Energy-saving device for purifying tetrahydrofuran

Abstract

The utility model discloses an energy-saving device for purifying tetrahydrofuran, which comprises a preheater, a membrane component and a rectifying tower, and is characterized by further comprising a compressor, the preheater is connected to the upper part of the rectifying tower, an outlet in the upper part of the rectifying tower is connected with an inlet of the membrane component, and an interception side outlet of the membrane component is connected with an inlet of the compressor. An outlet of the compressor is connected to an inlet in the middle of the rectifying tower. The process has the beneficial effects that the process is simpler and more convenient to operate, the operation pressure is relatively low, and the requirement on equipment is low.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of membrane separation, specifically relates to a kind of energy-saving device of tetrahydrofuran purification. BACKGROUND

[0002] Tetrahydrofuran is also known as 1,4-epoxybutane, abbreviated as THF, is a colorless transparent, miscible with water, is a good performance organic liquid, because with fast dissolving speed, good penetration and diffusion of resin surface and internal characteristics and get widely used.Especially for polyvinyl chloride, polyvinylidene fluoride and its copolymer, can get low viscosity solution, thus used in surface coating, protective coating, adhesive and film manufacturing.Also used in ink, paint remover, extractant, artificial leather surface treatment agent liquid chromatography solvent.At the same time, tetrahydrofuran is also the intermediate for manufacturing butadiene, nylon, polybutylene glycol ether, gamma-butyrolactone, polyvinylpyrrolidone, tetrahydrothiophene.Current domestic and foreign industrial THF purification method, generally used is pressure swing distillation, membrane separation etc.But pressure swing distillation equipment is more, and occupies larger area, and has certain requirements for operating personnel;Single membrane separation technology to achieve high purity THF separation requirements, the required membrane area is huge, cost is higher.Therefore, to find energy-efficient, easy to operate high purity tetrahydrofuran recovery method has important significance. SUMMARY

[0003] The utility model is directed to provide a kind of energy-saving device of tetrahydrofuran purification.

[0004] To achieve the above object, the utility model provides the following technical scheme:

[0005] A kind of energy-saving device of tetrahydrofuran purification, including preheater, membrane module and rectifying tower, still include compressor, the preheater is connected to the upper portion of rectifying tower, the outlet of rectifying tower upper portion is connected the import of membrane module, the import of compressor is connected to the outlet of membrane module, the import of rectifying tower middle portion is connected to the outlet of compressor.

[0006] Preferably, condenser is further provided between the outlet of rectifying tower upper portion and membrane module, the condenser includes first outlet and second outlet, the first outlet of condenser is connected with the import of membrane module, the second outlet of condenser is communicated with the reflux port of rectifying tower by pipeline.

[0007] Preferably, the membrane module is composed of a plurality of membrane separators in series, at least one heat supplement device is provided between the membrane separators.

[0008] Preferably, the outlet on the permeate side of the membrane module is connected to a permeate condenser, and the outlets on the permeate side of several membrane separators are all connected to the same permeate condenser. A permeate tank and a vacuum pump are connected to the permeate condenser, and a permeate pump is connected to the outlet of the permeate tank.

[0009] Preferably, a condenser is provided between the outlet of the upper part of the distillation column and the membrane module, the outlet of the condenser is connected to the inlet of the membrane module, and the reflux port of the condenser is connected to the upper part of the distillation column through a pipeline.

[0010] Preferably, a superheater is provided between the first outlet of the condenser and the membrane module.

[0011] Preferably, a reboiler is provided at the bottom of the distillation column.

[0012] Preferably, the discharge port at the bottom of the distillation column is connected to the heat source inlet of the preheater.

[0013] Preferably, the theoretical number of trays in the distillation column is 24; the preheater is connected to the upper part of the distillation column, specifically entering from the 6th theoretical tray; the compressor outlet is connected to the inlet in the middle part of the distillation column, specifically entering from the 12th theoretical tray.

[0014] Preferably, the discharge port at the bottom of the distillation column is connected to the heat source inlet of the preheater.

[0015] The beneficial effects of this invention are: compared to pressure swing distillation, this process is simpler to operate, has a relatively lower operating pressure, and requires less equipment. Compared to pervaporation membrane dehydration, the process combining pervaporation membrane with a heat pump and distillation column requires approximately six times less membrane area than a single membrane separation process, resulting in significant cost reduction. Furthermore, the larger the throughput, the better the economic benefits. Energy savings exceed 35%. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] The components include: 1. Preheater; 2. Separate condenser; 3. Reboiler; 4. Superheater; 5. Membrane module; 6. Compensator; 7. Compressor; 8. Permeate condenser; 9. Permeate tank; 10. Permeate pump; 11. Vacuum pump; 12. Distillation column. Detailed Implementation

[0018] The technical solution of this patent will be further described in detail below with reference to specific embodiments.

[0019] like Figure 1As shown, this utility model discloses an energy-saving device for purifying tetrahydrofuran, comprising a preheater 1, a membrane module 5, and a distillation column 12. The mother liquor enters the upper part of the distillation column 12 through the preheater 1. The inlet of the membrane module 5 is connected to the outlet of the upper part of the distillation column 12, and the outlet of the membrane module 5 on the retard side is connected to the inlet of the middle part of the distillation column 12 through a compressor 7. A discharge port is provided at the bottom of the distillation column 12. The mother liquor is preheated by the preheater 1 and enters the upper part of the distillation column 12 for pressurized distillation into a gaseous state. The azeotrope of water and tetrahydrofuran enters the membrane module 5 from the top of the column. The permeate side of the membrane module 5 is used to extract water vapor through negative pressure. The remaining tetrahydrofuran and a small amount of water vapor enter the middle part of the distillation column 12 from the retard side through the compressor 7, and are finally discharged from the discharge port at the bottom of the distillation column 12 to obtain high-purity THF.

[0020] Membrane module 5 consists of several membrane separators connected in series. The outlet of the terminal membrane separator is connected to the inlet in the middle of the distillation column 12. Through multiple membrane separators connected in series, water vapor is extracted multiple times in membrane module 5, resulting in less water vapor and a higher THF concentration when it finally enters the middle of the distillation column 12.

[0021] At least one heat exchanger 6 is provided between several membrane separators for heat replenishment; the temperature of the azeotrope of THF and water gradually decreases as it passes through the membrane separators. Heat replenishment is provided between the membrane separators by installing heat exchangers 6 to maintain the temperature and prevent the azeotrope of THF and water from liquefying.

[0022] The outlet of the permeate side of several membrane separators is connected to a permeate condenser 8. The permeate condenser 8 is connected to a permeate tank 9 and a vacuum pump 11. The outlet of the permeate tank 9 is connected to a permeate pump 10 for discharging waste liquid. The vacuum pump 11 draws water vapor in the membrane module 5 into the permeate condenser 8 by means of negative pressure. The water vapor is liquefied in the permeate condenser 8 and discharged through the permeate pump 10.

[0023] A condenser 2 is installed between the outlet of the upper part of the distillation column 12 and the membrane module 5. The outlet of the condenser 2 is connected to the inlet of the membrane module 5. The reflux port of the condenser 2 is connected to the upper part of the distillation column 12 through a pipeline. The liquid is returned to the upper part of the distillation column 12 through the condenser 2 and reheated to a gaseous state. The gas passes through the condenser 2 and enters the membrane module for the next process.

[0024] A superheater 4 is provided between the condenser 2 and the membrane module 5; the superheater 4 maintains the temperature of the gas and prevents the gas from liquefying.

[0025] A reboiler 3 is provided at the bottom of the distillation column 12; the bottom of the distillation column 12 is heated by the reboiler 3, so that the gas at the bottom of the distillation column 12 is kept in a gaseous state and the liquid is re-vaporized into a gaseous state.

[0026] The discharge port at the bottom of the distillation column 12 is connected to the heat source inlet of the preheater 1. The product from the discharge port at the bottom of the distillation column 12 is gaseous and has high heat. By passing it through the heat source inlet of the preheater 1, the heat of the product is transferred to the preheater 1 to preheat the mother liquor, thereby improving the energy utilization rate and facilitating the cooling of the product to a liquid state.

[0027] The above-described apparatus can process mother liquor with a water content not exceeding 7.88% (the mother liquor is a mixture of THF and water). As a specific embodiment, the composition of THF and water in the mother liquor is 92.12:7.88.

[0028] Process: After heat exchange in preheater 1, the THF aqueous solution enters the upper part of distillation column 12 from the 6th theoretical tray. The temperature at the upper part of distillation column 12 is 100℃, and the pressure is 300kPaA. The column is pressurized for distillation, with 24 theoretical trays. The mother liquor is fed from the 6th feed tray. An azeotrope of tetrahydrofuran and water is collected from the top of the column. After passing through the top condenser 2, part of it is refluxed back to the top of the column at a reflux ratio of 0.65, and the rest is superheated in the superheater 4 before entering the membrane module 5 for separation. The operating pressure of the membrane module 5 is 300~450 kPaA. A supplementary heater 6 is installed between the membrane modules 5 for heat supplementation. The THF vapor with a low water content obtained from the permeate side is pressurized and heated by the compressor 7 and returned from the 12th theoretical tray of the distillation column 12 to the middle of the column to continue carrying water. The compressor 7 increases the temperature from 103℃ to 114℃ and the pressure from 300 kPaA to 400 kPaA. The permeate side is evacuated by a vacuum unit, and a large amount of water vapor is condensed by the permeate condenser 8, resulting in an aqueous solution in the permeate tank 9. This solution is then discharged by the permeate pump 10 to the wastewater treatment plant. The pressure on the permeate side is 2-3 kPaA. High-purity tetrahydrofuran is obtained at the bottom of the distillation column 12, where the temperature at the bottom of the column is 105.7℃.

[0029] In the above process, the operating pressure of membrane module 5 is 300~450 kPaA, and the corresponding tower pressure and compressor 7 outlet pressure can also be increased proportionally.

[0030] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An energy-saving device for purifying tetrahydrofuran, comprising a preheater (1), a membrane module (5), and a distillation column (12), characterized in that: It also includes a compressor (7), the preheater (1) is connected to the upper part of the distillation column (12), the outlet of the upper part of the distillation column (12) is connected to the inlet of the membrane module (5), the outlet of the membrane module (5) on the truncation side is connected to the inlet of the compressor (7), and the outlet of the compressor (7) is connected to the inlet of the middle part of the distillation column (12).

2. The energy-saving device for tetrahydrofuran purification according to claim 1, characterized in that: A condenser (2) is also provided between the outlet of the upper part of the distillation column (12) and the membrane module (5). The condenser (2) includes a first outlet and a second outlet. The first outlet of the condenser (2) is connected to the inlet of the membrane module (5), and the second outlet of the condenser (2) is connected to the reflux port of the distillation column (12) through a pipeline.

3. The energy-saving device for tetrahydrofuran purification according to claim 1, characterized in that: The membrane module (5) is composed of several membrane separators connected in series, and at least one heat exchanger (6) is provided between the membrane separators.

4. The energy-saving device for tetrahydrofuran purification according to claim 3, characterized in that: The outlet of the membrane module on the permeate side is connected to a permeate condenser (8), and the outlets of the permeate sides of several membrane separators are all connected to the same permeate condenser (8). The permeate condenser (8) is connected to a permeate tank (9) and a vacuum pump (11), and the outlet of the permeate tank (9) is connected to a permeate pump (10).

5. The energy-saving device for tetrahydrofuran purification according to claim 1, characterized in that: A condenser (2) is provided between the outlet of the upper part of the distillation column (12) and the membrane module (5). The outlet of the condenser (2) is connected to the inlet of the membrane module (5). The reflux port of the condenser (2) is connected to the upper part of the distillation column (12) through a pipeline.

6. The energy-saving device for tetrahydrofuran purification according to claim 5, characterized in that: An overheater (4) is provided between the first outlet of the condenser (2) and the membrane module (5).

7. The energy-saving device for tetrahydrofuran purification according to claim 1, characterized in that: The bottom of the distillation column (12) is equipped with a reboiler (3).

8. The energy-saving device for purifying tetrahydrofuran according to claim 1, characterized in that: The theoretical number of trays in the distillation column (12) is 24; the preheater (1) is connected to the upper part of the distillation column (12), specifically entering from the 6th theoretical tray of the distillation column (12); the outlet of the compressor (7) is connected to the inlet in the middle part of the distillation column (12), specifically entering from the 12th theoretical tray of the distillation column (12).

9. The energy-saving device for purifying tetrahydrofuran according to claim 1, characterized in that: The discharge port at the bottom of the distillation column (12) is connected to the heat source inlet of the preheater (1).

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