阅读说明：本技术 从费托合成水相产物精制乙醇的方法和装置 (Method and device for refining ethanol from Fischer-Tropsch synthesis water phase product ) 是由 金政伟 汤志刚 刘素丽 郭栋 杨自玲 贲国勋 石博文 袁华 冯光华 石好亮 朱楠 于 2020-12-17 设计创作，主要内容包括：本发明涉及精细化工领域,公开了一种从费托合成水相产物精制乙醇的方法和装置,该方法包括：(1)将甲醇和含有氧化物杂质的粗乙醇相接触进行共沸精馏,得到甲醇与氧化物杂质形成的共沸物,以及净化乙醇；(2)将水和所述共沸物进行萃取精馏,得到氧化物杂质和含甲醇水溶液,所述含甲醇的水溶液经分离得到回收甲醇和回收水。利用本发明工艺可降低乙醇净化的成本,提高乙醇的回收率。(The invention relates to the field of fine chemical engineering, and discloses a method and a device for refining ethanol from a Fischer-Tropsch synthesis water phase product, wherein the method comprises the following steps: (1) contacting methanol and crude ethanol containing oxide impurities for azeotropic distillation to obtain an azeotrope formed by the methanol and the oxide impurities, and purifying the ethanol; (2) and (3) carrying out extractive distillation on the water and the azeotrope to obtain oxide impurities and an aqueous solution containing methanol, and separating the aqueous solution containing methanol to obtain recovered methanol and recovered water. The process can reduce the cost of ethanol purification and improve the recovery rate of ethanol.)

1. A process for the purification of ethanol from an aqueous phase product of fischer-tropsch synthesis, the process comprising:

(1) contacting methanol and crude ethanol containing oxide impurities for azeotropic distillation to obtain an azeotrope formed by the methanol and the oxide impurities, and purifying the ethanol;

(2) and (3) carrying out extractive distillation on the water and the azeotrope to obtain oxide impurities and an aqueous solution containing methanol, and separating the aqueous solution containing methanol to obtain recovered methanol and recovered water.

2. The process according to claim 1, wherein in step (1), the crude ethanol comprises 1 to 20% by weight, preferably 2 to 10% by weight, of the oxygenate impurities.

3. The process of claim 1 or 2, wherein in step (1), the oxide impurity is selected from C₁-C₈Aldehyde, C₁-C₈Acid of (C)₃-C₈Ketone and C₂-C₈Preferably at least one selected from the group consisting of acetaldehyde, butyraldehyde, ethyl acetate, acetone and 2-butanone, more preferably at least one selected from the group consisting of ethyl acetate, butyraldehyde and 2-butanone;

and/or, in the crude ethanol, the weight percentage content of the ethyl acetate is 0.5-10%, preferably 1-5%;

and/or, in the crude ethanol, the weight percentage content of butyraldehyde is 0.5-10%, preferably 1-5%;

and/or, the weight percentage of the 2-butanone in the crude ethanol is 0.5-10%, preferably 1-5%.

4. The process according to any one of claims 1 to 3, wherein in step (1), the weight ratio of methanol to the crude ethanol is (0.05-2): 1, preferably (0.1-1): 1.

5. the process according to any one of claims 1 to 4, wherein in step (1), the azeotropic distillation is carried out in an azeotropic distillation column, the reflux ratio of the azeotropic distillation is from 0.35 to 10, preferably from 1.35 to 3.5; the operation pressure of the top of the azeotropic distillation tower is 95-150kPa, and preferably 100-110 kPa; the operation temperature of the top of the azeotropic distillation tower is 70-90 ℃, preferably 72-78 ℃, and the operation temperature of the bottom of the azeotropic distillation tower is 78-96 ℃, preferably 80-90 ℃.

6. The process according to any one of claims 1 to 5, wherein in step (2), the weight ratio of water to azeotrope is (0.5 to 5): 1, preferably (1-2): 1.

7. the process according to any one of claims 1 to 6, wherein in step (2), the extractive distillation is carried out in an extractive distillation column, and the reflux ratio of the extractive distillation is 0.1 to 5, preferably 0.5 to 2.5; the operation pressure of the top of the extraction and rectification tower is 90-150kPa, preferably 100-110 kPa; the operation temperature of the top of the extractive distillation tower is 78-90 ℃, preferably 78.5-80.5 ℃, and the temperature of the bottom of the extractive distillation tower is 90-115 ℃, preferably 95-105 ℃.

8. The process of any one of claims 1-7, further comprising recycling the recovered methanol for azeotropic distillation and recycling recovered water for extracting methanol.

9. The process according to any one of claims 1 to 8, wherein the recovery of purified ethanol is 86-95%, preferably 90-95%; the purity of the purified ethanol is 95-99.9 wt%; preferably 98-99.9 wt%.

10. A device for refining ethanol from a Fischer-Tropsch synthesis water phase product is characterized by comprising an azeotropic rectifying tower (1), an extractive rectifying tower (2) and a separation unit, wherein,

the azeotropic distillation tower (1) is used for carrying out azeotropic distillation on methanol and crude ethanol containing oxide impurities to obtain an azeotrope and purified ethanol;

the extractive distillation tower (2) is communicated with the azeotropic distillation tower (1) and is used for carrying out extractive distillation on the azeotrope and water to obtain oxide impurities and a methanol-containing aqueous solution;

the separation unit is communicated with the extractive distillation tower (2) and is used for separating the methanol-containing aqueous solution to obtain recovered methanol and recovered water;

preferably, the separation unit is communicated with the azeotropic distillation tower (1) and the extractive distillation tower (2) and is used for returning the recovered methanol to the azeotropic distillation tower (1) and returning the recovered water to the extractive distillation tower (2).

Technical Field

The invention relates to the field of fine chemical engineering, in particular to a method and a device for refining ethanol from a Fischer-Tropsch synthesis water phase product.

Background

Fischer-Tropsch synthesis is a core technology of coal indirect liquefaction, coal is gasified to obtain synthesis gas, the synthesis gas is subjected to Fischer-Tropsch synthesis to obtain hydrocarbon products, commonly adopted catalysts comprise an iron-based catalyst and a cobalt-based catalyst, and the obtained products mainly comprise gasoline, diesel oil, kerosene, wax and the like. The Fischer-Tropsch process adopting the iron-based catalyst can generate about 1.2t of synthetic water phase by-products when 1t of oil product is produced. After the synthesized aqueous phase by-product is subjected to preliminary dehydration treatment, the remaining mixed liquor is low-carbon mixed alcohol, namely the mixed liquor of methanol, ethanol, propanol and the like and water. The alcohols are separated from the water-containing raw material solution, particularly methanol, ethanol and propanol with larger content are sold as products, and the comprehensive benefit of the indirect liquefaction device can be effectively improved. However, the mixed lower alcohols obtained from fischer-tropsch synthesis often contain other aldehydes (such as acetaldehyde), ketones (such as acetone and 2-butanone), and esters (such as ethyl acetate), which often affect the purity of the product during purification of the alcohol product and require purification. For example, in the separation and recovery of ethanol, it is often necessary to separate ethyl acetate (77 ℃ C.) and 2-butanone (79.6 ℃ C.).

At present, the separation and purification of products by means of the formation of heterogeneous or homogeneous azeotropes is an important azeotropic rectification stage. Such as alcohol dehydration and purification of ester products, and the like, and the used entrainer is benzene, cyclohexane and the like; for example, dehydration is carried out from ethanol containing methanol, and the adopted entrainer is benzene, cyclohexane, diisopropyl ether and the like; for example, the dehydration is carried out from methyl ethyl ketone, and hexane and the like are used as an azeotropic agent; such as dehydration from ethanol containing methanol and dioxane, and the adopted entrainer is hexane, benzene, etc.; such as dehydration from isopropanol, using an entrainer such as cyclohexane and benzene.

However, when the conventionally used entrainer such as benzene, cyclohexane and diisopropyl ether is used in the system of the present invention, since benzene, cyclohexane, diisopropyl ether and 2-butanone, ethyl acetate and ethanol can form binary azeotrope or ternary azeotrope, when 2-butanone and ethyl acetate are removed from ethanol, a large amount of ethanol loss is caused, and the ethanol yield is reduced; meanwhile, the entrainer needs to be purchased externally, so that the production cost is high. Water is also considered as an entrainer, but the same can form binary azeotrope or ternary azeotrope with ethyl acetate and ethanol, causing ethanol loss; in addition, the latent heat of vaporization of water is large, and the energy consumption in the separation process is too large.

Therefore, a method for purifying ethanol from low-carbon mixed alcohol synthesized by a Fischer-Tropsch process at low cost and high recovery rate is needed.

Disclosure of Invention

The invention aims to overcome the technical problems that water, cyclohexane, benzene and the like are adopted as an entrainer and can possibly form azeotropy with ethanol in Fischer-Tropsch synthesized low-carbon alcohol to cause large ethanol loss, the entrainer needs to be purchased externally and the cost is high in the prior art, and provides a method for refining ethanol from a Fischer-Tropsch synthesized water-phase product.

In order to achieve the above object, the present invention provides in a first aspect a process for the purification of ethanol from an aqueous phase product of fischer-tropsch synthesis, the process comprising:

(1) contacting methanol and crude ethanol containing oxide impurities for azeotropic distillation to obtain an azeotrope formed by the methanol and the oxide impurities, and purifying the ethanol;

(2) and (3) carrying out extraction rectification on water and the azeotrope to obtain oxide impurities and a methanol-containing aqueous solution, and separating the methanol-containing aqueous solution to obtain recovered methanol and recovered water.

The invention provides a device for refining ethanol from a Fischer-Tropsch synthesis water phase product, which comprises an azeotropic rectifying tower, an extractive rectifying tower and a separation unit, wherein,

the azeotropic distillation tower is used for carrying out azeotropic distillation on methanol and crude ethanol containing oxide impurities to obtain an azeotrope and purified ethanol;

the extraction rectifying tower is communicated with the azeotropic rectifying tower and is used for carrying out extraction rectification on the azeotrope and water to obtain oxide impurities and a methanol-containing aqueous solution;

the separation unit is communicated with the extraction and rectification tower and is used for separating the methanol-containing aqueous solution to obtain recovered methanol and recovered water;

preferably, the separation unit is communicated with the azeotropic distillation tower and the extractive distillation tower and is used for returning the recovered methanol to the azeotropic distillation tower and returning the recovered water to the extractive distillation tower.

According to the technical scheme, methanol is used as an entrainer, water is used as an extractant, azeotropic distillation and extraction rectification are utilized, and oxide impurities are removed from crude ethanol obtained by Fischer-Tropsch synthesis to obtain purified ethanol; the process can reduce the cost of ethanol purification and improve the recovery rate of ethanol.

Compared with the prior art, the method for refining the ethanol from the aqueous phase product of the Fischer-Tropsch synthesis provided by the invention at least has the following advantages:

(1) in the method, the methanol only forms an azeotrope with oxide impurities and does not form an azeotrope with the ethanol, so that the loss of the ethanol is not influenced, and the recovery rate of the ethanol is improved;

(2) in the method, the methanol has higher polarity, and the methanol is easy to be separated from the azeotrope by taking water as an extracting agent and recycled;

(3) in the method, methanol is used as an entrainer, and the methanol contained in the mixed alcohol generated by Fischer-Tropsch synthesis can be fully utilized, so that the process can reduce the cost of ethanol separation.

Drawings

FIG. 1 is a schematic flow diagram of a process for the purification of ethanol from an aqueous Fischer-Tropsch synthesis product according to one embodiment of the invention.

Description of the reference numerals

1. An azeotropic distillation column; 2. an extraction rectifying tower.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, one or more new ranges of values may be obtained from combinations of values between the endpoints of each range, the endpoints of each range and the individual values, and the individual values of the points, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, the separation unit is not shown in fig. 1.

In one embodiment of the invention as illustrated in FIG. 1, a first aspect of the invention provides a process for the purification of ethanol from an aqueous phase product of Fischer-Tropsch synthesis, the process comprising:

(1) contacting methanol and crude ethanol containing oxide impurities for azeotropic distillation to obtain an azeotrope formed by the methanol and the oxide impurities, and purifying the ethanol;

(2) and (3) carrying out extraction rectification on water and the azeotrope to obtain oxide impurities and a methanol-containing aqueous solution, and separating the methanol-containing aqueous solution to obtain recovered methanol and recovered water.

According to some embodiments of the present invention, preferably, the crude ethanol may have a weight percentage of the oxygenate impurities of 1 to 20%, more preferably 2 to 10%.

According to some embodiments of the present invention, the crude ethanol containing oxide impurities may be obtained after a preliminary treatment of the aqueous phase product of the fischer-tropsch synthesis, wherein the oxide impurities may be selected from C₁-C₈Aldehyde, C₁-C₈Acid of (C)₃-C₈Ketone and C₂-C₈Preferably at least one selected from acetaldehyde, butyraldehyde, ethyl acetate, acetone and 2-butanone, more preferably at least one selected from ethyl acetate, butyraldehyde and 2-butanone, and further preferably selected from ethyl acetate and/or 2-butanone.

According to some embodiments of the present invention, the ethyl acetate may be present in the crude ethanol in an amount of 0.5 to 10% by weight, more preferably 1 to 5% by weight.

According to some embodiments of the present invention, the crude ethanol may preferably comprise butyraldehyde in an amount ranging from 0.5 to 10% by weight, more preferably from 1 to 5% by weight.

According to some embodiments of the present invention, preferably, the 2-butanone may be present in the crude ethanol in a weight percent amount ranging from 0.5% to 10%, more preferably from 1% to 5%.

According to some embodiments of the present invention, preferably, in step (1), the azeotropic distillation may be performed in an azeotropic distillation column 1, wherein the number of plates of the azeotropic distillation column 1 is preferably 20 to 60, more preferably 30 to 40.

According to some embodiments of the present invention, preferably, the azeotropic distillation may be carried out in the presence of an entrainer, which is preferably methanol.

According to some embodiments of the present invention, preferably, in step (1), the weight ratio of methanol to the crude ethanol may be (0.05-2): 1, more preferably (0.1-1): 1.

according to a preferred embodiment of the present invention, in order to make the oxide impurity and methanol form an azeotrope better, the entrainer is introduced at the middle upper part of the azeotropic distillation tower 1, preferably at the 5 th to 10 th tower plates; the crude ethanol is introduced in the middle of the azeotropic distillation tower 1, preferably in the 15 th to 20 th tower plates.

According to some embodiments of the present invention, preferably, in step (1), the reflux ratio of the azeotropic distillation may be 0.35 to 10, more preferably 1.35 to 3.5.

According to some embodiments of the present invention, preferably, in the step (1), the operation pressure at the top of the azeotropic distillation column 1 may be 95 to 150kPa, preferably 100 to 110 kPa; the operation temperature of the top of the azeotropic distillation tower 1 is 70-90 ℃, preferably 72-78 ℃, and the operation temperature of the bottom of the azeotropic distillation tower 1 is 78-96 ℃, preferably 80-90 ℃.

According to some embodiments of the invention, in step (2), the weight ratio of water to azeotrope may be (0.5 to 5): 1, preferably (1-2): 1.

according to some embodiments of the present invention, preferably, in step (2), the extractive distillation may be performed in the extractive distillation column 2, wherein the number of plates of the extractive distillation column 2 may be 10 to 80, preferably 45 to 55.

According to some embodiments of the invention, the extractive distillation is preferably carried out in the presence of an extractant, which is preferably water.

According to some embodiments of the present invention, in order to enable better extraction of methanol, the extractant may preferably be introduced at the upper middle portion of extractive distillation column 2, preferably at trays 2 to 10; the azeotrope can be introduced in the middle of the extractive distillation column 2, preferably at the 35 th to 40 th tray.

According to some embodiments of the present invention, the reflux ratio of the extractive distillation may be preferably 0.1 to 5, preferably 0.5 to 2.5.

According to some embodiments of the present invention, in the step (2), the operation pressure of the top of the extractive distillation column 2 is 90 to 150kPa, preferably 100 to 110 kPa; the operation temperature of the top of the extraction and rectification tower 2 is 78-90 ℃, preferably 78.5-80.5 ℃, and the temperature of the bottom of the extraction and rectification tower is 90-115 ℃, preferably 95-105 ℃.

According to some embodiments of the invention, the method may further comprise recycling the recovered methanol for azeotropic distillation and recycling the recovered water for extracting methanol.

According to some embodiments of the present invention, the method for separating the aqueous solution containing methanol is not particularly limited, and the separation may be performed by referring to a method for separating methanol and water existing in the art. Preferably, in step (2), the separation of the aqueous solution containing methanol is carried out in a rectification column.

According to some embodiments of the invention, the recovery of purified ethanol is 86-95%, preferably 90-95%; the purity of the purified ethanol is 95-99.9 wt%; preferably 98-99.9 wt%.

In the present invention, the pressure mean absolute pressure is not specifically described.

In the present invention, the number of plates is referred to as "theoretical plate number" unless otherwise specified.

The second aspect of the invention provides an apparatus for purifying ethanol from an aqueous phase product of Fischer-Tropsch synthesis, which comprises an azeotropic distillation column 1, an extractive distillation column 2 and a separation unit, wherein,

the azeotropic distillation tower 1 is used for azeotropic distillation of methanol and crude ethanol containing oxide impurities to obtain an azeotrope and purified ethanol;

the extraction rectifying tower 2 is communicated with the azeotropic rectifying tower 1 and is used for carrying out extraction rectification on the azeotrope and water to obtain oxide impurities and a methanol-containing aqueous solution;

the separation unit is communicated with the extractive distillation tower 2 and is used for separating the methanol-containing aqueous solution to obtain recovered methanol and recovered water;

preferably, the separation unit is communicated with the azeotropic distillation tower 1 and the extractive distillation tower 2, and is used for returning the recovered methanol to the azeotropic distillation tower 1 and returning the recovered water to the extractive distillation tower 2.

According to a specific embodiment, with reference to FIG. 1, the method for purifying ethanol from aqueous phase product from Fischer-Tropsch synthesis of the invention can be used in the device for purifying ethanol from aqueous phase product from Fischer-Tropsch synthesis of the invention, and specifically comprises the following steps:

(a) feeding methanol and crude ethanol containing oxide impurities from Fischer-Tropsch synthesis into an azeotropic distillation tower 1, wherein the methanol is introduced from the middle upper part of the azeotropic distillation tower 1, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower 1; controlling the weight ratio of methanol to crude ethanol, the reflux ratio of the azeotropic distillation tower 1, the operating temperature and pressure at the top of the tower and at the bottom of the tower, and the like, performing azeotropic distillation to obtain an azeotrope formed by the methanol and the oxide impurities at the top of the tower and obtain purified ethanol at the bottom of the tower;

(b) feeding water and the azeotrope obtained in the step (a) into an extractive distillation tower 2, wherein the water is introduced from the middle upper part of the extractive distillation tower 2, and the azeotrope is introduced from the middle part of the extractive distillation tower 2; and controlling the weight ratio of water to the azeotrope, the tower top, the operating temperature, the operating pressure and other conditions, performing extractive distillation to obtain oxide impurities at the tower top and aqueous solution containing methanol at the tower bottom, and separating the aqueous solution containing methanol to obtain recovered methanol and recovered water.

The present invention will be described in detail below by way of examples.

Example 1

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.2:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; wherein the reflux ratio of the azeotropic distillation tower is 1.35; the operation pressure at the top of the azeotropic distillation tower is 101.5kPa, the temperature at the top of the azeotropic distillation tower is 74.6 ℃, and the temperature at the bottom of the azeotropic distillation tower is 84.3 ℃; the azeotropic mixture of methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the purified ethanol with the purity of more than 99.9 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 90%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 0.75; the operation pressure of the top of the extraction rectifying tower is 102 kPa; the temperature at the top of the tower is 78.5 ℃, and the temperature at the bottom of the tower is 95.3 ℃; the composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 4.5 wt%: 47.75 wt%: and (3) recovering 47.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Example 2

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 40, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.4:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 90 wt% of 2-butanone: 5 wt%: 5 wt%; the reflux ratio of the azeotropic distillation tower is 1.5; the operating pressure at the top of the azeotropic distillation column was 102.5kPa, the temperature at the top of the column was 75.5 ℃ and the temperature at the bottom of the column was 86.1 ℃. The azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the purified ethanol with the purity of more than 99.9 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 90.5%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 45, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 1.5:1, and the reflux ratio of the extraction and rectification tower is 0.85; the operation pressure of the top of the extraction rectifying tower is 102.5 kPa; the temperature at the top of the column was 78.7 ℃ and the temperature at the bottom of the column was 95.4 ℃. The composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 7.5 wt%: 46.25 wt%: and (3) recovering 46.25 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Example 3

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 30, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.15:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 98 wt% of 2-butanone: 1 wt%: 1 wt%; the reflux ratio of the azeotropic distillation tower is 1.65; the operating pressure at the top of the azeotropic distillation column was 103.5kPa, the temperature at the top of the column was 74.8 ℃ and the temperature at the bottom of the column was 85.4 ℃. The azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the tower top, the purified ethanol with the purity of more than 99.9 wt% is obtained at the tower bottom, and the recovery rate of the ethanol is 91%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 55, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 1.15; the operation pressure at the top of the extraction rectification tower is 103.5 kPa; the temperature at the top of the column was 78.9 ℃ and the temperature at the bottom of the column was 96.7 ℃. The composition obtained at the top of the tower is: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as byproducts, returning the methanol-containing water solution at the tower bottom to the mixed alcohol separation process to obtain recovered water and recovered methanol, wherein the recovered methanol is recycled for azeotropic distillation, and the recovered water is recycled for extracting methanol.

Example 4

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 30, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.15:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 98 wt% of 2-butanone: 1 wt%: 1 wt%; the reflux ratio of the azeotropic distillation tower is 0.35; the operating pressure at the top of the azeotropic distillation column was 103.5kPa, the temperature at the top of the column was 74.8 ℃ and the temperature at the bottom of the column was 85.4 ℃. The azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the ethanol with the purity of about 98.5 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 90.6%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 10,

wherein, water is introduced from the middle upper part of the extraction and rectification tower, and the azeotrope is introduced from the middle part of the extraction and rectification tower; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 1.15; the operation pressure at the top of the extraction rectifying tower is 103.5 kPa; the temperature at the top of the column was 78.9 ℃ and the temperature at the bottom of the column was 96.7 ℃. The composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, wherein the recovered methanol is recycled for azeotropic distillation, and the recovered water is recycled for extracting methanol.

The water solution containing methanol at the bottom of the tower contains 0.5 percent of ethanol and 0.75 percent of 2-butanone. The separation effect of the extraction and the rectification is reduced.

Example 5

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.2:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; wherein the reflux ratio of the azeotropic distillation tower is 1.35; the operating pressure at the top of the azeotropic distillation tower is 120kPa, the temperature at the top of the azeotropic distillation tower is 72 ℃, and the temperature at the bottom of the azeotropic distillation tower is 95 ℃; the azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the purified ethanol with the purity of more than 99.8 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 89%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 0.75; the operation pressure of the top of the extraction rectifying tower is 102 kPa; the temperature at the top of the tower is 78.5 ℃, and the temperature at the bottom of the tower is 95.3 ℃; the composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Example 6

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.05:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; wherein the reflux ratio of the azeotropic distillation tower is 1.35; the operation pressure at the top of the azeotropic distillation tower is 101.5kPa, the temperature at the top of the azeotropic distillation tower is 74.6 ℃, and the temperature at the bottom of the azeotropic distillation tower is 84.3 ℃; the azeotropic mixture of methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the purified ethanol with the purity of more than 99.5 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 88%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 0.75; the operation pressure of the top of the extraction rectifying tower is 102 kPa; the temperature at the top of the tower is 78.5 ℃, and the temperature at the bottom of the tower is 95.3 ℃; the composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Example 7

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.2:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; wherein the reflux ratio of the azeotropic distillation tower is 1.35; the operation pressure at the top of the azeotropic distillation tower is 101.5kPa, the temperature at the top of the azeotropic distillation tower is 74 ℃, and the temperature at the bottom of the azeotropic distillation tower is 84 ℃; the azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the tower top, the purified ethanol with the purity of more than 99.9 wt% is obtained at the tower bottom, and the recovery rate of the ethanol is 86%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 1:1, and the reflux ratio of the extraction and rectification tower is 0.75; the operation pressure of the top of the extraction rectifying tower is 115 kPa; the temperature at the top of the tower is 78 ℃, and the temperature at the bottom of the tower is 90 ℃; the tower top comprises the following components: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Example 8

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.15:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; wherein the reflux ratio of the azeotropic distillation tower is 1.35; the operation pressure at the top of the azeotropic distillation tower is 101.5kPa, the temperature at the top of the azeotropic distillation tower is 74.6 ℃, and the temperature at the bottom of the azeotropic distillation tower is 84.3 ℃; the azeotropic mixture of methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, purified ethanol with the purity of more than 99.9 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 87%.

(2) Feeding water and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the water is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of water to azeotrope is 0.5:1, and the reflux ratio of the extraction and rectification tower is 0.75; the operation pressure of the top of the extraction rectifying tower is 102 kPa; the temperature at the top of the tower is 78.5 ℃, and the temperature at the bottom of the tower is 95.3 ℃; the composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone 2.5 wt%: 48.75 wt%: and (3) recovering 48.75 wt% of light components as a byproduct, returning the methanol-containing aqueous solution at the bottom of the tower to the mixed alcohol separation process to obtain recovered water and recovered methanol, recycling the recovered methanol for azeotropic distillation, and recycling the recovered water for extracting methanol.

Comparative example

(1) Feeding crude ethanol and methanol from Fischer-Tropsch synthesis mixed alcohol separation into an azeotropic distillation tower, wherein the number of tower plates is 35, the methanol is introduced from the middle upper part of the azeotropic distillation tower, and the crude ethanol is introduced from the middle part of the azeotropic distillation tower for azeotropic distillation; wherein the weight ratio of the methanol to the crude ethanol is 0.2:1, and the crude ethanol comprises the following components: ethanol: ethyl acetate: 95 wt% of 2-butanone: 2.5 wt%: 2.5 wt%; the reflux ratio of the azeotropic distillation tower is 1.35; the operating pressure at the top of the azeotropic distillation tower is 101.5kPa, the temperature at the top of the tower is 74.6 ℃, and the temperature at the bottom of the tower is 84.3 ℃. The azeotrope formed by methanol, ethyl acetate and 2-butanone is obtained at the top of the tower, the purified ethanol with the purity of more than 99.9 wt% is obtained at the bottom of the tower, and the recovery rate of the ethanol is 85.5%.

(2) Feeding ethylene glycol and the azeotrope obtained in the step (1) into an extractive distillation tower, wherein the number of tower plates is 50, the ethylene glycol is introduced from the middle upper part of the extractive distillation tower, and the azeotrope is introduced from the middle part of the extractive distillation tower for extractive distillation; the weight ratio of the ethylene glycol to the azeotrope is 2:1, and the reflux ratio of the extractive distillation tower is 1.05; the operation pressure at the top of the extraction rectifying tower is 101.5 kPa; the temperature at the top of the column was 78.6 ℃ and the temperature at the bottom of the column was 154.5 ℃. The composition obtained at the tower top is as follows: ethanol: ethyl acetate: 2-butanone: methanol 3.5 wt%: 48.75 wt%: 45.75 wt%: 2.0 wt% of light components, recovered as by-products, with increased loss of ethanol and methanol. The glycol-containing solution at the bottom of the tower contains 0.25% of ethanol and 0.35% of 2-butanone. The effect of extraction, rectification and separation is reduced.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.