阅读说明：本技术 一种萃取精馏分离水-乙醇-异丙醇混合物的方法 (Method for separating water-ethanol-isopropanol mixture by extractive distillation ) 是由 章连众 郝晓宇 于 2020-06-28 设计创作，主要内容包括：一种萃取精馏分离水-乙醇-异丙醇混合物的方法,所述方法包括：以氯化胆碱与乙二醇物质的量之比1：2组成的低共熔溶剂作为萃取剂,进行水-乙醇-异丙醇混合物的萃取精馏分离；本发明以氯化胆碱和乙二醇组成的低共熔溶剂为萃取剂,能显著破坏乙醇-水、异丙醇-水共沸体系,最终得到高纯度的乙醇、异丙醇产品；本发明方法工艺简单,易于操作,使用的萃取剂具有无毒、无腐蚀、无污染、易回收、可循环使用的特点,能有效降低生产成本,采用本发明的技术方法得到的乙醇、异丙醇纯度和收率均大于99％。(A method for extractive distillation separation of a water-ethanol-isopropanol mixture, the method comprising: in a ratio of the amounts of choline chloride and glycol species of 1: 2, taking the eutectic solvent as an extractant to perform extraction, rectification and separation on a water-ethanol-isopropanol mixture; according to the invention, a eutectic solvent composed of choline chloride and ethylene glycol is used as an extractant, so that an ethanol-water and isopropanol-water azeotropic system can be remarkably destroyed, and high-purity ethanol and isopropanol products are finally obtained; the method has simple process and easy operation, the used extracting agent has the characteristics of no toxicity, no corrosion, no pollution, easy recovery and recycling, the production cost can be effectively reduced, and the purity and the yield of the ethanol and the isopropanol obtained by the technical method are both more than 99 percent.)

1. A method for separating a water-ethanol-isopropanol mixture by extractive distillation, which is characterized by comprising the following steps: in a ratio of the amounts of choline chloride and glycol species of 1: 2 as extractant to extract, rectify and separate water-alcohol-isopropanol mixture.

2. The process for the extractive distillation separation of a water-ethanol-isopropanol mixture according to claim 1, comprising the steps of:

(1) adding a water-ethanol-isopropanol mixture and an extracting agent into an extraction rectifying tower, extracting a light component containing ethanol-isopropanol from the top of the extraction rectifying tower, and extracting a heavy component containing water and the extracting agent from a tower kettle;

the number of tower plates of the extractive distillation tower is 30-50, the operation condition is normal pressure, the solvent ratio is 0.5-5.0, the reflux ratio is 0.5-3.0, the temperature of the top of the tower is 80-82 ℃, and the temperature of the bottom of the tower is 130-185 ℃;

the water-ethanol-isopropanol mixture enters the extractive distillation tower from the 15 th to 40 th tower plates of the extractive distillation tower, and the extractant enters the extractive distillation tower from the 3 rd to 10 th tower plates;

(2) introducing the light component containing ethanol-isopropanol obtained in the step (1) into an ethanol tower, extracting ethanol from the top of the ethanol tower, and extracting isopropanol from the bottom of the ethanol tower;

the number of the tower plates of the ethanol tower is 80-100, the operation condition is normal pressure, the reflux ratio is 15-20, the temperature of the top of the tower is 75-80 ℃, and the temperature of the bottom of the tower is 80-85 ℃;

the light component containing ethanol-isopropanol enters the ethanol tower from the 40 th-60 th tower plate of the ethanol tower;

(3) introducing the heavy components containing water and the extractant in the step (1) into a solvent recovery tower, extracting water from the top of the solvent recovery tower, extracting the extractant from the bottom of the tower, and introducing the obtained extractant into an extraction rectification tower for recycling;

the number of tower plates of the solvent recovery tower is 10-15, the operation condition is normal pressure, the reflux ratio is 0.3-3, the temperature of the top of the tower is 85-97 ℃, and the temperature of a tower kettle is 215-220 ℃;

and the heavy components containing water and the extracting agent enter the solvent recovery tower from the 7 th to 12 th tower plates of the solvent recovery tower.

Technical Field

The invention relates to a method for separating a water-ethanol-isopropanol mixture, belonging to the technical field of separation of alcohol-water solution.

Background

In the chemical production of heterocyclic compound preparation, medicine raw material synthesis, traditional Chinese medicine component extraction and the like, a mixture of ethanol and isopropanol is often used as a reaction medium and an extracting agent, and other impurities, particularly water, are inevitably introduced in the use process, so that a large amount of alcohol-water solution is generated. In order to reduce the production cost and protect the environment, ethanol and isopropanol need to be separated and recovered from the alcohol-water solution.

The boiling point difference of the ethanol and the isopropanol is small, the ethanol and the isopropanol are azeotropic with water, and the azeotropic points are very close. Ethanol and water were azeotroped at 78.2 ℃ with an azeotropic composition of 95.6% (mass fraction, the same applies hereinafter) ethanol and 4.4% water. Isopropanol azeotropes with water at 80.3 ℃ and the azeotropic composition is 87.4% isopropanol and 12.6% water. For azeotropic system and near-azeotropic system, extractive distillation is generally used industrially for separation, and therefore selection of an extraction agent is a major issue.

The eutectic solvent is considered as a novel ionic liquid and consists of ammonium salt and a complexing agent, wherein the complexing agent can be urea, carboxylic acid, glycol and the like. The eutectic solvent has similar physical and chemical properties to the traditional ionic liquid, has the characteristics of simple synthesis, environmental friendliness and the like, and is widely applied to the fields of electrochemistry, catalysis, organic synthesis, dissolution, extraction and material chemistry. As a novel green solvent, the eutectic solvent has the advantages of simple preparation, low price, no toxicity, degradability, low saturated steam pressure, strong designability and the like, can effectively reduce equipment investment, simplify separation process and reduce energy consumption in the application of extraction and rectification, and has great application prospect.

Disclosure of Invention

The invention aims to provide a method for extracting, rectifying and separating a water-ethanol-isopropanol mixture. The method uses choline chloride-ethylene glycol to react in a ratio of 1: 2, the process is simple, the operation is easy, the energy consumption is low, the extractant is non-corrosive and easy to recover, the extractant can be recycled, the production cost can be effectively reduced, and the purity of the separated ethanol and isopropanol products is high.

The technical scheme of the invention is as follows:

a method for extractive distillation separation of a water-ethanol-isopropanol mixture, the method comprising: in a ratio of the amounts of choline chloride and glycol species of 1: 2 as extractant to extract, rectify and separate water-alcohol-isopropanol mixture.

Specifically, the method for separating the water-ethanol-isopropanol mixture by extractive distillation comprises the following steps:

(1) adding a water-ethanol-isopropanol mixture and an extracting agent into an extraction rectifying tower, extracting a light component containing ethanol-isopropanol from the top of the extraction rectifying tower, and extracting a heavy component containing water and the extracting agent from a tower kettle;

the number of the tower plates of the extractive distillation tower is 30-50, the operation condition is normal pressure (101.3kPa), the solvent ratio is 0.5-5.0, the reflux ratio is 0.5-3.0, the temperature of the top of the tower is 80-82 ℃, and the temperature of the bottom of the tower is 130-185 ℃;

the water-ethanol-isopropanol mixture enters the extractive distillation tower from the 15 th to 40 th tower plates of the extractive distillation tower, and the extractant enters the extractive distillation tower from the 3 rd to 10 th tower plates;

(2) introducing the light component containing ethanol-isopropanol obtained in the step (1) into an ethanol tower, extracting ethanol from the top of the ethanol tower, and extracting isopropanol from the bottom of the ethanol tower;

the number of the tower plates of the ethanol tower is 80-100, the operation condition is normal pressure (101.3kPa), the reflux ratio is 15-20, the temperature of the top of the tower is 75-80 ℃, and the temperature of a tower kettle is 80-85 ℃;

the light component containing ethanol-isopropanol enters the ethanol tower from the 40 th-60 th tower plate of the ethanol tower;

(3) introducing the heavy components containing water and the extractant in the step (1) into a solvent recovery tower, extracting water from the top of the solvent recovery tower, extracting the extractant from the bottom of the tower, and introducing the obtained extractant into an extraction rectification tower for recycling;

the number of tower plates of the solvent recovery tower is 10-15, the operation condition is normal pressure (101.3kPa), the reflux ratio is 0.3-3, the temperature of the top of the tower is 85-97 ℃, and the temperature of the bottom of the tower is 215-220 ℃;

and the heavy components containing water and the extracting agent enter the solvent recovery tower from the 7 th to 12 th tower plates of the solvent recovery tower.

The invention has the advantages that:

the invention uses choline chloride and ethylene glycol to react in a ratio of 1: 2 is an extracting agent, can obviously destroy an ethanol-water and isopropanol-water azeotropic system, and finally obtain high-purity ethanol and isopropanol products. The method has simple process and easy operation, and the used extracting agent has the characteristics of no toxicity, no corrosion, no pollution, easy recovery and recycling, and can effectively reduce the production cost. The purity and yield of the ethanol and the isopropanol obtained by the technical method are both more than 99 percent.

Drawings

FIG. 1 is a schematic diagram of the apparatus and process of the present invention.

Detailed Description

The invention will be further described by means of specific embodiments with reference to the attached drawings, but the scope of the invention is not limited thereto.

The apparatus for carrying out the process of the invention, as shown in FIG. 1, comprises: the device comprises an extraction rectifying tower, an ethanol tower and a solvent recovery tower, wherein the top of each tower is provided with a condenser, the bottom of each tower is provided with a reboiler, the extraction rectifying tower is provided with a raw material feeding port and an extractant feeding port, the top of the extraction rectifying tower is connected with the ethanol tower, the bottom of the extraction rectifying tower is connected with the solvent recovery tower, and the bottom of the solvent recovery tower is connected with the extractant feeding port of the extraction rectifying tower.

According to the scheme shown in the figure 1, a water-ethanol-isopropanol mixture enters an extractive distillation tower from a position of 15 th to 40 th theoretical plates of the extractive distillation tower with the number of 30 to 50 theoretical plates by adopting continuous operation, and an extracting agent enters the extractive distillation tower from a position of 3 rd to 10 th theoretical plates; extracting and rectifying the ethanol-isopropanol mixed solution, extracting the ethanol-isopropanol mixed solution from the tower top, feeding the ethanol-isopropanol mixed solution into an ethanol tower, separating the ethanol and the isopropanol, extracting the ethanol from the tower top of the ethanol tower, and extracting the isopropanol from a tower kettle of the ethanol tower; the mixed solution of the extractant and the water is extracted from the bottom of the extraction rectifying tower and then enters a solvent recovery tower, after separation, the water is extracted from the top of the solvent recovery tower, and the extractant is extracted from the bottom of the extraction rectifying tower and then continuously enters the extraction rectifying tower through an extractant feed port of the extraction rectifying tower for recycling.