CN114478193B - Separation method and separation device for preparing ethanol from dimethyl ether - Google Patents
Separation method and separation device for preparing ethanol from dimethyl ether Download PDFInfo
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 808
- 238000000926 separation method Methods 0.000 title claims abstract description 163
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 claims abstract description 25
- 238000005192 partition Methods 0.000 claims abstract description 5
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 494
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 153
- 239000000047 product Substances 0.000 claims description 79
- 238000011084 recovery Methods 0.000 claims description 74
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 claims description 55
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 claims description 55
- 238000006297 dehydration reaction Methods 0.000 claims description 29
- 238000010992 reflux Methods 0.000 claims description 29
- 239000007795 chemical reaction product Substances 0.000 claims description 28
- 230000018044 dehydration Effects 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 25
- 238000001179 sorption measurement Methods 0.000 claims description 24
- 239000002808 molecular sieve Substances 0.000 claims description 23
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 23
- 238000007872 degassing Methods 0.000 claims description 10
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 6
- 238000005516 engineering process Methods 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 11
- 238000005265 energy consumption Methods 0.000 abstract description 9
- 230000008901 benefit Effects 0.000 abstract description 2
- 235000019441 ethanol Nutrition 0.000 description 251
- 235000019439 ethyl acetate Nutrition 0.000 description 46
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 21
- 238000006243 chemical reaction Methods 0.000 description 15
- 238000004519 manufacturing process Methods 0.000 description 12
- 238000005984 hydrogenation reaction Methods 0.000 description 7
- 238000011144 upstream manufacturing Methods 0.000 description 7
- 238000005810 carbonylation reaction Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000000446 fuel Substances 0.000 description 6
- 239000002351 wastewater Substances 0.000 description 6
- 150000001298 alcohols Chemical class 0.000 description 5
- 230000006315 carbonylation Effects 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 4
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 240000008042 Zea mays Species 0.000 description 3
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 3
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 3
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- 238000009833 condensation Methods 0.000 description 3
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- 239000004302 potassium sorbate Substances 0.000 description 3
- 239000002151 riboflavin Substances 0.000 description 3
- 239000000661 sodium alginate Substances 0.000 description 3
- PPASLZSBLFJQEF-RKJRWTFHSA-M sodium ascorbate Substances [Na+].OC[C@@H](O)[C@H]1OC(=O)C(O)=C1[O-] PPASLZSBLFJQEF-RKJRWTFHSA-M 0.000 description 3
- 239000004149 tartrazine Substances 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 125000000118 dimethyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
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- 230000008020 evaporation Effects 0.000 description 2
- 235000013305 food Nutrition 0.000 description 2
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- 239000003502 gasoline Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- -1 propanol Chemical compound 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 241000219310 Beta vulgaris subsp. vulgaris Species 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 240000003183 Manihot esculenta Species 0.000 description 1
- 235000016735 Manihot esculenta subsp esculenta Nutrition 0.000 description 1
- 240000000111 Saccharum officinarum Species 0.000 description 1
- 235000007201 Saccharum officinarum Nutrition 0.000 description 1
- 235000021536 Sugar beet Nutrition 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
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- 239000003344 environmental pollutant Substances 0.000 description 1
- NZDGNIJHHWDSIW-UHFFFAOYSA-N ethyl acetate;methyl acetate Chemical compound COC(C)=O.CCOC(C)=O NZDGNIJHHWDSIW-UHFFFAOYSA-N 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
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- 229910000510 noble metal Inorganic materials 0.000 description 1
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- 231100000719 pollutant Toxicity 0.000 description 1
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- 239000010902 straw Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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 provided by the invention has the advantages that the separation of product components is thorough, the separation is recycled, and meanwhile, the separation efficiency is improved to the greatest extent and the operation energy consumption is saved to the greatest extent by adopting a process combining a partition wall rectification technology and a double-effect rectification technology.
Description
Technical Field
The invention relates to the field of separation of products in a process route of preparing ethanol from dimethyl ether in a coal-to-ethanol technology, in particular to a separation method and a separation device for preparing ethanol from dimethyl ether.
Background
Ethanol is an important large-scale chemical product and is widely used in the industries of medicine, food, fuel, chemical industry and the like. Worldwide, the production process of ethanol comprises a biological fermentation method, a petrochemical method and a coal chemical method. One of the most promising uses of the ethanol product is to mix with gasoline to produce ethanol gasoline, the fuel ethanol has high oxygen content and good antiknock performance, and the ethanol product is fully combusted to reduce pollutant emission. The ethanol production is greatly developed, and the environmental protection pressures of too high external dependence of petroleum, haze treatment and the like in China can be effectively relieved.
In the ethanol production process, fermentation process routes are widely applied internationally and in China, and large-scale ethanol production enterprises mostly adopt grain or cash crop fermentation processes. The united states uses corn as the raw material and the brazil uses sugar cane as the raw material, while the european union nations use wheat and sugar beet as the main raw materials. The rapid expansion of fuel ethanol production has meant a great increase in demand for such food and commercial crops. In recent years, the continuous and large increase of global grain prices brings about the general attention of the international society, and the challenge of grain safety is higher and higher.
Influenced by the grain crisis, new corn fuel ethanol projects are stopped being approved at home nowadays. The cellulose fuel ethanol project fermented by cassava and corn straws has poor economic benefit due to the high production cost, dependence on national subsidies and other factors. The petrochemical process uses ethylene as raw material and prepares fuel ethanol through ethylene hydration. Petroleum in China depends on import in a large amount, and the price of ethylene restricts the application and popularization of the method in China.
The process of preparing alcohol by coal chemical route is to prepare synthetic gas and methanol first and then to prepare alcohol by dimethyl ether or acetic acid. The method for preparing the ethanol by the acetic acid method is divided into the method for preparing the ethanol by directly hydrogenating the acetic acid and the method for preparing the ethanol by hydrogenating the acetic ester, the two methods both require intermediate raw materials of acetic acid, the economy of the ethanol product is greatly influenced by the acetic acid product, and the production cost is relatively high. The dimethyl ether method is used for preparing the ethanol, the production link of acetic acid does not exist, the methanol is used for synthesizing the dimethyl ether through the dehydration reaction, the dimethyl ether and the carbon monoxide are used for synthesizing the methyl acetate through the dimethyl ether carbonylation reaction under the action of the catalyst, the methyl acetate and the hydrogen are used for hydrogenation reaction to generate the crude ethanol, and the crude ethanol is separated and refined to obtain the product ethanol. The process can solve the problem of excessive methanol productivity in China, and the process route mainly adopts a molecular sieve catalyst or a copper-based catalyst, does not need a noble metal catalyst, and has relatively low production cost; only a trace amount of acetic acid is generated in the whole reaction process, and the corrosion degree of equipment is very low, so that no special requirement is made on the material of the equipment.
In recent years, the process for preparing ethanol by carbonylation hydrogenation of dimethyl ether is continuously developed and industrially developed in China, and the industrial demonstration project of preparing ethanol by carbonylation hydrogenation of dimethyl ether with annual yield of 10 ten thousand tons/year, which is commonly developed by large-scale connectives and prolonged petroleum groups, is opened up in the whole flow in 2017, 1 month and 11 days, so that qualified absolute ethanol is produced, and long-time stable operation is realized.
In the process for preparing the ethanol by the carbonylation hydrogenation of the dimethyl ether, the energy consumption of a separation section of a reaction product is relatively large, and the separation process with high efficiency and energy conservation is researched aiming at the characteristics of materials of the process, so that the method has great significance on the ethanol production process.
The baffle plate rectifying technology belongs to the efficient rectifying technology, a vertical baffle plate is arranged in a common rectifying tower, and the arrangement of the baffle plate can enable a single tower to realize the functions of two towers, avoid back mixing of the concentration of intermediate components in the flow of the two towers, improve the thermodynamic efficiency, and greatly reduce the energy consumption. The double-effect rectification technology belongs to a high-efficiency rectification energy-saving process, and has obvious energy-saving effect by using high-temperature tower top material condensation heat in a device to heat a reboiler of a low-temperature tower. Under specific conditions, the two energy-saving technologies are combined, so that the optimal energy-saving effect can be achieved.
Disclosure of Invention
In order to solve the problem of separation energy consumption in the process of preparing ethanol by dimethyl ether carbonylation hydrogenation in the prior art, the invention provides a separation method and a separation device for preparing ethanol by dimethyl ether carbonylation hydrogenation, which are efficient and energy-saving.
The specific technical scheme of the invention is as follows:
1. A separation method for preparing ethanol from dimethyl ether, wherein the separation method comprises the following steps:
The method comprises the steps that a reaction product of preparing ethanol from dimethyl ether enters a rectification separation system to obtain an aqueous ethanol product, wherein the rectification separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower, the reaction product of preparing ethanol from dimethyl ether enters the degassing tower, a light component material flow is extracted from the top of the tower, and a bottom material flow is extracted from the bottom of the tower;
The bottom stream enters a pre-separation tower to be separated, a methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and an ethanol stream containing the rest part of methanol is extracted from the bottom of the tower;
the ethanol stream containing the rest part of methanol enters an ethanol tower for separation, an aqueous ethanol product is extracted from the side line of the tower, a methanol-containing stream is extracted from the top of the tower, and a 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 stream containing methyl acetate and ethyl acetate extracted from the top of the ethanol tower enter a methanol recovery tower to be separated, the stream containing methyl acetate and ethyl acetate is extracted from the top of the ethanol tower, and the methanol product is extracted from the bottom of the ethanol tower.
2. The separation method according to item 1, wherein the rectification system further comprises an ethanol recovery column, the heavy component stream withdrawn from the bottom of the ethanol column is fed into the ethanol recovery column to be separated, and the recovered ethanol stream is withdrawn from the top of the ethanol column.
3. The separation method according to item 1 or 2, wherein the aqueous ethanol product is subjected to a molecular sieve adsorption dehydration system to obtain an absolute ethanol product.
4. The separation method according to item 2 or 3, wherein the recovered ethanol stream withdrawn from the top of the ethanol recovery column is fed to the ethanol column for separation.
5. The separation method according to any one of claims 1 to 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 to 70% and the ethanol is 30 to 70% by mass percentage based on the reaction product of dimethyl ether to ethanol.
7. The separation method according to any one of claims 2 to 6, wherein an operation pressure of the degassing column is 1 to 1000kPa, an operation pressure of the pre-separation column is 1 to 1000kPa, an operation pressure of the ethanol recovery column is 1 to 1000kPa, and an operation pressure of the methanol recovery column is 1 to 1000kPa.
8. The separation method according to any one of claims 1 to 7, wherein the absolute ethanol product has a purity of 90-99.999%.
9. The separation process of 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 to 9, wherein the overhead vapor of the pre-separation column is used as a reboiler heat source for the ethanol column and the methanol recovery column.
11. A separation device for preparing ethanol from dimethyl ether, wherein,
The separation device comprises a rectification separation system, wherein the rectification separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower;
A pipeline of the reaction product stream of the dimethyl ether to the ethanol is connected with a feed inlet of a degasser for separating the reaction product stream of the dimethyl ether to the ethanol, a light component stream is extracted from the top of the degasser, and a bottom stream is extracted from the bottom of the degasser;
The pipeline of the bottom stream is connected with the feed inlet of the pre-separation tower, so that the bottom stream enters the pre-separation tower for separation, a methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the pre-separation tower, and an ethanol stream containing the rest part of methanol is extracted from the bottom of the pre-separation tower;
a pipeline of an ethanol stream containing the rest part of methanol is connected with a feed inlet of the ethanol tower, an aqueous ethanol product is extracted from a tower side line of the ethanol tower, a methanol stream is extracted from the tower top, and a heavy component stream is extracted from the tower bottom;
And a pipeline of a methanol stream containing methyl acetate and ethyl acetate and a pipeline of a methanol stream containing methanol are connected with a feed inlet of the methanol recovery tower so as to be used for separating the methanol stream containing methyl acetate and ethyl acetate and the methanol stream containing methanol into the methanol recovery tower, the stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and a methanol product is extracted from the bottom of the tower.
12. The separation device according to item 11, wherein,
The rectification separation system further comprises an ethanol recovery tower, a pipeline of the heavy component stream is connected with a feed inlet of the ethanol recovery tower and used for separating the heavy component stream into the ethanol recovery tower, and the ethanol stream is recovered from the top of the tower.
13. The separation device according to item 11 or 12, wherein,
The separation device also comprises a molecular sieve adsorption dehydration system, and a pipeline of the hydrous ethanol product is connected with a feed inlet of the molecular sieve adsorption dehydration system so as to obtain an anhydrous ethanol product.
14. The separation device of claim 12 or 13, wherein the line for recovering the ethanol stream is connected to a feed inlet of an ethanol column for separating the recovered ethanol stream into the ethanol column.
15. The separation device according to any one of claims 11-14, wherein the ethanol column is a baffle rectification column, wherein a vertical baffle is provided in the baffle rectification column, dividing the column into a 1 st zone for feeding, a2 nd zone for public rectification, a 3 rd zone for discharging and a 4 th zone for public stripping, preferably a line for the ethanol stream containing the remaining part of the methanol is connected to the 1 st zone of the ethanol column, a methanol-containing stream is withdrawn from the 2 nd zone, an aqueous ethanol product is withdrawn from the 3 rd zone, a heavy component stream is withdrawn from the 4 th zone, preferably a line for recovering the ethanol stream is connected to the 4 th zone or the 1 st zone of the ethanol column.
16. The separation device according to any one of claims 11 to 15, wherein the top of the pre-separation column is connected to reboilers of the ethanol column and the methanol recovery column, respectively, through pipelines to use steam at the top of the pre-separation column as heat sources for reboilers of the ethanol column and the methanol recovery column.
ADVANTAGEOUS EFFECTS OF INVENTION
The invention provides an efficient and energy-saving separation process for preparing ethanol from dimethyl ether for the first time, and an absolute ethanol product is obtained, and light components such as recycled methanol, methyl acetate, ethyl acetate mixture, dimethyl ether and the like are obtained. The product components are thoroughly separated and recycled, and meanwhile, the separation efficiency is improved to the greatest extent and the operation energy consumption is saved to the greatest extent by adopting a process combining a partition wall rectification technology and a double-effect rectification technology.
Drawings
FIG. 1 is a schematic view of a separation device according to an embodiment of the present invention;
FIG. 2 is a schematic view of another separation device according to an embodiment of the present invention
FIG. 3 is a schematic diagram of an ethanol column baffle rectification column.
Wherein, the T1-degasser, T2-pre-separator; a T3-ethanol column; a T4-methanol recovery column; a T5-ethanol recovery column; a1-a molecular sieve adsorption dehydration system; an E101-T1 condenser; E102-T1 reboiler; E202-T2 reboiler; E301-T3 condenser; E302-T3 reboiler; E401-T4 condenser; E402-T4 reboiler; E501-T5 condenser; e502-reboiler; s101-dimethyl ether to prepare an ethanol reaction product stream; s102-a light component stream; s103-a bottom stream; s201, a methanol stream containing methyl acetate and ethyl acetate; s202, an ethanol stream containing the rest part of methanol; s301-a methanol-containing stream; s302, an aqueous ethanol product; s303-a heavy component stream; s401, a stream containing methyl acetate and ethyl acetate; s402-methanol product; s501, recovering an ethanol stream; s502-a heavy impurity stream; s601-absolute ethanol product; s602-wastewater
Detailed Description
The present invention will now be described in detail with reference to the embodiments thereof as illustrated in the accompanying drawings, wherein like numerals refer to like features throughout. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It should be noted that certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will understand that a person may refer to the same component by different names. The specification and claims do not identify differences in terms of components, but rather differences in terms of the functionality of the components. As referred to throughout the specification and claims, the terms "include" or "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description hereinafter sets forth a preferred embodiment for practicing the invention, but is not intended to limit the scope of the invention, as the description proceeds with reference to the general principles of the description. The scope of the invention is defined by the appended claims.
The invention provides a separation method for preparing ethanol by methyl acetate hydrogenation, which comprises the following steps:
The method comprises the steps that a reaction product of preparing ethanol from dimethyl ether enters a rectification separation system to obtain an aqueous ethanol product, wherein the rectification separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower, the reaction product of preparing ethanol from dimethyl ether enters the degassing tower, a light component material flow is extracted from the top of the tower, and a bottom material flow is extracted from the bottom of the tower;
The bottom stream enters a pre-separation tower to be separated, a methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and an ethanol stream containing the rest part of methanol is extracted from the bottom of the tower;
the ethanol stream containing the rest part of methanol enters an ethanol tower for separation, an aqueous ethanol product is extracted from the side line of the tower, a methanol-containing stream is extracted from the top of the tower, and a 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 stream containing methyl acetate and ethyl acetate extracted from the top of the ethanol tower enter a methanol recovery tower to be separated, the stream containing methyl acetate and ethyl acetate is extracted from the top of the ethanol tower, and the methanol product is extracted from the bottom of the ethanol tower.
The light component stream refers to a light component stream containing dimethyl ether or the like.
The bottom stream refers to a stream of the dimethyl ether to ethanol product after separation in the degasser, except for light components.
The ethanol stream containing the remaining portion of the methanol withdrawn from the bottom of the pre-separation column contains small amounts of methanol, ethanol and heavy alcohols.
The light components, methyl acetate and ethyl acetate containing methanol stream may be returned to the upstream reaction system for further reaction.
In one embodiment, the rectification system further comprises an ethanol recovery tower, the heavy component stream extracted from the bottom of the ethanol tower enters the ethanol recovery tower for separation, the recovered ethanol stream is extracted from the top of the tower, and the heavy impurity stream is adopted from the bottom of the tower.
According to the invention, after the reaction product of preparing ethanol from dimethyl ether is separated, a purer ethanol product can be obtained, and the obtained methanol product, a material flow containing methyl acetate and ethyl acetate and heavy alcohol can be returned to an upstream reaction system for reaction, so that the components of the product are thoroughly separated.
In one embodiment, the aqueous ethanol product is passed to a molecular sieve adsorption dehydration system to produce an absolute ethanol product.
The molecular sieve adsorption and dehydration system is a molecular sieve adsorption and dehydration system commonly used by a person skilled in the art, and the person skilled in the art can select the molecular sieve adsorption and dehydration system according to the needs, 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 withdrawn from the top of the ethanol recovery column is passed to an 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 alcohols such as propanol is less than 5%, and the content of light components such as dimethyl ether is less than 5%.
For example, the methanol may be 30%, 40%, 50%, 60%, 70%, etc., based on the total weight of the dimethyl ether to ethanol reaction product; the ethanol may be 30%, 40%, 50%, 60%, 70%, etc.
In one embodiment, the operating pressure of the degasser is from 1 to 1000kPa and the reflux ratio is from 1 to 50; the operation pressure of the pre-separation tower is 1-1000kPa, and the reflux ratio is 1-20; the operating pressure of the ethanol 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 1-10.
In one embodiment, the absolute ethanol product has a purity of 90 to 99.999%.
In one embodiment, the methanol product has a purity of 85 to 99.999%.
In one embodiment, the overhead vapor of the pre-separation column is used as the reboiler heat source for the ethanol column and the methanol recovery column.
The separation method can be used for obtaining the absolute ethyl alcohol product, the product is thoroughly separated, and the tower top steam of the pre-separation tower is used as a heat source of reboilers of the ethyl alcohol tower and the methyl alcohol recovery tower, so that the operation energy consumption can be reduced to the greatest extent.
As shown in fig. 1, the present invention provides a separation device for preparing ethanol from dimethyl ether, which comprises a rectification separation system (not shown in the figure), wherein the rectification separation system comprises a degasser tower T1, a pre-separation tower T2, an ethanol tower T3 and a methanol recovery tower T4;
A pipeline of the reaction product stream S101 for preparing the ethanol by the dimethyl ether is connected with a feed inlet of a degasser T1 for separating the reaction product stream S101 for preparing the ethanol by the dimethyl ether into the degasser T1, a light component stream S102 is extracted from the top of the degasser T1, a bottom stream S103 is extracted from the bottom of the degasser T1, preferably, the light component stream S102 refers to a light component stream such as the dimethyl ether, the bottom stream S103 refers to a stream obtained after removing the light component, and the light component stream S102 returns to an upstream reaction system for continuous reaction;
The pipeline of the tower bottom material S103 is connected with the feed inlet of the pre-separation tower T2, so that the tower bottom material S103 enters the pre-separation tower T2 for separation, a methanol material S201 containing methyl acetate and ethyl acetate is extracted from the tower top of the pre-separation tower T2, and an ethanol material S202 containing the rest part of methanol is extracted from the tower bottom; preferably, the ethanol stream S202 comprising the remaining portion of methanol comprises ethanol, heavy alcohols and small amounts of methanol;
A pipeline of an ethanol stream S202 containing the residual part of methanol is connected with a feed inlet of the ethanol tower T3 so as to separate the ethanol stream S202 containing the residual part of methanol into the ethanol tower T3, an aqueous ethanol product S302 is extracted from a tower side line of the ethanol tower, a methanol-containing stream S301 is extracted from the top of the tower, and a heavy component stream S303 is extracted from the bottom of the tower; preferably, the heavy component stream S303 comprises residual aqueous ethanol and heavy alcohols;
A line for the methanol stream S201 containing methyl acetate and ethyl acetate and a line for the methanol stream S301 are connected to a feed inlet of the methanol recovery column T4 for separating the methanol stream S201 containing methyl acetate and ethyl acetate and the methanol stream S301 containing methanol into the methanol recovery column T4, a stream S401 containing methyl acetate and ethyl acetate is taken out from the top of the column, and a methanol product S402 is taken out from the bottom of the column.
The purity of the methanol product S402 obtained is 85-99.999%.
In one embodiment, as shown in fig. 2, the rectification separation system further comprises an ethanol recovery tower T5, a pipeline of the heavy component stream S303 is connected with a feed inlet of the ethanol recovery tower T5 for separating the heavy component stream S303 into the ethanol recovery tower T5, a recovered ethanol stream S501 is withdrawn from the top of the tower, and a heavy impurity stream S502 is withdrawn from the bottom of the tower.
In one embodiment, as shown in fig. 1 and 2, the separation device further comprises a molecular sieve adsorption and dehydration system A1, and the pipeline of the hydrous ethanol product S302 is connected with the feed inlet of the molecular sieve adsorption and dehydration system A1 for obtaining an absolute ethanol product S601 and wastewater S602.
The purity of the separated ethanol product S601 is 90-99.999%.
The separation device can thoroughly separate ethanol from other components to obtain a purer ethanol product.
In one embodiment, the line for recovering ethanol stream S501 is connected to the feed inlet of ethanol column T3 for separating recovered ethanol stream S501 into ethanol column T3 for recovering ethanol.
Preferably, the line for recovering ethanol stream S501 is connected to the feed inlet in the middle or lower part of ethanol column T3 for separating recovered ethanol stream S501 into ethanol column T3 for recovering ethanol.
In one embodiment, the ethanol column T3 is a baffle rectification column, as shown in fig. 3, in which a vertical baffle is provided to divide the column into a1 st zone for feeding, a2 nd zone for public rectification, a 3 rd zone for discharging and a 4 th zone for public stripping, preferably, a pipeline of the ethanol stream S202 containing the remaining part of methanol is connected with the 1 st zone of the ethanol column T3, a methanol-containing stream S301 is withdrawn from the 2 nd zone, an aqueous ethanol product S302 is withdrawn from the 3 rd zone, a heavy component stream S303 is withdrawn from the 4 th zone, and preferably, a pipeline of the recovered ethanol stream S501 is connected with the 4 th zone or the 1 st zone (not shown in fig. 2) of the ethanol column T3.
In one embodiment, the top of the pre-separation tower T2 is connected with reboilers E302 and E402 of the ethanol tower T3 and the methanol recovery tower T4 respectively through pipelines so as to take the steam at the top of the pre-separation tower T2 as a heat source of the reboilers of the ethanol tower T3 and the methanol recovery tower T4.
In one embodiment, the operating pressure of the degasser is from 1 to 1000kPa and the reflux ratio is from 1 to 50; the operation pressure of the pre-separation tower is 1-1000kPa, and the reflux ratio is 1-20; the operating pressure of the ethanol 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 1-10.
According to the invention, the tower top steam of the pre-separation tower is used for heating 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, so that the heat source energy consumption is saved.
The invention adopts the process of combining the partition wall rectification technology and the double-effect rectification technology, thereby not only improving the separation efficiency, but also saving the operation energy consumption to the greatest extent.
In one embodiment, a condenser E101 is provided between the top of the degasser T1 and the lights stream S102, and a reboiler E102 is provided at the bottom.
In one embodiment, a condenser E501 is provided between the top of the ethanol recovery column T5 and the recovered ethanol stream S501, and a reboiler E502 is provided at the bottom of the column.
In one embodiment, a reboiler E202 is provided at the bottom of the pre-separation column T2, a condenser E301 is provided between the top of the ethanol column T3 and the methanol-containing stream S301, and a condenser E401 is provided between the top of the methanol recovery column T4 and the methyl acetate-and ethyl acetate-containing stream S401.
In one embodiment, the internals of the ethanol column T3 may be in the form of a pure packed column, a pure tray column, or a composite of packed and tray columns.
Examples
The materials used in the test and the test methods are described generally and/or specifically in the examples which follow,% represents wt%, i.e. weight percent, unless otherwise specified. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
Example 1
The separation was carried out using the apparatus shown in FIG. 1 at a flow rate of 72t/h, wherein the dimethyl ether-to-ethanol reaction product stream S101 comprises 41wt% of methanol, 52wt% of ethanol, 5wt% of methyl acetate and ethyl acetate, 1wt% of water, 0.5wt% of a heavy alcohol such as propanol, and 0.5wt% of a light component such as dimethyl ether, and the like.
The separation device comprises a rectification separation system (not shown in the figure) and a molecular sieve adsorption dehydration system A1, wherein the rectification separation system comprises a degasser T1, a pre-separation tower T2, an ethanol tower T3 and a methanol recovery tower T4;
A pipeline of the reaction product stream S101 for preparing the ethanol by the dimethyl ether is connected with a feed inlet of the degasser T1 for separating the reaction product stream S101 for preparing the ethanol by the dimethyl ether into the degasser T1, a light component stream S102 is extracted from the top of the degasser T1, and a bottom stream S103 is extracted from the bottom of the degasser T1;
The pipeline of the tower bottom material S103 is connected with the feed inlet of the pre-separation tower T2, so that the tower bottom material S103 enters the pre-separation tower T2 for separation, a methanol material S201 containing methyl acetate and ethyl acetate is extracted from the tower top of the pre-separation tower T2, and an ethanol material S202 containing the rest part of methanol is extracted from the tower bottom;
the ethanol tower T3 is a baffle rectifying tower (a packed tower), as shown in fig. 3, a vertical baffle is arranged in the baffle rectifying tower to divide the tower into a1 st zone for feeding, a2 nd zone for public rectification, a 3 rd zone for discharging and a 4 th zone for public stripping, a pipeline of an ethanol stream S202 containing the rest part of methanol is connected with the 1 st zone of the ethanol tower T3, a methanol-containing stream S301 is extracted from the 2 nd zone, an aqueous ethanol product S302 is extracted from the 3 rd zone, and a heavy component stream S303 is extracted from the 4 th zone;
A pipeline of a methanol stream S201 containing methyl acetate and ethyl acetate and a pipeline of a methanol stream S301 are connected with a feed inlet of the methanol recovery tower T4 for separating the methanol stream S201 containing methyl acetate and ethyl acetate and the methanol stream S301 containing methanol into the methanol recovery tower T4, a stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and a methanol product S402 is extracted from the bottom of the tower;
The pipeline of the hydrous ethanol product S302 is connected with the feed inlet of a molecular sieve adsorption dehydration system A1 to obtain an anhydrous ethanol product S601 and wastewater S602, and the molecular sieve dehydration system comprises evaporation, adsorption and desorption, condensation equipment and a 3A molecular sieve;
the top of the pre-separation tower T2 is respectively connected with reboilers E302 and E402 of an ethanol tower T3 and a methanol recovery tower T4 through pipelines, so that steam at the top of the pre-separation tower T2 is used as a heat source of the reboilers of the ethanol tower T3 and the methanol recovery tower T4;
A condenser E101 is arranged between the top of the degasser T1 and the light component stream S102, and a reboiler E102 is arranged at the bottom of the degasser T1;
A reboiler E202 is arranged at the bottom of the pre-separation tower T2, a condenser E301 is arranged between the top of the ethanol tower T3 and a methanol-containing stream S301, and a condenser E401 is arranged between the top of the methanol recovery tower T4 and a stream S401 containing methyl acetate and ethyl acetate.
The separation method comprises the following steps:
(1) The reaction product stream S101 from the ethanol preparation of dimethyl ether enters a degasser T1 for separation, the operating pressure of the degasser T1 is 300kPa, the reflux ratio is 3.55, a light component stream S102 is extracted from the top of the tower, a bottom stream S103 is extracted from the bottom of the tower, the light component stream S102 comprises light components such as dimethyl ether, and the light component stream is returned to an upstream reaction system for continuous reaction;
(2) The bottom material flow S103 enters a pre-separation tower T2 for separation, the operation pressure of the pre-separation tower T2 is 180kPa, the reflux ratio is 2.97, a methanol material flow S201 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and an ethanol material flow S202 containing the rest part of methanol is extracted from the bottom of the tower;
(3) The ethanol stream S202 containing the rest part of methanol enters an ethanol tower T3 for separation, the operating pressure of the ethanol tower T3 is 40kPa, the reflux ratio is 13.31, the methanol-containing stream S301 is extracted from a zone 2, the aqueous ethanol product S302 is extracted from a zone 3, and the heavy component stream S303 is extracted from a zone 4;
(4) Separating the methanol stream S201 containing methyl acetate and ethyl acetate from the methanol stream S301 containing methyl acetate in a methanol recovery tower T4, wherein the operating pressure of the methanol recovery tower T4 is 50kPa, the reflux ratio is 7.00, a stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, a methanol product S402 is extracted from the bottom of the tower, and the stream S401 containing methyl acetate and ethyl acetate is returned to an upstream reaction system for continuous reaction;
(5) The hydrous ethanol product S302 enters a molecular sieve adsorption dehydration system A1 for dehydration to obtain an anhydrous ethanol product S601 and wastewater S602;
After the separation method and the separation device are used 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 aqueous ethanol product is 400ppm, the weight alcohol content is 200ppm, the ethanol purity is 99.9%, and the dehydration effect of the molecular sieve adsorption dehydration system meets the GB/T678-2002-absolute ethanol standard.
Wherein the heat load, operating pressure and reflux ratios for each column are shown in table 1.
TABLE 1 Heat load, operating pressure and reflux ratio for each column
| Column 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 | |
| Column operating pressure | KPA | 300 | 180 | 40 | 50 |
As can be seen from Table 1, the total heat load for external application was 31.16MKCAL/HR.
Example 2
The separation was performed using the apparatus shown in fig. 2 at the same flow rate as 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., wherein the methanol is 51wt%, the ethanol is 42wt%, the methyl acetate and ethyl acetate are 5wt%, the water is 1wt%, the heavy alcohols such as propanol are 0.5wt%, and the light components such as dimethyl ether are 0.5wt%.
The separation device comprises a rectification separation system (not shown in the figure) and a molecular sieve adsorption dehydration system A1, wherein the rectification separation system comprises a degasser T1, a pre-separation tower T2, an ethanol tower T3, a methanol recovery tower T4 and an ethanol recovery tower T5;
A pipeline of the reaction product stream S101 for preparing the ethanol by the dimethyl ether is connected with a feed inlet of the degasser T1 for separating the reaction product stream S101 for preparing the ethanol by the dimethyl ether into the degasser T1, a light component stream S102 is extracted from the top of the degasser T1, and a bottom stream S103 is extracted from the bottom of the degasser T1;
the pipeline of the bottom stream S103 is connected with the feed inlet of the pre-separation tower T2, so that the bottom stream S103 enters the pre-separation tower T2 for separation, a methanol stream S201 containing methyl acetate and ethyl acetate is extracted from the top of the pre-separation tower T2, and an ethanol stream S202 containing the rest part of methanol is extracted from the bottom of the pre-separation tower T2;
the ethanol tower T3 is a baffle rectifying tower (a packed tower), as shown in fig. 3, a vertical baffle is arranged in the baffle rectifying tower to divide the tower into a1 st zone for feeding, a2 nd zone for public rectification, a 3 rd zone for discharging and a 4 th zone for public stripping, a pipeline of an ethanol stream S202 containing the rest part of methanol is connected with the 1 st zone of the ethanol tower T3, a methanol-containing stream S301 is extracted from the 2 nd zone, an aqueous ethanol product S302 is extracted from the 3 rd zone, and a heavy component stream S303 is extracted from the 4 th zone;
A pipeline of a methanol stream S201 containing methyl acetate and ethyl acetate and a pipeline of a methanol stream S301 are connected with a feed inlet of the methanol recovery tower T4 for separating the methanol stream S201 containing methyl acetate and ethyl acetate and the methanol stream S301 containing methanol into the methanol recovery tower T4, a stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and a methanol product S402 is extracted from the bottom of the tower;
The pipeline of the hydrous ethanol product S302 is connected with the feed inlet of a molecular sieve adsorption dehydration system A1 to obtain an anhydrous ethanol product S601 and wastewater S602, and the molecular sieve dehydration system comprises evaporation, adsorption and desorption, condensation equipment and a 3A molecular sieve;
The pipeline of the heavy component stream S303 is connected with the feed inlet of the ethanol recovery tower T5 for separating the heavy component stream S303 into the ethanol recovery tower T5, recovering the ethanol stream S501 from the top of the tower, and recovering the heavy impurity stream S502 from the bottom of the tower;
The pipeline for recovering the ethanol stream S501 is connected with the feed inlet at the middle lower part of the ethanol tower T3 for separating the recovered ethanol stream S501 into the ethanol tower T3 for recovering ethanol;
the top of the pre-separation tower T2 is respectively connected with reboilers E302 and E402 of an ethanol tower T3 and a methanol recovery tower T4 through pipelines, so that steam at the top of the pre-separation tower T2 is used as a heat source of the reboilers of the ethanol tower T3 and the methanol recovery tower T4;
A condenser E101 is arranged between the top of the degasser T1 and the light component stream S102, and a reboiler E102 is arranged at the bottom of the degasser T1;
A reboiler E202 is arranged at the bottom of the pre-separation tower T2, a condenser E301 is arranged between the top of the ethanol tower T3 and a methanol-containing stream S301, and a condenser E401 is arranged between the top of the methanol recovery tower T4 and a stream S401 containing methyl acetate and ethyl acetate;
A condenser E501 is provided between the top of the ethanol recovery column T5 and the recovered ethanol stream S501, and a reboiler E502 is provided at the bottom of the column.
The separation method comprises the following steps:
(1) The reaction product stream S101 from the ethanol preparation of dimethyl ether enters a degasser T1 for separation, the operating pressure of the degasser T1 is 300kPa, the reflux ratio is 3.55, a light component stream S102 is extracted from the top of the tower, a bottom stream S103 is extracted from the bottom of the tower, the light component stream S102 comprises light components such as dimethyl ether, and the light component stream is returned to an upstream reaction system for continuous reaction;
(2) The bottom material flow S103 enters a pre-separation tower T2 for separation, the operation pressure of the pre-separation tower T2 is 160kPa, the reflux ratio is 2.73, a methanol material flow S201 containing methyl acetate and ethyl acetate is extracted from the top of the tower, and an ethanol material flow S202 containing the rest part of methanol is extracted from the bottom of the tower;
(3) The ethanol stream S202 containing the rest part of methanol enters an ethanol tower T3 for separation, the operating pressure of the ethanol tower T3 is 110kPa, the reflux ratio is 10.61, a methanol-containing stream S301 is extracted from a zone 2, an aqueous ethanol product S302 is extracted from a zone 3, and a heavy component stream S303 is extracted from a zone 4;
(4) Separating the methanol stream S201 containing methyl acetate and ethyl acetate from the methanol stream S301 containing methyl acetate in a methanol recovery tower T4, wherein the operating pressure of the methanol recovery tower T4 is 110kPa, the reflux ratio is 7.00, a stream S401 containing methyl acetate and ethyl acetate is extracted from the top of the tower, a methanol product S402 is extracted from the bottom of the tower, and the stream S401 containing methyl acetate and ethyl acetate is returned to an upstream reaction system for continuous reaction;
(5) The hydrous ethanol product S302 enters a molecular sieve adsorption dehydration system A1 for dehydration to obtain an anhydrous ethanol product S601 and wastewater S602;
(6) The heavy component stream S303 enters an ethanol recovery tower T5 for separation, the operating pressure of the ethanol recovery tower T5 is 200kPa, the reflux ratio is 2.00, a recovered ethanol stream S501 is extracted from the top of the tower, and a heavy impurity stream S502 is extracted from the bottom of the tower; the recovered ethanol stream S501 enters the ethanol column T3 to continue the separation.
After the separation method and the separation device are used 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 aqueous ethanol product is 400ppm, the weight alcohol content is 200ppm, the ethanol purity is 99.9%, and the dehydration effect of the molecular sieve adsorption dehydration system meets the GB/T678-2002-absolute ethanol standard.
Wherein the heat load, operating pressure and reflux ratios for each column are shown in table 2.
TABLE 2 Heat load, operating pressure and reflux ratio for each column
| Column 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 | |
| Column operating pressure | KPA | 300 | 260 | 110 | 200 | 110 |
As can be seen from Table 2, the total heat load for external use was 35.74MKCAL/HR
In summary, the separation method provided by the invention is adopted to separate the ethanol product and the methanol product, the purity of the obtained ethanol product and the methanol product is higher, the separation effect is good, and the energy consumption of operation is reduced to the greatest extent by adopting a mode of combining a partition wall fractionation technology and a double-effect distillation technology, so that the purpose of energy conservation is achieved.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (9)
1. The separation method for preparing ethanol from dimethyl ether is characterized by comprising the following steps of:
The method comprises the steps that a reaction product of preparing ethanol from dimethyl ether enters a rectification separation system to obtain an aqueous ethanol product, wherein the rectification separation system comprises a degassing tower, a pre-separation tower, an ethanol tower and a methanol recovery tower, the reaction product of preparing ethanol from dimethyl ether enters the degassing tower, a light component material flow is extracted from the top of the tower, and a bottom material flow is extracted from the bottom of the tower;
The bottom stream enters a pre-separation tower to be separated, a methanol stream containing methyl acetate and ethyl acetate is extracted from the top of the tower, and an ethanol stream containing the rest part of methanol is extracted from the bottom of the tower;
the ethanol stream containing the rest part of methanol enters an ethanol tower for separation, an aqueous ethanol product is extracted from the side line of the tower, a methanol-containing stream is extracted from the top of the tower, and a heavy component stream is extracted from the bottom of the tower;
separating a methanol stream containing methyl acetate and ethyl acetate extracted from the top of the pre-separation tower and a methanol stream containing methyl acetate and ethyl acetate extracted from the top of the ethanol tower in a methanol recovery tower, extracting a stream containing methyl acetate and ethyl acetate from the top of the ethanol tower, and extracting a methanol product from the bottom of the ethanol tower;
The tower top steam of the pre-separation tower is used as a reboiler heat source of the ethanol tower and the methanol recovery tower;
the ethanol tower is a partition rectifying tower;
the operating pressure of the degasser is 1-1000kPa, and the reflux ratio is 1-50;
The operation pressure of the pre-separation tower is 1-1000kPa, and the reflux ratio is 1-20;
the operating pressure of the ethanol tower is 1-1000kPa, and the reflux ratio is 1-100;
the operating pressure of the methanol recovery tower is 1-1000kPa, and the reflux ratio is 1-10.
2. The separation method according to claim 1, wherein the rectification separation system further comprises an ethanol recovery column, the heavy component stream withdrawn from the bottom of the ethanol column is fed into the ethanol recovery column for separation, and the recovered ethanol stream is withdrawn from the top of the ethanol column.
3. The separation method according to claim 1, wherein the absolute ethanol product is obtained after the aqueous ethanol product is introduced into a molecular sieve adsorption dehydration system.
4. The separation process of claim 2 wherein the recovered ethanol stream withdrawn from the top of the ethanol recovery column is passed to an ethanol column for separation.
5. The separation method of claim 1, 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 claim 5, wherein the methanol is 30-70% and the ethanol is 30-70% based on the mass percentage of the reaction product of dimethyl ether to ethanol.
7. The separation process of claim 2, wherein the ethanol recovery column operates at a pressure of from 1 kPa to 1000kPa.
8. The separation process according to any one of claims 1 to 7, wherein the absolute ethanol product has a purity of 90 to 99.999%.
9. The separation process according to any one of claims 1 to 7, wherein the methanol product has a purity of 85 to 99.999%.
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