Process for purifying and recovering acetylene from production of 1, 4-butanediol

Abstract

The invention relates to a process for purifying and recovering acetylene from 1, 4-butanediol production, which comprises a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene desorption tower, a carrier gas solvent pump II, a solvent heat exchanger I, a normal pressure degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II and a vacuum compressor which are connected in sequence. The invention discloses a system for purifying and recovering acetylene in 1, 4-butanediol production. According to the method, acetylene in purge gas generated in the ethynylation reaction process of a 1, 4-butanediol production device is purified and recycled by adopting a process of absorbing acetylene by adopting an N-methyl-pyrrolidone solution, and acetylene and water in an absorption solvent N-methyl-pyrrolidone are removed by adopting a negative pressure removal method; therefore, the purposes of solvent regeneration and cyclic utilization are achieved, and the production cost is greatly reduced. The system disclosed by the invention is short in process route, low in equipment investment, energy-saving and environment-friendly, and low in comprehensive discharge of waste gas and wastewater, and can be widely applied to a process for producing BDO by an alkyne-aldehyde method.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical gas processing, and specifically relates to a process for purifying and recovering acetylene from the production of 1,4-butanediol. Background Art

[0002] 1,4-Butanediol, referred to as BDO, is one of the methanol product chains and an important basic organic chemical and fine chemical raw material. Its main derivatives include polybutylene terephthalate, polyurethane resin, spandex, γ-butyrolactone, N-methylpyrrolidone, etc. BDO derivatives are fine chemical products with high added value and are widely used in solvents, medicines, cosmetics, plasticizers, curing agents, pesticides, herbicides, foamed leather, fibers and engineering plastics. The main production technologies of 1,4-butanediol include the Reppe method, butadiene acetate method, propylene oxide method and maleic anhydride method. The Reppe method is also called the acetylene aldehyde method. First, acetylene and formaldehyde are reacted under the action of copper bismuth catalyst to produce crude 1,4-butynediol. Then, the crude 1,4-butynediol is purified and refined, and then reacted with hydrogen under the action of skeleton nickel catalyst to obtain 1,4-butanediol.

[0003] The acetylation reaction in the acetylenic aldehyde process for producing BDO is a cyclic reaction. The unreacted acetylene gas in the acetylation reactor circulates in the system. However, as the reaction proceeds, the impurity gas and organic substances such as formaldehyde and methanol in the circulating acetylene gas will accumulate more and more. Therefore, in order to improve the efficiency of the acetylation reaction, the impurity gas that affects the reaction efficiency is usually vented to the acetylene torch together with part of the acetylene gas for combustion, which wastes the acetylene gas. At the same time, in order to eliminate the black smoke generated by the combustion of acetylene gas, it is necessary to transport steam to the acetylene torch, and in order to ensure that the acetylene torch does not go out, it is necessary to increase the consumption of natural gas or hydrogen.

[0004] Chinese patent CN217829485U proposes a device for purifying and recovering acetylene from BDO exhaust gas. The device uses a pressure swing adsorption system to recover acetylene from BDO exhaust gas. Two or more PSA systems can be set according to the different requirements of downstream sections for acetylene concentration. However, the number of equipment is large, the floor space is large, and the cost is high.

[0005] Chinese patent CN113694698A discloses an acetylene tail gas recovery device for BDO production, including acetylene tail gas washing in a washing tower and then entering a tail gas compressor, passing through a deliquescence system after pressurization, and then entering an absorption tower after removing water and other small droplets, and then the tail gas after being absorbed by low-temperature methanol is sent to an acetylene torch, and the rich liquid enters a regeneration tower for regeneration, and the regenerated liquid at the bottom of the tower is returned to the absorption tower for recycling, and the acetylene is recovered at the top of the tower. The disadvantage of this invention is that it cannot remove unknown aldehydes and alcohols that may be produced in the acetylation reaction, so the purity of acetylene cannot be guaranteed.

[0006] Chinese patent CN220090985U proposes a device for purifying and recovering acetylene from BDO purge gas, the device comprising an alkali washing tower, a water washing tower, a gas-liquid separator, a purification tower, and an outlet flashback arrester connected in sequence. The utility model adopts the method of "alkali washing + water washing + adsorption" to purify and recover the acetylene in the purge gas generated during the acetylation reaction of the BDO production device. Although the configuration is simple, the footprint is small, and the operation is convenient, the device adopts a physical method to recover acetylene, and the trace organic impurities in the purge gas cannot be completely processed, resulting in the recovered acetylene gas cannot be used for polyvinyl chloride production; in addition, the adsorbent needs to be replaced regularly, which is costly.

[0007] In the basic chemical industry, most companies have realized the "chlor-alkali coal-electricity" integrated circular economy model. Calcium carbide reacts with water to produce acetylene, which can be used in the chlor-alkali industry to produce polyvinyl chloride and in the coal chemical industry as a raw material for producing BDO. Therefore, in order to improve the circular economy industry chain, it is necessary to invent a process for purifying and recovering acetylene from 1,4-butanediol production, so that the recovered acetylene can be used for both BDO production and polyvinyl chloride production. Summary of the invention

[0008] Based on the problems existing in the prior art, the object of the present invention is to provide a process for purifying and recovering acetylene from the production of 1,4-butanediol.

[0009] The object of the present invention is achieved through the following technical scheme: a process for purifying and recovering acetylene from the production of 1,4-butanediol is achieved by a system for purifying and recovering acetylene from the production of 1,4-butanediol, the system comprising a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene analysis tower, a carrier gas solvent pump II, a solvent heat exchanger I, a normal pressure degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II, and a vacuum compressor connected in sequence, the washing tower bottom is connected to a washing liquid circulation pump, the pipeline between the upper part of the vacuum degassing tower and the lower part of the normal pressure degassing tower is also connected in sequence to a solvent cooler, a gas-liquid separator, and a circulating gas compressor, the bottom of the gas-liquid separator is connected to the top of a solvent recovery tank through a pipeline, the top of the solvent recovery tank is also connected to the bottom of the condenser I and the water washing tower through pipelines, and the bottom of the solvent recovery tank is connected to the solvent The solvent recovery pump inlet is connected, the solvent recovery pump outlet is connected to the carrier gas solvent pump II outlet, the bottom of the vacuum degassing tower is also connected to the solvent circulation pump inlet through a pipeline, the solvent circulation pump outlet is respectively connected to the solvent heater and the upper part of the fresh solvent storage tank through pipelines, and the solvent circulation pump is connected to the fresh solvent storage tank through the pipeline. Solvent heat exchanger I, solvent heat exchanger II, and solvent heat exchanger III are also connected in series in sequence; the solvent heater is also connected to the middle part of the vacuum degassing tower, the bottom of the fresh solvent storage tank is connected to the fresh solvent pump inlet, the fresh solvent pump outlet is connected to the middle part of the acetylene absorption tower, the solvent heater is connected to the top of the condensed water tank, the top of the condensed water tank is also connected to condenser II, the bottom of the condensed water tank is connected to the condensed water pump inlet, and the condensed water pump outlet is respectively connected to the water washing tower, the acetylene analysis tower, and the upper part of the acetylene absorption tower through pipelines.

[0010] The process for purifying and recovering acetylene from the production of 1,4-butanediol comprises the following steps: (1) Raw gas washing: The acetylene purge gas with a pressure of 1-10 kPa from the 1,4-butanediol production outside the boundary area enters from the bottom of the washing tower and contacts with the solvent I entering from the middle of the washing tower in reverse order to remove impurities such as carbon dioxide, methanol and formaldehyde from the acetylene purge gas. The solvent I is sent from the bottom of the washing tower to the top of the washing tower through the washing liquid circulation pump for recycling. The acetylene purge gas flows out from the top of the washing tower and enters the acetylene booster; (2) Acetylene gas compression: The acetylene booster pressurizes the acetylene purge gas flowing out of the top of the scrubber to 0.1-0.13 MPa and then enters the lower middle part of the acetylene absorption tower; (3) Acetylene gas concentration: The pressurized acetylene gas enters the lower middle part of the acetylene absorber and contacts in reverse with the solvent II from the fresh solvent storage tank entering the upper middle part of the acetylene absorber. The acetylene and a small amount of nitrogen in the acetylene purge gas are absorbed by the solvent II. The insoluble components are washed with condensed water from the condensed water tank at the top of the acetylene absorber as tail gas to remove the entrained solvent and then incinerated. The carrier gas solvent is transported from the bottom of the acetylene absorber to the upper part of the acetylene desorption tower through the carrier gas solvent pump I. After the pressure is reduced, part of the carrier gas solvent is discharged. Acetylene gas is decomposed from the top of the acetylene decomposition tower and then washed with water to remove the solvent II colloid and then sent to the acetylene gas main pipe. The remaining undecomposed acetylene gas is carried by the solvent and heated by the solvent heat exchanger I and then brought into the atmospheric pressure degassing tower. Part of the acetylene gas is decomposed in the atmospheric pressure degassing tower and sent from the top of the atmospheric pressure degassing tower to the middle and lower part of the acetylene decomposition tower; the undecomposed acetylene gas in the atmospheric pressure degassing tower enters the vacuum degassing tower with the carrier gas solvent; the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric pressure degassing tower is also connected in sequence with the solvent cooling unit. The acetylene gas analyzed from the top of the vacuum degassing tower is cooled and separated by a cooler, a gas-liquid separator, and a circulating gas compressor. The water vapor and solvent vapor carried by the acetylene gas analyzed from the top of the vacuum degassing tower are cooled and separated, and then the acetylene gas analyzed from the top of the vacuum degassing tower is sent to the atmospheric pressure degassing tower, and sent to the acetylene analysis tower together with the acetylene gas analyzed from the atmospheric pressure degassing tower, and then enters the acetylene gas main pipe; a large amount of water vapor gathers in the middle of the vacuum degassing tower. If this part of water vapor is not removed, the water content of the solvent II circulation system will increase. Therefore, this part of water vapor is extracted from the middle of the vacuum degassing tower. This part of water vapor carries a large amount of solvent II vapor, and a large amount of solvent II vapor is condensed by condenser I. In order to ensure that the solvent II in the water vapor is not taken out of the system, a water washing tower is set after condenser I, and the solvent II in the water vapor is completely washed and recovered with condensed water and sent to the solvent recovery tank. The remaining water vapor needs to be condensed by condenser II before entering the vacuum compressor due to its large volume. The non-condensable gas is compressed to 2-4kPa by the vacuum compressor and then sent out of the system; (4) Solvent circulation: Solvent II from the fresh solvent storage tank and the mixed gas from the acetylene booster are countercurrently contacted in the acetylene absorption tower. Solvent II absorbs the acetylene in the mixed gas and enters the acetylene absorption tower kettle. It is then sent to the upper middle part of the acetylene desorption tower by the carrier gas solvent pump I. Most of the acetylene gas is desorbed from solvent II, and a small amount of acetylene gas still exists in solvent II. This part of solvent II is transported by the carrier gas solvent pump II, and after heat exchange with the high-temperature solvent from the vacuum degassing tower by the solvent heat exchanger I, it enters the atmospheric pressure degassing tower; some of the acetylene gas in the carrier gas solvent is discharged from the degassing tower. Due to the increase in temperature, the solvent II after decomposition still contains a small amount of acetylene gas, which enters the top of the vacuum degassing tower through static pressure. After entering the vacuum degassing tower, the pressure of solvent II drops sharply, and all the acetylene gas in solvent II is decomposed; solvent II enters the bottom of the vacuum degassing tower, and after the solvent circulation pump increases the pressure, a part of it is circulated through the solvent heater to heat the solvent II in the vacuum degassing tower, and the other part enters the solvent heat exchanger I and exchanges heat with the carrier gas solvent at the outlet of the carrier gas solvent pump II, and then cools down through the solvent heat exchanger II and the solvent heat exchanger III before entering the fresh solvent storage tank. The carrier gas solvent at the outlet of the carrier gas solvent pump II has a high water content and cannot be directly added to the vacuum system composed of the atmospheric pressure degassing tower and the vacuum degassing tower. Therefore, a mixed solvent from the solvent recovery tank is added to the pipeline entering the solvent heat exchanger I.

[0011] Furthermore, the solvent I is a 2-5 (wt)% sodium hydroxide solution.

[0012] Furthermore, the solvent II is a 99.0-99.9 (wt)% N-methyl-pyrrolidone solution.

[0013] Furthermore, the temperature of the carrier gas solvent at the outlet of the carrier gas solvent pump II after heat exchange in the solvent heat exchanger I is 65-75°C.

[0014] Furthermore, the temperature of the solvent II in the bottom of the vacuum degassing tower is 105-115°C.

[0015] Furthermore, the cooling medium of the solvent heat exchanger II is circulating water at 30-40°C.

[0016] Furthermore, the cooling medium of the solvent heat exchanger III is chilled water at 3-6°C.

[0017] Furthermore, the acetylene content in the acetylene gas exiting the top of the acetylene analysis tower is ≥98 (wt)%.

[0018] The present invention uses sodium hydroxide solution to wash and absorb carbon dioxide, methanol and formaldehyde in acetylene purge gas; uses N-methylpyrrolidone as an absorption solvent to absorb and analyze tail gas containing acetylene, thereby achieving the purpose of increasing the concentration of acetylene gas; and uses a negative pressure removal method to remove acetylene and water in the solvent N-methylpyrrolidone, thereby achieving the purpose of solvent regeneration and recycling. The present invention has a short process route, low equipment investment, compact layout, energy saving and environmental protection, high acetylene gas recovery rate, high N-methylpyrrolidone absorption efficiency, and less loss during production and operation, which greatly reduces production costs. The purified and recovered acetylene product gas can be used as a raw material for the production of BDO in the coal chemical industry, and can also be used in the chlor-alkali industry as a raw material for the production of vinyl chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a simplified flow chart of the present invention.

[0020] Figure 1 Among them, 1 is a washing tower, 2 is a washing liquid circulation pump, 3 is an acetylene booster, 4 is an acetylene absorption tower, 5 is a carrier gas solvent pump I, 6 is an acetylene analysis tower, 7 is a carrier gas solvent pump II, 8 is a solvent heat exchanger I, 9 is a solvent heat exchanger II, 10 is a solvent heat exchanger III, 11 is a circulating gas compressor, 12 is a solvent cooler, 13 is a gas-liquid separator, 14 is a fresh solvent pump, 15 is a normal pressure degassing tower, 16 is a vacuum degassing tower, 17 is a fresh solvent storage tank, 18 is a solvent circulation pump, 19 is a solvent heater, 20 is a condenser I, 21 is a water washing tower, 22 is a condenser II, 23 is a vacuum compressor, 24 is a solvent recovery tank, 25 is a solvent recovery pump, 26 is a condensate tank, and 27 is a condensate pump. DETAILED DESCRIPTION

[0021] Refer to the attached Figure 1The embodiment of the present invention provides a process for purifying and recovering acetylene from the production of 1,4-butanediol. The process for purifying and recovering acetylene from the production of 1,4-butanediol is realized by a system for purifying and recovering acetylene from the production of 1,4-butanediol. The system comprises a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene analysis tower, a carrier gas solvent pump II, a solvent heat exchanger I, a normal pressure degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II, and a vacuum compressor connected in sequence. The bottom of the washing tower is connected to a washing liquid circulation pump. The pipeline between the upper part of the vacuum degassing tower and the lower part of the normal pressure degassing tower is also connected in sequence to a solvent cooler, a gas-liquid separator, and a circulating gas compressor. The bottom of the gas-liquid separator is connected to the top of a solvent recovery tank through a pipeline. The top of the solvent recovery tank is also connected to the bottom of the condenser I and the water washing tower through pipelines. The bottom of the recovery tank is connected to the inlet of the solvent recovery pump, and the outlet of the solvent recovery pump is connected to the outlet of the carrier gas solvent pump II. The bottom of the vacuum degassing tower is also connected to the inlet of the solvent circulation pump through a pipeline, and the outlet of the solvent circulation pump is respectively connected to the solvent heater and the upper part of the fresh solvent storage tank through pipelines. The pipeline connecting the solvent circulation pump and the fresh solvent storage tank is also connected in series with solvent heat exchanger I, solvent heat exchanger II, and solvent heat exchanger III in sequence; the solvent heater is also connected to the middle part of the vacuum degassing tower, the bottom of the fresh solvent storage tank is connected to the inlet of the fresh solvent pump, and the outlet of the fresh solvent pump is connected to the middle part of the acetylene absorption tower, the solvent heater is connected to the top of the condensed water tank, and the top of the condensed water tank is also connected to condenser II, the bottom of the condensed water tank is connected to the inlet of the condensed water pump, and the outlet of the condensed water pump is respectively connected to the water washing tower, the acetylene analysis tower, and the upper part of the acetylene absorption tower through pipelines.

[0022] The process for purifying and recovering acetylene from the production of 1,4-butanediol comprises the following steps: (1) Raw gas washing: The acetylene purge gas with a pressure of 1-10 kPa from the 1,4-butanediol production outside the boundary area enters from the bottom of the washing tower and contacts with the solvent I entering from the middle of the washing tower in reverse order to remove impurities such as carbon dioxide, methanol and formaldehyde from the acetylene purge gas. The solvent I is sent from the bottom of the washing tower to the top of the washing tower through the washing liquid circulation pump for recycling. The acetylene purge gas flows out from the top of the washing tower and enters the acetylene booster; (2) Acetylene gas compression: The acetylene booster pressurizes the acetylene purge gas flowing out of the top of the scrubber to 0.1-0.13 MPa and then enters the lower middle part of the acetylene absorption tower; (3) Acetylene gas concentration: The pressurized acetylene gas enters the lower middle part of the acetylene absorption tower and contacts in reverse with the solvent II from the fresh solvent storage tank entering the upper middle part of the acetylene absorption tower. The acetylene and a small amount of nitrogen in the acetylene purge gas are absorbed by the solvent II. The insoluble components are washed with condensed water from the condensed water tank at the top of the acetylene absorption tower as tail gas to remove the entrained solvent and then incinerated. The carrier gas solvent is transported from the bottom of the acetylene absorption tower to the upper part of the acetylene desorption tower through the carrier gas solvent pump I. After the pressure of the carrier gas solvent is reduced, part of the acetylene gas is desorbed from the top of the acetylene desorption tower to the acetylene gas main pipe. The remaining undesorbed acetylene gas is carried by the solvent and heated by the solvent heat exchanger I and brought into the atmospheric pressure degassing tower. Part of the acetylene gas is desorbed in the atmospheric pressure degassing tower and is transported from the top of the atmospheric pressure degassing tower to the lower middle part of the acetylene desorption tower. The acetylene gas analyzed by the vacuum degassing tower enters the vacuum degassing tower with the carrier gas solvent; the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric pressure degassing tower is also connected with a solvent cooler, a gas-liquid separator, and a circulating gas compressor in sequence, and the water vapor and solvent vapor carried by the acetylene gas analyzed by the top of the vacuum degassing tower are cooled and separated, and then the acetylene gas analyzed by the top of the vacuum degassing tower is sent to the atmospheric pressure degassing tower, and sent to the acetylene analysis tower together with the acetylene gas analyzed by the atmospheric pressure degassing tower, and then enters the acetylene gas main pipe; a large amount of water vapor gathers in the middle of the vacuum degassing tower, and this part of the water vapor carries a large amount of solvent II vapor. The solvent II vapor is recovered by condensation in condenser I and washing in a water washing tower and then sent to the solvent recovery tank, and the remaining water vapor enters the system after being condensed by condenser II and compressed by a vacuum compressor; (4) Solvent circulation: Solvent II from the fresh solvent storage tank and the mixed gas from the acetylene booster are countercurrently contacted in the acetylene absorption tower. Solvent II absorbs the acetylene in the mixed gas and enters the acetylene absorption tower kettle. It is then sent to the upper middle part of the acetylene desorption tower by the carrier gas solvent pump I. Most of the acetylene gas is desorbed from solvent II, and a small amount of acetylene gas still exists in solvent II. This part of solvent II is transported by the carrier gas solvent pump II, and after heat exchange with the high-temperature solvent from the vacuum degassing tower by the solvent heat exchanger I, it enters the atmospheric pressure degassing tower; some of the acetylene gas in the carrier gas solvent is discharged from the degassing tower. Due to the increase in temperature, the solvent II is decomposed. A small amount of acetylene gas is still contained in the decomposed solvent II, which enters the top of the vacuum degassing tower through static pressure. The pressure of the solvent II drops sharply after entering the vacuum degassing tower, and all the acetylene gas in the solvent II is decomposed; the solvent II enters the bottom of the vacuum degassing tower, and after the pressure is increased by the solvent circulation pump, a part of it is circulated through the solvent heater to heat the solvent II in the vacuum degassing tower, and the other part enters the solvent heat exchanger I and exchanges heat with the carrier gas solvent at the outlet of the carrier gas solvent pump II, and then enters the fresh solvent storage tank after being cooled by the solvent heat exchanger II and the solvent heat exchanger III.

[0023] The solvent I is a 2 (wt)% sodium hydroxide solution.

[0024] Another embodiment is different in that the solvent I is a 3 (wt) % sodium hydroxide solution.

[0025] Another embodiment is different in that the solvent I is a 5 (wt)% sodium hydroxide solution.

[0026] The solvent II is a 99.0 (wt)% N-methyl-pyrrolidone solution.

[0027] Another embodiment is different in that the solvent II is a 99.5 (wt) % N-methyl-pyrrolidone solution.

[0028] Another embodiment is different in that the solvent II is a 99.9 (wt) % N-methyl-pyrrolidone solution.

[0029] The temperature of the carrier gas solvent at the outlet of the carrier gas solvent pump II after heat exchange in the solvent heat exchanger I is 65°C.

[0030] Another embodiment is different in that the temperature of the carrier gas solvent at the outlet of the carrier gas solvent pump II after heat exchange in the solvent heat exchanger I is 70°C.

[0031] Another embodiment is different in that the temperature of the carrier gas solvent at the outlet of the carrier gas solvent pump II after heat exchange in the solvent heat exchanger I is 75°C.

[0032] The temperature of the solvent II in the bottom of the vacuum degassing tower is 105°C.

[0033] Another embodiment is different in that the temperature of the solvent II in the bottom of the vacuum degassing tower is 110°C.

[0034] Another embodiment is different in that the temperature of the solvent II in the bottom of the vacuum degassing tower is 115°C.

[0035] The cooling medium of the solvent heat exchanger II is circulating water at 30°C.

[0036] Another embodiment is different in that the cooling medium of the solvent heat exchanger II is circulating water at 35°C.

[0037] Another embodiment is different in that the cooling medium of the solvent heat exchanger II is circulating water at 40°C.

[0038] The cooling medium of the solvent heat exchanger III is 3°C chilled water.

[0039] Another embodiment is different in that the cooling medium of the solvent heat exchanger III is 4.5°C chilled water.

[0040] Another embodiment is different in that the cooling medium of the solvent heat exchanger III is 6°C chilled water.

[0041] The acetylene content in the acetylene gas exiting the top of the acetylene analysis tower is ≥98 (wt) %.

[0042] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for purifying and recovering acetylene from the production of 1,4-butanediol, characterized in that: The process is realized by a system for purifying and recovering acetylene from the production of 1,4-butanediol. The system comprises a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene analysis tower, a carrier gas solvent pump II, a solvent heat exchanger I, a normal pressure degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II, and a vacuum compressor, which are connected in sequence. The bottom of the washing tower is connected to a washing liquid circulation pump. The pipeline between the upper part of the vacuum degassing tower and the lower part of the normal pressure degassing tower is also connected in sequence to a solvent cooler, a gas-liquid separator, and a circulating gas compressor. The bottom of the gas-liquid separator is connected to the top of a solvent recovery tank through a pipeline. The top of the solvent recovery tank is also connected to the bottom of the condenser I and the water washing tower through pipelines respectively. The bottom of the solvent recovery tank is connected to the inlet of the solvent recovery pump. The outlet of the solvent recovery pump is connected to the outlet of the solvent recovery pump. The outlet of the carrier gas solvent pump II is connected, the bottom of the vacuum degassing tower is also connected to the inlet of the solvent circulation pump through a pipeline, the outlet of the solvent circulation pump is respectively connected to the solvent heater and the upper part of the fresh solvent storage tank through pipelines, and the pipeline connecting the solvent circulation pump and the fresh solvent storage tank is also connected in series with solvent heat exchanger I, solvent heat exchanger II, and solvent heat exchanger III in sequence; the solvent heater is also connected to the middle part of the vacuum degassing tower, the bottom of the fresh solvent storage tank is connected to the inlet of the fresh solvent pump, the outlet of the fresh solvent pump is connected to the middle part of the acetylene absorption tower, the solvent heater is connected to the top of the condensed water tank, the top of the condensed water tank is also connected to condenser II, the bottom of the condensed water tank is connected to the inlet of the condensed water pump, and the outlet of the condensed water pump is respectively connected to the water washing tower, the acetylene analysis tower, and the upper part of the acetylene absorption tower through pipelines; The process for purifying and recovering acetylene from the production of 1,4-butanediol is characterized by comprising the following steps: (1) Raw gas washing: The acetylene purge gas with a pressure of 1-10 kPa from the 1,4-butanediol production outside the boundary area enters from the bottom of the washing tower and contacts with the solvent I entering from the middle of the washing tower in reverse order to remove impurities such as carbon dioxide, methanol and formaldehyde from the acetylene purge gas. The solvent I is sent from the bottom of the washing tower to the top of the washing tower through the washing liquid circulation pump for recycling. The acetylene purge gas flows out from the top of the washing tower and enters the acetylene booster; (2) Acetylene gas compression: The acetylene booster pressurizes the acetylene purge gas flowing out of the top of the scrubber to 0.1-0.13 MPa and then enters the middle and lower part of the acetylene absorption tower; (3) Acetylene gas concentration: The pressurized acetylene gas enters the lower middle part of the acetylene absorption tower and contacts in reverse with the solvent II from the fresh solvent storage tank entering the upper middle part of the acetylene absorption tower. The acetylene and a small amount of nitrogen in the acetylene purge gas are absorbed by the solvent II. The insoluble components are washed with condensed water from the condensed water tank at the top of the acetylene absorption tower as tail gas to remove the entrained solvent and then incinerated. The carrier gas solvent is transported from the bottom of the acetylene absorption tower to the upper part of the acetylene desorption tower through the carrier gas solvent pump I. After the pressure of the carrier gas solvent is reduced, part of the acetylene gas is desorbed from the top of the acetylene desorption tower to the acetylene gas main pipe. The remaining undesorbed acetylene gas is carried by the solvent and heated by the solvent heat exchanger I and brought into the atmospheric pressure degassing tower. Part of the acetylene gas is desorbed in the atmospheric pressure degassing tower and is transported from the top of the atmospheric pressure degassing tower to the lower middle part of the acetylene desorption tower. The acetylene gas analyzed by the vacuum degassing tower enters the vacuum degassing tower with the carrier gas solvent; the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric pressure degassing tower is also connected with a solvent cooler, a gas-liquid separator, and a circulating gas compressor in sequence, and the water vapor and solvent vapor carried by the acetylene gas analyzed by the top of the vacuum degassing tower are cooled and separated, and then the acetylene gas analyzed by the top of the vacuum degassing tower is sent to the atmospheric pressure degassing tower, and sent to the acetylene analysis tower together with the acetylene gas analyzed by the atmospheric pressure degassing tower, and then enters the acetylene gas main pipe; a large amount of water vapor gathers in the middle of the vacuum degassing tower, and this part of the water vapor carries a large amount of solvent II vapor. The solvent II vapor is recovered by condensation in condenser I and washing in a water washing tower and then sent to the solvent recovery tank, and the remaining water vapor enters the system after being condensed by condenser II and compressed by a vacuum compressor; (4) Solvent circulation: Solvent II from the fresh solvent storage tank and the mixed gas from the acetylene booster are countercurrently contacted in the acetylene absorption tower. Solvent II absorbs the acetylene in the mixed gas and enters the acetylene absorption tower kettle. It is then sent to the upper middle part of the acetylene desorption tower by the carrier gas solvent pump I. Most of the acetylene gas is desorbed from solvent II, and a small amount of acetylene gas still exists in solvent II. This part of solvent II is transported by the carrier gas solvent pump II, and after heat exchange with the high-temperature solvent from the vacuum degassing tower by the solvent heat exchanger I, it enters the atmospheric pressure degassing tower; some of the acetylene gas in the carrier gas solvent is discharged from the degassing tower. Due to the increase in temperature, the solvent II is decomposed. A small amount of acetylene gas is still contained in the decomposed solvent II, which enters the top of the vacuum degassing tower through static pressure. The pressure of the solvent II drops sharply after entering the vacuum degassing tower, and all the acetylene gas in the solvent II is decomposed; the solvent II enters the bottom of the vacuum degassing tower, and after the pressure is increased by the solvent circulation pump, a part of it is circulated through the solvent heater to heat the solvent II in the vacuum degassing tower, and the other part enters the solvent heat exchanger I and exchanges heat with the carrier gas solvent at the outlet of the carrier gas solvent pump II, and then enters the fresh solvent storage tank after being cooled by the solvent heat exchanger II and the solvent heat exchanger III.

2. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: Solvent I is a 2-5 (wt)% sodium hydroxide solution.

3. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: Solvent II is a 99.0-99.9 (wt) % N-methyl-pyrrolidone solution.

4. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: The temperature of the carrier gas solvent at the outlet of the carrier gas solvent pump II after heat exchange in the solvent heat exchanger I is 65-75°C.

5. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: The temperature of the solvent II in the bottom of the vacuum degassing tower is 105-115°C.

6. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: The cooling medium of the solvent heat exchanger II is circulating water at 30-40°C.

7. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: The cooling medium of the solvent heat exchanger III is 3-6°C chilled water.

8. A process for purifying and recovering acetylene from the production of 1,4-butanediol according to claim 1, characterized in that: The acetylene content in the acetylene gas exiting the top of the acetylene analysis tower is ≥98 (wt)%.

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