阅读说明：本技术 一种反应精馏联合侧线萃取精馏分离四氢呋喃-乙醇-水三元共沸体系的方法 (Method for separating tetrahydrofuran-ethanol-water ternary azeotropic system by combining reactive distillation with side line extractive distillation ) 是由 申威峰 杨傲 于 2019-10-28 设计创作，主要内容包括：本发明公开了一种反应精馏联合侧线萃取精馏分离三元共沸体系的方法,采用反应物环氧乙烷与三元共沸物中的水在反应精馏塔C1内进行反应生成副产物乙二醇,剩余的四氢呋喃和乙醇二元共沸体系采用DMSO为萃取剂在萃取精馏塔C2内发生萃取作用,在塔顶得到高纯度的四氢呋喃产品,塔底为高纯度DMSO液体送入冷却器冷却循环利用,侧线采出的乙醇和DMSO混合液送入溶剂回收塔C3的中部,在C3的顶部得到高纯度的乙醇产品,塔釜得到高纯度的DMSO经过冷凝器冷却后与补加的DMSO混合后送入C2塔的上部循环使用,减小萃取剂的用量。本发明通过反应精馏联合侧线萃取精馏的方法解决了三元多共沸体系的分离难题,从而有效的解决了传统变压精馏能耗高和CO<Sub>2</Sub>排放大等缺点。(The invention discloses a method for separating a ternary azeotropic system by combining reactive distillation and side line extractive distillation, which comprises the steps of adopting reactant ethylene oxide and water in ternary azeotrope to react in a reactive distillation tower C1 to generate a byproduct ethylene glycol, adopting DMSO as an extracting agent to perform extraction action in an extractive distillation tower C2 for the residual binary azeotropic system of tetrahydrofuran and ethanol, obtaining a high-purity tetrahydrofuran product at the tower top, and adopting a high-purity DMSO liquid at the tower bottomThe mixture of the ethanol and the DMSO collected from the side line is sent to the middle part of a solvent recovery tower C3, a high-purity ethanol product is obtained at the top of C3, the high-purity DMSO obtained at the tower bottom is cooled by a condenser, mixed with the supplemented DMSO and sent to the upper part of a C2 tower for recycling, and the dosage of the extractant is reduced. The method solves the separation problem of a ternary multi-azeotropic system by combining reactive distillation and side line extractive distillation, thereby effectively solving the problems of high energy consumption and CO consumption of the traditional pressure swing distillation 2 Row enlargement and the like.)

1. A method for separating tetrahydrofuran, ethanol and water ternary azeotropic system by combining reactive distillation and side line extractive distillation is characterized in that: a rectifying section, a reaction section and a stripping section are arranged in the reactive rectifying tower C1 from top to bottom; the side extractive distillation column C2 is internally provided with a rectifying section, an extracting section and a stripping section from top to bottom in sequence:

the water component in the ternary mixture is firstly added with ethylene oxide and water to react in a reaction rectifying tower C1 to remove water, a byproduct ethylene glycol generated after the reaction is extracted from the bottom of the reaction rectifying tower C1, tetrahydrofuran and ethanol steam at the tower top enters a tetrahydrofuran and ethanol condenser to be condensed and then enters a tetrahydrofuran and ethanol reflux tank, one part of the tetrahydrofuran and ethanol steam flows back to the upper part in the reaction rectifying tower C1, and the other part of the tetrahydrofuran and ethanol steam is directly extracted;

taking dimethyl sulfoxide (DMSO) as an extractant, collecting a mixed solution of tetrahydrofuran and ethanol to be separated from the upper part of a reactive distillation column C1, introducing the mixed solution into the middle-lower part of a lateral line extractive distillation column C2, and carrying out countercurrent contact with the extractant introduced from an upper extractant inlet to perform extraction;

tetrahydrofuran is extracted from the top of the side extractive distillation column C2, condensed by a tetrahydrofuran condenser and then enters a tetrahydrofuran reflux tank, part of the tetrahydrofuran is refluxed to the side extractive distillation column C2 from the upper part of the side extractive distillation column C2 to form gas-liquid mass transfer and heat transfer, and the other part of the tetrahydrofuran is extracted;

cooling and recycling the high-purity DMSO extracted from the liquid extraction outlet at the bottom of the side extraction rectifying tower C2 through a cooler;

and a part of mixed solution of tetrahydrofuran and DMSO extracted from the middle part of the side extraction rectifying tower C2 enters the middle part of the solvent recovery tower C3, ethanol and dimethyl sulfoxide are separated and purified in the solvent recovery tower C3, ethanol steam enters the ethanol condenser for condensation and then enters the ethanol reflux tank, a part of ethanol reflows to the upper part of the solvent recovery tower C3 to form gas-liquid mass transfer and heat transfer, and the other part of ethanol is extracted.

2. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the feeding molar ratio of reactants to tetrahydrofuran, ethanol and water is 0.3-0.5, and the feeding temperature is 30-35 ℃; the feeding molar ratio of the extracting agent to the mixed solution of tetrahydrofuran and ethanol is 1.2-0.8, and the feeding temperature is 50 ℃.

3. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the theoretical plate number of the reaction rectifying tower C1 is 25-30, the reactant inlet is positioned at 3-6 plate, the mixed liquid inlet is positioned at 8-12 plate, and the liquid holdup between reaction sections is 0.08-0.12m³The tower top temperature is 77-79 ℃, and the tower bottom temperature is 196-197 ℃.

4. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the feeding temperature of the mixed solution of tetrahydrofuran, ethanol and water is 40-60 ℃.

5. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the number of theoretical plates of the side extraction rectifying tower C2 is 25-30, an extractant feeding hole is positioned at the 3 rd-6 th tower plate, a tetrahydrofuran and ethanol mixed solution inlet is positioned at the 8 th-12 th tower plate, a side extraction hole of the tetrahydrofuran and DMSO mixed solution is positioned at the 18 th-22 th tower plate, the feeding temperature of the extractant DMSO is 40-60 ℃, and the flow rate is 50-80 kmol/h.

6. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the theoretical plate number of the solvent recovery tower C3 is 23-27, and the inlet of the mixed solution of ethanol and DMSO is positioned at the 7 th-12 th plate.

7. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the operating pressure of the reactive distillation column C1, the side-draw extractive distillation column C2 and the solvent recovery column C3 is normal pressure.

8. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and side line extractive distillation according to claim 1, which is characterized in that: the reflux ratio of the reactive distillation column C1 is 0.7-1.2, the reflux ratio of the side extraction distillation column C2 is 0.2-0.8, and the reflux ratio of the solvent recovery column C3 is 0.1-0.5.

Technical Field

The invention relates to a method for separating a tetrahydrofuran-ethanol-water ternary azeotropic system by combining reactive distillation with side line extractive distillation, belonging to the field of distillation and purification.

Background

Tetrahydrofuran and ethanol are both important chemical raw materials.Tetrahydrofuran is a colorless and water-miscible organic liquid. The chemical formula of such cyclic ethers can be written as (CH)₂)₄And O. Its main use is as a precursor of high molecular polymers. The ethanol is a flammable and volatile colorless transparent liquid at normal temperature and normal pressure, has low toxicity, and can not be directly drunk as a pure liquid; has special fragrance and slight irritation; slightly sweet and accompanied by pungent and spicy taste. Inflammable, its steam can form explosive mixture with air, and it can be dissolved in water in any ratio. Is miscible with chloroform, diethyl ether, methanol, acetone and most other organic solvents, and has a relative density (d15.56) of 0.816. The ethanol has wide application range, and can be used for preparing acetic acid, beverages, essence, dye, fuel and the like. In medical treatment, ethanol with the volume fraction of 70-75% is also commonly used as a disinfectant and the like, and has wide application in national defense chemical industry, medical treatment and health, food industry, industrial and agricultural production.

In the production process of the actual chemical industry and the pharmaceutical industry, aqueous solution of tetrahydrofuran and ethanol is often formed. If the waste water is directly discharged, environmental pollution and resource waste are caused, so that the waste water has a great prospect of recycling the waste water. Under normal pressure, tetrahydrofuran, ethanol and water form azeotropy in pairs, and the tetrahydrofuran, the ethanol and the water cannot be separated by adopting common rectification and are difficult to separate. And the traditional rectification has high energy consumption, low energy utilization rate and large carbon dioxide emission, so special rectification is required. How to separate the mixed solution of tetrahydrofuran, ethanol and water becomes a problem which needs to be solved urgently.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a method for separating a tetrahydrofuran-ethanol-water ternary azeotropic system by combining reactive distillation with side line extractive distillation, which has the advantages of low energy consumption, high product purity and high environmental protection.

In order to achieve the first object, the technical scheme of the invention is as follows: a method for separating a tetrahydrofuran-ethanol-water ternary azeotropic system by combining reactive distillation and side line extractive distillation is characterized by comprising the following steps of: the water component in the ternary mixture is firstly added with ethylene oxide and water to react in a reaction rectifying tower C1 to remove water, a byproduct ethylene glycol generated after the reaction is extracted from the bottom of the reaction rectifying tower C1, tetrahydrofuran and ethanol steam at the tower top enters a tetrahydrofuran and ethanol condenser to be condensed and then enters a tetrahydrofuran and ethanol reflux tank, one part of the tetrahydrofuran and ethanol steam flows back to the upper part in the reaction rectifying tower C1, and the other part of the tetrahydrofuran and ethanol steam is directly extracted;

taking dimethyl sulfoxide as an extractant, collecting a mixed solution of tetrahydrofuran and ethanol to be separated from the upper part of a reactive distillation column C1, feeding the mixed solution into the middle-lower part of a side extractive distillation column C2, and carrying out countercurrent contact with the extractant fed from an upper extractant inlet to perform extraction;

tetrahydrofuran is extracted from the top of the side extractive distillation column C2, condensed by a tetrahydrofuran condenser and then enters a tetrahydrofuran reflux tank, part of the tetrahydrofuran is refluxed to the side extractive distillation column C2 from the upper part of the extractive distillation column C2 to form gas-liquid mass transfer and heat transfer, and the other part of the tetrahydrofuran is extracted;

cooling and recycling the high-purity DMSO extracted from the liquid extraction outlet at the bottom of the side extraction rectifying tower C2 through a cooler;

the method comprises the following steps that part of mixed solution of tetrahydrofuran and DMSO extracted from the middle part of a side extraction rectifying tower C2 enters the middle part of a solvent recovery tower C3, ethanol and dimethyl sulfoxide are separated and purified in a solvent recovery tower C3, ethanol steam enters an ethanol condenser for condensation and then enters an ethanol reflux tank, part of ethanol reflows to the upper part of the solvent recovery tower C3 to form gas-liquid mass transfer and heat transfer, and the other part of ethanol is extracted; according to the invention, the water component in the ternary azeotropic mixture is removed by utilizing the efficient reaction of ethylene oxide and water, the azeotropic characteristic can be broken by adding a certain amount of dimethyl sulfoxide (DMSO), which is an extracting agent, to different molecular acting forces of tetrahydrofuran and water, and the separation and purification of a complex ternary azeotropic system are realized by adopting reactive distillation and extractive distillation. The method can effectively reduce heat load, ensure product quality, and reduce production cost and CO₂And (4) discharging. The purity of the separated tetrahydrofuran product is more than 99.4%, the purity of ethanol is more than 99.4%, the purity of the by-product glycol is more than 99.9%, and the purity of the circulating extractant DMSO is more than 99.99%.

In the scheme, the method comprises the following steps: the feeding molar ratio of the reactant to the mixed solution of tetrahydrofuran, ethanol and water is 0.3-0.5; the feeding molar ratio of the extracting agent to the mixed liquid of tetrahydrofuran, ethanol and water is 1.1-1.

As a preferable aspect of the above-described aspect: the theoretical plate number of the reaction rectifying tower C1 is 27, the reactant inlet is positioned at 4-6 plates, the inlet of the mixed solution of tetrahydrofuran, ethanol and water is positioned at 8-12 plates, the upper part of the reaction section is positioned at 2-3 plates, the lower part of the reaction section is positioned at 14-16 plates, the tower top temperature is 67-68 ℃, the tower bottom temperature is 201-. The side line extractive distillation tower C2 has 28 theoretical plates, the mixed liquid inlet of tetrahydrofuran and ethanol is located at 13-15 tower plates, the extractant inlet is located at 3-5 tower plates, the side line extraction outlet is located at 18-22 tower plates, the tower top temperature is 65-66 ℃, and the tower bottom temperature is 125-126 ℃. The theoretical plate of the solvent recovery tower C3 is 25, the inlet of the mixed solution of ethanol and DMSO is positioned at 8-12 tower plates, the temperature of the top of the tower is 77-79 ℃, and the temperature of the bottom of the tower is 196-197 ℃.

In the scheme, the method comprises the following steps: the feeding temperature of the mixed solution of tetrahydrofuran, ethanol and water is 40-60 ℃; the feed temperature of the reactant ethylene oxide is 30-35 ℃.

In the scheme, the method comprises the following steps: the feed flow of the extractant is 65-75 kmol/h.

In the scheme, the method comprises the following steps: the reactant feeding flow of the reactive distillation column C1 is 30-50 kmol/h; the feeding flow of the mixed liquid of tetrahydrofuran, ethanol and water is 90-110 kmol/h.

In the scheme, the method comprises the following steps: the liquid flow rate of the side line extraction is 45-65 kmol/h.

In the scheme, the method comprises the following steps: the operating pressure of the rectification columns C1, C2 and C3 is normal pressure.

The reflux ratio of the reactive distillation column C1 is 0.7-1.2, the reflux ratio of the side extraction distillation column C2 is 0.2-0.8, and the reflux ratio of the solvent recovery column C3 is 0.1-0.5.

Advantageous effects

Compared with the prior art, the invention mainly has the following gain effects:

(1) the separation method of the invention has reasonable operation, strong practicability and extremely high industrial popularization. The reaction rectifying tower and the extraction rectifying tower related by the invention can effectively reduce the separation difficulty, and the obtained product has high purity.

(2) The energy consumption of the separation process is reduced. Compared with the three-tower pressure swing rectification, the reactive rectification combined extraction rectification device related by the invention can reduce the energy consumption cost by 40-70%.

(3) The process can effectively reduce CO₂Thereby realizing the concept of sustainable green development.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention is further illustrated by the following examples:

the foregoing is a more detailed description of the invention, taken in conjunction with specific preferred embodiments thereof.

As shown in fig. 1

The reaction rectifying tower C1 comprises a rectifying section, a reaction section and a stripping section from top to bottom in sequence, the theoretical plate number of the reaction rectifying tower C1 is 27, a reactant inlet a is positioned at 4-6 tower plates, a mixed liquid inlet b is positioned at 8-12 tower plates, the upper part C of the reaction section is positioned at 2-3 tower plates, and the lower part d of the reaction section is positioned at 14-16 tower plates; the mixed solution of tetrahydrofuran and ethanol extracted from the top of the reactive distillation column C1 is sent to the middle lower part of the side extractive distillation column C2, the inlet f of the mixed solution of tetrahydrofuran and ethanol is positioned at 12-16 tower plates, and the inlet e of the extractant is positioned at 3-5 tower plates; a side draw position port g of the side draw extractive distillation column C2 is positioned at 18 th-22 th tower plates, the mixed solution of ethanol and DMSO extracted from the side draw port g is sent to the middle part of the solvent recovery column C3, and an inlet h of the mixed solution of ethanol and DMSO is positioned at 8 th-12 tower plates.