CN116271919A - Device and method for separating mixture of methanol, ethanol, toluene and water - Google Patents
Device and method for separating mixture of methanol, ethanol, toluene and water Download PDFInfo
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- CN116271919A CN116271919A CN202310354161.XA CN202310354161A CN116271919A CN 116271919 A CN116271919 A CN 116271919A CN 202310354161 A CN202310354161 A CN 202310354161A CN 116271919 A CN116271919 A CN 116271919A
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- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 title claims abstract description 410
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 231
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 165
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 162
- 239000000203 mixture Substances 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000010992 reflux Methods 0.000 claims abstract description 73
- BRMNIPUJQIHQIE-UHFFFAOYSA-N ethanol;toluene;hydrate Chemical compound O.CCO.CC1=CC=CC=C1 BRMNIPUJQIHQIE-UHFFFAOYSA-N 0.000 claims abstract description 60
- 239000000463 material Substances 0.000 claims abstract description 60
- 238000004821 distillation Methods 0.000 claims abstract description 42
- 238000005191 phase separation Methods 0.000 claims abstract description 33
- BKBMACKZOSMMGT-UHFFFAOYSA-N methanol;toluene Chemical compound OC.CC1=CC=CC=C1 BKBMACKZOSMMGT-UHFFFAOYSA-N 0.000 claims description 47
- 230000007704 transition Effects 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 13
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- -1 methanol-ethanol-toluene-water Chemical compound 0.000 claims description 7
- 238000000926 separation method Methods 0.000 abstract description 36
- 239000000126 substance Substances 0.000 abstract description 14
- 239000007788 liquid Substances 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 abstract description 4
- XPNGNIFUDRPBFJ-UHFFFAOYSA-N (2-methylphenyl)methanol Chemical compound CC1=CC=CC=C1CO XPNGNIFUDRPBFJ-UHFFFAOYSA-N 0.000 abstract 1
- RUGISKODRCWQNE-UHFFFAOYSA-N 2-(2-methylphenyl)ethanol Chemical compound CC1=CC=CC=C1CCO RUGISKODRCWQNE-UHFFFAOYSA-N 0.000 abstract 1
- CMQCNTNASCDNGR-UHFFFAOYSA-N toluene;hydrate Chemical compound O.CC1=CC=CC=C1 CMQCNTNASCDNGR-UHFFFAOYSA-N 0.000 abstract 1
- 235000019441 ethanol Nutrition 0.000 description 64
- 239000000047 product Substances 0.000 description 49
- 239000002994 raw material Substances 0.000 description 48
- 239000003921 oil Substances 0.000 description 20
- 239000002904 solvent Substances 0.000 description 15
- 238000009835 boiling Methods 0.000 description 13
- 238000000605 extraction Methods 0.000 description 13
- 230000018044 dehydration Effects 0.000 description 11
- 238000006297 dehydration reaction Methods 0.000 description 11
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 9
- 239000012535 impurity Substances 0.000 description 9
- 238000005265 energy consumption Methods 0.000 description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 6
- NJSUFZNXBBXAAC-UHFFFAOYSA-N ethanol;toluene Chemical compound CCO.CC1=CC=CC=C1 NJSUFZNXBBXAAC-UHFFFAOYSA-N 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 5
- 239000003814 drug Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 4
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 description 3
- 229940079593 drug Drugs 0.000 description 3
- 239000000975 dye Substances 0.000 description 3
- 239000012847 fine chemical Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 239000000575 pesticide Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 2
- 229960000583 acetic acid Drugs 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 239000012223 aqueous fraction Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
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- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000002910 solid waste Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- SPSSULHKWOKEEL-UHFFFAOYSA-N 2,4,6-trinitrotoluene Chemical compound CC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O SPSSULHKWOKEEL-UHFFFAOYSA-N 0.000 description 1
- 244000043261 Hevea brasiliensis Species 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000012271 agricultural production Methods 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 238000010533 azeotropic distillation Methods 0.000 description 1
- 238000000998 batch distillation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- PASDCCFISLVPSO-UHFFFAOYSA-N benzoyl chloride Chemical compound ClC(=O)C1=CC=CC=C1 PASDCCFISLVPSO-UHFFFAOYSA-N 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- NEHMKBQYUWJMIP-NJFSPNSNSA-N chloro(114C)methane Chemical compound [14CH3]Cl NEHMKBQYUWJMIP-NJFSPNSNSA-N 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 239000012043 crude product Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- VAYGXNSJCAHWJZ-UHFFFAOYSA-N dimethyl sulfate Chemical compound COS(=O)(=O)OC VAYGXNSJCAHWJZ-UHFFFAOYSA-N 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000012362 glacial acetic acid Substances 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Natural products C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
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- 150000002825 nitriles Chemical class 0.000 description 1
- 239000012860 organic pigment Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- CVHZOJJKTDOEJC-UHFFFAOYSA-N saccharin Chemical compound C1=CC=C2C(=O)NS(=O)(=O)C2=C1 CVHZOJJKTDOEJC-UHFFFAOYSA-N 0.000 description 1
- 229940081974 saccharin Drugs 0.000 description 1
- 235000019204 saccharin Nutrition 0.000 description 1
- 239000000901 saccharin and its Na,K and Ca salt Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000001577 simple distillation Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000013517 stratification Methods 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
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- 239000000015 trinitrotoluene Substances 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000003809 water extraction Methods 0.000 description 1
Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention belongs to the technical field of chemical separation, and particularly relates to a device and a method for separating a mixture of methanol, ethanol, toluene and water. The device comprises a distillation kettle, a rectifying tower, a tower kettle, a reboiler, a condenser, a reflux tank, a phase separation tank and a receiving tank. The method is characterized in that binary or ternary azeotropy is generated between toluene and methanol, ethanol and water in the materials; because toluene-methanol, toluene-ethanol, toluene-water binary azeotrope system and toluene-ethanol-water ternary azeotrope system generate positive deviation to Raoult's law, the characteristic of minimum azeotropic point is formed, and the separation purpose is achieved by increasing or reducing the water consumption in the system and utilizing the characteristics of different binary and ternary azeotrope components and liquid layering. The invention can separate and obtain methanol, ethanol and toluene products with purity more than 99.5 percent. The method has the advantages of short process flow, less equipment investment, convenient operation and thorough separation of products, and can be applied to industrialization.
Description
Technical Field
The invention belongs to the technical field of chemical separation, and particularly relates to a device and a method for separating a mixture of methanol, ethanol, toluene and water.
Background
Methanol (methyl alcohol), also known as hydroxy methane, is the most structurally simple saturated monohydric alcohol, and has a chemical formula of CH3OH, a molecular weight of 32.04, a relative density of 0.792 (20/4 ℃), a melting point of-97.8 ℃ and a boiling point of 64.7 ℃, and is miscible with water, ethanol, diethyl ether, benzene, ketone, nitrile, halogenated hydrocarbon and many other organic solvents. The methanol has wide application, is a basic organic chemical raw material and high-quality fuel, is mainly applied to the fields of fine chemical industry, plastics and the like, is one of important basic organic raw materials of pesticides, medicines and materials, can be used as a novel alcohol-based fuel or added into gasoline for blending and burning after deep processing, and can be used for manufacturing various organic products such as acetic acid, methyl chloride, methylamine, dimethyl sulfate and the like. Toluene (Methyl Benzene) is an organic compound with a chemical formula of C7H8, a molecular weight of 92.14, a relative density of 0.872 (20/4 ℃), a melting point of-94.9 ℃ and a boiling point of 110.6 ℃, is a colorless and volatile liquid with special fragrance, can be mixed with ethanol, diethyl ether, acetone, chloroform, carbon disulfide and glacial acetic acid, and is very slightly soluble in water. Toluene is mainly prepared from crude oil through petrochemical process, and is used as solvent for oils, resins, natural rubber and synthetic rubber, coal tar, asphalt, cellulose acetate, cellulose paint and varnish, and photographic plate making and ink. Toluene is also the main raw material for organic synthesis, especially for organic synthesis of benzoyl chloride and phenyl, saccharin, trinitrotoluene and many dyes, and is also a component of aviation and automotive gasoline. Toluene is used as a solvent in a large amount, is an important raw material for organic chemical industry, and is widely used for dyes; a medicine; a pesticide; explosive powder; an auxiliary agent; the production of fine chemicals such as fragrances, and also for the synthetic materials industry; among them, it is most important in polyurethane products, dyes and organic pigments, rubber aids, medicines, explosives, etc. Ethanol (ET) is commonly called alcohol, is an organic compound, has a structural formula of CH3CH2OH or C2H5OH, has a molecular formula of C2H6O, has a molecular weight of 40.07, a melting point of-114.0 ℃, a boiling point of 78.3 ℃ and a relative density of 0.7893 (20/4 ℃), can be mutually dissolved with water in any ratio, and can be mixed with chloroform, diethyl ether, methanol, acetone and other most organic solvents; ethanol has wide application in the fields of electronic industry, chemical industry, medical and health, food industry, agricultural production and the like.
The byproducts in the manufacturing processes of pesticides, medicines, electronic materials and the like are methanol-ethanol-toluene-water mixtures, the materials are required to be separated through rectification, and if the materials are not separated, the materials are regarded as dangerous solid wastes; however, the methanol, ethanol and toluene in the mixture are all common solvents, and the solvents are separated into substances with high content through rectification, so that waste materials can be changed into valuable materials. The separation of the mixture by distillation is realized by depending on the relative volatilities of the components, and the larger the relative volatilities are, the easier the separation is, however, for some mixtures, the relative volatilities of the components are close to or equal to 1, and the separation cannot be realized by the common distillation method, and a special distillation mode is required.
The special rectification modes commonly used at present comprise azeotropic rectification, extractive rectification, membrane separation, pressure swing rectification, adsorption rectification and the like. Methanol and toluene are common organic solvents in the fields of fine chemical engineering and medicine, and at normal pressure, the methanol and the toluene deviate from Raoult's law to generate positive deviation, so that a minimum azeotrope is formed, and the azeotropic temperature is 63.8 ℃; the mass fraction of methanol in the azeotrope was 69% and the mass fraction of toluene was 31%. The conventional common rectification method is difficult to separate effectively; in actual production, if a continuous azeotropic rectification flow is adopted, two sets of rectification towers and one set of water extraction tower are required to be arranged for rectifying and separating methanol and toluene aiming at the problem of separating the methanol and toluene azeotrope; but the continuous three-tower process has large treatment capacity, complex device, high automatic control requirement and high investment; if a continuous extraction and rectification process is adopted, two sets of rectification towers, namely an extraction tower and a solvent recovery tower, are required to be arranged; the extraction solvent which is selectable in the extraction distillation is quite large, and the extraction solvent regeneration needs negative pressure distillation because of the large extraction solvent ratio, so that the energy consumption of the device is relatively high, and the process is relatively complex. Aiming at the problem of separation of ethanol, toluene and water mixtures, as toluene and ethanol generate homogeneous azeotropy (the azeotropic temperature is 76.7 ℃, the azeotropic composition contains ethanol 68%), toluene and water generate heterogeneous water azeotropy (the azeotropic temperature is 84.1 ℃, the azeotropic composition contains water 13.5%), and simultaneously toluene and ethanol and water also generate ternary heterogeneous azeotrope (the azeotropic temperature is 74.4 ℃, and the azeotropic composition toluene-ethanol-water=51-37-12); if a continuous azeotropic distillation process is adopted, three rectifying towers, namely an ethanol azeotropic tower, a toluene rectifying tower and an ethanol recovery tower, are required to be arranged for separating the ethanol-toluene-water mixture, and a phase separator is arranged at the same time, so that the three-tower combined process has the advantages of large treatment capacity, complex device, high automatic control requirement and high investment; if a continuous extraction and rectification process is adopted, two sets of rectification towers, namely an extraction tower and a solvent recovery tower, are required to be arranged; the extraction solvent which is selectable in the extraction distillation is a large quantity, and the extraction solvent regeneration needs negative pressure distillation because of the large ratio of the extraction distillation solvent, so that the energy consumption of the device is high, and the process is relatively complex. The azeotropic mixture pressurized rectification is to separate methanol, ethanol and toluene by utilizing the azeotropic mixture under different pressure conditions and the azeotropic temperature and component content deviation, the relative volatility of the components in the pressurizing process is reduced, the energy consumption is increased, the high and low heat sources need to be integrated thermally, the process is complex, the temperature and the pressure of the pressurized rectifying tower are relatively high, and the defect of high safety grade exists.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a device and a method for separating a mixture of methanol, ethanol, toluene and water, and aims to solve the technical problems that the existing special rectification mode cannot meet the high-efficiency separation requirement of the mixture of the methanol, the ethanol, the toluene and the water, and the separation equipment is complex and has the defects of insufficient safety.
The first technical scheme provided by the invention is a method for separating a mixture of methanol, ethanol, toluene and water, and the specific technical scheme is as follows:
a process for separating a mixture of methanol, ethanol, toluene and water comprising the steps of:
s1, distilling a material to be separated, and rectifying to obtain methanol-toluene mixed fractions respectively, wherein an ethanol-toluene-water mixture fraction is obtained at the bottom of the tower;
s2, rectifying and cooling the methanol-toluene mixed fraction in the step S1 to obtain an upper oil phase and a lower water phase, and rectifying the oil phase and the water phase after phase separation respectively to obtain a toluene finished product and a methanol finished product;
and S3, rectifying the ethanol-toluene-water mixture fraction in the step S1, cooling and phase-separating the ethanol-toluene-water ternary azeotrope obtained from the top of the tower to obtain an upper oil phase and a lower water phase, and rectifying the phase-separated oil phase and water phase respectively to obtain a toluene finished product and an ethanol finished product correspondingly.
In certain embodiments, the step S1 comprises the steps of:
s11, distilling a material to be separated to obtain a gas-phase material, wherein the gas-phase material comprises a methanol-ethanol-toluene-water mixture;
and S12, rectifying the gas phase material in the step S11, obtaining an ethanol-toluene-water mixture fraction at the bottom of the tower, and condensing the gas phase material at the top of the tower to obtain a methanol-toluene azeotrope fraction.
Further, in step S11, the operation pressure of distillation is 105-110kPa, and the temperature is 65-110 ℃; in the step S12, the bottom pressure of the rectification is 105-110kPa; the temperature of the top of the rectification column is 66-110 ℃, and the temperature of the bottom of the rectification column is 70-115 ℃; the operation reflux ratio of the rectification is 0.1-15.
In certain embodiments, the step S2 includes the steps of:
s21, rectifying the methanol-toluene mixed fraction in the step S1, and obtaining a methanol-toluene azeotrope at the top of the tower;
s22, adding deionized water into the methanol-toluene azeotrope obtained in the step S21 to carry out cooling phase separation to obtain an upper oil phase and a lower water phase, wherein the upper oil phase is crude toluene;
s23, rectifying the crude toluene in the step S22, adding deionized water into a methanol-toluene azeotrope obtained from the top of the tower for cooling and phase separation to obtain an upper oil phase and a lower water phase, rectifying the upper oil phase again, and collecting finished toluene;
s24, rectifying the lower water phase in the step S22 and the lower water phase in the step S23, removing toluene-methanol transition fraction, rectifying again at a reflux ratio of 5-10, and then extracting finished methanol at a reflux ratio of 1-3.
Further, in step S21, the reflux ratio of the methanol-toluene azeotrope obtained by rectification is 1-5; in step S22, the water addition ratio is the overhead: water=0.1-3; in step S23, the operation conditions for extracting the finished toluene are as follows: the temperature of the top of the tower is 110.6 ℃ and the temperature of the bottom of the tower is 115-120 ℃.
In certain embodiments, the step S3 includes the steps of:
s31, rectifying and dehydrating the ethanol-toluene-water mixture fraction in the step S1 to obtain an ethanol-toluene-water mixture fraction with the concentration of less than 50000ppm, and rectifying to obtain an ethanol-toluene-water ternary azeotrope;
s32, carrying out phase separation on the ethanol-toluene-water ternary azeotrope in the step S31 to obtain an upper oil phase and a lower water phase;
s33, rectifying the upper oil phase in the step S32 for a plurality of times until the ethanol and the water are completely separated, and extracting finished toluene;
s34, dehydrating the lower water phase in the step S32 and the lower water phase of the multi-time rectification phase in the step S33, rectifying, extracting ethanol, water and toluene transitional fractions, and extracting finished ethanol from the water phase after layering.
Further, in step S31, the reflux ratio of the ethanol-toluene-water ternary azeotrope obtained by rectification is 1-3; in the step S33, the operation reflux ratio of rectification is 1-5; in step S34, the operation reflux ratio of rectification is 1-10.
The second technical scheme provided by the invention is a device for separating a mixture of methanol, ethanol, toluene and water, and is suitable for the method described in the first technical scheme, and the specific technical scheme is as follows:
including stills, rectifying unit, phase separator, reflux drum, water phase receiving tank, crude toluene receiving tank, transition fraction jar and product jar, the stills with rectifying unit intercommunication, rectifying unit loops through one-level condenser, second grade condenser with the phase separator intercommunication, phase separator still communicates the top of reflux drum the top of water phase receiving tank with crude toluene receiving tank intercommunication, the bottom of reflux drum with rectifying unit intercommunication and through reflux cooler intercommunication the top of transition fraction jar, the top of water phase receiving tank respectively with rectifying unit the top of crude toluene receiving tank the top of transition fraction jar with product jar top intercommunication, the bottom of water phase receiving tank the bottom of crude toluene receiving tank with the bottom of transition fraction jar all with rectifying unit intercommunication.
In some embodiments, the rectification unit comprises a rectification tower and a tower kettle, the number of theoretical plates of the rectification tower is 50-80, the number of theoretical plates of a rectification section is 25-40, the number of theoretical plates of a stripping section is 25-40, and the top of the rectification tower is respectively connected with the bottoms of the first-stage condenser and the reflux tank;
the rectifying tower is characterized in that the tower kettle is arranged at the bottom of the rectifying tower, a reboiler is arranged in the tower kettle, the rectifying tower and the tower kettle are communicated with the distilling kettle, the bottom of the water phase receiving tank, the bottom of the crude toluene receiving tank and the bottom of the transition fraction tank are communicated with the tower kettle, and the bottom of the tower kettle is connected with a tower bottom condenser.
In certain embodiments, the phase separator comprises a phase separation cooler and a phase separation tank which are communicated, the phase separation cooler is connected with the secondary cooler, the upper part of the phase separation tank is communicated with the middle part of the rectifying tower, the top of the reflux tank and the top of the crude toluene receiving tank respectively, and the bottom of the phase separation tank is communicated with the top of the water phase receiving tank.
The invention has the following beneficial effects: the raw materials contain solvents of methanol, ethanol, toluene, water and other small amount of inorganic salt high-boiling impurities, are a byproduct or solid waste of related factories, have different raw material quantity and have large composition variation; removing high-boiling residue from the raw materials by simple distillation, rectifying to obtain a toluene-methanol binary azeotrope at the top of the tower and an ethanol-toluene-water three-component mixture at the bottom of the tower; adding ionized water into the toluene-methanol binary azeotrope, taking water as an extractant, extracting methanol and water in the azeotrope, and rectifying to obtain methanol and toluene products; the ethanol-toluene-water three-component mixture utilizes the characteristic of cooling and phase separation of an ethanol-toluene-water ternary azeotrope, namely, the water content of an oil phase toluene is low after phase separation, the water content of a water phase is high, the water content and the toluene in the ternary azeotrope are separated from a system, and a binary azeotropy is generated by combining the ethanol-toluene, so that an ethanol product is obtained to the maximum extent; after phase separation, the upper layer is rectified to obtain the toluene product, the lower layer is rectified to obtain ethanol-toluene-water fraction, and the ethanol-toluene-water fraction is reused, so that the yield is improved. The method and the device have mild separation conditions, avoid adverse factors such as high temperature and high pressure, improve the safety, have simple separation flow, clear targets, stable quality of separated products, safe and reliable process, low manufacturing cost and considerable economic benefit.
Drawings
FIG. 1 is a schematic diagram of the apparatus for separating a mixture of methanol, ethanol, toluene and water according to the present invention;
the labels in the figures are: r1, distilling still; t1, a rectifying tower; v1, tower kettle; v2, phase separation tank; v3, a reflux tank; v4, a water phase receiving tank; v5, a crude toluene receiving tank; v6, a transition fraction tank; v7, a product tank; e1, a reboiler; e2, a first-stage condenser; e3, a secondary condenser; e4, a phase separation cooler; e5, a reflux cooler; e6, a tower bottom condenser; 1. a raw material inlet; 2. a fraction inlet; 3. a deionized water inlet; 4. a product outlet; 5. an overhead fraction outlet; 6. a bottoms fraction outlet; 7. and a high-boiling material outlet.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
As shown in fig. 1, the raw material or the rectified fraction enters a distillation kettle or a tower kettle through a raw material pump, and batch operation or semi-continuous operation is adopted, which is specifically as follows:
(1) The materials in the distillation kettle R1 are heated by steam; gasifying materials, wherein the operation pressure is 105-110kPa, and the temperature is 65-110 ℃; the gas phase material in the tower kettle V1 enters a rectifying tower T1, and the gas phase material comprises a methanol-ethanol-toluene-water mixture; the non-volatile salts and the organic high-boiling substances obtained at the bottom of the distillation kettle R1 are discharged out of the system from the high-boiling substance outlet 7 while the high-boiling substances are hot;
(2) The methanol-ethanol-toluene-water mixture is a binary and multielement azeotropic system, the homogeneous or heterogeneous azeotropic material composition is eliminated through the addition and subtraction of water, and then rectification separation is carried out, so that a qualified product is finally obtained;
(3) The tower kettle V1 adopts a horizontal tower kettle V1, and materials are heated by a reboiler E1 to implement rectification; the operation pressure at the top of the tower is normal pressure, and the pressure at the bottom of the tower is 105-10kPa; the temperature of the top of the tower is 66-110 ℃, and the temperature of the bottom of the rectifying tower T1 is 70-115 ℃; the gas phase materials at the top of the tower sequentially enter a first-stage condenser E2 and a second-stage condenser E3; the refrigerant of the two-stage condenser adopts circulating water, and condensate enters a reflux tank V3 or a phase separator according to the process requirement; the condensed liquid in the reflux tank V3 is divided into two paths by a reflux pump, one path enters a feeding hole at the top of the rectifying tower T1, and the other path enters a water phase receiving tank V4, a crude toluene receiving tank V5, a transition fraction tank V6 and a product tank V7 after being cooled by a reflux cooler E5; the operation reflux ratio of the rectifying tower T1 is 0.1-15; the number of theoretical plates of the rectifying tower T1 is 50-80, wherein the number of theoretical plates of the rectifying section is 25-40, and the number of theoretical plates of the stripping section is 25-40;
(4) The phase separator is formed by combining a phase separation tank V2, the operation temperature is 20-30 ℃, and the residence time is 0.5-3h; the sources of the phase separator materials are condensate from the top of the tower and liquid extracted from a reflux cooler E5; if the phase separator directly receives condensate at the top of the tower, the phase separation cooler E4 is communicated with the deionized water inlet 3, the condensate can be mixed with water, after being cooled and phase separated, crude toluene in the upper layer oil phase is fed into the reflux tank V3, water, alcohols and a small amount of toluene in the lower layer water phase enter the water phase receiving tank V4, the dehydration mode is total reflux dehydration, the toluene phase is pumped into the top of the rectifying tower T1 through a pump, and the operation reflux ratio of the rectifying tower T1 is theoretically 0; if the phase separator receives the produced liquid from the reflux cooler E5, after the materials are separated by cooling phase, the toluene-containing material in the upper oil phase is fed into a crude toluene receiving tank V5 or returned to the middle feed inlet of a rectifying tower T1, the water-containing material in the lower water phase, alcohols and a small amount of toluene are returned into the middle feed inlet of the rectifying tower T1 or connected to a water-receiving tank V4, the dehydration mode is toluene-ethanol-water ternary azeotropic dehydration, and the reflux ratio of the operation of the rectifying tower T1 is 1-10;
(5) And (3) extracting a rectification product and a fraction, effectively combining the rectification product and a reflux tank V3 through a phase separator to obtain a middle fraction of methanol, ethanol and toluene, and finally obtaining the methanol, ethanol and toluene products with the content of more than 99.5 percent through rectification.
Specifically, the raw materials (which enter the system from a raw material inlet 1) comprise 5-15% of methanol, 20-60% of ethanol, 20-60% of toluene, 0.5-20% of water, and 0.5-3% of other inorganic salts and high-boiling substances; separating a raw material methanol-ethanol-toluene-water mixture, firstly removing heavy components in the raw material by adopting a distillation kettle R1 to prevent the defects of filling materials and a tower kettle V1 from being blocked after the raw material directly enters a rectifying tower T1; in addition, the ethanol-toluene-water mixture fraction and the methanol-toluene azeotrope fraction can directly enter the middle part of the rectifying tower T1 or enter the tower kettle V1 through a raw material pump, and the two fractions do not contain inorganic salts, and are generated in the rectifying separation process, so that the compositions of the two fractions are greatly different according to the process conditions.
Firstly, separating a gas phase solvent in a raw material in a distillation kettle R1 through continuous rectification; feeding the condensate of the gas-phase material at the top of the rectifying tower T1 into a reflux tank V3, refluxing a part of the condensate to the top of the tower through a reflux pump, cooling a part of the condensate, taking the condensate into a receiving tank, and obtaining a methanol-toluene mixed fraction discharged through a tower top fraction outlet 5, wherein the methanol-toluene mixed fraction comprises 69% of methanol and 31% of toluene; the tower bottom material of the rectifying tower T1 is cooled by a tower bottom condenser E6, and a tower bottom pump outputs through a tower bottom fraction outlet 6 to obtain ethanol-toluene-water mixed fraction, wherein the ethanol-toluene-water mixed fraction comprises 20-55% of ethanol, 20-50% of toluene and 1-20% of water; the reflux ratio of the rectification operation is 2-5.
A methanol-toluene mixed fraction which is a binary azeotrope of methanol-toluene and does not contain ethanol and water; the methanol-toluene mixed fraction can directly enter a tower kettle V1 from a fraction inlet 2 through a pump or a receiving tank bottom valve; separating the methanol and toluene azeotrope by adopting a batch rectification mode; the reflux ratio of toluene azeotrope extracted from the batch rectifying tower T1 is controlled to be 1-5, water is required to be added to the extracted azeotrope, and the water adding ratio is the distillate at the top of the tower: water=0.1-3; the azeotrope after water addition is mixed and cooled and then enters a phase separator for phase separation, the upper toluene phase enters a crude toluene receiving tank V5, and the lower water phase returns to the middle part of a rectifying tower T1; until toluene phase separation is finished; a small amount of toluene-methanol transition fraction is extracted and enters a water phase receiving tank V4, the reflux ratio is 5-10, then finished methanol is extracted from the top of the tower at the reflux ratio of 1-3 and enters a product receiving tank, and the methanol product with the content more than 99.5% is output by a product pump; water is obtained at the bottom of the tower.
Crude toluene in the crude toluene receiving tank V5 enters a tower kettle V1; the top of the rectifying tower T1 is used for extracting a methanol-toluene mixture, and a transition fraction enters a water phase receiving tank V4 or a crude toluene receiving tank V5 to extract finished toluene operation conditions; the temperature of the top of the tower is 110.6 ℃, the temperature of the bottom of the tower is 115-120 ℃, and the reflux ratio is 1-10; the extracted finished toluene enters a receiving tank and is output by a product pump to be the product toluene, and the purity of the toluene is more than 99.5 percent;
the tower bottom material of the rectifying tower T1 is output by a tower bottom pump to obtain an ethanol-toluene-water mixed fraction material, and the ethanol-toluene-water mixed fraction material enters a tower kettle V1; separating the ternary azeotrope of ethanol and m-benzene and water by adopting a batch rectification mode; the reflux ratio of the toluene ternary azeotrope extracted by the batch rectifying tower T1 is controlled to be 1-5; determining the material in the phase separator according to the toluene and water content in the material; the extracted ternary azeotrope is divided into two layers after being cooled again by a reflux cooler E5 and a phase separator, the upper toluene phase can firstly return to a rectifying tower T1 or a crude toluene receiving tank V5 is removed, and the lower water phase receiving tank V4 or the rectifying tower T1 is returned; if the water content in the material is less, the ethanol content is more than 80 percent, and the toluene content is 5 to 15 percent, the dehydration can be carried out in a total reflux mode; namely, after condensate on the top of the tower directly enters a phase separator for cooling and phase separation, toluene on the upper layer of oil phase enters a reflux tank V3, is pumped into the top of the tower through a pump reflux pump, and water on the lower layer enters a water phase receiving tank V4; stopping total reflux dehydration until the phase separation interface of the phase separation tank V2 disappears, and changing the operation into normal rectification operation, wherein the operation reflux ratio is 1-10; and (3) rectifying to extract ethanol, water and toluene-ethanol transition fraction, feeding the ethanol and toluene-ethanol transition fraction into a transition fraction receiving tank, finally extracting finished ethanol, feeding the finished ethanol into a product tank V7, and outputting an ethanol product with the content of more than 99.5% through a product pump.
The materials in the aqueous ethanol receiving tank (water phase receiving tank V4) are lower water phase materials after ternary azeotrope phase separation, and the compositions of the lower water phase materials are 53% of ethanol, 11% of toluene and 36% of water; the materials enter a tower kettle V1 through a raw material pump or directly for batch distillation; the ternary azeotrope of ethanol-toluene-water extracted from the top of the tower is fed into a reflux tank V3, the mixture of ethanol-toluene-water extracted from the reflux pump is fed into a transition fraction tank V6, the material composition is 78% of ethanol, 15% of toluene and 3-7% of water, water is obtained from the bottom of the tower, the solvent content (ethanol and toluene) is less than 0.05%, and the mixture is discharged from the system through a pump at the bottom of the tower;
the materials in the crude product receiving tank (crude toluene tank) are upper oil phase materials after ternary azeotrope phase separation, and the components are 15% of ethanol, 84% of toluene and 1% of water; the materials enter a tower kettle V1 through a raw material pump or directly, and ionized water is added into the tower kettle V1, wherein the proportion of the ionized water is 10-15% of that of the raw materials; through batch rectification, azeotrope extracted from the top of the tower is fed into a reflux tank V3, cooled by a reflux pump and a cooler and fed into a phase separator, the lower water phase is fed into a water phase receiving tank V4, the materials comprise 53% of ethanol, 11% of toluene and 36% of water, the upper toluene is returned into a rectifying tower T1 until the ethanol and the water are finished, a small amount of toluene transition fraction is fed into a toluene-ethanol transition fraction tank V6, and finally finished toluene is fed into a product tank V7, and toluene products with the content of more than 99.5% are output by a product pump.
Example 1
The raw material adopted in the embodiment is 1# raw material, impurities are removed by pretreatment distillation, toluene-methanol azeotrope fraction is obtained from the top of a rectifying tower T1, and ethanol-toluene-water mixed fraction is obtained from the bottom of the rectifying tower T1, and the rough distillation process is as follows:
the raw materials or the rectification fraction enter a distillation kettle R1 or a tower kettle V1 through a raw material pump, and batch or semi-continuous operation is adopted; the materials in the distillation kettle R1 are heated by steam; gasifying materials, wherein the operation pressure is 105-110kPa, and the temperature is 65-110 ℃; the gas phase material in the kettle enters a middle feed inlet of a rectifying tower T1, and the gas phase material comprises a methanol-ethanol-toluene-water mixture; the bottom of the distillation kettle R1 is provided with nonvolatile salts and organic high-boiling substances, and the non-volatile salts and the organic high-boiling substances are discharged out of the system when the non-volatile salts and the organic high-boiling substances are hot; the material in the tower kettle V1 is heated by a reboiler E1, and rectification is implemented; the operation pressure at the top of the tower is normal pressure, and the pressure at the bottom of the tower is 105-110kPa; the temperature of the top of the tower is 64 ℃, and the temperature of the bottom of the rectifying tower T1 is 70-80 ℃; the gas phase materials at the top of the tower sequentially enter a first-stage condenser E2 and a second-stage condenser E3; the refrigerant of the two-stage condenser adopts circulating water, and condensate enters a reflux tank V3; one path of the water is output by a reflux pump and enters a feeding port at the top of the rectifying tower T1, and the other path of the water is cooled by a reflux cooler E5 and then enters a water phase receiving tank V4; the operation reflux ratio of the rectifying tower T1 is 2-3, the theoretical plate number is 60, wherein the theoretical plate number of the rectifying section is 30, and the theoretical plate number of the stripping section is 30; rectifying to obtain methanol-toluene azeotrope fraction at the top of the tower; the ethanol-toluene-water mixture fraction is obtained at the bottom of the column.
The composition of the 1# raw material is shown in table 1, and the composition of the fraction obtained by the 1# raw material crude distillation is shown in table 2.
2. Separation of methanol-toluene azeotrope fractions:
the methanol-toluene azeotrope fraction is separated, and the binary azeotrope separation is completed by using the rectification system T1 of the rectification tower of the device through twice rectification.
Firstly, methanol-toluene azeotrope fraction enters a tower kettle V1, reflux ratio is operated to be 1-5, the azeotrope obtained at the tower top is added with deionized water, the mixture is layered by a phase separator, and crude toluene in an upper oil phase enters a crude toluene receiving tank V5; the lower water phase enters a middle feed inlet of a rectifying tower T1, and the water adding ratio is as follows: fraction/water=1/0.5-2; after layering, a small amount of transition fraction is extracted and enters a water phase receiving tank V4, then finished methanol is extracted and enters a product tank V7 according to a reflux ratio of 1-3, and the finished methanol is output by a product pump P4, wherein the methanol content is more than 99.5%, and the water content is less than 0.05%;
the crude toluene fraction enters a tower kettle V1, reflux ratio is operated to be 1-5, azeotrope obtained at the tower top is added with deionized water, the mixture is layered by a phase separator, the upper-layer oil phase toluene enters a middle feeding port of a rectifying tower T1, the lower-layer methanol-containing water phase enters a water phase receiving tank V4, and the water adding ratio is as follows: produced fraction/water=1/0.1-1; after layering, a small amount of transition fraction is extracted and enters a crude toluene receiving tank V5, then finished toluene is extracted and enters a product tank V7 according to a reflux ratio of 1-3, and the finished toluene is output by a product pump, wherein the toluene content is more than 99.5%, and the water content is less than 0.05%;
3. ethanol-toluene-water mixed fraction separation:
(1) If the water content of the ethanol-toluene-water mixed fraction after the rough distillation is higher, the ethanol-toluene-water mixed fraction can be treated by a rectifying unit, the ethanol-toluene-water mixed fraction with less water content is obtained at the top of the tower after the rectification, and water is obtained at the bottom of the tower.
(2) The ethanol-toluene-water mixed fraction with less water content is sent to a rectification unit for treatment, the toluene is extracted at the earlier stage, the ternary azeotrope extracted from the top of the tower is cooled and then sent to a phase separator, the toluene in the upper layer is separated and sent to a crude toluene receiving tank V5, the water phase in the lower layer is separated and returned to a feeding port in the middle part of a rectification tower T1, and the reflux ratio is 1-3; the middle stage is dehydration, ternary azeotrope extracted from the top of the tower is cooled and then enters a phase separator, toluene in the upper oil phase is separated out and returns to a feeding port in the middle part of a rectifying tower T1, water in the lower layer is separated out and enters a water phase receiving tank V4, and the reflux ratio is 1-3; and the later period is the extraction product, the middle fraction of ethanol-toluene extracted from the top of the tower enters a crude toluene receiving tank V5, then the ethanol product is received and enters a product tank V7, the ethanol product is output through a product pump, and the ethanol content is more than 99.5% and the water content is less than 0.05%.
(3) The separated oil phase toluene fraction enters a rectifying unit for treatment, water stratification is added in the rectifying implementation process, water and ethanol in the system can be removed in a total reflux mode, or water and ethanol in the system can be removed in a ternary azeotrope cooling layering mode, the reflux ratio is operated to be 1-5, and the ethanol-toluene middle fraction is extracted from the top of the tower and enters a transition fraction receiving tank; and finally, the finished toluene is extracted into a product tank V7 according to the operation reflux ratio of 0-1, and is output by a product pump, wherein the toluene content is more than 99.5%, and the water content is less than 0.05%.
Example 2
In the embodiment, the raw material No. 2 is adopted, the impurities are removed by pretreatment distillation, the top of a rectifying tower T1 is used for obtaining toluene-methanol azeotrope fraction, and the bottom of the rectifying tower T1 is used for obtaining ethanol-toluene-water mixed fraction; the procedure is the same as in embodiment 1 and will not be described in detail;
the composition of the 2# raw material is shown in table 1, the composition of the fraction obtained by the 2# raw material crude distillation is shown in table 2,
the separation of the methanol-toluene azeotrope is carried out in the same manner as in example 1 and will not be described in detail;
after the raw material No. 2 is roughly steamed, an ethanol-toluene-water mixed fraction is obtained at the bottom of the tower, and the separation process is the same as the ethanol-toluene-water mixed fraction rectification method in the embodiment 1; because the water content is lower, a proper amount of water can be added to promote layering when the ternary azeotrope at the top of the tower enters the phase separator, and finally ethanol and toluene products with the content of more than 99.5% are obtained, wherein the ethanol content of the products is larger than that of toluene.
Example 3
In the embodiment, 3# raw material is adopted, impurities are removed through pretreatment distillation, toluene-methanol azeotrope fraction is obtained at the top of a rectifying tower T1, and ethanol-toluene-water mixed fraction is obtained at the bottom of the rectifying tower; the procedure was the same as in example 1;
the composition of the 3# raw material is shown in table 1, the composition of the fraction obtained by the 3# raw material crude distillation is shown in table 2,
the separation of the methanol-toluene azeotrope is carried out in the same way as in example 1, and is not repeated;
after the 3# material is roughly distilled, the ethanol-toluene-water mixed fraction is obtained at the bottom of the tower, and the separation process is the same as the ethanol-toluene-water mixed fraction rectification method in the example 1; because of higher water content, the mixed fraction can be roughly steamed and dehydrated to obtain a ternary mixture with water content of 3-5%, then rectification separation is carried out, and the ternary azeotrope at the top of the tower enters a phase separator for direct layering, so that the dehydration time is shortened, the energy consumption is low, and finally ethanol and toluene products with the content of more than 99.5% are obtained.
Example 4
In the embodiment, the 4# raw material is adopted, the impurities are removed through pretreatment distillation, the top of a rectifying tower T1 is used for obtaining a toluene-methanol azeotrope fraction, and the bottom of the rectifying tower T1 is used for obtaining an ethanol-toluene-water mixed fraction; the procedure was the same as in example 1;
the composition of the 4# raw material is shown in table 1, the composition of the fraction obtained by the 4# raw material crude distillation is shown in table 2,
the separation process of the methanol-toluene azeotrope of the crude distillation material at the top of the tower and the separation process of the ethanol-toluene-water mixed fraction at the bottom of the tower are the same as those of the embodiment 1, and finally the methanol, ethanol and toluene products with the content of more than 99.5% are obtained, and the details are omitted.
Example 5
In the embodiment, a No. 5 raw material is adopted, impurities are removed through pretreatment distillation, a toluene-methanol azeotrope fraction is obtained at the top of a rectifying tower T1, and an ethanol-toluene-water mixed fraction is obtained at the bottom of the rectifying tower; the procedure was the same as in example 1;
the composition of the 5# raw material is shown in table 1, the composition of the fraction obtained by the 5# raw material crude distillation is shown in table 2,
the separation of the methanol-toluene azeotrope is carried out in the same way as in example 1, and is not repeated;
after the No. 5 material is roughly steamed, an ethanol-toluene-water mixed fraction is obtained at the bottom of the tower, and the separation process is the same as the rectification method of the ethanol-toluene-water mixed fraction in the embodiment 3; because of higher water content, the mixed fraction can be roughly steamed and dehydrated to obtain a ternary mixture with water content of 3-5%, then rectification separation is carried out, and the ternary azeotrope at the top of the tower enters a phase separator for direct layering, so that the dehydration time is shortened, the energy consumption is low, and finally ethanol and toluene products with the content of more than 99.5% are obtained.
Example 6
In the embodiment, a No. 6 raw material is adopted, impurities are removed through pretreatment distillation, a toluene-methanol azeotrope fraction is obtained at the top of a rectifying tower T1, and an ethanol-toluene-water mixed fraction is obtained at the bottom of the rectifying tower; the procedure was the same as in example 1;
the composition of the 6# raw material is shown in table 1, the composition of the fraction obtained by the 6# raw material crude distillation is shown in table 2,
the separation process of the methanol-toluene azeotrope of the crude distillation material at the top of the tower and the separation process of the ethanol-toluene-water mixed fraction at the bottom of the tower are the same as those of the embodiment 4, and finally the methanol, ethanol and toluene products with the content of more than 99.5% are obtained, and the details are omitted.
Example 7
In the embodiment, the No. 7 raw material is adopted, the impurities are removed by pretreatment distillation, the top of a rectifying tower T1 is used for obtaining a toluene-methanol azeotrope fraction, and the bottom of the rectifying tower is used for obtaining an ethanol-toluene-water mixed fraction; the procedure was the same as in example 1;
the composition of the 7# raw material is shown in table 1, the composition of the fraction obtained by the 7# raw material crude distillation is shown in table 2,
the separation of the methanol-toluene azeotrope is carried out in the same way as in example 1, and is not repeated;
after the 7# material is roughly distilled, an ethanol-toluene-water mixed fraction is obtained at the bottom of the tower, and the separation process is the same as the distillation method of the ethanol-toluene-water mixed fraction in the example 1; because of higher water content, the mixed fraction can be roughly steamed and dehydrated to obtain a ternary mixture with water content of 3-5%, then rectification separation is carried out, and the ternary azeotrope at the top of the tower enters a phase separator for direct layering, so that the dehydration time is shortened, the energy consumption is low, and finally ethanol and toluene products with the content of more than 99.5% are obtained.
Example 8
In the embodiment, the No. 8 raw material is adopted, the impurities are removed by pretreatment distillation, the top of a rectifying tower T1 is used for obtaining a toluene-methanol azeotrope fraction, and the bottom of the rectifying tower is used for obtaining an ethanol-toluene-water mixed fraction; the procedure was the same as in example 1;
the composition of the 8# raw material is shown in table 1, the composition of the fraction obtained by the 8# raw material crude distillation is shown in table 2,
the separation of the methanol-toluene azeotrope is carried out in the same way as in example 1, and is not repeated;
after the material 8# is roughly steamed, an ethanol-toluene-water mixed fraction is obtained at the bottom of the tower, and the separation process is the same as the rectification method of the ethanol-toluene-water mixed fraction in the embodiment 1; because the water content is close to the ternary azeotropic composition, rectification separation is directly carried out, and the ternary azeotrope at the top of the tower enters a phase separator to be directly layered, the dehydration time is longer than that of the embodiment 7, the comprehensive energy consumption is basically the same as that of the embodiment 7, and finally ethanol and toluene products with the content of more than 99.5% are obtained.
TABLE 1 raw materials composition Table
TABLE 2 composition of crude distilled components
The above preferred embodiments of the present invention are not limited to the above examples, and the present invention is not limited to the above examples, but can be modified, added or replaced by those skilled in the art within the spirit and scope of the present invention.
Claims (10)
1. A process for separating a mixture of methanol, ethanol, toluene and water comprising the steps of:
s1, distilling a material to be separated, and rectifying to obtain methanol-toluene mixed fractions respectively, wherein an ethanol-toluene-water mixture fraction is obtained at the bottom of the tower;
s2, rectifying and cooling the methanol-toluene mixed fraction in the step S1 to obtain an upper oil phase and a lower water phase, and rectifying the oil phase and the water phase after phase separation respectively to obtain a toluene finished product and a methanol finished product;
and S3, rectifying the ethanol-toluene-water mixture fraction in the step S1, cooling and phase-separating the ethanol-toluene-water ternary azeotrope obtained from the top of the tower to obtain an upper oil phase and a lower water phase, and rectifying the phase-separated oil phase and water phase respectively to obtain a toluene finished product and an ethanol finished product correspondingly.
2. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 1, wherein said step S1 comprises the steps of:
s11, distilling a material to be separated to obtain a gas-phase material, wherein the gas-phase material comprises a methanol-ethanol-toluene-water mixture;
and S12, rectifying the gas phase material in the step S11, obtaining an ethanol-toluene-water mixture fraction at the bottom of the tower, and condensing the gas phase material at the top of the tower to obtain a methanol-toluene azeotrope fraction.
3. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 2, wherein in step S11, the distillation is operated at a pressure of 105 to 110kPa and a temperature of 65 to 110 ℃; in the step S12, the bottom pressure of the rectification is 105-110kPa; the temperature of the top of the rectification column is 66-110 ℃, and the temperature of the bottom of the rectification column is 70-115 ℃; the operation reflux ratio of the rectification is 0.1-15.
4. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 1, wherein said step S2 comprises the steps of:
s21, rectifying the methanol-toluene mixed fraction in the step S1, and obtaining a methanol-toluene azeotrope at the top of the tower;
s22, adding deionized water into the methanol-toluene azeotrope obtained in the step S21 to carry out cooling phase separation to obtain an upper oil phase and a lower water phase, wherein the upper oil phase is crude toluene;
s23, rectifying the crude toluene in the step S22, adding deionized water into a methanol-toluene azeotrope obtained from the top of the tower for cooling and phase separation to obtain an upper oil phase and a lower water phase, rectifying the upper oil phase again, and collecting finished toluene;
s24, rectifying the lower water phase in the step S22 and the lower water phase in the step S23, removing toluene-methanol transition fraction, rectifying again at a reflux ratio of 5-10, and then extracting finished methanol at a reflux ratio of 1-3.
5. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 4, wherein in step S21, the reflux ratio of the methanol-toluene azeotrope obtained by the rectification is 1 to 5; in step S22, the water addition ratio is the overhead: water=0.1-3; in step S23, the operation conditions for extracting the finished toluene are as follows: the temperature of the top of the tower is 110.6 ℃ and the temperature of the bottom of the tower is 115-120 ℃.
6. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 1, wherein said step S3 comprises the steps of:
s31, rectifying and dehydrating the ethanol-toluene-water mixture fraction in the step S1 to obtain an ethanol-toluene-water mixture fraction with the concentration of less than 50000ppm, and rectifying to obtain an ethanol-toluene-water ternary azeotrope;
s32, carrying out phase separation on the ethanol-toluene-water ternary azeotrope in the step S31 to obtain an upper oil phase and a lower water phase;
s33, rectifying the upper oil phase in the step S32 for a plurality of times until the ethanol and the water are completely separated, and extracting finished toluene;
s34, dehydrating the lower water phase in the step S32 and the lower water phase of the multi-time rectification phase in the step S33, rectifying, extracting ethanol, water and toluene transitional fractions, and extracting finished ethanol from the water phase after layering.
7. The method for separating a mixture of methanol, ethanol, toluene and water according to claim 6, wherein in step S31, the reflux ratio of the ethanol-toluene-water ternary azeotrope obtained by the rectification is 1 to 3; in the step S33, the operation reflux ratio of rectification is 1-5; in step S34, the operation reflux ratio of rectification is 1-10.
8. The device for separating a mixture of methanol, ethanol, toluene and water, based on the method of any one of claims 1-7, characterized by comprising a distillation still (R1), a rectifying unit, a phase separator, a reflux tank (V3), a water phase receiving tank (V4), a crude toluene receiving tank (V5), a transition fraction tank (V6) and a product tank (V7), wherein the distillation still (R1) is in communication with the rectifying unit, the rectifying unit is in communication with the phase separator sequentially through a primary condenser (E2), a secondary condenser, the phase separator is in communication with the top of the reflux tank (V3), the top of the water phase receiving tank (V4) and the crude toluene receiving tank (V5), the bottom of the reflux tank (V3) is in communication with the rectifying unit and is in communication with the top of the transition fraction tank (V6) through a reflux cooler (E5), and the top of the water phase receiving tank (V4) is in communication with the rectifying unit, the top of the toluene receiving tank (V5), the top of the transition fraction tank (V6) and the bottom of the crude toluene receiving tank (V6) are in communication with the top of the rectifying unit (V6).
9. The device for separating a mixture of methanol, ethanol, toluene and water according to claim 8, wherein the rectifying unit comprises a rectifying tower (T1) and a tower kettle (V1), the theoretical plate number of the rectifying tower (T1) is 50-80, the theoretical plate number of the rectifying section is 25-40, the theoretical plate number of the stripping section is 25-40, and the top of the rectifying tower (T1) is respectively connected with the first-stage condenser (E2) and the bottom of the reflux tank (V3);
the rectifying tower is characterized in that the tower kettle (V1) is arranged at the bottom of the rectifying tower (T1), a reboiler (E1) is arranged in the tower kettle (V1), the rectifying tower (T1) and the tower kettle (V1) are communicated with the distilling kettle (R1), the bottom of the water phase receiving tank (V4), the bottom of the crude toluene receiving tank (V5) and the bottom of the transition fraction tank (V6) are communicated with the tower kettle (V1), and the bottom of the tower kettle (V1) is connected with a tower bottom condenser (E6).
10. The device for separating a mixture of methanol, ethanol, toluene and water according to claim 8, wherein the phase separator comprises a phase separation cooler (E4) and a phase separation tank (V2) which are communicated, the phase separation cooler (E4) is connected with the secondary cooler, the upper part of the phase separation tank (V2) is communicated with the middle part of the rectifying tower (T1), the top part of the reflux tank (V3) and the top part of the crude toluene receiving tank (V5) respectively, and the bottom part of the phase separation tank (V2) is communicated with the top part of the water phase receiving tank (V4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310354161.XA CN116271919A (en) | 2023-04-04 | 2023-04-04 | Device and method for separating mixture of methanol, ethanol, toluene and water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310354161.XA CN116271919A (en) | 2023-04-04 | 2023-04-04 | Device and method for separating mixture of methanol, ethanol, toluene and water |
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| Publication Number | Publication Date |
|---|---|
| CN116271919A true CN116271919A (en) | 2023-06-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310354161.XA Pending CN116271919A (en) | 2023-04-04 | 2023-04-04 | Device and method for separating mixture of methanol, ethanol, toluene and water |
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| Country | Link |
|---|---|
| CN (1) | CN116271919A (en) |
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2023
- 2023-04-04 CN CN202310354161.XA patent/CN116271919A/en active Pending
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