CN111116522B - Device and method for separating tetrahydrofuran-water mixture by single-tower extractive distillation - Google Patents
Device and method for separating tetrahydrofuran-water mixture by single-tower extractive distillation Download PDFInfo
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- CN111116522B CN111116522B CN202010062136.0A CN202010062136A CN111116522B CN 111116522 B CN111116522 B CN 111116522B CN 202010062136 A CN202010062136 A CN 202010062136A CN 111116522 B CN111116522 B CN 111116522B
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
- C07D307/06—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
- C07D307/08—Preparation of tetrahydrofuran
Abstract
The invention relates to a device for separating a tetrahydrofuran-water mixture by single-tower extractive distillation, which comprises an extractive distillation tower, a condenser, a reboiler, a reflux tank and a reflux pump. The invention uses pyrrolidone as an extracting agent and separates the mixture of tetrahydrofuran and water by a single extractive distillation tower. Feeding an extracting agent from the upper part of the extraction and rectification tower, feeding a raw material tetrahydrofuran-water mixture from the lower part of the extraction and rectification tower, carrying out multi-stage vapor-liquid mass transfer, obtaining a tetrahydrofuran product at the tower top, and extracting wastewater at the tower bottom. The single tower realizes the separation of the tetrahydrofuran-water system, solves the problem that the tetrahydrofuran-water system is difficult to separate because the tetrahydrofuran-water system forms an azeotrope under normal pressure, omits a conventional solvent recovery tower, and has the advantages of simple process, low energy consumption, high recovery rate and the like.
Description
Technical Field
The invention relates to a device and a method for separating a tetrahydrofuran-water mixture by single-tower extractive distillation, belonging to the field of chemical separation and purification.
Background
Tetrahydrofuran is an organic solvent with excellent performance, is particularly suitable for dissolving PVC, polyvinylidene chloride and butylaniline, and is widely used as a solvent for surface coatings, anticorrosive coatings, printing inks, magnetic tapes and film coatings and a reaction solvent for electroplating aluminum. Tetrahydrofuran is also an important organic synthetic raw material, and is mainly used as a raw material of medicines, pesticides and special rubber. In the process of medicine production, pharmaceutical enterprises use a large amount of tetrahydrofuran solvents to generate tetrahydrofuran-containing waste liquid, and the tetrahydrofuran in the waste liquid can be effectively recovered, so that the production cost can be reduced, and the environmental impact of waste can be reduced. But tetrahydrofuran is mutually soluble with water and can form the lowest azeotrope, so that the separation of tetrahydrofuran and water is difficult to realize by simple rectification.
The extractive distillation belongs to special distillation, and a third solvent is introduced in the distillation process so as to obviously improve the relative volatility of a system to be separated, so that the method is an effective means for separating azeotrope or near-boiling substances. The process for separating tetrahydrofuran-water mixtures by extractive distillation has been reported industrially. CN 200510016029.X discloses a method for analyzing tetrahydrofuran and water azeotrope by intermittent extraction and rectification by using 1,2-propylene glycol as an extracting agent, but the method adopts intermittent operation and is complex to operate. Huang Donghao et al (Shenyang chemical university journal, vol 29, no. 3, 2015) propose extractive distillation using dimethyl sulfoxide as extractant to separate tetrahydrofuran-water mixture. In the extraction and rectification process, because the dosage of the extracting agent is large, a solvent recovery tower is needed for recovering and utilizing the dimethyl sulfoxide. The larger solvent ratio increases the load of the extraction and rectification tower and the solvent recovery tower, so that the double-tower process flow has the defects of complex separation process, high energy consumption, large equipment investment and the like. In addition, because the process uses a high-boiling point solvent dimethyl sulfoxide (189 ℃) as an extracting agent, the temperature of a tower kettle of a solvent recovery tower is high, low-pressure steam cannot be used as a heat source of a reboiler of the solvent recovery tower, and the running cost is high. In order to reduce the energy consumption of double-tower rectification, han Shucui and the like (chemical engineering, volume 46, 11 th of 2018) couple pressure swing rectification and extractive rectification technologies, and a heat integration extractive rectification process for separating tetrahydrofuran-water by using dimethyl sulfoxide as an extractant is provided. Although the method can reduce the energy consumption of the process through heat integration, the coupling degree between the two towers is high, the process is complex, and the production control of the process is challenged.
Disclosure of Invention
In view of the defects of the prior art, the technical problem to be solved by the invention is to provide a device and a method for separating a tetrahydrofuran-water mixture by single-tower extractive distillation.
In order to solve the technical problem, the technical scheme of the invention is as follows: a device for separating tetrahydrofuran-water mixture by single-tower extractive distillation comprises an extractive distillation tower, a condenser, a reboiler, a reflux tank and a reflux pump;
the extraction and rectification tower is provided with an extractant feeding port and a raw material inlet at the middle upper part and the lower part respectively, a gas phase outlet at the top of the extraction and rectification tower is connected with an inlet at the hot end of a condenser, an outlet of the condenser is communicated with a feeding port of a reflux tank, a discharge port of the reflux tank is connected with an inlet of a reflux pump, a discharge port of the reflux pump is communicated with a reflux port of the extraction and rectification tower, a tower kettle of the extraction and rectification tower is connected with an inlet of a reboiler, and an outlet of the reboiler is communicated with the upper part of the tower kettle.
Preferably, the number of theoretical plates of the extractive distillation tower is 25 to 40, the feed inlet of the extractant is positioned at 3~1/2 of the tower, and the feed inlet is positioned at 5~5/6 of the tower.
The method for the device for separating the tetrahydrofuran-water mixture by single-tower extractive distillation comprises the following steps:
(1) The extractant pyrrolidone is fed into the extraction and rectification tower from an extractant feed inlet at the upper part of the middle part, and a mixture of tetrahydrofuran and water as a raw material is preheated and then fed into a raw material inlet at the lower part of the extraction and rectification tower to be in countercurrent contact with the extractant fed from the upper part of the extraction and rectification tower, so that multi-stage vapor-liquid mass transfer is carried out;
(2) Tetrahydrofuran steam at the top of the extraction rectifying tower is subjected to phase change through a condenser to form liquid-phase condensate;
(3) The liquid phase from the condenser is sent into a reflux tank, after the material discharged from the reflux tank is pressurized by a reflux pump, one part of the material is returned to the extraction and rectification tower as reflux, and the other part of the material is extracted as a tetrahydrofuran product;
(4) Feeding a part of the material discharged from the bottom of the extraction and rectification tower into a reboiler, returning the part of the material to the extraction and rectification tower after the material is partially vaporized under the heating action of steam, and directly discharging the other part of the material discharged from the bottom of the extraction and rectification tower as wastewater.
Preferably, the operating pressure of the extraction and rectification tower is 0.4 to 0.8 atm, and the reflux ratio is 0.5 to 3.5.
Preferably, the feeding mass flow ratio of the extracting agent to the tetrahydrofuran-water mixed solution is 0.001 to 0.01.
Preferably, the tetrahydrofuran content in the tetrahydrofuran-water mixture to be separated is 30 to 85 percent.
Compared with the prior art, the invention has the following beneficial effects: the invention adopts the low boiling point extractant pyrrolidone, can realize the effective separation of the tetrahydrofuran-water azeotropic mixture only by a single tower, does not need a solvent recovery tower, and has less equipment investment; the invention adopts a single-tower process, has simple flow, simple and convenient operation and low energy consumption.
The invention is described in further detail below with reference to the drawings and the detailed description.
Drawings
FIG. 1 is a ternary volatilization curve of water-tetrahydrofuran-pyrrolidone.
FIG. 2 is a flow chart of a single-tower extractive distillation process.
Detailed Description
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
As shown in fig. 1~2, a device for separating tetrahydrofuran-water mixture by single-tower extractive distillation comprises an extractive distillation tower T1, a condenser C1, a reboiler R1, a reflux tank V1 and a reflux pump P1;
an extractant feed port and a raw material inlet are respectively arranged at the middle upper part and the lower part of an extractive distillation column T1, a gas phase outlet at the top of the extractive distillation column T1 is connected with an inlet at the hot end of a condenser C1, an outlet of the condenser C1 is communicated with a feed port of a reflux tank V1, a discharge port of the reflux tank V1 is connected with an inlet of a reflux pump P1, a discharge port of the reflux pump P1 is communicated with a reflux port of the extractive distillation column T1, a tower kettle of the extractive distillation column T1 is connected with an inlet of a reboiler R1, and an outlet of the reboiler R1 is communicated with the upper part of the tower kettle.
In the embodiment of the invention, the theoretical plate number of the extraction and rectification tower T1 is 25 to 40, the extractant feed inlet is positioned at 3~1/2 of the tower 1/5363, and the raw material inlet is positioned at 5~5/6 of the tower.
The method for the device for separating the tetrahydrofuran-water mixture by single-tower extractive distillation comprises the following steps:
(1) The extractant pyrrolidone is fed into the extractive distillation tower T1 from the extractant feed inlet at the upper part of the middle part, and the mixture of the raw material tetrahydrofuran and water is preheated and then fed into the raw material inlet at the lower part of the extractive distillation tower T1 to be in countercurrent contact with the extractant fed from the upper part of the extractive distillation tower T1 for multi-stage vapor-liquid mass transfer;
(2) Tetrahydrofuran steam at the top of the extraction rectifying tower T1 is subjected to phase change through a condenser C1 to form liquid-phase condensate;
(3) The liquid phase from the condenser C1 is sent into a reflux tank V1, after the material discharged from the reflux tank V1 is pressurized by a reflux pump P1, one part of the material is returned to the extraction and rectification tower T1 as reflux, and the other part of the material is extracted as a tetrahydrofuran product;
(4) One part of the material discharged from the bottom of the extraction rectifying tower T1 is sent to a reboiler R1, under the heating action of steam, the material is returned to the extraction rectifying tower T1 after being partially vaporized, and the other part of the material discharged from the bottom of the extraction rectifying tower T1 is directly discharged as wastewater.
In the embodiment of the invention, pyrrolidone is selected as an extracting agent. Because the boiling point of pyrrolidone is between that of tetrahydrofuran and water, pyrrolidone is enriched between the feed inlet of the extractant and the feed inlet in the extractive distillation column T1. In the enrichment area of pyrrolidone, the azeotropic composition of tetrahydrofuran and water is broken, the relative volatility of tetrahydrofuran and water is increased, so that the tetrahydrofuran and water are separated, and the tetrahydrofuran is extracted from the top of the tower and the water is discharged from the bottom of the tower.
In the embodiment of the invention, the feeding mass flow ratio of the extracting agent to the tetrahydrofuran-water mixed solution is 0.001 to 0.01.
In the embodiment of the invention, the tetrahydrofuran content in the tetrahydrofuran-water mixture to be separated is 30 to 85 percent.
In the embodiment of the invention, the single-tower extractive distillation adopts decompression operation. As can be seen from the ternary isovolatility curves of water-tetrahydrofuran-pyrrolidone in FIG. 1, reducing the pressure is beneficial to increasing the relative volatility of water-tetrahydrofuran. Meanwhile, the operation pressure of the extraction rectifying tower T1 is 0.4 to 0.8 atm and the reflux ratio is 0.5 to 3.5 by considering the appropriate tower top temperature range.
Example 1
The tetrahydrofuran-water mixed solution has the feed flow of 1000kg/h,25 ℃, and the feed composition is as follows: 80% of tetrahydrofuran and 20% of water. The extractant pyrrolidone feed flow rate is 5 kg/h. The number of the T1 trays of the extraction and rectification tower is 45, the mixed liquid feeding plate is 43, and the extractant feeding plate is the 17 th plate. The operation pressure of the extractive distillation column T1 is 0.40atm, the reflux ratio is 2.2, and 802 kg/h is extracted from the top of the column. The purity of tetrahydrofuran extracted from the tower top is 99.73 percent; the tetrahydrofuran content in the water extracted from the tower bottom is 638ppm, and the pyrrolidone content is 1.56%. The yield of tetrahydrofuran was 99.98%.
Example 2
The tetrahydrofuran-water mixed solution has the feed flow of 1000kg/h,25 ℃, and the feed composition is as follows: 50% of tetrahydrofuran and 50% of water. The extractant pyrrolidone feed rate is 6 kg/h. The operation pressure of the extractive distillation column T1 is 0.40atm, the reflux ratio is 2.5, the number of the tower plates is 50, the mixed liquid feeding plate is 48, and the extractant feeding plate is 19. 502 kg/h is taken out from the top of the tower. The purity of tetrahydrofuran extracted from the top of the tower is 99.53 percent; the tetrahydrofuran content in the water extracted from the tower bottom is 676ppm, and the pyrrolidone content is 0.73%. The yield of tetrahydrofuran was 99.93%.
Example 3
The tetrahydrofuran-water mixed solution has the feed flow of 1000kg/h,25 ℃, and the feed composition is as follows: tetrahydrofuran 30% and water 70%. The extractant pyrrolidone feed flow rate is 5 kg/h. The operation pressure of the extractive distillation column T1 is 0.30atm, the reflux ratio is 5, the number of plates is 45, the mixed liquid feeding plate is 44, and the extractant feeding plate is the 17 th plate. 300 kg/h is extracted from the top of the tower. The purity of tetrahydrofuran extracted from the tower top is 99.92 percent; the tetrahydrofuran content in the water extracted from the tower bottom is 300ppm, and the pyrrolidone content is 0.67%. The yield of tetrahydrofuran was 99.92%.
Example 4
The feeding flow of the tetrahydrofuran-water mixed liquid is 1000kg/h, the temperature is 25 ℃, and the feeding composition is as follows: 80% of tetrahydrofuran and 20% of water. The extractant pyrrolidone feed rate is 7 kg/h. The operation pressure of the extractive distillation tower T1 is 0.70atm, the reflux ratio is 3.5, the number of the tower plates is 50, the mixed liquid feeding plate is 49, and the extractant feeding plate is 19. The top of the tower is taken out of 802 kg/h. The purity of tetrahydrofuran extracted from the tower top is 99.70 percent; the tetrahydrofuran content in the water extracted from the tower bottom is 473 ppm, and the pyrrolidone content is 2.40%. The yield of tetrahydrofuran was 99.98%.
The invention is not limited to the above best mode, and other various devices and methods for separating tetrahydrofuran-water mixture by single-column extractive distillation can be obtained by anyone in the light of the present invention. All equivalent changes and modifications made according to the claims of the present invention should be covered by the present invention.
Claims (1)
1. A device for separating tetrahydrofuran-water mixture by single-tower extractive distillation is characterized in that: comprises an extraction rectifying tower, a condenser, a reboiler, a reflux tank and a reflux pump;
an extractant feeding port and a raw material inlet are respectively arranged at the middle upper part and the lower part of the extraction rectifying tower, a gas phase outlet at the top of the extraction rectifying tower is connected with an inlet at the hot end of a condenser, an outlet of the condenser is communicated with a feeding port of a reflux tank, a discharging port of the reflux tank is connected with an inlet of a reflux pump, a discharging port of the reflux pump is communicated with a reflux port of the extraction rectifying tower, a tower kettle of the extraction rectifying tower is connected with an inlet of a reboiler, and an outlet of the reboiler is communicated with the upper part of the tower kettle; the theoretical plate number of the extraction and rectification tower is 25 to 40, the feed inlet of the extractant is positioned at 3~1/2 of the tower 1/5363, and the raw material inlet is positioned at 5~5/6 of the tower; the method for the device for separating the tetrahydrofuran-water mixture by single-tower extractive distillation comprises the following steps:
(1) The extractant pyrrolidone is fed into the extraction and rectification tower from an extractant feed inlet at the upper part of the middle part, and a mixture of tetrahydrofuran and water as a raw material is preheated and then fed into a raw material inlet at the lower part of the extraction and rectification tower to be in countercurrent contact with the extractant fed from the upper part of the extraction and rectification tower, so that multi-stage vapor-liquid mass transfer is carried out;
(2) Tetrahydrofuran steam at the top of the extraction rectifying tower is subjected to phase change through a condenser to form liquid-phase condensate;
(3) The liquid phase from the condenser is sent into a reflux tank, after the material discharged from the reflux tank is pressurized by a reflux pump, one part of the material is returned to the extraction and rectification tower as reflux, and the other part of the material is extracted as a tetrahydrofuran product;
(4) Feeding a part of the material discharged from the bottom of the extraction and rectification tower into a reboiler, returning the part of the material to the extraction and rectification tower after the part of the material is vaporized under the heating action of steam, and directly discharging the other part of the material discharged from the bottom of the extraction and rectification tower as wastewater;
the operating pressure of the extraction rectifying tower is 0.4 to 0.8 atm, and the reflux ratio is 0.5 to 3.5;
the feeding mass flow ratio of the extracting agent to the tetrahydrofuran-water mixed solution is 0.001 to 0.01;
and (3) after separation, the tetrahydrofuran content in the tetrahydrofuran-water mixture is 30 to 85 percent.
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| CN115487527B (en) * | 2022-09-30 | 2024-01-16 | 东华工程科技股份有限公司 | Single-tower device for rectifying and separating tetrahydrofuran and water mixture |
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| CN103193579A (en) * | 2013-03-20 | 2013-07-10 | 浙江大学 | Method for separating mixture of normal hexane and tetrahydrofuran through extractive distillation |
| CN105968073A (en) * | 2016-07-10 | 2016-09-28 | 青岛科技大学 | Method for recycling tetrahydrofuran in tetrahydrofuran-methanol-water by single-tower extractive distillation |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103193579A (en) * | 2013-03-20 | 2013-07-10 | 浙江大学 | Method for separating mixture of normal hexane and tetrahydrofuran through extractive distillation |
| CN105968073A (en) * | 2016-07-10 | 2016-09-28 | 青岛科技大学 | Method for recycling tetrahydrofuran in tetrahydrofuran-methanol-water by single-tower extractive distillation |
Non-Patent Citations (1)
| Title |
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| 萃取精馏分离四氢呋喃－水共沸物的模拟研究;马春蕾等;《现代化工》;20160930;第36卷(第9期);183左栏第2段至185右栏第2段 * |
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