a constant temperature tank, and a phase change tank. The air is then stored as liquid air in a liquid air tank. During peak hours, the liquid air is further depressurized and cooled to 6 bar (-174.58°C) via a pressure reducing valve, further increasing the cooling energy.

[0046] The main node parameters of the large-capacity process gas peak shaving operation system based on liquid air storage in this embodiment are shown in Table 1 at a certain point in the middle.

[0047] Table 1 shows the main node parameters of the system at a certain intermediate moment.

[0048]

[0049] The required tank volume of this system is compared with that of traditional systems, for example... Figure 2As shown, the volume of compressed air tank required for 8 hours of gas storage in the traditional system is 11,916.7 m³, while the volume of liquid air tank required for 8 hours of air liquefaction in this system is 264.5 m³. The tank volume required by the traditional system is about 45 times that required by this system.

[0050] In summary, this invention purifies ambient air during off-peak hours by compressing it, then progressively cools it through a series of stages: a slope-temperature cold storage tank, a constant-temperature cold storage tank, and a phase-change cold storage tank. The air is completely liquefied and stored at low pressure. During peak hours, the liquefied air is depressurized and cooled by a pressure-reducing valve, then progressively vaporized through the phase-change, constant-temperature, and slope-temperature cold storage tanks. The vaporized cold energy is then stored in stages and supplied to process gases, achieving peak-shaving operation and reducing system operating costs. Furthermore, by adjusting the operating pressure of the air liquefaction and vaporization units, 100% gas liquefaction is achieved, reducing system size and investment costs. This invention achieves tiered storage and release of cold energy through slope-temperature, constant-temperature, and phase-change cold storage tanks, improving heat transfer efficiency and significantly increasing the liquefaction rate. Compared to traditional process gas peak-shaving systems, this invention can greatly reduce the overall system footprint.

[0051] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

[0052] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A large-capacity process gas peak-shaving operation system based on liquid air storage, characterized in that, include: An air liquefaction unit (100) is used to purify and compress outside air, cool it down in three cold storage tanks, and then liquefy it before outputting it to an air vaporization unit (200). The air liquefaction unit (100) includes a multi-stage compressor, multiple coolers, a distributor (106), a water pump (109), a heater (110), an adsorption tower (105), and a desorption tower (111) arranged in series. An air vaporization unit (200) is used to vaporize the compressed and liquefied liquid air through three cold storage tanks in stages; wherein, the air vaporization unit (200) includes a liquid air tank (204), a pressure reducing valve (205), a phase change cold storage tank (203), a constant temperature cold storage tank (202), and an inclined temperature cold storage tank (201). The air liquefaction unit (100) and the air vaporization unit (200) share the inclined temperature cold storage tank (201), the constant temperature cold storage tank (202), and the phase change cold storage tank (203).

2. The large-capacity process gas peak-shaving operation system based on liquid air storage as described in claim 1, characterized in that, The multi-stage compressor includes a first compressor (101), a second compressor (103), and a third compressor (107); the multiple coolers include a first cooler (102), a second cooler (104), and a third cooler (108); the input end of the first compressor (101) is used to input ambient air, the output end of the first compressor (101) is connected to the first input end of the first cooler (102), the first output end of the first cooler (102) is connected to the input end of the second compressor (103), the output end of the second compressor (103) is connected to the first input end of the second cooler (104), the first output end of the second cooler (104) is connected to the input end of the adsorption tower (105), and the adsorption tower (107) is connected to the input end of the adsorption tower (108). 5) The output end is connected to the input end of the splitter (106), the first output end of the splitter (106) is connected to the input end of the third compressor (107); the output end of the third compressor (107) is connected to the first input end of the third cooler (108), the first output end of the third cooler (108) is connected to the first input end of the inclined temperature cold storage tank (201), the first output end of the inclined temperature cold storage tank (201) is connected to the first input end of the constant temperature cold storage tank (202), the first output end of the constant temperature cold storage tank (202) is connected to the first input end of the phase change cold storage tank (203), and the first output end of the phase change cold storage tank (203) is connected to the input end of the liquid air tank (204) as the output end of the air liquefaction unit (100); The second output of the first cooler (102), the second output of the second cooler (104), and the second output of the third cooler (108) are connected to the input of the water pump (109). The output of the water pump (109) is connected to the second input of the heater (110). The second output of the heater (110) is connected to the second input of the first cooler (102), the second input of the second cooler (104), and the second input of the third cooler (108). The second output of the distributor (106) is connected to the first input of the heater (110). The first output of the heater (110) is connected to the input of the desorption tower (111).

3. The large-capacity process gas peak-shaving operation system based on liquid air storage as described in claim 1, characterized in that, The input end of the liquid air tank (204) is connected to the first output end of the phase change cold storage tank (203) as the input end of the air vaporization unit (200). The output end of the liquid air tank (204) is connected to the input end of the pressure reducing valve (205). The output end of the pressure reducing valve (205) is connected to the second input end of the phase change cold storage tank (203). The second output end of the phase change cold storage tank (203) is connected to the second input end of the constant temperature cold storage tank (202). The second output end of the constant temperature cold storage tank (202) is connected to the second input end of the inclined temperature cold storage tank (201).

4. The large-capacity process gas peak-shaving operation system based on liquid air storage as described in claim 2, characterized in that, In the air liquefaction unit (100), the ambient air is pressurized by a multi-stage compressor connected in series and then cooled by multiple coolers. After that, it enters the inclined temperature cold storage tank (201), the constant temperature cold storage tank (202) and the phase change cold storage tank (203) in sequence to cool down step by step. All the air is liquefied and stored in a low-pressure state.

5. A large-capacity process gas peak-shaving operation system based on liquid air storage as described in claim 4, characterized in that, During the air liquefaction process, the heat of compression generated by air compression is used by the heater (110) to provide heat energy for heating the diverted gas, and the generated high-temperature gas is used in the desorption tower (111).

6. The large-capacity process gas peak-shaving operation system based on liquid air storage as described in claim 3, characterized in that, Liquid air in the air vaporization unit (200) is output through the liquid air tank (204), and is depressurized and cooled by the pressure reducing valve (205). After being vaporized in stages through the phase change cold storage tank (203), the constant temperature cold storage tank (202) and the inclined temperature cold storage tank (201), it is supplied to the process gas.

7. A method for large-capacity process gas peak shaving operation based on liquid air storage, wherein the method is implemented using a large-capacity process gas peak shaving operation system based on liquid air storage as described in any one of claims 1 to 6, characterized in that, The methods include air liquefaction methods and air vaporization methods: During off-peak electricity hours, the air liquefaction unit (100) operates: after the ambient air is compressed and purified, it enters the inclined temperature cold storage tank (201), the constant temperature cold storage tank (202) and the phase change cold storage tank (203) to cool down step by step, and all the air is liquefied and stored in a low-pressure state. During peak electricity consumption periods, the air vaporization unit (200) operates: liquid air is depressurized and cooled through the pressure reducing valve (205) to further increase the low-temperature cold energy. It is then vaporized step by step through the phase change cold storage tank (203), the constant temperature cold storage tank (202), and the inclined temperature cold storage tank (201), and the vaporized cold energy is stored in stages to supply process gas.

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