阅读说明：本技术 萃取精馏分离丙酮-正庚烷混合物的装置及方法 (Device and method for separating acetone-n-heptane mixture by extractive distillation ) 是由 张义 史普赟 陈晓荣 齐运峰 于 2020-11-03 设计创作，主要内容包括：本发明公开了一种萃取精馏分离丙酮-正庚烷混合物的装置及方法,属于萃取精馏分离技术领域。其技术方案为：包括萃取精馏塔,萃取精馏塔的塔底连接有再沸器,塔顶连接有第一冷凝器,第一冷凝器的出口与萃取精馏塔的回流入口之间连接有回流罐。本发明具有不用引入共沸剂、产品纯度高、操作简单的优点。(The invention discloses a device and a method for separating an acetone-n-heptane mixture by extractive distillation, belonging to the technical field of extractive distillation separation. The technical scheme is as follows: the device comprises an extraction rectifying tower, wherein a reboiler is connected to the bottom of the extraction rectifying tower, a first condenser is connected to the top of the tower, and a reflux tank is connected between the outlet of the first condenser and the reflux inlet of the extraction rectifying tower. The method has the advantages of no need of introducing an entrainer, high product purity and simple operation.)

1. The device for separating the acetone-n-heptane mixture by extractive distillation is characterized by comprising an extractive distillation tower (1), wherein a reboiler (2) is connected to the bottom of the extractive distillation tower (1), a first condenser (3) is connected to the top of the tower, and a reflux tank (4) is connected between the outlet of the first condenser (3) and the reflux inlet of the extractive distillation tower (1).

2. The apparatus for the extractive distillation separation of an acetone-n-heptane mixture according to claim 1, characterized in that a second condenser (5) is connected between the extractant outlet in the middle and the extractant inlet in the upper part of the extractive distillation column (1).

3. The process for the extractive distillation separation of an acetone-n-heptane mixture using the apparatus according to claim 2, characterized in that it comprises the following steps:

(1) acetone-n-heptane mixture enters from a mixture inlet at the middle lower part of the extractive distillation tower (1), an extracting agent enters from an extracting agent inlet at the upper part of the extractive distillation tower (1), and after the substance at the top of the extractive distillation tower (1) is condensed by a first condenser (3) and stored in a reflux tank (4), one part of the substance is extracted as an acetone product, and the other part of the substance flows back to the extractive distillation tower (1);

the material flow at the bottom of the extraction and rectification tower (1) is a normal heptane product;

(3) the extractant is extracted from an extractant extraction outlet at the middle part of the extraction rectification tower (1), condensed by a second condenser (5), and then converged with the supplemented extractant, and enters the extraction rectification tower (1) from an extractant inlet for recycling.

4. The method of claim 3, wherein the extractant is 1-chlorobutane.

5. The method according to claim 3, wherein the pressure of the extractive distillation column (1) is 0.6-2.2atm and the reflux ratio is 28-35.

6. The method according to claim 3, characterized in that the temperature of the top of the extractive distillation column (1) is 46-58 ℃ and the temperature of the bottom of the column is 90-120 ℃.

Technical Field

The invention relates to the technical field of extractive distillation separation, in particular to a device and a method for separating an acetone-n-heptane mixture by extractive distillation.

Background

Common solvents and organic raw materials in acetone and n-heptane chemical industry have good solubility. The acetone is applied to industries such as explosives, plastics, rubber, fibers, leather, grease, paint spraying and the like, and can also be used as an important raw material for synthesizing substances such as ketene, acetic anhydride, iodoform, polyisoprene rubber, methyl methacrylate, chloroform, epoxy resin and the like. The n-heptane can be used as a standard substance for measuring the octane number to synthesize ethyl acetate, and has important values in the aspects of chemical raw materials, industrial solvents, anesthetics, energy sources and the like. In order to reduce environmental pollution and production cost, it is important to select a proper method to separate the mixed solution of acetone and n-heptane from organic and pharmaceutical wastewater.

However, acetone and n-heptane mixtures can form binary azeotropes at 55.82 ℃ with compositions containing acetone 0.8802 (mass fraction), which is difficult to separate by common distillation methods. The common method for the binary azeotrope is extractive distillation, and the key technology is the selection of an extracting agent and a separation method. The commonly used traditional extracting agents are ethylene glycol, DMF, DMSO, butyl butyrate, butyl propionate and the like, and the boiling point of the extracting agents is high, so that the heat load of a reboiler of the rectifying tower is too high, the operation cost is increased, and the new concept of energy saving and emission reduction in industry is violated. In addition, the separation sequence corresponding to the extractant is usually conventional extractive distillation, and the defects of the conventional extractive distillation are that the heat load of a distillation tower is too high, the energy consumption is high, and the operation cost and the equipment cost are increased.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, provides a device and a method for separating an acetone-n-heptane mixture by extractive distillation, and has the advantages of no need of introducing an entrainer, high product purity, simple operation, low energy consumption, low operation cost and industrial production.

In a first aspect, the invention provides a device for separating an acetone-n-heptane mixture by extractive distillation, which comprises an extractive distillation tower, wherein a reboiler is connected to the bottom of the extractive distillation tower, a first condenser is connected to the top of the extractive distillation tower, and a reflux tank is connected between an outlet of the first condenser and a reflux inlet of the extractive distillation tower.

Preferably, a second condenser is connected between an extractant extraction outlet in the middle of the extractive distillation column and an extractant inlet in the upper part of the extractive distillation column.

In a second aspect, the invention provides a method for separating an acetone-n-heptane mixture by extractive distillation by using the device, which comprises the following steps:

(1) the acetone-n-heptane mixture enters from a mixture inlet at the middle lower part of the extractive distillation tower, the extracting agent enters from an extracting agent inlet at the upper part of the extractive distillation tower, and after the material flow at the top of the extractive distillation tower is condensed by a first condenser and stored in a reflux tank, one part of the material flow is extracted as an acetone product, and the other part of the material flow flows back to the extractive distillation tower;

(2) the material flow at the bottom of the extraction rectifying tower is an n-heptane product;

(3) the extractant is extracted from an extractant extraction outlet at the middle part of the extraction and rectification tower, condensed by a second condenser, converged with the supplemented extractant, and enters the extraction and rectification tower from an extractant inlet for recycling.

Preferably, the extractant is 1-chlorobutane.

Preferably, the pressure of the extractive distillation column is 0.6-2.2atm, and the reflux ratio is 28-35, wherein the purity of the separated acetone and n-heptane products is higher.

Preferably, the temperature of the top of the extractive distillation column is 46-58 ℃ and the temperature of the bottom of the extractive distillation column is 90-120 ℃.

Compared with the prior art, the invention has the following beneficial effects:

the extraction agent 1-chlorobutane adopted by the invention has a boiling point between that of acetone and normal heptane and a relatively low boiling point, and the 1-chlorobutane is used as the intermediate boiling point extraction agent to carry out the extraction and rectification operation of the acetone-normal heptane mixture, so that the heat load of a reboiler of a rectification tower is reduced while the separation effect is achieved. Meanwhile, a separation sequence of side-stream extractive distillation is adopted, an extracting agent is extracted from the side stream in an extractive distillation tower and circulated into the extractive distillation tower, and the extractive distillation and the solvent recovery are completed in one tower, so that a solvent recovery tower is saved, the equipment cost of the distillation tower is reduced while the heat load is reduced, and the purpose of separating binary azeotrope by single-tower extractive distillation is realized on the basis of energy conservation and emission reduction. And the extractant is directly recycled, so that the cost is reduced, and the pollution to the environment is reduced. The purity of the acetone and n-heptane products separated by the device and the method is more than 0.995, and the purity of the 1-chlorobutane extracted from the middle part of the extraction rectifying tower is more than 0.999.

Drawings

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

In the figure, 1-extractive distillation column, 2-reboiler, 3-first condenser, 4-reflux tank, 5-second condenser.

Detailed Description

As shown in fig. 1, the present embodiment provides an apparatus for separating an acetone-n-heptane mixture by extractive distillation, which includes an extractive distillation column 1, a reboiler 2 connected to the bottom of the extractive distillation column 1, a first condenser 3 connected to the top of the extractive distillation column, and a reflux tank 4 connected between an outlet of the first condenser 3 and a reflux inlet of the extractive distillation column 1. And a second condenser 5 is connected between an extractant extraction outlet in the middle of the extraction rectifying tower 1 and an extractant inlet in the upper part. Wherein the pressure of the extraction rectifying tower 1 is 0.6-2.2atm, and the reflux ratio is 28-35; the temperature of the top of the extraction rectifying tower 1 is 46-58 ℃, and the temperature of the bottom of the extraction rectifying tower 1 is 90-120 ℃.

The method for separating the acetone-n-heptane mixture by extractive distillation by using the device comprises the following steps:

(1) acetone-n-heptane mixture enters from a mixture inlet at the middle lower part of the extractive distillation tower 1, a middle boiling point extractant 1-chlorobutane enters from an extractant inlet at the upper part of the extractive distillation tower 1, part of material flow at the top of the extractive distillation tower 1 is extracted as an acetone product after being condensed by a first condenser 3 and stored in a reflux tank 4, and the other part of the material flow returns to the extractive distillation tower 1;

(2) the material flow at the bottom of the extraction rectifying tower 1 is a normal heptane product;

(3) the extractant is extracted from an extractant extraction outlet at the middle part of the extraction rectification tower 1, condensed by a second condenser 5, converged with the supplemented extractant, and enters the extraction rectification tower 1 from an extractant inlet for recycling.

Example 1

The extractive distillation column of this example had 65 theoretical plates, the extractant 1-chlorobutane was fed from the 25 th plate at a flow rate of 1500kg/h, and a mixture of acetone and n-heptane (n-heptane to acetone in a molar ratio of 0.5: 0.5) was fed from the 54 th plate at a flow rate of 5000 kg/h. The extractive distillation tower is operated under normal pressure, the reflux ratio is 25.29, the extraction amount at the top of the tower is 2512.56kg/h, and acetone products with the mass fraction not less than 0.995 are obtained at the top of the tower. The extraction amount at the top of the tower is 2512.54kg/h, and the n-heptane product with the mass fraction not less than 0.995 is obtained at the bottom of the tower. Extracting agent 1-chlorobutane from the 29 th plate, wherein the extraction amount is 1476.36kg/h, and the mass fraction is 0.999.

Example 2

The extractive distillation column of this example had 60 theoretical plates, and the extractant 1-chlorobutane was fed from the 22 th plate at a flow rate of 2800kg/h, and a mixture of acetone and n-heptane (molar ratio of n-heptane to acetone 0.4: 0.6) was fed from the 51 th plate at a flow rate of 5000 kg/h. The extractive distillation tower is operated under normal pressure, the reflux ratio is 28.18, the extraction amount at the top of the tower is 3015.08kg/h, and acetone products with the mass fraction not less than 0.995 are obtained at the top of the tower. The extraction amount at the top of the tower is 2009.99kg/h, and the n-heptane product with the mass fraction not less than 0.995 is obtained at the bottom of the tower. Extracting agent 1-chlorobutane from the 25 th plate, wherein the extraction amount is 2777.71kg/h, and the mass fraction is 0.999.

Example 3

The extractive distillation column of this example had 63 theoretical plates, the extractant 1-chlorobutane was fed from the 25 th plate at a flow rate of 2500kg/h, and a mixture of acetone and n-heptane (n-heptane to acetone in a molar ratio of 0.3: 0.7) was fed from the 53 th plate at a flow rate of 5000 kg/h. The extractive distillation tower is operated under normal pressure, the reflux ratio is 30.21, the extraction amount at the top of the tower is 3517.59kg/h, and acetone products with the mass fraction not less than 0.995 are obtained at the top of the tower. The extraction amount at the top of the tower is 1507.51kg/h, and the n-heptane product with the mass fraction not less than 0.995 is obtained at the bottom of the tower. Extracting agent 1-chlorobutane from the 29 th plate, wherein the extraction amount is 2477.38kg/h, and the mass fraction is 0.999.

Example 4

The extractive distillation column of this example had 68 theoretical plates, the extractant 1-chlorobutane was fed from the 30 th plate at a flow rate of 3500kg/h, and a mixture of acetone and n-heptane (n-heptane to acetone molar ratio 0.1198: 0.8802) was fed from the 60 th plate at a flow rate of 5000 kg/h. The extractive distillation tower is operated under normal pressure, the reflux ratio is 30.15, the extraction amount at the top of the tower is 3015.08kg/h, and an acetone product with the mass fraction not less than 0.995 is obtained at the top of the tower. The extraction amount at the top of the tower is 2009.99kg/h, and the n-heptane product with the mass fraction not less than 0.995 is obtained at the bottom of the tower. Extracting agent 1-chlorobutane from the 25 th plate, wherein the extraction amount is 2777.71kg/h, and the mass fraction is 0.999.

Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.