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

Abstract

The utility model relates to a system 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 scrubber, a condenser II and a vacuum compressor which are connected in sequence. The 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 utility model is short in process route, less in equipment investment, energy-saving and environment-friendly, and less in comprehensive discharge of waste gas and waste water, and can be widely applied to a process for producing BDO by an alkyne-aldehyde method.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of chemical gas treatment, and particularly relates to a system for purifying and recovering acetylene from 1,4-butanediol production. BACKGROUND

[0002] 1,4-butanediol, abbreviated as BDO, is one of the methanol series product chains and is an important basic organic chemical and fine chemical raw material. Its main derivatives mainly include polybutylene terephthalate, polyurethane resin, spandex, gamma-butyrolactone, N-methyl pyrrolidone, etc. The derivatives of BDO are fine chemical products with high added value and are widely used in solvents, medicines, cosmetics, plasticizers, curing agents, pesticides, herbicides, foam artificial leather, fibers and engineering plastics, etc. The production technologies of 1,4-butanediol mainly include Reppe method, butadiene acetic acid method, epoxy propane method and succinic anhydride method, etc. The Reppe method is also called alkyne aldehyde method, which first reacts acetylene and formaldehyde under the action of copper bismuth catalyst to produce crude 1,4-butyne diol, and then adds hydrogen under the catalysis of skeletal nickel to obtain 1,4-butanediol after purifying and refining the crude 1,4-butyne diol.

[0003] The alkylation reaction in the BDO production technology route of the alkyne aldehyde method is a circulating reaction. The unreacted acetylene gas in the alkylation reactor circulates in the system, but as the reaction proceeds, the impurity gases and organic matters such as formaldehyde and methanol in the circulating acetylene gas will accumulate more and more. Therefore, in order to improve the efficiency of the alkylation reaction, the impurity gases affecting the reaction efficiency will be vented together with part of the acetylene gas to the acetylene torch for combustion, which wastes acetylene gas. At the same time, in order to eliminate the black smoke generated by the combustion of acetylene gas, steam needs to be supplied to the acetylene torch, and in order to ensure that the acetylene torch does not go out, the consumption of natural gas or hydrogen needs to be increased.

[0004] Chinese patent CN217829485U proposes a device for purifying and recovering acetylene from BDO exhaust gas. The device recovers acetylene in BDO exhaust gas by using a pressure swing adsorption system. Two or more sets of PSA systems can be set according to different requirements of downstream sections for acetylene concentration, but the number of equipment is large, the occupied area is large, and the cost is high.

[0005] Chinese patent CN113694698A discloses an acetylene tail gas recovery device for BDO production, which includes an acetylene tail gas that is washed by a washing tower, enters a tail gas compressor after being pressurized, and then enters an absorption tower after being dehydrated by a dehydrating system. The tail gas after low-temperature methanol absorption is sent to an acetylene torch, and the rich liquid is regenerated in a regeneration tower and returned to the absorption tower for recycling. The recovered acetylene is obtained at the top of the tower. The disadvantage of the invention is that it cannot remove unknown aldehyde and alcohol that may be produced in the alkylation reaction, so the purity of acetylene cannot be guaranteed.

[0006] The utility model discloses a device for purifying and recycling acetylene from BDO purge gas, which comprises, in sequence, an alkali washing tower, a water washing tower, a gas-liquid separator, a purification tower and an outlet air backfire preventer.

[0007] In the basic chemical industry, most enterprises have realized the "chlor-alkali-coal-electricity" integrated circular economy mode. Calcium carbide reacts with water to produce acetylene, which can be used in the chlor-alkali industry to produce polyvinyl chloride and can be used in the coal chemical industry as a raw material for producing BDO. Therefore, in order to perfect the circular economy industry chain, it is necessary to invent a system for purifying and recycling acetylene from 1,4-butanediol production, so that the recycled acetylene can be used for both BDO production and polyvinyl chloride production. SUMMARY

[0008] Based on the problems existing in the prior art, the purpose of the utility model is to provide a system for purifying and recycling acetylene from 1,4-butanediol production.

[0009] The purpose of the utility model is achieved by the following technical scheme: a system for purifying and recycling acetylene from 1,4-butanediol production, which comprises, in sequence, 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, an atmospheric degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II and a vacuum compressor.

[0010] Further, the washing tower is connected to a washing liquid circulating pump at the bottom, which provides power for the circulation of washing liquid in the washing tower.

[0011] Further, a solvent cooler, a gas-liquid separator and a circulating gas compressor are sequentially connected to the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric degassing tower. Because the temperature of the upper part of the vacuum degassing tower is high and the pressure is low, the acetylene gas desorbed from the top of the vacuum degassing tower carries part of water vapor and solvent vapor. In order to recover this part of solvent, a solvent cooler and a gas-liquid separator are provided before the circulating gas compressor to cool and separate the water vapor and solvent vapor carried by the acetylene gas desorbed from the top of the vacuum degassing tower. Then, the acetylene gas desorbed from the top of the vacuum degassing tower is sent to the atmospheric degassing tower and, together with the acetylene gas desorbed from the atmospheric degassing tower, is sent to the acetylene desorption tower.

[0012] Further, the bottom of the gas-liquid separator is connected with the top of the solvent recovery tank through a pipeline, and the acetylene gas extracted from the top of the vacuum degassing tower by the circulating gas compressor is recovered by the solvent separated from the gas-liquid separator after passing through the solvent cooler.

[0013] Further, the top of the solvent recovery tank is also connected with the condenser I and the bottom of the water washing tower through pipelines respectively, and the solvent after condensation after the acetylene gas is resolved is recovered; the bottom of the solvent recovery tank is connected with the inlet of the solvent recovery pump, and the outlet of the solvent recovery pump is connected with the outlet of the carrier gas solvent pump II, so that the recovered solvent is pressurized for secondary use.

[0014] Further, the bottom of the vacuum degassing tower is also connected with the inlet of the solvent circulating pump through a pipeline, and the outlet of the solvent circulating pump is connected with the upper part of the fresh solvent storage tank through pipelines respectively, and the pipeline connecting the solvent circulating pump with the fresh solvent storage tank is also connected with the solvent heat exchanger I, the solvent heat exchanger II and the solvent heat exchanger III in sequence, so that the solvent in the vacuum degassing tower after resolving acetylene gas and the solvent from the outlet of the carrier gas solvent pump II are exchanged in the solvent heat exchanger I, and then cooled in the solvent heat exchanger II and the solvent heat exchanger III, and then returned to the fresh solvent storage tank; the solvent heater is also connected with the middle part of the vacuum degassing tower, so as to heat the circulating solvent in the vacuum degassing tower to facilitate better resolution of acetylene gas.

[0015] Further, the solvent heater is connected with the top of the condensate tank, and the top of the condensate tank is also connected with the condenser II.

[0016] Further, the bottom of the condensate tank is connected with the inlet of the condensate pump, and the outlet of the condensate pump is connected with the upper part of the water washing tower, the acetylene resolution tower and the acetylene absorption tower through pipelines respectively, so as to further wash the solvent carried out of the system by the water vapor and acetylene gas, and ensure that the solvent is not taken out of the system.

[0017] Further, the bottom of the fresh solvent storage tank is connected with the inlet of the fresh solvent pump, and the outlet of the fresh solvent pump is connected with the middle part of the acetylene absorption tower, so as to absorb most of the acetylene gas in the acetylene purge gas in the production of 1,4-butanediol by using fresh solvent.

[0018] The utility model discloses a sodium hydroxide solution is washed and is absorbed to carbon dioxide, methanol and formaldehyde in acetylene relaxation gas, uses N-methyl pyrrolidone as absorption solvent, and the tail gas containing acetylene is absorbed and is resolved, thereby reaches the purpose that acetylene gas concentration promotes, uses negative pressure removal method to remove acetylene and moisture in solvent N-methyl pyrrolidone, thereby reaches the purpose that solvent regenerates, recycling uses, the utility model discloses process route is short, and equipment investment is little, and the layout is compact, and energy -conserving environmental protection, and acetylene recovery rate is high, and N-methyl pyrrolidone absorption efficiency is high, and in the production operation period loss is less, greatly reduces production cost, and the acetylene product gas after purification and recovery can be used as raw material for coal chemical industry production BDO, and can be used as the raw material for the production of vinyl chloride in chlor-alkali industry. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the flow diagram of the utility model.

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

[0021] Refer to the drawings Figure 1 The utility model discloses a system for purifying and recovering acetylene from 1,4-butanediol production, which comprises, in sequence, a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene resolution tower, a carrier gas solvent pump II, a solvent heat exchanger I, an atmospheric degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II, and a vacuum compressor.

[0022] Another embodiment differs in that the washing tower is connected to a washing liquid circulating pump at the bottom, and acetylene relaxation gas from 1-10 kPa in 1,4-butanediol production outside the boundary zone enters the lower part of the washing tower and is in countercurrent contact with 2-5 (wt)% sodium hydroxide solution entering the middle part of the washing tower to remove carbon dioxide, methanol, formaldehyde and other impurities in the acetylene relaxation gas, and the sodium hydroxide solution is circulated by the washing liquid circulating pump from the bottom of the washing tower to the upper part of the washing tower, and the acetylene relaxation gas flows out from the top of the washing tower and enters the acetylene booster.

[0023] Another embodiment differs in that the acetylene booster pressurizes the acetylene purge gas from the top of the washing tower to 0.1-0.13 MPa and then enters the lower part of the acetylene absorption tower, where it is countercurrently contacted with the N-methyl-pyrrolidone solution from the fresh solvent tank entering the upper part of the acetylene absorption tower, the acetylene and a small amount of nitrogen in the acetylene purge gas being absorbed by the N-methyl-pyrrolidone solution, the insoluble components being removed as tail gas from the top of the acetylene absorption tower, washed with condensed water from the condensed water tank to remove entrained solvent, and then incinerated, the carrier gas solvent being transported from the bottom of the acetylene absorption tower to the upper part of the acetylene stripping tower by carrier gas solvent pump I, part of the acetylene gas being stripped from the top of the acetylene stripping tower to the acetylene gas main after the pressure of the carrier gas solvent is reduced, and the remaining unstripped acetylene gas being carried by the solvent into the atmospheric degassing tower after being warmed by the solvent heat exchanger I, part of the acetylene gas being stripped in the atmospheric degassing tower and being sent from the top of the atmospheric degassing tower to the lower part of the acetylene stripping tower, and the acetylene gas not stripped in the atmospheric degassing tower entering the vacuum degassing tower with the carrier gas solvent.

[0024] Another embodiment differs in that a solvent cooler, a gas-liquid separator, and a circulating gas compressor are sequentially connected to the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric degassing tower, the acetylene gas stripped from the top of the vacuum degassing tower carrying part of the water vapor and solvent vapor due to the high temperature and low pressure in the upper part of the vacuum degassing tower, and in order to recover the solvent, a solvent cooler and a gas-liquid separator are provided before the circulating gas compressor to cool and separate the water vapor and solvent vapor carried by the acetylene gas stripped from the top of the vacuum degassing tower, and then the acetylene gas stripped from the top of the vacuum degassing tower is sent to the atmospheric degassing tower and then to the acetylene stripping tower together with the acetylene gas stripped from the atmospheric degassing tower.

[0025] Another embodiment differs in that the pressure of the acetylene gas stripped from the top of the acetylene stripping tower is 18-23 kPa.

[0026] Another embodiment differs in that the bottom of the gas-liquid separator is connected to the top of the solvent recovery tank by a pipeline to recover the solvent separated from the acetylene gas extracted from the top of the vacuum degassing tower by the circulating gas compressor after passing through the solvent cooler and the gas-liquid separator.

[0027] Another embodiment differs in that the top of the solvent recovery tank is also connected to condenser I and the bottom of the water washing tower by pipelines to recover the solvent after condensation after the acetylene gas is stripped, the bottom of the solvent 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 carrier gas solvent pump II to pressurize the recovered solvent for secondary use.

[0028] Another embodiment is different in that the bottom of the vacuum degassing tower is also connected with the inlet of the solvent circulating pump through a pipeline, the outlet of the solvent circulating pump is connected with the upper part of the fresh solvent tank and the solvent heater through pipelines respectively, and the pipeline connecting the solvent circulating pump and the fresh solvent tank is also connected with the solvent heat exchanger I, the solvent heat exchanger II and the solvent heat exchanger III in sequence, the solvent in the vacuum degassing tower after the resolution of acetylene gas is exchanged heat with the solvent at the outlet of the carrier gas solvent pump II in the solvent heat exchanger I, and then is cooled in the solvent heat exchanger II and the solvent heat exchanger III and returned to the fresh solvent tank.

[0029] Another embodiment is different in that the solvent heater is connected with the top of the condensate tank, and the top of the condensate tank is also connected with the condenser II.

[0030] Another embodiment is different in that the bottom of the condensate tank is connected with the inlet of the condensate pump, and the outlet of the condensate pump is connected with the upper part of the water washing tower, the acetylene resolution tower and the acetylene absorption tower through pipelines respectively, so that the solvent carried in the water vapor and the acetylene gas out of the system is further washed by using the condensate water, and the solvent is ensured not to be taken out of the system.

[0031] Another embodiment is different in that the bottom of the fresh solvent tank is connected with the inlet of the fresh solvent pump, and the outlet of the fresh solvent pump is connected with the middle part of the acetylene absorption tower, so that most of the acetylene gas in the acetylene release gas in the production of 1,4-butanediol is absorbed by using the fresh solvent.

[0032] Another embodiment is different in that the temperature of the carrier gas solvent after being exchanged heat in the solvent heat exchanger I is 65-75℃.

[0033] Another embodiment is different in that the temperature of the solvent after being heated by the solvent heater and sent to the vacuum degassing tower is 105-115℃.

[0034] Another embodiment is different in that the cooling medium of the solvent heat exchanger II is circulating water with a temperature of 30-40℃.

[0035] Another embodiment is different in that the cooling medium of the solvent heat exchanger III is refrigerated water with a temperature of 3-6℃.

[0036] Another embodiment is different in that the content of acetylene in the acetylene gas out of the top of the acetylene resolution tower is ≥98(wt)%.

[0037] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A system for purifying and recovering acetylene from the production of 1,4-butanediol, characterized by: The system comprises a washing tower, an acetylene booster, an acetylene absorption tower, a carrier gas solvent pump I, an acetylene resolution tower, a carrier gas solvent pump II, a solvent heat exchanger I, an atmospheric degassing tower, a vacuum degassing tower, a condenser I, a water washing tower, a condenser II and a vacuum compressor connected in sequence.

2. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 1, characterized by: The bottom of the washing tower is connected with a washing liquid circulating pump.

3. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 1, characterized by: A solvent cooler, a gas-liquid separator and a circulating gas compressor are connected in sequence on the pipeline between the upper part of the vacuum degassing tower and the lower part of the atmospheric degassing tower.

4. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 3, characterized by: The bottom of the gas-liquid separator is connected with the top of a solvent recovery tank through a pipeline.

5. A system for purifying and recovering acetylene from 1,4-butanediol production according to claim 4, characterized in that: The top of the solvent recovery tank is also connected with the condenser I and the bottom of the water washing tower through pipelines respectively, the bottom of the solvent recovery tank is connected with the inlet of a solvent recovery pump, and the outlet of the solvent recovery pump is connected with the outlet of the carrier gas solvent pump II.

6. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 1, characterized by: The bottom of the vacuum degassing tower is also connected with the inlet of a solvent circulating pump through a pipeline, the outlet of the solvent circulating pump is connected with the upper part of a fresh solvent storage tank through pipelines respectively, and a solvent heat exchanger I, a solvent heat exchanger II and a solvent heat exchanger III are connected in sequence on the pipeline between the solvent circulating pump and the fresh solvent storage tank; the solvent heater is also connected with the middle part of the vacuum degassing tower.

7. A system for purifying and recovering acetylene from 1,4-butanediol production according to claim 6, characterized in that: The bottom of the fresh solvent storage tank is connected with the inlet of a fresh solvent pump, and the outlet of the fresh solvent pump is connected with the middle part of the acetylene absorption tower.

8. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 6, characterized by: The solvent heater is connected with the top of a condensate tank, and the top of the condensate tank is also connected with the condenser II.

9. The system for purifying and recovering acetylene from 1,4-butanediol according to claim 8, characterized by: The bottom of the condensate tank is connected with the inlet of a condensate pump, and the outlet of the condensate pump is connected with the water washing tower, the acetylene resolution tower and the upper part of the acetylene absorption tower through pipelines respectively.

Images