Air liquefaction system with flexible cooling capacity

Abstract

This utility model relates to the technical field of liquid air energy storage systems, and in particular to an air liquefaction system with flexibly adjustable cooling capacity. The system includes a liquefaction cold box, a throttling and pressure-reducing device, a cold storage device, a gas-liquid separator, a flow control valve, a liquid air storage tank, a refrigeration expansion device, and related pipelines. This air liquefaction system, by installing a flow control valve and pipelines between the liquid air storage tank and the liquefaction cold box, allows for flexible adjustment and control of the air liquefaction process based on the air liquefaction operation status and corresponding control strategies within the cold box. This, combined with the cold storage device, gas-liquid separator, and refrigeration expansion device, enables flexible adjustment and control of the cooling energy demand and process requirements during the air liquefaction process. This reduces potential risks such as instability and uncontrollability in the liquefaction process caused by uncontrollable factors such as engineering flaws, equipment performance deviations, or cooling capacity loss, thereby improving the controllability and flexibility of project operation.

Description

Technical Field

[0001] This utility model relates to the technical field of liquefied air energy storage systems, and in particular to an air liquefaction system with flexibly adjustable cooling capacity. Background Technology

[0002] Liquid air energy storage technology stores energy by cryogenically liquefying air into liquid air. When releasing this energy to generate electricity, the liquid air is pressurized, vaporized, and reheated before being fed into an expansion generator to produce electricity. The core process involves the cryogenic liquefaction of air through a liquefaction unit.

[0003] Because the air liquefaction process is highly complex, it is necessary to strictly control the pressure, temperature, and cooling balance of the system to ensure the stable operation of the liquefaction process.

[0004] In existing liquid air energy storage systems, the cold energy for air liquefaction primarily relies on the cold energy recovered and stored by the accumulator, the cold energy carried by the low-temperature reflux air during depressurization, or the combined cold energy generated by the circulation and refrigeration of some high-pressure air. Because the low-temperature reflux air flow rate and circulation refrigeration capacity are variable and unsteady-state processes during the initial system startup, it requires a certain period of operation to reach the design-required stable operating conditions. This unsteady-state process prolongs the liquefaction process, increasing energy consumption and the complexity of stable operation control. Furthermore, due to the unavoidable uncertainties in cold energy loss during operation and resting periods, the actual process parameters of the low-temperature heat exchange in the liquefaction stage will fluctuate from the design parameters. These uncertainties significantly impact the performance of the air liquefaction process and the entire energy storage system. Existing liquid air energy storage systems lack flexible adjustment and control measures for these situations during the liquefaction process. Utility Model Content

[0005] The purpose of this invention is to provide an air liquefaction system with flexibly adjustable cooling capacity to solve the problems existing in the liquefaction stage of the current liquefied air energy storage system mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: an air liquefaction system with flexibly adjustable cooling capacity, comprising a liquefaction cold box, a throttling and pressure-reducing device, a gas-liquid separation device, a liquid air storage tank, a cold storage device, a flow control valve, and a refrigeration expansion device;

[0007] The hot end inlet pipe of the liquefaction cold box is connected to the outlet of the compressor terminal cooler, and high-pressure room temperature or low temperature air to be liquefied flows in. The hot end outlet pipe of the liquefaction cold box is connected to the inlet of the throttling and pressure reducing device.

[0008] The first cold end inlet of the liquefied cold box is connected to the gaseous outlet end of the gas-liquid separation device, and the first cold end outlet pipeline of the liquefied cold box is converged to the inlet of the low-pressure compressor according to the pressure conditions.

[0009] The second cold end inlet pipe of the liquefied cold box is connected to the cold release loop outlet of the cold storage device;

[0010] The third cold end inlet pipe of the liquefied cold box is connected to the outlet end of the flow control valve;

[0011] The hot end outlet branch of the liquefied cold box is connected to the inlet of the refrigeration expansion device, which expands a portion of the high-pressure air to achieve refrigeration.

[0012] Preferably, the second cold end outlet pipe of the liquefied cold box is connected to the inlet of the cold release loop of the cold storage device to form a cold release circulation loop. The cold storage device recovers and stores the cold energy released by the evaporation of liquid air through the cold storage circulation loop formed by the cold storage end inlet pipe and the cold storage end outlet pipe, and provides the recovered and stored cold energy to the liquefied cold box for air liquefaction through the cold release circulation loop.

[0013] Preferably, the flow control valve is connected to the liquid air storage tank and can be flexibly adjusted according to the deviation of the air liquefaction cooling capacity demand of the liquefied cold box to provide an appropriate amount of liquid air for supplemental cooling or subcooling. The third cold end outlet pipeline of the liquefied cold box is connected to the inlet of the low-pressure compressor according to the pressure conditions.

[0014] Preferably, the inlet of the gas-liquid separation device is connected to the throttling and pressure-reducing device, and its gaseous outlet is connected to the first cold end inlet of the liquefied cold box, so as to deliver the unliquefied low-temperature air to the liquefied cold box to provide cold energy.

[0015] Preferably, the refrigeration outlet pipe of the refrigeration expansion device is connected to the first cold end inlet to provide cold energy for the air liquefaction of the liquefaction cold box.

[0016] Preferably, depending on the different process designs, the liquefaction process may include a refrigeration expansion device and inlet / outlet pipes, or it may not include a refrigeration expansion device and inlet / outlet pipes.

[0017] Preferably, the throttling and pressure-reducing device can be a throttling valve, a cryogenic / liquid expander, or a combination of both.

[0018] Compared with existing technologies, the beneficial effects of this utility model are as follows: This air liquefaction system with flexible adjustable cooling capacity, through the setting of a liquefaction cold box, hot end inlet pipe, hot end outlet pipe, throttling and pressure reducing device, gas-liquid separation device, liquid air storage tank, cold storage device, flow control valve, first cold end inlet / outlet pipe, second cold end inlet / outlet pipe, third cold end inlet / outlet pipe, and refrigeration expansion device and pipe, has great controllability in adjusting the demand for cold energy in the air liquefaction process. It can flexibly adjust the supply of liquefied cooling capacity according to the liquefaction operation of air in the liquefaction cold box, alleviate potential risks such as instability and uncontrollability of the liquefaction process caused by uncontrollable factors such as engineering, equipment performance deviation, or cooling capacity loss, improve the controllability and flexibility of project commissioning, reduce the risks and impacts caused by system operation fluctuations, improve system reliability, and reduce system operation and maintenance costs to a certain extent. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an air liquefaction system with adjustable cooling capacity according to the present invention;

[0020] Figure 2 This is a schematic diagram of another air liquefaction system according to the present invention;

[0021] In the diagram: 1. Liquefied air cooler; 2. Hot end inlet pipe; 3. Hot end outlet pipe; 4. Throttling and pressure reducing device; 5. Throttling and pressure reducing pipe; 6. Gas-liquid separator; 7. Liquid-air pipe; 8. First cold end inlet; 9. First cold end outlet pipe; 10. Liquid air storage tank; 11. Liquid-air outlet pipe; 12. Cold storage device; 13. Second cold end inlet pipe; 14. Second cold end outlet pipe; 15. Cold storage end inlet pipe; 16. Cold storage end outlet pipe; 17. Flow control valve; 18. Third cold end inlet pipe; 19. Third cold end outlet pipe; 20. Refrigeration expansion device; 21. Hot end outlet branch pipe; 22. Refrigeration outlet pipe. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Please see Figure 1-2 This utility model provides a technical solution: an air liquefaction system with adjustable cooling capacity, including a liquefaction cold box 1, a throttling and pressure reducing device 4, a gas-liquid separation device 6, a liquid air storage tank 10, a cold storage device 12, a flow control valve 17, a refrigeration expansion device 20, and related pipelines.

[0024] The hot end inlet pipe 2 of the liquefaction cold box 1 is connected to the outlet of the compressor terminal cooler, and high-pressure normal temperature or low temperature air to be liquefied flows in. The hot end outlet pipe 3 of the liquefaction cold box 1 is connected to the inlet of the throttling and pressure reducing device 4.

[0025] The first cold end inlet 8 of the liquefied cold box 1 is connected to the gaseous outlet end of the gas-liquid separation device 6. The first cold end outlet pipeline 9 can be connected to the low-pressure compressor inlet at low pressure or discharged into the atmosphere at normal pressure, depending on the process design.

[0026] The second cold end inlet pipe 13 of the liquefied cold box 1 is connected to the cold release loop outlet of the cold storage device 12, and the second cold end outlet pipe 14 of the liquefied cold box 1 is connected to the cold release loop inlet of the cold storage device 12, forming a cold release circulation loop; the cold storage device 12 recovers and stores the cold energy released by the evaporation of liquid air through the cold storage circulation loop formed by the cold storage end inlet pipe 15 and the cold storage end outlet pipe 16, and provides the recovered and stored cold energy to the liquefied cold box 1 for air liquefaction through the cold release circulation loop;

[0027] The third cold end inlet pipe 18 of the liquefied cold box 1 is connected to the outlet end of the flow control valve 17. The flow control valve 17 is connected to the liquid air storage tank 10. It can be flexibly adjusted according to the deviation of the air liquefaction cooling demand of the liquefied cold box 1 during system operation to provide an appropriate amount of liquid air for supplemental cooling or subcooling, so as to restore the stable operating condition of liquefaction cooling supply and demand balance. The third cold end outlet pipe 19 can be low pressure collected to the low pressure compressor inlet or atmospheric pressure discharged into the atmosphere, depending on the process design.

[0028] The flow control valve 17 can be controlled manually, automatically via a remote control system, or a combination of both.

[0029] The inlet of the gas-liquid separator 6 is connected to the throttling and pressure-reducing device 4, and its gaseous outlet is connected to the first cold end inlet 8 of the liquefied cold box 1, which delivers the unliquefied low-temperature air to the liquefied cold box 1 to provide cold energy. The gas-liquid separator 6 delivers the liquid air to the liquid air storage tank 10 for storage through the liquid air pipeline 7.

[0030] Furthermore, in another specific embodiment, a refrigeration expansion device 20 and corresponding pipelines can be added. The inlet of the refrigeration expansion device 20 is connected to the hot end outlet branch pipeline 21 of the liquefied cold box 1. Refrigeration is achieved by expanding part of the high-pressure air. The refrigeration outlet pipeline 22 of the refrigeration expansion device 20 is connected to the first cold end inlet 8 to provide cold energy for the liquefaction of air in the liquefied cold box 1.

[0031] Working principle: High-pressure ambient or low-temperature air at the hot end inlet of the liquefied air cooling box 1 exchanges heat with the cold energy provided by the first, second, and third cold end pipelines inside the liquefied air cooling box 1, releasing heat and cooling down to a low temperature or even a liquefied state. After being depressurized by the throttling and depressurization device 4 and separated by gas and liquid, the liquid air is stored in the liquid air storage tank 10. The liquefied air cooling box 1 is connected to the gas outlet end of the gas-liquid separation device 6, forming the first cold end pipeline of the liquefied air cooling box 1, which backflows the depressurized low-temperature gaseous air to the cold box. The cooling energy is used for air cooling and liquefaction. The first cold-end outlet pipe 9 can discharge air or return pressurized air to the low-pressure side compressor unit inlet, depending on the process and requirements. The liquefaction cold box 1 is connected to the cold storage device 12's cold release circulation pipe, forming the second cold-end pipe 10 of the liquefaction cold box 1. The cold storage device 12 releases cold energy through the second cold-end inlet and outlet pipes, providing the stored cold energy to the liquefaction cold box 1. Through heat exchange, the liquefaction cold box 1 absorbs the cold energy from the cold storage device 12 for air cooling and liquefaction. 1. The refrigeration expansion device 20 is connected to the refrigeration expansion device 20 through the hot end outlet branch pipe 21 and the refrigeration outlet pipe 22 to form a circulating refrigeration loop. The refrigeration expansion device 20 provides the circulating cold energy generated by the circulation to the liquefied cold box 1 through the first cold end pipe via the refrigeration outlet pipe 22, providing circulating cold energy to the liquefied cold box 1. The liquefied cold box 1 is connected to the flow control valve 17 connected to the liquid air storage tank to form the third cold end pipe of the liquefied cold box 1. The opening degree of the flow control valve 17 can control the appropriate amount of liquid air to be depressurized and throttled and delivered to the liquefied cold box 1 to provide appropriate supplemental cooling or subcooling. This reduces the risks and problems caused by large deviations in the cooling capacity of the liquefied cold box 1 and unstable and uncontrollable liquefaction process due to uncontrollable factors such as engineering, equipment process errors, and system cooling losses during system operation. This helps to achieve a stable design condition of supply and demand balance of liquefied cooling capacity, improve the controllability and flexibility of project commissioning. The flow control valve 17 can be controlled manually or automatically through a remote control system, or a combination of both methods.

[0032] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An air liquefaction system with flexibly adjustable cooling capacity, characterized in that, It includes a liquefied cold box (1), a throttling and pressure reducing device (4), a gas-liquid separation device (6), a liquid air storage tank (10), a cold storage device (12), a flow control valve (17), and a refrigeration expansion device (20). The hot end inlet pipe (2) of the liquefaction cold box (1) is connected to the outlet of the compressor terminal cooler, and high-pressure normal temperature or low temperature air to be liquefied flows in. The hot end outlet pipe (3) of the liquefaction cold box (1) is connected to the inlet of the throttling and pressure reducing device (4). The first cold end inlet (8) of the liquefied cold box (1) is connected to the gaseous outlet end of the gas-liquid separation device (6), and the first cold end outlet pipeline (9) of the liquefied cold box (1) is gathered to the inlet of the low-pressure compressor according to the pressure conditions. The second cold end inlet pipe (13) of the liquefied cold box (1) is connected to the cold release loop outlet of the cold storage device (12); The third cold end inlet pipe (18) of the liquefied cold box (1) is connected to the outlet end of the flow control valve (17); The hot end outlet branch pipe (21) of the liquefied cold box (1) is connected to the inlet of the refrigeration expansion device (20) to expand part of the high-pressure air to achieve refrigeration.

2. The air liquefaction system with flexibly adjustable cooling capacity according to claim 1, characterized in that, The second cold end outlet pipe (14) of the liquefied cold box (1) is connected to the cold release loop inlet of the cold storage device (12) to form a cold release loop. The cold storage device (12) recovers and stores the cold energy released by the evaporation of liquid air through the cold storage loop formed by the cold storage end inlet pipe (15) and the cold storage end outlet pipe (16). The recovered and stored cold energy is provided to the liquefied cold box (1) for air liquefaction through the cold release loop.

3. The air liquefaction system with flexibly adjustable cooling capacity according to claim 1, characterized in that, The flow control valve (17) is connected to the liquid air storage tank (10), and can be flexibly adjusted according to the deviation of the air liquefaction cooling capacity demand of the liquefied cold box (1) to provide an appropriate amount of liquid air for supplemental cooling or subcooling. The third cold end outlet pipe (19) of the liquefied cold box (1) is connected to the inlet of the low-pressure compressor according to the pressure conditions.

4. The air liquefaction system with flexibly adjustable cooling capacity according to claim 1, characterized in that, The inlet of the gas-liquid separation device (6) is connected to the throttling and pressure-reducing device (4), and its gaseous outlet is connected to the first cold end inlet (8) of the liquefied cold box (1) to deliver unliquefied low-temperature air to the liquefied cold box (1) to provide cold energy.

5. The air liquefaction system with flexibly adjustable cooling capacity according to claim 1, characterized in that, The refrigeration outlet pipe (22) of the refrigeration expansion device (20) is connected to the first cold end inlet (8) to provide cold energy for the air liquefaction of the liquefaction cold box (1).

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