阅读说明：本技术 一种反应精馏联合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 reactive distillation and 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萃取精馏分离三元共沸体系四氢呋喃、乙醇和水的方法,采用环氧乙烷为反应物与三元共沸混合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,塔底为乙醇和DMSO混合液送入溶剂回收塔C3的中部,在溶剂回收塔的顶部得到高纯度的乙醇产品,塔釜得到高纯度的萃取剂DMSO经过冷凝器冷却后与补加的萃取剂DMSO混合后送入萃取精馏塔的上部循环使用,减小萃取剂的用量。本发明通过反应精馏联合萃取精馏的方法解决了四氢呋喃、乙醇和水三元多共沸体系的分离难题,从而有效的解决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 tetrahydrofuran, ethanol and water of a ternary azeotropic system by combining reactive distillation and extractive distillation, which comprises the steps of adopting ethylene oxide as a reactant and water in a ternary azeotropic mixture to react in a reactive distillation tower C1 to generate a byproduct of ethylene glycol, adopting DMSO as an extractant in a residual tetrahydrofuran and ethanol binary azeotropic system to perform extraction in an extractive distillation tower C2, obtaining a high-purity tetrahydrofuran product at the top of the tower, sending a mixed solution of ethanol and DMSO at the bottom of the tower into the middle part of a solvent recovery tower C3, obtaining a high-purity ethanol product at the top of the solvent recovery tower, obtaining a high-purity extractant DMSO at the bottom of the tower, cooling the high-purity extractant DMSO by a condenser, mixing the high-purity extractant DMSO with a supplemented extractant DMSO, and sending the mixture into the upper part of the extractive distillation tower for recycling, and reducing the dosage. The invention is realized byThe method of rectification combined with extractive rectification solves the separation problem of the ternary multi-azeotropic system of tetrahydrofuran, ethanol and water, thereby effectively solving the problems of high energy consumption and CO consumption of the traditional pressure swing rectification 2 Row enlargement and the like.)

1. A method for separating tetrahydrofuran, ethanol and water ternary azeotropic system by combining reactive distillation and 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 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 as an extractant, extracting 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 an extractive distillation column C2, and performing countercurrent contact with the extractant introduced from an upper extractant inlet to perform extraction;

extracting tetrahydrofuran from the top of the extractive distillation column C2, condensing the tetrahydrofuran by a tetrahydrofuran condenser, then feeding the tetrahydrofuran into a tetrahydrofuran reflux tank, refluxing part of tetrahydrofuran from the upper part of the extractive distillation column C2 into the extractive distillation column C2 to form gas-liquid mass transfer and heat transfer, and extracting the other part of tetrahydrofuran;

the mixed liquid of ethanol and dimethyl sulfoxide extracted from a liquid extraction outlet at the bottom of the extractive distillation column C2 enters the middle part of a solvent recovery column C3, the ethanol and the dimethyl sulfoxide are separated and purified in the solvent recovery column C3, ethanol vapor enters an ethanol condenser for condensation and then enters an ethanol reflux tank, a part of ethanol reflows to the upper part of the solvent recovery column 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 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 extractive distillation according to claim 1, which is characterized in that: the theoretical plate number of the reaction rectifying tower C1 is 25-30, and the reactant inlet positionAt 3-6 tower plates, mixed liquid inlet at 8-12 tower plates, and liquid holdup between reaction sections of 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 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 extractive distillation according to claim 1, which is characterized in that: the number of theoretical plates of the extraction rectifying tower C2 is 25-30, an extractant feeding port 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, the feeding temperature of an 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 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 extractive distillation according to claim 1, which is characterized in that: the operating pressure of the reaction rectifying tower C1, the extraction rectifying tower C2 and the solvent recovery tower C3 is normal pressure.

8. The method for separating the ternary azeotropic system of tetrahydrofuran, ethanol and water by combining reactive distillation and 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 extractive 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 reaction and rectification with extractive rectification, belonging to the field of rectification and purification.

Background

Tetrahydrofuran and ethanol are both important chemical raw materials. Tetrahydrofuran is a colorless, water-miscible, organic liquid that is less viscous at normal temperature and pressure. The chemical formula of such cyclic ethers can be written as (CH)₂)₄And O. It is a commonly used medium polarity aprotic solvent due to its long liquid range. Its main use is as a precursor of high molecular polymerAnd (3) a body. Although tetrahydrofuran has a smell and chemical properties similar to diethyl ether, the anesthetic effect is poor. 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 vapor can form explosive mixture with air, and it can be dissolved in water in any ratio. Can be mixed with chloroform, diethyl ether, methanol, acetone and other organic solvents, and has a relative density 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 actual production process of chemical industry and pharmaceutical industry, a mixed solution of tetrahydrofuran, ethanol and water is often formed. In order to reduce production cost and environmental pollution, it is necessary to recycle it. Under normal pressure, tetrahydrofuran, ethanol and water can form a plurality of azeotropes, 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 reaction rectification and extractive rectification, 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 extractive distillation is characterized by comprising the following steps: 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, extracting 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 an extractive distillation column C2, and performing countercurrent contact with the extractant introduced from an upper extractant inlet to perform extraction;

extracting tetrahydrofuran from the top of the extractive distillation column C2, condensing the tetrahydrofuran by a tetrahydrofuran condenser, then feeding the tetrahydrofuran into a tetrahydrofuran reflux tank, refluxing part of tetrahydrofuran from the upper part of the extractive distillation column C2 into the extractive distillation column C2 to form gas-liquid mass transfer and heat transfer, and extracting the other part of tetrahydrofuran;

the mixed solution of ethanol and dimethyl sulfoxide extracted from a liquid extraction outlet at the bottom of the extractive distillation column C2 enters the middle part of a solvent recovery column C3, the ethanol and the dimethyl sulfoxide are separated and purified in the solvent recovery column C3, ethanol vapor 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 column 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 the heat load, ensure the product quality, and reduce the production cost and the emission of CO 2. The purity of the separated tetrahydrofuran product is more than 99.5 percent, the purity of the ethanol is more than 99.5 percent, the purity of the by-product glycol is more than 99.9 percent, and the purity of the circulating extractant DMSO is more than 99.99 percent.

In the scheme, the method comprises the following steps: the feeding molar ratio of the reactant to the mixed liquid of tetrahydrofuran, ethanol and water is 1.1-1; 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 theoretical plate of the extraction rectifying tower C2 is 28, the inlet of the mixed liquid of tetrahydrofuran and ethanol is positioned at 13-15 tower plates, the inlet of the extracting agent is positioned at 3-5 tower plates, the temperature of the tower top is 65-66 ℃, and the temperature of the tower bottom 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 60-70 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 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 extractive 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 60-80%.

(3) The process can effectively reduce CO₂Thereby realizing sustainable green developmentAnd (5) a concept.

Drawings

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

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

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 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; the mixed solution of ethanol and DMSO extracted from the bottom of the extraction and rectification tower C2 is sent to the middle part of a solvent recovery tower C3, and an inlet g of the mixed solution of ethanol and DMSO is positioned at 8-12 tower plates.