CN114456039B - Separation wall tower type isopropanol solution molecular sieve membrane rectification separation and purification method - Google Patents
Separation wall tower type isopropanol solution molecular sieve membrane rectification separation and purification method Download PDFInfo
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- CN114456039B CN114456039B CN202111504280.6A CN202111504280A CN114456039B CN 114456039 B CN114456039 B CN 114456039B CN 202111504280 A CN202111504280 A CN 202111504280A CN 114456039 B CN114456039 B CN 114456039B
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- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 title claims abstract description 351
- 239000012528 membrane Substances 0.000 title claims abstract description 161
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 76
- 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 76
- 238000000926 separation method Methods 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000000746 purification Methods 0.000 title claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 83
- 238000005192 partition Methods 0.000 claims abstract description 59
- 230000018044 dehydration Effects 0.000 claims abstract description 53
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 53
- 239000007788 liquid Substances 0.000 claims abstract description 45
- 239000012466 permeate Substances 0.000 claims abstract description 39
- XTUSEBKMEQERQV-UHFFFAOYSA-N propan-2-ol;hydrate Chemical compound O.CC(C)O XTUSEBKMEQERQV-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000007670 refining Methods 0.000 claims abstract description 26
- 229910002056 binary alloy Inorganic materials 0.000 claims abstract description 25
- 230000003204 osmotic effect Effects 0.000 claims abstract description 22
- 239000000047 product Substances 0.000 claims abstract description 21
- 238000009833 condensation Methods 0.000 claims abstract description 8
- 230000005494 condensation Effects 0.000 claims abstract description 8
- 239000012071 phase Substances 0.000 claims description 54
- 239000000243 solution Substances 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 23
- 238000004821 distillation Methods 0.000 claims description 13
- 238000002309 gasification Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- 238000007599 discharging Methods 0.000 claims description 9
- 239000007791 liquid phase Substances 0.000 claims description 7
- 238000001179 sorption measurement Methods 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 5
- 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
- 229910001385 heavy metal Inorganic materials 0.000 claims description 4
- 239000012510 hollow fiber Substances 0.000 claims description 4
- 230000001105 regulatory effect Effects 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
- 238000010438 heat treatment Methods 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 238000005373 pervaporation Methods 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
- 229910021393 carbon nanotube Inorganic materials 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
- 238000013021 overheating Methods 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
- 238000010533 azeotropic distillation Methods 0.000 description 9
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 238000005265 energy consumption Methods 0.000 description 6
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 5
- 238000009835 boiling Methods 0.000 description 4
- 238000005516 engineering 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
- 238000000895 extractive distillation Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000000149 penetrating effect Effects 0.000 description 2
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000012153 distilled water Substances 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
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- -1 lipid alcohols Chemical class 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000026676 system process Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
-
- 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 separation wall tower type isopropyl alcohol solution molecular sieve membrane rectification separation and purification method, isopropyl alcohol water solution enters the middle part of a dehydration section which is separated into two sides by a hollow partition board in a rectification tower to carry out isopropyl alcohol-water binary system I phase region rectification, water is discharged from the bottom, distilled gas enters a molecular sieve membrane separator A, permeate flows out from the permeate side and forms liquid water after heat exchange and vacuumizing condensation through a hollow partition board channel to be discharged, gas flowing out from the non-permeate side is partially returned to a superheating coil pipe inlet to enter the membrane separator A/B to regulate the permeation quantity and water osmotic pressure in the membrane separator, liquid formed by a condenser enters an isopropyl alcohol refining section to carry out rectification in a II phase region, isopropyl alcohol product with purity of more than or equal to 99.9% is distilled out from the bottom, gas phase distillate generated from the top enters a molecular sieve membrane separator B, permeate flows out from the permeate side and forms liquid water after heat exchange and vacuumizing condensation through the hollow partition board channel, gas flowing out from the non-permeate side is completely enters the condenser to form liquid water after being returned to the II phase region rectification, and isopropyl alcohol product yield 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 in particular relates to a separation wall tower type isopropanol solution molecular sieve membrane rectification separation and purification method.
Background
The concentration of the crude isopropyl alcohol aqueous solution (hereinafter referred to as "isopropyl alcohol solution") obtained by the hydration method is about 20-60% (w/w), the water concentration is 40-80%, other small amount of impurities comprise organic matters such as lipid alcohols and trace amount of water-soluble heavy metal impurities, and further dehydration and purification are needed to obtain isopropyl alcohol products with higher purity, such as purity of 99.9% (w/w) or more. However, since isopropanol and water can form an azeotrope, for example, an azeotropic composition under normal pressure is a binary azeotropic system with an isopropanol concentration of 87.4%, water of 12.6%, an azeotropic temperature of 80.31 ℃, a self boiling point of 82.45 ℃ under normal pressure, water of 100 ℃ and an azeotrope formed by an isopropanol-water solution as the lowest boiling point. Therefore, to obtain isopropyl alcohol of higher purity, general distillation cannot be realized, and special separation methods such as constant (co) boiling distillation with constant boiling agent (benzene, etc.), azeotropic distillation with energy-saving dividing wall column, extractive distillation with extractant (ethylene glycol, etc.), extractive distillation with salt addition, extractive distillation with gap, pressure swing distillation, membrane distillation, etc. must be adopted. Besides special rectification method, the method also comprises pervaporation membrane, membrane contactor, temperature Swing Adsorption (TSA), adsorption rectification combined by adsorption and rectification, and the like, and is used for separating and purifying isopropanol solution, wherein the adsorption rectification is a brand new isopropanol dehydration process.
The existing partition tower azeotropic distillation (DIVIDING WALL Column, DWC for short) method is to arrange a vertical partition in a common distillation tower, which is equivalent to a Petlyuk tower (thermocouple distillation or side stripping) in thermodynamics, and the addition of the partition realizes the functions of two towers, namely 3 pure component products (isopropanol, water and cyclohexane entrainer) can be obtained by only one distillation tower, compared with the conventional two-tower azeotropic distillation technology, one distillation tower and auxiliary equipment thereof can be saved, the energy consumption is saved by 15 percent, and the investment and the cost are correspondingly reduced. The method comprises the specific operation procedures that an isopropyl alcohol solution enters a public rectifying section from a position positioned at the top of a baffle, cyclohexane or other entrainer and the isopropyl alcohol solution are added at a position, close to the top, of the upper section of the rectifying tower to carry out azeotropic distillation, so that the azeotropic composition of an original isopropyl alcohol-water binary system is changed, a system consisting of two different phase areas of isopropyl alcohol and water is finally formed, the isopropyl alcohol solution (the isopropyl alcohol content is greater than the azeotropic composition) in a second phase area enters a dehydration side (one side of the baffle) section for rectification, an isopropyl alcohol product is obtained from the bottom of the dehydration side, the isopropyl alcohol solution (the water content is greater than the azeotropic composition) in a first phase area enters the other side of the baffle, namely a side rectifying section, water is obtained from the bottom of the baffle, the cyclohexane-isopropyl alcohol-water ternary azeotropic system at the top of the baffle is heated and supplemented with cyclohexane, cyclohexane is formed in the phase separator to be recycled as the entrainer, and water of the most heavy composition is obtained from the phase separator and returns to the side rectifying section of the baffle, so that the partition rectifying process is realized. Compared with the conventional two-tower azeotropic distillation, the method only saves energy consumption, investment and cost, but the consumption and the circulating consumption of the method as the cyclohexane entrainer are quite large, and the purity of the isopropanol product is influenced and cannot reach more than 99.9 percent due to the addition of the third component into the isopropanol-water binary system.
The existing separation technology of molecular sieve membrane or osmotic gasification membrane is to use the characteristic that the separation technology still has different osmotic pressure in an isopropyl alcohol-water binary azeotropic system and has selective separation, can effectively overcome the obstacle of azeotropic point, and is widely applied in various azeotropic systems such as ethanol, isopropyl alcohol, ethylene glycol and the like. However, the existing molecular sieve membrane separation technology is often combined with conventional rectification in the separation or purification process of 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 commonly and directly used in the process of skipping the azeotropic point of the isopropanol solution and refining the isopropanol, so that a rectifying tower for carrying out conventional rectification on an isopropanol-water binary system in a phase II area can be omitted. However, since the molecular sieve membrane has a limited permeation amount, when an isopropyl alcohol product with a purity of 99.9% is obtained by feeding a stream having a relatively high water content and close to azeotropic composition into a membrane separation system, the circulation amount and the separation stages of the membrane separation system are greatly increased, and the investment and cost of the whole system are also greatly increased. Therefore, the production of high purity isopropyl alcohol product from an aqueous isopropyl alcohol solution is rarely performed in the practical industry using a conventional rectification column plus multistage membrane separator combination process.
Disclosure of Invention
The invention provides a molecular sieve membrane rectifying separation and purification method of a partition wall tower type isopropyl alcohol solution, which utilizes the permeation selectivity of a molecular sieve membrane, and places a molecular sieve membrane separator in a public rectifying section of a partition wall azeotropic rectifying tower, wherein the selectivity of membrane separation is combined with the conventional rectification of an isopropyl alcohol-water binary system in a two-phase area separated by a partition plate, so that the membrane separation and the conventional rectification separation in the two-phase area are coupled in one molecular sieve membrane rectifying tower, the azeotropic point of the isopropyl alcohol-water binary system can be crossed, the multi-tower combined form of the conventional molecular sieve membrane and rectification can be effectively changed, the investment, the energy consumption and the cost are saved, and meanwhile, the introduction system of a third component (entrainer) of the partition wall azeotropic rectification is avoided, so that the low-energy consumption, low-cost and high-purity isopropyl alcohol product (the purity is more than or equal to 99.9-99%, and w/w) can be realized, and the defects of high energy consumption, low product purity, unstable operation, high investment and the like of the conventional partition wall tower azeotropic rectification and the molecular sieve membrane rectification isopropyl alcohol product are overcome. For this purpose, the invention adopts the following technical scheme:
A membrane rectifying separation and purification method for separating isopropanol solution by a membrane tower is characterized in that a hollow baffle serving as a permeation channel of a permeation side of a molecular sieve membrane is arranged in a conventional rectifying tower, the conventional rectifying tower is divided into a left side and a right side, one side is a dehydration section for gas-liquid separation of an I-phase region of an isopropanol-water binary system, the other side is an isopropanol refining section for gas-liquid separation of an II-phase region of the isopropanol-water binary system, permeate water flows out from the bottom of the hollow baffle, two parallel first-stage molecular sieve membrane separators (A and B) are arranged between the top of the hollow baffle and the top of the conventional rectifying tower, a feed inlet of one membrane separator (A) is positioned at one side of the dehydration section, a feed inlet of the other membrane separator (B) is positioned at one side of the isopropanol refining section, the front ends of the feed inlets of the two membrane separators are respectively provided with an overheating coil pipe for heating, the positions of the outlets of the permeate side and the non-permeate side material flows of the two membrane separators are the same, the outlet of the permeate side material flow (water) is connected with a hollow partition plate channel, the outlet of the non-permeate side material flow is positioned at the top of the membrane separator, also is the top of a partition wall tower type molecular sieve membrane rectifying tower, the outlet pipeline of the non-permeate side material flow is connected with the inlet end of a superheater in front of the inlet end of the material flow 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 rectifying tower, thereby forming the process of rectifying, separating and purifying the partition wall tower type molecular sieve membrane, specifically, the isopropyl alcohol (IPA) solution is an aqueous solution with the isopropyl alcohol content of 20-60% (mass ratio, w/w is the same as below), the temperature is 20-60 ℃ and the pressure is normal pressure or low pressure, the method is characterized in that raw materials enter from the middle position of one side (left side) of a dehydration section of a partition tower type adsorption rectifying tower and are subjected to conventional rectification in an I-phase region of an isopropyl alcohol/water binary system, water and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters are distilled out of the bottom of the dehydration section, the discharged system is used for treatment, the generated gas-phase distillate with the isopropyl alcohol content slightly lower than that of isopropyl alcohol/water azeotrope composition (87.5% isopropyl alcohol and 17.5% water under normal pressure) at the temperature of 75-85 ℃ and the pressure of 0.1-0.3 MPa is heated to 120-130 ℃ through a overheat coil and enters a molecular sieve membrane separator (A) for membrane separation, permeate (water) flows out of the permeation side and is subjected to heat exchange and vacuumizing condensation through a hollow partition plate channel to form a liquid water discharged system, the non-permeate gas with the components of 88-90% of isopropanol and 10-12% of water flows out from the non-permeate side, part of the non-permeate gas returns to an overheated coil inlet positioned at the dehydration section side or the isopropanol refining section side to enter a membrane separator (A) or a membrane separator (B) to adjust the permeation quantity and the water permeation pressure in the membrane separator, part of the non-permeate gas passes through a condenser or a gas-liquid equilibrium separator which is independent of a partition tower type molecular sieve membrane rectifying tower to form liquid, the liquid enters from the middle part of the section as the feeding of the isopropanol refining section after heat exchange and is subjected to conventional rectification in a phase II of an isopropanol/water binary system, an isopropanol product with the purity of more than or equal to 99.9% is distilled out at the bottom of the isopropanol refining section, a gas phase distillate with the isopropanol content slightly higher than that of an isopropanol/water azeotrope generated at the top of the non-permeate gas enters the molecular sieve membrane separator (B) after passing through a hot coil, and (3) flowing out of permeate (water) from the permeation side, performing heat exchange and vacuumizing condensation through a hollow partition plate channel to form a liquid water discharge system, and completely entering non-permeation gas with components of 90-92% isopropyl alcohol and 8-10% water from the non-permeation side into a condenser or a gas-liquid equilibrium separator which is independent of a partition wall tower type molecular sieve membrane rectifying tower, wherein the formed liquid enters from the middle part of the section as a feeding material of an isopropyl alcohol refining section after heat exchange and is subjected to conventional rectification in a II-phase region of an isopropyl alcohol/water binary system, so that the recovery of isopropyl alcohol is further recovered, and the yield of isopropyl alcohol products is close to 100%.
Furthermore, the molecular sieve membrane separator is composed of a ceramic with multiple channels as a support body and coated with a round membrane tube containing 3A or 4A or 5A or Carbon Nanotubes (CNTs) or Carbon Molecular Sieve (CMS) selective materials, or a plate-frame membrane and a membrane assembly containing sealing elements, fixing elements and flange pipelines, and is formed by feeding internal pressure or external pressure, cross flow or vertical flow, preferably, the molecular sieve membrane separator is composed of a multi-channel internal pressure cross flow 3A/4A/5A molecular sieve membrane round tube and corresponding membrane assemblies.
Furthermore, the membrane components or membrane materials of the two molecular sieve membrane separators (A and B) are different in selection, and the hollow partition plates are also different in arrangement positions, including the radius of the dehydration section being larger than that of the isopropanol refining section.
Furthermore, the middle part and the lower part of the dehydration section side of the hollow partition board are respectively provided with a through hole, so that the water permeated from the permeation side of the molecular sieve membrane separator contains a small amount of isopropanol, the water is not directly discharged from the bottom of the hollow partition board, but is returned to the dehydration section to further recover the isopropanol, wherein the permeate water with small isopropanol content flows into the dehydration section from the lower through holes, and the permeate water with large isopropanol content flows into the dehydration section from the middle through holes.
Furthermore, the two molecular sieve membrane separators (A and B) are replaced by one osmotic gasifying membrane separator for liquid phase feeding gas phase permeation discharging, wherein the component of the osmotic gasifying membrane separator is slightly higher than that of the conventional rectifying upper part of the partition tower type osmotic gasifying membrane rectifying dehydration section, the gas phase distillate which is slightly lower than that of the isopropyl alcohol/water binary system is produced, the gas phase distillate enters an independent external condenser or a gas-liquid equilibrium separator from the inlet end of the osmotic gasifying membrane separator at the dehydration section side for osmotic gasification, the water seepage liquid from the permeation side flows into a hollow partition plate channel and is pumped into a vacuum cooling discharging system from the bottom of the osmotic gasifying membrane separator, the non-osmotic liquid flows out from the non-osmotic side, the component of the non-osmotic liquid is slightly higher than that of the isopropyl alcohol-water binary azeotropic system, the conventional rectifying upper part is directly fed into the feed inlet of the isopropyl alcohol-water binary system in a phase II region, the isopropyl alcohol product flows out from the bottom of the isopropyl alcohol rectifying section, the gas phase distillate which is slightly higher than that of the isopropyl alcohol-water binary system is produced from the upper part, the gas phase distillate which is produced from the upper part and the conventional rectifying upper part of the osmotic membrane separator enters the osmotic membrane separator from the dehydration section, the gas phase distillate which is slightly higher than that of the isopropyl alcohol-water binary system is separated from the external condenser or is slightly lower than that of the gas phase distillate is separated from the upper part of the isopropyl alcohol-water binary system, and the gas phase distillate is further separated from the upper part or is more than the condensate section or is close to the dehydration equilibrium position of the evaporator, and is further separated from the upper part of the condensate phase separator.
Further, the membrane materials in the liquid-phase feeding gas-phase permeation discharging one permeation gasification membrane separator mainly comprise a plate-frame type membrane component, modified sodium alginate, 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 purpose of skipping the azeotropic point by selectively penetrating moisture when the isopropyl alcohol and water are in the azeotropic point, the molecular sieve membrane or the penetrating gasification membrane separation is coupled with the isopropyl alcohol and water binary separation system process of the partition tower type azeotropic distillation to form a partition tower type molecular sieve membrane distillation separation process, the characteristic of simple equipment process of the partition tower type azeotropic distillation is fully utilized, and the entrainer of the partition tower type azeotropic distillation is omitted, thereby greatly reducing the investment and operation cost of the molecular sieve membrane separation and distillation combined process and simultaneously obtaining the isopropyl alcohol product with high purity.
(2) The invention can install the membrane separator composed of various membrane components and membrane materials on the upper part of the partition tower type rectifying tower, and comprises a 3A/4A/5A molecular sieve for gas-phase feeding and liquid-phase permeation discharging, a molecular sieve membrane separator composed of carbon molecular sieve and carbon nano tube membrane materials and multi-channel circular tube or plate-frame components, a plate-frame or hollow fiber permeation gasification membrane for liquid-phase feeding and gas-phase permeation discharging, and the like.
(3) According to the invention, the control of the whole molecular sieve membrane rectification process is realized by adjusting the proportion of the non-permeable gas flowing out from the non-permeable sides of the molecular sieve membrane separators (A and B) to return to the respective membrane separators and the proportion of the non-permeable gas serving as the feed of the isopropyl alcohol refining section, so that the coupling between the conventional rectification and the molecular sieve membrane separation heights of the dehydration section and the isopropyl alcohol refining section is realized, and the optimal operation is achieved.
(4) The invention realizes the proportion of regulating the water at the permeation side to return to the conventional rectification of the dehydration section by arranging the through holes at the middle part and the lower part of the dehydration section side of the hollow partition board respectively, can be used as the reflux of the conventional rectification of the dehydration section, can also solve the problem of fluctuation of the concentration of isopropanol in the permeation water from the permeation side of the molecular sieve membrane separator, further improves the yield of isopropanol and improves the discharge of wastewater containing organic matters.
(5) Compared with the traditional bulkhead tower azeotropic distillation and membrane separation and conventional distillation combined process, the invention can greatly reduce equipment investment, device occupation area, energy consumption and production cost, and is a novel 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 enable those skilled in the art to better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Example 1
As shown in figure 1, the molecular sieve rectifying separation and purification method for the partition wall tower type isopropanol solution is characterized in that the Isopropanol (IPA) solution is an aqueous solution with the isopropanol content of 20-60% (mass ratio, w/w, the same applies hereinafter), 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 the partition wall tower type molecular sieve membrane rectifying tower as a raw material and is subjected to conventional rectification in an I phase zone of an isopropanol/water binary system, distilled water and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters are discharged from the bottom of the dehydration section and are treated by a discharge system, the isopropanol content 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% isopropanol and 17.5% water under normal pressure), heating to 120-130 ℃ at a temperature of 75-85 ℃ under a pressure of 0.1-0.3 MPa by a superheating coil, then entering a primary molecular sieve separator (A) with 4A as a membrane material and a three-way circular membrane tube as a membrane component for membrane separation, discharging permeate (water) from a permeate side, performing heat exchange and vacuumizing condensation by a hollow partition plate channel to form a liquid water discharge system, discharging a component of non-permeate side into non-permeate gas with 88-90% of isopropanol and 10-12% of water, returning 20% of the non-permeate gas to an inlet of the superheating coil at the isopropanol refining section side to enter the membrane separator (A) or regulating the permeation quantity and the water permeation pressure in the membrane separator by a primary molecular sieve membrane separator (B) with 4A/5A as a membrane material and a three-way circular membrane tube as a membrane component, and 80% of the liquid formed by a condenser independent of a partition plate tower type molecular sieve membrane rectifying tower, the gas phase distillate with the isopropyl alcohol content slightly higher than that of the isopropyl alcohol/water azeotrope generated at the top part is fed into a molecular sieve membrane separator (B) after passing through a hot coil, permeate (water) flows out from the permeation side, and is subjected to heat exchange and vacuumizing condensation through a hollow partition plate channel to form a liquid water discharge system, non-permeate gas with the components of 90-92% isopropyl alcohol and 8-10% water flows out from the non-permeation side, all the non-permeate gas enters a condenser or a gas-liquid equilibrium separator which is independent of a partition wall tower type molecular sieve membrane rectifying tower, the formed liquid enters from the middle part of the isopropyl alcohol refining section after passing through the heat exchange and is subjected to conventional rectification in the II phase region of the isopropyl alcohol/water binary system, and the yield of the isopropyl alcohol product is recovered and recovered to be close to 100%.
Example 2
As shown in fig. 2, on the basis of example 1, a through hole is respectively provided in the middle and lower parts of the dehydration section side of the hollow partition board (between the dehydration section feed inlet and the bottom water outlet), when the isopropanol content in the water permeated out from the front stage of the molecular sieve membrane separator is small, the through hole in the middle part is opened to enter the conventional rectification of the dehydration section, the through hole in the lower part and the outlet of the water flowing out from the bottom of the hollow partition board are both in a closed state, and when the isopropanol content in the water permeated out from the rear stage of the molecular sieve membrane separator is large, the through hole in the lower part is opened to enter the conventional rectification of the dehydration section, and the through hole in the upper part and the outlet of the water flowing out from the bottom of the hollow partition board are both in a closed state.
Example 3
As shown in FIG. 3, on the basis of example 1, two molecular sieve membrane separators (A and B) are replaced by a permeation and gasification membrane separator which is made of polyacrylonitrile as a material and hollow fibers as a membrane component and is used for liquid-phase feeding gas-phase permeation and discharge, at the moment, the gas-phase distillate which is produced at the upper part of the conventional rectification of a dividing wall tower type permeation and gasification membrane rectification dehydration section and has the isopropyl alcohol content slightly lower than that of isopropyl alcohol/water azeotrope enters an independent external condenser or a gas-liquid equilibrium separator, the temperature of the formed liquid is 60-120 ℃, the formed liquid enters the permeation and gasification membrane separator from the inlet end of the permeation and gasification membrane separator at the dehydration section side for permeation and gasification, the permeated water liquid from the permeation side flows into a hollow baffle channel, the bottom of the hollow baffle channel is vacuumized, cooled and discharged by a system, the non-permeated liquid flows out from the non-permeation side, the components of the method are slightly higher than the components of an isopropyl alcohol-water binary azeotropic system, the isopropyl alcohol product flows out from the bottom of the isopropyl alcohol refining section through the conventional rectification of the isopropyl alcohol-water binary system in a phase II region directly entering a feed inlet positioned in the isopropyl alcohol refining section, a gas phase distillate slightly higher than the components of the isopropyl alcohol-water binary azeotropic system flows out from the upper part of the isopropyl alcohol refining section, the gas phase distillate slightly lower than the components of the isopropyl alcohol-water binary azeotropic system generated by the conventional rectification of the dehydration section is mixed with the gas phase distillate slightly lower than the components of the isopropyl alcohol-water azeotrope, and then the mixture returns to an independent external condenser or a gas-liquid equilibrium separator, the noncondensable 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 for further dehydration, and the conventional rectification operation of the dehydration section is regulated.
It will be apparent that the embodiments described above are only some, but not all, of the embodiments of the present invention. All other embodiments, or structural changes made by those skilled in the art without inventive effort, based on the embodiments described herein, are intended to be within the scope of the invention, as long as the same or similar technical solutions as the invention are provided.
Claims (6)
1. A membrane rectifying separation and purification method for separating isopropanol solution by a partition tower is characterized in that a hollow partition plate is arranged in a conventional rectifying tower and is used as a permeation channel of a molecular sieve membrane on the permeation side, the conventional rectifying tower is divided into a dehydration section for gas-liquid separation of an I-phase region of an isopropanol-water binary system, a separation section for gas-liquid separation of an II-phase region of the isopropanol-water binary system is arranged on one side of the conventional rectifying tower, permeate water flows out of the bottom of the hollow partition plate, two parallel first-stage molecular sieve membrane separators A and B are arranged between the top of the hollow partition plate and the top of the conventional rectifying tower, a feed inlet of the first-stage molecular sieve 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, an overheating coil is respectively arranged at the front ends of the two membrane feed inlets for heating, the permeate side and the non-permeate side of the two membrane separators are the same, the permeate side material flow, namely the water outlet, is connected with the hollow partition board channel, the outlet of the non-permeate side air flow is positioned at the top of the membrane separator, also is positioned at the top of the partition wall tower type molecular sieve membrane rectifying tower, the outlet pipeline of the non-permeate side air flow is connected with the inlet end of the superheater in front of the inlet end of the material flow 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 rectifying tower, thereby forming the process of rectifying, separating and purifying the partition wall tower type molecular sieve membrane, specifically, the isopropyl alcohol solution is an aqueous solution with the isopropyl alcohol content of 20-60 percent by mass, the temperature is 20-60 ℃ and the pressure is normal pressure or low pressure, and is taken as the raw material to enter from the middle position at the left side of the dehydration section of the partition wall tower type adsorption rectifying tower and carry out the conventional rectification in the I phase zone of the isopropyl alcohol/water binary system, the water distilled from the bottom of the dehydration section and other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters are discharged out of the system for treatment, the isopropyl alcohol content generated at the upper part of the dehydration section is slightly lower than the gas phase distillate composed of isopropyl alcohol/water azeotrope, the temperature is 75-85 ℃ and the pressure is 0.1-0.3 MPa, the gas phase distillate is heated to 120-130 ℃ by a superheating coil and then enters a molecular sieve membrane separator A for membrane separation, permeate water flows out from the permeation side and forms a liquid water discharge system after heat exchange and vacuuming condensation by a hollow baffle channel, the non-permeation gas with the components of 88-90% isopropyl alcohol and 10-12% water flows out from the non-permeation side, part of the non-permeation gas returns to the superheating coil inlet at the dehydration section side or the isopropyl alcohol refining section side and enters the membrane separator A or the membrane separator B for regulating the permeation quantity and the water permeation pressure in the membrane separator, part of the liquid formed by a condenser or a gas-liquid equilibrium separator of a membrane rectifying tower independent of a partition tower type molecular sieve is subjected to heat exchange, enters from the middle part of the section as a feed of an isopropyl alcohol refining section and is subjected to conventional rectification in a II phase region of an isopropyl alcohol/water binary system, isopropyl alcohol products with purity of more than or equal to 99.9% are distilled out at the bottom of the isopropyl alcohol refining section, gas-phase distillates with isopropyl alcohol content slightly higher than that of isopropyl alcohol/water azeotrope formed at the top of the isopropyl alcohol products are generated, the gas-phase distillates enter a molecular sieve membrane separator B after passing through a hot coil pipe, permeate water flows out from a permeation side, and is subjected to heat exchange and vacuumizing condensation through a hollow partition channel to form a liquid water discharge system, non-permeation gas with components of 90-92% isopropyl alcohol and 8-10% water flows out from a non-permeation side, and all the non-permeation gas enters into the condenser or the gas-liquid equilibrium separator independent of the partition tower type molecular sieve membrane rectifying tower, the liquid formed is used as the feed of the isopropanol refining section after heat exchange, enters from the middle part of the section and is subjected to conventional rectification in the II phase zone of an isopropanol/water binary system, so that the isopropanol is further recovered.
2. The membrane rectifying separation and purification process of separating wall tower type isopropanol solution molecular sieve of claim 1, wherein the molecular sieve membrane separator consists of ceramic with multiple channels as support and coated with circular membrane tube comprising 3A, 4A, 5A, carbon nanotube or carbon molecular sieve selective material, or plate and frame membrane and membrane assembly comprising sealing element, fixing element and flange pipeline, and is fed with inner pressure or outer pressure, cross flow or vertical flow.
3. The method for molecular sieve membrane distillation separation and purification of isopropanol solution in a partition tower type as claimed in claim 1, wherein the membrane components or membrane materials of the two molecular sieve membrane separators a and B are different in selection, and the hollow partition plates are different in arrangement positions, including the radius of the dehydration section being larger than that of the isopropanol refining section.
4. The membrane rectifying separation and purification method of molecular sieve membrane tower type isopropyl alcohol solution according to claim 1, wherein 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 the water permeated from the permeation side of the molecular sieve membrane separator contains a small amount of isopropyl alcohol, the water is not directly discharged from the bottom of the hollow partition plate, but returned to the dehydration section for further recovery of isopropyl alcohol, wherein the permeate water with a small isopropyl alcohol content flows into the dehydration section from the lower through hole, and the permeate water with a large isopropyl alcohol content flows into the dehydration section from the middle through hole.
5. A molecular sieve membrane rectifying separation and purifying method for a separation wall tower type isopropanol solution, as set forth in claim 1, wherein the two molecular sieve membrane separators A and B are replaced by an osmotic gasifying membrane separator for liquid phase feeding, gas phase permeation and discharging, wherein the gas phase distillate with the isopropanol content slightly lower than that of the isopropanol/water azeotrope composition generated at the upper part of the conventional rectifying and dewatering section of the separation wall tower type osmotic gasifying membrane rectifying and dewatering section is fed into a separate external condenser or a gas-liquid equilibrium separator, the formed liquid enters the osmotic gasifying membrane separator from the inlet end of the osmotic gasifying membrane separator at the dewatering section side for osmotic gasification, the water liquid permeated from the osmotic side flows into the hollow partition plate channel and is pumped from the bottom thereof to be vacuumized, cooled and discharged, the non-osmotic liquid flows out from the non-osmotic side, the components of the method are slightly higher than the components of an isopropyl alcohol-water binary azeotropic system, the isopropyl alcohol product directly enters a feed inlet positioned in an isopropyl alcohol refining section to carry out conventional rectification of the isopropyl alcohol-water binary system in a phase II region, the isopropyl alcohol product flows out from the bottom of the isopropyl alcohol refining section, a gas phase distillate slightly higher than the components of the isopropyl alcohol-water binary azeotropic system flows out from the upper part of the isopropyl alcohol refining section, the gas phase distillate slightly lower than the components of the isopropyl alcohol-water azeotropic system generated by the upper part of the conventional rectification of the dehydration section is mixed with the gas phase distillate slightly lower than the components of the isopropyl alcohol-water azeotropic system, and then the mixture 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 dehydrated, or enters the dehydration section from a position close to the upper part of the isopropyl alcohol refining section to be further recovered.
6. The method for rectifying, separating and purifying molecular sieve membrane of isopropanol solution in tower type with partition wall as claimed in claim 4, wherein said two molecular sieve membrane separators A and B are replaced by a pervaporation membrane separator for liquid phase feeding and gas phase permeation discharging, and the membrane materials of the pervaporation membrane mainly comprise plate-frame membrane components, modified sodium alginate, chitosan membrane, sodium alginate and zeolite composite membrane materials, hollow fiber membrane components and polymer membrane materials.
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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 |