Dehydration device for tetrahydrofuran

Abstract

The utility model relates to a dehydration device for tetrahydrofuran, which comprises a rectification mechanism, an adjusting mechanism, a steam permeable membrane component and a heat energy utilization mechanism, one end of the adjusting mechanism is connected with the rectification mechanism, and the other end of the adjusting mechanism is connected with the steam permeable membrane component; one end of the heat energy utilization mechanism is communicated with the finished product side of the steam permeable membrane assembly, and the other end is communicated with the rectification mechanism. The heat energy utilization mechanism comprises a waste heat reboiler, a buffer tank, a cooler, a material transfer pump, a finished product condenser and a product tank; the finished product side of the steam permeable membrane component is communicated with the waste heat reboiler; an outlet of the waste heat reboiler is communicated with the buffer tank, the buffer tank is communicated with the cooler, the transfer pump is communicated with the finished product condenser, and the finished product condenser is communicated with the product tank. According to the device, through negative pressure operation of the rectifying tower, heat consumption is reduced, and heat recycling of a membrane finished product discharged from the steam permeable membrane assembly is achieved through the heat energy utilization mechanism.

Description

Technical Field

[0001] The utility model relates to the field of dehydration and reuse of organic solvents, in particular to a dehydration device for tetrahydrofuran. Background Art

[0002] Tetrahydrofuran is a kind of heterocyclic organic compound and one of the strongest polar ethers. It is used as a medium-polar solvent in chemical reactions and extractions. Tetrahydrofuran has good solubility in many organic substances and is widely used as a reactive solvent, known as the "universal solvent". In industrial production, when tetrahydrofuran is used as a solvent, impurities such as water are often introduced, making tetrahydrofuran unable to be reused due to impurities and being directly discarded, which is both wasteful and pollutes the environment.

[0003] In recent years, with the increasing demand for high-purity tetrahydrofuran, the further dehydration and purification of tetrahydrofuran have attracted more and more attention. Currently, tetrahydrofuran is mainly recovered by atmospheric distillation. Under atmospheric pressure, an azeotrope of tetrahydrofuran and water is obtained by distillation separation. This azeotrope still contains a certain amount of water. Since the water exists in the form of an azeotrope, it is impossible to separate tetrahydrofuran from the water in the azeotrope by conventional distillation or fractional distillation means, so it cannot meet certain extremely low water requirements, and this process has high energy consumption and cost.

[0004] Vapor permeation (abbreviated as VP) originated from pervaporation technology and is a technology between pervaporation and gas membrane separation. Its principle also relies on the pressure difference across the membrane as the driving force, and uses the different dissolution (adsorption) and diffusion rates of the mixture components on the membrane to achieve component separation. Vapor permeation is a gas-phase feed, and the permeate-side material exits in the gas phase. Tetrahydrofuran dehydration is achieved by coupling distillation and vapor permeation. However, the azeotrope of tetrahydrofuran and water obtained by distillation needs to pass through an evaporator and a superheater to reach the gas phase, enter the membrane module for dehydration, and then still needs to be condensed into a liquid by circulating cooling water and stored, with high energy consumption. There is an urgent need for a tetrahydrofuran dehydration device with reduced energy consumption. Summary of the Invention

[0005] The purpose of the utility model is to provide a tetrahydrofuran dehydration device with reduced energy consumption.

[0006] To achieve the purpose of the utility model, the technical solution is as follows:

[0007] A dehydration device for tetrahydrofuran includes: a distillation mechanism, a regulating mechanism, a vapor permeation membrane module, and a heat energy utilization mechanism, wherein: one end of the regulating mechanism is connected to the distillation mechanism, and the other end is connected to the vapor permeation membrane module; one end of the heat energy utilization mechanism is communicated with the finished product side of the vapor permeation membrane module, and the other end of the heat energy utilization mechanism is communicated with the distillation mechanism.

[0008] Furthermore, the rectification mechanism includes a rectification column and a steam reboiler, and the steam reboiler is arranged at the bottom of the column still of the rectification column;

[0009] The thermal energy utilization mechanism includes a waste heat reboiler, a buffer tank, a cooler, a transfer pump, a finished product condenser and a product tank; the finished product side of the vapor permeation membrane module is communicated with the waste heat reboiler; the outlet of the waste heat reboiler is communicated with the buffer tank, the buffer tank is communicated with the cooler, the cooler is communicated with the transfer pump, the transfer pump is communicated with the finished product condenser, and the finished product condenser is communicated with the product tank.

[0010] Furthermore, the buffer tank is a pressure tank; a pipeline directly connected to the finished product side of the vapor permeation membrane module is also provided at the inlet of the buffer tank; a pipeline directly connected to the finished product condenser is also provided at the outlet of the buffer tank.

[0011] Furthermore, the regulation mechanism includes a vacuum unit, a primary condenser, a secondary condenser, a reflux tank, a reflux pump, a distillate temporary storage tank A, a distillate temporary storage tank B, a membrane feed pump, an evaporator and a superheater; the inlet of the primary condenser is connected to the top of the rectification column, the gas phase outlet of the primary condenser is connected to the secondary condenser, and the secondary condenser is connected to the vacuum unit;

[0012] The aqueous phase outlets of the primary condenser and the secondary condenser are both connected to the inlet of the reflux tank, the outlet of the reflux tank is connected to the reflux pump, and the reflux pump is simultaneously connected to the inlet of the top of the rectification column, the distillate temporary storage tank A and the distillate temporary storage tank B;

[0013] Both the distillate temporary storage tank A and the distillate temporary storage tank B are connected to the inlet of the membrane feed pump, the outlet of the membrane feed pump is connected to the evaporator, the evaporator is connected to the superheater, and the superheater is connected to the vapor permeation membrane module.

[0014] Furthermore, on-line detection devices are provided on both the distillate temporary storage tank A and the distillate temporary storage tank B; a pipeline is also provided at the outlets of the distillate temporary storage tank A and the distillate temporary storage tank B and is connected to a transfer pump, and the mixed liquid that does not meet the membrane inlet conditions is sent out through the transfer pump.

[0015] Furthermore, the permeate side of the vapor permeation membrane module is sequentially connected to a permeate condenser, a permeate storage tank and a permeate pump.

[0016] Furthermore, the rectification column operates continuously under negative pressure, the operating temperature is 50 - 65°C, and the operating pressure is -0.03 MPaG. The operating temperature of the vapor permeation membrane module is 100 - 115°C, and the operating pressure is 0.2 - 0.35 MPaG.

[0017] Furthermore, the position of the liquid phase return port in the waste heat reboiler is higher than the liquid level height in the column still of the rectification column.

[0018] Compared with the prior art, the remarkable advantages of the present utility model are as follows: The dehydration device for tetrahydrofuran provided by the present utility model reduces heat consumption through the negative pressure operation of the rectification column, and realizes heat reuse for the membrane products coming out of the vapor permeation membrane module through the heat energy utilization mechanism. The temperature difference between the negative pressure operation temperature of the rectification column and the temperature of the membrane products coming out of the vapor permeation membrane module not only realizes heat utilization but also reduces the heat consumption of the rectification column. In addition, the negative pressure operation can make the water content in the azeotrope of water and tetrahydrofuran lower, improving the dehydration efficiency. Moreover, the adjustment mechanism ensures that the feed liquid entering the vapor permeation membrane module meets the membrane inlet conditions, ensuring the dehydration effect and prolonging the service life of the membrane. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the present utility model.

[0020] In the figure, 11 is a steam reboiler, 12 is a rectification column, 21 is a primary condenser, 22 is a secondary condenser, 23 is a vacuum unit, 24 is a reflux drum, 25 is a reflux pump, 26 is a distillate temporary storage tank A, 27 is a distillate temporary storage tank B, 28 is a membrane feed pump, 29 is an evaporator, 291 is a superheater, 30 is a vapor permeation membrane module, 41 is a waste heat reboiler, 42 is a buffer tank, 43 is a cooler, 44 is a transfer pump, 45 is a product condenser, 46 is a product tank, 47 is a product pump, 48 is a transfer pump, 31 is a permeate condenser, 32 is a permeate storage tank, 33 is a permeate pump. Detailed Embodiments

[0021] The following will describe in detail the embodiments of the present utility model with reference to the accompanying drawings.

[0022] As Figure 1 shown, a dehydration device for tetrahydrofuran includes: a rectification mechanism, an adjustment mechanism, a vapor permeation membrane module 30, and a heat energy utilization mechanism. One end of the adjustment mechanism is connected to the rectification mechanism, and the other end is connected to the vapor permeation membrane module 30. One end of the heat energy utilization mechanism is communicated with the finished product side of the vapor permeation membrane module 30, and the other end of the heat energy utilization mechanism is communicated with the rectification mechanism.

[0023] The rectification mechanism includes a rectification column 12 and a steam reboiler 11. The reboiler is arranged at the bottom of the column kettle of the rectification column 12. The aqueous tetrahydrofuran mother liquor enters the rectification column 12 from the middle of the column and is heated by the steam reboiler 11, and the gas of the azeotrope of tetrahydrofuran and water formed is sent out from the top of the column.

[0024] The regulating mechanism includes a vacuum unit 23, a primary condenser 21, a secondary condenser 22, a reflux drum 24, a reflux pump 25, a distillate temporary storage tank A 26, a distillate temporary storage tank B 27, a membrane feed pump 28, an evaporator 29, and a superheater 291. Among them, the inlet of the primary condenser 21 is connected to the top of the rectification column 12. The gas phase outlet of the primary condenser 21 is connected to the secondary condenser 22, and the secondary condenser 22 is connected to the vacuum unit 23 to provide power for the unit. The aqueous phase outlets of the primary condenser 21 and the secondary condenser 22 are both connected to the inlet of the reflux drum 24. The outlet of the reflux drum 24 is connected to the reflux pump 25, and the reflux pump 25 is simultaneously connected to the inlet of the top of the rectification column 12, the distillate temporary storage tank A 26, and the distillate temporary storage tank B 27. The distillate temporary storage tank A 26 and the distillate temporary storage tank B 27 are both connected to the inlet of the membrane feed pump 28. The outlet of the membrane feed pump 28 is connected to the evaporator 29, and the evaporator 29 is connected to the superheater 291.

[0025] Furthermore, on-line detection devices are provided on both the distillate temporary storage tank A 26 and the distillate temporary storage tank B 27. The on-line detection device detects whether the mixture of tetrahydrofuran and water in the tank meets the membrane inlet conditions, such as pH value, solid residue, etc. When the membrane inlet conditions are met, the pipelines of the distillate temporary storage tank A 26, the distillate temporary storage tank B 27 and the membrane feed pump 28 are opened, and the mixture enters the evaporator 29. After becoming saturated gas in the superheater 291, it enters the vapor permeation membrane module 30 for further separation of tetrahydrofuran and water. Even further, there is also a pipeline connecting the outlets of the distillate temporary storage tank A 26 and the distillate temporary storage tank B 27 to a transfer pump 48. The mixture that does not meet the membrane inlet conditions is transported to the mother liquor tank through the transfer pump 48, so that it re-enters the rectification column 12 for further reaction.

[0026] The heat energy utilization mechanism includes a waste heat reboiler 41, a buffer tank 42, a cooler 43, a transfer pump 44, a finished product condenser 45, and a product tank 46. The finished product side of the vapor permeation membrane module 30 is communicated with the waste heat reboiler 41, and the waste heat reboiler 41 is communicated with the bottom of the rectification column 12. Through the waste heat reboiler 41, the high-temperature gas of the membrane-finished tetrahydrofuran exchanges heat with the mother liquor in the bottom of the column through the waste heat reboiler 41, reducing heat energy consumption. Further, the position of the liquid phase return port in the waste heat reboiler is higher than the liquid level height in the bottom of the rectification column 12. To ensure that in the rectification column, the liquid phase on the upper tray flows through the waste heat reboiler preferentially. After heat exchange in the waste heat reboiler, it returns to the bottom of the column and is then heated by the steam reboiler. The outlet of the waste heat reboiler 41 is communicated with the buffer tank 42, and the buffer tank 42 is communicated with the cooler 43 and the transfer pump 44. The transfer pump 44 is communicated with the finished product condenser 45, and the finished product condenser 45 is communicated with the product tank 46. The finished product of tetrahydrofuran is sent out through the finished product condenser 45, the product tank 46, and the finished product pump 47.

[0027] Further, the buffer tank 42 is a pressure tank. By means of the pressure tank, the heat exchange temperature in the waste heat reboiler 41 can be maintained, preventing the pressure from dropping, which would otherwise cause the temperature to decrease and the heat exchange efficiency to decline. Further, a pipeline directly connected to the finished product side of the vapor permeation membrane module 30 is provided at the inlet of the buffer tank 42; a pipeline directly connected to the finished product condenser 45 is provided at the outlet of the buffer tank 42. The pressure in the buffer tank 42 is maintained constant through these two pipelines.

[0028] On the permeate side of the vapor permeation membrane module 30, a permeate condenser 31, a permeate storage tank 32, and a permeate pump 33 are sequentially connected. The vapor partial pressure difference between the two sides of the membrane is formed by means of vacuum pumping and condensation. The permeate gas enters the condenser under the suction of the vacuum unit, and the condensed permeate is discharged through the permeate pump 33.

[0029] The aqueous tetrahydrofuran mother liquor can be pumped from the mother liquor tank by a pump into the middle of the distillation column 12. The distillation column 12 operates continuously under negative pressure. The bottom of the column is heated to vaporize. After the total reflux is stable, the azeotrope gas of light components, tetrahydrofuran and water, is withdrawn from the top of the column. It passes through the first-stage condenser 21 and the second-stage condenser 22 at the top of the column, reaches the reflux tank 24, and after the reflux pump 25, part of it is refluxed to the top of the column, and part of it is withdrawn to the distillate temporary storage tank A26 or the distillate temporary storage tank B27 (reflux ratio 1:1). The waste liquid at the bottom of the column is cooled by the bottom cooler 43 and then sent out by the bottom pump.

[0030] The azeotrope meeting the membrane inlet conditions is pumped by the membrane feed pump 28 into the evaporator 29 and the superheater 291 in sequence, and then enters the vapor permeation membrane module 30 in the form of gas. The vapor permeation membrane module 30 can be composed of multiple membrane modules connected in series. The water in the azeotrope permeates from the upstream side of the membrane to the permeate side of the membrane through the membrane module. The membrane-finished tetrahydrofuran vapor with less water content obtained on the upstream side (finished product side) of the last-stage membrane module is heat-exchanged through the waste heat reboiler 41, then passes through the buffer tank 42, the cooler 43, the transfer pump 44, the finished product condenser 45, the product tank 46, and the finished product pump 47, and the tetrahydrofuran finished product is sent out.

[0031] Among them, the distillation column 12 operates continuously under negative pressure, with an operating temperature of 50 - 65 °C and an operating pressure of -0.03 MPaG. The operating temperature of the vapor permeation membrane module 30 is 100 - 115 °C, and the operating pressure is 0.2 - 0.35 MPaG.

Claims

1. A dehydration device for tetrahydrofuran, comprising: A distillation mechanism, a regulating mechanism, a steam permeable membrane assembly (30), and a heat energy utilization mechanism, characterized in that: one end of the regulating mechanism is connected to the distillation mechanism, and the other end is connected to the steam permeable membrane assembly (30); one end of the heat energy utilization mechanism is connected to the finished product side of the steam permeable membrane assembly (30), and the other end of the heat energy utilization mechanism is connected to the distillation mechanism.

2. The dehydration device for tetrahydrofuran according to claim 1, characterized in that: The distillation mechanism comprises a distillation tower (12) and a steam reboiler (11), wherein the steam reboiler (11) is arranged at the bottom of the tower kettle of the distillation tower (12); The heat energy utilization mechanism comprises a waste heat reboiler (41), a buffer tank (42), a cooler (43), a material transfer pump (44), a finished product condenser (45) and a product tank (46); the finished product side of the steam permeation membrane assembly (30) is connected to the waste heat reboiler (41); the outlet of the waste heat reboiler (41) is connected to the buffer tank (42), the buffer tank (42) is connected to the cooler (43), the cooler (43) is connected to the material transfer pump (44), the material transfer pump (44) is connected to the finished product condenser (45), and the finished product condenser (45) is connected to the product tank (46).

3. The dehydration device for tetrahydrofuran (THF) according to claim 2, characterized in that: The buffer tank (42) is a pressure tank; the inlet of the buffer tank (42) is also provided with a pipeline directly connected to the finished product side of the steam permeation membrane assembly (30); the outlet of the buffer tank (42) is also provided with a pipeline directly connected to the finished product condenser (45).

4. The dehydration device for tetrahydrofuran according to claim 1 or 2, characterized in that: The regulating mechanism comprises a vacuum unit (23), a primary condenser (21), a secondary condenser (22), a reflux tank (24), a reflux pump (25), a distillate temporary storage tank A (26), a distillate temporary storage tank B (27), a membrane feed pump (28), an evaporator (29) and a superheater (291); the inlet of the primary condenser (21) is connected to the top of the distillation tower (12), the gas phase outlet of the primary condenser (21) is connected to the secondary condenser (22), and the secondary condenser (22) is connected to the vacuum unit (23); The water phase outlets of the primary condenser (21) and the secondary condenser (22) are both connected to the inlet of the reflux tank (24), the outlet of the reflux tank (24) is connected to a reflux pump (25), and the reflux pump (25) is simultaneously connected to the top inlet of the distillation tower (12), the distillate temporary storage tank A (26), and the distillate temporary storage tank B (27); The distillate temporary storage tank A (26) and the distillate temporary storage tank B (27) are both connected to the inlet of the membrane feed pump (28), the outlet of the membrane feed pump (28) is connected to the evaporator (29), the evaporator (29) is connected to the superheater (291), and the superheater (291) is connected to the steam permeation membrane assembly (30).

5. The dehydration device for tetrahydrofuran according to claim 4, characterized in that: Both the distillate temporary storage tank A (26) and the distillate temporary storage tank B (27) are provided with an online detection device; and both the outlets of the distillate temporary storage tank A (26) and the distillate temporary storage tank B (27) are provided with a pipeline connected to a delivery pump (48), and the mixed liquid that does not meet the membrane entry conditions is delivered through the delivery pump (48).

6. The dehydration device for tetrahydrofuran according to claim 1 or 2, characterized in that: The permeate side of the steam permeation membrane module (30) is connected to a permeate condenser (31), a permeate storage tank (32), and a permeate pump (33) in sequence.

7. The dehydration device for tetrahydrofuran according to claim 1, characterized in that: The distillation tower (12) is operated continuously under negative pressure, with an operating temperature of 50-65°C and an operating pressure of -0.03MPaG.

8. The dehydration device for tetrahydrofuran according to claim 1, characterized in that: The operating temperature of the steam permeable membrane module (30) is 100-115°C, and the operating pressure is 0.2-0.35 MPaG.

9. The dehydration device for tetrahydrofuran according to claim 2, characterized in that: The position of the liquid phase return port in the waste heat reboiler is higher than the liquid level in the bottom of the distillation tower (12).

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