Air separation pre-cooling heat exchange system

Abstract

The invention relates to the technical field of deep cooling air separation processes, and discloses an air separation pre-cooling heat exchange system. Comprising a self-cleaning filter, an air compressor, an air compressor outlet air-to-air cooling tower main pipeline, an air compressor outlet air-to-heat exchanger bypass pipeline, a plate heat exchanger, a waste nitrogen main pipeline, a molecular sieve cold blowing pipeline, a waste nitrogen bypass branch, a regenerated gas generation pipeline, a cooling pipeline, a second temperature and pressure detection mechanism, a first regulating valve and an air cooling tower, waste nitrogen enters an electric heater front regulating valve, an electric heater, a molecular sieve purifier and a cooling water pump; the device has the advantages that heat of high-temperature air at the outlet of the air compressor is effectively utilized, and cold energy of waste nitrogen at the outlet of the molecular sieve is effectively utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic air separation processes, and particularly to an air separation pre-cooling and heat exchange system. Background Art

[0002] The cryogenic air separation process is used for the production of nitrogen, oxygen, and argon in medium to large-scale factories. For large domestic factories such as metallurgy and petrochemical industries, it is the preferred technology for obtaining high-purity industrial oxygen and nitrogen. The main equipment components of cryogenic air separation are: self-cleaning filters, air compressors, pre-cooling systems, molecular sieve purification systems, boosters, expanders, fractionation tower systems, nitrogen compression systems, spherical tanks, liquid storage tanks, and backup systems, etc.

[0003] The main process flow of its pre-cooling and purification system is as follows: The raw air is pressurized by the air compressor and sent to the lower part of the air cooling tower at a temperature of about 90°C. In the air cooling tower, the high-temperature hot air flows from bottom to top, and the normal-temperature water and low-temperature water flow from top to bottom. The hot air and water make countercurrent direct contact for heat and mass exchange. After being cooled by the air cooling tower, the air enters the molecular sieve purification system to adsorb harmful substances such as water, carbon dioxide, and acetylene, and then enters the subsequent process.

[0004] At the same time, after the molecular sieve adsorption is completed, it needs to be heated and desorbed for regeneration. Generally, a steam heater or an electric heater is used to heat the waste nitrogen. After heating to about 170°C, the hot waste nitrogen passes through the molecular sieve bed layer from top to bottom to desorb and regenerate the molecular sieve.

[0005] The defect of the prior art is that the high-temperature air at the outlet of the air compressor directly goes to the air cooling tower for cooling, and this part of the heat is not utilized. At the same time, the waste nitrogen of the molecular sieve is directly heated by the heater, and the cold energy of this part of the waste nitrogen is not effectively utilized.

[0006] Therefore, an air separation pre-cooling and heat exchange system is provided to solve the above problems. Summary of the Invention

[0007] The main purpose of the present invention is to solve the problem in the prior art that the high-temperature air at the outlet of the air compressor directly goes to the air cooling tower for cooling, and this part of the heat is not utilized. At the same time, the waste nitrogen of the molecular sieve is directly heated by the heater, and the cold energy of this part of the waste nitrogen is not effectively utilized.

[0008] The present invention provides an air separation pre-cooling and heat exchange system, and the air separation pre-cooling and heat exchange system includes:

[0009] Self-cleaning filter, air compressor, main pipeline for air at the outlet of the air compressor to the air cooling tower, bypass pipeline for air at the outlet of the air compressor to the heat exchanger, plate heat exchanger, main waste nitrogen pipeline, molecular sieve cold blow pipeline, waste nitrogen bypass branch, regeneration gas generation pipeline, cooling pipeline, second temperature and pressure detection mechanism, first regulating valve, air cooling tower, regulating valve before the waste nitrogen enters the electric heater, electric heater, molecular sieve purifier, and cooling water pump;

[0010] The self-cleaning filter is connected to the air compressor, and the air compressor is simultaneously connected to the main pipeline for the air from the air compressor outlet to the air cooling tower and the bypass pipeline for the air from the air compressor outlet to the heat exchanger; the main pipeline for the air from the air compressor outlet to the air cooling tower is connected to the air cooling tower; the bypass pipeline for the air from the air compressor outlet to the heat exchanger is connected to the plate heat exchanger, and the first port of the plate heat exchanger, the second temperature and pressure detection mechanism, the first regulating valve and the air cooling tower are connected in sequence; the second port of the plate heat exchanger is connected to the regeneration gas generation pipeline, and the third port of the plate heat exchanger is connected to the nitrogen purge bypass branch;

[0011] The air cooling tower is connected to the cooling pipeline, and the air cooling tower is also connected to the molecular sieve purifier through a cooling water pump;

[0012] The regeneration gas generation pipeline is connected to the electric heater, and the electric heater is connected to the molecular sieve purifier;

[0013] The nitrogen purge bypass branch is simultaneously connected to the main nitrogen pipeline and the molecular sieve cold blow pipeline, and the molecular sieve cold blow pipeline is connected to the molecular sieve purifier;

[0014] The front end of the molecular sieve cold blow pipeline is connected to the electric heater through a regulating valve before the nitrogen enters the electric heater.

[0015] Further, the main pipeline for the air from the air compressor outlet to the air cooling tower includes a regulating valve for the high-temperature air main pipeline. One end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the air compressor and the bypass pipeline for the air from the air compressor outlet to the heat exchanger, and the other end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the first regulating valve and the air cooling tower.

[0016] Further, the bypass pipeline for the air from the air compressor outlet to the heat exchanger includes: a regulating valve for the high-temperature air bypass pipeline, a buffer tank, a pressure gauge and a first bimetallic thermometer. The regulating valve for the high-temperature air bypass pipeline, the buffer tank, the pressure gauge and the first bimetallic thermometer are connected in sequence. The front end of the regulating valve for the high-temperature air bypass pipeline is simultaneously connected to the air compressor and the regulating valve for the high-temperature air main pipeline, and the first bimetallic thermometer is connected to the plate heat exchanger.

[0017] Further, the nitrogen purge bypass branch includes: a nitrogen inlet regulating valve and a second bimetallic thermometer. One end of the nitrogen inlet regulating valve is connected to the plate heat exchanger, the other end of the nitrogen inlet regulating valve is connected to the second bimetallic thermometer, and the second bimetallic thermometer is simultaneously connected to the main nitrogen pipeline and the molecular sieve cold blow pipeline.

[0018] Further, the waste nitrogen main pipeline includes a fractionating column and a regulating valve for the waste nitrogen main pipeline. One end of the regulating valve for the waste nitrogen main pipeline is connected to the fractionating column, and the other end of the regulating valve for the waste nitrogen main pipeline is simultaneously connected to the second bimetal thermometer and the molecular sieve cold blow pipeline.

[0019] Further, the molecular sieve cold blow pipeline includes a cold blow regulating valve. One end of the cold blow regulating valve is simultaneously connected to the regulating valve for the waste nitrogen main pipeline, the second bimetal thermometer, and the regulating valve before the waste nitrogen enters the electric heater, and the other end of the cold blow regulating valve is connected to the molecular sieve purifier.

[0020] Further, the regeneration gas generation pipeline includes a first temperature and pressure detection mechanism, a vacuum breaker, a second regulating valve, and a waste nitrogen bypass vent pipeline. One end of the first temperature and pressure detection mechanism is connected to the plate heat exchanger, and the other end of the first temperature and pressure detection mechanism is connected to the vacuum breaker. The vacuum breaker is also simultaneously connected to the second regulating valve and the waste nitrogen bypass vent pipeline; the second regulating valve is connected to the electric heater.

[0021] Further, the waste nitrogen bypass vent pipeline includes a third regulating valve and a discharge silencer. One end of the third regulating valve is simultaneously connected to the vacuum breaker and the second regulating valve, and the other end of the third regulating valve is connected to the discharge silencer.

[0022] Further, the cooling pipeline includes a cooling water pipeline and a circulating water pipeline. The cooling water pipeline and the circulating water pipeline are simultaneously connected to the air cooling tower;

[0023] The cooling water pipeline includes a cooling water pump and a chiller. One end of the cooling water pump is connected to the air cooling tower, and the other end of the cooling water pump is connected to the chiller;

[0024] The circulating water pipeline includes a normal temperature water pump and a circulating water system. One end of the normal temperature water pump is connected to the air cooling tower, and the other end of the normal temperature water pump is connected to the circulating water system.

[0025] In the present invention, the air exchanges heat with the waste nitrogen through the heat exchange system to recover the cold energy of the waste nitrogen, which can reduce the temperature of the air entering the air cooling tower, thereby reducing the water consumption of the normal temperature water and low temperature water in the air cooling tower, and at the same time reducing the power consumption of the chilled water unit; the waste nitrogen exchanges heat with the air through the heat exchange system to recover the heat of the air, which can increase the temperature of the waste nitrogen entering the molecular sieve, thereby reducing the power consumption of the electric heater of the molecular sieve; the inlet and outlet temperatures and pressures of the heat exchanger are integrated into the DCS system, and through the setting of safety interlocks, the safety and stability of the heat exchange system are ensured;. In view of the large differences in temperature, flow rate, pressure, etc. between the two fluids, through the design of differentiated flow channel geometric parameters and flow paths, the heat transfer efficiency is maximized and the pressure drop is optimized; for the outlet temperature of the waste nitrogen, an upper limit and a lower limit temperature are respectively set, and when the upper limit or lower limit temperature is reached, the opening degree of the air side valve is controlled correspondingly by the DCS to improve the heat exchange efficiency. Brief Description of the Drawings

[0026] Figure 1 It is a structural schematic diagram of the air separation pre-cooling heat exchange system provided by the present invention;

[0027] Figure 2 It is a control logic diagram of the air separation pre-cooling heat exchange system provided by the present invention.

[0028] The corresponding reference numerals should be: 1. Self-cleaning filter, 2. Air compressor, 3. Main pipeline for the air from the air compressor outlet to the air cooling tower, 4. Bypass pipeline for the air from the air compressor outlet to the heat exchanger, 5. Regulating valve for the high-temperature air bypass pipeline, 6. Regulating valve for the high-temperature air main pipeline, 7. Buffer tank, 8. Pressure gauge, 9. First bimetallic thermometer, 10. Plate heat exchanger, 11. Regulating valve for the waste nitrogen inlet, 12. Second bimetallic thermometer, 13. Molecular sieve cold blow pipeline, 14. Regulating valve for the waste nitrogen main pipeline, 15. Fractionating tower, 16. Regulating valve before the waste nitrogen enters the electric heater, 17. Electric heater, 18. Molecular sieve purifier, 19. First temperature and pressure detection mechanism, 20. Second temperature and pressure detection mechanism, 21. Vacuum breaker, 22. Discharge silencer, 23. Air cooling tower, 24. Cooling water pump, 25. Normal temperature water pump, 26. Chilled water unit, 27. Circulating water system, 28. Waste nitrogen main pipeline, 29. Cold blow regulating valve, 30. Waste nitrogen bypass branch pipe, 31. First regulating valve, 32. Second regulating valve, 33. Third regulating valve. Detailed Description of the Invention

[0029] An embodiment of the present invention provides an air separation pre-cooling and heat exchange system, including: a self-cleaning filter, an air compressor, a main pipeline for the air discharged from the air compressor to the air cooling tower, a bypass pipeline for the air discharged from the air compressor to the heat exchanger, a plate heat exchanger, a main waste nitrogen pipeline, a molecular sieve cold blow pipeline, a waste nitrogen bypass branch, a regeneration gas generation pipeline, a cooling pipeline, a second temperature and pressure detection mechanism, a first regulating valve, an air cooling tower, a regulating valve before the waste nitrogen enters the electric heater, an electric heater, a molecular sieve purifier, and a cooling water pump; the self-cleaning filter is connected to the air compressor, and the air compressor is simultaneously connected to the main pipeline for the air discharged from the air compressor to the air cooling tower and the bypass pipeline for the air discharged from the air compressor to the heat exchanger; the main pipeline for the air discharged from the air compressor to the air cooling tower is connected to the air cooling tower; the bypass pipeline for the air discharged from the air compressor to the heat exchanger is connected to the plate heat exchanger, and the first port of the plate heat exchanger, the second temperature and pressure detection mechanism, the first regulating valve, and the air cooling tower are sequentially connected; the second port of the plate heat exchanger is connected to the regeneration gas generation pipeline, and the third port of the plate heat exchanger is connected to the waste nitrogen bypass branch; the air cooling tower is connected to the cooling pipeline, and the air cooling tower is also connected to the molecular sieve purifier through the cooling water pump; the regeneration gas generation pipeline is connected to the electric heater, and the electric heater is connected to the molecular sieve purifier; the waste nitrogen bypass branch is simultaneously connected to the main waste nitrogen pipeline and the molecular sieve cold blow pipeline, and the molecular sieve cold blow pipeline is connected to the molecular sieve purifier; the front end of the molecular sieve cold blow pipeline is connected to the electric heater through the regulating valve before the waste nitrogen enters the electric heater. The main purpose of the present invention is to solve the problems in the prior art that the high-temperature air discharged from the air compressor directly goes to the air cooling tower for cooling, and this part of the heat is not utilized, and at the same time, the waste nitrogen of the molecular sieve is directly heated by the heater, and the cold quantity of this part of the waste nitrogen is not effectively utilized.

[0030] Terms such as "first", "second", "third", "fourth", etc. (if any) in the specification, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "comprising" or "having" and any variation thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] For ease of understanding, the specific process of the embodiment of the present invention is described below. The embodiment of the air separation pre-cooling and heat exchange system provided by the present invention includes:

[0032] Self-cleaning filter, air compressor, main pipeline for the air from the air compressor outlet to the air cooling tower, bypass pipeline for the air from the air compressor outlet to the heat exchanger, plate heat exchanger, main pipeline for waste nitrogen, molecular sieve cold blow pipeline, waste nitrogen bypass branch, regeneration gas generation pipeline, cooling pipeline, second temperature and pressure detection mechanism, first regulating valve, air cooling tower, regulating valve before the waste nitrogen enters the electric heater, electric heater, molecular sieve purifier, and cooling water pump;

[0033] The self-cleaning filter is connected to the air compressor, and the air compressor is simultaneously connected to the main pipeline for the air from the air compressor outlet to the air cooling tower and the bypass pipeline for the air from the air compressor outlet to the heat exchanger; the main pipeline for the air from the air compressor outlet to the air cooling tower is connected to the air cooling tower; the bypass pipeline for the air from the air compressor outlet to the heat exchanger is connected to the plate heat exchanger, and the first port of the plate heat exchanger, the second temperature and pressure detection mechanism, the first regulating valve, and the air cooling tower are connected in sequence; the second port of the plate heat exchanger is connected to the regeneration gas generation pipeline, and the third port of the plate heat exchanger is connected to the waste nitrogen bypass branch;

[0034] The air cooling tower is connected to the cooling pipeline, and the air cooling tower is also connected to the molecular sieve purifier through the cooling water pump;

[0035] The regeneration gas generation pipeline is connected to the electric heater, and the electric heater is connected to the molecular sieve purifier;

[0036] The waste nitrogen bypass branch is simultaneously connected to the main pipeline for waste nitrogen and the molecular sieve cold blow pipeline, and the molecular sieve cold blow pipeline is connected to the molecular sieve purifier;

[0037] The front end of the molecular sieve cold blow pipeline is connected to the electric heater through the regulating valve before the waste nitrogen enters the electric heater.

[0038] The main pipeline for the air from the air compressor outlet to the air cooling tower includes a regulating valve for the high-temperature air main pipeline. One end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the air compressor and the bypass pipeline for the air from the air compressor outlet to the heat exchanger, and the other end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the first regulating valve and the air cooling tower.

[0039] The bypass pipeline for the air from the air compressor outlet to the heat exchanger includes: a regulating valve for the high-temperature air bypass pipeline, a buffer tank, a pressure gauge, and a first bimetallic thermometer. The regulating valve for the high-temperature air bypass pipeline, the buffer tank, the pressure gauge, and the first bimetallic thermometer are connected in sequence. The front end of the regulating valve for the high-temperature air bypass pipeline is simultaneously connected to the air compressor and the regulating valve for the high-temperature air main pipeline, and the first bimetallic thermometer is connected to the plate heat exchanger.

[0040] The nitrogen purge bypass branch pipe includes: a nitrogen purge inlet regulating valve and a second bimetal thermometer. One end of the nitrogen purge inlet regulating valve is connected to the plate heat exchanger, and the other end of the nitrogen purge inlet regulating valve is connected to the second bimetal thermometer. The second bimetal thermometer is simultaneously connected to the main nitrogen purge pipeline and the molecular sieve cold blow pipeline.

[0041] The main nitrogen purge pipeline includes a fractionating tower and a main nitrogen purge pipeline regulating valve. One end of the main nitrogen purge pipeline regulating valve is connected to the fractionating tower, and the other end of the main nitrogen purge pipeline regulating valve is simultaneously connected to the second bimetal thermometer and the molecular sieve cold blow pipeline.

[0042] The molecular sieve cold blow pipeline includes a cold blow regulating valve. One end of the cold blow regulating valve is simultaneously connected to the main nitrogen purge pipeline regulating valve, the second bimetal thermometer, and the nitrogen purge inlet regulating valve before the electric heater. The other end of the cold blow regulating valve is connected to the molecular sieve purifier.

[0043] The regeneration gas generation pipeline includes a first temperature and pressure detection mechanism, a vacuum breaker, a second regulating valve, and a nitrogen purge bypass vent pipeline. One end of the first temperature and pressure detection mechanism is connected to the plate heat exchanger, and the other end of the first temperature and pressure detection mechanism is connected to the vacuum breaker. The vacuum breaker is also simultaneously connected to the second regulating valve and the nitrogen purge bypass vent pipeline; the second regulating valve is connected to the electric heater.

[0044] The nitrogen purge bypass vent pipeline includes a third regulating valve and a discharge silencer. One end of the third regulating valve is simultaneously connected to the vacuum breaker and the second regulating valve, and the other end of the third regulating valve is connected to the discharge silencer.

[0045] The cooling pipeline includes a cooling water pipeline and a circulating water pipeline. The cooling water pipeline and the circulating water pipeline are simultaneously connected to the air cooling tower;

[0046] The cooling water pipeline includes a cooling water pump and a chiller. One end of the cooling water pump is connected to the air cooling tower, and the other end of the cooling water pump is connected to the chiller;

[0047] The circulating water pipeline includes a normal temperature water pump and a circulating water system. One end of the normal temperature water pump is connected to the air cooling tower, and the other end of the normal temperature water pump is connected to the circulating water system.

[0048] Specific implementation plan:

[0049] First, the raw material air is filtered by the self-cleaning filter 1 to remove dust and mechanical impurities. The filtered air enters the air compressor 2 for compression. After compression, the air pressure is about 450 Kpa and the temperature is about 90°C. The original process flow is that the air at the outlet of the air compressor goes to the main pipeline 3 of the air cooling tower and enters the air cooling tower 23 for cooling. After cooling from 90°C to about 14°C, it enters the subsequent process flow. In the present invention, a bypass pipeline 4 for the air at the outlet of the air compressor to the heat exchanger is added to the main pipeline 3 of the air at the outlet of the air compressor to the air cooling tower. The high-temperature air enters the plate heat exchanger 10 through the bypass pipeline 4 for the air at the outlet of the air compressor to the heat exchanger. At the same time, a bypass pipeline regulating valve 5 is provided on the bypass branch pipe to regulate the flow rate of the air entering the heat exchanger. The buffer tank 7 performs dynamic pressure buffering to suppress pressure fluctuations. The temperature and pressure of the air before entering the heat exchanger are monitored by the pressure gauge 8 and the first bimetallic thermometer 9, and the temperature and pressure data are uploaded to the DCS system through sensors.

[0050] On the other hand, the waste nitrogen is led out from the upper part of the fractionating tower 15. The outlet temperature of the waste nitrogen is about 20°C. In the original process flow, during the molecular sieve heating stage, the waste nitrogen enters the electric heater through the main waste nitrogen pipeline 28 and is heated to about 170°C and then enters the molecular sieve bed for thermal blowing desorption regeneration. During the cold blowing stage, the molecular sieve bed is directly cold blown through the bypass pipeline without passing through the electric heater. In the present invention, a bypass branch pipe for the waste nitrogen to enter the heat exchanger 10 is provided, and a waste nitrogen inlet regulating valve 11 is provided on the branch pipe. When the molecular sieve is in the heating stage, the waste nitrogen enters the plate heat exchanger 10 through the bypass branch pipe 30 of the waste nitrogen to exchange heat with the high-temperature air. When the molecular sieve is in the cold blowing stage, the waste nitrogen does not pass through the heat exchanger and the electric heater. The waste nitrogen inlet regulating valve 11 is fully closed, and the regulating valve 16 before the waste nitrogen enters the electric heater is fully closed. The waste nitrogen directly enters the molecular sieve from the molecular sieve cold blowing pipeline for cold blowing.

[0051] Through two bypass branch pipes on both sides, high-temperature air and low-temperature waste nitrogen are introduced into the plate heat exchanger for heat exchange. After the air exits the heat exchanger, it is merged into the main process pipeline and enters the air cooling tower for cooling. The air after heat exchange can significantly reduce the inlet temperature of the air cooling tower, thereby reducing the cooling water consumption and the power consumption of the chiller. After the waste nitrogen exits the heat exchanger, it enters the electric heater 17 for heating, and then enters the molecular sieve hot blow bed for regeneration. After the air exits the heat exchanger, the temperature and pressure 20 of the air exiting the heat exchanger are monitored. The differences between the pressure 8 and temperature 9 of the air before entering the heat exchanger and the temperature and pressure 20 at the outlet are interlocked and controlled on the DCS. When it is greater than 50 kPa, the regulating valves 5 of the high-temperature air bypass pipeline, the regulating valve 11 of the waste nitrogen inlet, and the first regulating valve 31 are all closed. At this time, the air side and the waste nitrogen side are switched to the full main pipeline mode, and the operation is carried out according to the original process flow, and the heat exchanger stops working. The difference between the waste nitrogen inlet temperature detected by the second bimetal thermometer 12 and the waste nitrogen outlet temperature detected by the first temperature and pressure detection mechanism 19 is interlocked and controlled. When the temperature difference is less than 5 °C, the heat exchange efficiency of the heat exchanger is poor at this time, and it is immediately switched to the standby heat exchanger, and an alarm signal is sent to remind the maintenance personnel to repair the original heat exchanger and pipeline. In addition, the pressure of the waste nitrogen exiting the heat exchanger needs to be monitored to prevent excessive pressure drop from causing negative pressure in the outlet pipeline, and a vacuum breaker 21 is set to prevent the pipeline from collapsing. For the coordination between the two interlocks, the differential pressure interlock on the air side should be triggered first because it directly threatens the structural safety of the system.

[0052] In addition, another interlock control is set for the waste nitrogen outlet temperature: when the waste nitrogen outlet temperature 19 ≤ 65 °C, the opening degree of the regulating valve 5 of the high-temperature air bypass pipeline is increased to increase the heat exchange amount on the air side; when the waste nitrogen outlet temperature 19 is greater than 65 °C and less than 75 °C, the opening degree of the regulating valve 5 remains unchanged; when the waste nitrogen outlet temperature ≥ 75 °C, the opening degree of the regulating valve 5 is reduced to reduce the heat exchange amount on the air side. Through the above operations, the heat balance of the heat exchanger is ensured, and the cross of the fluid temperatures on both sides is prevented, resulting in reverse heat transfer.

[0053] For the four processes of pressure reduction, heating, cold blow, and pressure increase in the molecular sieve regeneration, during the pressure reduction and pressure increase processes, the regulating valve 16 before the waste nitrogen enters the electric heater and the cold blow regulating valve 29 are all closed, and the waste nitrogen passes through the third regulating valve 33 after heat exchange in the plate heat exchanger 10 and is discharged through the relief silencer 22. During the heating process, the regulating valve 16 before the waste nitrogen enters the electric heater and the cold blow regulating valve 29 are all closed, and the waste nitrogen passes through the second regulating valve 32 after heat exchange in the heat exchanger 10 and enters the electric heater for further heating, and then enters the molecular sieve bed for hot blow. During the cold blow process, the regulating valve 11 of the waste nitrogen entering the heat exchanger and the regulating valve 16 before the waste nitrogen enters the electric heater are all closed, and the waste nitrogen passes through the main waste nitrogen pipeline 28, through the cold blow regulating valve 29, and directly enters the molecular sieve to desorb and regenerate the bed layer.

[0054] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, or units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0055] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An air separation pre-cooling and heat exchange system, characterized in that, Including: Self-cleaning filter, air compressor, main pipeline for air from the air compressor outlet to the air cooling tower, bypass pipeline for air from the air compressor outlet to the heat exchanger, plate heat exchanger, main pipeline for waste nitrogen, molecular sieve cold blow pipeline, waste nitrogen bypass branch, regeneration gas generation pipeline, cooling pipeline, second temperature and pressure detection mechanism, first regulating valve, air cooling tower, regulating valve before waste nitrogen enters the electric heater, electric heater, molecular sieve purifier, and cooling water pump; The self-cleaning filter is connected to the air compressor, and the air compressor is simultaneously connected to the main pipeline for air from the air compressor outlet to the air cooling tower and the bypass pipeline for air from the air compressor outlet to the heat exchanger; the main pipeline for air from the air compressor outlet to the air cooling tower is connected to the air cooling tower; the bypass pipeline for air from the air compressor outlet to the heat exchanger is connected to the plate heat exchanger, and the first port of the plate heat exchanger, the second temperature and pressure detection mechanism, the first regulating valve, and the air cooling tower are connected in sequence; the second port of the plate heat exchanger is connected to the regeneration gas generation pipeline, and the third port of the plate heat exchanger is connected to the waste nitrogen bypass branch; The air cooling tower is connected to the cooling pipeline, and the air cooling tower is also connected to the molecular sieve purifier through the cooling water pump; The regeneration gas generation pipeline is connected to the electric heater, and the electric heater is connected to the molecular sieve purifier; The waste nitrogen bypass branch is simultaneously connected to the main pipeline for waste nitrogen and the molecular sieve cold blow pipeline, and the molecular sieve cold blow pipeline is connected to the molecular sieve purifier; The front end of the molecular sieve cold blow pipeline is connected to the electric heater through the regulating valve before waste nitrogen enters the electric heater.

2. The air separation pre-cooling and heat exchange system according to claim 1, characterized in that The main pipeline for air from the air compressor outlet to the air cooling tower includes a regulating valve for the high-temperature air main pipeline. One end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the air compressor and the bypass pipeline for air from the air compressor outlet to the heat exchanger, and the other end of the regulating valve for the high-temperature air main pipeline is simultaneously connected to the first regulating valve and the air cooling tower.

3. The air separation pre-cooling and heat exchange system according to claim 2, wherein, The bypass pipeline for air from the air compressor outlet to the heat exchanger includes: a regulating valve for the high-temperature air bypass pipeline, a buffer tank, a pressure gauge, and a first bimetallic thermometer. The regulating valve for the high-temperature air bypass pipeline, the buffer tank, the pressure gauge, and the first bimetallic thermometer are connected in sequence. The front end of the regulating valve for the high-temperature air bypass pipeline is simultaneously connected to the air compressor and the regulating valve for the high-temperature air main pipeline, and the first bimetallic thermometer is connected to the plate heat exchanger.

4. The air separation pre-cooling and heat exchange system according to claim 3, characterized in that, The waste nitrogen bypass branch includes: a waste nitrogen inlet regulating valve and a second bimetallic thermometer. One end of the waste nitrogen inlet regulating valve is connected to the plate heat exchanger, the other end of the waste nitrogen inlet regulating valve is connected to the second bimetallic thermometer, and the second bimetallic thermometer is simultaneously connected to the main pipeline for waste nitrogen and the molecular sieve cold blow pipeline.

5. The air separation pre-cooling and heat exchange system according to claim 4, wherein The main pipeline for waste nitrogen includes a fractionating tower and a regulating valve for the main pipeline for waste nitrogen. One end of the regulating valve for the main pipeline for waste nitrogen is connected to the fractionating tower, and the other end of the regulating valve for the main pipeline for waste nitrogen is simultaneously connected to the second bimetallic thermometer and the molecular sieve cold blow pipeline.

6. The air separation pre-cooling and heat exchange system according to claim 5, characterized in that, The molecular sieve cold blow pipeline includes a cold blow regulating valve. One end of the cold blow regulating valve is simultaneously connected to the waste nitrogen main pipeline regulating valve, the second bimetal thermometer, and the waste nitrogen regulating valve before entering the electric heater, and the other end of the cold blow regulating valve is connected to the molecular sieve purifier.

7. The air separation pre-cooling and heat exchange system according to claim 6, wherein The regeneration gas generation pipeline includes a first temperature and pressure detection mechanism, a vacuum breaker, a second regulating valve, and a waste nitrogen bypass vent pipeline. One end of the first temperature and pressure detection mechanism is connected to the plate heat exchanger, and the other end is connected to the vacuum breaker. The vacuum breaker is also simultaneously connected to the second regulating valve and the waste nitrogen bypass vent pipeline; the second regulating valve is connected to the electric heater.

8. The air separation pre-cooling and heat exchange system according to claim 7, characterized in that The waste nitrogen bypass vent pipeline includes a third regulating valve and a discharge silencer. One end of the third regulating valve is simultaneously connected to the vacuum breaker and the second regulating valve, and the other end of the third regulating valve is connected to the discharge silencer.

9. The air separation pre-cooling and heat exchange system according to claim 8, characterized in that, The cooling pipeline includes a cooling water pipeline and a circulating water pipeline, and the cooling water pipeline and the circulating water pipeline are simultaneously connected to the air cooling tower; The cooling water pipeline includes a cooling water pump and a chiller. One end of the cooling water pump is connected to the air cooling tower, and the other end is connected to the chiller; The circulating water pipeline includes a normal temperature water pump and a circulating water system. One end of the normal temperature water pump is connected to the air cooling tower, and the other end is connected to the circulating water system.

Images