CN114591144B - Tower type isopropanol solution adsorption, rectification, separation and purification method - Google Patents
Tower type isopropanol solution adsorption, rectification, 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 264
- 238000001179 sorption measurement Methods 0.000 title claims abstract description 173
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000000926 separation method Methods 0.000 title claims abstract description 23
- 238000000746 purification Methods 0.000 title claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 71
- 239000003463 adsorbent Substances 0.000 claims abstract description 57
- 239000007788 liquid Substances 0.000 claims abstract description 36
- 239000000243 solution Substances 0.000 claims abstract description 22
- 238000011010 flushing procedure Methods 0.000 claims abstract description 19
- 239000002245 particle Substances 0.000 claims abstract description 18
- 239000007787 solid Substances 0.000 claims abstract description 16
- 229910002056 binary alloy Inorganic materials 0.000 claims abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 13
- 239000007864 aqueous solution Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 230000001174 ascending effect Effects 0.000 claims abstract description 4
- 239000012071 phase Substances 0.000 claims description 36
- 238000012546 transfer Methods 0.000 claims description 20
- 238000004821 distillation Methods 0.000 claims description 19
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 17
- 238000000605 extraction Methods 0.000 claims description 16
- 238000000895 extractive distillation Methods 0.000 claims description 14
- 230000008929 regeneration Effects 0.000 claims description 13
- 238000011069 regeneration method Methods 0.000 claims description 13
- 238000010992 reflux Methods 0.000 claims description 11
- 238000003795 desorption Methods 0.000 claims description 10
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 8
- 238000011068 loading method Methods 0.000 claims description 7
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 6
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 6
- 239000007791 liquid phase Substances 0.000 claims description 6
- 239000012153 distilled water Substances 0.000 claims description 5
- RDOXTESZEPMUJZ-UHFFFAOYSA-N anisole Chemical compound COC1=CC=CC=C1 RDOXTESZEPMUJZ-UHFFFAOYSA-N 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 229910001385 heavy metal Inorganic materials 0.000 claims description 4
- UZKWTJUDCOPSNM-UHFFFAOYSA-N methoxybenzene Substances CCCCOC=C UZKWTJUDCOPSNM-UHFFFAOYSA-N 0.000 claims description 4
- QPJVMBTYPHYUOC-UHFFFAOYSA-N methyl benzoate Chemical compound COC(=O)C1=CC=CC=C1 QPJVMBTYPHYUOC-UHFFFAOYSA-N 0.000 claims description 4
- 239000002808 molecular sieve Substances 0.000 claims description 4
- 238000004064 recycling Methods 0.000 claims description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 4
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 3
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 3
- 239000004917 carbon fiber Substances 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 3
- 239000000835 fiber Substances 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- -1 isobutyl ester Chemical class 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 claims description 2
- XNWFRZJHXBZDAG-UHFFFAOYSA-N 2-METHOXYETHANOL Chemical compound COCCO XNWFRZJHXBZDAG-UHFFFAOYSA-N 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 229940095102 methyl benzoate Drugs 0.000 claims description 2
- 239000011259 mixed solution Substances 0.000 claims description 2
- HUAZGNHGCJGYNP-UHFFFAOYSA-N propyl butyrate Chemical compound CCCOC(=O)CCC HUAZGNHGCJGYNP-UHFFFAOYSA-N 0.000 claims description 2
- 239000000741 silica gel Substances 0.000 claims description 2
- 229910002027 silica gel Inorganic materials 0.000 claims description 2
- 230000000274 adsorptive effect Effects 0.000 claims 17
- 238000010521 absorption reaction Methods 0.000 claims 6
- 238000011049 filling Methods 0.000 claims 2
- 238000005191 phase separation Methods 0.000 claims 2
- XTUSEBKMEQERQV-UHFFFAOYSA-N propan-2-ol;hydrate Chemical compound O.CC(C)O XTUSEBKMEQERQV-UHFFFAOYSA-N 0.000 abstract description 6
- 238000010438 heat treatment Methods 0.000 abstract description 5
- 239000007789 gas Substances 0.000 description 46
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000009835 boiling Methods 0.000 description 3
- 239000012159 carrier gas Substances 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000009849 deactivation Effects 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 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
- 230000008021 deposition Effects 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000005373 pervaporation Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000002918 waste heat 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
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
- C07C29/84—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation by extractive distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention discloses a tower type isopropyl alcohol solution adsorption, rectification and purification method, wherein an aqueous solution with isopropyl alcohol (IPA) content of 20-60% (w/w) is introduced into an adsorption rectification system consisting of a lower section of an adsorption rectification tower, a middle section of the adsorption rectification tower and an upper section of the adsorption rectification tower, wherein the upper section and the lower section are conventional rectification towers, the middle section consists of a gas-liquid equilibrium separation disc, a material flow distribution tray, a heating and cooling coil and a solid particle adsorbent or a regular adsorbent, water and other trace impurity components are discharged from the bottom of the lower section, isopropyl alcohol products with purity of more than or equal to 99.9% (w/w) are distilled from the top of the upper section, a material flow which is near the azeotropic point of an isopropyl alcohol-water binary system is introduced from the top of the upper section, a part of the water enters into the adsorption rectification system as flushing gas/liquid from the upper part of the middle section, the water is reversely contacted with the ascending material flow to perform adsorption and rectification steady state, and a part of the water is returned to the top of the lower section to further separate and recover isopropyl alcohol, and the product yield reaches more than 99%.
Description
Technical Field
The invention belongs to the field of dehydration separation and purification of isopropanol solution to prepare high-purity isopropanol, and particularly relates to a tower type isopropanol solution adsorption 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 isopropanol under normal pressure of 82.45 ℃, water of 100 ℃, and an azeotrope formed by an isopropanol-water solution being the lowest boiling point. Therefore, to obtain isopropyl alcohol of higher purity, general distillation cannot be realized, and special separation methods such as constant (azeotropic) distillation with the addition of an azeotropic agent (benzene, etc.), energy-saving partition constant boiling distillation, extractive distillation with the addition of an extractant (ethylene glycol, etc.), salt-adding extractive distillation, gap extractive distillation, 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 adsorption rectification method combines adsorption and rectification processes, namely, an independent adsorption unit is additionally arranged between two rectification towers (a tower I and a tower II), and the adsorption unit still has special selectivity in the range of azeotrope formed by isopropanol-water which cannot be passed by a conventional rectification tower (I) adsorbed in a phase I region formed by an isopropanol/water binary system, so that the gas-liquid balance limit faced by conventional rectification is overcome, an isopropanol aqueous solution can pass the azeotropic point, and the separation is carried out by continuously adopting the conventional rectification tower (II) in the phase II region formed by the isopropanol/water binary system, thereby obtaining an isopropanol product at the bottom of the tower. Because of the binary system composed of isopropanol/water solution, there are I and II phase regions with larger gas-liquid balance difference, which means that the rectification mass transfer pushing force in the two phase regions is larger, and the separation can still be carried out by adopting a conventional rectification method. The adsorption is to separate the isopropanol/water binary azeotropic component by utilizing the adsorbent, wherein the adsorption selectivity of the adsorbent to water in the isopropanol/water binary azeotropic component is greater than that of the isopropanol, but the saturated adsorption capacity of the adsorbent is considered, so that the adsorption can be used as an important technical means for overcoming the bottleneck of the isopropanol/water binary azeotropic component, and the water in the isopropanol/water binary azeotropic component is rapidly and selectively adsorbed, so that the balance of the isopropanol/water binary azeotropic system is broken, and the larger gas-liquid balance driving force in the II-phase region of the isopropanol/water binary system is continuously utilized to perform conventional rectification operation. Specifically, heavy component water flows out from the bottom of a rectifying tower (I), tower top gas which is close to azeotropic components and flows out from the top of the rectifying tower flows back to the rectifying tower (I) as reflux after passing through a gas-liquid balancer, the gas enters an adsorption unit after further overheating, wherein the adsorption unit can obtain non-adsorption phase material flow which crosses the azeotropic point through a Temperature Swing Adsorption (TSA) or Pressure Swing Adsorption (PSA) method by selectively adsorbing water, the isopropanol content is about 88-90%, the water content is 10-12%, the non-adsorption phase material flow enters the rectifying tower (II) for rectifying separation, the gas which is close to azeotropic components and flows out from the top of the rectifying tower is returned to the adsorption unit for circulating treatment after passing through the gas-liquid balancer, and the liquid enters the rectifying tower (II) as reflux for continuous rectification, and the isopropyl alcohol product flows out from the bottom of the rectifying tower (II). In the adsorption unit, when Temperature Swing Adsorption (TSA) is used, the regeneration requires heating of the hot carrier gas to 120 ℃ or higher, however, since isopropanol readily undergoes self-polymerization reaction at temperatures exceeding 120 ℃ or reacts with the aluminosilicate-containing adsorbent to cause carbon deposition or deactivation of the adsorbent, and the regenerated waste gas generated by the hot carrier gas still needs to be recycled after treatment, and at the same time, the yield of isopropanol is reduced. Some temperature swing adsorption rectification processes adopt liquid phase feed adsorption units, a gas-liquid balancer at the tops of rectifying towers (I) and (II) is omitted, a part of liquid after heat exchange is used as reflux of each rectifying tower, and a part of liquid enters or returns to the adsorption units to be subjected to liquid phase adsorption. Self-polymerization or other reactions also occur during regeneration. At present, there is a further research and development method for adsorption rectification of liquid phase feeding of a circulating bed at home and abroad, namely, glycol is adopted as a solid adsorbent carrier liquid, the adsorbent is circulated in the operation of an adsorption unit, the adsorbent carrier liquid after thermal regeneration enters an adsorption regeneration tower and returns to the adsorption tower for recycling, and a material flow which flows out of the top of the adsorption tower and skips the azeotropic point enters a rectification tower (II) for further rectification. In the disclosed patent of the full-temperature pressure swing adsorption, rectification and separation and purification method for high-purity isopropanol, an adsorption unit adopts a gas phase Pressure Swing Adsorption (PSA) process, and is characterized in that the desorption gas rich in water is mixed with isopropanol solution (raw materials) after heat exchange or condensation treatment and returns to a rectifying tower (I) for further understanding the water and isopropanol in the gas, heating or hot carrier gas introduction is not needed during desorption and regeneration, and the desorption is carried out only through the change of pressure while the yield is very high, so that the problem of the deactivation of the adsorbent caused by the over high desorption and regeneration temperature is avoided. However, this method still requires adding multiple independent pressure swing adsorption towers between two rectification towers, and the investment and cost are high. That is, the adsorption and rectification units in the existing adsorption and rectification process are combined by independent units, so that the investment of equipment and control systems related to each unit and the consistency adjustment of the operation conditions of the units are required, and the integrated coupling of adsorption and rectification cannot be really realized.
Disclosure of Invention
The invention provides a tower type isopropyl alcohol solution adsorption, distillation and separation and purification method, which is characterized in that a steady mass transfer process is achieved by utilizing adsorption and desorption regeneration of a filler type adsorbent combined with selective adsorption and equilibrium distillation, the adsorbent is filled in a rectifying tower to form an adsorption rectification middle bed section, so that the rectifying tower is divided into an upper section and a lower section, a tower type adsorption rectification process is formed, mass transfer between isopropyl alcohol and water components close to an azeotropic component is realized in the adsorption rectification section, the water concentration in the adsorption rectification section is continuously changed while the balance of the azeotropic component is destroyed under continuous adsorption, so that the balance is formed, the whole adsorption rectification bed layer always achieves a steady state, namely, the mass transfer in the adsorption rectification bed section is irrelevant to each time and space point in the bed layer, thereby crossing the azeotropic point between isopropyl alcohol and water, isopropyl alcohol products flow out from the lower section, and low energy consumption, low cost, high purity and high purity (99.99% isopropyl alcohol and 99% isopropyl alcohol) are produced, and the defects of the existing method of stable operation, low energy consumption, high purity and the like are overcome. For this purpose, the invention adopts the following technical scheme:
a method for separating and purifying isopropanol solution by adsorption and rectification includes such steps as loading the aqueous solution with 20-60% (wt.%) of Isopropanol (IPA) at 20-60 deg.C and ordinary pressure or low pressure in the I-phase region of binary system of isopropanol/water, rectifying the distilled water from lower tower, water-soluble heavy metal ions and trace heavy component impurities including high-alcohol esters, treating by discharge system, generating gas-phase distillate with isopropanol content slightly lower than that of isopropanol/water azeotrope (87.5% isopropanol and 17.5% water under ordinary pressure), flowing the liquid back to lower tower via gas-liquid balance separating disk consisting of coiled tubes at 75-85 deg.C and 0.1-0.6 MPa, the gas enters an adsorption distillation middle section which takes a gas distributor as a column plate and is filled with an adsorbent on the column plate, mass transfer of adsorption and distillation is carried out between isopropanol and water components in the gas phase close to the azeotropic component in the adsorption distillation middle section, wherein water is continuously adsorbed and distilled along an axial adsorption distillation bed layer so that the concentration of the isopropanol in the gas close to the azeotropic component reaches 88-90%, the isopropanol escapes from a top central circular outlet of the adsorption distillation middle section bed layer, the gas enters a central circular channel arranged at the upper section of the adsorption distillation column through cooling of a heat exchange disc zone, the gas flows into a conventional distillation in a II phase zone of an isopropanol/water binary system from two end outlets arranged at the middle part of the upper section of the adsorption distillation column, the product isopropanol is distilled from the bottom of the upper section of the adsorption distillation column, the purity is more than or equal to 99.9%, the gas phase distillate with the isopropanol content slightly higher than that of the isopropanol/water azeotrope composition (87.5% isopropanol and 17.5% water under normal pressure) is divided into two parts, one part is taken as flushing liquid or flushing gas to enter from the top of the middle section of the adsorption rectifying tower after heat exchange in a heat exchange disc area, and is reversely contacted with the rising adsorption gas, and desorption rectification is carried out in a bed layer of the adsorption rectifying middle section, so that mass transfer and balance are continuously carried out on adsorption, desorption and rectification in the bed layer along the axial direction of the bed layer until the gas phase at the outlet of the top of the bed layer of the adsorption rectifying middle section reaches the concentration entering the upper section of the adsorption rectifying tower, and the gas phase returns to the bed layer of the adsorption rectifying middle section after the downward flushing liquid/gas flows through a gas-liquid separation disc, and the liquid phase returns to the lower section of the adsorption rectifying tower as reflux, and the conventional rectification in the I phase area of the isopropanol/water binary system is continuously carried out; the other part is directly returned to the top of the lower section of the adsorption rectifying tower, and enters the middle section of the adsorption rectifying tower for further separation and recovery of isopropanol after passing through a gas-liquid equilibrium separation disc, and the yield of the isopropanol product reaches more than 99%.
Furthermore, the adsorption rectification middle section bed layer is filled with the adsorbent which is round or cylindrical particle stacking type, or suspension type, or honeycomb type and binding type regular adsorbent, and different adsorbent composition forms directly influence the height of the adsorption rectification middle section bed layer and the efficiency of mass transfer reaching steady operation, preferably honeycomb type and binding type regular adsorbent, and has high heat transfer efficiency and long service life, and the height of the adsorption rectification middle section bed layer is 1/5-1/3 of the height of the upper section of the adsorption rectification tower.
Furthermore, the adsorbent material filled in the middle bed layer of the adsorption rectification is silica gel, molecular sieve, carbon molecular sieve, high molecular organic matter, carbon fiber or regular composite adsorbent prepared by taking silicate fiber as a base material. Preferably, the adsorbent is a regular composite adsorbent prepared from polymer organic matters, carbon fibers or silicate fibers (containing silicon fluoride, ceramic and glass fibers) serving as a base material.
Furthermore, the flushing gas or flushing liquid is added with a part of product isopropanol to adjust the concentration of isopropanol in the adsorption and rectification middle section bed layer and the rectification mass transfer process to achieve balance.
Further, the upper section of the adsorption rectifying tower is changed into an extraction rectifying tower, one or more mixed extraction solvents are added near the top of the extraction rectifying tower, the mixed solvents comprise glycol, glycol salified mixed liquid, glycol methyl ether, ethyl acetate, benzene, anisole, toluene and derivatives thereof, propyl butyrate, isobutyl ester, diethylene glycol, methyl benzoate, n-butyl ether, vinyl n-butyl ether and various mixtures thereof, the tower top distillate is condensed, a part of condensate returns to the extraction rectifying tower as reflux, and a part of condensate is output as an isopropyl alcohol product with high purity (more than or equal to 99.99 percent); and (3) sending the bottom distillate of the extractive distillation column into an additional extractant regeneration column, distilling pure water from the top of the extractive distillation column, taking part of the distilled water as flushing fluid to replace the product isopropanol to be used for adjusting the concentration balance of isopropanol in the bed layer in the middle section of the adsorption distillation, directly discharging part of the distilled water out of the system, and distilling the enriched extraction solvent from the bottom of the extractive distillation column to be used as the extraction solvent of the extractive distillation column for recycling.
Further, the adsorption rectification middle section filled with the solid particle adsorbent is operated by adopting a circulating bed layer, fresh adsorbent slides into a feed inlet near the top of the adsorption rectification middle section from the bottom of a hopper for loading and unloading the adsorbent by gravity, the descending solid particle adsorbent in the middle section bed layer is reversely contacted with ascending adsorption gas, adsorption mass transfer and balance are carried out in the adsorption rectification middle section bed layer until the gas phase at the outlet at the top of the adsorption rectification middle section bed layer reaches the concentration entering the upper section of the adsorption rectification tower, the solid particle adsorbent for absorbing water flowing downwards is discharged from the lower part of the adsorption rectification middle section and is sent into an online adsorbent regenerator after being screened, the regenerated adsorbent is directly heated or indirectly heated for regeneration, and is lifted into the adsorbent hopper by a lifting system after being cooled to the operating temperature of the adsorption rectification middle section, and is mixed with the fresh supplementary solid particle adsorbent to enter the adsorption rectification middle section for circulating operation.
Compared with the prior art, the invention has the beneficial effects that:
(1) The adsorption and the two-tower rectification process of the traditional isopropanol-water binary system are coupled into an adsorption rectification tower, so that the adsorption and the rectification simultaneously occur in the middle section of the adsorption rectification tower to form a high-efficiency mass transfer steady state, thereby greatly reducing the investment and the operation cost of the adsorption and rectification combined process and simultaneously obtaining the high-purity isopropanol product.
(2) The invention has various and flexible forms and materials of the loaded adsorbent in the adsorption and rectification bed layer in the middle section of adsorption and rectification, and comprises solid particles, honeycomb or binding type, molecular sieve or polymer and other materials, and the operation mode of the adsorption and rectification bed layer can be a fixed bed, a suspension bed or even a circulating bed.
(3) According to the invention, through different selection of the gas/liquid for the gas/liquid separation, the equilibrium concentration of isopropanol or water in the bed layer in the middle section of the adsorption rectifying tower can be adjusted, so that the adsorption and rectification in the bed layer in the section can reach the steady state of mass transfer more easily, the azeotropic point of an isopropanol-water binary system can be skipped more efficiently and rapidly, and the energy consumption can be saved.
(4) According to the invention, the upper section of the adsorption rectifying tower is modified into the extraction rectifying tower, so that the isopropanol product with higher purity is obtained, and the equilibrium concentration of isopropanol-water binary system water in the middle section bed layer of the adsorption rectifying tower is regulated by only water produced from the extraction rectifying system, so that the mass transfer steady state is reached, and the yield of the isopropanol product is further improved.
(5) The invention also comprises a circulating bed adsorption operation mode adopted in the middle bed layer of the adsorption rectifying tower, rectification is not needed to happen simultaneously, the efficiency is higher, and the mass transfer steady state close to the theoretical value is almost reached.
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, in the adsorption, rectification and purification method of a one-tower type isopropanol solution, an aqueous solution with the Isopropanol (IPA) content of 50% (mass ratio, w/w, the same applies hereinafter) is fed as a raw material into the middle part of the lower section of an adsorption rectifying tower for conventional rectification in the I-phase region of an isopropanol/water binary system, the water content of stillage in the lower section of the adsorption rectifying tower is more than or equal to 99.6%, the isopropanol content is less than 0.4% and the stillage containing other trace heavy component impurities including water-soluble heavy metal ions and high alcohol esters is discharged for treatment by a discharging system, the isopropanol content generated at the top of the lower section of the adsorption rectifying tower is slightly lower than the gas phase distillate composed of isopropanol/water azeotrope (87.5% isopropanol and 17.5% water under normal pressure), wherein the content of isopropanol is 85%, the content of water is 15%, the temperature is 75-85 ℃ and the pressure is 0.3MPa, the liquid flows to the lower section of the adsorption rectifying tower directly as reflux through a gas-liquid equilibrium separation disc formed by a coil pipe, the gas enters the adsorption rectifying middle section of an adsorbent which takes a gas distributor as a tower plate and is filled with spherical particles on the tower plate, mass transfer of adsorption and rectification is carried out between the isopropanol and water components in the gas phase close to the azeotropic component in the adsorption rectifying middle section, the water is continuously adsorbed and rectified along an axial adsorption rectifying bed layer to enable the concentration of the isopropanol in the gas close to the azeotropic component to reach 89%, the isopropanol escapes from a top central circular outlet of the bed layer of the adsorption rectifying middle section, and the gas enters a central circular channel arranged at the upper section of the adsorption rectifying tower through cooling of a heat exchange disc area, the method comprises the steps that the isopropyl alcohol is distilled from the bottom of the upper section of an adsorption rectifying tower, the purity is more than or equal to 99.9%, the gas phase distillate with the isopropyl alcohol content slightly higher than that of an isopropyl alcohol/water azeotrope is distilled from the top of the upper section of the adsorption rectifying tower, the gas phase distillate is composed of 89.5% of isopropyl alcohol concentration and 10.5% of water content, the gas phase distillate is divided into two gas flows, one half of the gas flow is subjected to heat exchange in a heat exchange disc area and then enters from the top of the middle section of the adsorption rectifying tower as flushing gas, the flushing gas is reversely contacted with the rising adsorption gas, and desorption rectifying is carried out in a bed layer of the middle section of the adsorption rectifying tower, so that mass transfer and balance are continuously carried out along the axial direction of the bed layer, the gas phase of the outlet of the top of the bed layer of the middle section of the adsorption rectifying tower reaches the concentration of the upper section of the adsorption rectifying tower, and the flushing liquid/gas flowing downwards returns to the middle section of the adsorption rectifying tower as the normal reflux phase of the adsorption rectifying tower after being subjected to gas-liquid separation disc, and the gas phase is returned to the middle section of the adsorption rectifying tower as the normal reflux of the isopropyl alcohol in the middle section of the adsorption rectifying tower; the other half of the isopropyl alcohol is directly returned to the top of the lower section of the adsorption rectifying tower, enters the middle section of the adsorption rectifying tower after passing through a gas-liquid equilibrium separation disc, and is further separated and recycled, and the product yield is 99%.
Example 2
As shown in fig. 2, in the method for adsorption, rectification and purification of a one-tower type isopropanol solution, the upper section of the adsorption rectification tower in the embodiment 1 is changed into an extraction rectification tower, an extractant of a glycol salified mixed solution is added near the top of the extraction rectification tower, the overhead distillate is condensed, 15% of condensate is returned to the extraction rectification tower as reflux, and 85% of condensate is output as a high-purity (more than or equal to 99.99%) isopropanol product; and (3) sending the bottom distillate of the extractive distillation column into an additional extractant regeneration column, wherein a heating steam coil is arranged in the column to heat to 120-160 ℃, pure water is distilled out from the top of the regeneration column, about 15-30% of pure water is used as flushing fluid to replace the product isopropanol to be used for adjusting the concentration balance of isopropanol in the bed layer in the middle section of adsorption distillation, the rest of pure water is directly discharged out of the system, and the enriched extraction solvent is distilled out from the bottom of the extractive distillation column to be used as the extraction solvent of the extractive distillation column for recycling.
Example 3
As shown in fig. 3, in the adsorption, rectification and purification method of a one-tower type isopropyl alcohol solution, in the adsorption, rectification middle section filled with solid particle adsorbent in embodiment 1, a circulating bed layer is adopted for operation, fresh adsorbent slides into a feed inlet near the top of the adsorption, rectification middle section from the bottom of a hopper for loading and unloading adsorbent through gravity drop, enters the adsorption, rectification middle section, the descending solid particle adsorbent in the middle section bed layer is in reverse contact with ascending adsorption gas, adsorption mass transfer and balance are carried out in the adsorption, rectification middle section bed layer until the gas phase at the outlet at the top of the adsorption, rectification middle section bed layer reaches the concentration entering the upper section of the adsorption, namely, the isopropyl alcohol concentration is 89%, the water content is 11%, and the solid particle adsorbent of the downward flow adsorption moisture is discharged from the lower part of the adsorption, purified and then sent into an online adsorbent regenerator, hot nitrogen with the temperature of 160-200 ℃ is adopted for direct heating regeneration, the waste heat nitrogen is cooled and filtered and then used as lifting gas of a lifting system for circulation, and the regenerated adsorbent enters the adsorption, fresh particle adsorbent is mixed with the circulating solid particle adsorbent through the lifting system after the operation of the lifting hopper to the operation temperature of the adsorption, rectification middle section.
Example 4
In the method for separating and purifying the isopropanol solution by adsorption and rectification of a tower type, in the embodiment 1, one half of one gas is flushing gas, 5-10% of isopropanol is added into the product and mixed, and the flushing gas enters from the top of the middle section of the adsorption and rectification tower after heat exchange of a heat exchange disc zone, so that the concentration of the isopropanol in the adsorption and rectification mass transfer process in the middle section bed of the adsorption and rectification is regulated to reach balance.
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 (5)
1. A method for separating and purifying the isopropanol solution by adsorption rectification includes such steps as loading the aqueous solution with isopropanol content of 20-60% at 20-60 deg.C and pressure of normal or low pressure as raw material to the first phase region of an adsorption rectifying tower consisting of upper, middle and lower three stages, rectifying the water from the lower stage of said tower, and the trace heavy metal ions and high alcohol esters, discharging the impurities from the system, treating the gas phase distillate with isopropanol content slightly lower than that of isopropanol/water azeotrope, flowing the liquid to the lower stage of said rectifying tower at 75-85 deg.C under 0.1-0.6 MPa, loading the gas to the adsorption rectifying tower, loading the gas component between the isopropanol and water component in the middle stage of said rectifying tower, and concentrating the water in the middle stage of said rectifying tower, and concentrating the water phase stream at the same time, and concentrating the top of said rectifying tower by the absorption rectifying tower, and cooling the absorption rectifying tower, and concentrating the water in the middle stage by the absorption rectifying tower, and cooling the tower, and concentrating the water phase stream by the absorption rectifying tower, and concentrating the water in the middle of said rectifying tower, and cooling tower, and concentrating the water phase stream by the absorption rectifying tower, and concentrating the gas-liquid by the absorption rectifying tower, and the gas-liquid phase separation tray, and the liquid at 90-gas phase separation. The purity is more than or equal to 99.9%, the gas phase distillate with the isopropanol content slightly higher than that of the isopropanol/water azeotrope is divided into two parts, one part is taken as flushing liquid or flushing gas to enter from the top of the middle section of the adsorption rectifying tower after heat exchange through a heat exchange disc area, and is reversely contacted with the rising adsorption gas, and desorption rectification is carried out in the middle section bed layer of the adsorption rectifying tower, so that adsorption, desorption and rectification in the bed layer are simultaneously carried out along the axial direction of the bed layer continuously until the gas phase at the outlet of the top of the middle section bed layer of the adsorption rectifying tower reaches the concentration entering the upper section of the adsorption rectifying tower, and the downward flushing liquid/gas returns to the middle section bed layer of the adsorption rectifying tower after passing through a gas-liquid separation disc, and the liquid phase returns to the lower section of the adsorption rectifying tower directly as reflux, and the conventional rectification in the I phase area of the isopropanol/water binary system is continued; the other strand is directly returned to the top of the lower section of the adsorption rectifying tower, enters the middle section of the adsorption rectifying tower after passing through a gas-liquid equilibrium separation disc, and is further separated and recycled, wherein the yield of the isopropanol product reaches more than 99 percent, and the bed layer of the middle section of the adsorption rectifying tower is filled with the adsorbent which is round or cylindrical particles stacked or suspended or honeycomb and binding type regular adsorbent, and the filling height of the bed layer of the middle section of the adsorption rectifying tower is 1/5-1/3 of the filling height of the upper section of the adsorption rectifying tower.
2. The method for adsorptive rectification separation and purification of a tower type isopropyl alcohol solution according to claim 1, wherein the adsorbent material filled in the middle bed layer of the adsorptive rectification tower is one or more combinations of silica gel, molecular sieve, carbon fiber or regular composite adsorbent made of silicate fiber as a base material.
3. The method for adsorptive rectification separation and purification of a tower type isopropyl alcohol solution as claimed in claim 1, wherein said flushing gas or flushing liquid is added with a part of isopropyl alcohol product to adjust the isopropyl alcohol concentration in the adsorption and rectification mass transfer process carried out simultaneously in the middle bed of the adsorptive rectification tower to reach equilibrium.
4. The method for adsorptive rectification separation and purification of a one-tower type isopropyl alcohol solution as claimed in claim 1, wherein the upper section of the adsorptive rectification column is changed into an extractive rectification column, one or more mixed extraction solvents selected from ethylene glycol, ethylene glycol salified mixed solution, ethylene glycol methyl ether, ethyl acetate, benzene, anisole, toluene, propyl butyrate, isobutyl ester, diethylene glycol, methyl benzoate, n-butyl ether and vinyl n-butyl ether are added near the top of the extractive rectification column, the top of the column is condensed, a part of condensate is returned to the extractive rectification column at the upper section of the adsorptive rectification column as reflux, and a part of condensate is output as a high-purity isopropyl alcohol product with purity of 99.99% or more; and (3) sending the bottom distillate of the extractive distillation column into an additional extractant regeneration column, distilling pure water from the top of the extractive distillation column, taking part of the distilled water as flushing fluid to replace the product isopropanol to be used for adjusting the concentration balance of isopropanol in the middle bed layer of the adsorption distillation column, directly discharging part of the distilled water out of the system, and distilling the enriched extraction solvent from the bottom of the extractive distillation column to be used as the extraction solvent of the extractive distillation column for recycling.
5. The method for adsorptive rectification and purification of a tower type isopropyl alcohol solution as claimed in claim 1, wherein the middle section of the adsorptive rectification tower filled with solid particle adsorbent is operated by adopting a circulating bed layer, fresh adsorbent slides into a feed inlet near the top of the adsorptive rectification tower from the bottom of a hopper for loading and unloading the adsorbent by gravity drop, enters the middle section of the adsorptive rectification tower, the descending solid particle adsorbent in the middle section bed layer is reversely contacted with ascending adsorption gas, mass transfer and balance of adsorption and rectification are simultaneously carried out in the middle section bed layer of the adsorptive rectification tower until the gas phase at the outlet of the top of the middle section bed layer of the adsorptive rectification tower reaches the concentration entering the upper section of the adsorptive rectification tower, the solid particle adsorbent of downward flowing adsorption moisture is discharged from the lower part of the middle section of the adsorptive rectification tower and is fed into an online adsorbent regenerator after being screened, the regenerated adsorbent is directly heated or indirectly heated and regenerated after being cooled to the operating temperature of the middle section of the adsorptive rectification tower, the adsorbent is lifted into the adsorbent hopper by a lifting system, and the solid particle adsorbent mixed with the fresh solid particle adsorbent enters the adsorptive rectification tower for circulating operation.
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