Double-tower backflow air separation plant with high nitrogen and high-purity oxygen

Abstract

The utility model discloses double-tower backflow high-nitrogen and high-purity oxygen air separation equipment which comprises a cold box, a main heat exchanger, a first upper tower and a first lower tower, the cold box is connected with a gas inlet pipe, one end of the gas inlet pipe is arranged in the cold box, the gas inlet pipe penetrates through the main heat exchanger and is connected with the bottom of the first lower tower, and a second lower tower is installed on the upper portion of the first lower tower. A first main condensation evaporator is installed in the second lower tower, the side wall of the top of the first lower tower is connected with the input end of the first main condensation evaporator through a pipeline, a first backflow pipe is installed at the output end of the second main condensation evaporator, one end of the first backflow pipe is connected with the side wall of the top of the first lower tower, and an output pipe is further installed between the second lower tower and the first upper tower. A second upper tower and an oxygen tower are sequentially installed on the top of the first upper tower, a second liquid air pipe is installed on the side wall of the bottom of the first upper tower, and the end, away from the first upper tower, of the second liquid air pipe is connected with the oxygen tower. The problems that existing equipment cannot produce pure oxygen and pure nitrogen at the same time, and the production cost is high are solved.

Description

Technical Field

[0001] The utility model relates to an air separation device, in particular to an air separation device with a double-tower reflux high-nitrogen and high-purity oxygen. Background Art

[0002] With the rapid development of the electronics industry and chips, the demand for high-purity oxygen has also increased rapidly. For example, in the photovoltaic industry, while high-purity nitrogen is needed, a small amount of high-purity oxygen is also required. In the traditional single-tower and double-tower processes for high-purity nitrogen, an oxygen tower is usually not provided, so it is difficult to directly prepare high-purity oxygen, and the cost of using the chemical method is relatively high. Therefore, it is necessary to design a device that can produce high-purity nitrogen and high-purity oxygen simultaneously, which not only reduces the equipment investment cost but also greatly reduces the energy consumption and improves the product added value.

[0003] In order to overcome the defects existing in the prior art, this patent provides a double-tower reflux high-nitrogen device with high-purity oxygen. On the basis of the original double-tower reflux high-nitrogen, an oxygen enrichment tower is added to the main condenser of the upper tower and connected to the main condenser of the upper tower to realize the reuse of oxygen-rich air, so as to realize the simultaneous production of high-purity nitrogen and high-purity oxygen by one device. A solution is proposed for the above problems. Summary of the Utility Model

[0004] The purpose of the utility model is to provide an air separation device with a double-tower reflux high-nitrogen and high-purity oxygen, which solves the problems raised in the above background art.

[0005] The above technical purpose of the utility model is achieved through the following technical solutions:

[0006] An air separation plant with a double-tower reverse flow, high nitrogen content and high-purity oxygen, comprising a cold box and a main heat exchanger, an upper tower 1 and a lower tower 1 installed in the cold box. The cold box is connected with a gas inlet pipe. One end of the gas inlet pipe is arranged inside the cold box. The gas inlet pipe passes through the main heat exchanger and is connected to the bottom of the lower tower 1. An upper part of the lower tower 1 is installed with a lower tower 2. An exhaust pipe 1 is also installed on the top side wall of the lower tower 1. The exhaust pipe 1 passes through the main heat exchanger and exits the cold box. A main condenser-evaporator 1 is installed in the lower tower 2. The top side wall of the lower tower 1 is connected to the input end of the main condenser-evaporator 1 through a pipe. The output end of the main condenser-evaporator 1 is installed with a reflux pipe 1. One end of the reflux pipe 1 is connected to the top side wall of the lower tower 1. An output pipe is also installed between the lower tower 2 and the upper tower 1. A liquid air throttle valve 2 is installed on the output pipe. An upper tower 2 and an oxygen tower are successively installed on the top of the upper tower 1. A liquid air pipe 2 is installed on the bottom side wall of the upper tower 1. One end of the liquid air pipe 2 far away from the upper tower 1 is connected to the oxygen tower. A liquid air throttle valve 3 is installed on the liquid air pipe 2. A main condenser-evaporator 2 is installed in the upper tower 2. The top side wall of the upper tower 1 is connected to the input end of the main condenser-evaporator 2 through a pipe. The output end of the main condenser-evaporator 2 is installed with a reflux pipe 2. One end of the reflux pipe 2 is connected to the top side wall of the upper tower 2. An outlet pipe is installed on the bottom side wall of the upper tower 2. A liquid oxygen pump is connected to the outlet pipe. The outlet pipe passes through the main heat exchanger and exits the cold box.

[0007] Preferably, an exhaust pipe 2 is connected to the top of the lower tower 2. A shunt is provided at one end of the exhaust pipe 2 far away from the lower tower 2. One end of the exhaust pipe 2 is connected to two expansion machines 2. The outlet ends of the two expansion machines 2 are connected with a common vent pipe 2. The vent pipe 2 passes through the main heat exchanger and exits the cold box. The other end of the exhaust pipe 2 is connected to the side wall of the upper tower 1.

[0008] Preferably, a liquid air pipe 1 is connected between the bottom of the lower tower 1 and the upper part of the lower tower 2. A liquid air throttle valve 1 is installed on the liquid air pipe 1.

[0009] Preferably, a shunt pipe is installed on the reflux pipe 2. The shunt pipe is connected to two liquid nitrogen pumps. The two liquid nitrogen pumps are connected to the reflux pipe 1 through pipes.

[0010] Preferably, a connecting pipe is shunted from the gas inlet pipe inside the main heat exchanger. One end of the connecting pipe is connected to a gas bearing expansion machine 1. The outlet end of the gas bearing expansion machine 1 is connected to a vent pipe 1. The vent pipe 1 passes through the main heat exchanger and exits the cold box.

[0011] Preferably, a waste nitrogen pipe is installed on the top of the oxygen tower. The waste nitrogen pipe is communicated with the vent pipe 2.

[0012] Preferably, a filter, an air compressor and a precooling unit are installed on the gas inlet pipe, and an adsorber is also connected to the gas inlet pipe.

[0013] Beneficial effects: The air separation device of the present application can produce high-purity nitrogen and high-purity oxygen simultaneously by arranging an oxygen tower on the upper tower, so as to meet the needs of different industrial fields. Compared with the traditional single-tower or double-tower processes, this device can reduce the cost of producing high-purity oxygen, avoid the high cost of purifying oxygen by chemical methods, and the overall investment cost of the device is also correspondingly reduced due to the simplification of the process flow and the reduction of energy consumption. Description of the Drawings

[0014] Figure 1 FIG. [Example number] is a schematic diagram showing the internal structure of the cold box;

[0015] Figure 2 FIG. [Example number] is a schematic diagram showing the overall structure of the device.

[0016] Reference numerals: 1. Cold box; 2. Main heat exchanger; 3. Upper tower 1; 4. Lower tower 1; 5. Gas inlet pipe; 6. Lower tower 2; 7. Exhaust pipe 1; 8. Main condenser-evaporator 1; 9. Return pipe 1; 10. Output pipe; 11. Liquid air throttle valve 2; 12. Upper tower 2; 13. Oxygen tower; 14. Liquid air pipe 2; 15. Main condenser-evaporator 2; 16. Return pipe 2; 17. Liquid outlet pipe; 18. Liquid oxygen pump; 19. Exhaust pipe 2; 20. Expander 2; 21. Vent pipe 2; 22. Liquid air pipe 1; 23. Liquid air throttle valve 1; 24. Shunt pipe; 25. Liquid nitrogen pump; 26. Connecting pipe; 27. Gas-bearing expander 1; 28. Vent pipe 1; 29. Waste nitrogen pipe; 30. Filter; 31. Air compressor; 32. Precooling unit; 33. Adsorber; 34. Liquid air throttle valve 3. Detailed Embodiments

[0017] See Figures 1 to 2As shown, a double-tower reflux high-nitrogen with high-purity oxygen air separation equipment includes a cold box 1 and a main heat exchanger 2, an upper tower 3 and a lower tower 4 installed in the cold box 1. The cold box 1 is an integral skid-mounted structure. The cold box 1 is integrally skid-mounted. The equipment is exquisite and compact, and can be made into a vehicle-mounted air separation equipment, which is convenient for domestic overall transportation and saves transportation and on-site installation costs. The cold box 1 is connected to a gas inlet pipe 5, and a filter 30, an air compressor 31 and a precooling unit 32 are installed on the gas inlet pipe 5. The gas inlet pipe 5 is also connected to an adsorber 33. One end of the gas inlet pipe 5 is arranged in the cold box 1, and the gas enters through the gas inlet pipe 5. When it enters the cold box 1, it will enter the filter 30, air compressor 31, precooling unit 32 and adsorber 33 in sequence. The raw air is sucked into the AF1 filter 30 to remove dust and other mechanical impurities, and then enters the AC1 air compressor 31 to be compressed to 0.88Mpa (G), cooled to ≤40℃ by the terminal cooler, and cooled to 5℃ by the RU1 precooling unit 32 to separate free water. It then enters the two adsorbers 33 to remove H2O, CO2, C2H2 and other hydrocarbons. After the purified air is extracted with a volume of 300Nm3 / h as instrument gas, the rest is sent to the FC1 cold box 1 for reaction.

[0018] After the gas inlet pipe 5 enters the cold box 1, it will be connected to the main heat exchanger 2. The gas inlet pipe 5 located inside the main heat exchanger 2 is divided into a connecting pipe 26. One end of the connecting pipe 26 is connected to a gas bearing expander 27. The outlet end of the gas bearing expander 27 is connected to a vent pipe 28. The vent pipe 28 passes through the main heat exchanger 2 and passes through the cold box 1. The main heat exchanger 2 is subsequently passed through the pipelines such as the reflux low-temperature dirty nitrogen, the low-temperature air after expansion, the product nitrogen and the product oxygen, and then passes through the gas inlet pipe 5 to exchange heat with it. After cooling, a part of the air is extracted from the middle of the main heat exchanger 2 and enters the auxiliary gas bearing expander 2. The low-temperature air after expansion is reheated in the main heat exchanger 2 and then discharged from the cold box 1. The gas inlet pipe 5 passes through the main heat exchanger 2 and is connected to the bottom of the lower tower 4. The lower tower 6 is installed on the upper part of the lower tower 4. An exhaust pipe 7 is also installed on the top side wall of the lower tower 4. The exhaust pipe 7 passes through the main heat exchanger 2 and passes through the cold box 1. The gas enters the bottom of the lower tower 4 through the gas inlet pipe 5. After distillation and separation, 0.8 MPa high-purity nitrogen will be obtained at the top of the lower tower 4, and oxygen-rich liquid air will be obtained at the bottom of the lower tower 4. The 0.8 MPa high-purity nitrogen will pass through the exhaust pipe 7 and then pass through the main heat exchanger 2 to pass through the cold box 1.

[0019] The bottom of the first lower column 4 is connected to the upper part of the second lower column 6 by a first liquid air pipe 22. A first liquid air throttle valve 23 is installed on the first liquid air pipe 22. A first main condenser-evaporator 8 is installed in the second lower column 6. The oxygen-rich liquid air in the first lower column 4 is transported downward to the second lower column 6 through the first liquid air pipe 22. The oxygen-rich liquid air is throttled through the liquid air throttle valve and enters the first main condenser-evaporator 8 in the second lower column 6 to exchange heat with nitrogen through phase change. The top side wall of the first lower column 4 is connected to the input end of the first main condenser-evaporator 8 through a pipeline. A first reflux pipe 9 is installed at the output end of the first main condenser-evaporator 8. One end of the first reflux pipe 9 is connected to the top side wall of the first lower column 4. After being condensed by the first main condenser-evaporator 8, nitrogen can be refluxed through the first reflux pipe 9 as the reflux liquid of the first lower column 4, or a part of the liquid nitrogen can be extracted as a product.

[0020] The top of the second lower column 6 is connected to a second exhaust pipe 19. One end of the second exhaust pipe 19 away from the second lower column 6 is provided with a shunt. One end of the second exhaust pipe 19 is connected to two second expanders 20. The outlet ends of the two second expanders 20 are connected to a connected second vent pipe 21. The second vent pipe 21 passes through the cold box 1 through the main heat exchanger 2. The other end of the second exhaust pipe 19 is connected to the side wall of the first upper column 3. The liquid air in the second lower column 6 evaporates into oxygen-rich air, and the gas enters the second exhaust pipe 19. A part of the gas enters the second expander 20 for expansion to supplement cold energy. The expanded low-temperature oxygen-rich air exchanges heat with air through the main heat exchanger 2 and then exits the cold box 1. A part of the gas is connected to two electric heaters, and the purification system is regenerated through the two electric heaters. The rest of the gas is all vented. The rest of the oxygen-rich air enters the first upper column 3 to participate in the second rectification. An output pipe 10 is also installed between the second lower column 6 and the first upper column 3. A second liquid air throttle valve 11 is installed on the output pipe 10. The liquid air in the main condenser-evaporator of the second lower column 6 will pass through the output pipe 10 and enter the bottom of the first upper column 3 through the liquid air throttle valve.

[0021] The first upper column 3 is successively installed with a second upper column 12 and an oxygen column 13 at the top. A second liquid air pipe 14 is installed on the bottom side wall of the first upper column 3. One end of the second liquid air pipe 14 away from the first upper column 3 is connected to the oxygen column 13. A third liquid air throttle valve 34 is installed on the second liquid air pipe 14. The liquid air at the bottom of the first upper column 3 is transported upward through the second liquid air pipe 14, throttled through the liquid air throttle valve, and enters the top of the oxygen column 13 as the reflux liquid of the oxygen column 13 to participate in the rectification of the oxygen column 13.

[0022] The main condenser-evaporator II 15 is installed in the upper column II 12. The top side wall of the upper column I 3 is connected to the input end of the main condenser-evaporator II 15 through a pipeline. The output end of the main condenser-evaporator II 15 is equipped with a reflux pipe II 16. One end of the reflux pipe II 16 is connected to the top side wall of the upper column II 12. The refined liquid reacts with the main condenser-evaporator in the upper column II 12 to obtain high-purity liquid oxygen, and undergoes phase change heat exchange with the nitrogen gas coming from the top of the upper column I 3. A waste nitrogen pipe 29 is installed at the top of the oxygen column 13. The waste nitrogen pipe 29 is communicated with the vent pipe II 21. Finally, the waste nitrogen gas at the top of the oxygen column 13 exits the cold box 1 after being reheated by the main heat exchanger 2 through the waste nitrogen pipe 29.

[0023] After condensation, a part of the nitrogen gas will be used as the upper column reflux liquid of the upper column I 3. A shunt pipe 24 is installed on the reflux pipe II 16. The shunt pipe 24 is connected to two liquid nitrogen pumps 25. The two liquid nitrogen pumps 25 are connected to the reflux pipe I 9 through pipelines. The rest is pressurized by the two liquid nitrogen pumps 25 and enters the top of the lower column I 4 as the reflux liquid of the lower column I 4, increasing the reflux ratio of the lower column I 4 to improve the extraction rate of nitrogen gas.

[0024] An outlet pipe 17 is installed on the bottom side wall of the upper column II 12. Through the outlet pipe 17, the liquid oxygen can be drawn out from the bottom of the main condenser-evaporator of the upper column II 12. The outlet pipe 17 is connected to a liquid oxygen pump 18. The outlet pipe 17 passes through the cold box 1 after passing through the main heat exchanger 2, is reheated after being pressurized by the liquid oxygen pump 18, and exits the cold box 1 at normal temperature to obtain high-purity oxygen at 0.8 MPa.

Claims

1. An air separation unit with a double-tower reflux high-nitrogen and high-purity oxygen, comprising a cold box (1), a main heat exchanger (2), an upper tower one (3), and a lower tower one (4) installed in the cold box (1), characterized in that, The cold box (1) is connected to a gas inlet pipe (5). One end of the gas inlet pipe (5) is arranged inside the cold box (1). The gas inlet pipe (5) passes through the main heat exchanger (2) and is connected to the bottom of the first lower column (4). The second lower column (6) is installed above the first lower column (4). An exhaust pipe one (7) is also installed on the top side wall of the first lower column (4). The exhaust pipe one (7) passes through the main heat exchanger (2) and exits the cold box (1). A first main condenser-evaporator (8) is installed inside the second lower column (6). The top side wall of the first lower column (4) is connected to the input end of the first main condenser-evaporator (8) through a pipeline. A first return pipe (9) is installed at the output end of the first main condenser-evaporator (8). One end of the first return pipe (9) is connected to the top side wall of the first lower column (4). An output pipe (10) is also installed between the second lower column (6) and the first upper column (3). A liquid air throttle valve two (11) is installed on the output pipe (10). The second upper column (12) and the oxygen column (13) are successively installed on the top of the first upper column (3). A second liquid air pipe (14) is installed on the bottom side wall of the first upper column (3). One end of the second liquid air pipe (14) away from the first upper column (3) is connected to the oxygen column (13). A liquid air throttle valve three (34) is installed on the second liquid air pipe (14). A second main condenser-evaporator (15) is installed inside the second upper column (12). The top side wall of the first upper column (3) is connected to the input end of the second main condenser-evaporator (15) through a pipeline. A second return pipe (16) is installed at the output end of the second main condenser-evaporator (15). One end of the second return pipe (16) is connected to the top side wall of the second upper column (12). An outlet pipe (17) is installed on the bottom side wall of the second upper column (12). A liquid oxygen pump (18) is connected to the outlet pipe (17). The outlet pipe (17) passes through the main heat exchanger (2) and exits the cold box (1).

2. The air separation device with a double-tower reverse flow, high-nitrogen and high-purity oxygen according to claim 1, characterized in that, An exhaust pipe two (19) is connected to the top of the second lower column (6). There is a shunt at one end of the exhaust pipe two (19) away from the second lower column (6). One end of the exhaust pipe two (19) is connected to two expanders two (20). The outlet ends of the two expanders two (20) are connected to a common vent pipe two (21). The vent pipe two (21) passes through the main heat exchanger (2) and exits the cold box (1). The other end of the exhaust pipe two (19) is connected to the side wall of the first upper column (3).

3. A double-column reverse-flow air separation plant with high nitrogen content and high-purity oxygen, characterized in that, A first liquid air pipe (22) is connected between the bottom of the first lower column (4) and the upper part of the second lower column (6). A liquid air throttle valve one (23) is installed on the first liquid air pipe (22).

4. The air separation device with high nitrogen and high-purity oxygen of double towers with reverse flow according to claim 1, characterized in that, A shunt pipe (24) is installed on the second return pipe (16). The shunt pipe (24) is connected to two liquid nitrogen pumps (25). The two liquid nitrogen pumps (25) are connected to the first return pipe (9) through a pipeline.

5. A double-column reverse-flow air separation plant with high nitrogen content and high-purity oxygen, characterized in that, The gas inlet pipe (5) in the main heat exchanger (2) is branched into a connecting pipe (26). One end of the connecting pipe (26) is connected to a gas-bearing expander I (27). The gas outlet end of the gas-bearing expander I (27) is connected to a vent pipe I (28). The vent pipe I (28) passes through the main heat exchanger (2) and penetrates out of the cold box (1).

6. The air separation device with high nitrogen and high-purity oxygen in a two-tower reverse flow according to claim 2, characterized in that A waste nitrogen pipe (29) is installed at the top of the oxygen tower (13). The waste nitrogen pipe (29) is communicated with the vent pipe II (21).

7. A double-column reverse-flow air separation plant with high nitrogen content and high-purity oxygen, as claimed in claim 1, wherein, A filter (30), an air compressor (31) and a precooling unit (32) are installed on the gas inlet pipe (5). An adsorber (33) is also connected to the gas inlet pipe (5).

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