CN115317946A - Device and method for purifying ethylene glycol monopropyl ether by coupling rectification - Google Patents
Device and method for purifying ethylene glycol monopropyl ether by coupling rectification Download PDFInfo
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- YEYKMVJDLWJFOA-UHFFFAOYSA-N 2-propoxyethanol Chemical compound CCCOCCO YEYKMVJDLWJFOA-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 230000008878 coupling Effects 0.000 title claims abstract description 34
- 238000010168 coupling process Methods 0.000 title claims abstract description 34
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000006837 decompression Effects 0.000 claims description 92
- 239000000463 material Substances 0.000 claims description 63
- 239000007788 liquid Substances 0.000 claims description 29
- 238000010438 heat treatment Methods 0.000 claims description 17
- 238000010992 reflux Methods 0.000 claims description 11
- 238000009833 condensation Methods 0.000 claims description 8
- 230000005494 condensation Effects 0.000 claims description 8
- 239000012043 crude product Substances 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 8
- 238000011084 recovery Methods 0.000 claims description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 abstract description 53
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 238000000746 purification Methods 0.000 abstract description 7
- 238000000926 separation method Methods 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 230000008569 process Effects 0.000 abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 239000012847 fine chemical Substances 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 27
- 239000000047 product Substances 0.000 description 17
- DJCYDDALXPHSHR-UHFFFAOYSA-N 2-(2-propoxyethoxy)ethanol Chemical compound CCCOCCOCCO DJCYDDALXPHSHR-UHFFFAOYSA-N 0.000 description 12
- 238000009835 boiling Methods 0.000 description 8
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003905 agrochemical Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000019658 bitter taste Nutrition 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000001944 continuous distillation Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 150000002894 organic compounds Chemical group 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000005292 vacuum distillation Methods 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
- B01D3/10—Vacuum distillation
-
- 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
-
- 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
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
- C07C41/01—Preparation of ethers
- C07C41/34—Separation; Purification; Stabilisation; Use of additives
- C07C41/40—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation
- C07C41/42—Separation; Purification; Stabilisation; Use of additives by change of physical state, e.g. by crystallisation 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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- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention belongs to a purification process of fine chemical products, and particularly relates to a device and a method for purifying ethylene glycol monopropyl ether by coupling rectification. The invention realizes the continuity of the rectification and purification process of the ethylene glycol monopropyl ether, realizes the separation and purification of each product, and ensures that the purity of the ethylene glycol monopropyl ether product and the purity of the recovered n-propanol can respectively reach 99 percent; the device and the method provided by the invention greatly reduce the energy consumption in the rectification process and simultaneously reduce the carbon emission in the production process.
Description
Technical Field
The invention belongs to a purification process of fine chemical products, and particularly relates to a device and a method for purifying ethylene glycol monopropyl ether by coupling rectification.
Background
Ethylene glycol mono-n-propyl ether is an organic compound with the chemical formula C 5 H 12 O 2 It is colorless or yellow odorous liquid, has slight diethyl ether and bitter taste, is soluble in organic solvent such as ethanol and acetone, and is miscible with water. It is mainly used as raw material for synthesizing agricultural chemicals, and also can be used as solvent in nitrocellulose and paint industry.
At present, ethylene glycol monopropyl ether is usually prepared by the intermittent reaction of n-propanol and ethylene oxide in a reaction kettle under the action of a catalyst, and then separation and purification are realized by intermittent reduced pressure distillation. The intermittent vacuum distillation method has the defects that the parameters of the production process are continuously changed, the method is not suitable for large-scale industrial production and has higher energy consumption, and the continuous distillation process is used as the traditional separation technology and has the defect of huge energy consumption. High energy consumption necessarily results in higher production costs and also in greater carbon dioxide emissions, and therefore, if a low energy consumption technology for continuous production is used, it is of great significance to mass production of the product, reduction of production costs and reduction of carbon emissions.
The coupling rectification technology and the heat pump rectification technology are applied to the rectification process, and have important value for saving energy in the rectification process. For an ethylene glycol monopropyl ether system, the boiling point of part of the system is higher, wherein the boiling point of n-propanol is 90.5 ℃, the boiling point of ethylene glycol monopropyl ether is 150-152 ℃, and the boiling point of diethylene glycol monopropyl ether reaches 212-216 ℃; high boiling point requires high temperature heating medium or vacuum rectification; the application of the general heat pump rectification technology is difficult due to the large boiling point difference of the components to be separated.
In view of this, the present invention is proposed.
Disclosure of Invention
The invention hopes to provide a device and a method for purifying ethylene glycol monopropyl ether by coupling rectification, and the specific scheme is as follows:
the device for purifying the ethylene glycol monopropyl ether by coupling rectification comprises a first preheater, a pressurizing tower, a first decompression tower and a second decompression tower which are sequentially connected, wherein the pressurizing tower is communicated with the first decompression tower to form a loop, and the first decompression tower or the second decompression tower is communicated with the first preheater to form a loop.
A first reboiler is arranged on one side of the pressurizing tower, a second reboiler is arranged on one side of the second pressure reducing tower, the first reboiler can heat the material extracted from the tower kettle of the pressurizing tower into a gas-liquid mixture, the gas-liquid mixture enters the pressurizing tower and is separated into a gas phase and a liquid phase, and the gas phase becomes ascending steam at the bottom of the tower; the second reboiler can heat the material extracted from the second vacuum tower into a gas-liquid mixture, the gas-liquid mixture enters the second vacuum tower and is separated into a gas phase and a liquid phase, and the gas phase becomes ascending steam at the bottom of the tower.
A coupling reboiler, a recovery liquid tank and a first pump are arranged between the pressurizing tower and the first decompressing tower, reflux is formed between the coupling reboiler and the first decompressing tower, reflux is also formed between the coupling reboiler and the pressurizing tower, and materials (heat) extracted from the top of the pressurizing tower and materials (cold) extracted from the bottom of the first decompressing tower exchange heat through the coupling reboiler (the coupling reboiler is a condenser for the pressurizing tower and a reboiler for the first decompressing tower, so the coupling reboiler is called as the coupling reboiler).
And a condenser is arranged on one side of the first decompression tower, part of the material obtained from the top of the first decompression tower is extracted, and part of the material is cooled by the condenser and then flows back into the first decompression tower.
A first compressor, a first condensate collecting tank and a second pump are arranged between the first decompression tower or the second decompression tower and the first preheater, and a gas-phase material at the top of the second decompression tower is pressurized by the first compressor, enters the preheater and is used as a heating source of a crude product and is condensed by the preheater; and the condensed liquid enters a first condensed liquid collecting tank, is pressurized by a second pump, partially flows back into a second decompression tower, and the other part is extracted as a product (n-propanol).
A second preheater is arranged between the first decompression tower and the second decompression tower, a second compressor, a second condensate collecting tank and a third pump are arranged between the second preheater and the second decompression tower, and a gas-phase material at the top of the second decompression tower enters the second preheater as a heating source of the feeding of the second decompression tower after being pressurized by the second compressor and is condensed by the second preheater; and the condensed liquid enters a second condensed liquid collecting tank, is pressurized by a third pump, and then partially flows back to enter a second decompression tower, and the other part is taken as a product (diethylene glycol monopropyl ether).
A method for purifying ethylene glycol monopropyl ether by coupling rectification comprises the following specific steps:
(1) Preheating a crude product of ethylene glycol monopropyl ether by a first preheater, then feeding the crude product into a pressurizing tower for rectification, introducing a gas-phase material (n-propanol) extracted from the tower top into one side of a coupling reboiler as a heat source, simultaneously condensing the gas-phase material (realizing thermal coupling), feeding the condensed material into a recovery liquid tank, pressurizing by a first pump, feeding one part of the condensed material into the tower top of the pressurizing tower as reflux, and directly extracting the other part of the condensed material;
(2) Introducing a material (a mixture of ethylene glycol monopropyl ether, diethylene glycol monopropyl ether and n-propanol) extracted from the bottom of a pressurizing tower into a first decompression tower for decompression and rectification, pressurizing a gas-phase material (n-propanol) part at the top of the first decompression tower by a first compressor, increasing the temperature (by a heat pump technology), and using the gas-phase material as a heating source of the first preheater, wherein the gas-phase material is condensed in the first preheater, and a crude raw material is preheated; meanwhile, the other part of the gas-phase material at the top of the first decompression tower enters a condenser for condensation, the condensate after heat exchange of the first preheater enters a first condensate collecting tank, then is converged with the condensate after condensation of the condenser through a second pump, part of the converged condensate flows back to the first decompression tower, and part of the condensed condensate is directly extracted; or the condensate of the gas-phase material at the top of the first decompression tower condensed by the condenser is respectively refluxed into the first decompression tower and directly extracted;
(3) The method comprises the following steps that materials (ethylene glycol monopropyl ether and diethylene glycol monopropyl ether) extracted from the bottom of a first decompression tower directly enter a second decompression tower or enter the second decompression tower through a second preheater for decompression rectification, a gas-phase material (ethylene glycol monopropyl ether) at the top of the second decompression tower is pressurized through a second compressor, the temperature is raised, the gas-phase material can be used as a heating source of the second preheater, the gas-phase material is condensed in the second preheater, the material extracted from the bottom of the first decompression tower is preheated, a condensed liquid enters a second condensate collecting tank and is pressurized through a third pump, part of the condensed liquid flows back to the second decompression tower, and the other part of the condensed liquid is directly extracted; or as in the step (2), after the gas-phase material is treated by the first compressor, the first preheater, the first condensate collecting tank and the second pump, part of the obtained condensate flows back to the second decompression tower, and part of the condensate is directly extracted.
The working pressure of the pressurizing tower is 0.25-0.6MPa.A, the temperature at the bottom of the tower is 135-150 ℃, and the temperature at the top of the tower is 123-135 ℃.
The working pressure of the first decompression tower is 0.02-0.035Mpa, the temperature of the tower kettle of the first decompression tower is 105-116.3 ℃, and the working pressure of the first decompression tower is lower than that of the pressurizing tower, so the extraction at the tower kettle of the pressurizing tower can flow into the first decompression tower through pressure difference.
The working pressure of the second decompression tower is 0.01-0.025MPa.
The invention has the following beneficial effects:
1. the method realizes the continuity of the rectification and purification process of the ethylene glycol monopropyl ether, realizes the separation and purification of each product, and ensures that the purity of the ethylene glycol monopropyl ether product and the purity of the recovered n-propanol can respectively reach 99 percent;
2. the device and the method provided by the invention greatly reduce the energy consumption in the rectification process and simultaneously reduce the carbon emission in the production process.
Drawings
FIG. 1 is a schematic structural diagram I of a device for purifying ethylene glycol monopropyl ether by coupling rectification according to the present invention;
FIG. 2 is a schematic structural diagram II of a device for purifying ethylene glycol monopropyl ether by coupling rectification according to the present invention;
wherein the reference numbers: the system comprises a pressurizing tower 1, a first depressurizing tower 2, a second depressurizing tower 3, a first preheater 4, a first pump 5, a first reboiler 6, a coupling reboiler 7, a recycle liquid tank 8, a second preheater 9, a third pump 10, a second reboiler 11, a second compressor 12, a first compressor 13, a condenser 14, a first condensate collecting tank 15, a second condensate collecting tank 16, a second pump 17 and a fourth pump 18.
Detailed Description
The present invention will be further described with reference to the following embodiments.
Example 1
As shown in figure 1, crude ethylene glycol monopropyl ether (containing n-propanol 63 wt.%, ethylene glycol monopropyl ether content 30 wt.% and diethylene glycol monopropyl ether 7 wt.%) from a polymerization reactor is preheated by a first preheater 4 and then enters a pressurized column 1 for rectification. A coupling reboiler 7 is arranged between the pressurizing tower 1 and the first decompressing tower 2, the working pressure of the pressurizing tower 1 is 0.25-0.6MPa.A, the tower bottom temperature is 135-150 ℃, and the tower top temperature is 123-135 ℃.
In the pressurizing tower 1, the normal propyl alcohol is firstly primarily separated from the other two substances, the normal propyl alcohol product is extracted from the top of the pressurizing tower 1, the normal propyl alcohol steam enters one side of the coupling reboiler 7 to be used as a heating source, and meanwhile, the steam is condensed, so that the heating steam of the first decompressing tower 2 (the material at the bottom of the first decompressing tower 2 is subjected to heat exchange through the coupling reboiler 7 and then enters the first decompressing tower 2) and the condensation water at the top of the pressurizing tower 1 (the condensation liquid refers to the material, and the condensation water refers to the cooling medium of the condenser at the top of the tower) can be saved. After condensed n-propanol enters a recovery liquid tank 8 for collection, after the n-propanol is pressurized by a first pump 5, one part of the condensed n-propanol enters the top of a pressurizing tower 1 as reflux, and the other part of the condensed n-propanol is directly extracted as the synthesis raw material of ethylene glycol monopropyl ether as the extracted (n-propanol).
The material still containing more n-propanol, ethylene glycol monopropyl ether and diethylene glycol monopropyl ether is extracted from the tower kettle of the pressurizing tower 1. Wherein, part of the materials enter the first decompression tower 2 for decompression and rectification, the other part of the materials enter the bottom of the pressurizing tower 1 after being vaporized by the first reboiler 6, the working pressure in the first decompression tower 2 is 0.02-0.035Mpa.A, and the tower bottom extraction of the pressurizing tower 1 can flow into the first decompression tower 2 through pressure difference because the working pressure in the first decompression tower 2 is lower than that in the pressurizing tower 1. In addition, since the operating pressures of the pressurizing column 1 and the first depressurizing column 2 are different from each other, a temperature condition (satisfying a heat exchange condition) is provided in which the condensing temperature of the pressurizing column 1 is higher than the boiling point of the coupling reboiler 7. The temperature of the bottom of the first decompression tower 2 is 105-116.3 ℃, and the coupling reboiler 7 adopts the gas phase material at the top of the pressurizing tower 1 as a heating heat source, so that no additional heat source is needed. The gas phase material at the top of the first decompression tower 2 is respectively refluxed and extracted after being condensed by a condenser 14, and the gas phase material is extracted as a finished product of n-propanol and used as a reaction raw material of ethylene glycol monopropyl ether.
The materials extracted from the bottom of the first vacuum tower 2 mainly comprise ethylene glycol monopropyl ether and diethylene glycol monopropyl ether, and the materials are conveyed into a second vacuum tower 3 through a fourth pump 18 to carry out rectification separation on the ethylene glycol monopropyl ether and the diethylene glycol monopropyl ether. The working pressure of the second decompression tower 3 is 0.01-0.025MPa, and in the second decompression tower 3, the gas-phase material at the top of the tower is pressurized by a first compressor 13, enters a first preheater 4 to heat a crude product and is condensed by the first preheater 4; the condensed liquid enters a first condensate collecting tank 15, is pressurized by a second pump 17, then enters a part of the second decompression tower 3 as reflux, the other part of the condensed liquid is taken as a product (ethylene glycol monopropyl ether) to be extracted, a finished product of the ethylene glycol monopropyl ether is extracted from the tower bottom, and a part of the finished product of the ethylene glycol monopropyl ether enters the tower bottom of the second decompression tower 3 after being vaporized by a second reboiler 11.
The device and the method can reduce the consumption of heating steam by 61%, reduce the consumption of circulating cooling water by 58% and realize the emission reduction of carbon dioxide by 3320t/a for the production of 2 million tons of ethylene glycol monopropyl ether annually.
Example 2
As shown in FIG. 2, crude ethylene glycol monopropyl ether (containing n-propanol 65 wt%, ethylene glycol monopropyl ether content 30 wt% and diethylene glycol monopropyl ether 5 wt%) from a polymerization reactor is preheated by a first preheater 4 and then enters a pressurized column 1 for rectification. A coupling reboiler 7 is disposed between the pressurizing column 1 and the first depressurizing column 2. The working pressure of the pressurizing tower 1 is 0.25-0.6MPa.A, the temperature at the bottom of the tower is 135-150 ℃, and the temperature at the top of the tower is 123-135 ℃.
In the pressurizing tower 1, the normal propyl alcohol is firstly primarily separated from the other two substances, the normal propyl alcohol product is extracted from the top of the pressurizing tower 1, the normal propyl alcohol steam firstly enters one side of the coupling reboiler 7 to be used as a heating heat source, and meanwhile, the steam is condensed, so that the heating steam of the first decompressing tower 2 and the condensing water on the top of the pressurizing tower 1 can be saved, and the top condenser of the pressurizing tower 1 is saved. After condensed n-propanol enters a recovery liquid tank 8 for collection, after the n-propanol is pressurized by a first pump 5, one part of the condensed n-propanol enters the top of a pressurizing tower 1 as reflux, and the other part of the condensed n-propanol is directly extracted as the synthesis raw material of ethylene glycol monopropyl ether as the extracted (n-propanol).
The material still containing more n-propanol, ethylene glycol monopropyl ether and diethylene glycol monopropyl ether is extracted from the tower bottom of the pressurizing tower 1. One part of the material enters a first decompression tower 2 for decompression and rectification, and the other part of the material enters the bottom of a pressurizing tower 1 after being vaporized by a first reboiler 6. The working pressure in the first decompression tower 2 is 0.02-0.035Mpa, and the pressure in the first decompression tower 2 is lower than that in the pressurizing tower 1, so the extraction in the tower bottom of the pressurizing tower 1 can flow into the first decompression tower 2 through pressure difference. In addition, since the operating pressures of the pressurizing column 1 and the first depressurizing column 2 are different from each other, the condition is satisfied that the condensing temperature of the pressurizing column 1 is higher than the boiling point temperature of the coupling reboiler 7. The temperature of the bottom of the first decompression tower 2 is 105-116.3 ℃, and the coupling reboiler 7 adopts the gas phase material at the top of the pressurizing tower 1 as a heating medium, so that no additional heat source is needed. After the gas-phase material part at the top of the first decompression tower 2 is pressurized by a first compressor 13, the temperature is raised to 116-123 ℃, and the gas-phase material part can be used as a heating heat source of a first preheater 4 (in the first preheater 4, the gas-phase material is condensed, and a crude raw material is preheated); and the other part of the gas-phase material at the top of the first decompression tower 2 enters a condenser 14 for condensation, after two streams of condensate (the condensate condensed in the condenser 14 and the condensate obtained by heat exchange in the first preheater 4) are converged, part of the condensate flows back into the first decompression tower 2 according to the control requirement of the reflux ratio, and part of the condensate is extracted to be used as a finished product of n-propanol which is used as a reaction raw material of ethylene glycol monopropyl ether.
The materials extracted from the bottom of the first vacuum tower 2 mainly comprise ethylene glycol monopropyl ether and diethylene glycol monopropyl ether, and the materials are conveyed into a second vacuum tower 3 through a fourth pump 18 to carry out rectification separation on the ethylene glycol monopropyl ether and the diethylene glycol monopropyl ether. The working pressure of the second decompression tower 3 is 0.01-0.025MPa. In the second decompression tower 3, the gas phase material at the top of the tower is pressurized by a second compressor 12, enters a second preheater 9 as a heating heat source for feeding the second decompression tower 3, is condensed by itself, the condensed liquid enters a second condensate collecting tank 16, is pressurized by a third pump 10, part of the condensed liquid enters the second decompression tower 3 as reflux, the other part of the condensed liquid is taken as a product (ethylene glycol monopropyl ether), the finished product of the ethylene glycol monopropyl ether is taken at the bottom of the tower, and the finished product of the ethylene glycol monopropyl ether is vaporized by a second reboiler 11 and then enters the bottom of the second decompression tower 3.
For the crude product with the processing capacity of the scale, compared with the common batch rectification, the rectification method realizes the continuous and large-scale industrial production, realizes the stable separation of the main product and the byproduct, and has stable parameters in the production operation process and easy control. For the production of 1 ten thousand tons of ethylene glycol monopropyl ether per year, the method and the device can reduce the consumption of heating steam by 67 percent, reduce the consumption of circulating cooling water by 65 percent and realize the emission reduction of 1140t of annual carbon dioxide.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. A device for purifying ethylene glycol monopropyl ether by coupling rectification is characterized in that: the system comprises a first preheater, a pressurizing tower, a first decompression tower and a second decompression tower which are sequentially connected, wherein the pressurizing tower is communicated with the first decompression tower to form a loop, and the first decompression tower or the second decompression tower is communicated with the first preheater to form a loop.
2. The apparatus for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 1, wherein: and a first reboiler is arranged on one side of the pressurizing tower, and a second reboiler is arranged on one side of the second decompression tower.
3. The device for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 1, wherein: a coupling reboiler, a recovery liquid tank and a first pump are arranged between the pressurizing tower and the first depressurizing tower, reflux is formed between the coupling reboiler and the first depressurizing tower, and reflux is also formed between the coupling reboiler and the pressurizing tower.
4. The device for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 1, wherein: and a condenser is arranged on one side of the first decompression tower.
5. The device for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 1, wherein: and a first compressor, a first condensate collecting tank and a second pump are arranged between the first decompression tower or the second decompression tower and the first preheater.
6. The device for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 1, wherein: and a second preheater is arranged between the first decompression tower and the second decompression tower, and a second compressor, a second condensate collecting tank and a third pump are arranged between the second preheater and the second decompression tower.
7. The method for purifying ethylene glycol monopropyl ether by coupled rectification according to claim 1, which is characterized by comprising the following steps:
(1) Preheating a crude product of ethylene glycol monopropyl ether by a first preheater, then feeding the crude product into a pressurizing tower for rectification, introducing a gas-phase material extracted from the tower top into one side of a coupling reboiler as a heating source, simultaneously condensing the gas-phase material, feeding the condensed material into a recovery liquid tank, pressurizing by a first pump, feeding one part of the condensed material into the tower top of the pressurizing tower as reflux, and directly extracting the other part of the condensed material;
(2) Introducing the material extracted from the bottom of the pressurizing tower into a first decompression tower for decompression and rectification, pressurizing the gas-phase material part at the top of the first decompression tower by a first compressor, raising the temperature, and using the gas-phase material part as a heat source of a first preheater, wherein in the first preheater, the gas-phase material is condensed, and the crude product raw material is preheated; meanwhile, the other part of the gas-phase material at the top of the first decompression tower enters a condenser for condensation, the condensate after heat exchange in the first preheater enters a first condensate collecting tank, then is converged with the condensate after condensation of the condenser through a second pump, part of the converged condensate flows back to the first decompression tower, and part of the condensed condensate is directly extracted; or the condensed liquid of the gas-phase material at the top of the first decompression tower condensed by the condenser respectively reflows to the first decompression tower and is directly extracted;
(3) The material extracted from the bottom of the first decompression tower directly enters or enters a second decompression tower through a second preheater for decompression rectification, the gas-phase material at the top of the second decompression tower is pressurized by a second compressor, the temperature is raised and can be used as a heating source of the second preheater, the gas-phase material is condensed in the second preheater, the material extracted from the bottom of the first decompression tower is preheated, the condensed liquid enters a second condensate collecting tank and is pressurized by a third pump, part of the condensed liquid flows back to enter the second decompression tower, and the other part of the condensed liquid is directly extracted; or as in the step (2), after the gas-phase material is treated by the first compressor, the first preheater, the first condensate collecting tank and the second pump, part of the obtained condensate flows back to the second decompression tower, and part of the condensate is directly extracted.
8. The method for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 7, wherein: the working pressure of the pressurizing tower is 0.25-0.6MPa.A, the temperature at the bottom of the tower is 135-150 ℃, and the temperature at the top of the tower is 123-135 ℃.
9. The method for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 7, wherein: the working pressure of the first decompression tower is 0.02-0.035Mpa, and the temperature of the kettle of the first decompression tower is 105-116.3 ℃.
10. The method for purifying ethylene glycol monopropyl ether by coupled rectification as claimed in claim 7, wherein: the working pressure of the second decompression tower is 0.01-0.025MPa.
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