阅读说明：本技术 混醇分离系统以及混醇分离方法 (Mixed alcohol separation system and mixed alcohol separation method ) 是由 齐静 雍晓静 关翀 刘琰 金政伟 张伟 于 2020-12-25 设计创作，主要内容包括：本发明涉及分离提纯技术领域,公开了一种混醇分离系统以及混醇分离方法,混醇分离系统包括初分单元和分离单元,初分单元设置为能够接收含有混醇的水溶液并对该水溶液进行初步分离以分别得到甲醇、含有碳原子数大于等于2且小于等于3的轻醇的轻混醇分离气以及含有重醇的重醇分离液；分离单元设置于所述初分单元的下游,分离单元设置为能够接收由初分单元排出的轻混醇分离气并分离出轻混醇分离气所含有的各个轻醇。该混醇分离系统能够将含有混醇的水溶液所含有的重醇和各个轻醇彼此分离开来,实现了废料的回收利用,降低了能源浪费。利用上述混醇分离方法能够将水溶液中的重醇和各个轻醇彼此相分离开,实现了对含有混醇的水溶液的回收利用。(The invention relates to the technical field of separation and purification, and discloses a mixed alcohol separation system and a mixed alcohol separation method, wherein the mixed alcohol separation system comprises a primary separation unit and a separation unit, the primary separation unit is arranged to be capable of receiving an aqueous solution containing mixed alcohol and carrying out primary separation on the aqueous solution to respectively obtain methanol, light mixed alcohol separation gas containing light alcohol with the carbon atom number being more than or equal to 2 and less than or equal to 3 and heavy alcohol separation liquid containing heavy alcohol; the separation unit is arranged at the downstream of the primary separation unit, and the separation unit is arranged to be capable of receiving the light mixed alcohol separation gas discharged by the primary separation unit and separating each light alcohol contained in the light mixed alcohol separation gas. The mixed alcohol separation system can separate heavy alcohol and light alcohol contained in the mixed alcohol-containing aqueous solution from each other, thereby realizing the recycling of waste materials and reducing the energy waste. The heavy alcohol and each light alcohol in the aqueous solution can be separated from each other by the mixed alcohol separation method, and the recycling of the aqueous solution containing the mixed alcohol is realized.)

1. A mixed alcohol separation system, characterized in that the mixed alcohol separation system (10) comprises:

a preliminary separation unit (12), wherein the preliminary separation unit (12) is arranged to receive an aqueous solution containing mixed alcohol and perform preliminary separation on the aqueous solution to obtain methanol, a light mixed alcohol separation gas containing light alcohol with the carbon number being more than or equal to 2 and less than or equal to 3, and a heavy alcohol separation liquid containing heavy alcohol; and

a separation unit (14), wherein the separation unit (14) is arranged at the downstream of the primary separation unit (12), and the separation unit (14) is arranged to be capable of receiving the light mixed alcohol separation gas discharged by the primary separation unit (12) and separating out each light alcohol contained in the light mixed alcohol separation gas.

2. The mixed alcohol separation system of claim 1, wherein the separation unit (14) comprises:

a first rectifying column (14a), wherein the first rectifying column (14a) is arranged at the downstream of the primary separation unit (12), and the first rectifying column (14a) is arranged to receive the light mixed alcohol separation gas discharged from the primary separation unit (12) and separate ethanol in the light mixed alcohol separation gas to obtain a primary separation liquid; and

a second rectification column (14b), the second rectification column (14b) is arranged at the downstream of the first rectification column (14a), the second rectification column (14b) is arranged to receive the primary separation liquid discharged by the first rectification column (14a) and separate the propanol in the primary separation liquid.

3. The mixed alcohol separation system according to claim 2, wherein the separation unit (14) includes a propanol dehydrating tower (14c), the propanol dehydrating tower (14c) being disposed downstream of the second rectification tower (14b), the propanol dehydrating tower (14c) being disposed so as to be capable of receiving the propanol discharged from the second rectification tower (14b) and dehydrating the propanol.

4. The mixed alcohol separation system according to claim 1, wherein the mixed alcohol separation system (10) comprises a methanol rectification column (16), the methanol rectification column (16) is arranged at the downstream of the primary separation unit (12), and the methanol rectification column (16) is arranged to receive the methanol discharged from the primary separation unit (12) and carry out rectification purification on the methanol; and/or

Mix alcohol piece-rate system (10) including preheating unit (11), preheating unit (11) set up in the upper reaches of elementary cell (12), preheating unit (11) set up to can with aqueous solution heat to the temperature after presetting will the heating aqueous solution is leading-in elementary cell (12).

5. The mixed alcohol separation system according to any one of claims 1 to 4, wherein the mixed alcohol separation system (10) includes a heavy alcohol refining unit (18), the heavy alcohol refining unit (18) is disposed downstream of the primary separation unit (12), and the heavy alcohol refining unit (18) is disposed so as to be capable of receiving the heavy alcohol-containing heavy alcohol separated liquid discharged from the primary separation unit (12) and separating out the heavy alcohol in the heavy alcohol separated liquid.

6. The mixed alcohol separation system of claim 5, wherein the heavy alcohol refining unit (18) comprises:

a first phase separator (18c), said first phase separator (18c) being disposed downstream of said preliminary separation unit (12), said first phase separator (18c) being configured to receive a heavy alcohol-containing heavy alcohol-separated liquid discharged from said preliminary separation unit (12) and to subject said heavy alcohol-separated liquid to a phase separation process to obtain a primary oil phase and a primary aqueous phase; and

a heavy alcohol refining column (18b), the heavy alcohol refining column (18b) being disposed downstream of the first phase separator (18c), the heavy alcohol refining column (18b) being disposed so as to be capable of receiving a primary oil phase discharged from the first phase separator (18c) and separating heavy alcohol in the primary oil phase.

7. The mixed alcohol separation system of claim 6, wherein the heavy alcohol refining unit (18) comprises:

a heavy alcohol dehydration column (18a), the heavy alcohol dehydration column (18a) being configured to receive the primary aqueous phase discharged from the first phase separator (18c) and to dehydrate the primary aqueous phase and obtain a first vapor containing heavy alcohols; and

a second phase separator (18d), the second phase separator (18d) being configured to receive the first vapor discharged from the heavy alcohol dehydration column (18a) and subject the first vapor to a phase separation process to obtain a secondary aqueous phase and a secondary oil phase, the second phase separator (18d) introducing the secondary oil phase to the heavy alcohol refining column (18 b).

8. The mixed alcohol separation system of claim 7, wherein the heavy alcohol finishing column (18b) separates the primary oil phase and produces a second vapor;

the heavy alcohol refining unit (18) comprises a third phase separator (18e), the third phase separator (18e) is arranged at the downstream of the heavy alcohol refining tower (18b), the third phase separator (18e) is arranged to receive the second steam discharged by the heavy alcohol refining tower (18b) and carry out phase separation treatment on the second steam to obtain a third water phase and a third oil phase, and the third phase separator (18e) returns the third oil phase to the heavy alcohol refining tower (18 b).

9. A mixed alcohol separation method is characterized by comprising the following steps:

step S10: receiving an aqueous solution containing mixed alcohol and carrying out primary separation on the aqueous solution to respectively obtain methanol, a light mixed alcohol separation gas containing light alcohol with the carbon atom number of more than or equal to 2 and less than or equal to 3 and a heavy alcohol separation liquid containing heavy alcohol;

step S20: and separating the light mixed alcohol separation gas to respectively obtain each light alcohol contained in the light mixed alcohol separation gas.

10. The mixed alcohol separation method according to claim 9, wherein in the step S10, the aqueous solution is subjected to a dividing wall rectification to achieve a preliminary separation of the aqueous solution; preferably, the temperature of the divided wall rectification is set to be 60-100 ℃, and the reflux ratio of the divided wall rectification is set to be 1-4.

11. The mixed alcohol separation method according to claim 9, wherein the step S20 includes:

s20 a: separating out ethanol contained in the light mixed alcohol separation gas and obtaining primary separation liquid;

s20 b: separating out propanol contained in the first-stage separation liquid.

12. The mixed alcohol separation method according to claim 9, wherein in the step S20a, the light mixed alcohol separation gas is subjected to extractive distillation to separate ethanol contained in the light mixed alcohol separation gas, preferably, the temperature of the extractive distillation is set to 20 ℃ to 30 ℃, and the reflux ratio of the extractive distillation is set to 1 to 10.

13. The mixed alcohol separation method according to claim 9, wherein in the step S20b, the first separated liquid is subjected to extractive distillation to separate propanol contained in the first separated liquid, preferably, the temperature of the extractive distillation is set to 20 ℃ to 30 ℃, and the reflux ratio of the extractive distillation is set to 1 to 10.

14. The mixed alcohol separation method according to any one of claims 9 to 13, wherein the mixed alcohol separation method comprises:

step S30 a: performing phase separation treatment on the heavy alcohol separation liquid separated in the step S10 to obtain a first-order oil phase and a first-order water phase;

step S30 b: rectifying the first oil phase to obtain heavy alcohol.

15. The mixed alcohol separation method according to claim 14, wherein the mixed alcohol separation method comprises:

step S30 c: subjecting the primary aqueous phase to a dehydration treatment to obtain a first vapor containing heavy alcohols;

step S30 d: the first steam is subjected to a phase separation treatment to obtain a secondary aqueous phase and a secondary oil phase, and the secondary oil phase is returned to the step S30b for a rectification treatment.

16. The mixed alcohol separation method according to claim 15, wherein in the step S30b, the temperature during rectification is set to 100 ℃ to 105 ℃, and the reflux ratio during rectification is set to 1 to 8; and/or

In step S30c, the dehydration temperature is set to 100-103 ℃, and the reflux ratio of dehydration is set to 1-10.

Technical Field

The invention relates to the technical field of separation and purification, in particular to a mixed alcohol separation system and a mixed alcohol separation method.

Background

Fischer-Tropsch synthesis (also known as Fischer-Tropsch synthesis) is a process in which synthesis gas (a mixture of carbon monoxide and hydrogen) is used as a raw material to synthesize liquid hydrocarbons or hydrocarbons (hydrocarbons) in the presence of a catalyst under appropriate conditions.

The synthetic water produced by the Fischer-Tropsch synthesis can be generally called Fischer-Tropsch synthetic water, and the Fischer-Tropsch synthetic water generally contains more alcohol substances such as methanol, ethanol, n-propanol, n-butanol and n-pentanol, wherein the methanol, the ethanol and the n-propanol are generally called light alcohols, and the n-butanol and the n-pentanol are called heavy alcohols.

In order to realize the recycling of alcohol substances in the Fischer-Tropsch synthesis water, light alcohol and heavy alcohol in the Fischer-Tropsch synthesis water need to be separated.

Disclosure of Invention

The purpose of the present invention is to provide a mixed alcohol separation system capable of separating heavy alcohols and light alcohols contained in an aqueous solution containing mixed alcohols from each other.

In order to achieve the above object, an aspect of the present invention provides a mixed alcohol separation system including:

a preliminary separation unit configured to receive an aqueous solution containing mixed alcohol and preliminarily separate the aqueous solution to obtain methanol, a light mixed alcohol separation gas containing light alcohol having 2 or more and 3 or less carbon atoms, and a heavy alcohol separation liquid containing heavy alcohol, respectively; and

and the separation unit is arranged at the downstream of the primary separation unit and is capable of receiving the light mixed alcohol separated gas discharged by the primary separation unit and separating out each light alcohol contained in the light mixed alcohol separated gas.

According to the technical scheme, the initial separation unit and the separation unit are arranged, so that the light mixed alcohol and the heavy alcohol in the water solution containing the mixed alcohol can be separated firstly, and then each light alcohol contained in the light mixed alcohol can be separated, so that the heavy alcohol and each light alcohol in the water solution containing the mixed alcohol can be separated from each other, the water solution containing the mixed alcohol can be recycled, and the energy waste is reduced.

Preferably, the separation unit comprises:

the first rectifying tower is arranged at the downstream of the primary separation unit and can receive the light mixed alcohol separation gas discharged by the primary separation unit and separate ethanol in the light mixed alcohol separation gas to obtain primary separation liquid; and

and the second rectifying tower is arranged at the downstream of the first rectifying tower and can receive the primary separating liquid discharged by the first rectifying tower and separate the propanol in the primary separating liquid.

Preferably, the separation unit includes a propanol dehydrating tower disposed downstream of the second rectification tower, the propanol dehydrating tower being configured to receive the propanol discharged from the second rectification tower and dehydrate the propanol.

Preferably, the mixed alcohol separation system comprises a methanol rectifying tower, the methanol rectifying tower is arranged at the downstream of the primary separation unit, and the methanol rectifying tower is arranged to be capable of receiving the methanol discharged by the primary separation unit and rectifying and purifying the methanol; and/or

Mix the mellow wine piece-rate system and include preheating unit, preheating unit set up in the upper reaches of elementary branch unit, preheating unit set up to can with aqueous solution heat to after the preset temperature with the heating aqueous solution is leading-in elementary branch unit.

Preferably, the mixed alcohol separation system includes a heavy alcohol refining unit disposed downstream of the preliminary separation unit, the heavy alcohol refining unit being configured to be able to receive the heavy alcohol separation liquid containing the heavy alcohol discharged from the preliminary separation unit and to separate out the heavy alcohol in the heavy alcohol separation liquid.

Preferably, the heavy alcohol refining unit comprises:

the first phase separator is arranged at the downstream of the primary separation unit and is used for receiving heavy alcohol separation liquid containing heavy alcohol discharged by the primary separation unit and carrying out phase separation treatment on the heavy alcohol separation liquid to obtain a primary oil phase and a primary water phase; and

a heavy alcohol refining column disposed downstream of the first phase separator, the heavy alcohol refining column configured to receive a primary oil phase discharged by the first phase separator and separate heavy alcohol from the primary oil phase.

Preferably, the heavy alcohol refining unit comprises:

a heavy alcohol dehydration column configured to receive the primary aqueous phase discharged from the first phase separator and to dehydrate the primary aqueous phase to obtain a first vapor containing heavy alcohol; and

a second phase separator configured to receive the first steam discharged from the heavy alcohol dehydration column and perform phase separation processing on the first steam to obtain a secondary aqueous phase and a secondary oil phase, the second phase separator introducing the secondary oil phase into the heavy alcohol refining column.

Preferably, the heavy alcohol refining column separates the primary oil phase and produces a second vapor;

the heavy alcohol refining unit comprises a third phase separator, the third phase separator is arranged at the downstream of the heavy alcohol refining tower, the third phase separator is arranged to receive second steam discharged by the heavy alcohol refining tower and carry out phase separation treatment on the second steam to obtain a third-stage water phase and a third-stage oil phase, and the third phase separator returns the third-stage oil phase to the heavy alcohol refining tower.

The second aspect of the present invention provides a mixed alcohol separation method, including:

step S10: receiving an aqueous solution containing mixed alcohol and carrying out primary separation on the aqueous solution to respectively obtain methanol, a light mixed alcohol separation gas containing light alcohol with the carbon atom number of more than or equal to 2 and less than or equal to 3 and a heavy alcohol separation liquid containing heavy alcohol;

step S20: and separating the light mixed alcohol separation gas to respectively obtain each light alcohol contained in the light mixed alcohol separation gas.

The mixed alcohol separation method provided by the invention can separate the heavy alcohol and each light alcohol in the mixed alcohol-containing aqueous solution from each other, thereby realizing the recycling of the mixed alcohol-containing aqueous solution and reducing the energy waste.

Preferably, in the step S10, the aqueous solution is subjected to a dividing wall rectification to achieve a preliminary separation of the aqueous solution.

Preferably, the temperature of the divided wall rectification is set to be 60-100 ℃, and the reflux ratio of the divided wall rectification is set to be 1-4.

Preferably, the step S20 includes:

s20 a: separating out ethanol contained in the light mixed alcohol separation gas and obtaining primary separation liquid;

s20 b: separating out propanol contained in the first-stage separation liquid.

Preferably, in the step S20a, the light mixed alcohol separation gas is subjected to extractive distillation to separate ethanol contained in the light mixed alcohol separation gas.

Preferably, the temperature of the extractive distillation is set to be 20-30 ℃, and the reflux ratio of the extractive distillation is set to be 1-10.

Preferably, in the step S20b, the first separation liquid is subjected to extractive distillation to separate propanol contained in the first separation liquid.

Preferably, the temperature of the extractive distillation is set to be 20-30 ℃, and the reflux ratio of the extractive distillation is set to be 1-10.

Preferably, the mixed alcohol separation method comprises:

step S30 a: performing phase separation treatment on the heavy alcohol separation liquid separated in the step S10 to obtain a first-order oil phase and a first-order water phase;

step S30 b: rectifying the first oil phase to obtain heavy alcohol.

Preferably, the mixed alcohol separation method comprises:

step S30 c: subjecting the primary aqueous phase to a dehydration treatment to obtain a first vapor containing heavy alcohols;

step S30 d: the first steam is subjected to a phase separation treatment to obtain a secondary aqueous phase and a secondary oil phase, and the secondary oil phase is returned to the step S30b for a rectification treatment.

Preferably, in the step S30b, the temperature during rectification is set to be 100-105 ℃, and the reflux ratio during rectification is set to be 1-8; and/or

In step S30c, the dehydration temperature is set to 100-103 ℃, and the reflux ratio of dehydration is set to 1-10.

Drawings

Fig. 1 is a schematic view of the overall structure of a mixed alcohol separation system according to a preferred embodiment of the present invention.

Description of the reference numerals

10-mixed alcohol separation system; 11-a preheating unit; 110-a heat exchanger; 12-primary division unit; 120-dividing wall rectifying tower; 14-a separation unit; 14 a-a first rectification column; 14 b-a second rectification column; 14 c-propanol dehydration column; 14 d-a solvent recovery column; a 16-methanol rectification column; 16 a-methanol reflux tank; 16 b-a methanol collection tank; an 18-heavy alcohol refining unit; 18 a-a heavy alcohol dehydration column; 18 b-a heavy alcohol finishing column; 18 c-a first phase splitter; 18 d-a second phase splitter; 18 e-third phase splitter.

Detailed Description

In the present invention, the use of directional terms such as "upper, lower, left and right" in the absence of a contrary explanation generally means that the directions shown in the drawings and the practical application are considered to be the same, and "inner and outer" mean the inner and outer of the outline of the component.

The invention provides a mixed alcohol separation system, as shown in fig. 1, a mixed alcohol separation system 10 comprises an initial separation unit 12, the initial separation unit 12 is configured to receive an aqueous solution containing mixed alcohol and perform initial separation on the aqueous solution to respectively obtain methanol, light mixed alcohol separation gas containing light alcohol with the carbon atom number being more than or equal to 2 and less than or equal to 3, and heavy alcohol separation liquid containing heavy alcohol, it can be understood that the aqueous solution containing mixed alcohol can be separated into methanol, light mixed alcohol separation gas containing light alcohol with the carbon atom number being more than or equal to 2 and less than or equal to 3, and heavy alcohol separation liquid containing heavy alcohol after entering the initial separation unit 12, wherein Fischer-Tropsch synthesis water can be used as the aqueous solution containing mixed alcohol to be introduced into the initial separation unit 12 for separation, the light mixed alcohol separation gas can substantially contain ethanol and propanol, the heavy alcohol separation liquid can contain heavy alcohol with the carbon atom number being more than or equal to 4, at the same time, the compound also contains acid substances such as acetic acid and propionic acid, and also contains a small amount of acetaldehyde and acetone, and trace butyraldehyde, methyl acetate, ethyl acetate, 2-pentanone, n-octanol, isobutyric acid, n-heptanoic acid and the like; the mixed alcohol separation system 10 further includes a separation unit 14, the separation unit 14 is disposed downstream of the primary separation unit 12, and the separation unit 14 is configured to receive the light mixed alcohol separated gas discharged from the primary separation unit 12 and separate out each light alcohol contained in the light mixed alcohol separated gas, that is, to separate out ethanol and propanol contained in the light mixed alcohol separated gas. By providing the preliminary separation unit 12 and the separation unit 14, the light mixed alcohol and the heavy alcohol in the aqueous solution containing the mixed alcohol can be separated first, and then each light alcohol contained in the light mixed alcohol can be separated, so that the heavy alcohol and each light alcohol in the aqueous solution containing the mixed alcohol can be separated from each other, the aqueous solution containing the mixed alcohol can be recycled, and the energy waste can be reduced. The aqueous solution containing the mixed alcohol may contain light alcohols such as methanol, ethanol and propanol, and may further contain heavy alcohols having 4 or more carbon atoms, and further, the aqueous solution containing the mixed alcohol may contain acids such as acetic acid and propionic acid, and a small amount of acetaldehyde, acetone, and a small amount of butylaldehyde, methyl acetate, ethyl acetate, 2-pentanone, n-octanol, isobutyric acid, n-heptanoic acid, and the like. Furthermore, it should be noted that the mixed alcohol separation system 10 is particularly suitable for separating the light alcohols and the heavy alcohols contained in Fischer-Tropsch synthesis water, wherein the Fischer-Tropsch synthesis water may contain the following components in percentage by weight: water: 20% -40%, methanol: 5% -15%, ethanol: 25% -45%, propanol: 3% -10%, butanol: 3% -7%, pentanol: 1% -5% of other components, and 3% -8% of other components, wherein the other components comprise acid substances such as acetic acid, propionic acid, small amounts of acetaldehyde, acetone and butyraldehyde, methyl acetate, ethyl acetate, 2-pentanone, n-octanol, isobutyric acid, n-heptanoic acid and the like. In addition, the mixed alcohol separation system 10 has a compact overall structure, occupies a small space, and is convenient to popularize and apply in a limited space.

Among them, the preliminary separation unit 12 may include a divided wall rectifying column 120, so that it is possible to facilitate separation of each of the light alcohol and the heavy alcohol contained in the aqueous solution containing the mixed alcohol, while reducing the content of the acid substance, particularly the organic acid, contained in the separated heavy alcohol. The dividing wall rectifying tower 120 is provided with a dividing wall rectifying tower inlet for water solution containing mixed alcohol to enter, a first light outlet for methanol to be discharged, a second light outlet for light mixed alcohol separated gas to be discharged, and a dividing wall rectifying tower heavy outlet for heavy alcohol separated liquid containing heavy alcohol to be discharged, wherein the dividing wall rectifying tower inlet can be arranged on the side wall of the dividing wall rectifying tower 120, the first light outlet can be arranged on the top wall of the dividing wall rectifying tower 120, the second light outlet can be arranged on the side wall of the dividing wall rectifying tower 120, and the heavy alcohol separated liquid can be arranged on the bottom wall of the dividing wall rectifying tower 120.

Taking Fischer-Tropsch synthesis water as an example, a first light weight discharge port discharges a first light weight which contains 50-60 wt% of methanol and water; and a second light discharge port discharges light mixed alcohol separation gas, and the light mixed alcohol separation gas contains the following components in percentage by weight: ethanol: 60% -75%, n-propanol: 10% -20%, water: 10% -20%; a heavy alcohol separation liquid containing heavy alcohol is discharged from a heavy discharge port of the dividing wall rectifying tower, and the heavy alcohol separation liquid contains the following components in percentage by weight: alcohol having 4 or more carbon atoms: 10% -20%, ethanol: 0.1% -0.5%, n-propanol: 1% -2%, water: 70 to 80 percent.

As shown in fig. 1, separation unit 14 may include a first rectification column 14a and a second rectification column 14 b.

The first rectifying tower 14a may be disposed downstream of the preliminary separation unit 12, the first rectifying tower 14a may be configured to receive the light mixed alcohol separated gas discharged from the preliminary separation unit 12 and separate ethanol from the light mixed alcohol separated gas to obtain a primary separated liquid, and the primary separated liquid may be obtained after ethanol contained in the light mixed alcohol separated gas is separated; it can be understood that the first rectification tower 14a may be provided with a first rectification tower inlet for the light mixed alcohol separation gas to enter, an ethanol discharge port for the ethanol to be discharged, and a first rectification tower heavy discharge port for the primary separation liquid to be discharged, wherein the first rectification tower inlet may be disposed on a side wall of the first rectification tower 14a, the ethanol discharge port may be disposed on a top wall of the first rectification tower 14a, and the first rectification tower heavy discharge port may be disposed on a bottom wall of the first rectification tower 14 a. In order to separate out the ethanol better, the ethanol can be separated out by adopting an extraction and rectification mode. The first rectification column 14a may be provided with a first extractant inlet for an extractant to enter, and the first extractant inlet may be disposed above the first rectification column inlet. Wherein, the extractant can be cyclohexane and/or ethylene glycol.

The second rectifying tower 14b can be arranged at the downstream of the first rectifying tower 14a, the second rectifying tower 14b can be arranged to receive the primary separation liquid discharged from the first rectifying tower 14a and separate propanol in the primary separation liquid, a secondary separation liquid can be obtained after the propanol contained in the primary separation liquid is separated, and when the extractant is selected for carrying out extractive distillation on the primary separation liquid, the secondary separation liquid contains more extractants; the second rectifying tower 14b may be provided with a second rectifying tower inlet for the first-stage separated liquid to enter, a propanol outlet for the propanol to be discharged, and a second rectifying tower heavy outlet for the second-stage separated liquid to be discharged, wherein the second rectifying tower inlet may be disposed on a side wall of the second rectifying tower 14b, the propanol outlet may be disposed on a top wall of the second rectifying tower 14b, and the second rectifying tower heavy outlet may be disposed on a bottom wall of the second rectifying tower 14 b. For better separation of the propanol, the propanol can be separated by means of extractive distillation. The second rectification column 14b may be provided with a second extractant inlet for the extractant to enter, and the second extractant inlet may be disposed above the second rectification column inlet. The extractant may be cyclohexane and/or ethylene glycol. The part of the propanol discharged from the propanol discharge port may be used as a reflux liquid, and the part of the propanol discharged from the propanol discharge port may be discharged into the propanol dehydrating tower 14c to be dehydrated.

In addition, the separation unit 14 may include a propanol dehydrating tower 14c, the propanol dehydrating tower 14c may be disposed downstream of the second rectification tower 14b, and the propanol dehydrating tower 14c may be disposed to receive the propanol discharged from the second rectification tower 14b and dehydrate the propanol, it being understood that the propanol discharged from the second rectification tower 14b contains moisture (about 5 wt% of water), and the propanol may be dehydrated by the propanol dehydrating tower 14c to obtain anhydrous propanol, wherein the propanol dehydrating tower 14c may be a rectification tower. The propanol dehydrating tower 14c may be provided with a raw material inlet for the entry of propanol, a propanol dehydrating tower light outlet for the discharge of water-containing propanol gas, and a propanol dehydrating tower heavy outlet for the discharge of anhydrous propanol, respectively, wherein: the raw material inlet can be arranged on the side wall of the propanol dehydrating tower 14c, the light outlet of the propanol dehydrating tower can be arranged on the top wall of the propanol dehydrating tower 14c, and the heavy outlet of the propanol dehydrating tower can be arranged on the bottom wall of the propanol dehydrating tower 14 c. Part of the propanol gas discharged from the light-weight discharge port of the propanol dehydrating tower may be used as a reflux, and part of the propanol gas discharged from the light-weight discharge port of the propanol dehydrating tower may be returned to the second rectifying tower 14 b. Wherein, the water content of the propanol gas discharged from the light discharge port of the propanol dehydrating tower is 25 wt%.

In order to recycle the extractant for reducing energy waste, a solvent recovery column 14d may be provided. The second-stage separation liquid discharged from the heavy discharge port of the second rectifying tower can be discharged into the solvent recovery tower 14d, the solvent recovery tower 14d can separate water and an extracting agent in the second-stage separation liquid, wherein the extracting agent can be discharged from the bottom of the solvent recovery tower 14d and can be used as the extracting agent in the extractive rectification operation of the first rectifying tower 14a and the second rectifying tower 14b respectively, so that the material usage amount is greatly reduced, and the recovery cost is reduced. The solvent recovery column 14d can be a rectification column.

In order to increase the application range of methanol, as shown in fig. 1, a methanol rectification column 16 may be provided, the methanol rectification column 16 may be disposed downstream of the preliminary separation unit 12, and the methanol rectification column 16 may be configured to receive methanol discharged from the preliminary separation unit 12 and perform rectification purification on the methanol. The methanol rectifying tower 16 can be provided with a rectifying tower inlet for methanol to enter, a methanol rectifying tower light outlet for discharging rectified and purified methanol, and a methanol rectifying tower heavy outlet for discharging tower bottom liquid containing ethanol generated during rectifying and purifying methanol, wherein the tower bottom liquid discharged from the methanol rectifying tower heavy outlet can be discharged back to the primary separation unit 12, the rectified and purified methanol from the methanol rectifying tower light outlet can be cooled by a cooler and then enters the methanol reflux tank 16a, part of methanol in the methanol reflux tank 16a can be used as reflux liquid, and part of methanol in the methanol reflux tank 16a can be discharged into the methanol collection tank 16b for collection. The methanol rectification column 16 may be a packed column.

In order to ensure that the preliminary separation unit 12 performs a better separation operation, a preheating unit 11 may be provided, the preheating unit 11 may be provided upstream of the preliminary separation unit 12, and the preheating unit 11 may be provided to heat the aqueous solution to a predetermined temperature and then introduce the heated aqueous solution into the preliminary separation unit 12, and it will be understood that the aqueous solution containing the mixed alcohol is heated and then discharged into the preliminary separation unit 12 to perform a separation operation. The preheating unit 11 may include a heat exchanger 110, that is, the heat exchanger 110 may be used to heat the aqueous solution containing the mixed alcohol. Preferably, a plurality of heat exchangers 110 may be provided in series to sequentially heat the aqueous solution containing the mixed alcohol, and thus, by providing a plurality of heat exchangers 110, heating efficiency and heating effect may be improved.

As shown in fig. 1, a heavy alcohol refining unit 18 may be provided, the heavy alcohol refining unit 18 may be provided downstream of the preliminary separation unit 12, and the heavy alcohol refining unit 18 may be provided to be able to receive the heavy alcohol-containing heavy alcohol separated liquid discharged from the preliminary separation unit 12 and separate out the heavy alcohol in the heavy alcohol separated liquid, so that the heavy alcohol can be recycled, and waste of materials can be reduced.

Among other things, the heavy alcohol refining unit 18 may include a first phase separator 18c and a heavy alcohol refining column 18 b.

The first phase separator 18c may be disposed downstream of the preliminary separation unit 12, and the first phase separator 18c may be disposed to receive the heavy alcohol separated liquid containing the heavy alcohol discharged from the preliminary separation unit 12 and perform a phase separation process on the heavy alcohol separated liquid to obtain a primary oil phase and a primary water phase. The first phase separator 18c may be provided with a first phase separator inlet through which a heavy alcohol separation liquid containing heavy alcohol enters, a first-stage oil phase outlet through which a first-stage oil phase is discharged, and a first-stage water phase outlet through which a first-stage water phase is discharged, wherein the first-stage oil phase outlet may be disposed at the top of the first phase separator 18c, and the first-stage water phase outlet may be disposed at the bottom of the first phase separator 18 c. The first phase separator 18c is provided to further improve the rectification effect of the heavy alcohol refining column 18 b.

The heavy alcohol refining column 18b may be disposed downstream of the first phase separator 18c, and the heavy alcohol refining column 18b may be disposed to be capable of receiving the first oil phase discharged from the first phase separator 18c and separating the heavy alcohol in the first oil phase. The heavy alcohol refining tower 18b may be provided with a heavy alcohol refining tower inlet through which the first-stage oil phase enters, a heavy alcohol discharge port through which the heavy alcohol is discharged, and a tower bottom liquid discharge port through which the tower bottom liquid generated after refining the first-stage oil phase is discharged, respectively. The heavy alcohol discharged from the heavy alcohol discharge port can be collected and utilized. The heavy alcohol refining column inlet may be in communication with the first oil phase discharge to receive the first oil phase. Wherein, the heavy alcohol refining tower 18b can be a dividing wall rectifying tower, so that the content of organic acid carried in the heavy alcohol obtained by rectifying can be further reduced by dividing wall rectifying the first-stage oil phase.

Heavy alcohol refining unit 18 may include a heavy alcohol dehydration column 18a and a second phase separator 18 d.

Heavy alcohol dehydration column 18a may be configured to receive the first aqueous phase discharged from first phase separator 18c and dehydrate the first aqueous phase to obtain a first vapor comprising heavy alcohols; the heavy alcohol dehydration tower 18a may be provided with a heavy alcohol dehydration tower inlet for the entry of the primary aqueous phase, a heavy alcohol dehydration tower light discharge port for the discharge of the first vapor, and a heavy alcohol dehydration tower heavy discharge port for the discharge of the bottom liquid, respectively, wherein: the inlet of the heavy alcohol dehydration tower can be communicated with the first-stage water phase discharge port. The bottom liquid discharge port may be connected to the heavy alcohol dehydration column 18a so as to discharge the bottom liquid produced by purifying the first-order oil phase into the heavy alcohol dehydration column 18a for dehydration, thereby further improving separation and recovery of the heavy alcohol separation liquid. Heavy alcohol dehydration column 18a may comprise a rectification column. It should be noted that the bottom liquid discharged from the bottom liquid discharge port contains most of the other components mentioned above.

The second phase separator 18d may be provided to receive the first steam discharged from the heavy alcohol dehydration column 18a and subject the first steam to a phase separation treatment to obtain a secondary aqueous phase and a secondary oil phase, and the second phase separator 18d may introduce the secondary oil phase into the heavy alcohol refining column 18 b. The second phase separator 18d may be provided with a second phase separator inlet for the first steam to enter, a second oil phase outlet for the second oil phase to be discharged, and a second water phase outlet for the second water phase to be discharged, wherein the second oil phase outlet may be disposed at the top of the second phase separator 18d, and the second water phase outlet may be disposed at the bottom of the second phase separator 18 d. The inlet of the second phase separator can be communicated with the light outlet of the heavy alcohol dehydration tower, the outlet of the secondary oil phase can be communicated with the heavy alcohol refining tower 18b, and the outlet of the secondary water phase can be communicated with the primary separation unit 12.

Therefore, by arranging the heavy alcohol dehydration tower 18a and the second phase separator 18d, the heavy alcohol and light alcohol such as ethanol and n-propanol contained in the heavy alcohol separation liquid can be further recycled, and the recovery rate of the material is greatly improved.

In addition, the heavy alcohol refining column 18b may separate the primary oil phase and obtain a second vapor, and it should be noted that the second vapor may include a second vapor obtained by separating the primary oil phase and the secondary oil phase in the heavy alcohol refining column 18b, and the second vapor may be an overhead vapor discharged from the top of the heavy alcohol refining column 18 b.

The heavy alcohol refining unit 18 may include a third phase separator 18e, the third phase separator 18e may be disposed downstream of the heavy alcohol refining tower 18b, the third phase separator 18e may be configured to receive the second steam discharged from the heavy alcohol refining tower 18b and perform a phase separation process on the second steam to obtain a tertiary aqueous phase and a tertiary oil phase, the third phase separator 18e may return the tertiary oil phase to the heavy alcohol refining tower 18b, and the third phase separator 18e may return the tertiary aqueous phase to the preliminary separation unit 12. The third phase splitter 18e may be provided with a third phase splitter inlet for the second steam to enter, a third oil phase outlet for the third oil phase to be discharged, and a third water phase outlet for the third water phase to be discharged, wherein the third oil phase outlet may be disposed at the top of the third phase splitter 18e, and the third water phase outlet may be disposed at the bottom of the third phase splitter 18 e. By providing the third phase separator 18e, the recovery of the heavy alcohol-separated liquid can be further improved.

The invention also provides a mixed alcohol separation method, preferably, the mixed alcohol separation system 10 provided by the invention can be used for mixed alcohol separation, and the mixed alcohol separation method comprises the following steps:

step S10: receiving an aqueous solution containing mixed alcohol and carrying out primary separation on the aqueous solution to respectively obtain methanol, a light mixed alcohol separation gas containing light alcohol with the carbon atom number of more than or equal to 2 and less than or equal to 3 and a heavy alcohol separation liquid containing heavy alcohol;

step S20: and separating the light mixed alcohol separation gas to respectively obtain each light alcohol contained in the light mixed alcohol separation gas.

In step S10, the aqueous solution containing mixed alcohol may be fischer-tropsch synthesis water, which is described in detail in the foregoing, and is not described herein again; the light mixed alcohol separation gas basically contains ethanol and n-propanol; the heavy alcohol separation liquid may contain heavy alcohol having 4 or more carbon atoms, and also contain acids such as acetic acid and propionic acid, and further contain small amounts of acetaldehyde and acetone, and a small amount of butylaldehyde, methyl acetate, ethyl acetate, 2-pentanone, n-octanol, isobutyric acid, n-heptanoic acid, and the like.

In step S10, the aqueous solution may be subjected to a dividing wall rectification to achieve a preliminary separation of the aqueous solution; preferably, the temperature of the divided wall rectification can be set to be 60-100 ℃, and preferably, the temperature of the divided wall rectification can be set to be 65-98 ℃, thereby ensuring the divided wall rectification effect. Specifically, the temperature of the bottom of the dividing wall rectifying tower 120 can be controlled to 100 ℃ to 110 ℃, and the temperature of the top of the dividing wall rectifying tower 120 can be controlled to 80 ℃ to 90 ℃.

In step S10, the reflux ratio for dividing wall distillation is set to 1 to 4, and the distillation effect can be improved by setting the reflux ratio in this range.

In step S10, the dividing wall distillation may be an atmospheric operation; in addition, the liquid phase partition rate of the dividing wall rectification may be 0.67; the vapor distribution rate for dividing wall rectification can be 0.65.

In step S10, after the fischer-tropsch synthesis water is primarily separated, the separated substances and the corresponding weight percentages of the respective substances are described in detail in the foregoing, and will not be described again here.

In step S20, the light mixed alcohol separation gas is separated to obtain ethanol and n-propanol, respectively.

In order to better recycle the alcohol substances contained in the mixed alcohol-containing aqueous solution, step S20 may include: s20 a: separating out ethanol contained in the light mixed alcohol separation gas and obtaining primary separation liquid; s20 b: the propanol contained in the primary separation liquid is separated, so that the ethanol and the propanol in the water solution containing the mixed alcohol can be respectively separated, the recovery utilization rate of the materials is improved, and the energy loss is reduced.

In step S20a, the light mixed alcohol separation gas is subjected to extractive distillation to separate ethanol contained in the light mixed alcohol separation gas, wherein the light mixed alcohol separation gas can be subjected to extractive distillation by using an extractant.

In step S20a, the extractant may include cyclohexane and/or ethylene glycol, so that the extractive distillation effect may be improved. The extractant can be recycled for extractive distillation operation again. Wherein, the ratio of the input amount of the extracting agent to the input amount of the light mixed alcohol separation gas can be the input amount of the extracting agent: the gas passing amount of the light mixed alcohol separation gas is (0.2-10): 1, the ratio of the two introduced amounts is set in the range, so that the extraction rectification effect can be improved, and the ethanol and the propanol are better separated. Preferably, the ratio of the feeding amount of the extracting agent to the feeding amount of the light mixed alcohol separation gas can be the feeding amount of the extracting agent: the introduction amount of the light mixed alcohol separation gas is (1-8): 1; further preferably, the ratio of the feeding amount of the extracting agent to the feeding amount of the light mixed alcohol separation gas can be the feeding amount of the extracting agent: the input amount of the light mixed alcohol separation gas is (1.5-5): 1.

in step S20a, the temperature of the extractive distillation can be set to 20 ℃ to 30 ℃, which not only improves the extractive distillation efficiency, but also improves the extractive distillation effect.

In step S20a, the reflux ratio of extractive distillation is set to 1 to 10, and the extractive distillation effect can be improved by setting the reflux ratio within this range. In addition, in step S20a, the extractive distillation may be an atmospheric operation.

In step S20a, the separated ethanol may be fuel ethanol.

In step S20b, the primary separated liquid is subjected to extractive distillation to separate propanol contained in the primary separated liquid, wherein the light mixed alcohol separated gas can be subjected to extractive distillation by using an extractant.

In step S20b, the extractant may include cyclohexane and/or ethylene glycol, so that the extractive distillation effect may be improved. The extractant can be recycled for extractive distillation operation again. Wherein, the ratio of the input amount of the extracting agent to the input amount of the first-stage separation liquid can be the input amount of the extracting agent: the first-stage separation liquid inlet amount is (0.2-10): 1, the ratio of the two introduced amounts is set to be in the range, so that the extraction and rectification effects can be improved, and the propanol can be better separated from the first-stage separation liquid. Preferably, the ratio of the feeding amount of the extracting agent to the feeding amount of the first-stage separation liquid can be the feeding amount of the extracting agent: the first-stage separation liquid inlet amount is (1-8): 1; further preferably, the ratio of the feeding amount of the extracting agent to the feeding amount of the first-stage separation liquid can be the feeding amount of the extracting agent: the first-stage separation liquid inlet amount is (1.5-5): 1.

it is understood that the second separation liquid is obtained after separating propanol contained in the first separation liquid. In step S20b, the secondary separated liquid may be rectified to separate the extractant and water, wherein the extractant may be recycled.

In step S20b, the temperature of the extractive distillation is set to 20 ℃ to 30 ℃, which not only improves the extractive distillation efficiency, but also improves the extractive distillation effect.

In step S20b, the reflux ratio of extractive distillation is set to 1 to 10, and the extractive distillation effect can be improved by setting the reflux ratio within this range. In addition, in step S20b, the extractive distillation may be an atmospheric operation.

In step S20b, aqueous propanol may be obtained, wherein the weight percentage of water is 3% to 10%.

The step S20 may include a step S20c of dehydrating the separated propanol to obtain anhydrous propanol. Wherein, the propanol can be rectified and dehydrated. Specifically, the temperature of the bottom of the propanol dehydrating tower 14c can be controlled to 95 ℃ to 140 ℃, and the temperature of the top of the propanol dehydrating tower 14c can be controlled to 90 ℃ to 130 ℃.

In addition, the mixed alcohol separation method may include: step S30 a: performing phase separation treatment on the heavy alcohol separation liquid separated in the step S10 to obtain a first-order oil phase and a first-order water phase; step S30 b: and rectifying the primary oil phase to obtain heavy alcohol, wherein the heavy alcohol is anhydrous heavy alcohol.

In step S30b, the temperature during rectification can be set to 100 ℃ to 105 ℃, and by setting the rectification temperature within the above range, not only the rectification efficiency is improved, but also the rectification effect is improved, and the heavy alcohol can be better separated.

In step S30b, the reflux ratio during rectification can be set to 1 to 8, and the rectification effect can be further improved by setting the reflux ratio during rectification within the above range.

When the heavy alcohol refining tower 18b is selected to rectify the first-stage oil phase, the temperature of the top of the heavy alcohol refining tower 18b can be controlled to be 90-110 ℃, and the temperature of the bottom of the heavy alcohol refining tower 18b can be controlled to be 110-130 ℃.

In addition, the mixed alcohol separation method may include: step S30 c: dehydrating the first aqueous phase to obtain a first vapor comprising heavy alcohols; step S30 d: the first steam is subjected to a phase separation treatment to obtain a secondary aqueous phase and a secondary oil phase, and the secondary oil phase is returned to the step S30b for a rectification treatment.

In step S30c, the primary aqueous phase may be dehydrated by rectification.

In step S30c, the temperature of dehydration may be set to 100 ℃ to 103 ℃, and by setting the temperature of dehydration within the above range, the efficiency of dehydration may be improved and the first steam obtained by separation may contain a large amount of heavy alcohols.

In step S30c, the dewatering reflux ratio can be set to 1 to 10, and the dewatering reflux ratio can be set within the above range, whereby the dewatering effect can be further improved.

It can be understood that the first aqueous phase may be dehydrated by the heavy alcohol dehydration column 18a, wherein the temperature of the top of the heavy alcohol dehydration column 18a may be controlled to 95 ℃ to 150 ℃ and the temperature of the bottom of the heavy alcohol dehydration column 18a may be controlled to 90 ℃ to 160 ℃.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable way. The invention is not described in detail in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.