CN115536194A - Recovery treatment method for wastewater generated in production of epoxypropane by co-oxidation method - Google Patents
Recovery treatment method for wastewater generated in production of epoxypropane by co-oxidation method Download PDFInfo
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- CN115536194A CN115536194A CN202211065496.1A CN202211065496A CN115536194A CN 115536194 A CN115536194 A CN 115536194A CN 202211065496 A CN202211065496 A CN 202211065496A CN 115536194 A CN115536194 A CN 115536194A
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- evaporation
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- propylene oxide
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- 238000000034 method Methods 0.000 title claims abstract description 98
- 239000002351 wastewater Substances 0.000 title claims abstract description 52
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 32
- 238000011084 recovery Methods 0.000 title claims abstract description 21
- 238000011282 treatment Methods 0.000 title claims description 13
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims abstract description 123
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 97
- 238000001704 evaporation Methods 0.000 claims abstract description 85
- 230000008020 evaporation Effects 0.000 claims abstract description 72
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 47
- 239000011684 sodium molybdate Substances 0.000 claims abstract description 43
- 235000015393 sodium molybdate Nutrition 0.000 claims abstract description 43
- TVXXNOYZHKPKGW-UHFFFAOYSA-N sodium molybdate (anhydrous) Chemical compound [Na+].[Na+].[O-][Mo]([O-])(=O)=O TVXXNOYZHKPKGW-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000000926 separation method Methods 0.000 claims abstract description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
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- 239000000126 substance Substances 0.000 claims abstract description 29
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 20
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- 239000000243 solution Substances 0.000 claims description 41
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- 239000012071 phase Substances 0.000 description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
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- 230000008569 process Effects 0.000 description 4
- 159000000000 sodium salts Chemical class 0.000 description 4
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- RWGFKTVRMDUZSP-UHFFFAOYSA-N cumene Chemical compound CC(C)C1=CC=CC=C1 RWGFKTVRMDUZSP-UHFFFAOYSA-N 0.000 description 2
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- 239000000446 fuel Substances 0.000 description 2
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- 239000010842 industrial wastewater Substances 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- YPFDHNVEDLHUCE-UHFFFAOYSA-N propane-1,3-diol Chemical compound OCCCO YPFDHNVEDLHUCE-UHFFFAOYSA-N 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 241000183024 Populus tremula Species 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000011609 ammonium molybdate Substances 0.000 description 1
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 1
- 235000018660 ammonium molybdate Nutrition 0.000 description 1
- 229940010552 ammonium molybdate Drugs 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
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- 239000010440 gypsum Substances 0.000 description 1
- 230000000887 hydrating effect Effects 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
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- 238000002347 injection Methods 0.000 description 1
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- 239000001282 iso-butane Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Inorganic materials O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
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- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
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- VLAPMBHFAWRUQP-UHFFFAOYSA-L molybdic acid Chemical compound O[Mo](O)(=O)=O VLAPMBHFAWRUQP-UHFFFAOYSA-L 0.000 description 1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D7/00—Carbonates of sodium, potassium or alkali metals in general
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G39/00—Compounds of molybdenum
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
Abstract
The invention discloses a method for recovering and treating wastewater generated in the production of propylene oxide by an oxidation method, which comprises the steps of carrying out solid-liquid separation and multi-effect evaporation; evaporating and crystallizing the evaporated concentrated solution; separating and rectifying the evaporated vapor phase to obtain a propylene glycol product; evaporating and crystallizing the evaporated liquid phase, and then performing centrifugal separation; the centrifugally separated concentrated solution containing the crystal particles is sent to a sewage incinerator for incineration; the burned flue gas is discharged after waste heat recovery, dust removal, desulfurization and denitrification; after the solid ash rich in sodium molybdate and sodium carbonate is collected and conveyed by a collecting and conveying device, water is dissolved, solid insoluble substances are removed, and evaporation concentration is carried out after heat exchange is carried out on the water solution; removing sodium carbonate by crystallization separation; refining to obtain a sodium molybdate product; the method is suitable for treating the waste water which is rich in organic matters and inorganic matters and is generated in the production of the propylene oxide by the co-oxidation method, and can reduce the waste water treatment cost, increase the byproduct income and reduce the generation amount of hazardous wastes.
Description
Technical Field
The invention relates to the technical field of petrochemical industry, in particular to a method for recycling industrial wastewater, especially wastewater generated in the production of propylene oxide by a co-oxidation method.
Background
At present, a plurality of industrial production devices are already provided for producing the propylene oxide by the co-oxidation method, and the typical technical route is as follows: propylene oxide/styrene co-oxidation, propylene oxide/t-butanol co-oxidation, and propylene oxide/cumene peroxide co-oxidation.
Propylene oxide, also known as propylene oxide, is the third largest class of propylene derivatives after polypropylene and acrylonitrile. The propylene oxide is colorless ether-flavored liquid with a boiling point of 34 ℃. A large amount of alkaline wastewater is generated in the production process of the propylene oxide, and the alkaline wastewater has complex components, high alkalinity and high chemical oxygen consumption.
For the wastewater generated by the production of the propylene oxide by the co-oxidation method, the deep well injection landfill method is adopted for treatment in the early foreign country, the current treatment method is direct high-temperature incineration in Zhangxiong' high COD alkaline industrial wastewater treatment for the production of the propylene oxide in 2019, and the treatment cost per ton is as high as 500-600 yuan on the premise of not considering labor, maintenance and financial cost. And discusses the feasibility of biochemical treatment.
In the invention patent of propylene oxide production wastewater treatment method and multi-effect evaporation device thereof in 2005, liudebei in China mentions a method for producing calcium chloride crystals by carrying out multi-effect evaporation and concentration on wastewater. However, the scheme does not describe the composition of the multi-effect evaporation clear liquid, whether the calcium chloride contains dangerous waste or not, and a subsequent treatment method of the clear liquid and the calcium chloride.
Propylene glycol is an important chemical raw material, and 1, 2-propylene glycol can be prepared by hydrating propylene oxide. LuoJian proposes an improved method for separating a propylene glycol aqueous solution in '1, 3-propylene glycol four-tower rectification purification process optimization' in 2018, and the removal of water firstly can obviously reduce the energy consumption of rectification. According to the scheme, aspen is adopted to simulate four-tower rectification, and detailed engineering design parameters are not provided, so that the energy-saving effect needs to be further verified. The scheme flow is only suitable for the propylene glycol aqueous solution, and when the solution contains other components, a separation flow needs to be designed specifically.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for recovering and treating wastewater generated by producing propylene oxide by a co-oxidation method, which can recover organic matter propylene glycol, inorganic matter sodium carbonate and sodium molybdate. And can obviously reduce the waste water treatment cost, increase the byproduct income and reduce the generation amount of hazardous waste.
The purpose of the invention is realized by the following technical scheme:
a method for recycling wastewater generated in the production of propylene oxide by a co-oxidation method. The method comprises the following steps:
(1) Carrying out solid-liquid separation on the wastewater to remove solid insoluble substances possibly existing;
(2) Carrying out multi-effect evaporation concentration on the wastewater generated in the step 1 to obtain a concentrated solution;
(3) Evaporating and crystallizing the waste water concentrated solution, crystallizing and separating supersaturated solution obtained by evaporating and crystallizing, and selectively recycling clear liquid to an evaporation crystallization part or not to return the evaporation crystallization part;
(4) Performing propylene glycol rectification on the evaporation gas generated in the step 3 to remove light components and water, discharging the water out or sending the water into an epoxy propane production device for recycling, sending heavy components to an incineration or other treatment unit, and generating a propylene glycol product at the tower top;
(5) Carrying out high-temperature incineration on crystal slurry generated by crystallization and separation in the step 3, and discharging the incinerated flue gas after waste heat recovery, dust removal, desulfurization and denitrification;
(6) Collecting solid ash rich in sodium molybdate and sodium carbonate generated by high-temperature incineration in the step 5, and dissolving the solid ash in water to remove solid insoluble substances after passing through a conveying device;
(7) And (4) carrying out evaporation concentration on the aqueous solution obtained in the step (6), and carrying out evaporation crystallization on the concentrated solution to obtain sodium carbonate and sodium molybdate products.
Further, in step 1, the solid insoluble matter is removed by centrifugal separation, filtration, sedimentation, chemical flocculation or adsorption.
In the step 2, 2-effect to 5-effect evaporation is adopted, a multistage vacuum pump and an ejector are adopted to reduce the evaporation pressure or increase the evaporation pressure, the evaporation pressure is carried out at 8-101kPaA, and the molybdenum salt crystal slurry is removed from the inter-effect concentrated solution by adopting a settling method, a filtering method and a centrifugal separation method.
In the step 3, 8-101kPaA is adopted for reduced pressure evaporation crystallization, the supersaturated solution is centrifugally separated, and the separated clear liquid returns to a reduced pressure evaporation crystallizer; or a physical crystallization method of cooling crystallization, vacuum adiabatic cooling crystallization or salting-out crystallization is adopted, a physical separation method of filtering separation or settling separation is adopted, and a scheme that the clear liquid after separation does not return to the evaporative crystallizer is adopted.
In the step 4, the evaporation gas generated in the step 3 is rectified by propylene glycol, firstly rectified and dehydrated, then rectified to remove light components and rectified to remove heavy components, a propylene glycol product is produced at the tower top, and the tower pressure is set to be 8-101Kpa; or another propylene glycol rectification flow is adopted: removing heavy components, then dehydrating and rectifying to obtain the propylene glycol product.
In the step 5, the crystal slurry generated in the step 3 is subjected to high-temperature incineration, the furnace is of a top-burning vertical cylindrical furnace type, the temperature is more than 1100 ℃, the retention time is more than 2s, the heat of the incinerated high-temperature flue gas is recovered by a waste heat boiler, a high-temperature heat exchanger or a heat exchanger with a steam drum, the temperature of the high-temperature flue gas is 150-1100 ℃, the steam generated by the waste heat boiler is 0.1-10MPa, the middle-temperature flue gas after the heat is recovered is subjected to cloth bag dust removal, hydraulic dust removal or electrostatic dust removal, and then SCR denitration reaction is carried out, and the tail gas meeting the emission standard is discharged into the atmosphere; or, the square top-burning furnace type is adopted, the burning temperature and the residence time can be improved, the heat energy recovery can be arranged in any middle section, the SCR reaction temperature can be adjusted or the SCR is not arranged, and a desulfurization facility or a nitrogen oxide reduction facility can be selectively arranged.
And 6, collecting solid ash at the bottom of the incinerator, the bottom of the waste heat recovery boiler and a dust remover, collecting the solid ash at the bottom of the incinerator and the bottom of the waste heat recovery boiler by adopting a gravity dust collector, arranging pulse ash removal, mechanical ash removal, back-blowing ash removal, sound wave ash removal or shock wave ash removal in the dust remover to collect the solid ash, conveying the collected ash into a dissolving tank with a mechanical stirrer through a buried scraper conveyor, a bucket elevator, a trough conveyor or a belt conveyor, dissolving the solid ash by using desalted water, maintaining the temperature and the pressure in the dissolving tank, and removing insoluble substances by adopting a filtering method, a settling method, a chemical flocculation method or an adsorption method.
And 7, performing multiple-effect evaporation concentration on the aqueous solution containing sodium carbonate and sodium molybdate, returning the evaporated clear liquid to a dissolving tank, dividing the concentrated liquid into 3 strands of discharged materials, respectively removing sodium carbonate crystals and sodium molybdate crystals and returning the discharged materials to a multiple-effect evaporation inlet, setting the multiple-effect evaporation pressure to be 8-101KPA, respectively cooling and crystallizing the sodium carbonate and the sodium molybdate, returning the crystallized clear liquid to the multiple-effect evaporation inlet, respectively feeding the crystal slurry into a sodium carbonate and sodium molybdate product pushing centrifuge to obtain sodium carbonate and sodium molybdate products, and returning the clear liquid of the pushing centrifuge to the multiple-effect evaporation inlet.
After the step 6 and before the step 7, the aqueous solution containing sodium carbonate and sodium molybdate is subjected to product separation by adopting an ion exchange method and a solvent extraction method, and then the aqueous solution is subjected to the treatment of the step 7.
In step 7, the evaporation temperature and the solution concentration are adjusted according to a ternary system phase diagram of sodium carbonate-sodium molybdate-water, and the separation process is adjusted according to the quality requirements and energy consumption requirements of sodium carbonate and sodium molybdate products.
The beneficial effects of the invention are: the reasonable process is arranged, the organic matter propylene glycol, the inorganic matter sodium carbonate and the sodium molybdate can be recycled, the wastewater treatment cost can be obviously reduced, the byproduct income is increased, and the generation amount of hazardous waste is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and for those skilled in the art, other drawings may be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of the present invention for recovering organic substances from wastewater treatment in example 2;
FIG. 2 is a flow chart of the method for recovering inorganic substances from wastewater treatment according to example 2 of the present invention;
wherein: 1-multiple-effect evaporation, 2-dehydration tower, 3-light component removal tower, 4-evaporative crystallization, 5-pusher centrifuge, 6-propylene glycol rectifying tower, 7-incinerator, 8-waste heat boiler, 9, bag type dust collector, 10-SCR reactor, 11-dissolving tank, 12-evaporative concentration and 13-buffer tank.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following. Any feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The various terms appearing in this application are used for the purpose of describing particular embodiments only and are not intended as limitations of the invention, with the singular being intended to include the plural unless the context clearly dictates otherwise.
When the terms "comprises" and/or "comprising" are used in this specification, these terms are intended to specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence and/or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The technical scheme comprises the processes of multiple-effect evaporation, reduced pressure rectification, centrifugal separation, high-temperature incineration, waste heat boiler heat extraction, dust removal, SCR, crystallization, dissolution and heat exchange, and comprises the following steps: carrying out solid-liquid separation on the wastewater generated by producing the epoxypropane by the co-oxidation method, wherein the organic matters contained in the wastewater mainly comprise organic acid salt, propylene glycol and the like, and the inorganic matters mainly comprise sodium hydroxide, sodium salt and molybdenum salt inorganic matters, and carrying out multi-effect evaporation on the separated liquid; the evaporated clear liquid is recycled; evaporating and crystallizing the evaporated concentrated solution; separating and rectifying the evaporated vapor phase rich in organic matters, including propylene glycol and other light components, to obtain a propylene glycol product; crystallizing, centrifuging and concentrating the liquid phase after evaporation, namely the supersaturated solution; centrifugally concentrating concentrated crystal particle-containing concentrated solution, namely crystal slurry, and sending the crystal slurry to a sewage incinerator for incineration; the burned flue gas is discharged after waste heat recovery, dust removal, desulfurization and denitrification; after the solid ash rich in sodium molybdate and sodium carbonate is collected and conveyed by a collecting and conveying device, water is dissolved, solid insoluble matters are removed, and evaporation concentration is carried out after heat exchange is carried out on the aqueous solution; removing sodium carbonate by crystallization separation; refining the concentrated solution rich in sodium molybdate to obtain a sodium molybdate product; and refining the sodium carbonate to obtain a sodium carbonate product. The method is suitable for treating the waste water which is rich in organic matters and inorganic matters and is generated in the production of the propylene oxide by the co-oxidation method, and can reduce the waste water treatment cost, increase the byproduct income and reduce the generation amount of hazardous wastes.
The co-oxidation process for producing propylene oxide comprises: isobutane, ethylbenzene, cumene; the production wastewater comprises the following components: water, organic substances including propylene glycol, phenols and the like, sodium salt, molybdenum salt, sodium hydroxide, sodium carbonate and the like. The production wastewater can also be wastewater taking wastewater generated in the production of the propylene oxide by a co-oxidation method as a main component, namely wastewater generated in other links of a factory can be contained in the wastewater.
The recovery processing method comprises the following steps:
(1) Carrying out solid-liquid separation on the wastewater to remove solid insoluble substances possibly existing;
(2) Carrying out multi-effect evaporation concentration on the wastewater generated in the step 1 to obtain a concentrated solution;
(3) Evaporating and crystallizing the waste water concentrated solution, crystallizing and separating supersaturated solution, wherein clear liquid is rich in light organic matters such as propylene glycol and water, and the clear liquid can be selectively recycled to an evaporation crystallization part;
(4) Performing propylene glycol rectification on the evaporation gas generated in the step 3 to remove light component water, wherein the water can be discharged or sent to an epoxy propane production device for reuse, and the heavy component is sent to an incineration or other treatment unit; producing a propylene glycol product at the tower top;
(5) Carrying out high-temperature incineration on the crystal slurry generated in the step (3), incinerating the heavy components generated in the step (4) together with the crystal slurry, and carrying out waste heat recovery, dust removal, desulfurization and denitrification on the incinerated flue gas and then discharging;
(6) Collecting solid ash rich in sodium molybdate and sodium carbonate generated by high-temperature incineration in the step 5, and dissolving the solid ash in water to remove solid insoluble substances after passing through a conveying device;
(7) Evaporating and concentrating the aqueous solution obtained in the step 6, and evaporating and crystallizing the concentrated solution to obtain sodium carbonate and sodium molybdate products;
furthermore, the wastewater generated in the production of the propylene oxide by the co-oxidation method is often treated together with wastewater of other devices, and may contain or react to generate solid insoluble substances, and the solid insoluble substances are removed by means of a centrifugal separation method, a filtration method, a sedimentation method, a chemical flocculation method, an adsorption method and the like.
In the step (2), 2-5-effect evaporation is adopted, the evaporation pressure is 8-101KpaA, and the molybdenum salt crystal slurry is removed by setting a sedimentation measure for the inter-effect concentrated solution; the evaporation pressure can be reduced or increased by adopting a multi-stage vacuum pump and an ejector, and the inter-effect crystal slurry can be removed by adopting a filtering method and a centrifugal separation method;
in step (3): 8-101KPA is adopted for reduced pressure evaporation crystallization, the supersaturated solution is centrifugally separated, and the separated clear liquid returns to the reduced pressure evaporation crystallizer, or the following steps can be selected: a physical crystallization method of cooling crystallization, vacuum adiabatic cooling crystallization and salting-out crystallization is adopted, a physical separation method of filtering separation and settling separation is adopted, and a scheme that clear liquid after separation does not return to an evaporative crystallizer is adopted;
in step (4): the method comprises the following steps of (1) performing propylene glycol rectification on the evaporation gas containing water, propylene glycol and other small amount of impurities, performing rectification dehydration firstly, then performing rectification to remove light components, and performing rectification to remove heavy components, so as to obtain a propylene glycol product at the tower top, wherein the tower pressure is 8-101KPA, or the traditional propylene glycol rectification process can be adopted: removing heavy components, then dehydrating and rectifying to obtain a propylene glycol product, wherein water removed by rectification can be discharged, recycled, stripped, physically filtered and adsorbed to remove impurities, useless light components can be discharged into a torch and a fuel system, and the heavy components can be burned or used as fuel.
In step (5): and (2) carrying out high-temperature incineration on the crystal slurry, wherein the furnace is of a top-fired vertical cylinder furnace type, the temperature is more than 1100 ℃, the residence time is more than 2s, the high-temperature flue gas after incineration is subjected to heat recovery by using a waste heat boiler, the temperature of the high-temperature flue gas is 1100-150 ℃, the steam produced by the waste heat boiler is 0.1-10.0MPa, the medium-temperature flue gas after heat recovery is subjected to cloth bag dust removal, and then SCR denitration reaction at 250 ℃ is carried out, so that the tail gas which meets the emission standard is discharged into the atmosphere. Or other schemes are selected, square or other top-burning furnace types are adopted, the combustion temperature and the residence time can be improved, the waste heat boiler can be changed into a high-temperature heat exchanger and a heat exchanger with a steam pocket, heat energy recovery can be arranged in any middle section, bag type dust removal can be changed into other forms of filtering dust removal, such as hydraulic dust removal and electrostatic dust removal by a Venturi scrubber, SCR (Selective Catalytic Reduction) can be omitted or the reaction temperature of the SCR can be adjusted, and the principle is that the selectivity of N2 is improved under the Catalytic action, and the consumption of NH3 is reduced. The method can be used for selectively arranging desulfurization facilities or arranging other methods for reducing nitrogen oxides, the flue gas desulfurization and denitration technology is a boiler flue gas purification technology applied to the chemical industry for generating multiple nitrogen oxides and sulfur oxides, the nitrogen oxides and the sulfur oxides are one of main sources of air pollution, so the application of the technology has great benefits for purifying ambient air, and the known flue gas desulfurization and denitration technologies comprise the technologies such as the PAFP, the ACFP, the pyrolusite method, the electron beam ammonia method, the pulse corona method, the gypsum wet method, the catalytic oxidation method, the microbial degradation method and the like.
In step (6): incinerator bottom, exhaust-heat boiler bottom, the sack cleaner will collect solid ash content, and the composition volume ratio is roughly 2:5:3, the temperature is approximately 700 ℃, 350 ℃ and 250 ℃, the first two parts of dust are collected by adopting a gravity dust collector, the rear part is cleaned by a bag-type dust collector and pulse dust is arranged, the collected ash is conveyed into a dissolving tank with a mechanical stirrer through a buried scraper conveyor, sodium carbonate and sodium molybdate ash are dissolved by desalted water, the temperature in the dissolving tank is maintained at 120 ℃, the pressure is 200KPA, an inner coil is arranged for heating, a continuous settling tank is adopted for removing insoluble substances, or other schemes can be adopted: adjusting the position of a flue gas heat recovery section, changing the discharge temperature and the discharge proportion of solid ash, replacing pulse ash removal with mechanical ash removal, back-flushing ash removal, sound wave ash removal and shock wave ash removal, replacing a buried scraper conveyor with mechanical conveyors such as a scraper conveyor, a bucket elevator, a trough conveyor, a belt conveyor and the like, adjusting the temperature of a dissolving tank to be 0-400 ℃ and the pressure to be 0-29MPa, adjusting the heat removal of an inner coil, adopting an outer coil to remove heat, directly removing heat or a heat exchanger to remove heat, adopting a quenching furnace type to completely or partially give up heat removal, and adopting a filtration method, other sedimentation methods, a chemical flocculation method and an adsorption method to replace a continuous sedimentation tank;
in step (7): performing multiple-effect evaporation concentration on an aqueous solution containing sodium carbonate and sodium molybdate, returning an evaporation clear solution to a dissolving tank, dividing a concentrated solution into 3 strands of discharge materials, 1 strand of sodium carbonate crystal removal, 1 strand of sodium molybdate crystal removal, 1 strand of multiple-effect evaporation inlet return, multiple-effect increasing pressure of 8-101KPA, temperature of the multiple-effect evaporation concentrated solution of 80 ℃, cooling and crystallizing sodium carbonate and sodium molybdate respectively, returning a crystallization clear solution to the multiple-effect evaporation inlet, respectively allowing crystal mush to enter a sodium carbonate and sodium molybdate product pushing centrifuge, obtaining sodium carbonate and sodium molybdate products, returning a pusher clear solution to the multiple-effect evaporation inlet, or adopting other schemes: the method comprises the steps of separating products from an aqueous solution containing sodium carbonate and sodium molybdate by adopting an ion exchange method and a solvent extraction method, adjusting evaporation temperature and solution concentration according to a ternary system phase diagram of sodium carbonate-sodium molybdate-water, adjusting a separation process according to quality requirements and energy consumption requirements of sodium carbonate and sodium molybdate products, abandoning sodium carbonate products, changing the sodium carbonate products into solutions, directly discharging the solutions, further processing the sodium molybdate solution to prepare molybdic acid or ammonium molybdate, and increasing measures for separating trace impurities according to the types of metals and non-metals added in raw material wastewater;
example 1, comprising the steps of:
(1) And (4) carrying out solid-liquid separation on the wastewater to remove solid insoluble substances possibly existing. The wastewater in the scheme mainly contains organic matters: phenols 5309mg/kg, propylene glycol 33480mg/kg, styrene 109mg/kg, others 2910mg/kg; 350-630mg/L of inorganic molybdenum and 1.3-2.8wt% of sodium salt; the pH value is 12.5-13.2. The waste water is stored for a long time or is mixed with waste water of other devices, insoluble substances are easily generated, and solid-liquid separation equipment, preferably a cyclone separator, needs to be arranged. The separated bottom flow containing the solid is sent to a high-temperature incineration inlet.
(2) And carrying out multi-effect evaporation concentration on the primary treatment wastewater. The main purpose of the concentration is to reduce the water content entering the high temperature incineration. Methanol, propylene oxide, ethylene glycol, propylene glycol will evaporate into the gas phase together with water. 2-5 effect evaporation is most economical. Due to the concentration effect of each effect, a small amount of crystal mush is generated and can be separated and removed.
(3) And (4) evaporating and crystallizing the waste water concentrated solution. In order to further reduce the amount of water entering high-temperature incineration, the waste water is evaporated and crystallized, the gas phase of the evaporation crystallizer is mixed with the multi-effect evaporation gas phase, and the liquid phase enters a centrifugal machine for separation. And feeding the separated crystal mush into high-temperature incineration.
(4) And (4) rectifying the evaporated gas by using propylene glycol. The rectification adopts negative pressure operation, and can obviously reduce the energy consumption of rectification. Removing water and above light components. The height and the pressure of the light component removal tower are adjusted according to the actual content of methanol, propylene oxide, ethylene glycol and the like, and water can be discharged or recycled by a propylene oxide production device. Then removing heavy components below the propylene glycol. Propylene glycol can be withdrawn from the top or upper side of the rectification column. Preference is given to packing trays.
(5) And (4) carrying out high-temperature incineration on the crystal mush. According to the standard requirements of hazardous waste incineration pollution control standards, the incineration temperature of the incinerator is more than or equal to 1100 ℃, and the smoke retention time is more than or equal to 2S. In order to recover heat, a series of heat extraction is carried out on the burned flue gas, and the heat can be used for generating steam, heating cold water and other cold media. For maximum heat recovery, a bag house is provided to collect the solid ash particles. And a medium-temperature SCR denitration reactor is arranged to ensure that the indexes of the discharged tail gas are qualified.
(6) And collecting and dissolving the solid ash after incineration. And collecting solid ash generated by different cooling sections and dust removal sections through gravity. Referring to a bulk conveying method mentioned in Zhuyun metallurgical equipment, solid ash is delivered into a dissolving tank with a stirrer by the conveying equipment. The ash dissolves exothermically, so a heat extraction device is arranged to extract heat. A continuous settler was disposed after the dissolution tank to remove insoluble matter.
(7) And (3) evaporating and concentrating the aqueous solution, and evaporating and crystallizing the concentrated solution to obtain sodium carbonate and sodium molybdate products. And (3) obtaining supersaturated solution by adopting multi-effect evaporation and concentration, and then obtaining sodium carbonate and sodium molybdate products according to ternary phase diagrams of sodium carbonate, sodium molybdate and water at different temperatures. And the purity and the water content can be flexibly adjusted according to the product requirements. The evaporation and crystallization equipment of the equipment is selected according to Zhuyun metallurgy equipment.
Through the steps, the method can reduce the treatment cost of the wastewater generated in the production of the propylene oxide by the co-oxidation method to the maximum extent, and can create economic benefits.
Example 2: a method for treating waste water of a device for producing 28.5 ten thousand tons of propylene oxide and 62 ten thousand tons of styrene by a co-oxidation method and recovering organic matters and inorganic matters.
As shown in the detailed flow chart of FIG. 1, the wastewater from the production of propylene oxide by the co-oxidation method at a flow rate of 25t/h contains 5309mg/kg of phenols, 33480mg/kg of propylene glycol, 109mg/kg of styrene and 2910mg/kg of styrene; 350-630mg/L of inorganic molybdenum and 1.3-2.8wt% of sodium salt; the pH value is 12.5-13.2. After insoluble substances are separated by a cyclone separator, the insoluble substances enter a multi-effect evaporator. In the multiple effect evaporator 2 of fig. 1, about 70% of the water is vaporized into the gas phase using a 4-effect co-current evaporation scheme. About 10% of the water is evaporated in the reduced-pressure evaporative crystallizer 3. Methanol, propylene oxide, ethylene glycol, propylene glycol will evaporate into the gas phase together with water. The salt crystals formed in the evaporative crystallizer are separated by a pusher centrifuge. Discharging the crystal slurry into a high-temperature incinerator, and returning clear liquid to a crystallization evaporator. In order to prevent the crystal mush from crystallizing in the delivery pump, a steam half-pipe heat tracing is adopted for a pipeline from the pusher to the incinerator.
Gathering gas phases of the multi-effect evaporator and the evaporative crystallizer, and enabling the gas phases to enter a dehydration tower, wherein the operation pressure at the top of the tower is 15KPaA. The water containing light components such as methanol, glycol and the like enters a light component removal tower, the operation pressure at the top of the tower is 8KPaA, and the light components are discharged into an incinerator fuel gas system. The water at the bottom of the light component removal tower is filtered by active carbon and then sent to a device for producing the propylene oxide by a co-oxidation method for recycling. The material at the bottom of the dehydration tower enters a propylene glycol rectifying tower 6, and a propylene glycol product is obtained at the top of the tower. Heavy components at the bottom of the tower are pumped at the bottom of the tower and are converged into crystal slurry to enter an incinerator for incineration.
The crystal slurry is sent to the top of a furnace, and after 2S high-temperature incineration at 1150 ℃, organic matters are oxidized into carbon dioxide, water and nitrogen oxides. All inorganic salts exist in the form of solid ash after incineration, are captured and collected through the bottom corner of the incinerator, a waste heat boiler and a bag type dust collector, and are conveyed into a dissolving tank through an embedded scraper conveyor. In order to avoid generating dioxin, the temperatures of the incinerator bottom, the waste heat boiler outlet and the bag type dust collector are respectively controlled to be 700 ℃, 350 ℃ and 250 ℃. Through tests and simulation, the ash discharge ratio is predicted to be 2:5:3, the total ash content is 1.8t/h. And selecting a proper buried scraper conveyor according to the data to convey the ash into the dissolving tank. The incineration flue gas passes through a waste heat boiler, a bag type dust collector and an SCR reactor and then is discharged into a chimney.
In the dissolving tank 11, ash is dissolved. Adding an auxiliary agent to remove insoluble substances, then entering a double-effect evaporator for concentration, cooling a gas phase, and returning to the dissolving tank. The evaporation capacity of the evaporator does not need to be too large, and the sodium carbonate is supersaturated at the outlet under 80 ℃. The sodium carbonate in the buffer tank generates crystal growth, and then the sodium carbonate is pumped into a two-stage centrifugal pusher to separate out sodium carbonate products, wherein the estimated yield is 1.5t/h. And (4) leading out a material from the buffer tank, and producing a sodium molybdate product through the improved water-cooled crystallizer, wherein the yield of the sodium molybdate product is low, and is estimated to be 25kg/h. Therefore, the crystallization of the sodium molybdate product adopts discontinuous operation.
The above embodiment is a preferable scheme of applying the technical scheme of the invention to the wastewater treatment of the device for producing 28.5 ten thousand tons of propylene oxide and 62 ten thousand tons of styrene by using the co-oxidation method. The scheme can reduce the energy consumption of high-temperature incineration, and produce 1500kg/h of sodium carbonate, 500kg/h of propylene glycol and 25kg/h of sodium molybdate. Compared with the current direct cost of wastewater treatment of 38.78 yuan/ton, the method has obvious economic benefit.
In other technical features of the present embodiment, those skilled in the art can flexibly select the specific features according to actual situations to meet different specific actual requirements. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known components, structures or parts are not described in detail in order to avoid obscuring the present invention, and the technical scope of the present invention is defined by the claims. The phraseology of the present specification, including the drawings, should not be regarded as limiting in any way the claims.
Modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, which should be limited only by the appended claims. In the previous description, numerous specific details were set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known techniques, such as specific construction details, operating conditions, and other technical conditions, have not been described in detail in order to avoid obscuring the present invention.
Claims (10)
1. A method for recycling and treating wastewater generated in the production of propylene oxide by an oxidation method is characterized by comprising the following steps:
(1) Carrying out solid-liquid separation on the wastewater to remove solid insoluble substances possibly existing;
(2) Carrying out multi-effect evaporation concentration on the wastewater generated in the step 1 to obtain a concentrated solution;
(3) Evaporating and crystallizing the waste water concentrated solution, crystallizing and separating supersaturated solution obtained by evaporating and crystallizing, and optionally recycling clear liquid to an evaporation crystallization part or not returning to the evaporation crystallization part;
(4) Performing propylene glycol rectification on the evaporation gas generated in the step 3 to remove light components and water, discharging the water out or sending the water into an epoxy propane production device for recycling, sending heavy components to an incineration or other treatment unit, and generating a propylene glycol product at the tower top;
(5) Carrying out high-temperature incineration on crystal slurry generated by crystallization and separation in the step 3, and carrying out waste heat recovery on the incinerated flue gas,
Discharging after dedusting, desulfurization and denitrification;
(6) Collecting solid ash rich in sodium molybdate and sodium carbonate generated by high-temperature incineration in the step 5, and dissolving the solid ash in water to remove solid insoluble substances after passing through a conveying device;
(7) And (4) carrying out evaporation concentration on the aqueous solution obtained in the step (6), and carrying out evaporation crystallization on the concentrated solution to obtain sodium carbonate and sodium molybdate products.
2. The method for recovering and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in step 1, the solid insoluble substances are removed by a centrifugal separation method, a filtration method, a sedimentation method, a chemical flocculation method or an adsorption method.
3. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in the step 2, 2-effect to 5-effect evaporation is adopted, a multistage vacuum pump and an ejector are adopted to reduce the evaporation pressure or increase the evaporation pressure, the evaporation pressure is carried out at 8-101kPaA, and the molybdenum salt crystal slurry is removed from the inter-effect concentrated solution by adopting a settling method, a filtering method and a centrifugal separation method.
4. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in the step 3, 8-101kPaA is adopted for reduced pressure evaporation crystallization, the supersaturated solution is centrifugally separated, and the clear liquid after separation returns to the reduced pressure evaporation crystallizer; or a physical crystallization method of cooling crystallization, vacuum adiabatic cooling crystallization or salting-out crystallization is adopted, a physical separation method of filtering separation or settling separation is adopted, and a scheme that the clear liquid after separation does not return to the evaporative crystallizer is adopted.
5. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in the step 4, the evaporation gas generated in the step 3 is rectified by propylene glycol, firstly rectified and dehydrated, then rectified to remove light components and rectified to remove heavy components, a propylene glycol product is produced at the tower top, and the tower pressure is set to be 8-101Kpa; or another propylene glycol rectification flow path is adopted: removing heavy components, then dehydrating and rectifying to obtain the propylene glycol product.
6. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in the step 5, the crystal slurry generated in the step 3 is subjected to high-temperature incineration, the furnace is of a top-fired vertical cylindrical furnace type, the temperature is higher than 1100 ℃, the retention time is longer than 2s, the high-temperature flue gas after incineration is subjected to heat recovery by using a waste heat boiler, a high-temperature heat exchanger or a heat exchanger with a steam drum, the temperature of the high-temperature flue gas is 150-1100 ℃, the steam generated by the waste heat boiler is 0.1-10MPa, the medium-temperature flue gas after heat recovery is subjected to cloth bag dust removal, hydraulic dust removal or electrostatic dust removal, and then SCR denitration reaction is carried out, and the exhaust gas meeting the emission standard is discharged into the atmosphere; or, the square top-burning furnace type is adopted, the burning temperature and the residence time can be improved, heat energy recovery can be arranged in any middle section, the SCR reaction temperature can be adjusted or SCR is not arranged, and a desulfurization facility or a nitrogen oxide reduction facility can be selectively arranged.
7. The method for recovering and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: and 6, collecting solid ash at the bottom of the incinerator, the bottom of the waste heat recovery boiler and a dust remover, collecting the solid ash at the bottom of the incinerator and the bottom of the waste heat recovery boiler by adopting a gravity dust collector, arranging pulse ash removal, mechanical ash removal, back-blowing ash removal, sound wave ash removal or shock wave ash removal in the dust remover, collecting the solid ash, conveying the collected ash into a dissolving tank with a mechanical stirrer through an embedded scraper conveyor, a bucket elevator, a groove conveyor or a belt conveyor, dissolving the solid ash by desalted water, maintaining the temperature and the pressure in the dissolving tank, and removing insoluble substances by adopting a filtration method, a sedimentation method, a chemical flocculation method or an adsorption method.
8. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: and 7, performing multi-effect evaporation concentration on the aqueous solution containing sodium carbonate and sodium molybdate, returning the evaporated clear liquid to a dissolving tank, dividing the concentrated solution into 3 strands of discharged materials, respectively removing sodium carbonate crystals and sodium molybdate crystals and returning to a multi-effect evaporation inlet, setting the multi-effect evaporation pressure to be 8-101KPA, respectively cooling and crystallizing sodium carbonate and sodium molybdate, returning the crystallized clear liquid to the multi-effect evaporation inlet, respectively feeding the crystal slurry into a sodium carbonate and sodium molybdate product pusher centrifuge to obtain sodium carbonate and sodium molybdate products, and returning the clear liquid to the multi-effect evaporation inlet.
9. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: after the step 6 and before the step 7, performing product separation on the aqueous solution containing sodium carbonate and sodium molybdate by adopting an ion exchange method and a solvent extraction method, and then performing the treatment of the step 7 on the aqueous solution.
10. The method for recycling and treating the wastewater generated in the production of the propylene oxide by the co-oxidation method according to claim 1, which is characterized in that: in step 7, the evaporation temperature and the solution concentration are adjusted according to a ternary system phase diagram of sodium carbonate-sodium molybdate-water, and the separation process is adjusted according to the quality requirement and the energy consumption requirement of sodium carbonate and sodium molybdate products.
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| CN111559819A (en) * | 2020-04-30 | 2020-08-21 | 常州瑞华化工工程技术股份有限公司 | Method for recovering propylene glycol and other organic matters from propylene epoxidation alkaline washing wastewater |
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| CN115818671A (en) * | 2023-02-10 | 2023-03-21 | 焦峰 | Method for crystallizing and purifying sodium carbonate of incineration product |
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