阅读说明：本技术 一种反应精馏耦合萃取精馏制取碳酸二甲酯的装置及工艺 (Device and process for preparing dimethyl carbonate by reactive distillation coupled extraction distillation ) 是由 杨万典 余章学 孙宇赫 王佳兵 刘勇军 李晓翔 陶荣 黄益平 严文荣 沈文彬 于 2020-08-26 设计创作，主要内容包括：本发明提供一种反应精馏耦合萃取精馏制取碳酸二甲酯的装置,所述装置包括：反应精馏塔、萃取精馏塔、萃取剂回收塔和产品塔。本发明还公开了一种反应精馏耦合萃取精馏制取碳酸二甲酯的工艺。本发明利用反应精馏耦合萃取精馏技术,改进现有的酯交换反应工艺路线,提升了碳酸二甲酯生产工艺技术水平。(The invention provides a device for preparing dimethyl carbonate by coupling reaction, rectification and extractive rectification, which comprises: a reaction rectifying tower, an extraction rectifying tower, an extractant recovery tower and a product tower. The invention also discloses a process for preparing dimethyl carbonate by reactive distillation coupled with extractive distillation. The invention utilizes the reactive distillation coupled extractive distillation technology, improves the existing ester exchange reaction process route, and improves the technical level of the dimethyl carbonate production process.)

1. A device for preparing dimethyl carbonate by reactive distillation coupled with extractive distillation is characterized by comprising: a reaction rectifying tower, an extraction rectifying tower, an extractant recovery tower and a product tower;

the top of the reactive distillation column is respectively connected with the upper part of the reactive distillation column through a tower top condenser of the reactive distillation column and connected with the lower part of the extractive distillation column; the bottom of the reactive distillation tower is respectively connected with a feed heat exchanger of the reactive distillation tower and a reboiler at the bottom of the reactive distillation tower;

the top of the extractive distillation column is respectively connected with a condenser at the top of the extractive distillation column and the lower part of the reactive distillation column through a supercharger; the bottom of the extractive distillation column is respectively connected with the lower part of the extractive distillation column through a reboiler at the bottom of the extractive distillation column and is connected with the middle part of an extractant recovery column;

the top of the extractant recovery tower is connected with the upper part of the extractant recovery tower through a tower top condenser of the extractant recovery tower; the bottom of the extractant recovery tower is respectively connected with the lower part of the extractant recovery tower through a reboiler at the bottom of the extractant recovery tower, the upper part of the extraction rectifying tower and the middle part of the reaction rectifying tower;

the top of the product tower is connected with the upper part of the product tower through a product tower top condenser; the bottom of the product tower is connected with the lower part of the product tower through a reboiler at the bottom of the product tower;

wherein, the top condenser of the extraction rectification tower is also sequentially connected with the top condenser of the extractant recovery tower, the top condenser of the product tower and the lower part of the reaction rectification tower; the overhead condenser of the extractant recovery tower is also connected with the middle part of the product tower through a product tower feeding heat exchanger; the product tower top condenser is also connected with the product tower feeding heat exchanger.

2. A process for preparing dimethyl carbonate by reactive distillation coupled with extractive distillation is characterized by comprising the following steps:

s1, feeding a reaction mixture obtained by mixing propylene carbonate, methanol and a catalyst into a reaction rectifying tower through a reaction rectifying tower feeding heat exchanger for treatment to obtain a reaction rectifying tower top gas phase and a reaction rectifying tower bottom liquid phase;

s2, feeding a part of the gas phase at the top of the reactive distillation column and an extracting agent into an extraction distillation column for treatment to obtain a gas phase at the top of the extraction distillation column and a liquid phase at the bottom of the extraction distillation column, and refluxing the other part of the gas phase at the top of the reactive distillation column to the reactive distillation column through a condenser at the top of the reactive distillation column; one part of the liquid phase at the bottom of the reactive distillation tower exchanges heat with the reaction mixture through a reactive distillation tower feeding heat exchanger and then is output, and the other part of the liquid phase flows back to the reactive distillation tower through a reactive distillation tower bottom reboiler;

s3, allowing a part of the gas phase at the top of the extractive distillation column to enter a reactive distillation column through a supercharger, condensing the other part of the gas phase at the top of the extractive distillation column into a condensate a through a condenser at the top of the extractive distillation column, and refluxing a part of the condensate a to the extractive distillation column; one part of the liquid phase at the bottom of the extraction and rectification tower is sent into an extractant recovery tower for treatment to obtain a gas phase at the top of the extractant recovery tower and a liquid phase at the bottom of the extractant recovery tower, and the other part of the liquid phase flows back to the extraction and rectification tower through a reboiler at the bottom of the extraction and rectification tower;

s4, exchanging heat between the gas phase at the top of the extractant recovery tower and the other part of the condensate a through a condenser at the top of the extractant recovery tower to obtain a condensate b and a gas phase c, refluxing one part of the condensate b to the extractant recovery tower, and sending the other part of the condensate b to a product tower through a product tower feeding heat exchanger for treatment to obtain a gas phase at the top of the product tower and a liquid phase at the bottom of the product tower; one part of the liquid phase at the bottom of the extractant recovery tower is respectively sent to the extraction rectifying tower and the reaction rectifying tower, and the other part of the liquid phase flows back to the extractant recovery tower through a reboiler at the bottom of the extractant recovery tower;

s5, exchanging heat between the gas phase at the top of the product tower and the other part of the condensate a through a condenser at the top of the product tower to obtain a condensate d and a gas phase e, mixing the gas phase e and the gas phase c, feeding the mixture into a reactive distillation tower, refluxing one part of the condensate d to the product tower, exchanging heat between the other part of the condensate d and the condensate b through a feed heat exchanger of the product tower, and outputting the other part of the condensate d and the condensate b as a dimethyl carbonate product; and one part of the liquid phase at the bottom of the product tower refluxes to the product tower through a reboiler at the bottom of the product tower, and the other part of the liquid phase is output as a heavy component.

3. The process of claim 2, wherein in S1, the pressure of the reaction mixture is 0.2 to 0.7MPa and the temperature is 30 to 100 ℃.

4. The process of claim 2, wherein in the step of S1, when the reactive distillation column is used for treatment, the pressure at the top of the reactive distillation column is 0.01-0.08MPa, and the temperature at the top of the reactive distillation column is 60-90 ℃.

5. The process of claim 2, wherein in the step S2, when the extractive distillation column is used for processing, the pressure at the top of the column is 0-0.05MPa, and the temperature at the top of the column is 60-85 ℃.

6. The process of claim 2, wherein the extractant recovery column is operated at a pressure of-0.09 MPa to-0.02 MPa and a temperature of 40 ℃ to 90 ℃ at the top of the extractant recovery column in S3.

7. The process of claim 2, wherein in S4, the product column is operated at a pressure of 0 to 0.05MPa at the top and a temperature of 80 to 110 ℃.

Technical Field

The invention relates to the technical field of dimethyl carbonate preparation, in particular to a device and a process for preparing dimethyl carbonate by reactive distillation coupled with extractive distillation.

Background

Dimethyl carbonate (DMC) is an important organic chemical intermediate, and because the molecular structure of the DMC contains carbonyl, methyl, methoxy and carbonylmethoxy, the DMC can be widely used in organic synthesis reactions such as carbonylation, methylation, methoxylation, carbonylmethylation and the like, and because the application is very wide, the DMC is known as a new base stone in the current organic synthesis.

Domestic patents focus on the research and development of DMC synthesis methods and catalysts, the steam consumption is very high in the preparation process of a plurality of dimethyl carbonate, and the technological method of reactive distillation coupled with extractive distillation is very little. In the process of increasing the demand of dimethyl carbonate, not only the selection of a dimethyl carbonate synthesis method and a catalyst but also the selection of an energy-saving consumption-reducing and refining process are considered in the aspect of controlling the cost.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a device and a process for preparing dimethyl carbonate by reactive distillation coupling extraction distillation, which aims at the problem of overlarge steam energy consumption in the ester exchange process, improves the refining process route, saves a large amount of steam and cold energy consumption by applying the reactive distillation coupling extraction distillation technology and methanol gasification post-circulation, and partially extracts a circulating extractant into a reactive distillation tower, thereby avoiding the accumulation of heavy components and being beneficial to ester exchange reaction and distillation separation.

The invention provides a device for preparing dimethyl carbonate by reactive distillation coupled extraction distillation, which comprises: a reaction rectifying tower, an extraction rectifying tower, an extractant recovery tower and a product tower;

the top of the reactive distillation column is respectively connected with the upper part of the reactive distillation column through a tower top condenser of the reactive distillation column and connected with the lower part of the extractive distillation column; the bottom of the reactive distillation tower is respectively connected with a feed heat exchanger of the reactive distillation tower and a reboiler at the bottom of the reactive distillation tower;

the top of the extractive distillation column is respectively connected with a condenser at the top of the extractive distillation column and the lower part of the reactive distillation column through a supercharger; the bottom of the extractive distillation column is respectively connected with the lower part of the extractive distillation column through a reboiler at the bottom of the extractive distillation column and is connected with the middle part of an extractant recovery column;

the top of the extractant recovery tower is connected with the upper part of the extractant recovery tower through a tower top condenser of the extractant recovery tower; the bottom of the extractant recovery tower is respectively connected with the lower part of the extractant recovery tower through a reboiler at the bottom of the extractant recovery tower, the upper part of the extraction rectifying tower and the middle part of the reaction rectifying tower;

the top of the product tower is connected with the upper part of the product tower through a product tower top condenser; the bottom of the product tower is connected with the lower part of the product tower through a reboiler at the bottom of the product tower;

wherein, the top condenser of the extraction rectification tower is also sequentially connected with the top condenser of the extractant recovery tower, the top condenser of the product tower and the lower part of the reaction rectification tower; the overhead condenser of the extractant recovery tower is also connected with the middle part of the product tower through a product tower feeding heat exchanger; the product tower top condenser is also connected with the product tower feeding heat exchanger.

The invention also provides a process for preparing dimethyl carbonate by reactive distillation coupled extraction distillation, which comprises the following steps:

s1, feeding a reaction mixture obtained by mixing propylene carbonate, methanol and a catalyst into a reaction rectifying tower through a reaction rectifying tower feeding heat exchanger for treatment to obtain a reaction rectifying tower top gas phase and a reaction rectifying tower bottom liquid phase;

s2, feeding a part of the gas phase at the top of the reactive distillation column and an extracting agent into an extraction distillation column for treatment to obtain a gas phase at the top of the extraction distillation column and a liquid phase at the bottom of the extraction distillation column, and refluxing the other part of the gas phase at the top of the reactive distillation column to the reactive distillation column through a condenser at the top of the reactive distillation column; one part of the liquid phase at the bottom of the reactive distillation tower exchanges heat with the reaction mixture through a reactive distillation tower feeding heat exchanger and then is output, and the other part of the liquid phase flows back to the reactive distillation tower through a reactive distillation tower bottom reboiler;

s3, allowing a part of the gas phase at the top of the extractive distillation column to enter a reactive distillation column through a supercharger, condensing the other part of the gas phase at the top of the extractive distillation column into a condensate a through a condenser at the top of the extractive distillation column, and refluxing a part of the condensate a to the extractive distillation column; one part of the liquid phase at the bottom of the extraction and rectification tower is sent into an extractant recovery tower for treatment to obtain a gas phase at the top of the extractant recovery tower and a liquid phase at the bottom of the extractant recovery tower, and the other part of the liquid phase flows back to the extraction and rectification tower through a reboiler at the bottom of the extraction and rectification tower;

s4, exchanging heat between the gas phase at the top of the extractant recovery tower and the other part of the condensate a through a condenser at the top of the extractant recovery tower to obtain a condensate b and a gas phase c, refluxing one part of the condensate b to the extractant recovery tower, and sending the other part of the condensate b to a product tower through a product tower feeding heat exchanger for treatment to obtain a gas phase at the top of the product tower and a liquid phase at the bottom of the product tower; one part of the liquid phase at the bottom of the extractant recovery tower is respectively sent to the extraction rectifying tower and the reaction rectifying tower, and the other part of the liquid phase flows back to the extractant recovery tower through a reboiler at the bottom of the extractant recovery tower;

s5, exchanging heat between the gas phase at the top of the product tower and the other part of the condensate a through a condenser at the top of the product tower to obtain a condensate d and a gas phase e, mixing the gas phase e and the gas phase c, feeding the mixture into a reactive distillation tower, refluxing one part of the condensate d to the product tower, exchanging heat between the other part of the condensate d and the condensate b through a feed heat exchanger of the product tower, and outputting the other part of the condensate d and the condensate b as a dimethyl carbonate product; and one part of the liquid phase at the bottom of the product tower refluxes to the product tower through a reboiler at the bottom of the product tower, and the other part of the liquid phase is output as a heavy component.

Preferably, in S1, the pressure of the reaction mixture is 0.2-0.7MPa and the temperature is 30-100 ℃.

Preferably, in S1, when the reactive distillation column is used for processing, the pressure at the top of the column is 0.01-0.08MPa, and the temperature at the top of the column is 60-90 ℃.

Preferably, in S2, when the extractive distillation column is used for processing, the pressure at the top of the column is 0-0.05MPa, and the temperature at the top of the column is 60-85 ℃.

Preferably, in S3, when the extractant recovery tower is used for treatment, the tower top pressure is-0.09 MPa to-0.02 MPa, and the tower top temperature is 40 ℃ to 90 ℃.

Preferably, in S4, when the product tower is used for processing, the pressure at the top of the tower is 0-0.05MPa, and the temperature at the top of the tower is 80-110 ℃.

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

1. the invention utilizes the reactive distillation coupled extractive distillation technology to improve the existing ester exchange reaction process route, thereby improving the technical level of the dimethyl carbonate production process.

2. The invention comprehensively utilizes the technologies of reactive distillation coupling extractive distillation, methanol gasification circulation and heat exchange coupling, thereby saving a large amount of steam and cold consumption.

3. The extraction agent is partially extracted to the reaction rectifying tower, so that the accumulation of heavy components is avoided, and the ester exchange reaction and the rectification separation are facilitated.

Drawings

Fig. 1 is a schematic structural view of embodiment 1 of the present invention.

In the figure, 1, a reaction rectifying tower; 2. an extractive distillation column; 3. an extractant recovery column; 4. a product tower; 5. a condenser at the top of the reaction rectifying tower; 6. a reaction rectifying tower feeding heat exchanger; 7. a reboiler at the bottom of the reaction rectifying tower; 8. a condenser at the top of the extraction rectifying tower; 9. a supercharger; 10. a reboiler at the bottom of the extraction rectifying tower; 11. a condenser at the top of the extractant recovery tower; 12. a reboiler at the bottom of the extractant recovery tower; 13. a product tower top condenser; 14. a reboiler at the bottom of the product tower; 15. a product tower feed heat exchanger; a. a condensate a; b. a condensate b; c. a gas phase c; d. a condensate d; e. gas phase e.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.