1, 4-butanediol production process ethynylation reaction tail gas recovery system in alkyne aldehyde method

Abstract

The utility model discloses a 1, 4-butanediol production process ethynylation reaction tail gas recovery system in an alkyne aldehyde method, which comprises a water scrubber, a liquid ring compressor, a mechanical seal water heat exchanger, a precooler, a methanol absorption tower, a methanol heat exchanger, a tail gas desorption tower and a desorption tower medium heat exchanger. According to the utility model, the traditional ethynylation reaction emptying incineration is changed into collection of low-temperature methanol absorption, analysis and recovery, so that the acetylene gas waste is avoided, the unit consumption of calcium carbide of the device is reduced, the production cost is saved, the carbon emission pressure caused by environment-friendly burning is reduced, and the recovery rate is high. According to the acetylene gas recovery device, the emptied acetylene gas is recovered, low-temperature methanol is used for absorption, the acetylene gas is recovered, and the recovery rate is more than 90%.

Description

Technical Field

[0001] This utility model relates to the field of acetylation aldehyde process technology for 1,4-butanediol (BDO), and particularly to a system for recovering tail gas from the acetylation reaction in the acetylation aldehyde process for the production of 1,4-butanediol. Background Technology

[0002] Currently, in the acetylene-aldehyde process for producing 1,4-butanediol (BDO), acetylene gas is stirred and mixed with formaldehyde solution in an acetylene reaction reactor, where it reacts to produce BYD under the action of a copper-bismuth catalyst. Throughout the production process, to ensure the effectiveness of the acetylene reaction, the acetylene gas concentration in the reactor must be maintained above 80%. However, industrially produced acetylene contains approximately 1% nitrogen, which can reach a concentration of 20-30% after enrichment in the reaction system. To maintain the reaction efficiency, the acetylene gas must be discharged as tail gas to reduce the nitrogen content. This discharged acetylene tail gas is then sent to a flare system for combustion, resulting in significant resource waste.

[0003] Under current technology, the shortcomings of acetylene combustion following acetylene venting in acetylene reactions are:

[0004] 1. Directly sending acetylene tail gas into the flare for incineration results in a huge waste of resources and carbon emissions, which is inconsistent with the concept of green and low-carbon development.

[0005] 2. The production process is prone to high calcium carbide consumption, which increases production costs. Utility Model Content

[0006] The purpose of this invention is to overcome the deficiencies of existing technologies and provide a tail gas recovery system for the acetylation reaction in the 1,4-butanediol production process using the acetylation-aldehyde method. The main tail gas recovery system of this invention includes: a reaction venting tail gas washing tower, a tail gas compressor, a compressor sealing water heat exchanger, a methanol absorption tower precooler, a methanol absorption tower, a methanol heat exchanger, a tail gas desorption tower, and other related pumps and equipment. This invention achieves a recovery rate of over 90% for the venting tail gas from the acetylation reaction of 1,4-butanediol (BDO) using the acetylation-aldehyde method.

[0007] This utility model is achieved through the following technical solution:

[0008] A tail gas recovery system for the acetylene reaction in the 1,4-butanediol production process via the acetylene-aldehyde method includes a water washing tower, a liquid ring compressor, a mechanically sealed water heat exchanger, a precooler, a methanol absorption tower, a methanol heat exchanger, a tail gas desorption tower, and a desorption tower medium heat exchanger. The acetylene tail gas outlet of the acetylene reaction system is connected to the gas inlet of the water washing tower. The gas outlet at the top of the water washing tower is connected to the inlet of the liquid ring compressor. The mechanically sealed water outlet of the liquid ring compressor is connected to the inlet of the mechanically sealed water heat exchanger. The outlet of the mechanically sealed water heat exchanger is connected to the top inlet of the water washing tower. The gas outlet of the liquid ring compressor is connected to the gas inlet of the precooler. The gas outlet of the precooler is connected to the... The lower gas inlet of the methanol absorption tower is connected, and the bottom solution outlet of the methanol absorption tower is connected to the top solution inlet of the tail gas desorption tower. The methanol heat exchanger is equipped with a room temperature methanol inlet pipeline, a heat-exchanged methanol outlet pipeline, a low temperature methanol inlet pipeline, and a low temperature methanol outlet pipeline. The heat-exchanged methanol outlet pipeline of the methanol heat exchanger is connected to the methanol inlet at the top of the methanol absorption tower. The solution outlet of the desorption tower medium heat exchanger is connected to the bottom solution inlet of the tail gas desorption tower. The top of the tail gas desorption tower is equipped with a gas outlet, and the bottom of the tail gas desorption tower is also equipped with a methanol outlet, which is connected to the room temperature methanol inlet pipeline of the methanol heat exchanger.

[0009] A water washing liquid pump circulation and discharge device is connected to the bottom of the water washing tower.

[0010] The precooler is equipped with a precooling inlet pipeline and a precooling outlet pipeline.

[0011] The precooler is provided in two units, with one precooler in operation and the other on standby.

[0012] A pump is connected to the methanol outlet at the bottom of the tail gas desorption tower. The pump outlet is connected to the ambient temperature methanol inlet pipeline of the methanol heat exchanger, and the pump outlet is also connected to a methanol discharge pipeline.

[0013] The gas outlet at the top of the exhaust gas analysis tower is connected to a gas discharge pipeline.

[0014] The vent gas from the acetylene reaction system reactor is collected and fed into a water scrubbing tower. The gas is pressurized by a liquid ring compressor to increase the acetylene pressure in the system, facilitating methanol absorption. The liquid ring compressor's sealing water cools the compressor's mechanical seal using its own pressure. After being cooled by a mechanical seal water heat exchanger, the compressor sealing water enters the water scrubbing tower and comes into counter-current contact with the collected acetylene gas to remove impurities from the acetylene tail gas. The water is recycled, reducing the demineralized water consumed by the water scrubbing tower itself. Water is discharged promptly according to the water scrubbing tower's level to ensure system stability. The precooler uses chilled water (-7°C) as the precooling agent. The chilled water enters the precooler and exchanges heat with the pressurized acetylene gas, freezing and frosting to remove moisture from the acetylene gas. The precooler operates with one unit on and one unit on standby to avoid frost buildup on the heat exchanger, which would affect the unit's operation. The chilled water after heat exchange is returned to the pipeline system. The pressurized and dehydrated acetylene gas then enters the methanol absorption tower. The system is replenished with ambient temperature methanol, and the methanol absorption tower establishes its level. Low-temperature formaldehyde enters a methanol heat exchanger to exchange heat with room-temperature methanol (low-temperature methanol temperature -60℃). After heat exchange, the low-temperature methanol returns to the original system. The low-temperature methanol circulation only absorbs cold energy, without wasting low-pressure, low-temperature methanol, and can be repeatedly recycled. The pressure of the methanol absorption tower is controlled, and the low-temperature methanol containing dissolved acetylene is transported to the tail gas stripping tower via pressure differential. The bottom circulation of the tail gas stripping tower passes through the stripping tower medium heat exchanger to increase the temperature of the ethylene glycol at the bottom of the tower, thereby increasing the acetylene stripping rate. Based on the analysis of the methanol content and moisture in the tail gas stripping tower, methanol is added to the system to increase the methanol concentration and raise the temperature of the heat exchanger medium at the bottom of the stripping tower. Inert gases not absorbed by the low-temperature methanol are discharged to the flare system. Based on the purity of the acetylene gas recovered from the stripping tower, the inert gas venting rate of the methanol absorption tower is adjusted to avoid high acetylene content in the vented inert gas, which would cause waste. The acetylene gas absorbed by the low-temperature methanol circulation is heated in the tail gas stripping tower, and the stripped acetylene gas is recovered via pressure differential to the acetylation reaction system for recycling.

[0015] The acetylene gas vented from the acetylene reaction system first enters a water washing tower, where water washing removes some impurities and soluble components carried in the gas, thus achieving preliminary purification of the gas.

[0016] After the exhaust gas is discharged from the top of the water washing tower, it enters the liquid ring compressor for compression to increase the pressure of the exhaust gas.

[0017] The mechanical seal water of the liquid ring compressor plays a role in sealing and cooling during the compression process. After being cooled by the mechanical seal water heat exchanger, the mechanical seal water is returned to the top of the water washing tower for recycling, reducing resource waste.

[0018] The compressed exhaust gas enters the precooler, which further reduces the temperature, causing some of the components in the exhaust gas to condense.

[0019] The pre-cooled exhaust gas enters the methanol absorption tower, where it comes into countercurrent contact with methanol. The methanol absorbs the effective components in the exhaust gas, such as acetylene, thereby reducing the concentration of harmful components in the exhaust gas.

[0020] The solution at the bottom of the methanol absorption tower enters the tail gas desorption tower, where the absorbed gas components are desorbed from the methanol solution through heating and other means.

[0021] The advantages of this utility model are:

[0022] (1) The system of this utility model can be used in the acetylation reaction device of the in-service chemical acetylation aldehyde process for the production of 1,4-butanediol (BDO).

[0023] (2) The present invention has a large load elasticity. As the load of the main reaction system is adjusted, the present invention can be adjusted synchronously, and the production process is relatively stable.

[0024] (3) The internal water circulation and methanol circulation design of this utility model is reasonable and does not cause excessive waste of resources.

[0025] (4) The reaction venting acetylene gas recovered by the system of this utility model can reduce the unit consumption of calcium carbide in the device, save production costs, and at the same time reduce the carbon emission pressure caused by environmentally friendly burning.

[0026] (5) This utility model transforms the traditional acetylene reaction venting and incineration into the collection, low-temperature methanol absorption, desorption and recovery, avoiding the waste of acetylene gas, reducing the unit consumption of calcium carbide in the device, saving production costs, and at the same time reducing the carbon emission pressure caused by environmentally friendly incineration, with a high recovery rate. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the system structure of this utility model. Detailed Implementation

[0029] To make the objectives, technical solutions and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0030] like Figure 1As shown, a tail gas recovery system for the acetylene reaction in the 1,4-butanediol production process using the acetylene-aldehyde method includes a water washing tower 1, a liquid ring compressor 2, a mechanical seal water heat exchanger 3, a precooler 4, a methanol absorption tower 5, a methanol heat exchanger 6, a tail gas stripping tower 7, and a stripping tower medium heat exchanger 8. The acetylene tail gas outlet of the acetylene reaction system is connected to the gas inlet of the water washing tower 1. The gas outlet at the top of the water washing tower 1 is connected to the inlet of the liquid ring compressor 2. The mechanical seal water outlet of the liquid ring compressor 2 is connected to the inlet of the mechanical seal water heat exchanger 3. The outlet of the mechanical seal water heat exchanger 3 is connected to the top inlet of the water washing tower 1. The gas outlet of the liquid ring compressor 2 is connected to the gas inlet of the precooler 4. The gas outlet of the precooler 4 is connected to the... The lower gas inlet of the methanol absorption tower 5 is connected, and the bottom solution outlet of the methanol absorption tower 5 is connected to the top solution inlet of the tail gas desorption tower 7. The methanol heat exchanger 6 is provided with a normal temperature methanol inlet pipeline 16, a heat-exchanged methanol outlet pipeline 17, a low temperature methanol inlet pipeline 18, and a low temperature methanol outlet pipeline 19. The heat-exchanged methanol outlet pipeline 17 of the methanol heat exchanger 6 is connected to the methanol inlet at the top of the methanol absorption tower 5. The solution outlet of the desorption tower medium heat exchanger 8 is connected to the bottom solution inlet of the tail gas desorption tower 7. The top of the tail gas desorption tower 7 is provided with a gas outlet, and the bottom of the tail gas desorption tower 7 is also provided with a methanol outlet, which is connected to the normal temperature methanol inlet pipeline 16 of the methanol heat exchanger 6.

[0031] A water washing liquid pump circulation and discharge device 9 is connected to the bottom of the water washing tower 1.

[0032] The precooler 4 is provided with a precooling agent inlet pipeline 10 and a precooling agent outlet pipeline 11.

[0033] There are two precoolers 4, one of which is in operation and the other is on standby.

[0034] The methanol outlet at the bottom of the tail gas analysis tower 7 is connected to a pump 12. The outlet of the pump 12 is connected to the ambient temperature methanol inlet pipeline 16 of the methanol heat exchanger 6. The outlet of the pump 12 is also connected to a methanol discharge pipeline 13.

[0035] The gas outlet at the top of the tail gas analysis tower 7 is connected to a gas discharge pipeline 14.

[0036] like Figure 1As shown, the acetylene gas vented from the acetylene reaction system enters the bottom of the water washing tower 1 through a pipeline. Its main function is to remove impurities from the vented acetylene gas. After washing, the acetylene gas enters the liquid ring compressor 2 from the top of the water washing tower 1, increasing the acetylene gas pressure to facilitate methanol absorption. The mechanical seal water of the liquid ring compressor 2 is cooled by the mechanical seal water heat exchanger 3 and enters the water washing tower 1 from the top under its own pressure, making counter-current contact with the acetylene gas in the water washing tower 1 for washing. The mechanical seal water heat exchanger 3 uses circulating water, ensuring its reuse and preventing waste. The water washing liquid at the bottom of the water washing tower 1 is circulated using a pump for forced circulation. Depending on the liquid level, the liquid is discharged to other production units for use. The pressurized acetylene enters the precooler 4 for cooling, removing residual moisture. The chilled water (-7℃) exchanged in the precooler 4 is circulated. The precooler 4 is operated with one unit on and one unit on standby to prevent frost buildup during precooling from affecting system operation. Pre-cooled acetylene gas enters methanol absorption tower 5 through a pipeline. The system is replenished with ambient temperature methanol through ambient temperature methanol inlet pipeline 16. This ambient temperature methanol then enters methanol absorption tower 5 via methanol heat exchanger 6. During the replenishment of ambient temperature methanol, low-temperature methanol (-60℃) can be used in the shell side of the heat exchanger to cool the ambient temperature methanol in the system. This low-temperature methanol is recycled and not wasted. By controlling the pressure of methanol absorption tower 5 and tail gas desorption tower 7, the pressure difference is used to transport the methanol-acetylene gas-absorbing solution to tail gas desorption tower 7 through a pipeline. After the methanol-acetylene gas solution enters tail gas desorption tower 7, the temperature of the circulating ethylene glycol at the bottom of tail gas desorption tower 7 is adjusted by controlling the temperature and flow rate of the medium in the shell side of the desorption tower medium heat exchanger 8, thereby increasing the desorption rate. By analyzing the concentration of circulating methanol in the system, it is determined whether the methanol in the system should be discharged and collected. Based on the pressure and acetylene gas separation analysis of the tail gas stripping tower 7, acetylene gas with a stripping concentration >96% is recovered and used in the acetylation reaction system through the gas discharge pipeline. If the acetylene gas concentration in the stripping tower is low, it indicates that inert gas is accumulating in the system and can be discharged in small quantities to the flare system through the discharge pipeline 15 at the top of the methanol absorption tower 5.

[0037] This invention considers the need to recycle various types of waste as much as possible. The compressor seal water is cooled by the seal water heat exchanger 3 and enters from the top of the water washing tower 1 under its own pressure, where it comes into countercurrent contact with the acetylene gas in the water washing tower 1 for washing. This recycling process avoids waste. A pump forces circulation at the bottom of the water washing tower 1, and the liquid is discharged to other production units for use depending on the liquid level. The pressurized acetylene enters the precooler 4 for cooling to remove residual moisture from the acetylene gas. The chilled water (-7℃) used for precooling and ventilation is circulated. The precooler 4 is configured with one unit on and one unit on standby to prevent frost formation during precooling from affecting system operation.

[0038] The temperature and flow rate of the medium in the shell side of the heat exchanger in the stripping tower are controlled to adjust the temperature of the circulating ethylene glycol at the bottom of the stripping tower, thereby increasing the stripping rate. The concentration of methanol circulating in the system is analyzed to determine whether to collect and discharge the methanol from the system. Based on the pressure and acetylene gas fraction analysis of the stripping tower, acetylene gas with a stripping concentration >96% is recovered via pipeline for use in the acetylation reaction system. If the acetylene gas concentration in the stripping tower is low, it indicates that inert gases are accumulating in the system, and a small amount can be discharged to the flare system via pipeline.

[0039] This invention recovers the effective components from exhaust gas through absorption and desorption processes, thereby improving the utilization rate of raw materials and reducing production costs.

[0040] This invention treats exhaust gas, reducing the emission of harmful components and minimizing environmental pollution.

[0041] The various devices in this invention are connected by pipelines to form a complete recycling system, achieving efficient utilization of materials and energy. For example, the recycling of mechanical seal water, methanol, and heat recovery all help reduce the system's energy consumption.

[0042] This invention treats exhaust gas, reducing the concentration of combustible gases in the exhaust gas and minimizing safety hazards during exhaust gas emission.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A system for recovering tail gas from the acetylation reaction in the 1,4-butanediol production process using the acetylation-aldehyde method, characterized in that: The system includes a water washing tower, a liquid ring compressor, a mechanical seal water heat exchanger, a precooler, a methanol absorption tower, a methanol heat exchanger, a tail gas desorption tower, and a desorption tower medium heat exchanger. The acetylene tail gas outlet of the acetylene reaction system is connected to the gas inlet of the water washing tower. The gas outlet at the top of the water washing tower is connected to the inlet of the liquid ring compressor. The mechanical seal water outlet of the liquid ring compressor is connected to the inlet of the mechanical seal water heat exchanger. The outlet of the mechanical seal water heat exchanger is connected to the top inlet of the water washing tower. The gas outlet of the liquid ring compressor is connected to the gas inlet of the precooler. The gas outlet of the precooler is connected to the gas inlet at the bottom of the methanol absorption tower. The methanol absorption tower has its bottom solution outlet connected to the top solution inlet of the tail gas desorption tower. The methanol heat exchanger is equipped with a room temperature methanol inlet pipeline, a heat-exchanged methanol outlet pipeline, a low temperature methanol inlet pipeline, and a low temperature methanol outlet pipeline. The heat-exchanged methanol outlet pipeline of the methanol heat exchanger is connected to the methanol inlet at the top of the methanol absorption tower. The solution outlet of the desorption tower medium heat exchanger is connected to the bottom solution inlet of the tail gas desorption tower. The tail gas desorption tower has a gas outlet at the top and a methanol outlet at the bottom. The methanol outlet is connected to the room temperature methanol inlet pipeline of the methanol heat exchanger.

2. The acetylene reaction tail gas recovery system for the production process of 1,4-butanediol in the acetylene aldehyde method according to claim 1, characterized in that: A water washing liquid pump circulation and discharge device is connected to the bottom of the water washing tower.

3. The acetylene reaction tail gas recovery system for the production process of 1,4-butanediol in the acetylene aldehyde method according to claim 1, characterized in that: The precooler is equipped with a precooling inlet pipeline and a precooling outlet pipeline.

4. The acetylation reaction tail gas recovery system in the 1,4-butanediol production process of the acetylation aldehyde method according to claim 1, characterized in that: The precooler is provided in two units, with one precooler in operation and the other on standby.

5. The acetylene reaction tail gas recovery system in the 1,4-butanediol production process by acetylene aldehyde method according to claim 1, characterized in that: A pump is connected to the methanol outlet at the bottom of the tail gas desorption tower. The pump outlet is connected to the ambient temperature methanol inlet pipeline of the methanol heat exchanger, and the pump outlet is also connected to a methanol discharge pipeline.

6. The acetylene reaction tail gas recovery system in the 1,4-butanediol production process by acetylene aldehyde method according to claim 1, characterized in that: The gas outlet at the top of the exhaust gas analysis tower is connected to a gas discharge pipeline.

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