46 results about "Azeotropic distillation" patented technology

The invention relates to a process for extracting alcohols from an initial mixture (1) comprising alcohols in aqueous phase, with:a distillative separation by an isopropanol-butanol distillation column (III) equipped at the top with a condenser (c3), intended for separating said mixture into a water-isopropanol azeotrope stream (6) at the top and into a water-butanol azeotrope stream (7) at the bottom,a distillative separation intended for separating the water-butanol azeotrope stream into water and butanol, by a hetero-azeotropic distillation system comprising at least one water-recovering water column (IV) and at least one butanol (9)-recovering butanol column (V) equipped with a reboiler (r5),such that a heat transfer is performed from the top water-isopropanol azeotrope stream (6) entering the condenser of the isopropanol-butanol distillation column (III), to the stream entering the reboiler of the butanol column (V).

The invention discloses a knitted elastic composite sports suit and a preparation process thereof, and relates to the field of high polymer material modification and functional textiles, and the process comprises the following steps: firstly, thoroughly removing latent water in hollow silicon dioxide microspheres by using an azeotropic distillation technology, and regulating and controlling the density of active sites on the surfaces of the microspheres in cooperation with a double-effect silane system; then, grafting the modified microspheres to a polyurethane prepolymer main chain in situ under a low-temperature condition, and constructing an organic-inorganic covalent bonding network through a chain extension reaction; finally, modified fibers are prepared through dry spinning, and plaiting weave and moisture absorption and sweat releasing yarn are adopted for composite weaving. The technical problem that inorganic hollow filler is prone to gelation and spinning end breakage in polymerization is effectively solved, firm anchoring of functional particles in fibers is achieved, and the dynamic heat insulation stability, washing resistance and damp and hot comfort of sports suits are remarkably improved.

The invention relates to the technical field of organic synthesis, and discloses a synthesis process of salicylaldehyde. The process sequentially comprises three core stages: firstly, performing mechanochemical ball milling pretreatment on phenol, a catalytic complexing agent and a molecular sieve drying agent in an inert atmosphere; then, transferring the pretreated mixture into a reactor containing a composite solvent of sulfolane and ionic liquid [BMIM] PF6, and dropwise adding a hexamethylenetetramine solution under programmed temperature control to perform formylation reaction; and finally, cooling the reaction liquid, filtering, hydrolyzing the filtrate by using a phosphoric acid aqueous solution with gradient concentration, and separating the product in real time through azeotropic distillation. According to the process, mechanical activation, composite solvent and programmed reaction are combined, the process is continuous, and the reaction efficiency and selectivity are improved.

The invention discloses a method for recovering a tert-butyl acetate dealcoholization tower top material. Aiming at the problem that tertiary butanol and diisobutylene in a dealcoholization tower top material are unbalanced in proportion and cannot be directly recycled, the method comprises the following steps: adding a specific entrainer (such as methanol) into the material, and carrying out azeotropic distillation in a tertiary butanol recycling tower by utilizing the characteristic that the entrainer and diisobutylene form a lower-boiling-point azeotrope. An azeotrope of the entrainer and diisobutylene is extracted from the tower top, and an enriched tert-butyl alcohol material which can be directly recycled is obtained from the tower bottom. According to the method, only one rectifying tower unit is needed, the technological process is simple, the azeotrope which is difficult to treat through a traditional method is successfully separated, efficient recycling and cyclic utilization of the tert-butyl alcohol are achieved, it is not needed to purchase the tert-butyl alcohol to adjust the proportion, production raw material consumption and separation energy consumption of the tert-butyl acetate are remarkably reduced, and remarkable energy-saving and consumption-reducing benefits are achieved.

This invention discloses an azeotropic extraction apparatus and method for enhanced separation of a mixture of n-propanol, isopropanol, and acetonitrile using ionic liquids. The apparatus includes an azeotropic distillation column, a product separation column, an extractive distillation column, and two-stage adiabatic flash tanks. Part of the isopropanol from the top of the product separation column is refluxed to the azeotropic distillation column as an azeotropic agent. The ionic liquid from the bottom of the extractive distillation column is recovered via a first-stage flash tank and a second-stage flash tank. The vapor from the top of the second-stage flash tank is compressed by a compressor and then recycled back to the first-stage flash tank, forming a heat self-coupling. The control scheme includes temperature control via sensitive plates at both ends of the product separation column and cascade control of the extractant / azeotropic agent ratio. This invention operates at atmospheric pressure, avoiding investment in high-pressure equipment; the recovered ionic liquid purity reaches 99.9% and can be recycled long-term; and it can stably produce a product with a purity ≥99.9% even within a feed composition fluctuation range of ±30%.

The invention discloses a dehydration method of a raw material 1, 5-pentanediamine in a PDI synthesis process by a phosgenation method, which is characterized by comprising the following steps: firstly, uniformly mixing the raw material 1, 5-pentanediamine and a solvent chlorobenzene according to a mass ratio of 1: 3; secondly, according to the azeotropic distillation principle, water in the mixed material is slowly enriched at the tower top through reduced pressure distillation and tower top total reflux operation modes; thirdly, passing through a tower top oil-water two-phase dynamic separator, and slowly and continuously extracting the enriched water phase (upper layer) from an overflow port at the upper end of the dynamic separator; and then continuously extracting the qualified mixed material dehydrated in the tower kettle from the tower kettle. According to the method, the moisture content of the mixture of the dehydrated raw material 1, 5-pentamethylene diamine and the solvent chlorobenzene is less than or equal to 50ppm, the dehydration efficiency is high, and the operation cost is low. The technical index requirements of a PDI synthesis process by a phosgenation method are completely met.

The invention provides a process for inhibiting dioxane and unsulfonated substances in AES production, which comprises the following steps: (1) adding a composite inhibitor into a fatty alcohol-polyoxyethylene ether raw material for pretreatment, the composite inhibitor being composed of citric acid and EDTA (Ethylene Diamine Tetraacetic Acid); (2) carrying out sulfonation reaction on the pretreated raw materials by adopting sulfur trioxide; (3) neutralizing a sulfonated product; (4) sequentially carrying out water washing-azeotropic distillation and nanofiltration membrane separation on the neutralized product; and (5) drying to obtain a high-purity AES product. Synchronous removal of unsulfonated substances is realized, and an unexpected synergistic effect is generated through a composite inhibitor in a specific proportion.

The invention relates to the technical field of chemical engineering, and particularly discloses an anhydrous organic peroxy acid production system and method.The anhydrous organic peroxy acid production system comprises a peroxidation reaction distiller, a first oil-water separator, an azeotropic distillation tower and a second oil-water separation and light component removal tower, and moisture is brought out of a reaction system through two times of azeotropy and two times of oil-water separation; and the solvent and the entrainer are respectively recovered through the azeotropic distillation tower and the light component removal tower, and the recovered materials can be recycled. According to the present invention, with the method, the hydrogen peroxide conversion rate and the organic peroxy acid selectivity are high, the prepared anhydrous organic peroxy acid has characteristics of excellent quality and water content of less than 0.01%, and the process has advantages of short reaction time, high raw material utilization rate, high heat energy utilization rate and good economy.

Provided is a production method by which the amount of a heating medium to be used in a process for producing water-absorbing resin particles can be reduced and the water-absorbing resin particles can be efficiently produced.　This method for producing water-absorbing resin particles comprises a polymerization step, a concentration step, and a drying step in this order. In the polymerization step, a reaction liquid comprising a polymer of a water-soluble, ethylenically unsaturated monomer, water, and a dispersion medium is produced by reversed-phase suspension polymerization. In the concentration step, water is removed by azeotropic distillation while the dispersion medium of the reaction liquid is being refluxed to the reaction liquid, thereby reducing the water content of the reaction liquid to produce a concentrate. In the drying step, the concentrate is dried while being exposed to air, thereby producing a dried object. The content of residual water in the concentrate to be dried in the drying step is 72 mass% or greater with respect to the total mass of the polymer contained in the concentrate.

This utility model relates to the field of PBT production and discloses an integrated device for a THF recovery system in the PBT production process. It includes an integrated distillation column, a cyclone separator, and a reboiler. The integrated distillation column has a feed inlet in the middle, and its interior has a vertically connected azeotropic distillation dehydration chamber and a de-heavy component chamber. The cyclone separator is installed inside the integrated distillation column, connected to the feed inlet, and located between the azeotropic distillation dehydration chamber and the de-heavy component chamber. The reboiler is connected to the de-heavy component chamber. The liquid phase separated by the cyclone separator flows to the de-heavy component chamber to remove heavy component impurities with boiling points higher than THF, while the gas phase flows to the azeotropic distillation dehydration chamber to separate water azeotropes from THF. This utility model integrates a dehydration column and a pre-distillation column into a single distillation column, reducing the space occupied by the dehydration column and increasing the utilization rate of the plant space. The dual separation steps of the cyclone separator and the distillation column improve the dehydration and de-heavy component effects, reducing energy consumption.

The invention provides a synthesis method of mercaptopropyltrimethoxysilane, which comprises the following steps: dissolving industrial sodium hydrosulfide in a composite solvent, separating water through azeotropic distillation, reacting the separated and dewatered industrial sodium hydrosulfide-composite solvent solution with chloropropyltrimethoxysilane to obtain a reaction product, and carrying out heat preservation on the reaction product; carrying out cooling, filter pressing, rectification and separation on the reaction product subjected to heat preservation to obtain mercaptopropyltrimethoxysilane; the composite solvent comprises a first type of solvent and a second type of solvent, the first type of solvent is a non-water-soluble solvent, and the second type of solvent is a water-soluble solvent. According to the method, after water in sodium hydrosulfide is removed through azeotropic distillation, chloropropyltrimethoxysilane is added for full reaction, so that reaction products are prevented from being reacted with water, and after the reaction is completed, high-purity mercaptopropyltrimethoxysilane is obtained through cooling, filter pressing and distillation separation.

The utility model discloses a system for separating n-butyl alcohol from water by using a rectification-membrane separation integrated process. The system comprises an azeotropic rectification tower, a reboiler, a NaA molecular sieve pervaporation membrane device, a reflux pump and an n-butyl alcohol extraction pump, a feeding pipeline is arranged in the middle of the azeotropic rectifying tower, a gas phase outlet pipe is arranged at the top of the azeotropic rectifying tower, and a discharging pipe is arranged at the bottom of the azeotropic rectifying tower; the NaA molecular sieve pervaporation membrane device is arranged at the tower top, azeotrope of n-butanol and water can be effectively separated, a traditional azeotropic distillation process and a novel molecular sieve membrane dehydration separation technology are combined, azeotropic limitation of the n-butanol-water mixture is effectively broken through, efficient recovery of the two substances is achieved, and the production cost is reduced. The system is energy-saving, environment-friendly, high in recovery rate, low in investment and suitable for industrial application and popularization.

The invention belongs to the technical field of chemical synthesis processes, and particularly relates to a continuous batching method for preparing polyphenylene sulfide, and the method comprises the specific steps of reactive monomer batching, azeotropic agent mixing, azeotropic distillation, azeotropic agent recovery and product delivery. The method has the advantages that the method is simple in process, high in production efficiency, stable in dehydration product quality and simple in process control, and a binary azeotropic system is formed by the aid of the method and a water phase, so that process energy consumption and NMP (N-methyl pyrrolidone) loss are reduced, batches have good uniformity, and continuous burdening is realized. The method has the advantages of simple procedures, high production efficiency, stable dehydration product quality and simplicity in process control.

The invention belongs to the technical field of chemical separation, and particularly relates to a device and a method for separating and purifying tetrahydrofuran and n-butyl alcohol from gamma-butyrolactone production industrial waste liquid. The device comprises a pre-separation tower, an n-butyl alcohol refining tower, a water treatment tower, a butanone removal tower, a tetrahydrofuran extraction tower and a solvent recovery tower, the quality purity of tetrahydrofuran separated by adopting the device can reach 99.95% or above, the recovery rate can reach 94.3% or above, the quality purity of n-butyl alcohol can reach 99.5% or above, and the recovery rate can reach 99% or above. According to the method, a separation method combining extractive distillation and heterogeneous azeotropic distillation is adopted, an ionic liquid 1-butyl-3-methylimidazole acetate is used as an extraction agent for extractive distillation separation of a tetrahydrofuran-water mixture, and a mixture of n-butanol and water is separated through heterogeneous azeotropic distillation without adding an entrainer. The process provided by the invention plays an important role in environmental protection and clean production, and can realize low-energy-consumption, clean and efficient separation of the azeotropic system.

The application provides a separation and purification system and process for energy coupling variable pressure refining of butylamine, which comprises atmospheric azeotropic distillation of butylamine raw material containing water to separate a first distillate and a first still residue; pressure azeotropic distillation of the first distillate to separate a second distillate and a first target product; refluxing of the second distillate and atmospheric azeotropic distillation with the first still residue and butylamine raw material containing water to separate a third distillate and a third still residue, wherein the third still residue comprises n-butylamine, di-n-butylamine and tri-n-butylamine; distillation of the third still residue to separate a second target product, a third target product and a fourth target product; and the reaction conditions are selected from at least one of the following: a reflux ratio of 1.6-3.0 and a temperature of 43-63 DEG C for the atmospheric azeotropic distillation; and a reflux amount of 535 kg / h-2470 kg / h for the second distillate. The system and process of the application can greatly reduce equipment and operation costs on the basis of obtaining high-purity n-butylamine, di-n-butylamine and tri-n-butylamine products.

The invention relates to the technical field of organic wastewater treatment and recovery, and discloses a high-concentration degradation-resistant salt-containing organic wastewater resource recycling treatment process which comprises the following steps: S1, separating a water-low carbon alcohol azeotrope through azeotropic distillation to obtain an organic matter-rich low carbon alcohol phase and an inorganic salt concentrated aqueous solution; s2, separating the azeotrope into high-quality recycled water and high-purity recycled low-carbon alcohol; s3, feeding the two-phase mixture into a separator, and separating the two-phase mixture into a high-concentration organic matter-low carbon alcohol mixed solution and a high-purity inorganic salt concentrated water solution; s4, recovering inorganic salt crystals; and S5, thoroughly oxidizing the organic matter-low carbon alcohol mixed solution, separating out high-temperature and high-pressure carbon dioxide gas, and returning the separated high-temperature and high-pressure carbon dioxide gas to S1 for recycling. According to the invention, efficient resource recovery of water, inorganic salts and organic matters is realized through a multi-stage coupling separation technology, the problem of salt blockage of a supercritical water oxidation technology is fundamentally solved, and a new green and environment-friendly wastewater treatment path for medium cyclic utilization is constructed.

The invention relates to the technical field of chemical industry, and discloses a steam stripping coupling azeotropic rectification method for crude cyclohexanone-oxime, which comprises the following steps: introducing crude cyclohexanone-oxime into a rectifying tower for azeotropic rectification to obtain a tower kettle produced material which has a water content of less than or equal to 300 mass ppm and does not contain ammonia; on the basis of the total mass of the crude cyclohexanone-oxime, the crude cyclohexanone-oxime contains 10 to 30 weight percent of cyclohexanone-oxime, 60 to 80 weight percent of cyclohexane, 0.4 to 0.8 weight percent of water and 0.03 to 0.06 weight percent of ammonia; the azeotropic distillation conditions meet the conditions that the tower top pressure P1 is 30-60 kPa, the tower kettle pressure P2 is 45-65 kPa, the tower top temperature T1 is 40-60 DEG C, the tower kettle temperature T2 is 60-90 DEG C, and the reflux ratio is (0.03-0.2): 1; t2-T1 is greater than or equal to 9 DEG C, and the cyclohexane evaporation ratio is greater than or equal to 16.5%. The method provided by the invention can deeply remove water and ammonia in the crude cyclohexanone-oxime without causing hydrolysis and thermosensitive deterioration of the cyclohexanone-oxime.

The application relates to the field of wastewater treatment processes, in particular to a nitrile-containing wastewater treatment process and application thereof. The nitrile-containing wastewater treatment process comprises the following steps: (1) azeotropic distillation of the nitrile-containing wastewater; (2) hydrolysis treatment of the nitrile-containing wastewater in a pressure kettle. The nitrile-containing wastewater treatment process provided in the application can solve the problems in the existing nitrile-containing wastewater treatment process, the cost is lower than that of the oxidation method and the electrolysis method, the problem that the biological method is not suitable for industrialization is avoided, the operation is simple, and the process has excellent market prospect.

The invention discloses a preparation method of dioxolame for a solid-state battery, and relates to the technical field of solid-state batteries, the preparation method of dioxolame comprises the following steps: S1, condensation cyclization reaction: taking ethylene glycol and a formaldehyde source as raw materials, and carrying out condensation cyclization reaction in a reactor under the action of a solid acid catalyst, a reaction solution containing dioxolame and water is generated; s2, preliminary dehydration of the reaction liquid: carrying out azeotropic distillation dehydration on the reaction liquid obtained in the step S1, and removing water until the mass percent is below 7%; s3, further dehydration through membrane permeation: carrying out membrane permeation dehydration on the material obtained in the step S2, and removing water until the mass percent is below 2% by adopting a hydrophilic molecular sieve membrane separator; a multistage combined dehydration process of azeotropic distillation-membrane permeation-azeotropic distillation is adopted, and a hydrophobized solid acid catalyst is combined, so that high efficiency and energy conservation of the reaction and dehydration process are realized, and the problem that energy consumption of single azeotropic distillation is sharply increased under low water concentration is avoided.

The invention relates to a resourceful treatment process for an alkylation byproduct low-boiling-point substance in a BHT production process. The process mainly comprises three steps of preheating depolymerization, multi-stage water washing and phase separation purification, wherein firstly, low-boiling-point substances are preheated and depolymerized at the temperature of 50-60 DEG C, and residual isobutene is recovered; then, through three times of countercurrent water washing, TBA is transferred to a water phase by utilizing the hydrophilicity of TBA, and DIB is retained in an oil phase; and finally, concentrating and purifying the water phase by adopting a stripping tower to obtain industrial grade TBA with the concentration of more than or equal to 98wt%, rectifying the oil phase by adopting normal pressure to obtain industrial grade DIB with the concentration of more than or equal to 95wt%, and carrying out incineration treatment on residual liquid. According to the method, thermal activation and water washing are combined, the TBA / DIB azeotropic separation problem is effectively solved, high-energy-consumption azeotropic distillation is replaced, the technological process is simple, the operation condition is mild, the equipment requirement is low, the amount of hazardous waste can be reduced by 90% or above, the recycled product meets the relevant national standard, the resource utilization rate is high, economical efficiency is good, and industrial application and popularization are easy.

The application discloses an energy-saving coupling system for acetonitrile-water azeotropic distillation and a coupling reboiler. The system comprises a high-pressure rectifying tower and a low-pressure rectifying tower stacked in an up-down mode, a coupling reboiler, an auxiliary reboiler and a steam re-compressor. The condensation heat at the top of the high-pressure rectifying tower is used to drive the reboiling of the low-pressure rectifying tower in the coupling reboiler; the steam at the top of the low-pressure rectifying tower is pressurized and heated by the steam re-compressor, and the condensation heat thereof is used to drive the reboiling of the high-pressure rectifying tower in the auxiliary reboiler, thus forming a double-closed-circuit energy cycle. The application further discloses a coupling reboiler which adopts a structure of central feeding, bidirectional flow separation and end-top gas collection, and can efficiently realize heat coupling and non-condensable gas separation. The application reduces the energy consumption of the distillation process, improves the separation efficiency of the rich acetonitrile stream, and has compact structure and reliable operation.

The invention relates to a device and a method for recovering n-propyl acetate through azeotropic distillation. According to the method, the waste liquid obtained through activated carbon adsorption and desorption in the printing industry is subjected to azeotropic distillation to remove light components by adding an entrainer, and the high-purity n-propyl acetate solvent is recovered through distillation recovery. Waste liquid and cyclohexane enter a first rectification device in a continuous feeding mode to be subjected to azeotropic rectification, an azeotropic phenomenon exists between cyclohexane and ethyl alcohol, n-propyl alcohol, isopropyl alcohol and ethyl acetate, and azeotropic light components containing ethyl alcohol, n-propyl alcohol, isopropyl alcohol and ethyl acetate are extracted from the top of the first rectification device; and condensing the azeotropic component by a first condenser, partially refluxing and extracting to obtain a heavy component mainly containing n-propyl acetate, rectifying in second rectification equipment, extracting an n-propyl acetate solvent from the tower top, condensing by a second condenser, partially refluxing and extracting to obtain the n-propyl acetate. Heavy components containing propylene glycol monomethyl ether and n-butyl acetate are obtained in the second reboiler, and a solution in the second reboiler can be subjected to secondary rectification.

The invention discloses a device for separating methyl acetate and methanol by azeotropic distillation, comprising: a rectifying tower for storing a mixed solution of methyl acetate and methanol; the reboiler is arranged at the bottom of the rectifying tower, is communicated with the rectifying tower and is used for heating a mixed solution of methyl acetate and methanol in the rectifying tower; the condensing tank is arranged at one end of the top of the rectifying tower, communicated with the rectifying tower and used for condensing steam into liquid; the water scraping mechanism is arranged in the condensation tank and used for scraping water drops in the condensation tank; the liquid guide mechanism is arranged at the bottom of the condensation tank, is communicated with the condensation tank and is used for conveying condensed liquid; the extraction tank is arranged at the bottom of the liquid guide mechanism, is communicated with the liquid guide mechanism and is used for further extracting and purifying the condensed liquid; through the design of the water scraping mechanism, a liquid film on the outer wall of the condensation pipe is scraped off, so that the heat exchange effect of the condensation pipe is guaranteed.

The utility model provides a kind of for recovering acetic acid double-effect azeotropic distillation device system, the device system includes one-effect rectification unit and two-effect rectification unit;The two-effect rectification unit includes two-effect rectification device and vacuumizing unit, and the bottom of two-effect rectification device is connected with second two-effect reboiler and first two-effect reboiler;The top outlet of two-effect rectification device is connected with two-effect gas phase product separation unit;The one-effect rectification unit includes one-effect rectification device, and the top outlet of one-effect rectification device is connected with one-effect gas phase product separation unit by first two-effect reboiler.The utility model reduces energy consumption and simplifies recovery process by simultaneously adding high concentration acetic acid, low concentration acetic acid and ester into rectification device for azeotropic distillation;Meanwhile, in order to further reduce energy consumption, it is designed into double-effect azeotropic distillation device, by steam of one-effect as heat source of two-effect, so as to realize the saving of energy.

The application discloses a method for removing calcium and fixing carbon in fly ash washing liquid. The method uses the extraction of insoluble organic amine on acid to improve the pH value of the washing liquid system, continuously absorbs CO2, and realizes the complete removal of calcium in the fly ash washing liquid. The amine in the organic phase is regenerated by alkali, and the small amount of mixed organic diluent in the washing liquid is separated by azeotropic distillation to realize the reuse. The calcium carbonate product prepared by the method has small particles and high purity, is a high-quality globular aragonite type calcium carbonate particle, and can be used as a good adsorbent and additive material and has wide application in many fields.

The application discloses a treatment method of waste liquid in electrochemical production of adiponitrile, which comprises the following steps: waste liquid and chloroform enter a chloroform azeotropic distillation tower, acrylonitrile, water and chloroform obtained from the top of the tower enter a chloroform recovery tower, high-purity chloroform and waste water are obtained by phase separation from the top of the tower, and acrylonitrile and chloroform are obtained from the bottom of the tower; chloroform recovery tower bottom liquid enters an acrylonitrile tower, chloroform and a small amount of light components are removed from the top of the tower, and acrylonitrile is obtained from the bottom of the tower; chloroform azeotropic distillation tower bottom liquid enters an adiponitrile light component removal tower, acrylonitrile, propionitrile, water and a small amount of adiponitrile are obtained from the top of the tower, and adiponitrile and heavy components are obtained from the bottom of the tower; adiponitrile light component removal tower top liquid enters a by-product propionitrile recovery tower, propionitrile is recovered from the top of the tower, and propylamine is produced under the action of a hydrogenation catalyst and an additive; tower bottom liquid enters an adiponitrile tower, high-purity adiponitrile is obtained from the top of the tower, and the total recovery rate of adiponitrile is high; and tower bottom liquid enters a hexanetristitane tower, hexanetristitane is obtained from the top of the tower. The method realizes effective recovery of waste liquid and reduces the production cost of adiponitrile.

The invention relates to the technical field of chemical separation, and discloses an azeotropic rectification device for acetonitrile, dichloromethane and water, which comprises an evaporation kettle, a rectification tower, a tower top condenser, a reflux controller, a phase splitting tank, a refilling tank, a near infrared spectrum detector and a controller assembly. According to the present invention, the existing intermittent tower equipment does not need to be replaced, the dichloromethane purity can achieve the high level, the dichloromethane can be directly supplemented to the rectifying tower to continue to be used as the entrainer, the design of the secondary purification and the automatic switching of the supplementing branch is not needed, the new entrainer can be supplemented when necessary, and the efficient azeotropic process is ensured. The invention further discloses a control method of the device for azeotropic distillation of acetonitrile, dichloromethane and water.

The invention discloses a method for purifying halogenated alkane, and belongs to the technical field of environment-friendly refrigerants. In order to solve the problem that HCFC-244bb and HCFO-1233xf have close boiling points and are difficult to separate, an azeotropic distillation technology is innovatively adopted in the method. A crude product containing the two components is added into a rectifying tower, an azeotrope mainly containing HCFO-1233xf is extracted from the tower top by controlling conditions such as operation pressure, temperature and reflux ratio, and meanwhile, an HCFC-244bb product with the purity higher than 99.5% is obtained from a tower kettle. The key improvement is that the azeotrope at the tower top is returned to a reactor for producing HCFC-244bb for cyclic utilization. The method does not need to introduce an external extraction agent, is simple in process flow, effectively reduces the cost and the energy consumption, improves the utilization rate of raw materials, and is particularly suitable for precursor purification for synthesizing an environment-friendly refrigerant HFO-1234yf.

The invention relates to the technical field of lithium sulfide preparation, and provides a liquid-phase synthesis method of high-purity lithium sulfide, which comprises the following steps: S1, providing a reaction system containing an inorganic lithium salt and an organic solvent, the organic solvent containing an entrainer capable of forming an azeotrope with water; s2, in a protective atmosphere isolated from water and oxygen, heating the reaction system to a preset reaction temperature; s3, hydrogen sulfide gas is introduced into the heated reaction system for a reaction, azeotropic distillation is carried out at the same time, and water generated in the reaction and the entrainer are continuously moved out of the reaction zone in the form of azeotrope; and S4, after the reaction is finished, carrying out solid-liquid separation, washing and drying on a reaction product to obtain lithium sulfide. By adopting the organic solvent system containing the entrainer, the water generated by the reaction can be continuously and efficiently removed out of the reaction system. On one hand, reaction balance is broken, the reaction of hydrogen sulfide and lithium salt is promoted to be carried out in the direction of generating lithium sulfide, and the reaction efficiency and the conversion rate are improved.

This invention discloses a condenser, a method and system for recovering polyacrylonitrile waste liquid, and its application. The condenser of this invention has a longitudinally arranged H-shaped structure at its bottom. i Block baffle, the H i ≥1; and when the H i When ≥2, the H i The baffles, arranged in a stepped manner within the condenser, have varying heights. This invention optimizes the existing condenser structure. The condenser of this invention features multiple longitudinal baffles, each with a progressively decreasing height, forming a stepped distribution. This structural design allows for multiple separations of light acrylonitrile components and heavy components such as water within the condenser, effectively improving the separation and recovery of acrylonitrile. Furthermore, this invention provides a system for recovering polyacrylonitrile waste liquid. In addition to the specially designed condenser, it employs a positive pressure condensation process for the material collected from the top of the distillation column. This solves the problem of excessively low temperatures during negative pressure condensation in previous processes, which caused material overcooling and blockage of the condenser pipes. This also improves the separation and reflux effect of the material collected from the top of the azeotropic distillation column, thereby enhancing the overall separation and recovery efficiency of polyacrylonitrile waste liquid.