CN114478193A - Separation method and separation device for preparing ethanol from dimethyl ether - Google Patents

Abstract

The invention discloses a separation method and a separation device for preparing ethanol from dimethyl ether, wherein the separation method comprises the following steps: the separation method has the advantages that the product components are thoroughly separated, the separation method is recycled, and meanwhile, a process combining a bulkhead rectification technology and a double-effect rectification technology is adopted, so that the separation efficiency is improved to the maximum extent, and the operation energy consumption is saved to the maximum extent.

Description

Separation method and separation device for dimethyl ether to ethanol

technical field

The invention relates to the field of product separation of dimethyl ether-to-ethanol process route products in the coal-to-ethanol technology, in particular to a separation method and a separation device for dimethyl ether to ethanol.

Background technique

Ethanol is an important bulk chemical product, widely used in medicine, food, fuel, chemical and other industries. Worldwide, the production process of ethanol includes biological fermentation, petrochemical, and coal chemical. One of the most promising uses of ethanol products is to blend with gasoline to produce ethanol gasoline. Fuel ethanol has high oxygen content, good anti-knock performance, full combustion, and reduced pollutant emissions. Vigorously developing ethanol production can effectively alleviate environmental pressures such as my country's high dependence on foreign oil and smog control.

In the production process of ethanol, the fermentation process route is widely used internationally and in China. Large-scale ethanol production enterprises mostly use the fermentation process of grain or economic crops. The United States uses corn as raw materials, Brazil uses sugarcane as raw materials, and EU countries use wheat and sugar beets as the main raw materials. The rapid expansion of fuel ethanol production capacity is bound to greatly increase the demand for the above-mentioned grains and cash crops. In recent years, global food prices have continued to rise sharply, causing widespread concern in the international community, and doubts about food security are getting louder and louder.

Affected by the "food crisis", China has stopped approving new corn fuel ethanol projects. The cellulosic fuel ethanol project fermented with cassava and corn stalks has poor economic benefits due to its high production cost and dependence on state subsidies. The petrochemical route uses ethylene as raw material to produce fuel ethanol through ethylene hydration. my country relies heavily on imports of oil, and the price of ethylene restricts the application and promotion of this method in my country.

Coal chemical route to produce ethanol is a method in which coal is used as raw material to first produce syngas and methanol, and then ethanol is produced by dimethyl ether method or acetic acid method. The production of ethanol by the acetic acid method is divided into the direct hydrogenation of acetic acid to produce ethanol and the hydrogenation of acetate to produce ethanol. Both methods require the intermediate raw material acetic acid. The economical efficiency of the ethanol product is greatly affected by the acetic acid product, and the production cost is relatively high. Ethanol is produced by the dimethyl ether method, and there is no production link of acetic acid. Methanol is synthesized by dehydration reaction to dimethyl ether, dimethyl ether and carbon monoxide. Under the action of a catalyst, the carbonylation of dimethyl ether is carried out to synthesize methyl acetate, methyl acetate and hydrogen. The hydrogenation reaction is carried out to generate crude ethanol, and the crude ethanol is obtained by separation and purification to obtain product ethanol. This process can solve the problem of overcapacity of methanol in my country. The process route mainly adopts molecular sieve catalyst or copper-based catalyst, no precious metal catalyst is required, and the production cost is relatively low; the whole reaction process only produces a trace amount of acetic acid, and the corrosion degree to the equipment is very low. Therefore, there are no special requirements for equipment materials.

In recent years, the process of preparing ethanol by dimethyl ether carbonylation and hydrogenation has been continuously developed and industrialized in my country. The ethanol industry demonstration project opened up all processes on January 11, 2017, produced qualified anhydrous ethanol, and achieved long-term stable operation.

In the carbonylation and hydrogenation of dimethyl ether to prepare ethanol, the energy consumption of the separation section of the reaction product accounts for a large proportion. According to the characteristics of this process material, it is of great significance to study an efficient and energy-saving separation process for this ethanol production process.

The clapboard rectification technology is a high-efficiency rectification technology. A vertical clapboard is set in the ordinary rectification column. The establishment of the clapboard can make a single column realize the function of two columns, and avoid the return of the concentration of intermediate components in the two-column process. Mixing, improve thermodynamic efficiency, so it can greatly reduce energy consumption. The double-effect rectification technology is a high-efficiency rectification and energy-saving process. The reboiler of the low-temperature column is heated by the condensation heat of the top material with high temperature in the device, and the energy-saving effect is obvious. Under some specific conditions, the combination of the two energy-saving technologies can achieve the best energy-saving effect.

SUMMARY OF THE INVENTION

In order to solve the problem of separation energy consumption in the prior art dimethyl ether carbonylation and hydrogenation to produce ethanol, the present invention provides a high-efficiency and energy-saving separation method and a separation device for dimethyl ether carbonylation and hydrogenation to produce ethanol.

The specific technical scheme of the present invention is as follows:

1. a separation method of dimethyl ether system ethanol, wherein, described separation method comprises the steps:

The dimethyl ether-to-ethanol reaction product is fed into a rectification and separation system to obtain a water-containing ethanol product. The rectification and separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower. The dimethyl ether-to-ethanol reaction product is obtained. Enter the degassing tower, extract the light component stream from the top of the tower, and extract the bottom stream from the bottom of the tower;

The column bottom stream enters the pre-separation tower for separation, and the methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the ethanol stream containing the remaining part of methanol is extracted from the column bottom;

The ethanol stream containing the remaining part of methanol enters the ethanol tower for separation, the water-containing ethanol product is extracted from the side line of the tower, the methanol-containing stream is extracted from the top of the tower, and the heavy component stream is extracted from the bottom of the tower;

The methanol stream containing methyl acetate and ethyl acetate extracted from the top of the pre-separation tower and the methanol containing stream extracted from the top of the ethanol tower enter the methanol recovery tower for separation, and the methyl acetate and acetic acid are extracted from the top of the tower. The stream of ethyl ester, the methanol product is taken from the bottom of the column.

2. according to the described separation method of item 1, wherein, described rectification system also comprises ethanol recovery tower, the heavy component stream extracted from ethanol tower tower bottom enters in ethanol recovery tower and separates, and recovers ethanol from tower top extraction logistics.

3. The separation method according to item 1 or 2, wherein an anhydrous ethanol product is obtained after entering the water-containing ethanol product into a molecular sieve adsorption dehydration system.

4. The separation method according to item 2 or 3, wherein the recovered ethanol stream drawn from the top of the ethanol recovery column enters the ethanol column for separation.

5. The separation method according to any one of items 1-4, wherein the dimethyl ether-to-ethanol reaction product comprises methanol, ethanol, methyl acetate, ethyl acetate, propanol, butanol and dimethyl ether.

6. The separation method according to item 5, wherein the methanol is 30-70% and the ethanol is 30-70% by mass percentage in the reaction product of dimethyl ether to ethanol.

7. The separation method according to any one of items 2-6, wherein the operating pressure of the degassing tower is 1-1000 kPa, the operating pressure of the pre-separation tower is 1-1000 kPa, and the operating pressure of the ethanol tower is 1-1000 kPa. The operating pressure is 1-1000kPa, the operating pressure of the ethanol recovery tower is 1-1000kPa, and the operating pressure of the methanol recovery tower is 1-1000kPa.

8. The separation method according to any one of items 1-7, wherein the absolute ethanol product has a purity of 90-99.999%.

9. The separation method according to any one of items 1-8, wherein the methanol product has a purity of 85-99.999%.

10. The separation method according to any one of items 1 to 9, wherein the overhead steam of the pre-separation column is used as a reboiler heat source of the ethanol column and the methanol recovery column.

11. A separation device for producing ethanol from dimethyl ether, wherein,

The separation device includes a rectification separation system, and the rectification separation system includes a degassing column, a pre-separation column, an ethanol column and a methanol recovery column;

The line of the dimethyl ether-to-ethanol reaction product stream is connected to the feed port of the degassing column for entering the dimethyl ether-to-ethanol reaction product stream into the degassing column for separation, and is extracted from the top of the degassing column. A light component stream is drawn, and a column bottom stream is drawn from the column bottom of the degassing column;

The pipeline of the column bottom stream is connected with the feed port of the pre-separation column for entering the column bottom stream into the pre-separation column for separation, and the column top of the pre-separation column is extracted containing methyl acetate and The methanol stream of ethyl acetate, the ethanol stream containing the remaining part of methanol is extracted from the bottom of the tower;

The pipeline of the ethanol stream containing the remaining part of methanol is connected with the feed port of the ethanol tower, the water-containing ethanol product is extracted from the tower side line of the ethanol tower, the methanol-containing stream is extracted from the top of the tower, and the heavy component stream is extracted from the bottom of the tower;

The line of methanol stream containing methyl acetate and ethyl acetate and the line of methanol stream are connected to the feed port of the methanol recovery column for feeding the methanol stream containing methyl acetate and ethyl acetate and the methanol stream into It is separated in the methanol recovery tower, the stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the methanol product is extracted from the bottom of the tower.

12. The separation device of clause 11, wherein,

The rectification and separation system further comprises an ethanol recovery column, and the pipeline of the heavy component stream is connected to the feed port of the ethanol recovery column for entering the heavy component stream into the ethanol recovery column for separation, and is recovered from the top of the column. Ethanol logistics.

13. Separation device according to item 11 or 12, wherein,

The separation device further comprises a molecular sieve adsorption and dehydration system, and the pipeline of the hydrous ethanol product is connected with the feed port of the molecular sieve adsorption and dehydration system for obtaining anhydrous ethanol product.

14. Separation apparatus according to item 12 or 13, wherein the line for the recovered ethanol stream is connected to the feed port of the ethanol column for feeding the recovered ethanol stream into the ethanol column for separation.

15. The separation device according to any one of items 11 to 14, wherein the ethanol column is a clapboard rectification column provided with a vertical clapboard that divides the column into Zone 1 for feed, Zone 2 for common rectification, Zone 3 for discharge, and Zone 4 for common stripping, preferably the line for the ethanol stream containing the remainder of the methanol and ethanol The first zone of the tower is connected, and the methanol-containing stream is drawn from the second zone, the aqueous ethanol product is taken from the third zone, and the heavy component stream is taken from the fourth zone. Zone 4 or Zone 1 connection.

16. The separation device according to any one of items 11 to 15, wherein the pre-separation column top is connected to the reboiler of an ethanol column and a methanol recovery column by lines, respectively, to separate the pre-separation column. The overhead steam is used as the heat source for the reboiler of the ethanol column and the methanol recovery column.

effect of invention

The invention proposes a high-efficiency and energy-saving separation process for dimethyl ether to ethanol for the first time, obtains anhydrous ethanol products, and simultaneously obtains light components such as methanol, a mixture of methyl acetate and ethyl acetate, and dimethyl ether. The product components are completely separated, and at the same time of recycling, a combination of partition rectification technology and double-effect rectification technology is adopted, which maximizes the separation efficiency and saves operating energy consumption to the greatest extent.

Description of drawings

1 is a schematic diagram of a separation device according to a specific embodiment of the present invention;

Fig. 2 is a schematic diagram of another separation device according to a specific embodiment of the present invention

Figure 3 is a schematic diagram of an ethanol column clapboard rectification column.

Among them, T1-degassing tower, T2-pre-separation tower; T3-ethanol tower; T4-methanol recovery tower; T5-ethanol recovery tower; A1- molecular sieve adsorption dehydration system; E101-T1 condenser; E102-T1 reboiler ; E202-T2 reboiler; E301-T3 condenser; E302-T3 reboiler; E401-T4 condenser; E402-T4 reboiler; E501-T5 condenser; ether-to-ethanol reaction product stream; S102-lights stream; S103-bottom stream; S201-methanol stream containing methyl acetate and ethyl acetate; S202-ethanol stream containing remaining part of methanol; S301-methanol-containing stream; S302-hydrous ethanol product; S303-heavy component stream; S401-stream containing methyl acetate and ethyl acetate; S402-methanol product; S501-recovered ethanol stream; S502-heavy impurity stream; S601-anhydrous ethanol product; S602 - Wastewater

Detailed ways

The present invention will be described in detail below with reference to the embodiments described in the accompanying drawings, wherein like numerals represent like features throughout the drawings. While specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present invention will be more thoroughly understood, and will fully convey the scope of the present invention to those skilled in the art.

It should be noted that certain terms are used in the description and claims to refer to specific components. It should be understood by those skilled in the art that the same component may be referred to by different nouns. The present specification and claims do not take the difference in terms as a way to distinguish components, but take the difference in function of the components as a criterion for distinguishing. As referred to throughout the specification and claims, "comprising" or "including" are open-ended terms and should be interpreted as "including but not limited to". Subsequent descriptions in the specification are preferred embodiments for implementing the present invention, however, the descriptions are for the purpose of general principles of the specification and are not intended to limit the scope of the present invention. The scope of protection of the present invention should be determined by the appended claims.

The invention provides a separation method for producing ethanol by hydrogenating methyl acetate, and the separation method comprises the following steps:

The dimethyl ether-to-ethanol reaction product is fed into a rectification and separation system to obtain a water-containing ethanol product. The rectification and separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower. The dimethyl ether-to-ethanol reaction product is obtained. Enter the degassing tower, extract the light component stream from the top of the tower, and extract the bottom stream from the bottom of the tower;

The column bottom stream enters the pre-separation tower for separation, and the methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the ethanol stream containing the remaining part of methanol is extracted from the column bottom;

The ethanol stream containing the remaining part of methanol enters the ethanol tower for separation, the water-containing ethanol product is extracted from the side line of the tower, the methanol-containing stream is extracted from the top of the tower, and the heavy component stream is extracted from the bottom of the tower;

The methanol stream containing methyl acetate and ethyl acetate extracted from the top of the pre-separation tower and the methanol containing stream extracted from the top of the ethanol tower enter the methanol recovery tower for separation, and the methyl acetate and acetic acid are extracted from the top of the tower. The stream of ethyl ester, the methanol product is taken from the bottom of the column.

The light end stream refers to a light end stream containing dimethyl ether and the like.

The bottoms stream refers to the stream other than the light components after the dimethyl ether to ethanol product is separated in the degassing column.

The ethanol stream containing the remainder of the methanol withdrawn from the bottom of the pre-separation column contains small amounts of methanol, ethanol and heavy alcohols.

The light end, methyl acetate and ethyl acetate containing methanol stream can be returned to the upstream reaction system to continue the reaction.

In one embodiment, the rectification system further comprises an ethanol recovery column, the heavy component stream extracted from the bottom of the ethanol column enters the ethanol recovery column for separation, the ethanol stream is recovered from the top of the column, and heavy components are extracted from the bottom of the column. Impurity logistics.

In the present invention, after the dimethyl ether-to-ethanol reaction product is separated, a purer ethanol product can be obtained, and the obtained methanol product, the stream containing methyl acetate and ethyl acetate and the heavy alcohol can be returned to the upstream reaction system for After the reaction, the product components were completely separated.

In one embodiment, the anhydrous ethanol product is obtained after entering the aqueous ethanol product into a molecular sieve adsorption dehydration system.

The molecular sieve adsorption and dehydration system is a molecular sieve adsorption and dehydration system commonly used by those skilled in the art, and those skilled in the art can select as needed. For example, the molecular sieve adsorption and dehydration system can be a liquid-phase adsorption and dehydration system, or a gas-phase adsorption and dehydration system. .

In one embodiment, the recovered ethanol stream drawn from the top of the ethanol recovery column enters the ethanol column for separation.

In one embodiment, the dimethyl ether to ethanol reaction product comprises methanol, ethanol, methyl acetate, ethyl acetate, propanol, butanol, and dimethyl ether.

In one embodiment, the methanol is 30-70% and the ethanol is 30-70% based on the total weight of the dimethyl ether-to-ethanol reaction product. Preferably, the content of methyl acetate and ethyl acetate is less than 10%. The water content is less than 5%, the content of heavy alcohol such as propanol is less than 5%, and the content of light components such as dimethyl ether is less than 5%.

For example, based on the total weight of the dimethyl ether-to-ethanol reaction product, the methanol can be 30%, 40%, 50%, 60%, 70%, etc.; the ethanol can be 30%, 40%, 50%, 60%, 70%, etc.

In one embodiment, the operating pressure of the degassing column is 1-1000kPa, and the reflux ratio is 1-50; the operating pressure of the pre-separation column is 1-1000kPa, and the reflux ratio is 1-20; the ethanol column is The operating pressure of the methanol recovery tower is 1-1000kPa, and the reflux ratio is 1-100; the operating pressure of the ethanol recovery tower is 1-1000kPa, and the reflux ratio is 1-20; the operating pressure of the methanol recovery tower is 1-1000kPa, and the reflux ratio is 1-1000kPa. 1-10.

In one embodiment, the absolute ethanol product is 90-99.999% pure.

In one embodiment, the methanol product is 85-99.999% pure.

In one embodiment, the overhead steam of the pre-separation column is used as a reboiler heat source for the ethanol column and methanol recovery column.

In the present invention, anhydrous ethanol products can be obtained by using the above-mentioned separation method, and the products are separated completely, and the top steam of the pre-separation tower is used as the reboiler heat source of the ethanol tower and the methanol recovery tower, which can reduce the operating energy to the greatest extent. consumption.

As shown in FIG. 1 , the present invention provides a separation device for producing ethanol from dimethyl ether, the separation device includes a rectification separation system (not shown in the figure), and the rectification separation system includes a degassing tower T1, Pre-separation tower T2, ethanol tower T3 and methanol recovery tower T4;

The pipeline of the dimethyl ether-to-ethanol reaction product stream S101 is connected to the feed port of the degassing column T1 for entering the dimethyl ether-to-ethanol reaction product stream S101 into the degassing column T1 for separation, and from the degassing column T1 The light component stream S102 is produced from the top of the tower of T1, and the column bottom stream S103 is produced from the bottom of the degassing tower T1. Preferably, the light component stream S102 refers to light components such as dimethyl ether. stream, the bottom stream S103 refers to the stream obtained after removing the light components, and the light components stream S102 is returned to the upstream reaction system to continue the reaction;

The pipeline of the column bottom material S103 is connected with the feed port of the pre-separation column T2 for entering the column bottom stream S103 into the pre-separation column T2 for separation, and is extracted from the top of the pre-separation column T2 Methanol stream S201 containing methyl acetate and ethyl acetate, ethanol stream S202 containing residual methanol is extracted from the bottom of the tower; preferably, the ethanol stream S202 containing residual methanol contains ethanol, heavy alcohol and a small amount of methanol;

The pipeline of the ethanol stream S202 containing the remaining part of methanol is connected with the feed port of the ethanol tower T3 to enter the ethanol stream S202 containing the remaining part of methanol into the ethanol tower T3 for separation, and water is extracted from the side line of the ethanol tower. For the ethanol product S302, the methanol-containing stream S301 is extracted from the top of the tower, and the heavy component stream S303 is extracted from the bottom of the tower; preferably, the heavy component stream S303 includes remaining water-containing ethanol and heavy alcohol;

The line of the methanol stream S201 containing methyl acetate and ethyl acetate and the line of the methanol stream S301 are connected to the feed port of the methanol recovery column T4 for mixing the methanol streams S201 and S301 containing methyl acetate and ethyl acetate with The methanol-containing stream S301 enters the methanol recovery tower T4 for separation, the stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the methanol product S402 is extracted from the bottom of the tower.

The purity of the obtained methanol product S402 is 85-99.999%.

In one embodiment, as shown in FIG. 2, the rectification and separation system further comprises an ethanol recovery column T5, and the pipeline of the heavy component stream S303 is connected to the feed port of the ethanol recovery column T5 for the heavy component stream S303 enters into the ethanol recovery tower T5 for separation, and recovers the ethanol stream S501 from the top of the tower, and takes out the heavy impurity stream S502 from the bottom of the tower.

In one embodiment, as shown in FIG. 1 and FIG. 2 , the separation device further comprises a molecular sieve adsorption and dehydration system A1, and the pipeline of the water-containing ethanol product S302 is connected with the feed port of the molecular sieve adsorption and dehydration system A1 for obtaining Anhydrous ethanol product S601 and waste water S602.

The purity of the isolated ethanol product S601 is 90-99.999%.

The present invention adopts the above-mentioned separation device, which can completely separate ethanol and other components to obtain a relatively pure ethanol product.

In one embodiment, the pipeline for recovering the ethanol stream S501 is connected to the feed port of the ethanol column T3 for entering the recovered ethanol stream S501 into the ethanol column T3 for separation for recovering ethanol.

Preferably, the pipeline for recovering the ethanol stream S501 is connected to the feed port in the middle or lower part of the ethanol tower T3 for entering the recovered ethanol stream S501 into the ethanol tower T3 for separation, for recovering ethanol.

In one embodiment, the ethanol column T3 is a clapboard rectification column, as shown in FIG. 3 , a vertical clapboard is arranged in the clapboard rectification column to divide the column into the first zone for feeding, Zone 2 for common rectification, zone 3 for discharge and zone 4 for common stripping, preferably the line of ethanol stream S202 containing the remainder of methanol and zone 1 of ethanol column T3 Connect, extract methanol-containing stream S301 from the 2nd area, extract the water-containing ethanol product S302 from the 3rd area, extract the heavy component stream S303 from the 4th area, preferably, the pipeline of reclaiming the ethanol stream S501 and the ethanol tower T3 Zone 4 or Zone 1 (not shown in Figure 2) is connected.

In one embodiment, the top of the pre-separation column T2 is connected to the reboilers E302 and E402 of the ethanol column T3 and the methanol recovery column T4 respectively through pipelines, so that the steam at the top of the pre-separation column T2 is used as the ethanol column Heat source for T3 and methanol recovery column T4 reboiler.

In one embodiment, the operating pressure of the degassing column is 1-1000kPa, and the reflux ratio is 1-50; the operating pressure of the pre-separation column is 1-1000kPa, and the reflux ratio is 1-20; the ethanol column is The operating pressure of the methanol recovery tower is 1-1000kPa, and the reflux ratio is 1-100; the operating pressure of the ethanol recovery tower is 1-1000kPa, and the reflux ratio is 1-20; the operating pressure of the methanol recovery tower is 1-1000kPa, and the reflux ratio is 1-1000kPa. 1-10.

The invention uses the top steam of the pre-separation tower to heat the reboilers of the ethanol tower and the methanol recovery tower, and the reboilers of the ethanol tower and the methanol recovery tower do not use external heat sources, thereby saving energy consumption of heat sources.

The invention adopts the technology of combining partition rectification technology and double-effect rectification technology, which not only improves the separation efficiency, but also saves the operation energy consumption to the greatest extent.

In one embodiment, a condenser E101 is provided between the top of the degassing column T1 and the light ends stream S102, and a reboiler E102 is provided at the bottom of the column.

In one embodiment, a condenser E501 is arranged between the top of the ethanol recovery column T5 and the recovered ethanol stream S501, and a reboiler E502 is arranged at the bottom of the column.

In one embodiment, a reboiler E202 is arranged at the bottom of the pre-separation column T2, a condenser E301 is arranged between the column top of the ethanol column T3 and the methanol-containing stream S301, and in the methanol recovery A condenser E401 is provided between the top of the column T4 and the stream S401 containing methyl acetate and ethyl acetate.

In one embodiment, the internals of the ethanol column T3 may be a pure packed column, a pure plate column, or a composite column of a packed column and a plate column.

Example

The present invention generally and/or specifically describes the materials and test methods used in the test. In the following examples, unless otherwise specified, % represents wt%, that is, weight percentage. The reagents or instruments used without the manufacturer's indication are conventional reagent products that can be obtained from the market.

Example 1

The device shown in Figure 1 is used for separation, and the flow rate is 72 t/h, wherein the dimethyl ether-to-ethanol reaction product stream S101 comprises methanol, ethanol, methyl acetate, ethyl acetate, water, propanol, dimethyl ether, etc., Among them, methanol is 41wt%, ethanol is 52wt%, methyl acetate and ethyl acetate are 5wt%, water is 1wt%, heavy alcohol such as propanol is 0.5wt%, and light components such as dimethyl ether are 0.5wt%.

The separation device includes a rectification separation system (not shown in the figure) and a molecular sieve adsorption and dehydration system A1, and the rectification separation system includes a degassing column T1, a pre-separation column T2, an ethanol column T3 and a methanol recovery column T4;

The pipeline of the dimethyl ether-to-ethanol reaction product stream S101 is connected to the feed port of the degassing column T1 for entering the dimethyl ether-to-ethanol reaction product stream S101 into the degassing column T1 for separation, and from the degassing column T1 The light component stream S102 is drawn from the top of the tower of T1, and the bottom stream S103 is drawn from the bottom of the degassing tower T1;

The pipeline of the column bottom material S103 is connected with the feed port of the pre-separation column T2 for entering the column bottom stream S103 into the pre-separation column T2 for separation, and is extracted from the top of the pre-separation column T2 Methanol stream S201 containing methyl acetate and ethyl acetate, and ethanol stream S202 containing remaining part of methanol is extracted from the bottom of the tower;

Described ethanol tower T3 is clapboard rectification tower (packed tower), as shown in Figure 3, described clapboard rectification tower is provided with vertical clapboard to divide the tower into the 1st zone for feeding, for Zone 2 for common rectification, zone 3 for discharge and zone 4 for common stripping, the line of ethanol stream S202 containing the remainder of methanol is connected to zone 1 of ethanol column T3, starting from 2 The methanol-containing stream S301 is extracted from the zone, the water-containing ethanol product S302 is extracted from the third zone, and the heavy component stream S303 is extracted from the fourth zone;

The line of the methanol stream S201 containing methyl acetate and ethyl acetate and the line of the methanol stream S301 are connected to the feed port of the methanol recovery column T4 for mixing the methanol streams S201 and S301 containing methyl acetate and ethyl acetate with The methanol-containing stream S301 enters the methanol recovery tower T4 for separation, and the stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the methanol product S402 is extracted from the bottom of the tower;

The pipeline of the water-containing ethanol product S302 is connected with the feed port of the molecular sieve adsorption dehydration system A1 to obtain the anhydrous ethanol product S601 and the waste water S602. The molecular sieve dehydration system includes evaporation, adsorption, desorption, and condensation equipment, using 3A molecular sieve;

The top of the pre-separation tower T2 is connected with the reboilers E302 and E402 of the ethanol tower T3 and the methanol recovery tower T4 through pipelines, so that the steam at the top of the pre-separation tower T2 is used as the ethanol tower T3 and the methanol recovery tower T4. heat source for the reboiler;

A condenser E101 is arranged between the top of the degassing column T1 and the light component stream S102, and a reboiler E102 is arranged at the bottom of the column;

A reboiler E202 is arranged at the bottom of the pre-separation column T2, a condenser E301 is arranged between the column top of the ethanol column T3 and the methanol-containing stream S301, and the column top of the methanol recovery column T4 and A condenser E401 is provided between the streams S401 containing methyl acetate and ethyl acetate.

The separation method includes the following steps:

(1) the dimethyl ether system ethanol reaction product stream S101 is entered into the degassing tower T1 and separated, the operating pressure of the degassing tower T1 is 300kPa, and the reflux ratio is 3.55, and the light components stream S102 is extracted from the top of the tower, and the Bottom extraction tower bottom stream S103, light component stream S102 includes light components such as dimethyl ether, which are returned to the upstream reaction system to continue the reaction;

(2) tower bottom stream S103 enters pre-separation tower T2 and separates, and the operating pressure of pre-separation tower T2 is 180kPa, and the reflux ratio is 2.97, and the methanol stream S201 containing methyl acetate and ethyl acetate is extracted from the top of the tower. The ethanol stream S202 containing the remaining part of methanol is extracted from the bottom of the tower;

(3) the ethanol stream S202 containing residual part methanol enters the ethanol tower T3 and separates, the operating pressure of the ethanol tower T3 is 40kPa, and the reflux ratio is 13.31, and the methanol-containing stream S301 is extracted from the 2nd district, and extracted from the 3rd district The water-containing ethanol product S302, the heavy component stream S303 is extracted from the 4th zone;

(4) the methanol stream S201 containing methyl acetate and ethyl acetate and the methanol stream S301 containing methanol enter the methanol recovery tower T4 and separate, and the operating pressure of the methanol recovery tower T4 is 50kPa, and the reflux ratio is 7.00. The stream S401 of methyl acetate and ethyl acetate, extracts methanol product S402 from the bottom of the tower, and the stream S401 containing methyl acetate and ethyl acetate returns to the upstream reaction system to continue reacting;

(5) the water-containing ethanol product S302 enters the molecular sieve adsorption and dehydration system A1 for dehydration, and obtains the absolute ethanol product S601 and the waste water S602;

After using the above-mentioned separation method and separation device for separation, the purity of the obtained methanol product is 99.9%, the ethanol content in the methanol product is 80ppm, the methanol content in the water-containing ethanol product is 400ppm, the heavy alcohol content is 200ppm, and the ethanol purity is 99.9%, and using The dehydration effect of the molecular sieve adsorption dehydration system meets the GB/T 678-2002-anhydrous ethanol standard.

Among them, the heat load, operating pressure and reflux ratio of each column are shown in Table 1.

Table 1 Heat load, operating pressure and reflux ratio of each column

tower name degassing tower Pre-separation tower Ethanol tower Methanol recovery tower Tower heat load MKCAL/HR 2.86 28.30 19.46 8.86 External heating load 2.86 28.30 0 0 Reflux ratio 3.55 2.97 13.31 7.00 tower operating pressure KPA 300 180 40 50

As can be seen from Table 1, the total heat load for external use is 31.16MKCAL/HR.

Example 2

The device shown in FIG. 2 is used for separation, and the flow rate is the same as that in Example 1, wherein the dimethyl ether-to-ethanol reaction product stream S101 comprises methanol, ethanol, methyl acetate, ethyl acetate, water, propanol, dimethyl ether, etc. , among which, methanol is 51wt%, ethanol is 42wt%, methyl acetate and ethyl acetate are 5wt%, water is 1wt%, alcohols such as propanol are 0.5wt%, and light components such as dimethyl ether are 0.5wt% .

The separation device includes a rectification separation system (not shown in the figure) and a molecular sieve adsorption dehydration system A1. The rectification separation system includes a degassing column T1, a pre-separation column T2, an ethanol column T3, a methanol recovery column T4 and ethanol. Recovery tower T5;

The pipeline of the dimethyl ether-to-ethanol reaction product stream S101 is connected to the feed port of the degassing column T1 for entering the dimethyl ether-to-ethanol reaction product stream S101 into the degassing column T1 for separation, and from the degassing column T1 The light component stream S102 is drawn from the top of the tower of T1, and the bottom stream S103 is drawn from the bottom of the degassing tower T1;

The pipeline of the column bottom stream S103 is connected with the feed port of the pre-separation tower T2 for entering the column bottom stream S103 into the pre-separation column T2 for separation, and is extracted from the top of the pre-separation column T2 Methanol stream S201 containing methyl acetate and ethyl acetate, and ethanol stream S202 containing remaining part of methanol is extracted from the bottom of the tower;

Described ethanol tower T3 is clapboard rectification tower (packed tower), as shown in Figure 3, described clapboard rectification tower is provided with vertical clapboard to divide the tower into the 1st zone for feeding, for Zone 2 for common rectification, zone 3 for discharge and zone 4 for common stripping, the line of ethanol stream S202 containing the remainder of methanol is connected to zone 1 of ethanol column T3, starting from 2 The methanol-containing stream S301 is extracted from the zone, the water-containing ethanol product S302 is extracted from the third zone, and the heavy component stream S303 is extracted from the fourth zone;

The line of the methanol stream S201 containing methyl acetate and ethyl acetate and the line of the methanol stream S301 are connected to the feed port of the methanol recovery column T4 for mixing the methanol streams S201 and S301 containing methyl acetate and ethyl acetate with The methanol-containing stream S301 enters the methanol recovery tower T4 for separation, and the stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the methanol product S402 is extracted from the bottom of the tower;

The pipeline of the water-containing ethanol product S302 is connected with the feed port of the molecular sieve adsorption dehydration system A1 to obtain the anhydrous ethanol product S601 and the waste water S602. The molecular sieve dehydration system includes evaporation, adsorption, desorption, and condensation equipment, using 3A molecular sieve;

The pipeline of the heavy component stream S303 is connected with the feed port of the ethanol recovery tower T5 to separate the heavy component stream S303 into the ethanol recovery tower T5, and the ethanol stream S501 is recovered from the top of the tower, and the heavy component is recovered from the bottom of the tower. Impurity logistics S502;

The pipeline that reclaims ethanol stream S501 is connected with the feed port in the middle and lower part of the ethanol tower T3 to be used for entering the reclaimed ethanol stream S501 into the ethanol tower T3 for separation, for reclaiming ethanol;

The top of the pre-separation tower T2 is connected with the reboilers E302 and E402 of the ethanol tower T3 and the methanol recovery tower T4 through pipelines, so that the steam at the top of the pre-separation tower T2 is used as the ethanol tower T3 and the methanol recovery tower T4. heat source for the reboiler;

A condenser E101 is arranged between the top of the degassing column T1 and the light component stream S102, and a reboiler E102 is arranged at the bottom of the column;

A reboiler E202 is arranged at the bottom of the pre-separation column T2, a condenser E301 is arranged between the column top of the ethanol column T3 and the methanol-containing stream S301, and the column top of the methanol recovery column T4 and Condenser E401 is provided between the stream S401 containing methyl acetate and ethyl acetate;

A condenser E501 is arranged between the top of the ethanol recovery column T5 and the recovered ethanol stream S501, and a reboiler E502 is arranged at the bottom of the column.

The separation method includes the following steps:

(1) the dimethyl ether system ethanol reaction product stream S101 is entered into the degassing tower T1 and separated, the operating pressure of the degassing tower T1 is 300kPa, and the reflux ratio is 3.55, and the light components stream S102 is extracted from the top of the tower, and the Bottom extraction tower bottom stream S103, light component stream S102 includes light components such as dimethyl ether, which are returned to the upstream reaction system to continue the reaction;

(2) tower bottom stream S103 enters in pre-separation tower T2 and separates, and the operating pressure of pre-separation tower T2 is 160kPa, and the reflux ratio is 2.73, and the methanol stream S201 containing methyl acetate and ethyl acetate is extracted from the top of the tower, from The ethanol stream S202 containing the remaining part of methanol is extracted from the bottom of the tower;

(3) the ethanol stream S202 containing residual part methanol enters the ethanol tower T3 and separates, the operating pressure of the ethanol tower T3 is 110kPa, and the reflux ratio is 10.61, and the methanol-containing stream S301 is extracted from the 2nd district, and extracted from the 3rd district The water-containing ethanol product S302, the heavy component stream S303 is extracted from the 4th zone;

(4) the methanol stream S201 containing methyl acetate and ethyl acetate and the methanol stream S301 containing methanol enter the methanol recovery tower T4 and separate, and the operating pressure of the methanol recovery tower T4 is 110kPa, and the reflux ratio is 7.00. The stream S401 of methyl acetate and ethyl acetate, extracts methanol product S402 from the bottom of the tower, and the stream S401 containing methyl acetate and ethyl acetate returns to the upstream reaction system to continue reacting;

(5) the water-containing ethanol product S302 enters the molecular sieve adsorption and dehydration system A1 for dehydration, and obtains the absolute ethanol product S601 and the waste water S602;

(6) heavy component stream S303 enters into ethanol recovery tower T5 and separates, and the operating pressure of ethanol recovery tower T5 is 200kPa, and the reflux ratio is 2.00, and recovery ethanol stream S501 is drawn from the top of the tower, and heavy impurity stream S502 is drawn from the bottom of the tower ; Recover ethanol stream S501 and enter into ethanol tower T3 to continue separation.

After using the above-mentioned separation method and separation device for separation, the purity of the obtained methanol product is 99.9%, the ethanol content in the methanol product is 80ppm, the methanol content in the water-containing ethanol product is 400ppm, the heavy alcohol content is 200ppm, and the ethanol purity is 99.9%, and using The dehydration effect of the molecular sieve adsorption dehydration system meets the GB/T 678-2002-anhydrous ethanol standard.

Among them, the heat load, operating pressure and reflux ratio of each column are shown in Table 2.

Table 2 Heat load, operating pressure and reflux ratio of each column

tower name degassing tower Pre-separation tower Ethanol tower Ethanol recovery tower Methanol recovery tower Tower heat load MKCAL/HR 2.78 32.37 20.16 0.59 12.69 External heating load 2.78 32.37 0 0.59 0 Reflux ratio 3.55 2.73 10.61 2.00 7.00 tower operating pressure KPA 300 260 110 200 110

As can be seen from Table 2, the total heat load for external use is 35.74MKCAL/HR

To sum up, by adopting the separation method of the present invention for separation, the obtained ethanol product and methanol product have relatively high purity and good separation effect, and the combination of the partition wall fractionation technology and the double-effect distillation technology is adopted, and the maximum Reduce operating energy consumption to a certain extent and achieve the purpose of energy saving.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications to equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still belong to the protection scope of the technical solutions of the present invention.

Claims (16)

1. a separation method of dimethyl ether system ethanol, is characterized in that, described separation method comprises the steps: The dimethyl ether-to-ethanol reaction product is fed into a rectification and separation system to obtain a water-containing ethanol product. The rectification and separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower. The dimethyl ether-to-ethanol reaction product is obtained. Enter the degassing tower, extract the light component stream from the top of the tower, and extract the bottom stream from the bottom of the tower; The column bottom stream enters the pre-separation tower for separation, and the methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the ethanol stream containing the remaining part of methanol is extracted from the column bottom; The ethanol stream containing the remaining part of methanol enters the ethanol tower for separation, the water-containing ethanol product is extracted from the side line of the tower, the methanol-containing stream is extracted from the top of the tower, and the heavy component stream is extracted from the bottom of the tower; The methanol stream containing methyl acetate and ethyl acetate extracted from the top of the pre-separation tower and the methanol containing stream extracted from the top of the ethanol tower enter the methanol recovery tower for separation, and the methyl acetate and acetic acid are extracted from the top of the tower. The stream of ethyl ester, the methanol product is taken from the bottom of the column. 2. separation method according to claim 1, is characterized in that, described rectification system also comprises ethanol recovery tower, and the heavy component stream extracted from ethanol tower tower bottom enters in ethanol recovery tower and separates, from tower top out the recovered ethanol stream. 3. The separation method according to claim 1 or 2, wherein the dehydrated ethanol product is obtained after entering the water-containing ethanol product into the molecular sieve adsorption dehydration system. 4. separation method according to claim 2 or 3 is characterized in that, the recovery ethanol stream drawn from the tower top of ethanol recovery tower enters into ethanol tower and separates. 5. separation method according to any one of claim 1-4, is characterized in that, described dimethyl ether ethanol reaction product comprises methanol, ethanol, methyl acetate, ethyl acetate, propanol, butanol and diethyl alcohol methyl ether. 6 . The separation method according to claim 5 , wherein the methanol is 30-70% and the ethanol is 30-70% in terms of the mass percentage in the dimethyl ether-to-ethanol reaction product. 7 . . 7. The separation method according to any one of claims 2-6, wherein the operating pressure of the degassing tower is 1-1000kPa, the operating pressure of the pre-separation tower is 1-1000kPa, and the The operating pressure of the ethanol tower is 1-1000kPa, the operating pressure of the ethanol recovery tower is 1-1000kPa, and the operating pressure of the methanol recovery tower is 1-1000kPa. 8. The separation method according to any one of claims 1-7, wherein the purity of the absolute ethanol product is 90-99.999%. 9. The separation method according to any one of claims 1-8, wherein the methanol product has a purity of 85-99.999%. 10. The separation method according to any one of claims 1-9, wherein the overhead steam of the pre-separation tower is used as the reboiler heat source of the ethanol tower and the methanol recovery tower. 11. A separation device for producing ethanol from dimethyl ether, characterized in that, The separation device includes a rectification separation system, and the rectification separation system includes a degassing column, a pre-separation column, an ethanol column and a methanol recovery column; The line of the dimethyl ether-to-ethanol reaction product stream is connected to the feed port of the degassing column for entering the dimethyl ether-to-ethanol reaction product stream into the degassing column for separation, and is extracted from the top of the degassing column. A light component stream is drawn, and a tower bottom stream is drawn from the bottom of the degassing tower; The pipeline of the column bottom stream is connected with the feed port of the pre-separation column for entering the column bottom stream into the pre-separation column for separation, and the column top of the pre-separation column is extracted containing methyl acetate and The methanol stream of ethyl acetate, the ethanol stream containing the remaining part of methanol is extracted from the bottom of the tower; The pipeline of the ethanol stream containing the remaining part of methanol is connected with the feed port of the ethanol tower, the water-containing ethanol product is extracted from the tower side line of the ethanol tower, the methanol-containing stream is extracted from the top of the tower, and the heavy component stream is extracted from the bottom of the tower; The line of methanol stream containing methyl acetate and ethyl acetate and the line of methanol stream are connected to the feed port of the methanol recovery column for feeding the methanol stream containing methyl acetate and ethyl acetate and the methanol stream into It is separated in the methanol recovery tower, the stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and the methanol product is extracted from the bottom of the tower. 12. The separation device of claim 11, wherein The rectification and separation system further comprises an ethanol recovery column, and the pipeline of the heavy component stream is connected to the feed port of the ethanol recovery column for entering the heavy component stream into the ethanol recovery column for separation, and is recovered from the top of the column. Ethanol logistics. 13. The separation device according to claim 11 or 12, characterized in that, The separation device further comprises a molecular sieve adsorption and dehydration system, and the pipeline of the hydrous ethanol product is connected with the feed port of the molecular sieve adsorption and dehydration system for obtaining anhydrous ethanol product. 14. The separation device according to claim 12 or 13, wherein the pipeline for recovering the ethanol stream is connected to the feed port of the ethanol column for feeding the recovered ethanol stream into the ethanol column for separation. 15. The separation device according to any one of claims 11-14, wherein the ethanol column is a clapboard rectification column, and a vertical clapboard is arranged in the clapboard rectification column, and the column is Divided into zone 1 for feed, zone 2 for common rectification, zone 3 for output, and zone 4 for common stripping, preferably, of the ethanol stream containing the remainder of the methanol The pipeline is connected to the first zone of the ethanol column, and the methanol-containing stream is drawn from the second zone, the aqueous ethanol product is taken from the third zone, and the heavy component stream is taken from the fourth zone. The Tower's Zone 4 or Zone 1 connection. 16. The separation device according to any one of claims 11-15, wherein the top of the pre-separation column is connected to the reboiler of an ethanol column and a methanol recovery column through pipelines, respectively, to separate the pre-separation column. The steam at the top of the separation tower is used as the heat source for the reboiler of the ethanol tower and the methanol recovery tower.

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