CN115364502A - Thermal coupling separation device and separation method for methyl acetate hydrogenation product - Google Patents
Thermal coupling separation device and separation method for methyl acetate hydrogenation product Download PDFInfo
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- CN115364502A CN115364502A CN202210997348.7A CN202210997348A CN115364502A CN 115364502 A CN115364502 A CN 115364502A CN 202210997348 A CN202210997348 A CN 202210997348A CN 115364502 A CN115364502 A CN 115364502A
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- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 title claims abstract description 73
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 title claims abstract description 71
- 238000005984 hydrogenation reaction Methods 0.000 title claims abstract description 47
- 238000000926 separation method Methods 0.000 title claims abstract description 44
- 230000008878 coupling Effects 0.000 title claims abstract description 20
- 238000010168 coupling process Methods 0.000 title claims abstract description 20
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 20
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 1374
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 577
- 238000010992 reflux Methods 0.000 claims abstract description 126
- 238000007257 deesterification reaction Methods 0.000 claims abstract description 116
- 239000000463 material Substances 0.000 claims abstract description 35
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 81
- 238000000034 method Methods 0.000 claims description 32
- 239000000126 substance Substances 0.000 claims description 28
- 238000009833 condensation Methods 0.000 claims description 12
- 230000005494 condensation Effects 0.000 claims description 12
- 239000007789 gas Substances 0.000 description 21
- 239000007788 liquid Substances 0.000 description 11
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 8
- 238000005265 energy consumption Methods 0.000 description 6
- 238000009835 boiling Methods 0.000 description 5
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- 239000002737 fuel gas Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000003502 gasoline Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Natural products CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000006315 carbonylation Effects 0.000 description 1
- 238000005810 carbonylation reaction Methods 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 208000012839 conversion disease Diseases 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- ZQBVUULQVWCGDQ-UHFFFAOYSA-N propan-1-ol;propan-2-ol Chemical compound CCCO.CC(C)O ZQBVUULQVWCGDQ-UHFFFAOYSA-N 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
-
- 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
- C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
- C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
- C07C29/147—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof
- C07C29/149—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof with hydrogen or hydrogen-containing gases
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a thermal coupling separation device and a separation method for a methyl acetate hydrogenation product. The device comprises: a deesterification tower, a high-pressure methanol tower, a low-pressure methanol tower and an ethanol tower; the bottom discharge hole of the deesterification tower is connected with the middle feed inlet of the high-pressure methanol tower, the bottom discharge hole of the high-pressure methanol tower is connected with the middle feed inlet of the low-pressure methanol tower, and the bottom discharge hole of the low-pressure methanol tower is connected with the middle feed inlet of the ethanol tower, or the bottom discharge hole of the deesterification tower is respectively connected with the middle feed inlet of the high-pressure methanol tower and the middle feed inlet of the low-pressure methanol tower, and the bottom discharge hole of the high-pressure methanol tower and the bottom discharge hole of the low-pressure methanol tower are respectively connected with the middle feed inlet of the ethanol tower; the top discharge port of the high-pressure methanol tower is connected with the hot side inlet of the reboiler of the low-pressure methanol tower, the hot side outlet of the reboiler of the low-pressure methanol tower is connected with the top reflux port of the high-pressure methanol tower, and the hot side outlet of the reboiler of the low-pressure methanol tower is also used for outputting materials outwards.
Description
Technical Field
The invention belongs to the technical field of comprehensive utilization of tail gas in chemical industry, coal chemical industry, coking and steelmaking, and particularly relates to a thermal coupling separation device and a separation method for a methyl acetate hydrogenation product.
Background
At present, the consumption of ethanol gasoline is increasing day by day, and the gap of the production raw material bioethanol production capacity of the ethanol gasoline is large, so that the coal-based ethanol becomes an important production raw material of the ethanol gasoline.
In a plurality of coal-to-ethanol processes, the process routes of preparing methyl acetate from synthesis gas through dimethyl ether carbonylation and preparing ethanol from methyl acetate through hydrogenation have high reaction conversion rate and good selectivity of ethanol generation, and compared with other process routes, the process can effectively reduce equipment investment and energy consumption.
The methyl acetate hydrogenation product mainly comprises dimethyl ether, methyl acetate, ethyl acetate, methanol, ethanol, 1-2% of water and trace C3-C4 alcohol. The boiling points of the components are close, the relative volatility is small, and a plurality of groups of azeotropes are formed (the boiling points of the components under normal pressure are shown in table 1), so that the separation difficulty of the components is high, the energy consumption is high (the energy consumption ratio of steam supply is the largest), and the production cost of the product ethanol is high.
TABLE 1
| Main component | Atmospheric boiling point (. Degree. C.) |
| Acetic acid methyl esterMethanol azeotrope | 53.6 |
| Acetic acid methyl ester | 57.8 |
| Ethyl acetate/methanol azeotrope | 62.3 |
| Methanol | 64.7 |
| Ethyl acetate/ethanol | 71.8 |
| Ethyl acetate | 77.2 |
| Ethanol/water azeotropes | 78.1 |
| Ethanol | 78.3 |
| Isopropanol (I-propanol) | 82.5 |
The prior art ethanol separation technology in methyl acetate hydrogenation products generally adopts a 4-tower flow path, which comprises the following steps: a light component removing tower, a methanol tower, an ethanol tower and an ethanol recovery tower. The prior technology for separating ethanol from methyl acetate hydrogenation products generally adopts the following two process flows:
a process flow comprises the following steps: firstly, taking out methyl acetate and ethyl acetate through azeotropy by methanol in a light component removal tower under the rectification action, separating methanol with the purity of 55-60% at the top of a methanol tower, separating methanol at the top of the ethanol tower under the rectification action, extracting an ethanol product from a side line, taking a tower bottom liquid as a mixture of ethanol and C3-C4 alcohol, extracting recovered ethanol from the top of an ethanol recovery tower, returning the ethanol to the ethanol tower to serve as a side line supplementary feed of a stripping section, and discharging kettle residual liquid containing C3+ alcohols from a tower bottom discharge pipeline of the ethanol recovery tower.
The other process flow is as follows: cutting ethyl acetate in a light component removing tower, extracting methanol and ethyl acetate from the top of the tower in an ethanol tower, and separating and purifying the methanol and the ethanol in a methanol tower and an ethanol recovery tower respectively.
The existing ethanol separation technology in methyl acetate hydrogenation products has high steam consumption and high cost.
Disclosure of Invention
The invention aims to provide a device and a method for effectively separating ethanol, methanol and C3+ alcohol (mainly C3-C4 alcohol) while reducing the use amount of steam.
In order to achieve the above object, the present invention provides the following three aspects.
In a first aspect, the present invention provides a thermally coupled separation unit for a methyl acetate hydrogenation product, wherein the unit comprises:
a deesterification tower, a high-pressure methanol tower, a low-pressure methanol tower and an ethanol tower; wherein the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower are respectively provided with a top discharge hole, a top reflux hole, a middle feed hole, a bottom discharge hole and a reboiler;
the bottom discharge hole of the deesterification tower is connected with the middle feed inlet of the high-pressure methanol tower, the bottom discharge hole of the high-pressure methanol tower is connected with the middle feed inlet of the low-pressure methanol tower, the bottom discharge hole of the low-pressure methanol tower is connected with the middle feed inlet of the ethanol tower, and the high-pressure methanol tower and the low-pressure methanol tower are connected in series at the moment; or the bottom discharge port of the deesterification tower is respectively connected with the middle feed port of the high-pressure methanol tower and the middle feed port of the low-pressure methanol tower, the bottom discharge port of the high-pressure methanol tower and the bottom discharge port of the low-pressure methanol tower are respectively connected with the middle feed port of the ethanol tower, and the high-pressure methanol tower and the low-pressure methanol tower are connected in parallel;
a discharge port at the top of the high-pressure methanol tower is connected with a hot side inlet of a reboiler of the low-pressure methanol tower, and a hot side outlet of the reboiler of the low-pressure methanol tower is connected with a top reflux port of the high-pressure methanol tower; wherein, the hot side outlet of the reboiler of the low-pressure methanol tower is also used for outputting materials outwards;
the middle feed inlet of the deesterification tower is used for supplying methyl acetate hydrogenation products to the deesterification tower; the top reflux port of the deesterification tower is used for refluxing to the deesterification tower, and reflux liquid is from a condensate flow of gas output by the top discharge port of the deesterification tower; the top reflux port of the low-pressure methanol tower is used for refluxing to the low-pressure methanol tower, and reflux liquid is a condensate flow of gas output from the top discharge port of the low-pressure methanol tower; the top reflux port of the ethanol tower is used for refluxing to the ethanol tower, and reflux liquid is a condensate flow of gas output from the top discharge port of the ethanol tower.
According to a preferred embodiment provided by the first aspect, a pump is arranged on a connecting pipeline between a hot side outlet of a reboiler of the low pressure methanol tower and a top reflux port of the high pressure methanol tower.
According to the first aspect, a top discharge port of the low-pressure methanol tower is connected with a hot side inlet of a reboiler of the ethanol tower, and a hot side outlet of the reboiler of the ethanol tower is connected with a top reflux port of the low-pressure methanol tower; wherein, the hot side outlet of the reboiler of the ethanol tower is also used for outputting materials outwards;
further, a pump is arranged on a connecting pipeline between a discharge port at the top of the low-pressure methanol tower and an inlet at the hot side of a reboiler of the ethanol tower;
further, the reboiler of the ethanol column comprises a first reboiler and a second reboiler; a discharge port at the top of the low-pressure methanol tower is connected with a hot side inlet of a first reboiler of the ethanol tower, and a hot side outlet of the first reboiler of the ethanol tower is connected with a top reflux port of the low-pressure methanol tower (wherein the hot side outlet of the first reboiler of the ethanol tower is also used for outputting materials outwards); the hot side inlet of the second reboiler of the ethanol column is adapted to be connected to a heat source supply, such as a steam supply.
According to a preferred embodiment of the first aspect, a hot side inlet of the reboiler of the deesterification column is adapted to be connected to a heat source supply (e.g. a steam supply).
According to a preferred embodiment provided by the first aspect, the hot side inlet of the reboiler of the high pressure methanol column is adapted to be connected to a heat source supply (e.g. a steam supply).
According to a preferred embodiment provided by the first aspect, the apparatus is further provided with a depolymer column, and the depolymer column is connected with a top discharge port of the depolymer column and a top reflux port of the depolymer column respectively.
According to a preferred embodiment provided by the first aspect, the apparatus is further provided with an ethanol column condenser, and the ethanol column condenser is respectively connected with the top discharge port of the ethanol column and the top reflux port of the ethanol column.
According to a preferred embodiment provided by the first aspect, wherein the high pressure methanol column is connected in parallel with the low pressure methanol column, the deesterification column is arranged to effect separation of a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope in the methyl acetate hydrogenation product; the high-pressure methanol tower is used for separating methanol; the low-pressure methanol tower is used for separating methanol; the ethanol tower is used for separating ethanol;
at the moment, a discharge hole at the top of the ethanol tower is used for outputting ethanol outwards; a discharge hole at the bottom of the ethanol tower is used for outputting C3+ alcohol (mainly C3-C4 alcohol); a discharge hole at the top of the low-pressure methanol tower is used for outputting methanol outwards; the hot side outlet of the reboiler of the low-pressure methanol tower is used for outputting methanol outwards;
further, the deesterification column can be used to perform a micro-positive pressure rectification; further, the deesterification column can be used to perform rectification at pressures of 100 to 400kPa, reflux ratios of 8 to 12, theoretical plate numbers of 60 to 90; still further, the deesterification column can be used to carry out rectification at pressures of 120-200kPa, reflux ratios of 9-11, and theoretical plate numbers of 70-80;
further, the high pressure methanol column can be used for pressure rectification; further, the high pressure methanol column can be used for rectification at pressures of 300-700kPa, reflux ratios of 4-6, and theoretical plate numbers of 75-100 (in one embodiment, the theoretical plate number is greater than 80 and less than or equal to 100); still further, the high pressure methanol column can be used for rectification at a pressure of 450-600kPa, a reflux ratio of 4-5, and a theoretical plate number of 80-90 (in one embodiment, the theoretical plate number is greater than 80 and equal to or less than 90);
further, the low pressure methanol column can be used for micro positive pressure rectification; further, the low pressure methanol column can be used for rectification at 100-250kPa pressure, 3-5 reflux ratio, 70-90 theoretical plate number; still further, the low-pressure methanol column can be used for rectification under the pressure of 130-180kPa, the reflux ratio of 3-4 and the theoretical plate number of 80-90;
further, the ethanol column can be used to perform vacuum rectification; further, the ethanol column can be used for rectification under the pressure of 5-100kPa, the reflux ratio of 0.8-2.5 and the theoretical plate number of 50-70; still further, the ethanol column can be used to perform rectification at pressures of 10-40kPa, reflux ratios of 1-2, and theoretical plate numbers of 55-65.
According to a preferred embodiment provided by the first aspect, wherein the high pressure methanol column is in series with the low pressure methanol column, the deesterification column is arranged to effect separation of a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope in the methyl acetate hydrogenation product; the high-pressure methanol tower is used for separating partial methanol; the low-pressure methanol tower is used for separating the residual methanol; the ethanol tower is used for separating ethanol;
at the moment, a discharge hole at the top of the ethanol tower is used for outputting ethanol outwards; a discharge hole at the bottom of the ethanol tower is used for outputting C3+ alcohol (mainly C3-C4 alcohol) outwards; a discharge hole at the top of the low-pressure methanol tower is used for outputting methanol outwards; the hot side outlet of the reboiler of the low-pressure methanol tower is used for outputting methanol outwards;
further, the deesterification column can be used for carrying out micro-positive pressure rectification; further, the deesterification column can be used to perform rectification at pressures of 100 to 400kPa, reflux ratios of 8 to 12, theoretical plate numbers of 60 to 90; still further, the deesterification column can be used to perform a rectification at a pressure of 120 to 200kPa, a reflux ratio of 9 to 11, and a theoretical plate number of 70 to 80;
further, the high pressure methanol column can be used for pressure rectification; further, the high pressure methanol column can be used to perform rectification at pressures of 300-700kPa, reflux ratios of 4-6, theoretical plate counts of 60-90 (in one embodiment, theoretical plate counts of 60-80); still further, the high pressure methanol column can be used for rectification under the pressure of 450-600kPa, the reflux ratio of 4-5 and the theoretical plate number of 70-80;
further, the low pressure methanol column can be used for micro positive pressure rectification; further, the low pressure methanol tower can be used for rectification under the pressure of 100-250kPa, the reflux ratio of 5-8 and the theoretical plate number of 100-140; still further, the low pressure methanol column can be used for rectification under 130-180kPa pressure, 6-7 reflux ratio, 110-130 theoretical plate number;
further, the ethanol column can be used to perform vacuum rectification; further, the ethanol column can be used for rectification under the pressure of 5-100kPa, the reflux ratio of 0.8-2.5 and the theoretical plate number of 50-70; still further, the ethanol column can be used to perform rectification at pressures of 10-40kPa, reflux ratios of 1-2, and theoretical plate numbers of 55-65.
According to a preferred embodiment provided by the first aspect, wherein the temperature difference between the top of the high-pressure methanol column and the bottom of the low-pressure methanol column can be controlled to 10 to 15 ℃.
According to a preferred embodiment provided by the first aspect, the temperature difference between the top of the low-pressure methanol column and the bottom of the ethanol column can be controlled to 10 to 15 ℃.
In a second aspect, the present invention also provides a methyl acetate hydrogenation product thermal coupling separation method, which is performed by using the above methyl acetate hydrogenation product thermal coupling separation device, and comprises:
the methyl acetate hydrogenation product enters a deesterification tower through a middle feed inlet of the deesterification tower for rectification, a tower top separated substance containing a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope is output from a discharge outlet at the top of the deesterification tower, and a tower bottom separated substance containing methanol, ethanol and C3+ alcohol is output from a discharge outlet at the bottom of the deesterification tower;
one part of the tower bottom separated substance containing methanol, ethanol and C3+ alcohol output from the bottom discharge hole of the deesterification tower enters the high-pressure methanol tower through the middle feed inlet of the high-pressure methanol tower for rectification, the other part enters the low-pressure methanol tower through the middle feed inlet of the low-pressure methanol tower for rectification, methanol products are output from the top discharge holes of the high-pressure methanol tower and the low-pressure methanol tower, and the tower bottom separated substance containing ethanol and C3+ alcohol is output from the bottom discharge holes of the high-pressure methanol tower and the low-pressure methanol tower; the method comprises the following steps that (1) tower bottom isolates containing ethanol and C3+ alcohol, which are output from bottom discharge ports of a high-pressure methanol tower and a low-pressure methanol tower, enter an ethanol tower through a middle feed port of the ethanol tower to be rectified, ethanol products are output from a top discharge port of the ethanol tower, and C3+ alcohol products are output from a bottom discharge port of the ethanol tower;
wherein, the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation heat exchange;
in this case, the high-pressure methanol column and the low-pressure methanol column are connected in parallel.
In the thermally coupled separation method of the methyl acetate hydrogenation product provided by the second aspect, a part of the material flows output from the top discharge ports of the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower need to be refluxed into the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower through the top reflux ports.
According to a preferred embodiment provided by the second aspect, the heat source of the reboiler of the low pressure methanol column is a stream in the top outlet of the high pressure methanol column.
According to a preferred embodiment provided by the second aspect, wherein the heat source of the reboiler of the deesterification column is steam.
According to a preferred embodiment provided by the second aspect, wherein the heat source of the reboiler of the high pressure methanol column is steam.
According to the second aspect, a preferable embodiment is provided, wherein the stream in the top discharge port of the low-pressure methanol tower enters the reboiler of the ethanol tower in a gas phase for condensation heat exchange;
further, the heat source of the reboiler of the ethanol tower is material flow and steam in a discharge hole at the top of the low-pressure methanol tower;
furthermore, the proportion of the reboiler of the ethanol tower adopting steam as a heat source is not higher than 25% of the total heat load of the reboiler of the ethanol tower.
According to a preferred embodiment provided by the second aspect, the temperature difference between the top of the high pressure methanol column and the bottom of the low pressure methanol column is 10 to 15 ℃.
According to a preferred embodiment provided by the second aspect, wherein the temperature difference between the top of the low pressure methanol column and the bottom of the ethanol column is 10-15 ℃.
According to a preferred embodiment provided by the second aspect, the rectification performed in the deesterification column is a slight positive pressure rectification;
further, the operating pressure of the deesterification tower is 100-400kPa, the reflux ratio is 8-12, and the theoretical plate number is 60-90;
further, the operating pressure of the deesterification tower is 120-200kPa, the reflux ratio is 9-11, and the theoretical plate number is 70-80.
According to a preferred embodiment provided by the second aspect, the rectification performed in the high pressure methanol column is pressure rectification;
further, the operating pressure of the high-pressure methanol tower is 300-700kPa, the reflux ratio is 4-6, and the number of theoretical plates is 75-100; in one embodiment, the high pressure methanol column has an operating pressure of 300 to 700kPa, a reflux ratio of 4 to 6, and a theoretical plate number of greater than 80 and equal to or less than 100;
furthermore, the operating pressure of the high-pressure methanol tower is 450-600kPa, the reflux ratio is 4-5, and the number of theoretical plates is 80-90; in one embodiment, the high pressure methanol column has an operating pressure of 300 to 700kPa, a reflux ratio of 4 to 6, and a theoretical plate number of greater than 80 and equal to or less than 90.
According to a preferred embodiment provided by the second aspect, the rectification performed in the low pressure methanol column is pressure rectification;
further, the operating pressure of the low-pressure methanol tower is 100-250kPa, the reflux ratio is 3-5, and the number of theoretical plates is 70-90;
furthermore, the operating pressure of the low-pressure methanol tower is 130-180kPa, the reflux ratio is 3-4, and the number of theoretical plates is 80-90;
according to a preferred embodiment provided by the second aspect, the rectification performed in the ethanol column is vacuum rectification;
further, the operating pressure of the ethanol tower is 5-100kPa, the reflux ratio is 0.8-2.5, and the number of theoretical plates is 50-70;
furthermore, the operating pressure of the ethanol tower is 10-40kPa, the reflux ratio is 1-2, and the number of theoretical plates is 55-65;
in the feeding of the ethanol tower, the relative volatility of ethanol and isopropanol is small, the boiling points are close, in order to better utilize heat and reduce the separation difficulty, vacuum rectification is preferably adopted, a vacuum rectification method is adopted, the reflux ratio and the number of theoretical plates can be reduced, the energy consumption is reduced, meanwhile, the vacuum rectification is adopted, the temperature at the bottom of the tower is lower, the thermal coupling of a propulsion reboiler and the top material flow of the low-pressure methanol tower is favorably realized, and the insufficient heat is partially supplemented by steam.
According to a preferred embodiment provided by the second aspect, the purity of methanol produced by the high-pressure methanol column is 99.5 to 99.9wt%.
According to a preferred embodiment provided by the second aspect, the purity of the methanol extracted by the low-pressure methanol tower is 99.5-99.9wt%.
According to a preferred embodiment provided by the second aspect, the ethanol column produces ethanol with a purity of 99.5 to 99.75wt%.
According to a preferred embodiment provided by the second aspect, an overhead separated product comprising a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope output from an overhead discharge port of the deesterification tower is condensed and separated, the obtained uncondensed gas is sent to a fuel gas pipe network and/or a flare system, part of the obtained condensed liquid is refluxed to the deesterification tower, and the rest is used for methyl acetate hydrogenation reaction.
In a third aspect, the present invention also provides a methyl acetate hydrogenation product thermal coupling separation method, which is performed by using the above methyl acetate hydrogenation product thermal coupling separation device, and comprises:
the methyl acetate hydrogenation product enters a deesterification tower through a middle feed inlet of the deesterification tower for rectification, a tower top separated substance containing a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope is output from a discharge outlet at the top of the deesterification tower, and a tower bottom separated substance containing methanol, ethanol and C3+ alcohol is output from a discharge outlet at the bottom of the deesterification tower;
the tower bottom separated substance containing methanol, ethanol and C3+ alcohol and output from a bottom discharge hole of the deesterification tower enters the high-pressure methanol tower through a middle feed hole of the high-pressure methanol tower to be rectified, a methanol product is output from a top discharge hole of the high-pressure methanol tower, and the tower bottom separated substance containing methanol, ethanol and C3+ alcohol is output from a bottom discharge hole of the high-pressure methanol tower; the tower bottom separated substance which is output from a bottom discharge hole of the high-pressure methanol tower and contains methanol, ethanol and C3+ alcohol enters the low-pressure methanol tower through a middle feed hole of the low-pressure methanol tower to be rectified, a methanol product is output from a top discharge hole of the low-pressure methanol tower, and the tower bottom separated substance which contains ethanol and C3+ alcohol is output from a bottom discharge hole of the low-pressure methanol tower;
feeding the tower bottom isolate containing ethanol and C3+ alcohol, which is output from a bottom discharge hole of the low-pressure methanol tower, into the ethanol tower through a middle feed hole of the ethanol tower for rectification, outputting an ethanol product from a top discharge hole of the ethanol tower, and outputting a C3+ alcohol product from a bottom discharge hole of the ethanol tower;
wherein, the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation heat exchange;
in this case, the high-pressure methanol column and the low-pressure methanol column are connected in series.
In the methyl acetate hydrogenation product thermal coupling separation method provided by the third aspect, part of the streams output from the top discharge ports of the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower need to flow back to the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower through the top reflux ports.
According to a preferred embodiment provided by the third aspect, the heat source of the reboiler of the low pressure methanol column is a stream in the top outlet of the high pressure methanol column.
According to a preferred embodiment provided by the third aspect, wherein the heat source of the reboiler of the deesterification column is steam.
According to a preferred embodiment provided by the third aspect, the heat source of the reboiler of the high pressure methanol column is steam.
According to the third aspect, the preferable embodiment is provided, wherein the stream in the top discharge port of the low-pressure methanol tower enters the reboiler of the ethanol tower in a gas phase for condensation heat exchange;
further, the heat source of the reboiler of the ethanol tower is material flow and steam in a discharge hole at the top of the low-pressure methanol tower;
furthermore, the proportion of the reboiler of the ethanol tower adopting steam as a heat source is not higher than 25% of the total heat load of the reboiler of the ethanol tower.
According to a preferred embodiment provided by the third aspect, the temperature difference between the top of the high pressure methanol tower and the bottom of the low pressure methanol tower is 10-15 ℃.
According to a preferred embodiment provided by the third aspect, the temperature difference between the top of the low-pressure methanol column and the bottom of the ethanol column is 10-15 ℃.
According to a preferred embodiment provided by the third aspect, wherein the rectification performed in the deesterification column is vacuum rectification;
further, the operating pressure of the deesterification tower is 100-400kPa, the reflux ratio is 8-12, and the number of theoretical plates is 60-90;
further, the operating pressure of the deesterification tower is 120-200kPa, the reflux ratio is 9-11, and the theoretical plate number is 70-80.
According to a preferred embodiment provided by the third aspect, the rectification performed in the high-pressure methanol column is pressure rectification;
further, the operating pressure of the high-pressure methanol tower is 300-700kPa, the reflux ratio is 4-6, and the number of theoretical plates is 60-90; in one embodiment, the high pressure methanol column has an operating pressure of 300 to 700kPa, a reflux ratio of 4 to 6, and a theoretical plate number of 60 to 80;
furthermore, the operating pressure of the high-pressure methanol tower is 450-600kPa, the reflux ratio is 4-5, and the number of theoretical plates is 70-80.
According to a preferred embodiment provided by the third aspect, the rectification performed in the low-pressure methanol column is pressure rectification;
further, the operating pressure of the low-pressure methanol tower is 100-250kPa, the reflux ratio is 5-8, and the number of theoretical plates is 100-140;
furthermore, the operating pressure of the low-pressure methanol tower is 130-180kPa, the reflux ratio is 6-7, and the number of theoretical plates is 110-130;
according to a preferred embodiment provided by the third aspect, the rectification performed in the ethanol column is a slight positive pressure rectification;
further, the operating pressure of the ethanol tower is 5-100kPa, the reflux ratio is 0.8-2.5, and the number of theoretical plates is 50-70;
furthermore, the operating pressure of the ethanol tower is 10-40kPa, the reflux ratio is 1-2, and the number of theoretical plates is 55-65;
in the feeding of the ethanol tower, the relative volatility of ethanol and isopropanol is small, the boiling points are close, in order to better utilize heat and reduce the separation difficulty, vacuum rectification is preferably adopted, a vacuum rectification method is adopted, the reflux ratio and the number of theoretical plates can be reduced, the energy consumption is reduced, meanwhile, the vacuum rectification is adopted, the temperature at the bottom of the tower is lower, the thermal coupling of a propulsion reboiler and the top material flow of the low-pressure methanol tower is favorably realized, and the insufficient heat is partially supplemented by steam.
According to a preferred embodiment provided by the third aspect, the purity of methanol produced by the high pressure methanol column is 99.5-99.9wt%.
According to a preferred embodiment provided by the third aspect, the purity of the methanol extracted by the low-pressure methanol tower is 99.5-99.9wt%.
According to a preferred embodiment provided by the third aspect, the ethanol column produces ethanol with a purity of 99.5 to 99.75wt%.
According to the third aspect, a preferable embodiment is provided, wherein the overhead separation material comprising the methanol/methyl acetate azeotrope and the methanol/ethyl acetate azeotrope output from the top discharge port of the deesterification tower is condensed and separated, the obtained uncondensed gas is sent to a fuel gas pipe network and/or a torch system, part of the obtained condensed liquid flows back to the deesterification tower, and the rest is used for methyl acetate hydrogenation reaction;
the azeotrope of methyl acetate, ethyl acetate and methanol is directly returned to the methyl acetate hydrogenation reactor (ethyl acetate can be hydrogenated to produce ethanol), and methyl acetate and ethyl acetate products are not separated, so that the process flow is greatly shortened, and the raw material waste is not caused.
The technical scheme provided by the invention utilizes a mode of thermally coupling the high-pressure methanol tower and the low-pressure methanol tower to realize the separation of methanol with low energy consumption and high efficiency, and is matched with the separation action of the deesterification tower and the ethanol tower, so that the device and the method for effectively separating ethanol, methanol and C3-C4 alcohol can be realized while the steam usage amount is reduced. Specifically, the technical scheme provided by the invention is that firstly, an azeotrope of methanol/methyl acetate and methanol/ethyl acetate is separated from the top of the light component removal tower, then methanol, ethanol and C3-C4 alcohol are sequentially separated from a high-pressure methanol tower, a low-pressure methanol tower and an ethanol tower by taking the separation of the methanol and the ethanol as the key point. In the parallel flow (shown in figure 1) of the high-pressure methanol tower and the low-pressure methanol tower, methanol and ethanol are separated from the tower top by a clear division method, and the thermal coupling of the high-pressure methanol tower top material flow and a low reboiler of the low-pressure methanol tower is realized by adjusting the feeding amount of the high-pressure methanol tower and the low-pressure methanol tower; in the series flow (as shown in FIG. 2) of high and low pressure methanol towers, the high pressure methanol tower adopts a methanol and ethanol fuzzy partition method, a part of methanol is separated from the tower top, and the other part of methanol enters the low pressure methanol tower along with ethanol; the low-pressure methanol tower adopts a clear division method of methanol and ethanol, the methanol is separated from the tower top, and the high-pressure methanol tower and the low-pressure methanol tower realize the thermal coupling of the high-pressure methanol tower top material flow and a low reboiler of the low-pressure methanol tower by adjusting the high-pressure methanol tower top output quantity; in the ethanol column, separation of ethanol from C3-C4 alcohols is achieved.
Drawings
Figure 1 is a schematic diagram of a thermally coupled separation unit for the methyl acetate hydrogenation product provided in example 1.
Figure 2 is a schematic diagram of a thermally coupled separation unit for the methyl acetate hydrogenation product provided in example 2.
Detailed Description
The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.
Example 1:
the embodiment provides a thermally coupled separation device for a methyl acetate hydrogenation product, and the structure of the thermally coupled separation device is shown in figure 1.
The device includes:
a deesterification tower 11, a high pressure methanol tower 12, a low pressure methanol tower 13 and an ethanol tower 14; wherein, the deesterification tower 11, the high-pressure methanol tower 12, the low-pressure methanol tower 13 and the ethanol tower 14 are all provided with a top discharge hole, a top reflux hole, a middle feed hole and a bottom discharge hole, the deesterification tower 11 is provided with a reboiler 111, the high-pressure methanol tower 12 is provided with a reboiler 121, the low-pressure methanol tower 13 is provided with a reboiler 131, and the ethanol tower 14 is provided with a first reboiler 141 and a second reboiler 142;
the bottom discharge port of the deesterification tower 11 is respectively connected with the middle feed port of the high-pressure methanol tower 12 and the middle feed port of the low-pressure methanol tower 13, the bottom discharge port of the high-pressure methanol tower 12 and the bottom discharge port of the low-pressure methanol tower 13 are respectively connected with the middle feed port of the ethanol tower 14, and at the moment, the high-pressure methanol tower 12 and the low-pressure methanol tower 13 are connected in parallel;
a discharge port at the top of the high-pressure methanol tower 12 is connected with a hot side inlet of a reboiler 131 of the low-pressure methanol tower 13, and a hot side outlet of the reboiler 131 of the low-pressure methanol tower 13 is respectively connected with a top reflux port of the high-pressure methanol tower 12 and a methanol product output pipeline;
a discharge port at the top of the low-pressure methanol tower 13 is connected with a hot-side inlet of a first reboiler 141 of the ethanol tower 14, and a hot-side outlet of the first reboiler 141 of the ethanol tower 14 is respectively connected with a reflux port at the top of the low-pressure methanol tower 13 and a methanol product output pipeline;
wherein, the middle feed inlet of the deesterification tower 11 is used for supplying methyl acetate hydrogenation products to the deesterification tower 11; the top reflux port of the deesterification tower 11 is used for refluxing to the deesterification tower 11, and reflux liquid comes from a condensate flow of gas output from the top discharge port of the deesterification tower 11; the top reflux port of the ethanol tower 14 is used for refluxing to the ethanol tower 14, and reflux liquid is a condensate flow of gas output from the top discharge port of the ethanol tower;
wherein, the deesterification tower 11 is used for separating methanol/methyl acetate azeotrope and methanol/ethyl acetate azeotrope in the methyl acetate hydrogenation product; the high pressure methanol tower 12 is used for separating methanol; the low-pressure methanol tower 13 is used for separating methanol; the ethanol column 14 is used for separating ethanol;
a discharge port at the top of the ethanol tower 14 is used for outputting ethanol outwards; a discharge port at the bottom of the ethanol tower 14 is used for outputting C3+ alcohol (mainly C3-C4 alcohol) outwards; a discharge port at the top of the low-pressure methanol tower 13 is used for outputting methanol outwards;
further, the deesterification column 11 can be used for performing a micro-positive pressure rectification; still further, the deesterification column 11 can be used to perform rectification at pressures of 100-400 kPa; still further, the deesterification column 11 can be used to perform a rectification at a pressure of 120-200 kPa;
further, the high pressure methanol column 12 can be used for pressure rectification; further, the high pressure methanol column 12 can be used to perform rectification at pressures of 300-700 kPa; still further, the high pressure methanol column 12 can be used to perform rectification at pressures of 450-600 kPa;
further, the low-pressure methanol column 13 can be used for performing micro-positive pressure rectification; further, the low pressure methanol column 13 can be used for rectification at a pressure of 100 to 250 kPa; still further, the low pressure methanol column 13 can be used to perform rectification at a pressure of 130-180 kPa;
further, the ethanol column 14 can be used to perform vacuum rectification; still further, the ethanol column 14 can be used to perform rectification at pressures of 5-100 kPa; still further, the ethanol column 14 can be used to perform rectification at pressures of 10-40 kPa.
Further, the hot side inlet of the second reboiler 142 of the ethanol column 14 is connected to a steam supply.
Further, a hot side inlet of the reboiler 111 of the deesterification column 11 is connected to a steam supply source.
Further, the hot side inlet of the reboiler 121 of the high pressure methanol column 12 is connected to a steam supply.
Further, the device is provided with a depolyzation tower depolyzer 15, and the depolyzation tower depolyzer 15 is respectively connected with a top discharge port of the depolyzation tower 11 and a top reflux port of the depolyzation tower 11.
Further, the device is provided with an ethanol tower condenser 16, and the ethanol tower condenser 16 is respectively connected with a top discharge port of the ethanol tower 14 and a top reflux port of the ethanol tower 14.
Further, a pump is arranged on a connecting pipeline between a hot side outlet of the reboiler 131 of the low pressure methanol tower 13 and a top reflux port of the high pressure methanol tower 12.
Further, a pump is arranged on a connecting pipeline between the top discharge port of the low-pressure methanol tower 13 and the hot-side inlet of the first reboiler 141 of the ethanol tower 14.
Example 2:
this example provides a thermally coupled separation device for a methyl acetate hydrogenation product, the structure of which is shown in fig. 2.
The device includes:
a deesterification tower 21, a high-pressure methanol tower 22, a low-pressure methanol tower 23 and an ethanol tower 24; wherein, the deesterification tower 21, the high-pressure methanol tower 22, the low-pressure methanol tower 23 and the ethanol tower 24 are all provided with a top discharge hole, a top reflux hole, a middle feed hole and a bottom discharge hole, the deesterification tower 21 is provided with a reboiler 211, the high-pressure methanol tower 22 is provided with a reboiler 221, the low-pressure methanol tower 23 is provided with a reboiler 231, and the ethanol tower 24 is provided with a first reboiler 241 and a second reboiler 242;
the bottom discharge port of the deesterification tower 21 is connected with the middle feed port of the high-pressure methanol tower 22, the bottom discharge port of the high-pressure methanol tower 22 is connected with the middle feed port of the low-pressure methanol tower 23, the bottom discharge port of the low-pressure methanol tower 23 is connected with the middle feed port of the ethanol tower 24, and at the moment, the high-pressure methanol tower 22 and the low-pressure methanol tower 23 are connected in series;
a discharge port at the top of the high-pressure methanol tower 22 is connected with a hot side inlet of a reboiler 231 of the low-pressure methanol tower 23, and a hot side outlet of the reboiler 231 of the low-pressure methanol tower 23 is respectively connected with a top reflux port of the high-pressure methanol tower 22 and a methanol product output pipeline;
a discharge port at the top of the low-pressure methanol tower 23 is connected with a hot-side inlet of a first reboiler 241 of the ethanol tower 24, and a hot-side outlet of the first reboiler 241 of the ethanol tower 24 is respectively connected with a reflux port at the top of the low-pressure methanol tower 23 and a methanol product output pipeline;
wherein, the middle feed inlet of the deesterification tower 21 is used for supplying methyl acetate hydrogenation products to the deesterification tower 21; the top reflux port of the deesterification tower 21 is used for refluxing to the deesterification tower 21, and reflux liquid comes from a condensate flow of gas output from the top discharge port of the deesterification tower 21; the top reflux port of the ethanol tower 24 is used for refluxing to the ethanol tower 24, and reflux liquid is a condensate flow of gas output from the top discharge port of the ethanol tower;
wherein, the deesterification tower 21 is used for separating methanol/methyl acetate azeotrope and methanol/ethyl acetate azeotrope in the methyl acetate hydrogenation product; the high pressure methanol column 22 is used to separate methanol; the low-pressure methanol tower 23 is used for separating methanol; the ethanol tower 24 is used for separating ethanol;
a discharge hole at the top of the ethanol tower 24 is used for outputting ethanol outwards; a discharge port at the bottom of the ethanol tower 24 is used for outputting C3+ alcohol (mainly C3-C4 alcohol);
further, the deesterification column 21 can be used to perform a micro positive pressure rectification; further, the deesterification column 21 can be used to perform rectification at pressures of 100 to 400 kPa; still further, the deesterification column 21 can be used to perform a rectification at a pressure of 220 to 200 kPa;
further, the high pressure methanol column 22 can be used for pressure rectification; still further, the high pressure methanol column 22 can be used to perform rectification at pressures of 300-700 kPa; still further, the high pressure methanol column 22 can be used to perform rectification at pressures of 450-600 kPa;
further, the low pressure methanol column 23 can be used for performing micro positive pressure rectification; further, the low-pressure methanol column 23 can be used for rectification at a pressure of 100 to 250 kPa; still further, the low pressure methanol column 23 can be used to perform rectification at a pressure of 230-180 kPa;
further, the ethanol column 24 can be used to perform vacuum rectification; further, the ethanol column 24 can be used to perform rectification at pressures of 5-100 kPa; still further, the ethanol column 24 can be used to perform rectification at pressures of 10-40 kPa.
Further, the hot side inlet of the second reboiler 242 of the ethanol column 24 is connected to a steam supply.
Further, a hot side inlet of the reboiler 211 of the deesterification column 21 is connected to a steam supply source.
Further, the hot side inlet of the reboiler 221 of the high pressure methanol column 22 is connected to a steam supply source.
Further, the device is provided with a depolyester tower depolyer 25, and the depolyester tower depolyer 25 is respectively connected with a top discharge port of the depolyester tower 21 and a top reflux port of the depolyester tower 21.
Further, the device is provided with an ethanol tower condenser 26, and the ethanol tower condenser 26 is respectively connected with a top discharge port of the ethanol tower 24 and a top reflux port of the ethanol tower 24.
Furthermore, a pump is arranged on a connecting pipeline between a hot side outlet of the reboiler 231 of the low-pressure methanol tower 23 and a top reflux port of the high-pressure methanol tower 22.
Further, a pump is arranged on a connecting pipeline between the top discharge port of the low-pressure methanol tower 23 and the hot side inlet of the first reboiler 241 of the ethanol tower 24.
Example 3:
this example provides a process for thermally coupling separation of a methyl acetate hydrogenated product using a thermally coupled separation unit for a methyl acetate hydrogenated product as described in example 1, having a processing capacity of 25 ten thousand tons/year coal-based ethanol.
The methyl acetate hydrogenation product treated by the method mainly contains dimethyl ether, unreacted methyl acetate, methanol, ethyl acetate, ethanol, isopropanol, n-propanol, sec-butanol and the like.
The method comprises the following steps:
the methyl acetate hydrogenation product enters the deesterification tower through a middle feed inlet of the deesterification tower for micro-positive pressure rectification, the pressure is 0.02-0.04MPa (G), the theoretical plate number is 75, and the reflux ratio is 9.5. Outputting a tower top separated substance containing methanol/methyl acetate azeotrope and methanol/ethyl acetate azeotrope from a top discharge hole of the deesterification tower, and outputting a tower bottom separated substance containing methanol, ethanol and C3+ alcohol from a bottom discharge hole of the deesterification tower;
and part of the tower bottom separated material containing methanol, ethanol and C3+ alcohol and output from a bottom discharge hole of the deesterification tower enters the high-pressure methanol tower through a middle feed inlet of the high-pressure methanol tower for pressure rectification, wherein the pressure is 0.4MPa (G), the theoretical plate number is 90, and the reflux ratio is 4.2. The other part enters the low-pressure methanol tower through a middle feed inlet of the low-pressure methanol tower for micro-positive pressure rectification, the pressure is 0.06MPa (G), the number of theoretical plates is 90, and the reflux ratio is 3.3. The methanol product is output from the top discharge ports of the high-pressure methanol tower and the low-pressure methanol tower, and the purity is 99.95wt%. Outputting tower bottom separated substances containing ethanol and C3+ alcohol from bottom discharge ports of the high-pressure methanol tower and the low-pressure methanol tower;
the tower bottom separated substances which are output from the bottom discharge ports of the high-pressure methanol tower and the low-pressure methanol tower and contain ethanol and C3+ alcohol enter the ethanol tower through the middle feed port of the ethanol tower to be subjected to vacuum rectification, wherein the pressure is 20kPa (A), the number of theoretical plates is 60, and the reflux ratio is 1.3. The ethanol product is output from a discharge hole at the top of the ethanol tower, and the purity is 99.75wt%. Outputting a C3+ alcohol product from a discharge hole at the bottom of the ethanol tower;
wherein, the heat source of the reboiler of the deesterification tower is steam; the heat source of a reboiler of the high-pressure methanol tower is steam; the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation heat exchange, and the heat source of the reboiler of the low-pressure methanol tower is the material flow in the top discharge hole of the high-pressure methanol tower; the material flow in the discharge hole at the top of the low-pressure methanol tower enters a reboiler of the ethanol tower in a gas phase mode for condensation heat exchange, the heat source of the reboiler of the ethanol tower is the material flow and steam in the discharge hole at the top of the low-pressure methanol tower, and the proportion of the steam adopted by the reboiler of the ethanol tower as the heat source is about 25 percent of the total heat load of the reboiler of the ethanol tower;
wherein the temperature difference between the top of the high-pressure methanol tower and the bottom of the low-pressure methanol tower is 10 ℃; the temperature difference between the top of the low-pressure methanol tower and the bottom of the ethanol tower is 10 ℃.
In the method, the overhead isolate containing the methanol/methyl acetate azeotrope and the methanol/ethyl acetate azeotrope output from the discharge port at the top of the deesterification tower is condensed and separated, the obtained noncondensable gas is sent to a fuel gas pipe network and/or a torch system, part of the obtained condensate flows back to the deesterification tower, and the rest part is used for methyl acetate hydrogenation reaction.
In the separation process provided in this example, the steam consumption was reduced to 1.94t/t ethanol.
Example 4:
this example provides a methyl acetate hydrogenation product thermal coupling separation process, which was carried out using the methyl acetate hydrogenation product thermal coupling separation apparatus described in example 2, and which had a processing capacity of 60 ten thousand tons/year coal-based ethanol.
The methyl acetate hydrogenation product treated by the method mainly contains dimethyl ether, unreacted methyl acetate, methanol, ethyl acetate, ethanol, isopropanol, n-propanol, sec-butanol and the like.
The method comprises the following steps:
the methyl acetate hydrogenation product enters the deesterification tower through a middle feed inlet of the deesterification tower for micro-positive pressure rectification, the pressure is 0.02-0.04MPa (G), the theoretical plate number is 75, and the reflux ratio is 9.5. Outputting a tower top separated substance containing methanol/methyl acetate azeotrope and methanol/ethyl acetate azeotrope from a top discharge hole of the deesterification tower, and outputting a tower bottom separated substance containing methanol, ethanol and C3+ alcohol from a bottom discharge hole of the deesterification tower;
the tower bottom separated substance which is output from a discharge hole at the bottom of the deesterification tower and contains methanol, ethanol and C3+ alcohol enters the high-pressure methanol tower through a middle feed inlet of the high-pressure methanol tower for pressure rectification, the pressure is 0.4MPa (G), the theoretical plate number is 75, and the reflux ratio is 4.2. The high-pressure methanol tower is divided by fuzzy separation, a part of methanol with the purity of 99.95wt% is separated from the tower top, a discharge hole at the tower bottom outputs a tower bottom separated substance of the methanol, the ethanol and the C3+ alcohol, and the tower bottom separated substance enters the low-pressure methanol tower through a middle feed inlet of the low-pressure methanol tower to be rectified under the micro-positive pressure, wherein the pressure is 0.08MPa (G), the theoretical plate number is 120, and the reflux ratio is 7. The low-pressure methanol tower realizes the clear division of methanol and ethanol, the methanol with the purity of 99.95wt% is separated out from the tower top, and the tower bottom separated material of ethanol and C3+ alcohol is output from a discharge port at the tower bottom; the ratio of methanol separated from the top of the high pressure methanol column to methanol separated from the low pressure methanol column is about 0.6.
And tower bottom separated substances which are output from a bottom discharge hole of the low-pressure methanol tower and contain ethanol and C3+ alcohol enter the ethanol tower through a middle feed inlet of the ethanol tower to be subjected to vacuum rectification, wherein the pressure is 20kPa (A), the number of theoretical plates is 60, and the reflux ratio is 1.3. The ethanol product is output from a discharge port at the top of the ethanol tower, and the purity is 99.75wt%. Outputting a C3+ alcohol product from a discharge hole at the bottom of the ethanol tower;
wherein the heat source of the reboiler of the deesterification tower is steam; the heat source of a reboiler of the high-pressure methanol tower is steam; the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation and heat exchange, and the heat source of the reboiler of the low-pressure methanol tower is the material flow in the top discharge hole of the high-pressure methanol tower; feeding the material flow in a discharge port at the top of the low-pressure methanol tower into a reboiler of the ethanol tower in a gas phase mode for condensation heat exchange; the heat source of the reboiler of the ethanol tower is material flow and steam in a discharge hole at the top of the low-pressure methanol tower, and the proportion of the steam adopted by the reboiler of the ethanol tower as the heat source is about 8 percent of the total heat load of the reboiler of the ethanol tower;
wherein the temperature difference between the top of the high-pressure methanol tower and the bottom of the low-pressure methanol tower is 15 ℃; the temperature difference between the top of the low-pressure methanol tower and the bottom of the ethanol tower is 13 ℃.
In the method, the overhead isolate containing the methanol/methyl acetate azeotrope and the methanol/ethyl acetate azeotrope output from the discharge port at the top of the deesterification tower is condensed and separated, the obtained noncondensable gas is sent to a fuel gas pipe network and/or a torch system, part of the obtained condensate flows back to the deesterification tower, and the rest part is used for methyl acetate hydrogenation reaction.
In the separation process provided in this example, the steam consumption was reduced to 2.13t/t ethanol.
The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. A thermally coupled separation unit for a methyl acetate hydrogenation product, wherein the unit comprises: a deesterification tower, a high-pressure methanol tower, a low-pressure methanol tower and an ethanol tower; wherein:
the deesterification tower, the high-pressure methanol tower, the low-pressure methanol tower and the ethanol tower are all provided with a top discharge hole, a top reflux hole, a middle feed hole, a bottom discharge hole and a reboiler;
the bottom discharge port of the deesterification tower is connected with the middle feed inlet of the high-pressure methanol tower, the bottom discharge port of the high-pressure methanol tower is connected with the middle feed inlet of the low-pressure methanol tower, the bottom discharge port of the low-pressure methanol tower is connected with the middle feed inlet of the ethanol tower, and the high-pressure methanol tower is connected with the low-pressure methanol tower in series; or the bottom discharge port of the deesterification tower is respectively connected with the middle feed port of the high-pressure methanol tower and the middle feed port of the low-pressure methanol tower, the bottom discharge port of the high-pressure methanol tower and the bottom discharge port of the low-pressure methanol tower are respectively connected with the middle feed port of the ethanol tower, and the high-pressure methanol tower and the low-pressure methanol tower are connected in parallel;
the top discharge port of the high-pressure methanol tower is connected with the hot side inlet of the reboiler of the low-pressure methanol tower, and the hot side outlet of the reboiler of the low-pressure methanol tower is connected with the top reflux port of the high-pressure methanol tower.
2. The apparatus of claim 1, wherein,
a discharge port at the top of the low-pressure methanol tower is connected with a hot side inlet of a reboiler of the ethanol tower, and a hot side outlet of the reboiler of the ethanol tower is connected with a top reflux port of the low-pressure methanol tower; preferably, the reboiler of the ethanol column comprises a first reboiler and a second reboiler; and a discharge port at the top of the low-pressure methanol tower is connected with a hot side inlet of a first reboiler of the ethanol tower, and a hot side outlet of the first reboiler of the ethanol tower is connected with a reflux port at the top of the low-pressure methanol tower.
3. The apparatus of claim 1, wherein,
the device is further provided with a depolyzation tower depolyzer which is respectively connected with a top discharge hole of the depolyzation tower and a top reflux hole of the depolyzation tower;
the device is further provided with an ethanol tower condenser, and the ethanol tower condenser is respectively connected with a top discharge hole of the ethanol tower and a top reflux hole of the ethanol tower.
4. The apparatus of any one of claims 1-3,
when the high-pressure methanol tower and the low-pressure methanol tower are connected in parallel, the deesterification tower can be used for rectifying under the pressure of 100-400kPa, the reflux ratio of 8-12 and the theoretical plate number of 60-90; the high pressure methanol column can be used for pressure rectification; further, the high pressure methanol column can be used for rectification under 300-700kPa pressure, 4-6 reflux ratio and 75-100 theoretical plates; the low-pressure methanol tower can be used for micro-positive pressure rectification; further, the low pressure methanol column can be used for rectification at 100-250kPa pressure, 3-5 reflux ratio, 70-90 theoretical plate number; the ethanol column can be used for vacuum rectification; further, the ethanol column can be used for rectification at a pressure of 5-100kPa, a reflux ratio of 0.8-2.5, and a theoretical plate number of 50-70;
preferably, the deesterification column is capable of being used to carry out a rectification at a pressure of 120 to 200kPa, a reflux ratio of 9 to 11, and a theoretical plate number of 70 to 80; the high-pressure methanol tower can be used for rectifying under the pressure of 450-600kPa, the reflux ratio of 4-5 and the number of theoretical plates of 80-90; the low-pressure methanol tower can be used for rectifying under the pressure of 130-180kPa, the reflux ratio of 3-4 and the theoretical plate number of 80-90; the ethanol tower can be used for rectifying under the pressure of 10-40kPa, the reflux ratio of 1-2 and the number of 55-65 theoretical plates;
when the high-pressure methanol tower and the low-pressure methanol tower are connected in series, the deesterification tower can be used for rectifying under the pressure of 100-400kPa, the reflux ratio of 8-12 and the theoretical plate number of 60-90; the high pressure methanol column can be used for pressure rectification; the high-pressure methanol tower can be used for carrying out 300-700kPa pressure, 4-6 reflux ratio and 60-90 theoretical plate number; the low-pressure methanol tower can be used for rectifying under the pressure of 100-250kPa, the reflux ratio of 5-8 and the number of theoretical plates of 100-140; the ethanol tower can be used for rectifying under the pressure of 5-100kPa, the reflux ratio of 0.8-2.5 and the number of theoretical plates of 50-70;
preferably, the deesterification column is capable of being used to carry out a rectification at a pressure of 120 to 200kPa, a reflux ratio of 9 to 11, and a theoretical plate number of 70 to 80; the high-pressure methanol tower can be used for rectifying under the pressure of 450-600kPa, the reflux ratio of 4-5 and the number of theoretical plates of 70-80; the low-pressure methanol tower can be used for rectifying under the pressure of 130-180kPa, the reflux ratio of 6-7 and the theoretical plate number of 110-130; the ethanol column can be used for rectification under the pressure of 10-40kPa, the reflux ratio of 1-2 and the number of theoretical plates of 55-65.
5. A process for thermally coupling separation of a methyl acetate hydrogenation product, the process being carried out using a thermally coupled separation device for a methyl acetate hydrogenation product as claimed in any one of claims 1 to 4, the process comprising:
the methyl acetate hydrogenation product enters a deesterification tower through a middle feed inlet of the deesterification tower for rectification, a tower top separated substance containing a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope is output from a discharge outlet at the top of the deesterification tower, and a tower bottom separated substance containing methanol, ethanol and C3+ alcohol is output from a discharge outlet at the bottom of the deesterification tower;
one part of the tower bottom separated materials which are output from a bottom discharge hole of the deesterification tower and contain methanol, ethanol and C3+ alcohol enters the high-pressure methanol tower through a middle feed hole of the high-pressure methanol tower to be rectified, the other part of the tower bottom separated materials enters the low-pressure methanol tower through a middle feed hole of the low-pressure methanol tower to be rectified, methanol products are output from top discharge holes of the high-pressure methanol tower and the low-pressure methanol tower, and the tower bottom separated materials which contain the ethanol and the C3+ alcohol are output from bottom discharge holes of the high-pressure methanol tower and the low-pressure methanol tower; tower bottom isolates containing ethanol and C3+ alcohol and output from the bottom discharge ports of the high-pressure methanol tower and the low-pressure methanol tower enter the ethanol tower through the middle feed port of the ethanol tower to be rectified, ethanol products are output from the top discharge port of the ethanol tower, and C3+ alcohol products are output from the bottom discharge port of the ethanol tower;
wherein, the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation heat exchange.
6. The method of claim 5, wherein,
the heat source of the reboiler of the low-pressure methanol tower is material flow in a discharge hole at the top of the high-pressure methanol tower;
the heat source of a reboiler of the deesterification tower is steam;
the heat source of a reboiler of the high-pressure methanol tower is steam;
feeding the material flow in a discharge port at the top of the low-pressure methanol tower into a reboiler of the ethanol tower in a gas phase mode for condensation heat exchange; preferably, the heat source of the reboiler of the ethanol tower is the material flow and the steam in the top discharge hole of the low-pressure methanol tower; more preferably, the proportion of the reboiler of the ethanol column that uses steam as a heat source is not more than 25% of the total heat duty of the reboiler of the ethanol column.
7. The method of claim 5, wherein,
the temperature difference between the top of the high-pressure methanol tower and the bottom of the low-pressure methanol tower is 10-15 ℃;
the temperature difference between the top of the low-pressure methanol tower and the bottom of the ethanol tower is 10-15 ℃;
the operating pressure of the deesterification tower is 100-400kPa, the reflux ratio is 8-12, and the number of theoretical plates is 60-90; preferably, the operating pressure of the deesterification tower is 120-200kPa, the reflux ratio is 9-11, and the theoretical plate number is 70-80;
the operating pressure of the high-pressure methanol tower is 300-700kPa, the reflux ratio is 4-6, and the number of theoretical plates is 75-100; preferably, the operating pressure of the high-pressure methanol tower is 450-600kPa, the reflux ratio is 4-5, and the number of theoretical plates is 80-90;
the operating pressure of the low-pressure methanol tower is 100-250kPa, the reflux ratio is 3-5, and the number of theoretical plates is 70-90; preferably, the operating pressure of the low-pressure methanol tower is 130-180kPa, the reflux ratio is 3-4, and the number of theoretical plates is 80-90;
the operating pressure of the ethanol tower is 5-100kPa, the reflux ratio is 0.8-2.5, and the number of theoretical plates is 50-70; preferably, the operating pressure of the ethanol tower is 10-40kPa, the reflux ratio is 1-2, and the theoretical plate number is 55-65.
8. A methyl acetate hydrogenation product thermal coupling separation method, which is carried out by using the methyl acetate hydrogenation product thermal coupling separation device of any one of claims 1 to 4, and which comprises:
the methyl acetate hydrogenation product enters a deesterification tower through a middle feed inlet of the deesterification tower for rectification, a tower top separated substance containing a methanol/methyl acetate azeotrope and a methanol/ethyl acetate azeotrope is output from a discharge outlet at the top of the deesterification tower, and a tower bottom separated substance containing methanol, ethanol and C3+ alcohol is output from a discharge outlet at the bottom of the deesterification tower;
the method comprises the following steps that (1) tower bottom separated matters which are output from a bottom discharge hole of a deesterification tower and contain methanol, ethanol and C3+ alcohol enter a high-pressure methanol tower through a middle feed hole of the high-pressure methanol tower to be rectified, a methanol product is output from a top discharge hole of the high-pressure methanol tower, and tower bottom separated matters which contain the methanol, the ethanol and the C3+ alcohol are output from a bottom discharge hole of the high-pressure methanol tower; the tower bottom separated substance which is output from a bottom discharge hole of the high-pressure methanol tower and contains methanol, ethanol and C3+ alcohol enters the low-pressure methanol tower through a middle feed hole of the low-pressure methanol tower to be rectified, a methanol product is output from a top discharge hole of the low-pressure methanol tower, and the tower bottom separated substance which contains ethanol and C3+ alcohol is output from a bottom discharge hole of the low-pressure methanol tower;
feeding the tower bottom isolate containing ethanol and C3+ alcohol, which is output from a bottom discharge hole of the low-pressure methanol tower, into the ethanol tower through a middle feed hole of the ethanol tower for rectification, outputting an ethanol product from a top discharge hole of the ethanol tower, and outputting a C3+ alcohol product from a bottom discharge hole of the ethanol tower;
wherein, the material flow in the top discharge hole of the high-pressure methanol tower enters a reboiler of the low-pressure methanol tower in a gas phase mode for condensation heat exchange.
9. The method of claim 8, wherein,
the heat source of the reboiler of the low-pressure methanol tower is material flow in a discharge hole at the top of the high-pressure methanol tower;
the heat source of a reboiler of the deesterification tower is steam;
the heat source of a reboiler of the high-pressure methanol tower is steam;
feeding the material flow in a discharge port at the top of the low-pressure methanol tower into a reboiler of the ethanol tower in a gas phase mode for condensation heat exchange; preferably, the heat source of the reboiler of the ethanol tower is the material flow and the steam in the top discharge hole of the low-pressure methanol tower; more preferably, the proportion of the reboiler of the ethanol column using steam as the heat source is not more than 25% of the total heat duty of the reboiler of the ethanol column.
10. The method of claim 8, wherein,
the temperature difference between the top of the high-pressure methanol tower and the bottom of the low-pressure methanol tower is 10-15 ℃;
the temperature difference between the top of the low-pressure methanol tower and the bottom of the ethanol tower is 10-15 ℃;
the operating pressure of the deesterification tower is 100-400kPa, the reflux ratio is 8-12, and the number of theoretical plates is 60-90; preferably, the operating pressure of the deesterification tower is 120-200kPa, the reflux ratio is 9-11, and the number of theoretical plates is 70-80;
the operating pressure of the high-pressure methanol tower is 300-700kPa, the reflux ratio is 4-6, and the number of theoretical plates is 60-90; preferably, the operating pressure of the high-pressure methanol tower is 450-600kPa, the reflux ratio is 4-5, and the number of theoretical plates is 70-80;
the operating pressure of the low-pressure methanol tower is 100-250kPa, the reflux ratio is 5-8, and the number of theoretical plates is 100-140; preferably, the operating pressure of the low-pressure methanol tower is 130-180kPa, the reflux ratio is 6-7, and the theoretical plate number is 110-130;
the operating pressure of the ethanol tower is 5-100kPa, the reflux ratio is 0.8-2.5, and the number of theoretical plates is 50-70; preferably, the operating pressure of the ethanol tower is 10-40kPa, the reflux ratio is 1-2, and the theoretical plate number is 55-65.
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