CN114456039A - Partition wall tower type isopropanol solution molecular sieve membrane distillation separation and purification method - Google Patents
Partition wall tower type isopropanol solution molecular sieve membrane distillation separation and purification method Download PDFInfo
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- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 title claims abstract description 308
- 239000012528 membrane Substances 0.000 title claims abstract description 158
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 77
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000004821 distillation Methods 0.000 title claims abstract description 24
- 238000005192 partition Methods 0.000 title claims description 43
- 238000000926 separation method Methods 0.000 title claims description 39
- 238000000746 purification Methods 0.000 title claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 84
- 230000018044 dehydration Effects 0.000 claims abstract description 56
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 56
- 239000007788 liquid Substances 0.000 claims abstract description 48
- 238000007670 refining Methods 0.000 claims abstract description 31
- XTUSEBKMEQERQV-UHFFFAOYSA-N propan-2-ol;hydrate Chemical compound O.CC(C)O XTUSEBKMEQERQV-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910002056 binary alloy Inorganic materials 0.000 claims abstract description 22
- 239000012466 permeate Substances 0.000 claims abstract description 20
- 239000000047 product Substances 0.000 claims abstract description 20
- 238000013021 overheating Methods 0.000 claims abstract description 5
- 239000012071 phase Substances 0.000 claims description 50
- 239000000243 solution Substances 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 27
- 238000005373 pervaporation Methods 0.000 claims description 21
- 238000007599 discharging Methods 0.000 claims description 9
- 239000007791 liquid phase Substances 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 238000009833 condensation Methods 0.000 claims description 6
- 230000005494 condensation Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 238000001179 sorption measurement Methods 0.000 claims description 6
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical class CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- 229910001385 heavy metal Inorganic materials 0.000 claims description 4
- 239000012510 hollow fiber Substances 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 4
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 239000002041 carbon nanotube Substances 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 229920001661 Chitosan Polymers 0.000 claims description 2
- 229910021536 Zeolite Inorganic materials 0.000 claims description 2
- 239000011203 carbon fibre reinforced carbon Substances 0.000 claims description 2
- 239000000919 ceramic Substances 0.000 claims description 2
- 239000002131 composite material Substances 0.000 claims description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 2
- 229920005597 polymer membrane Polymers 0.000 claims description 2
- 238000011084 recovery Methods 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 235000010413 sodium alginate Nutrition 0.000 claims description 2
- 229940005550 sodium alginate Drugs 0.000 claims description 2
- 239000000661 sodium alginate Substances 0.000 claims description 2
- 239000010457 zeolite Substances 0.000 claims description 2
- 238000002207 thermal evaporation Methods 0.000 abstract 2
- 238000010533 azeotropic distillation Methods 0.000 description 9
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000009835 boiling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002309 gasification Methods 0.000 description 2
- 230000003204 osmotic effect Effects 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- QABJMMRWLGSUNH-UHFFFAOYSA-N cyclohexane;propan-2-ol;hydrate Chemical compound O.CC(C)O.C1CCCCC1 QABJMMRWLGSUNH-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 150000002191 fatty alcohols Chemical class 0.000 description 1
- JYVHOGDBFNJNMR-UHFFFAOYSA-N hexane;hydrate Chemical compound O.CCCCCC JYVHOGDBFNJNMR-UHFFFAOYSA-N 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 230000026676 system process Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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- 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
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention discloses a separating and purifying method of separating and purifying isopropanol solution by membrane distillation, wherein the isopropanol solution enters the middle part of a dehydration section divided into two sides by a hollow clapboard in a rectifying tower to carry out I-phase region rectification of an isopropanol-water binary system, water is discharged from the bottom, the top distillate gas enters a molecular sieve membrane separator A, the permeate from the permeation side forms liquid water after heat exchange and vacuum condensation through a hollow clapboard channel, the gas from the non-permeation side partially returns to an inlet of a overheating coil pipe to enter the membrane separator A/B to adjust the permeation quantity and water permeation pressure in the membrane separator, the liquid formed by a condenser partially enters an isopropanol refining section to carry out rectification in a II-phase region, the isopropanol product with the purity of more than or equal to 99.9 percent is distilled from the bottom, the gas phase distillate generated at the top enters a molecular sieve membrane B, the permeate from the permeation side forms liquid water after heat exchange and vacuum condensation through a hollow clapboard channel, and the liquid water is discharged, and (3) returning all the gas flowing out of the non-permeation side into a liquid formed by a condenser to the phase II region for rectification, wherein the yield of the isopropanol product is 100%.
Description
Technical Field
The invention belongs to the field of preparation of high-purity isopropanol by dehydration separation and purification of isopropanol solution, and particularly relates to a partition tower type isopropanol solution molecular sieve membrane rectification separation and purification method.
Background
The concentration of a crude isopropanol aqueous solution (hereinafter referred to as an "isopropanol solution") obtained by a hydration method is about 20-60% (w/w), the water concentration is 40-80%, and other small amount of impurities include organic matters such as fatty alcohols and the like and trace amount of water-soluble heavy metal impurities, and the isopropanol aqueous solution needs to be further dehydrated and purified to obtain an isopropanol product with higher purity, for example, the purity is greater than or equal to 99.9% (w/w). However, since isopropanol and water form an azeotrope, for example, the azeotropic composition at atmospheric pressure consists of 87.4% isopropanol concentration, 12.6% water, 80.31 ℃ azeotropic temperature, 82.45 ℃ boiling point of isopropanol at atmospheric pressure, 100 ℃ water, and the azeotrope formed by the isopropanol-water solution is a binary azeotropic system with the lowest boiling point. Therefore, general rectification cannot be achieved to obtain isopropanol with higher purity, and special separation methods such as azeotropic (co) rectification with an azeotropic agent (benzene, etc.), energy-saving azeotropic rectification with a dividing wall column, extractive rectification with an extractant (ethylene glycol, etc.), salt-added extractive rectification, gap extractive rectification, pressure swing rectification, membrane distillation, etc. must be used. The method comprises a special rectification method, a pervaporation membrane, a membrane contactor, a Temperature Swing Adsorption (TSA), adsorption rectification combined with adsorption and rectification and the like, and is used for separating and purifying the isopropanol solution, wherein the adsorption rectification is a brand new isopropanol dehydration process.
The existing Dividing Wall Column azeotropic Distillation (DWC) method is to arrange a vertical partition in a common rectifying Column, which is equivalent to a Petlyuk Column (thermocouple distillation or side line stripping) in thermodynamics, the addition of the partition realizes the functions of two columns, namely 3 pure component products (isopropanol, water and cyclohexane entrainer) can be obtained by only one rectifying Column, compared with the conventional two-Column azeotropic distillation process, one rectifying Column and auxiliary equipment thereof can be saved, the energy consumption is saved by 15%, and the investment and the cost are correspondingly reduced. The specific operation process comprises the steps of enabling an isopropanol solution to enter a common rectification section from a position located at the top of a partition plate, adding cyclohexane or other entrainer and the isopropanol solution to perform azeotropic rectification at a position close to the top of an upper section of a rectification tower, changing the azeotropic composition of an original isopropanol-water binary system, finally forming a system consisting of two different phase areas of isopropanol-water, enabling the isopropanol solution (the isopropanol content is greater than that of an azeotropic component) in a second phase area to enter a dehydration side (one side of the partition plate) section for rectification, obtaining an isopropanol product from the bottom of the dehydration side tower, enabling the isopropanol solution (the water content is greater than that of the azeotropic component) in a first phase area to enter the other side of the partition plate, namely a side line rectification section, obtaining water from the bottom of the tower, distilling the top of a bulkhead rectification tower to obtain a cyclohexane-isopropanol-water ternary azeotropic system, heating and supplementing cyclohexane, and forming cyclohexane in a phase splitter as the entrainer to return to the bulkhead rectification tower for recycling, and the water with the heaviest component obtained from the phase separator is returned to the side rectifying section as reflux, thereby realizing the dividing wall column rectifying process. Compared with the conventional two-tower azeotropic distillation, the method only saves energy consumption, investment and cost, but has quite large use and circulating consumption as a cyclohexane entrainer, and the purity of an isopropanol product is influenced and cannot reach more than 99.9 percent because an isopropanol-water binary system is added into a third component.
The existing separation technology such as molecular sieve membrane or pervaporation membrane utilizes the characteristic that the separation technology has selective separation due to the difference of osmotic pressure in an isopropanol-water binary azeotropic system, can effectively overcome the obstacle of azeotropic point, and is widely applied to various azeotropic systems such as ethanol, isopropanol, glycol and the like. However, the existing techniques such as molecular sieve membrane separation are often combined with conventional rectification in the process of separating or purifying isopropanol solution, for example, an independent molecular sieve membrane separation system is arranged in the middle of two-tower conventional rectification, and is not integrated in the process flow, so that the equipment has poor multi-stability and high investment and production cost. In addition, the molecular sieve membrane is also often used directly in the process of isopropanol solution skipping azeotropic point and isopropanol refining, thus a rectifying tower for conventional rectification in the phase II region of an isopropanol-water binary system can be saved. However, due to the limited amount of molecular sieve membrane permeation, when the product isopropanol with purity of 99.9% is obtained by entering the membrane separation system from the stream with high water content and approximate azeotropic composition, the circulation amount and separation number of the membrane separation system are greatly increased, which leads to the greatly increased investment and cost of the whole system. Therefore, the production of a high-purity isopropyl alcohol product from an aqueous isopropyl alcohol solution is rarely carried out in the actual industry by a combined process of one conventional rectification column and a multistage membrane separator.
Disclosure of Invention
The invention provides a partition tower type isopropanol solution molecular sieve membrane distillation separation and purification method, which utilizes the osmotic selectivity of a molecular sieve membrane, arranges a molecular sieve membrane separator at a public distillation section of a partition azeotropic distillation tower, combines the selectivity of membrane separation with the conventional distillation of an isopropanol-water binary system in a two-phase region divided by a partition plate, thereby forming a membrane separation and the conventional distillation separation in the two-phase region coupled in the molecular sieve membrane distillation tower, not only can stride over the azeotropic point of the isopropanol-water binary system, but also can effectively change the multi-tower combination form of the conventional molecular sieve membrane and the distillation, save investment, energy consumption and cost, simultaneously avoid introducing a third component (entrainer) of partition distillation into the system, thereby realizing the production of isopropanol products with low azeotropic consumption, low azeotropic cost, high purity and high yield (the purity is more than or equal to 99.9-99.99 percent), w/w), overcomes the defects of high energy consumption, low product purity, unstable operation, high investment and the like of the prior method for preparing isopropanol by azeotropic distillation of a partition tower and rectification of a molecular sieve membrane. Therefore, the invention adopts the following technical scheme:
a bulkhead tower type isopropanol solution molecular sieve membrane rectification separation and purification method is characterized in that a hollow clapboard used as a permeation side permeation water permeable channel of a molecular sieve membrane is arranged in a conventional rectification tower, the conventional rectification tower is divided into the left side and the right side, one side of the conventional rectification tower is a dehydration section for gas-liquid separation of an isopropanol-water binary system I phase region, the other side of the conventional rectification tower is an isopropanol refining section for gas-liquid separation of an isopropanol-water binary system II phase region, permeation water flows out of the bottom of the hollow clapboard, two primary molecular sieve membrane separators (A and B) which are connected in parallel are arranged between the top of the hollow clapboard and the top of the conventional rectification tower, a feed inlet of one membrane separator (A) is positioned on one side of the dehydration section, a feed inlet of the other membrane separator (B) is positioned on one side of the isopropanol refining section, and the front ends of the feed inlets of the two membrane separators are respectively provided with a overheating coil pipe for heating, the outlet positions of the material flows on the permeation side and the non-permeation side of the two membrane separators are the same, the material flow (water) outlet on the permeation side is connected with a hollow clapboard channel, the outlet position of the gas flow on the non-permeation side is positioned at the top of the membrane separator and is also the top of a partition wall tower type molecular sieve membrane rectification tower, an outlet pipeline of the material flow (water) outlet is connected with the inlet end of a superheater in front of the material flow inlet end of the membrane separator A, and is also connected with a condenser or a gas-liquid equilibrium separator which is independent of the partition wall tower type molecular sieve membrane rectification tower, so that the partition wall tower type molecular sieve membrane rectification separation and purification process is formed, specifically, an Isopropanol (IPA) solution is an aqueous solution with the isopropanol content of 20-60% (mass ratio, w/w, the same below), the temperature is 20-60 ℃, the pressure is normal pressure or low pressure, and the Isopropanol (IPA) solution is used as a raw material and enters the middle position on one side (left side) of a dehydration section of the tower type adsorption rectification tower type to perform conventional rectification in a phase I region of an isopropanol/water binary system, distilling water and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters at the bottom of a dehydration section, discharging the distillate out of a system for treatment, heating the distillate at the upper part of the dehydration section to 120-130 ℃ at a temperature of 75-85 ℃ and a pressure of 0.1-0.3 MPa, wherein the content of isopropanol generated at the upper part of the dehydration section is slightly lower than that of gas phase distillate consisting of isopropanol/water azeotrope (87.5% of isopropanol and 17.5% of water at normal pressure), feeding the distillate into a molecular sieve membrane separator (A) for membrane separation, discharging permeate (water) from a permeation side, performing heat exchange and vacuum pumping condensation through a hollow partition plate channel to form a liquid side stream water discharge system, returning part of the non-permeate gas consisting of 88-90% of isopropanol and 10-12% of water from a non-permeate discharge side to an inlet of the overheating coil positioned at the dehydration section side or the isopropanol refining section side, feeding the permeate into the membrane separator (A) or the membrane separator (B) to adjust the permeation quantity and the water permeation pressure in the membrane separator, a part of liquid formed by a condenser or a gas-liquid equilibrium separator independent of a bulkhead tower type molecular sieve membrane rectifying tower enters from the middle of the section as the feeding material of an isopropanol refining section after heat exchange, is subjected to conventional rectification in a phase II area of an isopropanol/water binary system, is distilled at the bottom of the isopropanol refining section to output an isopropanol product with the purity of more than or equal to 99.9 percent, generates a gas phase distillate with the isopropanol content slightly higher than that of an isopropanol/water azeotrope at the top of the gas phase distillate, enters a molecular sieve membrane separator (B) after passing through a thermal coil, flows out a permeate (water) from a permeation side, forms a liquid water discharge system after heat exchange and vacuum pumping condensation through a hollow partition channel, flows out a non-permeate gas with the components of 90-92 percent of isopropanol and 8-10 percent of water from a non-permeate side, and all enters the condenser or the gas-liquid equilibrium separator independent of the bulkhead tower type molecular sieve membrane rectifying tower, the formed liquid enters from the middle part of the isopropanol refining section as the feeding material of the isopropanol refining section after heat exchange, and is subjected to conventional rectification in a phase II area of an isopropanol/water binary system, and the isopropanol is further recovered, so that the yield of the isopropanol product is close to 100 percent.
Furthermore, the molecular sieve membrane separator is composed of a circular membrane tube which takes ceramic with multiple channels as a support body and is coated with selective materials including 3A, 4A, 5A, Carbon Nano Tubes (CNTs) or Carbon Molecular Sieves (CMS), or a plate-frame membrane and a membrane component which comprises a sealing member, a fixing member and a flange pipeline, and the molecular sieve membrane separator is composed of internal pressure type or external pressure type feeding, cross flow or vertical flow, preferably, the circular tube of the molecular sieve membrane with the multiple channels and internal pressure type cross flow 3A/4A/5A and the corresponding membrane component.
Furthermore, the membrane components or membrane materials of the two molecular sieve membrane separators (A and B) are different in selection, the positions of the hollow partition plates are different, and the radius of a dehydration section is larger than that of an isopropanol refining section.
Furthermore, the middle part and the lower part of the dehydration section side of the hollow partition plate are respectively provided with a through hole, so that water permeating from the permeation side of the molecular sieve membrane separator contains a small amount of isopropanol, the water is not directly discharged out of the system from the bottom of the hollow partition plate, but returns to the dehydration section to further recover the isopropanol, wherein the permeation water with low isopropanol content flows into the dehydration section from the through holes at the lower part, and the permeation water with high isopropanol content flows into the dehydration section from the through holes at the middle part.
Furthermore, the two molecular sieve membrane separators (A and B) are replaced by a pervaporation membrane separator for liquid-phase feeding and gas-phase permeation discharge, wherein the content of isopropanol generated at the upper part of the conventional rectification of a dividing wall tower type pervaporation membrane rectification dehydration section is slightly lower than that of a gas-phase distillate consisting of isopropanol/water azeotrope, the gas-phase distillate enters an independent external condenser or a gas-liquid equilibrium separator, the formed liquid enters the pervaporation membrane separator for pervaporation from the inlet end of the pervaporation membrane separator positioned at the dehydration section side, the permeated water liquid from the permeation side flows into a hollow partition plate channel and is vacuumized and cooled from the bottom of the hollow partition plate channel to be discharged out of a system, the non-permeated liquid flows out of the non-permeation side, the component of the non-permeated liquid is slightly higher than that of an isopropanol-water binary azeotropic system, the liquid directly enters a feed port positioned at the isopropanol rectification section for conventional rectification of the isopropanol-water binary system in a phase II, the isopropanol product flows out from the bottom of the isopropanol refining section, the gas phase distillate slightly higher than the isopropanol-water binary azeotropic system flows out from the upper part of the isopropanol refining section, and is mixed with the gas phase distillate generated at the upper part of the dehydration section in the conventional rectification and slightly lower than the isopropanol-water azeotrope to return to an independent external condenser or gas-liquid equilibrium separator, and the noncondensable gas escaped from the condenser or the gas-liquid equilibrium separator enters the dehydration section from the position close to the upper part of the dehydration section for further dehydration, or enters the dehydration section from the position close to the upper part of the isopropanol refining section for further recovery of the isopropanol.
Furthermore, the membrane material in the pervaporation membrane separator for liquid phase feeding and gas phase permeation discharging mainly comprises a plate-frame type membrane component, a modified sodium alginate membrane, a chitosan membrane, a sodium alginate and zeolite composite membrane material, a hollow fiber membrane component and a polymer membrane material.
Compared with the prior art, the invention has the beneficial effects that:
(1) the molecular sieve membrane separation has the selective permeation of water to achieve the purpose of skipping the azeotropic point when the isopropanol-water azeotropic point is used, the molecular sieve membrane or permeation gasification membrane separation and the isopropanol-water binary separation system process of the bulkhead tower type azeotropic distillation are coupled into the bulkhead tower type molecular sieve membrane distillation separation process, the characteristic of simple equipment process of the bulkhead tower type azeotropic distillation is fully utilized, the entrainer of the bulkhead tower type azeotropic distillation is saved, the investment and operation cost of the molecular sieve membrane separation and distillation combined process are greatly reduced, and the high-purity isopropanol product is obtained at the same time.
(2) The invention can install membrane separators composed of various membrane components and membrane materials on the upper part of a bulkhead tower type rectifying tower, and comprises a molecular sieve membrane separator composed of a gas-phase feeding liquid-phase permeation discharging 3A/4A/5A molecular sieve, a carbon molecular sieve and carbon nano tube membrane material and a multi-channel circular tube or plate-frame type component, a plate-frame type or hollow fiber permeation gasification membrane for liquid-phase feeding gas-phase permeation discharging, and the like.
(3) The invention realizes the control of the whole molecular sieve membrane rectification process by adjusting the proportion of non-permeating gas flowing out from the non-permeating sides of the molecular sieve membrane separators (A and B) to return to the respective membrane separators and the proportion of non-permeating gas flowing out from the non-permeating sides of the molecular sieve membrane separators to be used as feed of an isopropanol rectification section, so that the conventional rectification in a dehydration section and the isopropanol rectification section is highly coupled with the separation of the molecular sieve membrane, and the optimal operation is achieved.
(4) The invention realizes the adjustment of the proportion of water on the permeation side returning to the conventional rectification of the dehydration section by respectively arranging the through holes at the middle part and the lower part of the dehydration section side of the hollow partition plate, can be used as the reflux of the conventional rectification of the dehydration section, and can also solve the problem of fluctuation of the concentration of the isopropanol in the permeation water from the permeation side of the molecular sieve membrane separator, thereby further improving the yield of the isopropanol and improving the discharge of wastewater containing organic matters.
(5) Compared with the traditional separation wall tower type azeotropic distillation and membrane separation and conventional distillation combined process, the invention can greatly reduce equipment investment, device floor area, energy consumption and production cost, and is an innovative and efficient molecular sieve membrane distillation process.
Drawings
FIG. 1 is a schematic flow chart of example 1.
FIG. 2 is a schematic flow chart of example 2.
FIG. 3 is a schematic flow chart of example 3.
Detailed Description
In order to make those skilled in the art better understand the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention.
Example 1
As shown in figure 1, a molecular sieve distillation separation and purification method of a bulkhead tower type isopropanol solution, wherein an Isopropanol (IPA) solution is an aqueous solution with 20-60% (mass ratio, w/w, the same below), the temperature is 20-60 ℃, the pressure is normal pressure or low pressure, the aqueous solution enters from the middle position of one side (left side) of a dehydration section of a bulkhead tower type molecular sieve membrane distillation tower as a raw material and is subjected to conventional distillation in a phase I area of an isopropanol/water binary system, water and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters are distilled off from the bottom of the dehydration section, the water and other trace heavy component impurities are discharged out of a system for treatment, the content of the isopropanol generated at the upper part of the dehydration section is slightly lower than that of a gas phase distillate composed of an isopropanol/water azeotrope (87.5% of isopropanol and 17.5% of water under normal pressure), the temperature is 75-85 ℃, and the pressure is 0.1-0.3 MPa, heating to 120-130 ℃ by a superheating coil pipe, entering a first-stage molecular sieve separator (A) with 4A as a membrane material and a three-channel circular membrane pipe as a membrane component for membrane separation, flowing out permeate (water) from a permeation side, performing heat exchange and vacuumizing condensation by a hollow partition plate channel to form a liquid water discharge system, returning 20% of non-permeation gas with components of 88-90% of isopropanol and 10-12% of water from a non-permeation side to an inlet of the superheating coil pipe positioned on the isopropanol refining section side, entering the membrane separator (A) or a first-stage molecular sieve membrane separator (B) with 4A/5A as a membrane material and a three-channel circular membrane pipe as a membrane component for regulating the permeation quantity and water permeation pressure in the membrane separator, passing 80% of liquid formed by a condenser independent of a bulkhead tower type molecular sieve membrane rectifying tower, performing heat exchange, feeding as a feed of an isopropanol refining section, entering the middle of the section from the middle of the section, and performing conventional refining in a phase II area of the isopropanol/water binary system, distilling out isopropanol product with purity more than or equal to 99.9% at the bottom of the isopropanol refining section and outputting, the method comprises the following steps of (1) enabling a gas phase distillate generated at the top of the distillation column to have isopropanol content slightly higher than that of an isopropanol/water azeotrope to enter a molecular sieve membrane separator (B) after passing through a hot coil, enabling a permeate (water) to flow out from a permeation side, carrying out heat exchange and vacuumizing condensation through a hollow partition plate channel to form a liquid water discharge system, enabling non-permeation gas with components of 90-92% of isopropanol and 8-10% of water to flow out from a non-permeation side, enabling the non-permeation gas to completely enter a condenser or a gas-liquid equilibrium separator independent of a bulkhead tower type molecular sieve membrane rectifying tower, enabling the formed liquid to enter the middle of an isopropanol refining section as a feed after heat exchange, carrying out conventional rectification in a phase II area of an isopropanol/water binary system, and further recovering and recycling the isopropanol, wherein the yield of an isopropanol product is close to 100%.
Example 2
As shown in fig. 2, on the basis of embodiment 1, a through hole is respectively arranged in the middle and the lower part (between a feed inlet and a water outlet at the bottom) of the dewatering section side of the hollow partition board, when the content of isopropanol in water permeated in the early stage of the molecular sieve membrane separator is low, the through hole in the middle is opened to enter the conventional rectification of the dewatering section, the through hole at the lower part and the outlet of effluent at the bottom of the hollow partition board are both in a closed state, when the content of isopropanol in water permeated in the later stage of the molecular sieve membrane separator is high, the through hole at the lower part is opened to enter the conventional rectification of the dewatering section, and the through hole at the upper part and the outlet of effluent at the bottom of the hollow partition board are both in a closed state.
Example 3
As shown in figure 3, on the basis of the embodiment 1, two molecular sieve membrane separators (A and B) are replaced by a pervaporation membrane separator which is fed in liquid phase and discharged in gas phase by permeation and consists of polyacrylonitrile as a material and hollow fibers as a membrane component, at the moment, a gas phase distillate which is generated at the upper part of the conventional rectification of a dividing wall tower type pervaporation membrane rectification dehydration section and has the isopropanol content slightly lower than that of an isopropanol/water azeotrope enters an independent external condenser or a gas-liquid equilibrium separator to form liquid with the temperature of 60-120 ℃, enters the pervaporation membrane separator for pervaporation from the inlet end of the pervaporation membrane separator positioned at the side of the dehydration section, the water permeated from the pervaporation side flows into a hollow partition channel and is vacuumized and cooled from the bottom of the hollow partition channel to be discharged out of a system, the non-permeable liquid flows out from the non-permeable side, and the component of the liquid slightly higher than that of the isopropanol-water azeotropic system, directly enters a feed inlet positioned at an isopropanol refining section to carry out conventional rectification of an isopropanol-water binary system in a phase II area, an isopropanol product flows out from the bottom of the isopropanol refining section, a gas phase distillate slightly higher than the isopropanol-water binary azeotropic system flows out from the upper part, and is mixed with the gas phase distillate generated at the upper part of the conventional rectification of a dehydration section and having the isopropanol content slightly lower than the isopropanol-water azeotropic system and then returns to an independent external condenser or a gas-liquid equilibrium separator, non-condensable gas escaped from the condenser or the gas-liquid equilibrium separator enters the dehydration section from a position of the dehydration section close to the upper part for further dehydration, and the conventional rectification operation of the dehydration section is adjusted.
It should be apparent that the above-described embodiments are only some, but not all, of the embodiments of the present invention. All other embodiments and structural changes that can be made by those skilled in the art without inventive effort based on the embodiments described in the present invention or based on the teaching of the present invention, all technical solutions that are the same or similar to the present invention, are within the scope of the present invention.
Claims (6)
1. A bulkhead tower type isopropanol solution molecular sieve membrane rectification separation and purification method is characterized in that a hollow clapboard used as a permeation side permeation water permeable channel of a molecular sieve membrane is arranged in a conventional rectification tower, the conventional rectification tower is divided into the left side and the right side, one side of the conventional rectification tower is a dehydration section for gas-liquid separation of an isopropanol-water binary system I phase region, the other side of the conventional rectification tower is an isopropanol refining section for gas-liquid separation of an isopropanol-water binary system II phase region, permeation water flows out of the bottom of the hollow clapboard, two primary molecular sieve membrane separators (A and B) which are connected in parallel are arranged between the top of the hollow clapboard and the top of the conventional rectification tower, a feed inlet of one membrane separator (A) is positioned on one side of the dehydration section, a feed inlet of the other membrane separator (B) is positioned on one side of the isopropanol refining section, and the front ends of the feed inlets of the two membrane separators are respectively provided with a overheating coil pipe for heating, the outlet positions of the material flows on the permeation side and the non-permeation side of the two membrane separators are the same, the material flow (water) outlet on the permeation side is connected with a hollow clapboard channel, the outlet position of the gas flow on the non-permeation side is positioned at the top of the membrane separator and is also the top of a partition wall tower type molecular sieve membrane rectification tower, an outlet pipeline of the material flow (water) outlet is connected with the inlet end of a superheater in front of the material flow inlet end of the membrane separator A, and is also connected with a condenser or a gas-liquid equilibrium separator which is independent of the partition wall tower type molecular sieve membrane rectification tower, so that the partition wall tower type molecular sieve membrane rectification separation and purification process is formed, specifically, an Isopropanol (IPA) solution is an aqueous solution with the isopropanol content of 20-60% (mass ratio, w/w, the same below), the temperature is 20-60 ℃, the pressure is normal pressure or low pressure, and the Isopropanol (IPA) solution is used as a raw material and enters the middle position on one side (left side) of a dehydration section of the tower type adsorption rectification tower type to perform conventional rectification in a phase I region of an isopropanol/water binary system, distilling water and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters at the bottom of a dehydration section, discharging the distillate out of a system for treatment, heating the distillate at the upper part of the dehydration section to 120-130 ℃ at a temperature of 75-85 ℃ and a pressure of 0.1-0.3 MPa, wherein the content of isopropanol generated at the upper part of the dehydration section is slightly lower than that of gas phase distillate consisting of isopropanol/water azeotrope (87.5% of isopropanol and 17.5% of water at normal pressure), feeding the distillate into a molecular sieve membrane separator (A) for membrane separation, discharging permeate (water) from a permeation side, performing heat exchange and vacuum pumping condensation through a hollow partition plate channel to form a liquid side stream water discharge system, returning part of the non-permeate gas consisting of 88-90% of isopropanol and 10-12% of water from a non-permeate discharge side to an inlet of the overheating coil positioned at the dehydration section side or the isopropanol refining section side, feeding the permeate into the membrane separator (A) or the membrane separator (B) to adjust the permeation quantity and the water permeation pressure in the membrane separator, a part of liquid formed by a condenser or a gas-liquid equilibrium separator independent of a bulkhead tower type molecular sieve membrane rectifying tower enters from the middle of the section as the feeding material of an isopropanol refining section after heat exchange, is subjected to conventional rectification in a phase II area of an isopropanol/water binary system, is distilled at the bottom of the isopropanol refining section to output an isopropanol product with the purity of more than or equal to 99.9 percent, generates a gas phase distillate with the isopropanol content slightly higher than that of an isopropanol/water azeotrope at the top of the gas phase distillate, enters a molecular sieve membrane separator (B) after passing through a thermal coil, flows out a permeate (water) from a permeation side, forms a liquid water discharge system after heat exchange and vacuum pumping condensation through a hollow partition channel, flows out a non-permeate gas with the components of 90-92 percent of isopropanol and 8-10 percent of water from a non-permeate side, and all enters the condenser or the gas-liquid equilibrium separator independent of the bulkhead tower type molecular sieve membrane rectifying tower, and the formed liquid enters from the middle part of the isopropanol refining section as a feed of the isopropanol refining section after heat exchange, and is subjected to conventional rectification in a phase II area of an isopropanol/water binary system, and the isopropanol is further recovered, so that the yield of the isopropanol product is close to 100% 1.
2. The partition wall tower type isopropanol solution molecular sieve membrane rectification separation and purification method as claimed in claim 1, characterized in that the molecular sieve membrane separator is composed of a ceramic support with multiple channels and coated with a circular membrane tube comprising 3A, 4A, 5A, Carbon Nanotubes (CNTs) or Carbon Molecular Sieve (CMS) selective materials, or a plate-frame membrane and a membrane component comprising a sealing member, a fixing member and a flange pipeline, and the molecular sieve membrane separator 2 is composed of a feeding material with internal pressure or external pressure, a cross flow or a vertical flow, preferably, a multi-channel internal pressure cross flow 3A/4A/5A molecular sieve membrane circular tube and a corresponding membrane component.
3. The method for separating and purifying isopropanol solution by molecular sieve membrane distillation in dividing wall tower form according to claim 1, wherein the membrane components or membrane materials of the two molecular sieve membrane separators (A and B) are different, the positions of the hollow partition plates are different, and the radius of the dehydration section is larger than the radius 3 of the isopropanol refining section.
4. The method as claimed in claim 1, wherein a through hole is respectively formed in the middle and lower parts of the dehydration section side of the hollow partition plate, so that the water permeating from the permeation side of the molecular sieve membrane separator contains a small amount of isopropanol, and is returned to the dehydration section for further recovery of isopropanol without being directly discharged from the system at the bottom of the hollow partition plate, wherein the permeate water with low isopropanol content flows into the dehydration section from the through hole in the lower part, and the permeate water with high isopropanol content flows into the dehydration section 4 from the through hole in the middle part.
5. The method for fractionating, separating and purifying an isopropanol solution by a dividing wall tower type molecular sieve membrane distillation as claimed in claim 1, wherein the two molecular sieve membrane separators (A and B) are replaced by a pervaporation membrane separator for liquid phase feeding and gas phase permeation discharging, wherein the upper part of the normal distillation of the dividing wall tower type pervaporation membrane distillation dehydration section produces a gas phase distillate with slightly lower isopropanol content than that of an isopropanol/water azeotrope, the gas phase distillate enters an externally arranged condenser or a gas-liquid equilibrium separator, the formed liquid enters the pervaporation membrane separator for pervaporation from the inlet end of the pervaporation membrane separator at the dehydration section side, the permeated water liquid from the pervaporation side flows into a hollow partition channel and is vacuumized and cooled from the bottom of the hollow partition channel to be discharged from the non-permeation side, and the component of the liquid is slightly higher than that of the isopropanol-water binary azeotropic system, directly enters a feed inlet positioned at an isopropanol refining section to carry out conventional rectification of an isopropanol-water binary system in a phase II area, an isopropanol product flows out from the bottom of the isopropanol refining section, a gas phase distillate slightly higher than the isopropanol-water binary azeotropic system flows out from the upper part, and is mixed with a gas phase distillate generated at the upper part of the conventional rectification of a dehydration section and having the isopropanol content slightly lower than that of the isopropanol-water azeotrope and then returns to an independent external condenser or a gas-liquid equilibrium separator, and non-condensable gas escaping from the condenser or the gas-liquid equilibrium separator enters the dehydration section from a position close to the upper part of the dehydration section to be further dehydrated, or enters the dehydration section from a position close to the upper part of the isopropanol refining section to be further recycled to obtain isopropanol 5.
6. The partition tower type isopropanol solution molecular sieve membrane rectification separation and purification method of claim 4, wherein the membrane material in a pervaporation membrane separator for liquid phase feeding and gas phase permeation discharging mainly comprises a plate-frame type membrane component, a modified sodium alginate, a chitosan membrane, a sodium alginate and zeolite composite membrane material, a hollow fiber membrane component and a polymer membrane material 6.
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Inventor after: Wang Lanhai Inventor after: Chen Yun Inventor after: Tang Jincai Inventor after: Zhong Yuming Inventor after: Cai Yueming Inventor before: Wang Lanhai Inventor before: Chen Yun Inventor before: Tang Jincai Inventor before: Zhong Yuming Inventor before: Cai Yueming |