WO2020083118A1

WO2020083118A1 - System and process for rapid extraction and refining of ethyl acetate after synthesis by pressurized esterification

Info

Publication number: WO2020083118A1
Application number: PCT/CN2019/112044
Authority: WO
Inventors: 刘强; 李志远; 郭向东; 张玉娟; 于超; 包磊磊; 张宇; 陈明; 梁群; 刘成刚; 杨文攀; 常亮
Original assignee: 兖矿鲁南化工有限公司; 兖矿集团有限公司
Priority date: 2018-10-25
Filing date: 2019-10-18
Publication date: 2020-04-30
Also published as: KR20210050511A; CN109534997A; KR102484021B1; CN109534997B

Abstract

Disclosed are a system and a process for rapid extraction and refining of ethyl acetate after synthesis by pressurized esterification, comprising a reaction rectification tower, a refining tower, a deacidification tower and a recovery tower. A middle portion of the reaction rectification tower is connected to an acetic acid source and an ethanol source, and a top portion of the reaction rectification tower is connected to an inlet of a first collecting tank via a cooler. The first collecting tank is in communication with a first layer, and a top portion of the first layer is in communication with the top portion of the reaction rectification tower and a middle portion of the refining tower respectively. The first layer is in communication with a desalinated water storing unit for replenishing desalinated water to the first layer. The desalinated water replenished to the first layerer can serve as an extractant for extracting light components as well as impurities such as reaction by-products in a crude ester, and can also speed up the rate of replacement of acetic acid content in the crude ester and accelerate the process of obtaining an acceptable product after start-up of the ethyl acetate extraction and refining system.

Description

System and process for quickly extracting pure ethyl acetate after pressure esterification synthesis

Technical field

The invention relates to the field of acetic acid synthesis, in particular to a system and process for rapid extraction of pure ethyl acetate after pressure esterification synthesis.

Background technique

Ethyl acetate, also known as ethyl acetate, is an important downstream product of acetic acid, with excellent solubility and fast drying. In the industry, it is mainly used as a solvent for the production of paints (paints, nuclear enamels), binders, ethyl cellulose, artificial leather, linoleum colorants, and artificial fibers. It can also be used as a binder for the production of printing inks, artificial pearls, etc. . It is used as an extractant in the production of medicines, organic acid products, etc. In addition, it can also be used as a raw material for the production of pineapple, banana, strawberry and other fruit flavor nuclear whiskey, cream and other spices. Ethyl acetate has excellent dissolving power, can be used as a quick-drying solvent, and is widely used in the chemical industry and the pharmaceutical industry.

Acetic acid esterification is the most common production method of ethyl acetate. In the presence of a catalyst, acetic acid and ethanol undergo an esterification reaction to produce ethyl acetate. The ethyl acetate in China is mainly produced by the acetate esterification method, and most of the five towers are used. The rectification process has many equipments and high energy consumption; some ethyl acetate production processes use excessive ethanol to make the acetic acid react as completely as possible to omit the deacidification tower, but the crude ester prepared by this method contains a large amount of The low content of ethanol and ethyl acetate leads to a low purification efficiency of ethyl acetate, resulting in the problem of long production cycle of ethyl acetate. The production process of ethyl acetate is to mix acetic acid, ethanol and catalyst to react in the esterification kettle, and then send the reacted materials to a rectification tower for rectification. Since the reaction of acetic acid and ethanol is a reversible reaction, It is difficult to remove the water produced in the reaction in the esterification kettle in time, which is not conducive to the progress of the esterification reaction, and the content of ethyl acetate in the reaction feed liquid is low, which is not conducive to the subsequent refining and purification process. The traditional esterification method still has the problems of poor quality of ethyl acetate products, high raw material consumption, difficulty in deacidification and long production cycle of ethyl acetate.

Summary of the invention

In view of the above technical problems in the prior art, the object of the present invention is to provide a system and process for rapid extraction of pure ethyl acetate after pressure esterification synthesis.

In order to solve the above problems, the technical solution of the present invention is:

A system for rapid extraction of pure ethyl acetate after pressurized esterification synthesis, including a reactive rectification tower, a purification tower, a deacidification tower and a recovery tower, wherein the middle of the reactive rectification tower is connected to an acetic acid source and an ethanol source, The top of the reaction rectification tower is connected to the inlet of the first collection tank through a cooler, and the first collection tank is also in communication with the first stratifier. The top of the first stratifier is connected to the top of the reaction rectification tower and the The middle part of the refining tower is connected; the first layerer is connected with the desalinated water storage device, and the desalinated water is added to the first layerer;

The top of the refining tower is connected to the inlet of the cooler, the outlet of the cooler is connected to the second collection tank; the middle of the refining tower is connected to the inlet of the second layerer, and the outlet of the organic phase of the second layerer is connected to the refining tower, The bottom of the second layerer communicates with the recovery tower; the tower kettle of the refining tower communicates with the inlet of the deacidification tower;

The top of the deacidification tower is connected to the inlet of the third cooler, the outlet of the third cooler is connected to the third collection tank, and the third collection tank is connected to the finished product tank; the tower kettle of the deacidification tower is connected to the reaction rectification tower Connected.

Add desalinated water to the first layerer (desalted water is water that removes or reduces the strong electrolyte that is easily removed to a certain degree, and the remaining salt content in the desalted water should be between 1-5mg / L), The substance can be used as an extractant to extract impurities such as light components and reaction by-products in the crude ester, and can also accelerate the replacement speed of the acetic acid content in the crude ester and increase the initial product qualification rate of the ethyl acetate unit during the initial operation.

Preferably, the reactor of the reaction rectification tower is connected to the middle of the reaction rectification tower through a pump and a heat exchanger. The acetic acid conveyed to the reaction rectification tower generally accumulates in the reactor of the reaction rectification tower. The pump can transfer the acetic acid accumulated in the tower kettle to the reaction section of the reaction rectification tower after heating. On the one hand, the acetic acid can be added again. Ensure the concentration of acetic acid in the reaction system, promote the conversion rate of ethanol, and increase the content of ethyl acetate. On the other hand, repeated addition of acetic acid can ensure the utilization of acetic acid, prevent the waste of acetic acid, and further simplify the subsequent purification of ethyl acetate Process.

Preferably, a fourth collection tank is connected to the top of the recovery tower.

Further preferably, the top of the recovery tower is connected to the reaction rectification tower through a cooler.

A process for rapid extraction of pure ethyl acetate after pressure esterification synthesis includes the following steps:

The preparation and purification process of ethyl acetate includes the steps of esterification-refining-deacidification-wastewater recovery. After the esterification is completed, the overhead material is cooled and sent to the first layerer for layering, which is added in the first layerer Demineralized water to extract impurities in the crude ester and promote the replacement rate of acetic acid in ethyl acetate.

Preferably, the esterification specifically includes the following steps: after the ethanol and acetic acid are mixed, they enter the reaction rectification tower from the middle; Re-participate in the reaction; the azeotrope of ethyl acetate and water and part of the alcohol are distilled from the top of the reaction rectification tower, after cooling, they are transported by the pump to the first layerer, and the organic phase is collected from the top of the first layerer The water is partly refluxed to the rectification tower, and the rest is heated and transported to the refining tower; the water phase is withdrawn from the bottom of the first layerer and transported to the recovery tower.

Further preferably, the working pressure in the reactive distillation column is 0.15-0.2 MPa, and the working temperature is 120-150 ° C.

Further preferably, the flow ratio of the material refluxed to the rectification tower and the material transported to the purification tower is 1.5-2.0: 1.

Further preferably, the molar ratio of ethanol to acetic acid during the esterification is 0.85-0.97: 1.

Preferably, the refining specifically includes the following steps: the material from the esterification process enters the refining tower from the middle, the light components accumulate in the refining tower and distill out from the top of the tower, and the top-recovered materials are condensed and returned to the top of the refining tower The ethyl acetate is purified from the refining tower and transferred to the deacidification tower from the refining tower;

The purification process of ethyl acetate is as follows: after removing light components in the refining tower, ethyl acetate is produced as an intermediate product from the bottom of the refining tower and sent to the deacidification tower. In order to further reduce system consumption and avoid material loss, it is collected from the middle of the refining tower. Part of the side-mining material is discharged into the second layerer for layering, the water phase sinks in the second layerer, and after preheating it is recovered to the recovery tower, and the organic phase is recycled to the refining tower.

Preferably, the working pressure in the refining step is 0.15-0.23 MPa, and the working temperature is 110-116 ° C.

Preferably, the working pressure of the deacidification step is 0.1-0.15 MPa, and the working temperature is 100-115 ° C.

Preferably, the wastewater recovery step is 0.1-0.15 MPa, and the working temperature is 110-126 ° C.

The beneficial effects of the present invention are:

The invention can rapidly improve the purity of ethyl acetate products, greatly shorten the driving time of the ethyl acetate device, and the driving time can be shortened by at least 8-10 hours at a time. The acid content in ethyl acetate products can be reduced to below 30ppm, and the product purity can be stably controlled at above 99.9%.

The invention can be applied to most ethyl acetate production processes with pressure distillation.

BRIEF DESCRIPTION

The drawings of the description forming part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions of this application are used to explain this application, and do not constitute an undue limitation on this application.

FIG. 1 is a schematic structural diagram of the system of the present invention.

Among them: 1. Reaction rectification tower, 2. First layerer, 3. First collection tank, 4. Refining tower, 5. Second collection tank, 6. Second layerer, 7. Deacidification tower, 8. Third collection tank, 9. Recovery tower, 10. Fourth collection tank.

detailed description

It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanations of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

It should be noted that the terminology used herein is only for describing specific embodiments, and is not intended to limit exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates There are features, steps, operations, devices, components, and / or combinations thereof.

As shown in FIG. 1, a system for rapid extraction of pure ethyl acetate after pressurized esterification synthesis includes a reaction rectification tower 1, a purification tower 4, a deacidification tower 7, and a recovery tower 9, wherein the reaction rectification tower The middle part of 1 is connected with an acetic acid source and an ethanol source, the top of the reactive distillation column 1 is connected with the inlet of the first collection tank 3 through the first cooler, and the first collection tank 3 is communicated with the first layerer 2 The top of the layer 2 is communicated with the top of the reaction rectification tower 1 and the middle of the refining tower 4 respectively; the column kettle of the reaction rectification tower 1 is connected to the middle of the reaction rectification tower 1 through a pump and a heat exchanger.

The top of the refining tower 4 is connected to the inlet of the second cooler, the outlet of the second cooler is connected to the second collecting tank 5, the second collecting pipe 5 communicates with the refining tower 4; the middle of the refining tower 4 is connected to the second layer The inlet of the separator 6 is connected, the organic phase outlet of the second layerer 6 is connected to the refining tower 4, the bottom of the second layerer 6 is connected to the recovery tower 9; the tower kettle of the refining tower 4 and the deacidification tower 7 The entrance of is connected;

The top of the deacidification tower 7 is connected to the inlet of the third cooler, the outlet of the third cooler is connected to the third collection tank 8, and the third collection tank 8 is connected to the finished product tank; The reactive distillation column 1 is in communication. A fourth collection tank 10 is connected to the top of the recovery tower 9.

This set of ethyl acetate device adopts the production process of four-tower rectification. The "esterification-refining-deacidification-wastewater recovery" esterification method produces the four-tower rectification process of ethyl acetate. The whole process consists of reactive rectification process and refining process It consists of deacidification process and recovery process, with simple process and low energy consumption. The new ethyl acetate production process can quickly improve product purity, reduce the content of acetic acid in the product, improve the market competitiveness of ethyl acetate products, and lay the foundation for other downstream products of acetic acid.

Reactive distillation process

The reactive rectification process mainly includes: reactive rectification tower, reboiler, cooler, collection tank, delaminator, and reflux pump. After the ethanol and acetic acid are mixed, they enter the reaction rectification tower from the middle, and an equilibrium reaction occurs in the reaction rectification tower. The gaseous material enters the distillation section of the reaction rectification tower, and excess acetic acid accumulates at the bottom of the reaction rectification tower to participate in the reaction again.

The azeotrope of ethyl acetate and water and part of the alcohol are distilled from the top of the reaction rectification tower, and after cooling, they are transported by the pump to the rectification tower layerer. The organic phase is taken from the top of the stratification device of the rectification tower, and part of it is refluxed to the rectification tower, and the rest is heated and sent to the refining tower, and the materials sent to the refining tower, ethyl acetate, ethanol and water each account for the mass percentage The content is: ethyl acetate 85% ～ 92%, ethanol 2% ～ 5%, water 6% ～ 10%. The aqueous phase is withdrawn from the bottom of the rectifier column layerer and sent to the recovery tower. In order to further achieve the purpose of deacidification and purification of ethyl acetate product purity, additional demineralized water is added in the first layer 2 of the rectification tower. This substance can be used as an extractant to extract the light components in the crude ester and the reaction vice Impurities such as products can accelerate the replacement rate of acetic acid in crude esters and increase the qualified rate of the initial product of the ethyl acetate unit. After adding desalinated water, the mass percentage of ethyl acetate in crude esters is increased from 87 to 91% to 89% ~ 93%, the purity of the obtained ethyl acetate product is above 99.9%, and the use of desalinated water can shorten the qualification rate of ethyl acetate products by 8 to 10 hours. During the initial operation of the ethyl acetate unit, the mass percentage of acetic acid in the top of the reactive distillation column is 0.5% to 1.0%, and the content of acetic acid in the finished product of ethyl acetate requires 0.004% or less. Therefore, the repeated distillation replacement of the reactive distillation system is required. The content of acetic acid in the overhead distillate drops to less than 0.01%, and then enters the refining tower as crude ester for refining. Therefore, the initial product qualification is slow. In order to speed up the replacement of acetic acid in the crude ester, the amount of desalinated water added at the initial start-up is 2 to 6 t / h, and the flow rate ratio to the top distillate is 0.1 to 0.3: 1. Working pressure of reactive distillation tower: 0.15 ～ 0.2MPa; operating temperature of reactive distillation tower: 120 ～ 150 ℃.

Refining process

The refining process mainly includes: refining tower, reboiler, cooler, collecting tank, layerer, and pump. The material from the reactive distillation process enters the refining tower from the middle, and the light components accumulate in the refining tower and distill out from the top of the tower. The top mining material is condensed and used as the reflux of the refining tower. Depending on the temperature of the top of the refining tower, some light components can be taken out intermittently. Ethyl acetate is purified in the stripping section of the refining tower and sent to the deacidification tower as an intermediate product from the tower kettle.

A part of the side mining material is taken from the middle of the tower and enters the refining tower layerer. The water phase sinks and separates in the layerer of the refining tower, and enters the recovery tower through the feed preheater of the recovery tower. The organic phase is recycled to the refinery column feed upstream of the condenser of the rectification column. Working pressure of refining tower: 0.15 ～ 0.23MPa; operating temperature of refining tower: 110 ～ 116 ℃

Deacidification process

Deacidification equipment, including deacidification tower, reboiler, cooler, collection tank, production pump. After removing some light components and other impurities through the refining tower, the crude ester enters the deacidification tower. After being heated by the reboiler, the ethyl acetate product is taken from the top of the tower, cooled by the top cooler and sent to the finished tank area. The products at the bottom of the tower are pumped into the reaction rectification tower for recycling. The working pressure of deacidification tower is 0.1 ～ 0.15MPa; the temperature of sensitive board of deacidification tower is 100 ～ 115 ℃.

Recycling process

The recovery process mainly includes: recovery tower, reboiler, cooler, collection tank, and production pump. The water containing organic matter from the rectifying tower layerer and the refining tower layerer enters the recovery tower. Ethanol and ethyl acetate are concentrated at the top of the tower. After cooling the overhead material, part of the material is sent to the reaction rectification tower for reaction. Qualified waste water after purification is taken from the recovery tower tower kettle and sent to sewage treatment. Working pressure of recovery tower: 0.1 ～ 0.15MPa; operation temperature of recovery tower: 110 ～ 126 ℃

The tower described in the present invention is a rectification tower commonly used in the chemical industry.

The pump used in the present invention is a pump in a general sense, and it is a device for transferring liquid.

The reboiler used in the present invention is a device that uses saturated steam as a heating medium to heat materials.

The above are only the preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

A device for rapid extraction of pure ethyl acetate after pressurized esterification is characterized in that it includes a reaction rectification tower, a purification tower, a deacidification tower and a recovery tower, in which the middle of the reaction rectification tower is connected to the acetic acid source and The ethanol source is connected, the top of the reaction rectification tower is connected to the inlet of the first collection tank through a cooler, the first collection tank is connected to the first layerer, and the top of the first layerer is respectively connected to the top of the reaction rectification tower It communicates with the middle of the refining tower; the first layerer communicates with the desalinated water storage device and supplements the first layerer with desalinated water;

The top of the refining tower is connected to the inlet of the cooler, the outlet of the cooler is connected to the refining tower; the middle of the refining tower is connected to the inlet of the second layerer, and the outlet of the organic phase of the second layerer is connected to the refining tower, the second The bottom of the layerer is in communication with the recovery tower; the tower kettle of the refining tower is in communication with the inlet of the deacidification tower;

The top of the deacidification tower is connected to the inlet of the third cooler, the outlet of the third cooler is connected to the third collection tank, and the third collection tank is connected to the finished product tank; the tower kettle of the deacidification tower is connected to the reaction rectification tower Connected.
The device according to claim 1, characterized in that the reaction rectification tower further comprises a tower kettle, and the tower kettle of the reaction rectification tower is connected to the middle of the reaction rectification tower through a pump and a heat exchanger.
The device according to claim 1, wherein a collection tank is connected to the top of the recovery tower.
The apparatus according to claim 1, wherein the top of the recovery tower is connected to the reaction rectification tower through a cooler.
A process for rapid extraction of pure ethyl acetate after pressure esterification synthesis, which is characterized by the following steps: using the device according to any one of claims 1-4;

The preparation and purification process of ethyl acetate includes the steps of esterification-refining-deacidification-wastewater recovery. After the esterification is completed, the overhead material is cooled and sent to the first layerer for layering, which is added in the first layerer Demineralized water to extract impurities in the crude ester and promote the replacement rate of acetic acid in ethyl acetate.
The process according to claim 5, characterized in that the esterification specifically includes the following steps: after the ethanol and acetic acid are mixed, they enter the reaction rectification tower from the middle, and the gaseous materials enter the stripping section of the reaction rectification tower, and the excess acetic acid Accumulated in the reactor of the reaction rectification tower and re-participated in the reaction; the azeotrope of ethyl acetate and water and some alcohols were distilled from the top of the reaction rectification tower, and after cooling, they were transported by the pump to the first layerer. The organic phase is withdrawn from the top of the first layerer, partly refluxed to the reaction rectification tower, and the rest is heated and transported to the refining tower; the aqueous phase is withdrawn from the bottom of the first layerer and transported to the recovery tower.
The process according to claim 6, characterized in that the working pressure in the reactive distillation column is 0.15-0.2 MPa, and the working temperature is 120-150 ° C.
The process according to claim 6, characterized in that the flow ratio of the material refluxed to the reaction rectification tower and the material transported to the purification tower is 1.5-2.0: 1.
The process according to claim 6, characterized in that the molar ratio of ethanol to acetic acid during the esterification is 0.85-0.97: 1.
The process according to claim 5, characterized in that the refining specifically includes the following steps: the material from the esterification step enters the refining tower from the middle, and the light components accumulate in the refining tower and distill out from the top of the tower. The collected materials are condensed and refluxed to the top of the refining tower. After the refining tower is purified, ethyl acetate is transferred from the refining tower to the deacidification tower;

The purification process of ethyl acetate is as follows: ethyl acetate is removed from the refining tower as an intermediate product from the bottom of the refining tower and then sent to the deacidification tower as an intermediate product. The stratifier is stratified, the water phase sinks in the second stratifier, and is recovered to the recovery tower after preheating, and the organic phase is circulated to the refining tower;

Among them, the top mining material is the material extracted from the top of the refining tower, and the side mining material is the material collected from the middle of the refining tower.
The process according to claim 5, characterized in that the working pressure in the refining step is 0.15-0.23 MPa and the working temperature is 110-116 ° C.
The process according to claim 5, characterized in that the working pressure of the deacidification step is 0.1-0.15 MPa, and the working temperature is 100-115 ° C.
The process according to claim 5, characterized in that the working pressure of the wastewater recovery step is 0.1-0.15 MPa, and the working temperature is 110-126 ° C.