CN218553168U - Device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupled rectification - Google Patents
Device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupled rectification Download PDFInfo
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Abstract
The utility model discloses a device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupling rectification, which comprises a reaction rectifying tower, a second heat exchanger, a third heat exchanger, a fifth heat exchanger, a membrane separator, a steam jet vacuum system, a feed pump, an atmospheric tower and a storage tank; the top of the reaction rectifying tower is sequentially communicated with the third heat exchanger and the membrane separator, an outlet at the interception side of the membrane separator is communicated with an inlet of a feed pump, an outlet of the feed pump is communicated with the middle part of the normal pressure tower through a pipeline, and the top of the normal pressure tower is sequentially communicated with the fifth heat exchanger and an inlet at the interception side of the membrane separator through pipelines; the outlet of the permeation side of the membrane separator is communicated with the suction port of the steam jet vacuum system through a pipeline, and the discharge port of the steam jet vacuum system is communicated with the second heat exchanger and the middle lower part of the reaction rectifying tower through pipelines; the storage tank is communicated with the second heat exchanger through a pipeline. The utility model discloses the device whole operation does not need middling pressure steam, and pressurization operating condition cancels, and the running cost reduces by a wide margin.
Description
Technical Field
The utility model relates to a rectification separation technical field especially relates to a device of separation methyl alcohol and dimethyl carbonate azeotrope of membrane separation coupling rectification.
Background
Dimethyl carbonate (DMC), a chemical raw material with low toxicity, excellent environmental protection performance and wide application, is an important organic synthesis intermediate, contains functional groups such as carbonyl, methyl, methoxy and the like in a molecular structure, has various reaction performances, and has the characteristics of safe and convenient use, less pollution, easy transportation and the like in production. Because of low toxicity, the dimethyl carbonate is a green chemical product with development prospect. The DMC production processes that have been commercialized to date mainly comprise two types: one is methanol oxidative carbonylation route using CuCl as catalyst; another is the methanol transesterification route. Due to thermodynamic equilibrium limitation, no matter which production process is adopted, the final product contains DMC and methanol, and further separation and purification are needed to obtain DMC meeting the standard.
At atmospheric pressure, DMC and CH 3 OH forms a binary azeotrope (DMC: 30%, CH) 3 OH:70 percent at a temperature of 63.5 ℃), and high-purity DMC is difficult to obtain by means of atmospheric distillation. The separation of the azeotrope of methanol and dimethyl carbonate is a key link in the industrial production of high-purity dimethyl carbonate, and the separation methods of methanol-DMC mainly comprise a low-temperature crystallization method, an adsorption method, an extractive distillation method, an azeotropic distillation method and a pressure distillation method, and the above separation methods have great defects and disadvantages, such as high cost, high energy consumption, great operation difficulty, poor safety and the like. The DMC/CH which is the current mainstream 3 The OH separation process comprises pressure swing distillation and extractive distillation: the pressure swing distillation has the advantages of high energy consumption, high equipment requirement and complex control; extractive distillation may introduce an extractant simultaneously with the DMC being obtained, and the extractant is generally environmentally toxic.
At present, the method which is applied in industry is pressure rectification, wherein the pressure rectification utilizes methanol-DMC azeotrope to change the azeotropic composition greatly along with the pressure difference, thereby realizing the separation of the methanol-DMC azeotrope and the DMC by utilizing the pressure difference change. The pressure rectification process system generally comprises a reaction rectification tower, a pressure tower and an atmospheric pressure rectification tower, wherein a methanol-DMC azeotrope extracted from the top of the reaction rectification tower contains about 70% of methanol, the methanol-DMC azeotrope enters the pressure rectification tower under the conveying of a pressure pump, the pressure of the pressure tower is controlled to be 8-12bar, the methanol content of a distillate extracted from the top of the pressure tower is more than 80%, the distillate returns to the reaction rectification tower to realize the circulation of the methanol after exchanging heat with a material in a tower kettle of the reaction rectification tower, a DMC crude product containing DMC more than 99% is extracted from the bottom of the pressure tower, and a product with the purity more than 99.9% is obtained through a DMC refining tower. However, the pressure distillation process needs pressure operation, has high energy consumption cost and high equipment investment cost, and does not meet the green production requirements of energy conservation and emission reduction.
SUMMERY OF THE UTILITY MODEL
The invention aims to solve the problem that the traditional separation method is difficult to separate or can not separate organic mixture solution with near boiling point and constant boiling point, and provides a device for separating methanol and dimethyl carbonate azeotrope, which has the advantages of no need of medium-pressure steam in the integral operation of the device, low energy consumption and greatly reduced operation cost.
In order to realize the purpose of the utility model, the technical scheme of the utility model is as follows:
a device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupling rectification comprises a reaction rectification tower, a second heat exchanger, a third heat exchanger, a fifth heat exchanger, a membrane separator, a steam jet vacuum system, a feed pump, an atmospheric tower and a storage tank;
the top of the reaction rectifying tower is sequentially communicated with the third heat exchanger and the membrane separator through pipelines, an outlet at the interception side of the membrane separator is communicated with an inlet of the feed pump through a pipeline, an outlet of the feed pump is communicated with the middle part of the normal pressure tower through a pipeline, and the top of the normal pressure tower is sequentially communicated with the fifth heat exchanger and an inlet at the interception side of the membrane separator through pipelines; the outlet of the permeation side of the membrane separator is communicated with the suction port of the steam jet vacuum system through a pipeline, and the discharge port of the steam jet vacuum system is sequentially communicated with the second heat exchanger and the middle lower part of the reaction rectifying tower through pipelines;
the storage tank is communicated with the second heat exchanger through a pipeline, and the membrane separator comprises a pervaporation membrane module.
In some embodiments, the vapor jet vacuum system comprises a multi-stage vapor jet pump;
the pervaporation membrane is a molecular sieve membrane, the membrane separator comprises a plurality of stages of molecular sieve membrane groups which are arranged in series, an interception side outlet of the upper stage of molecular sieve membrane group is connected with an interception side inlet of the lower stage of molecular sieve membrane group, and an infiltration side outlet of each stage of molecular sieve membrane group is connected in parallel and is communicated with a suction port of the steam jet vacuum system.
In some embodiments, the steam injection vacuum system comprises a five or six stage steam injection pump in combination;
the membrane separator comprises three-stage molecular sieve membrane groups which are arranged in series, and the molecular sieve membrane is an FAU molecular sieve membrane.
In some embodiments, the apparatus further comprises a propylene glycol finishing column, the bottom of the reactive distillation column in communication with the propylene glycol finishing column via a line.
In some embodiments, the apparatus further comprises a first heat exchanger, the bottom of the reactive distillation column is communicated with the inlet of the first heat exchanger through a pipeline, the outlet of the first heat exchanger is communicated with the reactive distillation column through a pipeline, the first heat exchanger is used for heating propylene glycol extracted from the bottom of the reactive distillation column, the heated propylene glycol circularly enters the reactive distillation column, propylene glycol steam flows back upwards and flows back downwards after being condensed by methanol-DMC mixed liquid in the second heat exchanger, and the two phases of vapor and liquid contact transfer mass, so that the distillation process is continuously carried out.
In some embodiments, the apparatus further comprises a DMC purification tower, wherein the bottom of the atmospheric tower is in communication with the DMC purification tower through a pipeline, and DMC extracted from the atmospheric tower enters the DMC purification tower to be purified to obtain a qualified DMC product.
In some embodiments, the apparatus further comprises a fourth heat exchanger, the bottom of the atmospheric tower is communicated with the inlet of the fourth heat exchanger through a pipeline, the outlet of the fourth heat exchanger is communicated with the atmospheric tower through a pipeline, the fourth heat exchanger is used for reheating part of DMC extracted from the atmospheric tower, heated DMC steam is circulated to the atmospheric tower and is subjected to vapor-liquid two-phase contact mass transfer with methanol-DMC mixed liquid condensed by the fifth heat exchanger, and continuous and stable operation of the rectification process in the atmospheric tower is ensured.
In some embodiments, the first heat exchanger, the second heat exchanger and the fourth heat exchanger are reboilers, the third heat exchanger and the fifth heat exchanger are condensers, and the first heat exchanger and the fourth heat exchanger are both heat exchangers using low-pressure raw steam (water vapor) as a heat exchange working medium; the third heat exchanger and the fifth heat exchanger both adopt circulating cooling water as heat exchange working media; the second heat exchanger adopts medium and low pressure steam mixed by high pressure jet medium steam discharged by a steam jet vacuum system and methanol steam at the permeation side of the membrane component as a heat exchange medium.
In some embodiments, the apparatus further comprises a compressor in line communication with the inlet of the vapor injection vacuum system for pressurizing the product vapor, the pressurized product vapor entering the vapor injection vacuum system as the injection medium.
In some embodiments, the apparatus further comprises a vacuum pump connected to the third heat exchanger, the vacuum pump being configured to pump off exhaust gases generated in the third heat exchanger prior to the start of the reaction;
and the outlet of the fifth heat exchanger is also communicated with the upper part of the atmospheric tower through a pipeline and is used for condensing part of methanol-DMC steam extracted from the top of the atmospheric tower and refluxing condensate into the atmospheric tower.
The beneficial effects of the utility model are that: compare the device of former pressurization rectification technology, the utility model discloses the whole operation of device no longer needs middling pressure steam, and pressurization operating condition cancels, and running cost such as energy consumption reduces by a wide margin. The utility model discloses the improvement of novelty has still been made to the vacuum system among the membrane separation process, introduce and use propylene carbonate or methyl alcohol to spray the steam injection vacuum system of power supply, replace the vacuum pump among the traditional membrane separation, can not only provide the required vacuum of membrane separation, can also mix injection steam and methyl alcohol steam simultaneously, retrieve the latent heat of methyl alcohol steam, the material of steam injection vacuum system discharge port provides the heat for partial propylene glycol feed liquid through the second heat exchanger simultaneously, further carry out the recovery of steam latent heat, reduce the energy consumption.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Wherein:
fig. 1 is a schematic structural diagram of the device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupled rectification.
Fig. 2 is a schematic diagram of the membrane separator in the apparatus of the present invention in a preferred embodiment.
Description of reference numerals:
t-101 reaction rectifying tower
T-102 atmospheric tower
E-101 first heat exchanger
E-102 second heat exchanger
E-103 third heat exchanger
E-104 fourth heat exchanger
E-105 fifth heat exchanger
M-101 membrane separator
M-1011 molecular sieve membrane group
P-101 feed pump
P-102 air pump
P-103 steam jet pump
V-101 storage tank
C-101 compressor
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Example 1
The utility model provides a device of separation methyl alcohol and dimethyl carbonate azeotrope of membrane separation coupling rectification, as shown in figure 1, including reaction rectifying column T-101, second heat exchanger E-102, third heat exchanger E-103, fifth heat exchanger E-105, membrane separator M-101, steam jet vacuum system P-103, charge pump P-101, atmospheric tower T-102, storage tank V-101. The top of the reaction rectifying tower T-101 is sequentially communicated with the third heat exchanger E-103 and the membrane separator M-101 through pipelines, the interception side outlet of the membrane separator M-101 is communicated with the inlet of the feed pump P-101 through a pipeline, the outlet of the feed pump P-101 is communicated with the middle part of the normal pressure tower T-102 through a pipeline, and the top of the normal pressure tower T-102 is sequentially communicated with the fifth heat exchanger E-105 and the interception side inlet of the membrane separator M-101 through pipelines; the outlet at the permeation side of the membrane separator M-101 is communicated with the suction port of a steam jet vacuum system P-103 through a pipeline, and the discharge port of the steam jet vacuum system P-103 is sequentially communicated with the middle lower part of the second heat exchanger E-102 and the reaction rectifying tower T-101 through pipelines. The storage tank V-101 is communicated with a second heat exchanger E-102 through a pipeline, and the membrane separator M-101 comprises a pervaporation membrane module.
The outlet of the membrane separator M-101 is provided with a permeation side outlet and a interception side outlet, the methanol-DMC azeotrope enters the membrane separator M-101 for separation of methanol and DMC after being cooled and condensed by a third heat exchanger E-103, the material from the permeation side outlet mainly contains methanol, the material from the interception side outlet is a methanol-DMC blend, and the DMC concentration in the blend is higher than the DMC concentration at the inlet of the membrane separator M-101.
In some embodiments, the pervaporation membrane is a molecular sieve membrane, the membrane separator M-101 comprises a plurality of stages of molecular sieve membrane groups M-1011 arranged in series, the outlet on the interception side of the upper stage of the molecular sieve membrane group M-1011 is connected with the inlet on the interception side of the lower stage of the molecular sieve membrane group M-1011, and the outlet on the permeation side of each stage of the molecular sieve membrane group M-1011 is connected in parallel and is communicated with the suction port of the steam jet vacuum system P-103. The multistage molecular sieve membrane group is used for separating the methanol-DMC azeotrope, and the methanol and DMC are separated more completely through the separation of the multistage molecular sieve membrane group.
In some embodiments, the steam jet vacuum system comprises a combination of five or six stage steam jet pumps to achieve the desired vacuum level; in some embodiments, as shown in fig. 2, the membrane separator M-101 includes a three-stage molecular sieve membrane group M-1011 arranged in series, and the molecular sieve membrane is an FAU molecular sieve membrane, which is verified by experiments to have an excellent separation effect on methanol-DMC azeotrope, and the separation effect in both pilot plant experiments and pilot plant experiments meets the process requirements.
In some embodiments, the apparatus of the present invention further comprises a propylene glycol refining column, wherein the bottom of the reactive distillation column T-101 is in communication with the propylene glycol refining column via a pipeline. Propylene glycol and DMC are generated simultaneously in the reaction of propylene carbonate and methanol in the reactive distillation tower T-101, and the propylene glycol product with the purity up to the standard is obtained after the propylene glycol is refined.
In some embodiments, the device of the utility model also comprises a first heat exchanger E-101, the bottom of the reaction rectifying tower T-101 is communicated with the inlet of the first heat exchanger E-101 through a pipeline, the outlet of the first heat exchanger E-101 is communicated with the reaction rectifying tower T-101 through a pipeline, the first heat exchanger E-101 is used for heating partial propylene glycol extracted from the bottom of the reaction rectifying tower T-101, the propylene glycol steam after heating and reboiling circularly enters the reaction rectifying tower T-101, the propylene glycol steam flows back upwards, and flows back downwards after being condensed by the methanol-DMC mixed liquid in the second heat exchanger, and the distillation process is continuously carried out through vapor-liquid two-phase contact mass transfer; except the propylene glycol which circularly enters the reaction rectifying tower in the first heat exchanger E-101 and the second heat exchanger E-102 through heat exchange with water vapor, most of the propylene glycol extracted from the bottom of the rest reaction rectifying tower T-101 enters the propylene glycol refining tower.
In some embodiments, the apparatus of the present invention further comprises a DMC purification tower, wherein the bottom of the atmospheric tower T-102 is in communication with the DMC purification tower through a pipeline, and most of DMC extracted from the atmospheric tower T-102 enters the DMC purification tower to be purified to obtain a qualified DMC product.
In some embodiments, the device of the utility model also comprises a fourth heat exchanger E-104, the bottom of the atmospheric tower T-102 is communicated with the inlet of the fourth heat exchanger E-104 through a pipeline, the outlet of the fourth heat exchanger E-104 is communicated with the middle lower part of the atmospheric tower T-102 through a pipeline, the fourth heat exchanger E-104 is used for reheating part of DMC extracted from the atmospheric tower T-102, heated DMC steam circulates to enter the atmospheric tower T-102 and is subjected to gas-liquid two-phase contact mass transfer with methanol-DMC mixed liquid condensed by the fifth heat exchanger E-105, and the continuous and stable operation of the rectification process in the atmospheric tower is ensured; and the rest DMC extracted from the bottom of the atmospheric tower T-102 enters a DMC refining tower.
In some embodiments, the first heat exchanger E-101, the second heat exchanger E-102 and the fourth heat exchanger E-104 are reboilers, the third heat exchanger E-103 and the fifth heat exchanger E-105 are condensers, and both the first heat exchanger and the fourth heat exchanger adopt low-pressure raw steam (water vapor) as a heat exchange working medium; the third heat exchanger and the fifth heat exchanger both adopt circulating cooling water as heat exchange working media; the second heat exchanger adopts medium and low pressure steam mixed by high pressure jet medium steam discharged by a steam jet vacuum system and methanol steam at the permeation side of the membrane component as a heat exchange medium.
In some embodiments, the apparatus of the present invention further comprises a compressor C-101, the compressor C-101 is connected to the inlet of the steam injection vacuum system P-103 via a pipeline for pressurizing the product steam, and the pressurized product steam enters the steam inlet of the steam injection vacuum system P-103 as the injection motive medium.
In some embodiments, the device of the present invention further comprises a vacuum pump P-102 connected to the third heat exchanger E-103, the vacuum pump P-102 being adapted to draw off exhaust gas remaining in the third heat exchanger E-103 in the device before the start of the reaction;
the outlet of the fifth heat exchanger E-105 is also communicated with the upper part of the atmospheric tower T-102 through a pipeline and is used for condensing part of methanol-DMC steam extracted from the top of the atmospheric tower T-102, condensate liquid reflows into the atmospheric tower T-102, and the rest methanol-DMC mixture extracted from the top of the atmospheric tower T-102 returns to the interception side of the membrane separator M-101 for separation again after being cooled by the fifth heat exchanger E-105.
According to current DMC methanol separation technology, combine molecular sieve membrane to get rid of methanol technical characterstic, the utility model provides a process flow of the device of separation methyl alcohol of membrane separation coupling rectification and dimethyl carbonate azeotrope is:
introducing raw materials of propylene carbonate, methanol and a catalyst into a reaction rectifying tower T-101 to react to generate DMC and propylene glycol, wherein DMC in a product and methanol in the raw materials form methanol-DMC azeotrope, the methanol-DMC azeotrope extracted from the top of the reaction rectifying tower T-101 contains about 70% of methanol, the methanol-DMC azeotrope enters a membrane separator M-101 after being cooled and condensed by a third heat exchanger E-103, the methanol content is reduced to about 40% once through, a material (methanol-DMC blend) extracted from an outlet at a interception side in the membrane separator M-101 enters an atmospheric tower T-102, the methanol-DMC azeotrope extracted from the top of the atmospheric tower T-102 returns to an inlet of the membrane separator M-101 again to carry out DMC/methanol membrane separation after being cooled and condensed by a fifth heat exchanger E-105, and the rest part of the methanol-DMC-azeotrope returns to the atmospheric tower T-102 through an upper inlet; most of DMC intermediate products which are extracted from the bottom of the atmospheric tower T-102 and contain more than 99 percent of DMC enter a DMC refining tower, the concentration of the DMC intermediate products is increased to more than 99.9 percent through the subsequent DMC refining tower, the rest part is heated and reboiled through a fourth heat exchanger E-104, and DMC steam returns to the inside of the atmospheric tower T-102 through a lower inlet. The steam jet vacuum system P-103 provides required vacuum degree for the pervaporation process of the membrane, the permeate which is discharged from the permeation side outlet of the membrane separator M-101 is mainly methanol, the content of the methanol is more than 98 percent, the permeate is in a negative pressure methanol steam state, the permeate is discharged from the permeation side of the membrane separator M-101 and enters the steam jet vacuum system P-103, the permeate is mixed with the high-pressure product steam which enters the steam jet vacuum system P-103 to obtain discharged medium and low pressure steam, and the latent heat of the methanol steam is fully recovered; and the middle-low pressure steam at the discharge port of the steam jet vacuum system P-103 heats part of propylene glycol feed liquid extracted from the bottom of the reaction rectifying tower T-101 through the second heat exchanger E-102, so that propylene glycol is reboiled to obtain propylene glycol steam, and the latent heat of the middle-low pressure steam discharged from the steam jet vacuum system P-103 is recovered, thereby further reducing the energy consumption.
Most of propylene glycol at the bottom of the reactive distillation tower T-101 directly enters a propylene glycol refining tower for refining, and the rest is heated by a first heat exchanger E-101 and a second heat exchanger E-102, wherein the first heat exchanger E-101 heats the propylene glycol by using water vapor, the second heat exchanger heats the propylene glycol by using medium and low pressure vapor at a discharge outlet of a vapor injection vacuum system P-103, and the heated propylene glycol reenters the lower part of the reactive distillation tower T-101 in a vapor form and is subjected to sufficient vapor-liquid two-phase contact mass transfer with methanol-DMC mixed liquid condensed by a third heat exchanger, so that the stable operation of the distillation process is ensured.
The product vapor injection medium of vapor injection vacuum system P-103 can be either methanol or propylene carbonate. When methanol is selected as the spraying medium, the spraying medium is mixed with methanol vapor permeated from the membrane separator M-101, and a part of the spraying medium mixed material is returned to the reactive distillation column T-101 after heat exchange of the second heat exchanger E-102, and a part of the spraying medium mixed material enters the storage tank V-101. When propylene carbonate is selected as a spraying medium, the spraying medium is mixed with methanol steam to obtain a methanol-propylene carbonate mixed material, and the spraying medium mixed material enters the storage tank V-101 after heat exchange by the second heat exchanger E-102 and can be used for other chemical reactions needing premixing the propylene carbonate and the methanol.
Compare the device of former pressurization rectification technology, the utility model discloses the whole operation of device no longer needs middling pressure steam, and pressurization operating condition cancels, and running cost such as energy consumption reduces by a wide margin. The utility model discloses still make innovative improvement to the vacuum system among the membrane separation process, introduce and use propylene carbonate or methyl alcohol to spray the steam injection vacuum system of power supply as, replace the vacuum pump among the traditional membrane separation, can not only provide the required vacuum of membrane separation, can also effectively retrieve the latent heat of methyl alcohol steam simultaneously, the material of steam injection vacuum system discharge port carries out the recovery of steam latent heat for the heat supply of reaction rectifying column cauldron in addition, further reduces the energy consumption.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.
Claims (11)
1. A device for separating methanol and dimethyl carbonate azeotrope by membrane separation coupling rectification is characterized in that: comprises a reaction rectifying tower, a second heat exchanger, a third heat exchanger, a fifth heat exchanger, a membrane separator, a steam jet vacuum system, a feed pump, an atmospheric tower and a storage tank;
the top of the reaction rectifying tower is sequentially communicated with the third heat exchanger and the membrane separator through pipelines, an outlet of a interception side of the membrane separator is communicated with an inlet of the feed pump through a pipeline, an outlet of the feed pump is communicated with the middle part of the normal pressure tower through a pipeline, and the top of the normal pressure tower is sequentially communicated with the fifth heat exchanger and an inlet of the interception side of the membrane separator through pipelines; the outlet at the permeation side of the membrane separator is communicated with the suction port of the steam jet vacuum system through a pipeline, and the discharge port of the steam jet vacuum system is sequentially communicated with the second heat exchanger and the middle lower part of the reaction rectifying tower through pipelines;
the storage tank is communicated with the second heat exchanger through a pipeline, and the membrane separator comprises a pervaporation membrane module.
2. The apparatus of claim 1, wherein:
the steam jet vacuum system comprises a multi-stage steam jet pump;
the pervaporation membrane is a molecular sieve membrane, the membrane separator comprises a plurality of stages of molecular sieve membrane groups which are arranged in series, an interception side outlet of the upper stage of molecular sieve membrane group is connected with an interception side inlet of the lower stage of molecular sieve membrane group, and a permeation side outlet of each stage of molecular sieve membrane group is connected in parallel and is communicated with a suction port of the steam jet vacuum system.
3. The apparatus of claim 2, wherein:
the steam jet vacuum system comprises a five-stage or six-stage steam jet pump;
the membrane separator comprises three-stage molecular sieve membrane groups which are arranged in series, and the molecular sieve membrane is an FAU molecular sieve membrane.
4. The apparatus of claim 1, wherein: the device also comprises a propylene glycol refining tower, wherein the bottom of the reaction rectifying tower is communicated with the propylene glycol refining tower through a pipeline.
5. The apparatus of claim 4, wherein: the bottom of the reaction rectifying tower is communicated with the inlet of the first heat exchanger through a pipeline, the outlet of the first heat exchanger is communicated with the reaction rectifying tower through a pipeline, the first heat exchanger is used for heating propylene glycol extracted from the bottom of the reaction rectifying tower, the heated propylene glycol circularly enters the reaction rectifying tower, propylene glycol steam flows back upwards, the propylene glycol steam flows back downwards after being condensed by methanol-DMC mixed liquid in the second heat exchanger, and the steam-liquid two-phase contact mass transfer is realized, so that the rectifying process is continuously carried out.
6. The apparatus of claim 5, wherein: the first heat exchanger and the second heat exchanger are reboilers, the third heat exchanger and the fifth heat exchanger are condensers, and the first heat exchanger is a heat exchanger adopting low-pressure raw steam as a heat exchange working medium; the third heat exchanger and the fifth heat exchanger both adopt circulating cooling water as heat exchange working media; the second heat exchanger adopts medium and low pressure steam mixed by high pressure jet medium steam discharged by a steam jet vacuum system and methanol steam at the permeation side of the membrane component as a heat exchange medium.
7. The apparatus of claim 1, wherein: the device also comprises a DMC refining tower, wherein the bottom of the atmospheric tower is communicated with the DMC refining tower through a pipeline, and DMC extracted from the atmospheric tower enters the DMC refining tower to be refined to obtain a standard DMC product.
8. The apparatus of claim 7, wherein: the bottom of the atmospheric tower is communicated with an inlet of the fourth heat exchanger through a pipeline, an outlet of the fourth heat exchanger is communicated with the atmospheric tower through a pipeline, the fourth heat exchanger is used for reheating part of DMC extracted from the atmospheric tower, heated DMC steam circularly enters the atmospheric tower and carries out gas-liquid two-phase contact mass transfer with methanol-DMC mixed liquid condensed by the fifth heat exchanger, and continuous and stable operation of a rectification process in the atmospheric tower is guaranteed.
9. The apparatus of claim 8, wherein: the fourth heat exchanger is a reboiler, and the fourth heat exchanger is a heat exchanger adopting low-pressure raw steam as a heat exchange working medium.
10. The apparatus of claim 1, wherein: the steam injection vacuum system is characterized by further comprising a compressor, wherein the compressor is communicated with an inlet of the steam injection vacuum system through a pipeline and used for pressurizing product steam, and the pressurized product steam enters the steam injection vacuum system to be used as an injection medium.
11. The apparatus of claim 1, wherein: the vacuum pump is used for pumping the waste gas generated in the third heat exchanger before the reaction starts;
and the outlet of the fifth heat exchanger is also communicated with the upper part of the atmospheric tower through a pipeline and is used for condensing part of methanol-DMC steam extracted from the top of the atmospheric tower and refluxing condensate into the atmospheric tower.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115572215A (en) * | 2022-10-24 | 2023-01-06 | 浙江汇甬新材料有限公司 | Separation method of methanol and dimethyl carbonate azeotrope by membrane separation coupled rectification |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115572215A (en) * | 2022-10-24 | 2023-01-06 | 浙江汇甬新材料有限公司 | Separation method of methanol and dimethyl carbonate azeotrope by membrane separation coupled rectification |
| CN115572215B (en) * | 2022-10-24 | 2024-04-30 | 浙江汇甬新材料有限公司 | Separation method of methanol and dimethyl carbonate azeotrope through coupling and rectification of membrane separation |
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