CN110251980B - Device and method for purifying high-quality dioxane from dioxane aqueous solution - Google Patents
Device and method for purifying high-quality dioxane from dioxane aqueous solution Download PDFInfo
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- CN110251980B CN110251980B CN201910322144.1A CN201910322144A CN110251980B CN 110251980 B CN110251980 B CN 110251980B CN 201910322144 A CN201910322144 A CN 201910322144A CN 110251980 B CN110251980 B CN 110251980B
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- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 title claims abstract description 112
- 239000007864 aqueous solution Substances 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000012528 membrane Substances 0.000 claims abstract description 162
- 239000000463 material Substances 0.000 claims abstract description 63
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000243 solution Substances 0.000 claims abstract description 32
- RNHDAKUGFHSZEV-UHFFFAOYSA-N 1,4-dioxane;hydrate Chemical compound O.C1COCCO1 RNHDAKUGFHSZEV-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000007788 liquid Substances 0.000 claims description 40
- 238000010992 reflux Methods 0.000 claims description 20
- 239000011148 porous material Substances 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 12
- 239000000047 product Substances 0.000 claims description 7
- 239000012466 permeate Substances 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 238000000746 purification Methods 0.000 claims 5
- 238000000926 separation method Methods 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 abstract description 2
- 230000000704 physical effect Effects 0.000 abstract 1
- 238000004821 distillation Methods 0.000 description 9
- 229920005906 polyester polyol Polymers 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000002808 molecular sieve Substances 0.000 description 6
- 238000005373 pervaporation Methods 0.000 description 6
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 6
- 239000002699 waste material Substances 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 229920002635 polyurethane Polymers 0.000 description 4
- 239000004814 polyurethane Substances 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 3
- 229920005862 polyol Polymers 0.000 description 3
- 150000003077 polyols Chemical class 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000005886 esterification reaction Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000006068 polycondensation reaction Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 238000012271 agricultural production Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000000010 aprotic solvent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 229940127554 medical product Drugs 0.000 description 1
- -1 medical products Substances 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 235000013599 spices Nutrition 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/364—Membrane distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/366—Apparatus therefor
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/02—1,2-Dioxanes; Hydrogenated 1,2-dioxanes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a device and a method for purifying high-grade dioxane from a dioxane aqueous solution, wherein the device comprises a membrane distiller, two groups of rectifying towers, a pressure pump feed mixer, a pressure pump, a feed preheater and a steam condenser; the method for purifying the high-grade dioxane by using the device comprises the steps of rectifying the dioxane aqueous solution to be treated by a first rectifying tower, extracting the preconcentrated dioxane-water material from the first rectifying tower to a pressure pump feeding mixer to be mixed with a circulating material, then extracting the mixture, pressurizing by a pressure pump, then extracting to a feeding preheater, preheating and then feeding to a membrane distiller; feeding the concentrated solution extracted by the membrane distiller into a second rectifying tower for rectification, and extracting a high-purity dioxane product from the second rectifying tower through a reboiler of the second rectifying tower; the invention relates to a technical scheme for carrying out azeotropic physical property separation by introducing a membrane distiller through a device for purifying high-grade dioxane from a dioxane aqueous solution, which is a novel environment-friendly water treatment technology.
Description
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a device and a method for purifying high-quality dioxane from a dioxane aqueous solution.
Background
Polyester polyol is an important raw material for synthesizing polyurethane, plays a role of a flexible soft segment in polyurethane synthesis, is endowed with the characteristics of high strength, tear resistance, wear resistance and the like due to the unique molecular structure in the polyurethane, is rapidly developed in recent years based on the unique properties, and is widely applied to various fields, such as aerospace, sports, railways, buildings, daily life, industrial and agricultural production, medicine and the like. Just because of the large-area expansion of the application field of polyurethane, polyester polyol has huge market space and has considerable demand and great research value.
The polyester polyol is a hydroxyl-terminated polyester generally prepared by esterification and polycondensation of a polyol and an organic dicarboxylic acid (anhydride) or polymerization of the polyol and lactone, wherein the commonly used polyol is ethylene glycol, and the ethylene glycol is subjected to polycondensation reaction under the action of a catalyst in an esterification reaction kettle to generate dioxane. Dioxane and water form an azeotrope, a certain amount of waste gas is generated by a cooling separation and incineration method which are commonly used in industry, and the treatment method has the problems of accumulation of byproducts, resource waste, environmental pollution and the like.
Dioxane is an aprotic solvent commonly used in industrial agriculture, is mainly used for the production of solvents, emulsifiers, detergents and the like, can be used for producing solvents of pesticides, medical products, dyes, cellulose acetate, resins, vegetable oils, mineral oil and the like, and is also used in the production processes of paints, varnishes, plasticizers, wetting agents, spices and the like.
The dioxane and the water form an azeotrope, the conventional treatment method is to add an entrainer to destroy the azeotrope of the dioxane and the water to form a new binary azeotrope, and then extract the entrainer from the new binary azeotrope by a pressure swing method for recycling, but the method has the problems of two-tower rectification, huge energy consumption in the rectification operation process, lack of an environment-friendly and efficient entrainer and is not widely used in industry.
It has been reported in the literature that a dioxane-water mixture is separated by pervaporation, but pervaporation still contains a certain amount of dioxane in water permeating a membrane by using the principle of dissolution and diffusion, and the permeated water cannot be directly discharged and still needs further treatment.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a device and a method for purifying high-grade dioxane from a dioxane aqueous solution aiming at the technical problem that the dioxane aqueous solution is difficult to treat in a polyester polyol production process.
The technical scheme is as follows: the invention relates to a device for purifying high-grade dioxane from a dioxane aqueous solution, which comprises a membrane distiller, two groups of rectifying towers, a booster pump feed mixer, a booster pump, a feed preheater and a steam condenser, wherein the membrane distiller is connected with the two groups of rectifying towers;
the membrane distiller comprises a membrane distiller cylinder, a membrane component, an orifice plate and an upper end enclosure; the membrane distiller comprises a membrane distiller cylinder and is characterized in that a membrane assembly is arranged inside the membrane distiller cylinder, the tops of the membrane assembly are connected through a plurality of through holes arranged on a pore plate, an upper end enclosure is mounted at the top of the membrane distiller cylinder, a steam discharge port is formed in the side surface of the upper end enclosure, and the bottom of the membrane distiller cylinder is sealed and is respectively provided with a gas-liquid mixing feed port and a concentrated liquid outlet; the two groups of rectifying towers comprise a first rectifying tower and a second rectifying tower, the first rectifying tower is provided with a feed liquid feed inlet to be treated and a reflux material feed inlet, the bottom of the first rectifying tower is provided with a first rectifying tower reboiler, the top of the first rectifying tower is provided with a steam discharge port and a tower kettle material discharge port, the second rectifying tower is provided with a concentrated dioxane aqueous solution feed inlet and a reflux material feed inlet, the bottom of the second rectifying tower is provided with a second rectifying tower reboiler, and the top of the second rectifying tower is provided with a steam discharge port and a tower kettle material discharge port;
the steam discharge hole of the first rectifying tower is connected with the feed inlet of a pressure pump feed mixer, the discharge hole of the pressure pump feed mixer is sequentially connected with a pressure pump and a feed preheater, the discharge hole of the feed preheater is connected with the gas-liquid mixing feed inlet of a membrane distiller, the steam discharge hole of the membrane distiller is connected with the feed inlet of a steam condenser, the discharge hole of the steam condenser is connected with the reflux material feed inlet of the first rectifying tower, the tower kettle material discharge hole of the first rectifying tower is connected with a reboiler of the first rectifying tower, the concentrated solution liquid outlet of the membrane distiller is connected with the concentrated dioxane aqueous solution feed inlet of the second rectifying tower, the reflux material feed inlet of the second rectifying tower is connected with the discharge hole of a condenser of the second rectifying tower, and the steam discharge hole at the top of the tower is respectively connected with the circulating material feed inlet of the second rectifying tower condenser and the pressure pump feed mixer, and a tower kettle material discharge port of the second rectifying tower is connected with a second rectifying tower reboiler.
Preferably, the membrane module is a special inorganic molecular sieve pervaporation membrane module.
Preferably, the membrane module is a silico-aluminum molecular sieve.
Preferably, the membrane distiller cylinder, the upper end enclosure and the pore plate are in sealed connection through flanges, a gas-liquid mixing feed inlet of the membrane distiller is connected with the membrane distiller cylinder through a flange, a steam discharge outlet of the membrane distiller is connected with the upper end enclosure through a flange, and a concentrated solution outlet is fixed below the membrane distiller cylinder.
A process for purifying good grade dioxane from an aqueous solution of dioxane using the apparatus described above, comprising the steps of:
1) introducing a dioxane aqueous solution to be treated into a first rectifying tower through a feed inlet of a feed liquid to be treated of the first rectifying tower, separating the dioxane aqueous solution to be treated through gas-liquid mass transfer in the first rectifying tower, extracting a preconcentrated dioxane-water material from a steam discharge port of the first rectifying tower, and extracting qualified water from a material discharge port of a tower kettle of the first rectifying tower through a reboiler of the first rectifying tower; wherein, the pre-concentrated dioxane-water material is extracted to a pressure pump feeding mixer to be mixed with the circulating material, then is extracted, is pressurized by a pressure pump and then is extracted to a feeding preheater, and enters a membrane distiller from a gas-liquid mixing feeding port of the membrane distiller after being preheated;
2) in a membrane distiller, the preconcentrated dioxane-water material is fully contacted with a membrane component, water molecules dissolved with a small amount of dioxane are preferentially adsorbed on the surface of the membrane component, permeate through the membrane under the pushing of the partial pressure difference of water vapor on two sides of the membrane component, are vaporized into water vapor on the permeation side of the membrane, and are extracted through a vapor outlet of the membrane distiller; the partially dehydrated concentrated solution is extracted from the feed side of the membrane module through a concentrated solution outlet; steam extracted from a steam outlet of the membrane distiller is cooled by a steam condenser and then returns to a reflux material inlet of the first rectifying tower to be used as reflux liquid of the first rectifying tower; the concentrated solution extracted from the concentrated solution outlet of the membrane distiller enters a second rectifying tower through a concentrated dioxane aqueous solution feed inlet of the second rectifying tower;
3) rectifying the concentrated solution extracted by the membrane distiller in a second rectifying tower, extracting steam close to azeotropy from a steam outlet at the top of the second rectifying tower, and extracting a high-purity dioxane product from a material outlet at the bottom of the second rectifying tower through a reboiler of the second rectifying tower;
4) the vapor which is extracted from the top of the second rectifying tower and is close to the azeotrope is controlled by a valve component, and part of the vapor is extracted to a feed mixer of a pressure pump and enters a system as a circulating material; the other part of the mixed gas is cooled by a second rectifying tower condenser and then flows back to the tower kettle of the second rectifying tower.
Preferably, the membrane module side of the first rectifying tower, the second rectifying tower and the membrane distiller are all operated under normal pressure.
Preferably, the outlet pressure of the pressurizing pump is 0.2-1.0 MPa.
Preferably, the outlet pressure of the pressurizing pump is 0.3-0.5 MPa.
Preferably, the mass fraction of the dioxane in the preconcentrate material at the top of the first rectifying tower is 45-80%; and in the steam extracted from the top of the second rectifying tower, the mass fraction of the dioxane is 80-95%.
Preferably, the membrane module and orifice plate combination has a dioxane rejection of 85% to 92%.
Has the advantages that: (1) according to the invention, a treatment process method of coupling membrane distillation and common rectification is used for treating the dioxane aqueous solution existing in the polyester polyol production process, the first rectifying tower, the second rectifying tower and the membrane distiller are used in combination, qualified water is obtained through the first rectifying tower, and a high-purity dioxane product is obtained through the second rectifying tower;
(2) compared with the treatment method of the dioxane aqueous solution in the prior art, the technical scheme of the invention adopts an incineration method to treat the dioxane wastewater, and the incineration of the dioxane wastewater can generate a large amount of waste gas to pollute the air and has the problems of byproduct accumulation, resource waste and the like; compared with the method, the method for purifying the high-grade dioxane from the dioxane aqueous solution can effectively separate the high-purity dioxane to be used as a byproduct of a polyester polyol production process, and can improve considerable economic benefit for the polyester polyol production process;
(3) the membrane distiller device comprises a membrane distiller cylinder, a membrane component, a pore plate and an upper end enclosure, wherein the membrane component is arranged inside the membrane distiller cylinder, the top of the membrane component is connected through a plurality of through holes arranged on the pore plate, the upper end enclosure is arranged at the top of the membrane distiller cylinder, a steam discharge hole is formed in the side surface of the upper end enclosure, and the bottom of the membrane distiller cylinder is sealed and is respectively provided with a gas-liquid mixed feed inlet and a concentrated liquid outlet; the membrane distiller used in the invention has the advantages of simple structure, good sealing effect, convenient operation, high mass transfer efficiency, capability of being made into modular equipment, good industrial popularization prospect and high economic benefit;
(4) the invention provides a technical scheme for introducing a membrane distiller to carry out azeotropic physical separation in a process method for purifying high-grade dioxane from a dioxane aqueous solution, which utilizes a membrane component in the membrane distiller to fully contact a preconcentrated dioxane-water material with the membrane component, water molecules dissolved with a small amount of dioxane are preferentially adsorbed on the surface of the membrane component, permeate through a membrane under the pushing of partial pressure difference of water vapor on two sides of the membrane component, vaporize into water vapor on the permeation side of the membrane, are extracted through a vapor discharge port of the membrane distiller, and a partially dehydrated concentrated solution enters a second rectifying tower through a concentrated solution outlet of the membrane distiller, so that the mass fraction of the dioxane in the dioxane-water material is improved by the membrane distiller, and qualified water is extracted through the vapor extracted from the vapor discharge port of the membrane distiller by entering a first rectifying tower reboiler, the qualified water in the dioxane aqueous solution is processed to meet the discharge standard, and the process method has the advantages of environmental protection, energy conservation, high yield, good stability, simple and convenient operation and the like, and is a novel environment-friendly water treatment technology.
Drawings
FIG. 1 is a schematic view of the apparatus and process of the present invention.
The system comprises a pressure pump, a feed mixer, a pressure pump, a feed preheater, a pressure pump, a pressure; a-feed liquid to be treated, b-preconcentrate material, c-feed liquid after mixing, d-qualified water, e-gas-liquid mixed feeding after heating, f-steam condensate, g-concentrated dioxane aqueous solution, h-steam, i-cycle material and j-high-purity dioxane product.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the embodiments.
Example 1: a device for purifying high-grade dioxane from a dioxane aqueous solution comprises a membrane distiller 6, two groups of rectifying towers, a booster pump feed mixer 1, a booster pump 3, a feed preheater 4 and a steam condenser 13;
the membrane distiller 6 comprises a membrane distiller cylinder, a membrane component 7, a pore plate 8 and an upper end enclosure 9; the membrane distiller cylinder is internally provided with a membrane component 7, the membrane component 7 is a special inorganic molecular sieve pervaporation membrane component, can be preferably a silicon-aluminum molecular sieve, a plurality of through holes are uniformly arranged on the pore plate 8, the top of the membrane component passes through the through holes and is fixed with the pore plate 8 through bolts, the top of the membrane distiller cylinder body is provided with an upper seal head 9, the membrane distiller cylinder body, the upper seal head 9 and the pore plate 8 are hermetically connected through flanges, the side surface of the upper end enclosure 9 is provided with a steam discharge port 11, the bottom of the cylinder body of the membrane distiller is sealed and is respectively provided with a gas-liquid mixing feed port 10 and a concentrated solution outlet 12, the gas-liquid mixing feed inlet 10 of the membrane distiller 6 is connected with the barrel body of the membrane distiller through a flange, a steam discharge port 11 of the membrane distiller 6 is connected with an upper end enclosure through a flange, and a concentrated solution outlet 12 is fixed below a barrel of the membrane distiller; the two groups of rectifying towers comprise a first rectifying tower 2 and a second rectifying tower 14, the first rectifying tower 2 is provided with a feed liquid feed inlet to be treated and a reflux material feed inlet, the bottom of the first rectifying tower is provided with a first rectifying tower reboiler, the top of the first rectifying tower is provided with a steam discharge port and a tower kettle material discharge port, the second rectifying tower is provided with a concentrated dioxane aqueous solution feed inlet and a reflux material feed inlet, the bottom of the second rectifying tower is provided with a second rectifying tower reboiler, and the top of the second rectifying tower is provided with a steam discharge port and a tower kettle material discharge port;
the steam discharge hole of the first rectifying tower 2 is connected with the feed inlet of a pressure pump feed mixer 1, the discharge hole of the pressure pump feed mixer 1 is sequentially connected with a pressure pump 3 and a feed preheater 4, the discharge hole of the feed preheater 4 is connected with a gas-liquid mixing feed inlet 10 of a membrane distillation 6, the steam discharge hole 11 of the membrane distillation 6 is connected with a feed inlet of a steam condenser 13, the discharge hole of the steam condenser 13 is connected with a reflux material feed inlet of the first rectifying tower 2, a tower kettle material discharge hole of the first rectifying tower 2 is connected with a first rectifying tower reboiler 5, a concentrated solution outlet 12 of the membrane distillation 6 is connected with a concentrated dioxane aqueous solution feed inlet of a second rectifying tower, a reflux material feed inlet of the second rectifying tower 14 is connected with a discharge hole of a condenser 15 of the second rectifying tower, and a tower top steam discharge hole of the membrane distillation is respectively connected with a condenser 15 of the second rectifying tower and a circulating material feed inlet of the pressure pump feed mixer 1, and a tower kettle material discharge port of the second rectifying tower 14 is connected with a second rectifying tower reboiler 16.
A process for purifying good grade dioxane from an aqueous solution of dioxane using the apparatus described above, comprising the steps of:
1) a dioxane aqueous solution a to be treated enters a first rectifying tower 2 through a feed inlet of a feed liquid to be treated of the first rectifying tower 2, the first rectifying tower 2 is operated under normal pressure, the dioxane aqueous solution a to be treated is separated by gas-liquid mass transfer in the first rectifying tower 2, a preconcentrated dioxane-water material is extracted from a steam discharge port of the first rectifying tower 2, a steam condensate f is extracted, the mass fraction of dioxane is 45-80% in a preconcentrated material at the top of the first rectifying tower, and a material discharge port of a tower kettle of the first rectifying tower 2 is used for extracting qualified water, namely qualified water d, through a first rectifying tower reboiler 5; wherein the pre-concentrated dioxane-water material is extracted after being extracted to a pressure pump feeding mixer 1 to be mixed with a circulating material, the mixed material liquid c is extracted to a feeding preheater 4 after being pressurized by a pressure pump 3, the heated gas-liquid mixed feeding e enters a membrane distiller 6 from a gas-liquid mixed feeding port 10 of the membrane distiller 6 after being preheated, the pressure of an outlet of the pressure pump 3 is 0.2-1.0 MPa, and the pressure of the outlet of the pressure pump 3 is preferably 0.3-0.5 MPa;
2) in a membrane distiller 6, a preconcentrated dioxane-water material is fully contacted with a membrane component 7, water molecules dissolved with a small amount of dioxane are preferentially adsorbed on the surface of the membrane component 7, the membrane component 7 side in the membrane distiller operates at normal pressure, the water molecules penetrate through a membrane under the pushing of the partial pressure difference of water vapor on two sides of the membrane component 7 and are vaporized into water vapor on the membrane permeation side, the water vapor is extracted from a vapor outlet 11 of the membrane distiller 6, and the retention rate of the dioxane in the combination of the membrane component and a pore plate is 85% -92%; the partially dehydrated concentrated solution is extracted from the feed side of the membrane module through a concentrated solution outlet 12; steam extracted from a steam outlet 11 of the membrane distiller 6 is cooled by a steam condenser 13 and then returns to a reflux material inlet of the first rectifying tower 2 to be used as reflux liquid of the first rectifying tower; a concentrated solution, namely a concentrated dioxane aqueous solution g, extracted from a concentrated solution outlet 12 of the membrane distiller enters a second rectifying tower 14 through a concentrated dioxane aqueous solution feed inlet of the second rectifying tower;
3) rectifying the concentrated solution extracted by the membrane distiller 6 in a second rectifying tower 14, wherein the operating environment of the second rectifying tower 14 is normal-pressure operation, the steam h close to azeotropic is extracted from a steam outlet at the top of the second rectifying tower 14, and a high-purity dioxane product j is extracted from a material outlet at the bottom of the second rectifying tower 14 through a reboiler of the second rectifying tower;
4) the vapor h which is extracted from the top of the second rectifying tower and is close to the azeotrope is controlled by a valve component, part of the vapor h is extracted to a pressure pump feeding mixer and enters a system as a circulating material i, and the mass fraction of the dioxane in the vapor extracted from the top of the second rectifying tower 14 is 80-95%; the other part of the mixed gas is cooled by a second rectifying tower condenser and then flows back to the tower kettle of the second rectifying tower.
The specific operation flow in this embodiment is as follows: the membrane distiller 6 is 2500mm in height, 800mm in inner diameter and 5mm in wall thickness, a cavity of a barrel body of the membrane distiller is divided into a cylindrical barrel body and an upper cover of the membrane distiller, the upper part and the lower part are separated by a pore plate 8, and the cylindrical barrel body is divided into a membrane distillation generation section and a steam cache section; wherein the membrane distillation generation section mainly comprises a membrane component 7, and the membrane component 7 comprises 300 groups of silicon-aluminum molecular sieve pervaporation membrane filaments with the inner diameter of 0.8 mm, the wall thickness of 0.5 mm, the pore diameter of 0.25 mu m, the porosity of 0.55 and the length of 2200 mm; the membrane assembly 7 is fixed on the pore plate 8 through bolts; the first rectifying tower 2 with the tower diameter of 0.4m and the tower height of 4m and the second rectifying tower 14 with the tower diameter of 0.8m and the tower height of 6m are respectively operated under normal pressure; the outlet pressure of the booster pump 3 was 4.6MPa, and the membrane module side in the membrane distiller 6 was atmospheric pressure.
The waste liquid to be treated, namely the dioxane aqueous solution a to be treated enters a first rectifying tower 2 at the flow rate of 3600kg/h, wherein the dioxane accounts for 16.67 percent (wt), the water accounts for 83.33 percent (wt), the waste liquid to be treated is pre-separated in the first rectifying tower 2, and the tower kettle collects qualified water d with the dioxane content lower than 50ppm at 3000 kg/h; feeding the pre-concentrated feed b at the top of the first rectifying tower 2 into a pressure pump feed mixer 1 at the speed of 1475.0kg/h (wherein dioxane accounts for 49.7 percent (wt)) to be mixed with a circulating feed i at the flow rate of 686.3kg/h, wherein dioxane accounts for 88 percent (wt) and water accounts for 12 percent (wt), pressurizing the feed c mixed by the feed mixer, feeding the feed c to a feed preheater 4 to preheat to 137 ℃, feeding the feed c into a membrane distiller 6, pushing a large amount of water vapor to enter the other side of the membrane assembly under the partial pressure difference of the water vapor at the two sides of the membrane assembly, and taking out the feed c from a steam outlet 11 at the flow rate of 875.4kg/h, wherein the dioxane content is about 15.3 percent (wt); a concentrated aqueous dioxane solution having a dioxane content of about 93.6 wt% was withdrawn through a concentrated liquid outlet 12 at a flow rate of 1286.4 kg/h; and (3) feeding the concentrated dioxane aqueous solution g into a second rectifying tower 14 for rectification, condensing and extracting 1098.1kg/h of steam h from the top of the second rectifying tower 14, wherein 686.3kg/h is taken as a circulating material i, 411.8kg/h of steam enters a second rectifying tower condenser 15 for condensation and reflux to the second rectifying tower 14, and extracting a high-purity dioxane product j with the purity of 99.95% (wt) from the tower bottom at the flow rate of 600 kg/h.
Example 2: the method for purifying the dioxane with excellent quality from the dioxane aqueous solution in the embodiment is carried out by using the device for purifying the dioxane with excellent quality from the dioxane aqueous solution in the embodiment 1, in the embodiment, the height of the membrane distiller 6 is 2000mm, the inner diameter is 600mm, the wall thickness is 5mm, the cavity of the barrel of the membrane distiller is divided into a cylindrical barrel and an upper cover of the membrane distiller, the upper part and the lower part are separated by a pore plate 8, and the cylindrical barrel is divided into a membrane distillation generation section and a steam buffer section; wherein the membrane distillation generation section mainly comprises a membrane component 7, and the membrane component 7 comprises 240 groups of inorganic molecular sieve pervaporation membrane filaments with the inner diameter of 0.8 mm, the wall thickness of 0.3 mm, the pore diameter of 0.25 mu m, the porosity of 0.5 and the length of 1800 mm; the membrane assembly 7 is fixed on the pore plate 8 through bolts; the first rectifying tower 2 with the tower diameter of 0.5m and the tower height of 4.5m and the second rectifying tower 14 with the tower diameter of 0.5m and the tower height of 5.8m are respectively operated under normal pressure; the outlet pressure of the booster pump 3 was 3.5MPa, and the membrane module side in the membrane distiller was at atmospheric pressure.
The waste liquid to be treated, namely the dioxane aqueous solution a to be treated enters a first rectifying tower 2 at the flow rate of 2500kg/h, wherein the dioxane accounts for 20 percent (wt), the water accounts for 80 percent (wt), the waste liquid to be treated is pre-separated in the first rectifying tower 2, and qualified water d with the dioxane content of less than 50ppm is extracted from a tower kettle at 2000 kg/h; the top preconcentrate b was fed at 1111.8kg/h (where dioxane accounted for 54.2% (wt)) into a pressure pump feed mixer 1 and mixed with recycle i at a flow rate of 650.4kg/h, where dioxane accounted for 92.7% (wt) and water accounted for 7.3% (wt), and feed stream c after mixing in the feed mixer was pressurized and fed to a feed preheater preheated to 127 ℃, fed into a membrane distiller 6, pushed by the partial pressure difference of water vapor on both sides of the membrane module 7, with a large amount of water vapor entering the other side of the membrane module and withdrawn from a steam outlet 11 at a flow rate of 612.2 kg/h, where the dioxane content was about 16.7% (wt); a concentrated aqueous dioxane solution having a dioxane content of about 95.9 wt% was withdrawn through a concentrated liquid outlet 12 at a flow rate of 1150.1 kg/h; and (3) feeding the concentrated dioxane aqueous solution g into a second rectifying tower 14 for rectification, condensing and collecting 1300.2kg/h of steam h at the tower top of the second rectifying tower 14, wherein 650.1kg/h is taken as a circulating material i, feeding 650.1kg/h of steam into a second rectifying tower condenser 15 for condensation and reflux to the second rectifying tower 14, and collecting a high-purity dioxane product j with the purity of 99.95% (wt) from the tower bottom at the flow rate of 500 kg/h.
As noted above, while the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limited thereto. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (6)
1. A method for purifying high-grade dioxane from dioxane aqueous solution by using a device,
the device comprises a membrane distiller, two groups of rectifying towers, a pressure pump feed mixer, a pressure pump, a feed preheater and a steam condenser;
the membrane distiller comprises a membrane distiller cylinder, a membrane component, an orifice plate and an upper end enclosure; the membrane distiller comprises a membrane distiller cylinder and is characterized in that a membrane assembly is arranged inside the membrane distiller cylinder, the tops of the membrane assembly are connected through a plurality of through holes arranged on a pore plate, an upper end enclosure is mounted at the top of the membrane distiller cylinder, a steam discharge port is formed in the side surface of the upper end enclosure, and the bottom of the membrane distiller cylinder is sealed and is respectively provided with a gas-liquid mixing feed port and a concentrated liquid outlet; the two groups of rectifying towers comprise a first rectifying tower and a second rectifying tower, the first rectifying tower is provided with a feed liquid feed inlet to be treated and a reflux material feed inlet, the bottom of the first rectifying tower is provided with a first rectifying tower reboiler, the top of the first rectifying tower is provided with a steam discharge port and a tower kettle material discharge port, the second rectifying tower is provided with a concentrated dioxane aqueous solution feed inlet and a reflux material feed inlet, the bottom of the second rectifying tower is provided with a second rectifying tower reboiler, and the top of the second rectifying tower is provided with a steam discharge port and a tower kettle material discharge port;
the steam discharge hole of the first rectifying tower is connected with the feed inlet of a pressure pump feed mixer, the discharge hole of the pressure pump feed mixer is sequentially connected with a pressure pump and a feed preheater, the discharge hole of the feed preheater is connected with the gas-liquid mixing feed inlet of a membrane distiller, the steam discharge hole of the membrane distiller is connected with the feed inlet of a steam condenser, the discharge hole of the steam condenser is connected with the reflux material feed inlet of the first rectifying tower, the tower kettle material discharge hole of the first rectifying tower is connected with a reboiler of the first rectifying tower, the concentrated solution liquid outlet of the membrane distiller is connected with the concentrated dioxane aqueous solution feed inlet of the second rectifying tower, the reflux material feed inlet of the second rectifying tower is connected with the discharge hole of a condenser of the second rectifying tower, and the steam discharge hole at the top of the tower is respectively connected with the circulating material feed inlet of the second rectifying tower condenser and the pressure pump feed mixer, a tower kettle material discharge port of the second rectifying tower is connected with a second rectifying tower reboiler;
the method is characterized in that: the method comprises the following steps:
1) introducing a dioxane aqueous solution to be treated into a first rectifying tower through a feed inlet of a feed liquid to be treated of the first rectifying tower, separating the dioxane aqueous solution to be treated through gas-liquid mass transfer in the first rectifying tower, extracting a preconcentrated dioxane-water material from a steam discharge port of the first rectifying tower, and extracting qualified water from a material discharge port of a tower kettle of the first rectifying tower through a reboiler of the first rectifying tower; wherein, the pre-concentrated dioxane-water material is extracted to a pressure pump feeding mixer to be mixed with the circulating material, then is extracted, is pressurized by a pressure pump and then is extracted to a feeding preheater, and enters a membrane distiller from a gas-liquid mixing feeding port of the membrane distiller after being preheated;
2) in a membrane distiller, the preconcentrated dioxane-water material is fully contacted with a membrane component, water molecules dissolved with a small amount of dioxane are preferentially adsorbed on the surface of the membrane component, permeate through the membrane under the pushing of the partial pressure difference of water vapor on two sides of the membrane component, are vaporized into water vapor on the permeation side of the membrane, and are extracted through a vapor outlet of the membrane distiller; the partially dehydrated concentrated solution is extracted from the feed side of the membrane module through a concentrated solution outlet; steam extracted from a steam outlet of the membrane distiller is cooled by a steam condenser and then returns to a reflux material inlet of the first rectifying tower to be used as reflux liquid of the first rectifying tower; the concentrated solution extracted from the concentrated solution outlet of the membrane distiller enters a second rectifying tower through a concentrated dioxane aqueous solution feed inlet of the second rectifying tower;
3) rectifying the concentrated solution extracted by the membrane distiller in a second rectifying tower, extracting steam close to azeotropy from a steam outlet at the top of the second rectifying tower, and extracting a high-purity dioxane product from a material outlet at the bottom of the second rectifying tower through a reboiler of the second rectifying tower;
4) the vapor which is extracted from the top of the second rectifying tower and is close to the azeotrope is controlled by a valve component, and part of the vapor is extracted to a feed mixer of a pressure pump and enters a system as a circulating material; the other part of the mixed gas is cooled by a second rectifying tower condenser and then flows back to the tower kettle of the second rectifying tower.
2. A process as claimed in claim 1, wherein the purification of dioxane of good quality is carried out in an aqueous dioxane solution, the process comprising: and the membrane module sides in the first rectifying tower, the second rectifying tower and the membrane distiller are all operated under normal pressure.
3. A process as claimed in claim 1, wherein the purification of dioxane of good quality is carried out in an aqueous dioxane solution, the process comprising: the outlet pressure of the booster pump is 0.2-1.0 MPa.
4. A process as claimed in claim 3, wherein the purification of dioxane of good quality is carried out in an aqueous dioxane solution, the process comprising: the outlet pressure of the booster pump is 0.3-0.5 MPa.
5. A process as claimed in claim 1, wherein the purification of dioxane of good quality is carried out in an aqueous dioxane solution, the process comprising: in the preconcentrate material at the top of the first rectifying tower, the mass fraction of the dioxane is 45-80%; and in the steam extracted from the top of the second rectifying tower, the mass fraction of the dioxane is 80-95%.
6. A process as claimed in claim 1, wherein the purification of dioxane of good quality is carried out in an aqueous dioxane solution, the process comprising: the retention rate of dioxane in the membrane module and orifice plate combination is 85% -92%.
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| CN114212941A (en) * | 2021-12-21 | 2022-03-22 | 江苏三吉利化工股份有限公司 | System and method for recovering MOE (metal oxide organic ether) in ethylene glycol monomethyl ether wastewater |
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| CN103570191A (en) * | 2013-10-28 | 2014-02-12 | 浙江大学 | Biochemical treatment device and method for wastewater generated in production of polyester resin |
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