A system for separating and recovering acetylene gas and nitrogen in the process of producing acetylene by calcium carbide method

Abstract

The utility model discloses an acetylene gas and nitrogen separation and recovery system in the production process of acetylene by calcium carbide method, comprising an exhaust gas pipeline, a washing tower group, a water ring vacuum pump, a buffer gas cabinet, a supercharger, a demister and a pressure swing adsorption device which are sequentially connected through pipelines, wherein the purified gas outlet of the pressure swing adsorption device is connected to the inlet of a nitrogen tank through a pipeline, the outlet of the nitrogen tank is connected to the exhaust gas pipeline, and the recovery gas outlet of the pressure swing adsorption device is connected to the acetylene gas recovery pipeline. The application solves the replacement waste gas generated in the unloading process of the wet acetylene generator, breaks through the environmental protection problem in safe production, and saves production costs; realizes zero emission of organic gas, and achieves the purpose of reducing production costs, energy saving and consumption reduction.

Description

Technical Field

[0001] The utility model relates to the technical field of separation and recovery of acetylene gas and nitrogen in the process of producing acetylene by calcium carbide method, in particular to an acetylene gas and nitrogen separation and recovery system in the process of producing acetylene by calcium carbide method. Background Art

[0002] Most domestic PVC manufacturers use the calcium carbide method to produce acetylene. The calcium carbide production process is divided into two categories: dry process and wet process. In the wet process, during the generation of acetylene, the generator is charged intermittently. During the charging process, the gas in the lower storage hopper will flow back into the upper storage hopper. In order to ensure the safety of charging, the upper storage hopper needs to be replaced with nitrogen before each charging, which produces a large amount of replacement waste gas. At present, most manufacturers directly vent the replacement waste gas. The mixed gas contains acetylene, nitrogen, calcium lime, etc. Directly discharging the replacement waste gas is not only risky, but also causes waste of resources and increased production costs. However, due to the characteristics of low pressure, large fluctuations, intermittent, and large amount of dust in the replacement waste gas of the acetylene generator, it brings difficulties to the recovery of acetylene and purification of exhaust gas. The details are as follows:

[0003] 1. Intermittent emission, usually only occurs in a specific time period before and after the upper storage hopper is replenished with calcium carbide. It has the characteristics of intermittent gas transmission and large instantaneous flow fluctuations.

[0004] 2. The pressure of the replaced waste gas is low and fluctuates. The partial pressure of the acetylene mixed gas is low, and the adsorption effect of conventional adsorbents is very poor. After treatment, it cannot meet the new national emission standards.

[0005] 3. The acetylene content fluctuates greatly in the early, middle and final stages of replacement, with an average content of more than 15%, and the rest is nitrogen and calcium carbonate. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide an acetylene gas and nitrogen separation and recovery system in the production process of acetylene by the calcium carbide process, which solves the replacement waste gas generated in the unloading process of the wet acetylene generator, breaks through the environmental protection problem in safe production, and saves production costs; realizes zero emission of organic gas, and achieves the purpose of reducing production costs and saving energy and reducing consumption.

[0007] The technical solution of the utility model for solving the above-mentioned technical problems is as follows: an acetylene gas and nitrogen separation and recovery system in the production process of acetylene by the calcium carbide process, comprising an exhaust gas pipeline, a washing tower group, a water ring vacuum pump, a buffer gas cabinet, a booster, a demister and a pressure swing adsorption device which are arranged in sequence and connected through pipelines, the purified gas outlet of the pressure swing adsorption device is connected to the inlet of a nitrogen tank through a pipeline, the outlet of the nitrogen tank is connected to the exhaust gas pipeline, and the recovery gas outlet of the pressure swing adsorption device is connected to the acetylene gas recovery pipeline.

[0008] The beneficial effects of adopting the above technical solution are:

[0009] It solves the problem of replacement waste gas generated during the unloading process of the wet acetylene generator, breaks through the environmental protection problem in safe production, and saves production costs; achieves zero emission of organic gas, and achieves the purpose of reducing production costs, saving energy and reducing consumption.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the washing tower group includes a washing tower 1 and a washing tower 2, the inlet of the washing tower 1 is connected to the exhaust gas pipeline, and the outlet thereof is connected to the inlet of the washing tower 2 through a pipeline, and the outlet of the washing tower 2 is connected to the water ring vacuum pump.

[0012] The beneficial effect of adopting the above further scheme is that multiple washings in the first washing tower and the second washing tower can remove dust in the exhaust gas.

[0013] Furthermore, the outlet of the nitrogen tank is connected to the exhaust gas pipe through a first displacement pipe, a nitrogen charging valve is provided on the first displacement pipe, one end of a second displacement pipe, one end of a third displacement pipe and a surplus nitrogen pipe are also connected to the first displacement pipe, the other end of the second displacement pipe is connected to the pipe between the outlet of the first washing tower and the inlet of the second washing tower, and the other end of the third displacement pipe is connected to the pipe between the water ring vacuum pump and the buffer gas tank.

[0014] The beneficial effect of adopting the above further scheme is that the pure nitrogen classified by the pressure swing adsorption device replaces the gas in the system through the first replacement pipeline, the second replacement pipeline and the third replacement pipeline respectively, thereby accelerating the recovery and separation of the gas, and the excess nitrogen is discharged into the storage tank from the surplus nitrogen pipeline.

[0015] Furthermore, a first circulation pipeline is installed on the first washing tower, and the two ends of the first circulation pipeline are respectively connected to the top and bottom of the first washing tower, a first circulation pump is installed on the first circulation pipeline, and the first circulation pipeline is also connected to a wastewater pipeline. A second circulation pipeline is also installed on the second washing tower, and the two ends of the second circulation pipeline are respectively connected to the top and bottom of the second washing tower, a second circulation pump is installed on the second circulation pipeline, and the second circulation pipeline is also connected to the first washing tower.

[0016] The beneficial effect of adopting the above further scheme is that circulating pumps are provided on both the first washing tower and the second washing tower, so that the washing water can be used multiple times, the washing efficiency is improved, and the cost is reduced.

[0017] Furthermore, it also includes a first reflux pipeline, one end of which is connected to the pipeline between the outlet of the second washing tower and the water ring vacuum pump, and the other end of which is connected to the pipeline between the water ring vacuum pump and the buffer gas tank. A first reflux regulating valve is provided on the first reflux pipeline, and an oxygen content detection meter and a cut-off valve are provided on the pipeline between the water ring vacuum pump and the buffer gas tank.

[0018] The beneficial effect of adopting the above further scheme is that when negative pressure occurs in the equipment in front of the water ring vacuum pump, the first reflux regulating valve can be opened to adjust the pressure in the system, and the oxygen content detection meter can detect the content of external air inhaled by the system's pipeline, thereby determining whether there is negative pressure in the system.

[0019] Furthermore, it also includes a second return pipe, one end of which is connected to the pipe between the buffer gas tank and the booster, and the other end of which is connected to the pipe between the booster and the demister, and a second return regulating valve is provided on the second return pipe.

[0020] The beneficial effect of adopting the above further solution is that the second reflux regulating valve can adjust the gas pressure in the pipeline between the booster and the demister.

[0021] Furthermore, a plurality of liquid level gauges are arranged at intervals on the top of the upper cabinet of the buffer gas tank.

[0022] The beneficial effect of adopting the above further solution is that the amount of gas in the buffer gas tank can be judged according to the liquid level meter, which is convenient for the staff to operate.

[0023] Furthermore, the pipeline between the water ring vacuum pump and the buffer gas tank is also connected with an exhaust pipeline, and the exhaust pipeline is provided with an exhaust valve.

[0024] The beneficial effect of adopting the above further solution is that excess gas can be discharged through the exhaust valve to ensure safety.

[0025] Furthermore, a sewage discharge pipe is provided at the bottom of the demister.

[0026] The beneficial effect of adopting the above further solution is that after the system has been running for a period of time, sewage can be discharged through the sewage pipe.

[0027] Furthermore, a pressure gauge is provided on the exhaust gas pipeline.

[0028] The beneficial effect of adopting the above further solution is that the pressure data in the exhaust gas pipeline can be read out through the pressure gauge. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the utility model.

[0030] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0031] 1. Waste gas pipeline; 2. First reflux regulating valve; 3. Oxygen content detection meter; 4. Shut-off valve; 5. Drain valve; 6. Nitrogen filling valve; 7. Hopper system; 8. Liquid level meter; 9. Second reflux regulating valve; 10. Washing tower 1; 11. Washing tower 2; 12. Water ring vacuum pump; 13. Buffer gas cabinet; 14. Booster; 15. Defogger; 16. Pressure swing adsorption device; 17. Nitrogen tank; 18. Second circulation pump; 19. First circulation pump; 20. Industrial water pipeline; 21. Fresh nitrogen pipeline; 22. Wastewater pipeline; 23. Surplus nitrogen pipeline; 24. Acetylene gas recovery pipeline; 25. First displacement pipeline; 26. Second displacement pipeline; 27. Third displacement pipeline; 28. First reflux pipeline; 29. ​​Second reflux pipeline; 30. Sewage pipeline. DETAILED DESCRIPTION

[0032] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0033] Embodiment 1:

[0034] like Figure 1 As shown, in this embodiment, an acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide method includes an exhaust gas pipeline 1, a washing tower group, a water ring vacuum pump 12, a buffer gas cabinet 13, a booster 14, a demister 15 and a pressure swing adsorption device 16 which are sequentially connected through pipelines, the purified gas outlet of the pressure swing adsorption device 16 is connected to the inlet of a nitrogen tank 17 through a pipeline, the outlet of the nitrogen tank 17 is connected to the exhaust gas pipeline 1, and the recovery gas outlet of the pressure swing adsorption device 16 is connected to the acetylene gas recovery pipeline 24.

[0035] The beneficial effects of this embodiment are as follows: the device collects the dust-containing gas discharged during the charging and replacement process of the acetylene generator, washes the particulate impurities, and then sends it to the dust-containing gas separation device for separation and transportation, the nitrogen is recovered and used in cascade, and the acetylene gas is recycled to the system, saving production costs.

[0036] When the device is in use, during the process of adding calcium carbide, the waste gas generated by the mixture of calcium lime and acetylene gas is in the feeding hopper 9, and is intermittently discharged through the fresh nitrogen pipeline 21 for nitrogen replacement. The replaced waste gas enters the first washing tower 10 and the second washing tower 11, and the impurities and calcium lime in the acetylene gas are washed by industrial water circulation, and then sent to the buffer gas cabinet 13 by the water ring vacuum pump 12. The buffered replacement gas is sent to the demister 15 by the booster 14 to remove moisture in the gas phase, and the clean acetylene gas enters the pressure swing adsorption device 16, and the acetylene gas and nitrogen are separated by the adsorbent. The separated acetylene gas is recycled, and the nitrogen enters the nitrogen tank 17 for buffering, and then is reused to the calcium carbide silo and the clean secondary sodium storage tank for nitrogen filling protection.

[0037] Among them, Figure 1 As described above, the industrial water in the industrial water pipeline 20 enters the second circulation pipeline, and enters the first washing tower 10 after circulating washing in the second washing tower 11, and the waste water generated is sent out by the circulation pump 19 of the first washing tower for recycling.

[0038] Among them, Figure 1 As shown, there can be multiple hopper systems 7, depending on actual work requirements.

[0039] Example 2

[0040] Preferably, on the basis of Example 1, the washing tower group includes a washing tower 10 and a washing tower 2 11, the inlet of the washing tower 10 is connected to the exhaust gas pipe 1, and the outlet thereof is connected to the inlet of the washing tower 2 11 through a pipe, and the outlet of the washing tower 2 11 is connected to the water ring vacuum pump 12.

[0041] The beneficial effect of this embodiment is that dust in the exhaust gas can be removed by multiple washings in the first washing tower 10 and the second washing tower 11, thereby ensuring the purification effect.

[0042] Furthermore, there can be multiple washing towers, and multiple washing towers can be connected in series to further enhance the purification effect.

[0043] Example 3

[0044] Preferably, on the basis of Example 2, the outlet of the nitrogen tank 17 is connected to the exhaust gas pipe 1 through a first displacement pipe 25, and a nitrogen charging valve 6 is provided on the first displacement pipe 25. The first displacement pipe 25 is also connected to one end of a second displacement pipe 26, one end of a third displacement pipe 27 and a surplus nitrogen pipe 23. The other end of the second displacement pipe 26 is connected to the pipe between the outlet of the first washing tower 10 and the inlet of the second washing tower 11, and the other end of the third displacement pipe 27 is connected to the pipe between the water ring vacuum pump 12 and the buffer gas cabinet 13.

[0045] The beneficial effect of this embodiment is that the pure nitrogen separated by the pressure swing adsorption device 16 replaces the gas in the system through the first replacement pipeline 25, the second replacement pipeline 26 and the third replacement pipeline 27 respectively, thereby accelerating the recovery and separation of the gas, and the excess nitrogen is discharged from the surplus nitrogen pipeline 23 into an external storage tank.

[0046] Example 4

[0047] Preferably, on the basis of Example 2-3, a first circulation pipeline is further installed on the first washing tower 10, and the two ends of the first circulation pipeline are respectively connected to the top and the bottom of the first washing tower 10, and a first circulation pump 19 is installed on the first circulation pipeline, and the first circulation pipeline is also connected to a wastewater pipeline 22, and a second circulation pipeline is also installed on the second washing tower 11, and the two ends of the second circulation pipeline are respectively connected to the top and the bottom of the second washing tower 11, and a second circulation pump 18 is installed on the second circulation pipeline, and the second circulation pipeline is also connected to the first washing tower 10.

[0048] The beneficial effect of this embodiment is that circulating pumps are provided on both the first washing tower 10 and the second washing tower 11, so that washing water can be used multiple times, thereby improving washing efficiency and reducing costs.

[0049] Furthermore, liquid level gauges are provided on both the first washing tower 10 and the second washing tower 11 to detect the liquid level, and valves can be provided on the wastewater pipe 22 to control the opening or closing of the valves according to the liquid level in the first washing tower 10.

[0050] Example 5

[0051] Preferably, on the basis of Examples 1-4, a first reflux pipe 28 is further included, one end of the first reflux pipe 28 is connected to the pipe between the outlet of the second washing tower 11 and the water ring vacuum pump 12, and the other end of the first reflux pipe 28 is connected to the pipe between the water ring vacuum pump 12 and the buffer gas tank 13, a first reflux regulating valve 2 is provided on the first reflux pipe 28, and an oxygen content detection meter 3 and a cut-off valve 4 are provided on the pipe between the water ring vacuum pump 12 and the buffer gas tank 13.

[0052] The beneficial effect of this embodiment is that when negative pressure occurs in the equipment in front of the water ring vacuum pump 12, the first reflux regulating valve 2 can be opened to adjust the pressure in the system, and the oxygen content detection meter 3 can detect the oxygen content of the outside air inhaled by the system's pipeline, thereby determining whether there is negative pressure in the system.

[0053] It should be noted that the pressure in the system is mainly regulated by the first reflux regulating valve 2, and the aforementioned replacement pipeline plays an auxiliary role in regulating the pressure in the system.

[0054] Example 6

[0055] Preferably, on the basis of Examples 1-5, a second return pipe 29 is further included, one end of the second return pipe 29 is connected to the pipe between the buffer gas tank 13 and the booster 14, and the other end thereof is connected to the pipe between the booster 14 and the demister 15, and a second return regulating valve 9 is provided on the second return pipe 29.

[0056] The beneficial effect of this embodiment is that the second reflux regulating valve 9 on the second reflux pipeline 29 can adjust the gas pressure in the pipeline between the supercharger 14 and the demister 15 .

[0057] Example 7

[0058] Preferably, on the basis of Embodiments 1-6, a plurality of liquid level gauges 8 are arranged at intervals on the top of the upper cabinet of the buffer gas cabinet 13 .

[0059] The beneficial effect of this embodiment is that the amount of gas in the buffer gas tank 13 is determined according to the liquid level meter, which is convenient for the staff to operate.

[0060] It should be noted that if Figure 1 As shown, there are three liquid level gauges 8, and the three liquid level gauges are radar level gauges. The height of the gas tank is measured by the three liquid level gauges, and the average value is taken to ensure the accuracy of the measured data.

[0061] Further, if Figure 1 As shown, the number of liquid level gauges 8 is three.

[0062] Furthermore, at least one venting flame arrester is provided on the top of the upper cabinet of the buffer gas tank 13, and when the liquid level reaches a certain height, it can be vented through an automatic venting pipeline.

[0063] Furthermore, the top of the upper cabinet of the buffer gas cabinet 13 is connected in sequence with a manual drain valve on the top of the gas cabinet, and manual draining can be performed when the buffer gas cabinet 13 needs to be repaired and replaced.

[0064] Furthermore, the bottom of the lower cabinet of the buffer gas tank 13 can be connected to the root valve of the gas tank level gauge and the gas tank drain valve, and the root valve of the gas tank level gauge is connected to the gas tank level gauge. Based on this technical solution, when it is necessary to inspect and drain water, it can be discharged through the drain valve, and the information of the gas tank level gauge can be used for alarm.

[0065] Furthermore, a hot water coil is provided inside the gas tank in the middle of the lower tank of the buffer gas tank 13. Based on this technical solution, in order to prevent the water in the gas tank from freezing in winter, a hot water coil is provided inside to heat the gas tank, thereby achieving the purpose of antifreeze.

[0066] Example 8

[0067] Preferably, on the basis of Embodiments 1-7, the pipeline between the water ring vacuum pump 12 and the buffer gas tank 13 is further connected with an exhaust pipeline, and the exhaust pipeline is provided with an exhaust valve 5.

[0068] The beneficial effect of this embodiment is that the exhaust valve 5 can discharge excess gas to ensure safety.

[0069] Example 9

[0070] Preferably, based on Examples 1-8, a sewage pipe 30 is provided at the bottom of the demister 15 .

[0071] The beneficial effect of this embodiment is that after the system has been running for a period of time, sewage can be discharged through the sewage pipe 30.

[0072] Example 10

[0073] Preferably, based on Embodiments 1-9, a pressure gauge is provided on the exhaust gas pipe 1.

[0074] The beneficial effect of this embodiment is that the pressure gauge is convenient for detecting the gas pressure in the exhaust gas pipeline 1 .

[0075] The main valve control principle of this utility model:

[0076] 1. When the pressure in the exhaust gas pipeline 1 is ≤1 kPa, open the first reflux regulating valve 2;

[0077] 2. When the oxygen content detection table 3 is ≥2%, close the cut-off valve 4 at the inlet of the buffer gas tank 13, open the drain valve 5 and the nitrogen filling valve 6; and operate the hopper system 7.

[0078] 3. When the buffer gas tank level gauge 8 (3 out of 2) ≥ 85%, open the drain valve 5; when the buffer gas tank level gauge 8 (3 out of 2) ≤ 70%, close the drain valve 5.

[0079] 4. When the buffer gas tank level gauge 8 (choose 2 from 3) ≤ 20%, open the second reflux regulating valve 9.

[0080] The main breakthrough technologies of this utility model are as follows:

[0081] 1. Dust-containing gas collection, washing and condensation technology;

[0082] 2. Separation technology of organic gas and nitrogen;

[0083] 3. Organic gas and nitrogen recovery technology;

[0084] Based on the annual production capacity of 300,000 tons of PVC, the following estimates are made: about 161.42 tons of acetylene gas is recovered per year, about 3.2397 million cubic meters of nitrogen is recovered per year, the cost is saved by 2.5122 million yuan per year, the electricity cost is consumed by about 347,200 yuan per year, and the actual annual production cost savings are about 2.165 million yuan.

[0085] The beneficial effects of the utility model are:

[0086] This device includes the recovery, washing, transportation, separation, adsorption, analysis, and reuse of replacement waste gas. It can set up existing automatic control programs, DCS control interlocking, alarm, automatic nitrogen filling and emptying, and online monitoring equipment to ensure the safe and stable operation of the device, solve the replacement waste gas generated during the unloading process of the wet acetylene generator, break through the environmental protection problem in safe production, and save production costs. Achieve zero emission of organic gas and achieve the purpose of reducing production costs and saving energy and reducing consumption.

[0087] In the description of the present invention, it should be understood that the terms "center", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "inside", "outside", "peripheral", "circumferential" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0088] In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0089] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0090] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for separating and recovering acetylene gas and nitrogen in the process of producing acetylene by calcium carbide method, characterized in that: The invention comprises an exhaust gas pipeline (1), a washing tower group, a water ring vacuum pump (12), a buffer gas cabinet (13), a booster (14), a demister (15) and a pressure swing adsorption device (16) which are sequentially connected through pipelines, wherein the purified gas outlet of the pressure swing adsorption device (16) is connected to the inlet of a nitrogen tank (17) through a pipeline, the outlet of the nitrogen tank (17) is connected to the exhaust gas pipeline (1), and the recovered gas outlet of the pressure swing adsorption device (16) is connected to an acetylene gas recovery pipeline (24).

2. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to claim 1, characterized in that: The washing tower group comprises a first washing tower (10) and a second washing tower (11), the inlet of the first washing tower (10) being connected to the exhaust gas pipeline (1), the outlet of the first washing tower (10) being connected to the inlet of the second washing tower (11) through a pipeline, and the outlet of the second washing tower (11) being connected to the water ring vacuum pump (12).

3. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to claim 2, characterized in that: The outlet of the nitrogen tank (17) is connected to the exhaust gas pipeline (1) via a first displacement pipeline (25). A nitrogen charging valve (6) is provided on the first displacement pipeline (25). The first displacement pipeline (25) is also connected to one end of a second displacement pipeline (26), one end of a third displacement pipeline (27) and a surplus nitrogen pipeline (23). The other end of the second displacement pipeline (26) is connected to a pipeline between the outlet of the first washing tower (10) and the inlet of the second washing tower (11). The other end of the third displacement pipeline (27) is connected to a pipeline between the water ring vacuum pump (12) and the buffer gas cabinet (13).

4. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to claim 2, characterized in that: The first washing tower (10) is also provided with a first circulation pipeline, the two ends of which are respectively connected to the top and the bottom of the first washing tower (10), the first circulation pipeline is provided with a first circulation pump (19), and the first circulation pipeline is also connected to a wastewater pipeline (22). The second washing tower (11) is also provided with a second circulation pipeline, the two ends of which are respectively connected to the top and the bottom of the second washing tower (11), the second circulation pipeline is provided with a second circulation pump (18), and the second circulation pipeline is also connected to the top of the first washing tower (10).

5. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to claim 2, characterized in that: The invention also comprises a first reflux pipeline (28), one end of which is connected to the pipeline between the outlet of the second washing tower (11) and the water ring vacuum pump (12), and the other end of which is connected to the pipeline between the water ring vacuum pump (12) and the buffer gas tank (13). The first reflux pipeline (28) is provided with a first reflux regulating valve (2), and the pipeline between the water ring vacuum pump (12) and the buffer gas tank (13) is provided with an oxygen content detection meter (3) and a shut-off valve (4).

6. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to claim 1, characterized in that: It also includes a second return pipe (29), one end of which is connected to the pipe between the buffer gas tank (13) and the booster (14), and the other end of which is connected to the pipe between the booster (14) and the demister (15), and a second return regulating valve (9) is provided on the second return pipe (29).

7. The acetylene gas and nitrogen separation and recovery system in the production of acetylene by calcium carbide process according to any one of claims 1 to 6, characterized in that: A plurality of liquid level gauges (8) are arranged at intervals on the top of the upper cabinet of the buffer gas cabinet (13).

8. The system for separating and recovering acetylene gas and nitrogen in the process of producing acetylene by the calcium carbide process according to any one of claims 1 to 6, characterized in that: The pipeline between the water ring vacuum pump (12) and the buffer gas tank (13) is also connected to an exhaust pipeline, and the exhaust pipeline is provided with an exhaust valve (5).

9. The system for separating and recovering acetylene gas and nitrogen in the process of producing acetylene by the calcium carbide process according to any one of claims 1 to 6, characterized in that: A sewage discharge pipe (30) is provided at the bottom of the demister (15).

10. The acetylene gas and nitrogen separation and recovery system in the acetylene production process by the calcium carbide process according to any one of claims 1 to 6, characterized in that: The exhaust gas pipeline (1) is provided with a pressure gauge.

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