Abstract: A method for operating a column having a region for reaction with distillation of fluid streams is provided with structures including catalyst-filled containers having liquid permeable upper surfaces which allow for the accumulation and flow of liquid from a liquid stream. The containers include catalyst beds positioned beneath the upper surface of the containers. A portion of the liquid on the containers is driven through the catalyst bed by the liquid head created by the accumulated liquid and is catalytically reacted. Another portion of the liquid may be directed through a downcomer which allows the accumulated liquid to leave the container without passing through the catalyst bed so that higher volumetric flow rates can be achieved.

Abstract: A column to regenerate methanol from a methanol-water mixture includes a circular column having two contact beds with a plurality of gas inlets connected thereto to split the entering feed gas so that approximately equal portions are fed through each bed. An inlet near the top of the column allows a methanol-water mixture to be introduced to flow down through the two contact beds, countercurrent to the feed gas.

Abstract: A process and apparatus for improving the thermal efficiency of a steam turbine power generating plant while simultaneously desalinating seawater or brine and purifying water which contains minerals, salts, and other dissolved solids. Exhaust gases from a power plant is heat exchanged against water in a secondary ecomomizer which circulates water at a temperature near, or slightly above the dewpoint of the combustion exhaust of the high-pressure boiler. The heated water is flashed to produce low-pressure steam. The low-pressure steam is condensed against the last effect of a multi-effect desalinization unit. Steam from the first effect of the desalination unit is condensed against steam condensate from the power plant turbine to preheat the condensate and thereby recover heat from the power plant's exhaust gas. Salinous water is fed to the multi-effect desalinization unit to produce fresh water and a concentrated brine.

Abstract: Inhibition performance is improved in styrene processing through the addition of a stable nitroxide free radical compound to the styrene feed and to the reflux of at least one column.

Abstract: A method of separating water from an aqueous emulsion using a minimum of energy includes heating the aqueous emulsion in a sump, conveying concentrated emulsion from the sump to a heat exchanger so as to pass therethrough back to the sump, circulating water vapor and non-condensable gases from the sump through a compressor to raise its temperature and passing the heated water vapor and non-condensable gases through the heat exchanger to condense and heat the concentrated emulsion therein and evaporate water therefrom, a thermostat filled with water and water vapor, together with first and second pressure switches respectively communicating with the sump and the external atmosphere and the heat exchanger and the external atmosphere, maintaining a temperature differential between 0.5.degree. and 3.degree. C. between the aqueous emulsion in the sump and the temperature of the compressed water vapor and noncondensable gases.

Abstract: Acetaldehyde may be effectively removed from a contaminated methanol stream using a distillation method wherein a solvent stream containing a relatively heavy polar compound such as water or propylene glycol is utilized as an extractive distillation solvent. Following the separation of the polar compound from the bottoms stream obtained by extractive distillation, the purified methanol may be recycled for use as a reaction solvent in an olefin epoxidation process.

Abstract: A process is provided for the isolation of (meth)acrylic acid from a mixture containing (meth)acrylic acid as the main component and lower aldehydes as secondary components by rectification in a rectification column having a stripping section and a rectification section, wherein the starting mixture containing the (meth)acrylic acid to be isolated by rectification is not fed directly to the rectification column but is first passed into a heated dwell vessel which is connected to the vapor side of the rectification section of the rectification column and in which the starting mixture is kept at the boil and, instead of the starting mixture as such, the bottom liquid of the dwell vessel is fed to the rectification column.

Abstract: A method for removing residual vinyl chloride monomers from an aqueous slurry is disclosed. The method preferably utilizes a tower having a plurality of vertically spaced plates, which define a plurality of chambers, each chamber defined between adjacent plates. The tower features a plate in one of the chambers having a diameter of 1.05 to 5 times larger than the diameter of the plates in chambers above and below the chamber having the large plate. The method is based upon introducing the slurry to a particular location in the tower depending upon the porosity of the polyvinyl chloride in the slurry.

Abstract: In the purification of an aqueous acetone-contaminated propylene oxide feedstock in an extractive distillation column in the presence of an oxyalkylene glycol extractive distillation agent under distillation conditions selected to promote the formation and maintenance of an acetone buffer in the distillation column, a higher boiling (heavier) distillation fraction containing substantially all of the oxyalkylene glycols, water, and acetone introduced into the extractive distillation column is continuously withdrawn and the higher boiling (heavier) distillation fraction is partially vaporized in a first reboiler; the remaining liquid being partially vaporized in a second reboiler and the vapors being recycled to the extractive distillation column.

Abstract: Processes are provided for producing a pure grade of acrylic acid having residual aldehyde levels under 10 parts per million. The processes apply selected groups of amines sequentially and, preferably, continuously in selectively reducing, for example, acrolein and furfural, and may be advantageously conducted in the presence of maleic acid and maleic anhydride impurities.

Abstract: A process and apparatus for the production of a beverage distills aqueous influent into a forerun overhead fraction that is the first result of a distillation operation, a distillate, and a bottom products fraction that is left over from the aqueous influent without being distilled. The forerun overhead fraction is removed, the distillate is sterilized and remineralized into the beverage, and the bottom products fraction is removed so the process can begin again with more aqueous influent.

Abstract: Impure 2,6-diisopropylphenol (DIP) is purified by use of a distillation process in which a single distillation column is used. The process comprises: (a) subjecting the impure DIP to a first continuous distillation in the column in an inert environment to distill off lower boiling components and produce first column bottoms enriched in DIP; (b) collecting, cooling and storing the first column bottoms while continuously maintaining them in an inert environment; (c) discontinuing the first continuous distillation; (d) subjecting the first column bottoms to a second continuous distillation in an inert environment in the same column to produce a second overhead distillate composed of purified DIP. The process avoids the formation in the distilling mixtures of dose boiling impurities due to seepage of air through standard pipe flanges and fittings and consequent oxidation reactions which occur under the conditions needed for batch distillations conducted in typical industrial distillation facilities.

Abstract: In a solvent recovery plant including a recovery or distillation tower from which solvent product is recovered overhead, an isothermal separator, preferably a cyclone, is used to separate liquid phase contaminant (i.e. oil in a lubricating oil extraction process) in overhead product and to feed the separated liquid to the recovery tower as reflux. In addition, a portion of the feed to the tower can be branched off and mixed with the overhead product to bring its temperature down to close to the dew point of the solvent vapor. In this way, flooding of the uppermost tower trays and distillation of oil overhead can be overcome.

Abstract: A process for separating a mixture containing mainly ethyl tertio-butyl ether (ETBE), ethanol and C.sub.4 hydrocarbons includes introducing the mixture to be separated into a debutanizer from which the C.sub.4 hydrocarbons are recovered overhead with a fraction of the ethanol, and purified ETBE is recovered as a bottom product; a side stream of an ethanol-rich phase is extracted and sent to a permeation zone in which the dense film of the membrane is constituted by a N,N-dimethylaminoethyl methacrylate polymer (DMAEMA) or a copolymer of DMAEMA with N-vinylcaprolactam (NVCL) and/or with N-vinyl pyrrolidone (NVP); the ethanol-depleted retentate from this permeation zone is returned to the debutanizer and the permeate contains mainly separated ethanol.The process can be integrated into an ETBE production process, in which the ethanol separated during the permeation step is recycled to the etherification reactor. The debutanizer may be replaced by a catalytic distillation column.

Abstract: An improved ocean thermal energy conversion (OTEC) system which includes a novel combined evaporator/condenser. The combined evaporator/condenser further includes a plurality of evaporator spouts and a mist eliminator, wherein the pressure is maintained across the plurality of evaporator spouts. The OTEC system also generates fresh water as a primary product and generates only enough electricity, as a secondary product, to operate the OTEC system itself.

Abstract: A distillation process and apparatus for recovering high purity aromatic products from a mixed aromatic hydrocarbon feedstock containing benzene, toluene and xylene by use of distillation towers integrated by heat exchange whereby substantial savings in operating costs and apparatus costs are realized. The distillation apparatus includes a benzene distillation tower and heat exchanger, a first toluene distillation tower and external heater, a second toluene distillation tower and heat exchanger and a xylene distillation tower and external heater, whereby the benzene distillation tower and heat exchanger are operably connected to the first toluene distillation tower and external heater and the second toluene distillation tower and heat exchanger are operably connected to the xylene distillation tower and external heater.

Abstract: In the multistage distillation of a methyl tertiary butyl ether reaction product comprising methyl tertiary butyl ether, tertiary butyl alcohol, methanol, isobutylene and water, the methyl tertiary butyl ether reaction product is separated in a primary methyl tertiary butyl ether distillation column into a lower boiling methyl tertiary butyl ether fraction and a higher boiling aqueous tertiary butyl alcohol fraction; the lower boiling aqueous tertiary butyl alcohol fraction is separated in a tertiary butyl alcohol distillation column into a vaporized overhead tertiary butyl alcohol fraction and a higher boiling water fraction; cooling water is charged to the reflux condenser for the tertiary butyl alcohol distillation column to liquify the vaporized, overhead tertiary butyl alcohol fraction and to convert the cooling water to wet steam, and the wet steam is independently charged to the reboiler for the primary methyl tertiary butyl ether distillation zone to supply the heat necessary for the distillation to b

Abstract: To heat the circulating reboiler streams of multiple distillation columns a fired reboiler is provided for a first column requiring the most heat. A portion of the bottoms from the first column is passed through the tubes of the heater in the fired reboiler and recycled to the first column as is normal. A slip stream is taken from the recycle after heating and passed on to provide heat by indirect heat exchange to a second reboiler and if desired other reboilers or heat exchangers. The slip stream may then be recycled to the bottoms of the first column directly or to the circulating steam of the first reboiler. A portion of the recycled slip stream can be taken as feed into the second column.

Abstract: For the regeneration of a liquid desiccant, a stripping agent is used which is liquid at ambient temperature and pressure, and forms a heteroazeotrope with water, along with the following steps: (a) distillation of the water-laden liquid desiccant to form vapor and partially regenerated liquid desiccant; (b) reboil partially regenerated liquid desiccant; (c) stripping of partially regenerated liquid desiccant during (a) and (b), using vaporized stripping agent; (d) a condensing of vapor the exiting the distillation, the condensation producing two liquid phases, one mainly water and the other mainly stripping agent; (e) heating the stripping agent-rich liquid phase exiting step (d) to generate a vapor phase which is richer in water than said liquid phase and a water-depleted liquid phase; and (f) returning the vaporized liquid phase exiting step (e) to step (c).

Abstract: A method of separating a liquid mixture wherein the liquid mixture is heated; the heated liquid mixture is supplied to a pervaporation membrane module to separate a permeable component of the liquid; a portion of non-permeated liquid is circulated through a circulation pipe into a liquid mixture feeding pipe before a heater, and the remaining portion of the non-permeated liquid is extracted to the outside of the system, and wherein the temperature of the liquid in the liquid mixture feeding pipe in which the non-permeated liquid has been mixed with the liquid mixture or in the circulation pipe for the non-permeated liquid, is measured, and when the measured temperature is out of a predetermined range, new supply of the liquid mixture and/or extraction of the non-permeated liquid is stopped.

Abstract: Reprocessing mixtures which contain organic solvents and constituents of low volatility and may contain water: includes introducing the mixture into a concentration apparatus of a solvent recovery system, concentrating the mixture in the concentration apparatus by evaporating off a portion of a readily volatile fraction and feeding this readily volatile fraction to a separation column. A portion of the concentrated mixture from the concentration apparatus is conducted away into a separation apparatus where the constituents of low volatility are separated off from the concentrated mixture and ejected from the solvent recovery system. The concentrated mixture is conducted away, freed from the constituents of low volatility, from the separation apparatus.

Abstract: To heat the circulating reboiler streams of multiple distillation columns a fired reboiler is provided for a first column requiring the most heat. A portion of the bottoms from the first column is passed through the tubes of the heater in the fired reboiler and recycled to the first column as is normal. A slip stream is taken from the recycle after heating and passed on to provide heat by indirect heat exchange to a second reboiler and if desired other reboilers or heat exchangers. The slip stream may then be recycled to the bottoms of the first column directly or to the circulating steam of the first reboiler. A portion of the recycled slip stream can be taken as feed into the second column.

Abstract: An extractive distillation agent comprising a mixture of polyoxypropylene glycols is fed to an extractive distillation column used for the distillation of propylene oxide contaminated with water, acetone and methanol to obtain an overhead distillate anhydrous propylene oxide fraction contaminated with reduced quantities of methanol and a heavier bottoms distillation fraction containing the polyoxypropylene glycols, water and acetone and some of the methanol introduced into the distillation column.

Abstract: A thermomechanically integrated distillation column and method for the separation of ethylene from ethane and other close-boiling light hydrocarbons. The column has a plurality of sections operated at successively lower pressures from a high pressure subcritical section to a superatmosphere bottoms product zone. Bottoms liquid from the high pressure and intermediate sections are flashed in respective cooling loops to about the pressure of the section of next lower pressure, vaporized in heat exchange with an overhead condensing zone and introduced to the top stage of next lower pressure section. Vapor from the intermediate sections and the bottoms product zone are compressed in respective compression loops and fed to the bottom stage of the section of the next higher pressure. External refrigerant can be supplied to the overhead condensing zone for trim as needed for control purposes.

Abstract: A distillation process is used to separate methanol from a mixture of methanol with methyl acrylate or methyl methacrylate, as well as from a mixture of methanol and water with methyl acrylate or methyl methacrylate with the use of an azeotropic solvent, which forms an azeotropic mixture with methanol. In distilling such a mixture by the use of a distillation column:(1) part of the condensate of vapors distilled over from the top of the distillation column top is returned to the top of the column;(2) the remaining condensate is separated into two layers;(3) the upper layer essentially composed of an azeotropic solvent from the two separated layers is fed to an intermediate portion of the distillation column;(4) the lower layer essentially composed of methanol from the above two separated layers is withdrawn from the distillation system; and(5) methyl acrylate or methyl methacrylate, or else, methyl acrylate or methyl methacrylate and water, are recovered from the bottom of the column.

Abstract: In the absorption of acetylene from a crude gas mixture containing mostly C.sub.2 hydrocarbons, a substantially acetylene-free liquid C.sub.2 stream is introduced into a mixing chamber located in the column between the feed points for the crude gas mixture and the absorption agent. The C.sub.2 stream is distributed into fine droplets as it enters into accumulated absorption agent in the mixing chamber, so that foam is not formed in the absorption column. The mixing chamber can be formed of a mixing tank integrated with a plate.

Abstract: Disclosed is a method and apparatus for recovering acetic acid from an acetic acid/water waste stream which includes a dehydration column into which the stream is fed and a liquid-liquid extraction system for recovering acetic acid from the condensate of the overhead stream of the dehydration column. Optionally, low pressure and/or high pressure absorber systems are provided to process vapor and/or liquid streams associated with the recovery system and/or the plant in which the acetic acid is used to further the recovery of acetic acid and reduce atmospheric pollution.

Abstract: A method for recovering volatile components from reformer effluent condensate and fusel oil in a methanol plant is disclosed. The fusel oil is stripped with steam to produce an overhead vapor stream of steam and stripped organic components which is recycled to the feed to the reformer. Also disclosed are a methanol plant with a fusel oil stripper; and a unitized stripper column for treating fusel oil and process condensate wherein steam containing volatile gases stripped from the process condensate is used to strip the fusel oil. The present invention improves yield and reduces or eliminates liquid fusel oil waste by recycling volatile organic components contained in the fusel oil to the feed of the reformer.

Abstract: The process of this invention is directed to recovering diluted aqueous latex paint collected during cleaning of latex paint manufacturing equipment. The collected aqueous diluted latex paint is subjected to vacuum evaporation at temperatures between about 120.degree. F. and 170.degree. F. at reduced pressures of at least about 25 inches of mercury vacuum to produce a distillate containing above 99% by weight water and concentrated latex paint reusable as latex paint or as blend in latex paint products.

Abstract: A discrete impure cresylic acid distillate fraction derived by fractional distillation of a natural cresylic acid feedstock from which tar bases and/or neutral oils have not been removed is subjected to extractive distillation with a polyhydric alcohol extractant and subsequent separation of the discrete cresylic acid fraction. The extractive distillation removes tar bases, neutral oils, undesirable phenolic substances, sulfur compounds, color-forming impurities and odor-imparting impurities.

Abstract: For separating ETBE and ethanol the following principal stages are employed:(1) Extraction of ethanol by water, the raffinate being ETBE saturated in water and the extract an ethanol/water mixture containing a small proportion of ETBE;(2) Concentration of the above mixture, the distillate being a mixture close to the ethanol/water azeotrope in composition and containing a very small proportion of ETBE;(3) Heteroazeotropic distillation of this distillate in two coupled columns with an overhead decanter, this distillation using ETBE as azeotroping agent; the residue of the first column being ethanol which is ca. 99% by mole and the residue of the second column being practically pure water, this water and the water recovered during the concentration stage being used as extraction solvent in stage (1).Stage (3) may be an ethanol dehydration unit using ETBE as dehydrating agent.

Abstract: A methanol refining column and method using an intermediate reboiler. Use of the intermediate reboiler reduces methanol production energy requirements. A side stream at or near a fusel oil takeoff point is heated in an intermediate reboiler by a low temperature heating medium (relative to a bottoms reboiler) and returned to the column at or near the fusel oil take-off tray. The take-off tray is operated at 85.degree.-110.degree. C., and 70-90 percent of the reboiler duty is supplied through the intermediate reboiler. The remaining heat load is supplied by a bottoms steam reboiler.

Abstract: A process and system for treating aluminum salt cake containing water soluble halide salts by contacting the salt cake with water to dissolve water soluble halide salts forming a saturated brine solution. Transporting a portion of about 25% of the saturated brine solution to a reactor and introducing into the saturated brine solution at least an equal volume of a water-miscible low-boiling organic material such as acetone to precipitate a portion of the dissolved halide salts forming a three-phase mixture of an aqueous-organic-salt solution phase and a precipitated salt phase and an organic rich phase. The precipitated salt phase is separated from the other phases and the organic rich phase is recycled to the reactor. The remainder of the saturated brine solution is sent to a multiple effect evaporator having a plurality of stages with the last stage thereof producing low grade steam which is used to boil off the organic portion of the solution which is recycled.

Abstract: In the absorption of acetylene from a crude gas mixture containing mostly C.sub.2 hydrocarbons by scrubbing with an absorbing agent, an externally produced mixture of about 10-70% by weight acetylene-free C.sub.2 hydrocarbons and about 30-90% by weight absorption agent is introduced in the absorption column, in order to prevent the formation of foam. The mixture is produced in a static mixer outside the absorption column, and is supplied from outside the column to a mixing tank installed between two plates within the column.

Abstract: A distillation system for recovery of volatile components of contaminated liquids used in an industrial process includes a tube assembly including outer tubes to which hot bottoms liquids are supplied and inner tubes to which process liquids are supplied for transfer of heat from the bottoms to the process liquids. From the tube assembly the two liquids are discharged into the still through separate, elongated, parallel discharge pipes. The process liquids discharge pipe is positioned above the bottoms liquids discharge pipe and an elongated, metal, angle plate is positioned as an inverted V between the two discharge pipes. Efficiency is improved over prior systems wherein process liquids are added to the still without being preheated by the bottoms fluids, and without the unique still intake manifold.

Abstract: Where side stream distillate strippers are used in the distillation of hydrocarbons, the required size of the distillation column and the amount of stripping gas or vapor required are reduced by passing components stripped from the distillates through a plurality of strippers in series, rather than directly back to the distillation zone.

Abstract: A method of recovering a solvent from a mother liquor in a system in which the mother liquor also contains non-volatile matter, volatile solute and volatile solvent, and the solute concentration is low, in which a heat pump distilling column (first column) is so operated as to work only as a concentrating section of a distilling column by feeding a mother liquor to the column bottom of the heat pump distilling column, contact of non-volatile matter with the concentrating section is prevented and the column bottom liquor is sent to an evaporator so as to separate the non-volatile matter by the evaporator, thereafter, a vapor from the evaporator is fed to a distilling column (second column), and distillates of first and second columns and bottoms of the second column are withdrawn as the products. The procedures described above are carried out under specific operation conditions.

Abstract: The method of obtaining a pure aromatic hydrocarbon from a hydrocarbon starting mixture includes extractively distilling the hydrocarbon starting mixture with a selective solvent; feeding the sump product of the extractive distillation through a first and second auxiliary boilers connected in series to form a cooled sump product at a temperature from 105.degree. to 120.degree. C.

Abstract: The invention relates to a distillation method and an apparatus for the concentration and purification of water-containing liquid chemicals. The distillation is performed using constant, predetermined distillation parameters.

Abstract: The invention relates to a distillation method and an apparatus for the concentration and purification of water-containing liquid chemicals. The distillation is performed using constant, predetermined distillation parameters.

Abstract: A system for continuously recovering renewable volatile compounds by boiling points from waste organic solvent with minimum energy loss, and an improved thin membrane distillation apparatus for efficient distillation of renewable volatile compounds from waste organic solvent and enforced discharge of the residue or sludge. The waste treatment system includes a thin membrane distillation apparatus, a cooling unit, a first distillation unit, and a second distillation unit connected in this sequence. Alternatively, the system includes two thin membrane distillation apparatus, a reduced pressure distillation unit, and a normal pressure distillation unit connected in this sequence. The thin membrane distillation apparatus includes a decompression chamber, a waste inlet, an outlet for volatile compound, an air-tight chamber, and a breaking mechanism with a screw head movable into the air-tight chamber.

Abstract: A system for the catalytic distillation production of alkylated aromatic compounds is provided wherein the vapor pressure of the olefin may be increased while maintaining the same olefin feed rate and aromatic to olefin ratio. In one embodiment a side stream from the vapor from the second column below the catalyst and olefin feed is condensed and rerouted to the aromatic make up stream from the reflux drum. The vapor pressure of the olefin in the lower end of the first column in the catalyst bed is thus increased which increases the equilibrium concentration of the olefin in the liquid phase. In another embodiment of the invention the effective driving force for the reaction is increased by injecting the olefin at different heights within the catalyst bed. If additional olefin is injected more catalyst bed height would be required, but the additional catalyst is more that offset by the increased throughput at the same overall olefin conversion.

Abstract: A process for separating an aromatic from a mixture containing also nonaroma includes distilling off the nonaromatics from the top of the extractive distillation column as a top product, drawing the aromatic and selective solvent from the extractive distillation column and subsequently separating the selective solvent from the aromatic in a separator column. The extractive distillation column is provided with a separate top product distillation column for recovery of a selective solvent residue from the separated nonaromatics. The entry hydrocarbon mixture is heated prior to admission to the extractive distillation column by an indirect heat exchange with selective solvent drawn from the separator column and heated to a temperature of from 130.degree. to 150.degree. C.The heated entry hydrocarbon mixture is depressurized to form a liquid phase and a vapor phase and these phases are separately fed into the extractive distillation column, the vapor phase entry point being below the liquid phase entry point.

Abstract: A method of separating and recovering components of a mixture having a gap in the range of miscibility and having organic compounds and water in a pervaporization process with the aid of membranes. The mixture is first separated into an organically loaded water phase and a water-saturated organic phase. Subsequently, the organically loaded water phase and the water-saturated organic phase are separately subjected to parallel, different pervaporization processes, resulting in retentates as water on the one hand and organic liquid on the other hand. The permeates that result during the pervaporization processes are subsequently returned to the mixture that is to be separated.

Abstract: The present invention provides an apparatus for preparing and treating a heavy oil extraction solvent. A solvent fraction is separated from a crude oil and combined with a slip stream of rerun solvent taken from an extraction process solvent recycle system. The solvent fraction and rerun solvent are fractionated to provide a purified extraction solvent. The purified extraction solvent is then utilized in the heavy oil extraction process.

Abstract: A method of separation of aromates from hydrocarbon mixtures by extractive distillation with a selective solvent, includes introducing a hydrocarbon mixture into the extractive distillation column, distillating out non-aromate components of the introduced hydrocarbon mixture from a head of the extractive distillation column, withdrawing aromates together with a used solvent from a sump of the extractive distillation column and supplying to a driving-out column, separating the aromates from the solvent in the driving-out column, withdrawing the aromates as a head product and the solvent as a sump product from the driving-out column, reintroducing the withdrawn solvent into the extractive distillation column, the withdrawing of the solvent from the driving-out column including withdrawing only part of the solvent with a high temperature required for the complete aromate driving-out from the sump of the driving-out column, while a rest of the solvent with a certain aromate content and a lower temperature is with

Abstract: Alkylaromatic hydrocarbons are produced in a process which comprises concentrating a feed aromatic hydrocarbon into a sidecut stream removed from a fractionation column. A feed acyclic olefin is then admixed with the aromatic hydrocarbon and passed through an alkylation reaction zone operated at optimum alkylation conditions. The reaction zone effluent is returned to the fractionation column to recover the product and to recycle untreated feed aromatics. This technique can be applied to hydrocarbon conversion processes in general to obtain benefits of catalytic distillation while operating the reaction zone at conditions not suitable for catalytic distillation. Hydrogen and other light gases are preferably separated from the reaction zone effluent by cooling and vapor-liquid separation external to the column.

Abstract: A distillation tower (1) has a plurality of liquid sidestream lines (5, 6, 7) and a multi-stage sidestream stripper (13) which includes a respective stripping section (14, 15, 16) for each sidestream line housed in a common, upright, cylindrical shell (28) which allows vapor to pass freely from each stage to the one above. Partial vaporization of each sidestream is achieved by applying a vacuum to the top of the stripper shell (point 21) and/or introducing strip gas at the bottom (point 20). Because the vapor passes serially through the stripping sections from the bottom of the stripper (13) to the top, the need to supply strip gas separately to the stripping sections and/or apply vacuum individually is avoided. The separation between the sidestream products is improved by including, in each stage, a rectification zone (22, 23, 24) positioned above the stripping section.

Abstract: The present invention provides a method for the recover of a solvent used in the production of a polyarylene sulfide according to which the deterioration of the solvent is low and the recovery rate is high, wherein a mixed liquid, mainly composed of the solvent used in the production of the polyarylene sulfide, and generated from the process of producing the polyarylene sulfide, is subjected to a flash evaporating operation to separate the mixed liquid into a flashed vapor (A) and a flashed residue (B), and then the flashed vapor is rectified (A).

Abstract: An evaporating process that alternate between different modes of operation, according to the characteristics of the product handled; the product is either force fed into the tube nest, or cascaded through it in a free-falling film.