Air separation pre-cooling system and air cooling method

Abstract

The invention discloses an air separation pre-cooling system and an air cooling method. The air separation pre-cooling system comprises a tower body, a compressed air assembly, a water circulation assembly and a waste nitrogen assembly. A liquid storage part for storing circulating water is arranged at the bottom of the tower body; the compressed air assembly comprises a cooling coil, and the cooling coil is fixedly mounted in the tower body and used for introducing high-temperature and high-pressure air; the water circulation assembly comprises a water inlet pipe, a water outlet pipe and a driving pump, one end of the water outlet pipe is communicated with the top of the tower body, the other end of the water outlet pipe is connected with an outlet of the driving pump, and one end of the water inlet pipe is connected with an inlet of the driving pump; the waste nitrogen assembly comprises a nitrogen inlet pipe, the nitrogen inlet pipe is connected with the tower body and is used for introducing dry waste nitrogen into the tower body, circulating water sprayed from the upper part of the tower top is used for cooling air in the cooling coil, and the dry waste nitrogen is used for evaporating and cooling the circulating water. The device can prevent air entrained with liquid water from entering the purification system, improves the working efficiency of the pre-cooling and purification system, saves energy consumption, and reduces the occupied area.

Description

Technical Field

[0001] This invention relates to the field of cryogenic air separation technology, and in particular to an air separation precooling system and air cooling method. Background Technology

[0002] The precooling system for cryogenic air separation processes uses air-cooled towers and water-cooled towers as core equipment. In traditional precooling systems, compressed, high-temperature, high-pressure air is introduced from the bottom of the air-cooled tower, flows upward through the packing layer inside the tower, and forms a direct contact counter-current heat exchange with the low-temperature cooling water supplied by the water-cooled tower. The heat of the air is absorbed by the low-temperature water, and the air is discharged from the top of the air-cooled tower and enters the downstream process. However, this design has significant technical drawbacks: when the air velocity inside the air-cooled tower is high or the demister is improperly designed / failed, liquid water can be entrained by the air and carried to the downstream molecular sieve purification system, affecting the efficiency of the purification system. Moreover, the existing separate arrangement of the air-cooled tower and water-cooled tower not only increases the equipment footprint and infrastructure investment, but also increases the difficulty of system operation and maintenance and the cost of downtime maintenance due to complex piping connections and dispersed maintenance spaces. Summary of the Invention

[0003] The purpose of this invention is to provide an air separation precooling system and air cooling method to solve the problems existing in the prior art, prevent air from carrying liquid water into the purification system, improve the working efficiency of the precooling and purification system, save energy, and reduce the floor space.

[0004] To achieve the above objectives, the present invention provides the following solution: This invention provides an air separation precooling system, comprising a tower body, a compressed air assembly, a water circulation assembly, and a waste nitrogen assembly. The tower body has a liquid storage section at its bottom for storing circulating water. The compressed air assembly includes a cooling coil, which is fixedly installed within the tower body and is used to introduce high-temperature, high-pressure air. The water circulation assembly includes an inlet pipe, an outlet pipe, and a drive pump. One end of the outlet pipe is connected to the top of the tower body, and the other end is connected to the outlet of the drive pump. The inlet of the drive pump is connected to one end of the inlet pipe, and the other end is connected to the liquid storage section. The waste nitrogen assembly includes a nitrogen inlet pipe connected to the tower body for introducing dry waste nitrogen into the tower body. Circulating water sprayed from the top of the tower is used to cool the air in the cooling coil, and the dry waste nitrogen is used to evaporate and cool the circulating water.

[0005] Preferably, it also includes packing material, which is fixedly disposed in the tower body and located above the liquid storage section.

[0006] Preferably, the waste nitrogen gas assembly further includes a gas distribution pipe, which is installed inside the tower body and located between the packing and the liquid storage section, with the gas holes of the gas distribution pipe facing the liquid storage section.

[0007] Preferably, the compressed air assembly further includes an air inlet pipe and an air outlet pipe, the air inlet pipe being connected to the inlet of the cooling coil, the air outlet pipe being connected to the outlet of the cooling coil, and the air inlet pipe being located above the air outlet pipe.

[0008] Preferably, it also includes a liquid level monitoring device, which is connected to the liquid storage unit and is used to monitor the liquid level of the circulating water in the liquid storage unit.

[0009] Preferably, it also includes a water quality testing device, which is connected to the liquid storage unit and is used to test the water quality of the circulating water in the liquid storage unit.

[0010] Preferably, the tower body further includes a water supply pipe, a sewage discharge pipe, and an overflow pipe. One end of the water supply pipe is connected to a water storage tank, and the other end of the water supply pipe is connected to the liquid storage section. A valve is installed on the water supply pipe. The sewage discharge pipe is connected to the lowest point of the tower body for discharging sewage from the liquid storage section. The overflow pipe is connected to the tower body, and the overflow port of the overflow pipe is higher than the water supply port of the water supply pipe.

[0011] Preferably, the water circulation assembly further includes a water distributor, which is installed inside the tower and connected to the outlet pipe.

[0012] Preferably, it also includes a demister, which is installed inside the tower body and located above the water distributor.

[0013] The present invention also provides an air-cooling method according to the air separation precooling system, comprising the following steps: Step 1: Inject circulating water to the preset liquid level into the liquid storage section of the tower, and then start the drive pump. The circulating water is transported to the top of the tower through the inlet pipe, drive pump and outlet pipe, and then sprayed out through the spray device. Step 2: Dry nitrogen gas is introduced into the tower through the nitrogen inlet pipe, forming a counter-current flow contact with the circulating water that is sprayed down. Water molecules evaporate and absorb heat in the dry nitrogen gas, thereby cooling the circulating water. Step 3: High-temperature and high-pressure air is introduced into the cooling coil inside the tower. It undergoes indirect heat exchange with the cooled circulating water inside the tower through the wall of the cooling coil. After cooling, the air is transported to the subsequent processing unit through the air outlet pipe.

[0014] The present invention achieves the following technical effects compared to the prior art: This invention provides an air separation precooling system and air cooling method, integrating the functions of a water-cooling tower and an air-cooling tower, which are separate in a conventional air-water cooling system, into a single tower body. The circulating water is cooled by counter-current flow of circulating water and dried nitrogen gas, and the air is cooled by indirect contact between the cooling coil and the low-temperature circulating water. A single tower achieves the cooling effect of a traditional dual-tower system, overcoming the design limitations of traditional systems that are geographically dispersed and require a large footprint. High-temperature, high-pressure air flows within a closed cooling coil, completely isolated from the circulating water and dried nitrogen gas, avoiding direct contact between the gas and water that could lead to increased humidity. The cooled air has stable moisture content and purity, preventing liquid water from being carried downstream to the molecular sieve purification system, thus improving the efficiency of the purification system and enhancing the overall operational reliability of the air separation unit. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the air separation precooling system.

[0017] In the diagram: 1-Tower body; 2-Cooling coil; 3-Air inlet pipe; 4-Air outlet pipe; 5-Water inlet pipe; 6-Water outlet pipe; 7-Drive pump; 8-Water distributor; 9-Nitrogen inlet pipe; 10-Air distribution pipe; 11-Packing; 12-Demister; 13-Liquid level monitoring device; 14-Water quality testing device; 15-Water replenishment pipe; 16-Sewage pipe; 17-Overflow pipe; 18-Roof. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The purpose of this invention is to provide an air separation precooling system and air cooling method to solve the problems existing in the prior art, prevent air from carrying liquid water into the purification system, improve the working efficiency of the precooling and purification system, save energy, and reduce the floor space.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 This embodiment provides an air separation precooling system, such as Figure 1 As shown, the system includes a tower body 1, a compressed air assembly, a water circulation assembly, and a waste nitrogen assembly. The bottom of the tower body 1 has a liquid storage section for storing circulating water. The compressed air assembly includes a cooling coil 2, which is fixedly installed inside the tower body 1 and is used to introduce high-temperature and high-pressure air. The water circulation assembly includes an inlet pipe 5, an outlet pipe 6, and a drive pump 7. One end of the outlet pipe 6 is connected to the top of the tower body 1, and the other end of the outlet pipe 6 is connected to the outlet of the drive pump 7. The inlet of the drive pump 7 is connected to one end of the inlet pipe 5, and the other end of the inlet pipe 5 is connected to the liquid storage section. The waste nitrogen assembly includes a nitrogen inlet pipe 9, which is connected to the tower body 1 and is used to introduce dry waste nitrogen into the tower body 1. Circulating water sprayed from the top of the tower is used to cool the air in the cooling coil 2, and the dry waste nitrogen is used to evaporate and cool the circulating water. By integrating the functions of the separate water-cooling tower and air-cooling tower in a traditional air-water cooling system, the system achieves evaporative cooling through counter-current flow of circulating water and dried nitrogen. The cooled circulating water then indirectly cools the air via cooling coil 2. A single tower achieves the cooling effect of a traditional dual-tower system, effectively overcoming the limitations of traditional systems with their dispersed layout and large footprint. High-temperature, high-pressure air flows within the enclosed cooling coil 2, completely isolated from the circulating water and dried nitrogen. This prevents the air from directly contacting water, thus avoiding humidity increases and ensuring stable moisture content and purity of the cooled air. It also prevents liquid water from being carried into the downstream molecular sieve purification system, thereby guaranteeing purification system efficiency and improving the overall operational reliability of the air separation unit. Simultaneously, the system directly utilizes the dried nitrogen produced by the air separation unit as the cooling medium, eliminating the need for an external gas source. This achieves waste resource utilization, improves energy and material utilization, and helps further reduce system energy consumption.

[0022] In a further preferred embodiment of this invention, the air separation precooling system further includes a packing 11. The packing 11 is fixedly installed inside the tower body 1 and is located above the liquid storage section. When the circulating water after heat exchange with the air flows down through the packing 11, the porous structure and high specific surface area of ​​the packing 11 can disperse the water flow into a fine liquid film or droplets, significantly increasing the contact area between the water and the dried nitrogen gas, and prolonging the gas-liquid contact time, thereby promoting efficient heat transfer and achieving deep cooling of the circulating water.

[0023] In a further preferred embodiment of this invention, the waste nitrogen gas assembly further includes a gas distribution pipe 10. The gas distribution pipe 10 is installed inside the tower body 1, located between the packing 11 and the liquid storage section, with the vents of the gas distribution pipe 10 facing the liquid storage section. After being dispersed by the uniform gas distribution structure of the gas distribution pipe 10, the dried waste nitrogen gas can form a uniform gas curtain that penetrates upwards through the packing 11 layer, achieving omnidirectional countercurrent contact with the circulating water flowing downwards through the packing 11, ensuring the uniformity and sufficiency of gas-liquid heat exchange. The downward-facing vents of the gas distribution pipe 10 prevent spray water from entering, avoiding moisture from entering the gas distribution pipe 10 and causing problems such as vent blockage and obstructed airflow, thus ensuring gas distribution stability.

[0024] In a further preferred embodiment of this invention, the compressed air assembly further includes an air inlet pipe 3 and an air outlet pipe 4. The air inlet pipe 3 is connected to the inlet of the cooling coil 2, and the air outlet pipe 4 is connected to the outlet of the cooling coil 2. The air inlet pipe 3 is located above the air outlet pipe 4. The air inlet pipe 3 is installed at a higher height than the air outlet pipe 4, forming a compressed air flow path that is inlet at the top and outlet at the bottom. This ensures that the compressed air flows fully through the tube bundle within the cooling coil 2, guaranteeing the heat exchange efficiency with the low-temperature circulating water outside the tubes.

[0025] In a further preferred embodiment of this invention, the air separation precooling system also includes a liquid level monitoring device 13, which is connected to the liquid storage section and is used to monitor the liquid level of the circulating water in the liquid storage section. Stable liquid level control provides a basic guarantee for the uniform spraying of circulating water and the efficient heat exchange of the packing layer 11. When the liquid level in the liquid storage section is too high, the circulating water submerges the gas distribution pipe 10 located above the liquid storage section, resulting in uneven distribution of polluted nitrogen gas, thereby ensuring the gas-liquid heat exchange efficiency. When the liquid level is lower than a preset threshold, it prevents the drive pump 7 from cavitation and dry running failures caused by air intake, and extends the service life of the pump.

[0026] In a further preferred embodiment of this invention, the air separation precooling system also includes a water quality detection device 14. The water quality detection device 14 is installed in the liquid storage section and is used to detect the water quality of the circulating water in the liquid storage section. When the detection result shows that the water quality exceeds the standard, sewage can be discharged through the sewage pipe 16, or a chemical agent can be added to the circulating water for maintenance, so as to ensure the stability of the heat exchange performance of the circulating water and extend the overall service life of the precooling system.

[0027] In a further preferred embodiment of this invention, the tower body 1 further includes a water supply pipe 15, a sewage discharge pipe 16, and an overflow pipe 17. One end of the water supply pipe 15 is connected to a water storage tank, and the other end of the water supply pipe 15 is connected to a liquid storage section. A valve is installed on the water supply pipe 15. The sewage discharge pipe 16 is connected to the lowest point of the tower body 1 and is used to discharge sewage from the liquid storage section. The overflow pipe 17 is connected to the tower body 1, and the overflow port of the overflow pipe 17 is higher than the water supply port of the water supply pipe 15. When the liquid level monitoring device 13 detects that the circulating water level in the storage compartment is lower than the preset threshold, it automatically opens the water supply pipe 15 valve to replenish the storage compartment with fresh water, maintaining a stable total circulating water volume and ensuring the water supply to the pump and the heat exchange requirements of the packing layer 11. When the water quality monitoring device 14 detects that the circulating water quality exceeds the standard, it opens the drain valve to discharge the deteriorated water in the storage compartment, and cooperates with subsequent water replenishment to achieve water quality renewal, avoiding equipment corrosion or pipeline blockage caused by impurity deposition. When the liquid level monitoring device 13 malfunctions or the water supply pipe 15 valve is abnormal, causing the liquid level in the storage compartment to rise continuously, the circulating water is automatically discharged through the overflow pipe 17, forming a dual liquid level protection to prevent high liquid level water from flooding the air distribution pipe 10 and avoiding risks such as uneven air distribution and equipment damage.

[0028] In a further preferred embodiment of this invention, the water circulation assembly further includes a water distributor 8, which is installed inside the tower body 1 and connected to the outlet pipe 6. The water distributor 8 can evenly spray low-temperature circulating water from the top of the tower body 1 to the lower packing layer 11, ensuring the cooling efficiency of the circulating water and the heat exchange stability of the cooling coil 2.

[0029] In a further preferred embodiment of this invention, the air separation precooling system also includes a demister 12, which is installed inside the tower body 1 and located above the water distributor 8. The demister 12 can significantly reduce the evaporation loss of circulating water, thereby achieving the effect of water saving and consumption reduction.

[0030] In a further preferred embodiment of this invention, the exhaust port at the top of the tower is provided with a canopy 18 to prevent rainwater or dust and other impurities from falling into the tower body 1 and affecting the water quality, thus affecting the performance and lifespan of the air separation precooling system.

[0031] Example 2 This embodiment provides an air cooling method for an air separation precooling system according to Embodiment 1, comprising the following steps: Step 1: Inject circulating water at a preset level into the liquid storage section of tower body 1, and then start the drive pump 7. The circulating water is transported to the top of tower body 1 through the inlet pipe 5, drive pump 7 and outlet pipe 6, and then sprayed out through the spraying device. Step 2: Dry nitrogen gas is introduced into the tower body 1 through nitrogen inlet pipe 9, and forms a counter-current flow contact with the circulating water that is sprayed down. Water molecules evaporate and absorb heat in the dry nitrogen gas, thereby cooling the circulating water. Step 3: High-temperature and high-pressure air is introduced into the cooling coil 2 inside the tower body 1. The air undergoes indirect heat exchange with the cooled circulating water inside the tower body 1 through the wall of the cooling coil 2. After cooling, the air is transported to the subsequent processing unit through the air outlet pipe.

[0032] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An air separation precooling system, characterized in that: The system includes a tower body, a compressed air assembly, a water circulation assembly, and a waste nitrogen assembly. The tower body has a storage compartment at its bottom for storing circulating water. The compressed air assembly includes a cooling coil, which is fixedly installed inside the tower body and is used to introduce high-temperature, high-pressure air. The water circulation assembly includes an inlet pipe, an outlet pipe, and a drive pump. One end of the outlet pipe is connected to the top of the tower body, and the other end is connected to the outlet of the drive pump. The inlet of the drive pump is connected to one end of the inlet pipe, and the other end is connected to the storage compartment. The waste nitrogen assembly includes a nitrogen inlet pipe connected to the tower body for introducing dry waste nitrogen into the tower body. Circulating water sprayed from the top of the tower is used to cool the air in the cooling coil, and the dry waste nitrogen is used to evaporate and cool the circulating water.

2. The air separation precooling system according to claim 1, characterized in that: It also includes packing material, which is fixedly disposed inside the tower body and located above the liquid storage section.

3. The air separation precooling system according to claim 2, characterized in that: The waste nitrogen gas assembly also includes a gas distribution pipe, which is installed inside the tower body and located between the packing and the liquid storage section, with the gas holes of the gas distribution pipe facing the liquid storage section.

4. The air separation precooling system according to claim 1, characterized in that: The compressed air assembly further includes an air inlet pipe and an air outlet pipe. The air inlet pipe is connected to the inlet of the cooling coil, and the air outlet pipe is connected to the outlet of the cooling coil. The air inlet pipe is located above the air outlet pipe.

5. The air separation precooling system according to claim 1, characterized in that: It also includes a liquid level monitoring device, which is connected to the liquid storage unit and is used to monitor the liquid level of the circulating water in the liquid storage unit.

6. The air separation precooling system according to claim 1, characterized in that: It also includes a water quality testing device, which is connected to the liquid storage unit and is used to test the water quality of the circulating water in the liquid storage unit.

7. The air separation precooling system according to claim 6, characterized in that: The tower body also includes a water supply pipe, a sewage discharge pipe, and an overflow pipe. One end of the water supply pipe is connected to the water storage tank, and the other end of the water supply pipe is connected to the liquid storage section. A valve is installed on the water supply pipe. The sewage discharge pipe is connected to the lowest point of the tower body and is used to discharge the sewage from the liquid storage section. The overflow pipe is connected to the tower body, and the overflow port of the overflow pipe is higher than the water supply port of the water supply pipe.

8. The air separation precooling system according to claim 1, characterized in that: The water circulation assembly also includes a water distributor, which is installed inside the tower and connected to the outlet pipe.

9. The air separation precooling system according to claim 8, characterized in that: It also includes a demister, which is installed inside the tower and located above the water distributor.

10. An air-cooling method for an air separation precooling system according to any one of claims 1-9, characterized in that: Includes the following steps: Step 1: Inject circulating water to the preset liquid level into the liquid storage section of the tower, and then start the drive pump. The circulating water is transported to the top of the tower through the inlet pipe, drive pump and outlet pipe, and then sprayed out through the spray device. Step 2: Dry nitrogen gas is introduced into the tower through the nitrogen inlet pipe, forming a counter-current flow contact with the circulating water that is sprayed down. Water molecules evaporate and absorb heat in the dry nitrogen gas, thereby cooling the circulating water. Step 3: High-temperature and high-pressure air is introduced into the cooling coil inside the tower. It undergoes indirect heat exchange with the cooled circulating water inside the tower through the wall of the cooling coil. After cooling, the air is transported to the subsequent processing unit through the air outlet pipe.

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