阅读说明：本技术 一种乙二醇的分离方法 (Method for separating ethylene glycol ) 是由 杨建春 于 2020-07-23 设计创作，主要内容包括：本发明公开一种乙二醇的分离方法。该分离方法包括如下步骤：将草酸二甲酯加氢单元得到含有氢气、水、甲醇和乙二醇的气体物料分步降温冷凝,得到粗乙二醇液体物料和粗甲醇液体物料,粗乙二醇液体物料和粗甲醇液体物料中的至少一种物料在送入分离单元之前部分气化；所述部分气化的热源优选为草酸二甲酯加氢单元得到的气体物料。本发明的方法节约了反应气体冷凝及精馏分离塔的能耗。(The invention discloses a method for separating ethylene glycol. The separation method comprises the following steps: the method comprises the steps of cooling and condensing a gas material containing hydrogen, water, methanol and glycol obtained by a dimethyl oxalate hydrogenation unit step by step to obtain a crude glycol liquid material and a crude methanol liquid material, wherein at least one of the crude glycol liquid material and the crude methanol liquid material is partially gasified before being sent into a separation unit; the heat source for partial gasification is preferably a gas material obtained by a dimethyl oxalate hydrogenation unit. The method of the invention saves the energy consumption of the reaction gas condensation and the rectification separation tower.)

1. A method for separating ethylene glycol, characterized in that the method comprises the following steps: cooling and condensing the gas material obtained by the dimethyl oxalate hydrogenation unit step by step to obtain a crude glycol liquid material and a crude methanol liquid material, wherein at least one of the crude glycol liquid material and the crude methanol liquid material is partially gasified before being sent to the separation unit;

the gaseous feed contains hydrogen, water, methanol and ethylene glycol.

2. The separation process of claim 1, wherein the source of heat for the partial gasification is selected from at least one of steam, a gas feed to the top of a separation column in a separation unit, a gas feed from a dimethyl oxalate hydrogenation unit; preferably a gaseous feed from a dimethyl oxalate hydrogenation unit.

3. The separation process of claim 1 or 2, wherein the crude methanol liquid feed and/or the crude ethylene glycol liquid feed is warmed by heat exchange with at least one of steam, a gas feed from the top of the separation column in the separation unit, and a gas feed from the dimethyl oxalate hydrogenation unit to partially vaporize the feed prior to being fed to the separation unit.

Preferably, the temperature difference between the crude methanol liquid feed and/or the crude ethylene glycol liquid feed and the heat source is 50-200 ℃.

Preferably, the temperature difference between the crude methanol liquid material and/or the crude glycol liquid material after the heat exchange and the temperature increase is 30-160 ℃ compared with the temperature difference before the heat exchange and the temperature increase.

More preferably, the temperature of the crude methanol liquid feed and/or the crude ethylene glycol liquid feed after the temperature increase by heat exchange is in the range of from 70 to 170 ℃.

4. The separation process according to any one of claims 2 or 3, wherein the separation column overhead gas stream is a pressurized overhead gas stream. Preferably, said pressurisation is achieved by a compressor.

5. The separation unit of any one of claims 2-4, wherein the dimethyl oxalate hydrogenation unit is a reaction unit in the production of ethylene glycol from coal-based syngas.

Preferably, the process for hydrogenating the dimethyl oxalate comprises the following steps: dimethyl oxalate (DMO) is subjected to catalytic hydrogenation reaction at the temperature of 180-225 ℃ and under the pressure of 2.5-3.0MPa to obtain a reaction product containing ethylene glycol.

Preferably, the temperature of the gas material obtained by the dimethyl oxalate hydrogenation unit is 180-210 ℃.

Preferably, the pressure of the gas material obtained by the dimethyl oxalate hydrogenation unit is 2.5-3.0 MPa.

6. The separation process of claim 5, wherein the reaction product further comprises unreacted starting hydrogen and by-products.

Preferably, the by-product contains at least one of Butanediol (BDO), ethanol, Propylene Glycol (PG), Methyl Glycolate (MG), water.

Preferably, the reaction product also contains an inert gas. Preferably, the reaction product comprises, in mass percent: 5 to 25 weight percent of nitrogen and/or methane, 30 to 60 weight percent of hydrogen, 15 to 30 weight percent of methanol, 15 to 20 weight percent of ethylene glycol, 0.1 to 2 weight percent of propylene glycol, 0.05 to 2.0 weight percent of butanediol, 0.1 to 5 weight percent of methyl glycolate and 0.1 to 0.6 weight percent of ethanol.

7. The separation process according to any one of claims 1 to 6, wherein the fractional reduced temperature condensation is subjected to at least two condensation stages. For example, the first stage condensation temperature is 110-; the temperature of the second stage condensation is, for example, 20 to 50 ℃.

8. The separation process according to any one of claims 1 to 7, wherein the crude ethylene glycol liquid material is a liquid phase obtained by first-stage condensation of a gaseous material obtained from the dimethyl oxalate hydrogenation unit. Preferably, a first condensed gas phase stream is also obtained after the first stage condensation.

Preferably, the crude methanol liquid material is a liquid phase material obtained after the gas phase material flow after the first stage condensation is subjected to the second stage condensation. Preferably, said second stage of condensation also results in a second stage of condensed vapour phase stream. For example, the gas phase material flow after the second stage condensation is hydrogen containing inert gases such as nitrogen, and the hydrogen is returned to the dimethyl oxalate hydrogenation unit for reuse after further treatment.

9. The separation method according to any one of claims 2 to 8, characterized in that at least one of the crude methanol liquid material and the crude ethylene glycol liquid material is subjected to partial gasification and then enters a separation tower to be separated to obtain a methanol and alcohol ester mixture.

Preferably, the crude methanol liquid material and the crude ethylene glycol liquid material are combined and then enter a separation tower to be separated to obtain a methanol and alcohol ester mixture. Specifically, the crude methanol liquid material is partially gasified and then combined with the crude glycol liquid material, and then the mixture enters a separation tower to be separated to obtain a methanol and alcohol ester mixture.

Preferably, the crude methanol liquid material and the crude glycol liquid material enter different separation towers respectively; for example, the separation column comprises two columns: a column for separating a crude methanol liquid feed and a column for separating a crude ethylene glycol liquid feed.

10. The separation method according to claim 9, wherein the alcohol ester mixture is separated into ethylene glycol through an ester separation tower, a light component removal tower and an ethylene glycol refining tower.

Technical Field

The invention belongs to the technical field of ethylene glycol separation, and particularly relates to a method for separating ethylene glycol.

Background

Ethylene Glycol (EG) is used for the production of polyester resins, antifreeze solutions and the like, of which about 95% is used for the production of polyester fiber products. The preparation method of the ethylene glycol can be divided into a petroleum route method and a non-petroleum route method, the non-petroleum route technology for preparing the ethylene glycol by using the coal synthesis gas has the advantages of less waste discharge, low energy consumption, low cost and the like, and is a better choice for the energy conditions of relatively rich coal resources, less oil and gas shortage in China, so that the technology for preparing the ethylene glycol from the coal is greatly developed in China in recent years.

The current common process for preparing ethylene glycol from coal-based syngas (coal-based ethylene glycol for short) comprises a synthesis step and a post-treatment step, wherein the synthesis step is to prepare pure H from syngas (for example, coal gasification₂And CO gas, namely synthesis gas), preparing methyl nitrite, synthesizing dimethyl oxalate through CO gas-phase catalytic coupling, and preparing ethylene glycol through dimethyl oxalate hydrogenation, wherein the reaction process is shown in the following reaction equation:

2NO+1/2O₂+2CH₃OH＝2CH₃ONO(MN)+H₂O

2CH₃ONO+2CO＝CH₃OOCCOOCH₃(DMO)+2NO

CH₃OOCCOOCH₃+4H₂＝(CH₂OH)₂(EG)+2CH₃OH；

the post-treatment step includes steps of regeneration of Methyl Nitrite (MN), purification of Ethylene Glycol (EG), and the like.

However, the reaction of the coal-to-ethylene glycol process is complex, excessive side reactions cause too many impurities in the ethylene glycol product, the components are complex and difficult to separate, and the separation energy consumption is high. The energy consumption of the device for preparing the ethylene glycol from the coal is reduced, the economic and technical competitiveness of the process is improved, and the method is a necessary way for the development of the process for preparing the ethylene glycol from the coal.

Disclosure of Invention

The invention provides a method for separating ethylene glycol, which comprises the following steps: cooling and condensing the gas material obtained by the dimethyl oxalate hydrogenation unit step by step to obtain a crude glycol liquid material and a crude methanol liquid material, wherein at least one of the crude glycol liquid material and the crude methanol liquid material is partially gasified before being sent to the separation unit;

the gaseous feed contains hydrogen, water, methanol and ethylene glycol.

According to an embodiment of the invention, the source of heat for the partial gasification may be selected from at least one of steam, a gas feed from a separation column overhead in a separation unit, a gas feed from a dimethyl oxalate hydrogenation unit. Illustrative is the gaseous feed from a dimethyl oxalate hydrogenation unit.

According to an embodiment of the invention, the crude methanol liquid material and/or the crude ethylene glycol liquid material is heated in a heat exchange manner with at least one heat source of steam, a gas material at the top of a separation tower in the separation unit and a gas material obtained by a dimethyl oxalate hydrogenation unit before being sent into the separation unit, so that the materials are partially gasified.

Preferably, the temperature difference between the crude methanol liquid feed and/or the crude ethylene glycol liquid feed and the heat source is 50-200 ℃, such as 100-.

Preferably, the temperature of the crude methanol liquid stream and/or the crude ethylene glycol liquid stream after the heat exchange attemperation is 30 to 160 ℃, such as 50 to 150 ℃, exemplary 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃ different from the temperature of the crude methanol liquid stream before the heat exchange attemperation.

More preferably, the temperature of the crude methanol liquid stream and/or the crude ethylene glycol liquid stream after heat exchange for warming is 70-170 deg.C, such as 120-160 deg.C, exemplary 120 deg.C, 130 deg.C, 140 deg.C, 145 deg.C, 150 deg.C, 155 deg.C, 160 deg.C.

Preferably, the separation column overhead gas stream is a pressurized overhead gas stream. Further, the pressurization may be achieved by a compressor.

Preferably, the temperature of the gas material obtained from the dimethyl oxalate hydrogenation unit is 180-210 ℃, such as 185-205 ℃, exemplarily 180 ℃, 185 ℃, 190 ℃, 195 ℃, 200 ℃, 205 ℃ and 210 ℃.

Preferably, the pressure of the gaseous feed from the dimethyl oxalate hydrogenation unit is 2.5-3.0MPa, such as 2.6-2.9MPa, exemplary 2.5MPa, 2.6MPa, 2.7MPa, 2.8MPa, 2.9MPa, 3.0 MPa.

According to the embodiment of the invention, the dimethyl oxalate hydrogenation unit is a reaction unit in the preparation of ethylene glycol from coal-based synthesis gas.

According to an embodiment of the present invention, the process of hydrogenating dimethyl oxalate comprises: dimethyl oxalate (DMO) is subjected to catalytic hydrogenation reaction at the temperature of 180-225 ℃ and under the pressure of 2.5-3.0MPa to obtain a reaction product containing ethylene glycol. Wherein the reaction product further contains unreacted raw material hydrogen and by-products. For example, the by-product contains at least one of Butanediol (BDO), ethanol, Propylene Glycol (PG), Methyl Glycolate (MG), water, and the like. Further, the reaction product may also contain inert gases such as nitrogen and/or methane. Illustratively, the reaction products include, in mass percent: 5 to 25 weight percent of nitrogen and/or methane, 30 to 60 weight percent of hydrogen, 15 to 30 weight percent of methanol, 15 to 20 weight percent of ethylene glycol, 0.1 to 2 weight percent of propylene glycol, 0.05 to 2.0 weight percent of butanediol, 0.1 to 5 weight percent of methyl glycolate and 0.1 to 0.6 weight percent of ethanol.

According to an embodiment of the invention, the fractional desuperheating condensation is subjected to at least two condensation stages. For example, the first stage condensation temperature is 110-. For example, the temperature of the second stage condensation is 20-50 deg.C, illustratively 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C.

According to the embodiment of the invention, the crude ethylene glycol liquid material is a liquid phase material obtained after the gas material obtained by the dimethyl oxalate hydrogenation unit is subjected to first-stage condensation. For example, the crude ethylene glycol liquid material contains 72-85 wt% of ethylene glycol, 1-10 wt% of methanol, 0.1-10 wt% of methyl glycolate, 0.1-4 wt% of propylene glycol and 0.1-5 wt% of butanediol in percentage by mass. Preferably, a first condensed gas phase stream is also obtained after the first stage condensation.

According to an embodiment of the present invention, the crude methanol liquid material is a liquid phase obtained after the gas phase stream after the first stage condensation is subjected to the second stage condensation. For example, the crude methanol liquid material contains 50-70 wt% of methanol, 10-25 wt% of ethylene glycol, 0.3-15 wt% of methyl glycolate, 0.1-2 wt% of propylene glycol and 0.05-2 wt% of butanediol. Preferably, said second stage of condensation also results in a second stage of condensed vapour phase stream. For example, the gas phase stream after the second stage condensation is hydrogen containing inert gases such as nitrogen, and the hydrogen is returned to the dimethyl oxalate hydrogenation unit for reuse after further treatment.

According to an embodiment of the present invention, at least one of the crude methanol liquid feed and the crude ethanol liquid feed is subjected to partial gasification and then enters a separation tower to be separated to obtain a methanol and alcohol ester mixture.

According to an embodiment of the present invention, the crude methanol liquid stream may be combined with a crude ethylene glycol liquid stream and then fed to a separation column for separation to produce a methanol and alcohol ester mixture. Specifically, the crude methanol liquid material is partially gasified and then combined with the crude glycol liquid material, and then the mixture enters a separation tower to be separated to obtain a methanol and alcohol ester mixture.

According to an embodiment of the invention, the crude methanol liquid feed and the crude ethylene glycol liquid feed may be fed to different separation columns, respectively. For example, the separation column may comprise two columns, namely a column for separating a crude methanol liquid feed and a column for separating a crude ethylene glycol liquid feed, to obtain methanol and an alcohol ester mixture, respectively.

According to the embodiment of the invention, the alcohol ester mixture is separated into the ethylene glycol through an ester separation tower, a light component removal tower and an ethylene glycol rectification tower.

According to the embodiment of the invention, the temperature of the top of the separation tower for separating the crude methanol liquid material is 40-70 ℃, the pressure of the top of the separation tower is 0.07-0.12MPa, the temperature of the bottom of the separation tower is 80-180 ℃, the pressure of the bottom of the separation tower is 0.1-0.15MPa, methanol is obtained at the top of the separation tower, and the alcohol ester mixture material is obtained at the bottom of the separation tower. For example, the alcohol ester mixture material contains 70-80 wt% of Ethylene Glycol (EG), 2-5 wt% of butanediol, 2-10 wt% of propylene glycol and 5-20 wt% of glycolic acid in percentage by mass.

The invention has the beneficial effects that:

the invention provides a method for separating ethylene glycol, which comprises the steps of cooling and condensing high-temperature gas materials containing hydrogen, water, methanol and ethylene glycol obtained by a dimethyl oxalate (DMO) hydrogenation reaction unit step by step to respectively obtain crude ethylene glycol liquid materials with high ethylene glycol content and crude methanol liquid materials with high methanol content, wherein the crude ethylene glycol liquid materials and/or the crude methanol liquid materials are partially gasified by heat exchange with a heat source before being sent into the separation unit. Separating by a separation tower to obtain a mixture of methanol and alcohol ester (including high content of glycol), and further purifying and separating the alcohol ester mixture to obtain the glycol. The method of the invention saves the energy consumption of the reaction gas condensation and the rectification separation tower.

Drawings

Fig. 1 is a schematic structural diagram of an ethylene glycol separation device.

Reference numerals: r, a catalytic hydrogenation reactor, E, a heat exchanger, C1, a first-stage condenser, C2, a second-stage condenser, V1, a first fraction liquid tank, V2, a second fraction liquid tank, T and a separation tower.

1. High-temperature reaction gas-phase product, 2, heat exchange reaction gas-phase product, 3, first-stage condensation reaction product, 4, first-stage condensation gas-phase product, 5, second-stage condensation reaction product, 6, hydrogen containing inert gas, 7, crude methanol liquid material, 8, crude glycol liquid material, 9, temperature-increased crude methanol liquid material, 10, alcohol ester mixture, 11 and methanol.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.