Abstract: The pressure in a continuous high pressure polymerization system, in which ethylene, with or without comonomers, is polymerized under high pressures and temperatures and the unconverted amounts of gas are recycled through the high pressure recycle gas system into the polymerization system, is rapidly reduced to below the particular reaction pressure when predetermined limiting pressure and/or temperature values are exceeded or when other faults occur by opening one or more pressure-relief apparatuses mounted on the high pressure polymerization system and transferring the hot let-down reaction mixture from the polymerization system via one or more let-down lines through one or more separator systems into the atmosphere, by a process in which the high pressure polymerization system is divided into a plurality of isolated sections at the same time as the let-down process is triggered and only the section in which the let-down process is triggered is let down to the atmosphere.

Abstract: Process for the preparation of thermoplastic copolymers of .alpha.-methylstyrene and acrylonitrile by continuous bulk copolymerization ofA. 30 to 50 mol % of .alpha.-methylstyrene andB. 70 to 50 mol % of acrylonitrileat temperatures from 60.degree. to 120.degree. C. with average residence times of 4 to 12 hours in the presence of initiators which supply free radicals, carried out in at least two continuously operated mixed tank reactors, characterized in that 100 molar parts of a monomer mixture ofA.sub.0. 34 to 52 mol % of .alpha.-methylstyrene andB.sub.0. 66 to 48 mol % of acrylonitrileare fed continuously into the first tank reactor per unit time, and, with back-mixing, are copolymerized up to a conversion of 5 to 30 molar parts to give a copolymer of the compositionA.sub.1. 49 to 53 mol % of .alpha.-methylstyrene andB.sub.1. 51 to 47 mol % of acrylonitrile,and the mixture consisting of 70 to 95 molar parts of the monomers A and B and 5 to 30 molar parts of the copolymer of the composition A.sub.1 -B.sub.

Abstract: The present invention is directed to a continuous process which removes the 1 to 3% cyclic oligomers formed in the polycarbonate process and after hydrolysis of the oligomers recycles the resulting monomer for use in the reaction forming the polycarbonates. To remove the cyclic oligomers to a level so as to produce an improved polycarbonate product and to recover the oligomers in an economical manner for recycling in a continuous process, the selection of a solvent is unique and essential to achieve the continuous process. The solvent for the cyclic oligomers must be immiscible with water, must not react with an alkali and have a cohesive energy density of less than 90.

Abstract: In a copolymerization process of propylene, a mixture of unreacted propylene and ethylene is recovered. It is then fed to a distillation system which includes first and second distillation columns. The distillation system is operated in such a way that the temperature and pressure of the top of the second distillation column remain constant and an ethylene-propylene mixture can be recovered at a constant ethylene/propylene ratio from the top of the second distillation column. By using the thus-recovered ethylene-propylene mixture, the copolymerization reaction can be carried out under excellent control so that the ethylene-propylene copolymer can be obtained with uniform quality and properties.

Abstract: A reflux condenser attracts attention from the standpoints of improvement in productivity by increase in cooling capacity as well as saving in energy, and recently, it is frequently employed in particularly large-sized polymerization reactors. But, the well-known cooling method has a problem that the overall heat transfer coefficient of condensers lowers with the progress of polymerization to result in the reduction of heat-removing capacity and reduction of the stability of polymerization temperature control. In order to solve the above problems, in the present invention the temperature is controlled with the heat amount removed by the condenser as a control variable, coupled with intermittent purge of a part of the unreacted monomer from the reflux condenser.

Abstract: Disclosed herein is a method for controlling the polymerization temperature in a polymerization apparatus equipped with a cooling system in which steam, which has occurred in the presence of a volatile liquid medium in a reaction system, is condensed in a reflux condenser and the resulting noncondensable gas and condensate are then returned to the reaction system, thereby removing the polymerization heat. A portion of the noncondensable gas is recirculated to the cooling system. The flow rate of the noncondensable gas to be recirculated and the flow rate of a cooling medium to be introduced into the reflux condenser are controlled in accordance with the temperature of the reaction system.

Abstract: There is disclosed a process for recovering olefin monomers, e.g., C.sub.3 -C.sub.10 alpha-olefins, from a vent gas of a vapor phase process for polymerizing olefins. The method comprises passing the vent gas, obtained by purging a resin produced in the polymerization process with an inert gas, such as nitrogen, into contact with an adsorbent to effect the adsorption of an olefin monomer. Subsequently, the adsorbed monomer is removed by contacting the adsorbent with a second monomer having lower molecular weight than the adsorbed monomer.

Abstract: A novel process for production of polyethylene comprises polymerizing ethylene or a mixture of ethylene and a copolymerizable comonomer in the presence of a Ziegler-type catalyst at a pressure of 200 atm or more and at a temperature of 125.degree. C. or more, wherein an organic peroxide is added to the resulting polymerization product taken out of a reaction zone to deactivate the remaining catalyst. Formation of undesired oligomers or low-molecular polymers is prevented because the reaction does not proceed in the polymerization product taken out of the reaction zone. There is almost no retardation of the polymerization reaction even by the recycled use of the monomer separated and collected from the polymerization product.

Abstract: A continuous, liquid phase method for producing a polymer having a predetermined number of conjugated diene units per molecule in which (a) a first monomer stream is contacted with an organo-lithium compound, in a manner to intimately mix increments of monomer, containing the predetermined number of moles of conjugated diene, with each mole of organo-lithium and continuously mix and move the mixture through a first, elongated reaction zone to react the predetermined number of moles of conjugated diene with one mole of organo-lithium, (b) mixing the effluent from (a) with an alkyl-substituted aromatic hydrocarbon, an organo-alkali metal of potassium, rubidium or cesium and a tertiary amine to form a complex-initiator of the aromatic hydrocarbon, the alkali metal and the amine, (c) mixing the effluent from (b) with a second stream of monomer, in a manner to intimately mix increments of monomer, containing the predetermined number of moles of conjugated diene, with each mole of complex-initiator and continuously

Abstract: A circulation loop is provided between a point next to the outlet of an amorphous polyalphaolefin polymerization zone and a flash zone, carrying a stream of molten devaporized polymer product.

Abstract: Disclosed is a process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and by withdrawing vapour phase from the reaction vessel in a controlled amount by varying the amount of cooled surface available for condensing the vapors, condensing the vapors by contact with the cooled surface and returning the condensate to the reaction vessel. The process and apparatus also include a novel means for devolatilizing the product copolymer.

Abstract: A fluidized bed olefin polymerization process incorporates a recycle of a vent gas, containing unreacted monomers, from the product purge bin vessel to the polymerization reactor. The recycle of the vent gas minimizes the loss of the unpolymerized reactants, thereby decreasing overall process and product costs.

Abstract: An improved process for continuously producing ethylene-vinyl acetate copolymer containing 20 to 50 mole % of ethylene is provided. An aliphatic alcohol solvent is employed in the polymerization vessel. Ethylene vapor discharged from the polymerization vessel is introduced into the tubes of the lower part of a multi-tubular heat exchanger. Vinyl acetate is introduced into the upper part of the heat exchanger and caused to flow through said tubes, thereby effecting absorption and solubilization of ethylene into the vinyl acetate. The solubilized ethylene and vinyl acetate is passed to the polymerization vessel. The process of this invention permits the stable production of the copolymer over a long period of time.

Abstract: The process, which comprises a first stage for (co)polymerizing ethylene at 180.degree.-320.degree. C. and 300-2,500 bars in the presence of a Ziegler type catalytic system, a second stage for separation, a third stage for recycling unreacted monomers, and a fourth, recompression stage, is characterized by introducing into the stream of recycled monomer(s) during the third stage, at least one compound selected from the amides of the saturated or unsaturated organic acids containing from 12 to 22 carbon atoms, polyalkylene polyols containing from 4 to 500 carbon atoms, and compounds containing at least two epoxide functions, with a molecular weight greater than approximately 200. Preferably from 0.005 to 0.1 mole of the selected compound is introduced per ton of recycled monomer.This process makes it possible to avoid the formation of high molecular weight polymers in the recycle circuits.

Abstract: In a process for quench-cooled, vapor-phase polymerization of olefin monomer comprising (a) contacting an olefin monomer, or mixture of olefin monomers, with a polymerization catalyst in the presence of hydrogen in a reactor vessel to form polymer product, and (b) removing, condensing and recycling off-gas from such reactor, an improvement comprises separating entrained polymerizing solid fines from said off-gas and recycling such solids directly to the reactor without substantial continued polymerization of such solids while in the presence of a substantially different concentration of hydrogen than in the reactor.

Abstract: An improved process for recovery of ethylene from a polymerization process is described. A normally solid membrane is employed to recover an ethylene enriched gas stream from the polymerization vent gases. The ethylene enriched gas stream is recycled to the polymerization process.

Abstract: Isobutylene polymers are prepared continuously, in aliphatic C.sub.3 -C.sub.6 -hydrocarbons in the presence of soluble cationic polymerization initiators and coinitiators at from -40.degree. to 40.degree. C. and under from 0.01 to 10 bar, and the solvents and monomers vaporized during the polymerization are recycled, by a process in which the liquid stream of the monomer solution, containing 40-95, in particular 50-85, percent by weight of the monomers, the liquid streams of the recycle and of the coinitiator solution and the separate stream of the initiator solution are combined in a first zone containing the polymerization zone, and the resulting polymer solution is taken off continuously through a second zone vertically below the first zone. The liquid streams of the monomer solution, the coinitiator solution and the recycle can furthermore be fed into the first zone separately from one another.

Abstract: Ethylene is copolymerized with one or more 1-olefins under conditions of high temperature and pressure in the presence of an inert gaseous ratio modifier. As a result, liquid condensation which contributes to equipment damage and unsafe operation is avoided, and copolymer product density is readily controllable.

Abstract: Integral apparatus is disclosed for fluidized bed reaction systems wherein one or more of the following system component elements are positioned in a unitary reactor body: cooler means, compressor means and fluid recycle conduit means. Such cooler means also serve as gas distributor means acting to support the fluidized bed.

Abstract: Process for the production of polyphenylene oxide by means of the oxidative polymerization of 2,6-xylenol, with either oxygen or a gas containing molecular oxygen, in the presence of a catalyst, by continuously operating in a circulation system, and with the precipitation of the polymer in the liquid reaction medium.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to sufficient agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and devolatilizing the styrenic/alkenylnitrile withdrawn from the reaction vessel by a two-stage procedure including first adjusting the ratio of styrenic to alkenylnitrile monomer therein followed by heating to volatilize the volatile components and then separation of volatile components.

Abstract: A process for producing ethylene polymers or ethylene copolymers comprising the steps of: (a) continuously polymerizing ethylene or ethylene and an .alpha.-olefin in a reaction mixture at a pressure of at least 300 kg/cm.sup.2 and a temperature of at least 130.degree. C. in the presence of a catalyst composed of a compound of a transition metal of groups IVa and VIa of the Periodic Table and an organometallic compound of a metal of groups I to III of the Periodic Table; and (b) adding a polyalkylene glycol to the reaction mixture to deactivate the catalyst.

Abstract: Disclosed is a process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and by withdrawing vapor phase from the reaction vessel in a controlled amount by varying the amount of cooled surface available for condensing the vapors, condensing the vapors by contact with the cooled surface and returning the condensate to the reaction vessel. The process and apparatus also include a novel means for devolatilizing the product copolymer.

Abstract: Disclosed is a process for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to sufficient agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and devolatilizing the styrenic/alkenylnitrile withdrawn from the reaction vessel by a two-stage procedure including first adjusting the ratio of styrenic to alkenylnitrile monomer therein followed by heating to volatilize the volatile components and then separation of volatile components.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and by withdrawing vapor phase from the reaction vessel in a controlled amount by varying the amount of cooled surface available for condensing the vapors, condensing the vapors by contact with the cooled surface and returning the condensate to the reaction vessel. The process and apparatus also include a novel means for devolatilizing the product copolymer.

Abstract: There is provided a method for terminating a gas phase olefin polymerization reaction with a kill gas such as carbon monoxide or carbon dioxide. The method involves the use of coast-down flow of recycle gas during a failure of the power source of a compressor to carry kill gas into the reaction medium. The method is particularly adaptable to a fluid bed reactor system.

Abstract: A process is described for increasing the space time yield of polymer production in a fluidized bed reactor employing an exothermic polymerization reaction by cooling the recycle stream to below its dew point and returning the resultant two-phase fluid stream to the reactor to maintain the fluidized bed at a desired temperature above the dew point of the recycle stream.

Abstract: Disclosed is a process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers.

Abstract: Nylons are prepared by a continuous process in which, in a precondensation zone, an aqueous solution of a salt of a dicarboxylic acid of 6 to 18 carbon atoms and a diamine of 6 to 18 carbon atoms is heated to 250.degree.-300.degree. C. under superatmospheric pressure, with simultaneous vaporization of water and formation of a prepolymer, the prepolymer and the vapor are separated, and the former is fed into a polycondensation zone and condensed under superatmospheric pressure of from 1 to 10 bar and at from 250.degree. to 300.degree. C., wherein the aqueous salt solution is condensed under superatomspheric pressure of from 1 to 10 bar in the first third of the tubular precondensation zone provided with baffles, until the degree of conversion is not less than 93%, and the prepolymer and the vapor phase are brought into intimate contact with one another in the remaining two thirds of the precondensation zone.

Abstract: Nylons are prepared by a continuous process in which, in an evaporator zone, an aqueous solution of a salt of a dicarboxylic acid of 6 to 18 carbon atoms and a diamine of 6 to 18 carbon atoms is heated to 250.degree.-300.degree. C. under superatmospheric pressure, with simultaneous vaporization of water and formation of a prepolymer, the prepolymer and the vapors are separated continuously, the vapors are rectified and the entrained diamines are recycled, and the prepolymer is fed to a polycondensation zone and subjected to polycondensation under superatmospheric pressure of from 1 to 10 bar and at from 250.degree. to 300.degree. C., wherein the aqueous salt solution is heated under superatmospheric pressure of from 1 to 10 bar during a residence time of less than 60 seconds, with the proviso that, on leaving the evaporator zone, the degree of conversion is not less than 93% and the water content of the prepolymer is not more than 7% by weight.

Abstract: A process for the manufacture of vinyl chloride polymers or copolymers by microsuspension polymerization of vinyl chloride or vinyl chloride and up to 30% by weight, based on the total monomer content, of .alpha.-olefinically unsaturated monomers copolymerizable with vinyl chloride comprising the steps of:(1) dispersing the monomer or the monomer mixture in water in the presence of from 0.1 to 3% by weight, based on the total weight of the monomer content, of microsuspension dispersion auxiliaries and from 0.001 to 3% by weight, based on the total weight of the monomer content, of microsuspension monomer - soluble radical - initiators;(2) homogenizing said dispersion so that monomer droplets mostly having a mean diameter of from 0.1 to 3 .mu.

Abstract: Polyethylene and an ethylene-.alpha.-olefin copolymer are produced by polymerizing ethylene or a mixture of ethylene with an .alpha.-olefin having 3 to 18 carbon atoms by use of a coordination polymerization catalyst containing a transition metal compound and an organometallic compound, deactivating said catalyst by adding a copolymer of at least one monomer selected from the group consisting of vinyl monomers having a carbonyl group represented by the formula: ##STR1## wherein R.sup.1 represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms; R.sup.2 is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; M represents a metal element; and m represents the valence of M,or maleic anhydride with ethylene to be mixed with said catalyst, separating unaltered monomers from the polymer mixture.

Abstract: A process for producing an ethylene copolymer which comprises polymerizing a predominant amount of ethylene and a minor amount of an alpha-olefin having 4 to 10 carbon atoms in the gaseous phase in the presence of a catalyst composed of (A) a transition metal catalyst component and (B) an organometallic compound of a metal of Groups I to III of the periodic table; characterized in that the copolymerization is carried out under the following conditions (i) and (ii),(i) at least 1 mole, per mole of ethylene, of a gaseous saturated hydrocarbon having 3 to 6 carbon atoms is caused to be present in the gaseous phase copolymerization system, and(ii) the gaseous mixture containing the unreacted olefin which has been discharged from the gaseous phase copolymerization system is cooled to a temperature at which the mixture is not liquefied, and the cooled gaseous mixture is recycled to the gaseous phase copolymerization system.

Abstract: A fluid bed reactor, suited for recycling a fluidizing gas containing, in suspension, particles of solid material; comprising a gas distributor consisting of a doubleconed body or of a series of concentrical cones provided on their lateral surfaces with ribs or fins forming gas inflow channels shaped in such a way and with such an inclination as to allow the passage of the solid particles entrained in the gas flow, and such as to hinder the outflow of the solid material that has been fluidized, when the flow of the gas is interrupted.

Abstract: Polyethylene is produced in at least one reactor under a pressure of 800 to 2500 bars and a temperature of 150.degree. to 350.degree. C., and the reaction mixture exiting the reactor through an expansion valve and supplied to a separator under a pressure of 50 to 400 bars is cooled by passing a flow Q of the mixture through a turbine. The turbine comprises at least one stage with a fixed nozzle and a bladed wheel having a rotation speed of between 12,000 and 40,000 r.p.m. Ethylene discharged from the separator is recycled to the inlet of a compressor, and the discharge from the compressor is supplied to the reactor.

Abstract: Ethylene is copolymerized in the gas phase, for example in a fluidized bed, using a gaseous mixture comprising ethylene, at least one olefine monomer containing at least 4 carbon atoms, an inert gaseous diluent and, optionally, hydrogen at a total absolute pressure of at least one MN/m.sup.2. The comonomer preferably contains 6 or 8 carbon atoms. The partial pressure of the comonomer may be in the range from 1 kN/m.sup.2 up to 550 kN/m.sup.2. The inert gaseous diluent typically has a partial pressure of at least 250 kN/m.sup.2 and forms 20% molar of the gaseous mixture. The inert gaseous diluent may be nitrogen and is preferably ethane.

Abstract: An improved method for the production of polyphenylene ethers is disclosed. The method comprises oxidatively coupling monohydric phenols in the presence of a complex catalyst and in a liquid medium which is a solvent for the monomer and catalyst and a non-solvent for the polyphenylene ether. The polyphenylene ether precipitates to form a slurry of particulate solids which is then washed with an aqueous solution of a chelating agent to remove catalyst residue.

Abstract: A process for producing aromatic polyester polycarbonate particles from a methylene chloride solution of an aromatic polyester polycarbonate comprises continuously supplying the methylene chloride solution of an aromatic polyester polycarbonate to a particle-forming tank, heating it while maintaining it in a suspended state in water to evaporate methylene chloride and to form aromatic polyester polycarbonate particles, subjecting at least a part of the resulting aqueous slurry withdrawn from the particle-forming tank and containing the aromatic polyester polycarbonate particles to wet pulverization treatment and recycling the treated slurry to the particle-forming tank.

Abstract: The disclosure is directed to an improvement in the gas phase polymerization of propylene using a Ziegler-Natta catalyst in the presence of hydrogen wherein the gaseous propylene is withdrawn from the reactor, cooled and condensed and returned as a liquid to the reactor in order to regulate the polymerization temperature. The amount of the gaseous phase in the condenser-cooler-accumulator system is kept constant by regulating the amount of gaseous phase returned to the reactor.

Abstract: A process for preparing a polyamide is provided. The polyamide is prepared by causing a dicarboxylic acid and a diamine to polycondensate directly under an atmosphere of an inert gas at atmospheric pressure. The polycondensation reaction is mainly carried out in two diamine component-adding steps, one step comprising adding part of the diamine to the molten dicarboxylic acid until the molar ratio of the diamine to the dicarboxylic acid is brought to within the range of from 0.900 to 0.990 while raising continuously the temperature of the reaction mixture to a temperature not exceeding about 5.degree. C. above the melting point of the object polyamide and the other step comprising adding the remainder of the diamine to the reaction mixture maintained at a temperature higher than about 10.degree. C., but not exceeding about 35.degree. C. above the melting point of the object polyamide until the overall molar ratio of the diamine to the dicarboxylic acid is brought to within the range of from 0.995 to 1.005.

Abstract: An improved process for the preparation of fiber-forming polycaprolactam by polymerizing .epsilon.-caprolactam, and an aqueous extract containing .epsilon.-caprolactam and caprolactam oligomers, which extract has been obtained by extracting polycaprolactam with water, wherein the aqueous extract contains from 0.1 to 5.0% by weight of oligomers of caprolactam, based on the monomeric caprolactam in the aqueous extract.

Abstract: Production of spinnable polyhexamethylene adipamide of high molecular weight from adiponitrile, hexamethylene diamine, water and additives, preferably continuously in a reaction cascade and in a finisher as the final stage, catalytically accelerated by catalysts as disclosed.It has now been discovered that polyamides can be produced from dinitriles, diamines and excess water in the presence of catalysts selected from the group consisting of: (1) oxygen-containing phosphorous compounds; (2) oxygen-containing boron compounds; (3) acidic oxygen-containing sulfur compounds; and (4) hydrogen halide and ammonium or ammonium alkyl salt thereof.

Abstract: In a process for polymerizing a monomer capable of being formed, upon polymerization, into a solution having an upper cloud point of the corresponding polymer in a reaction medium being liquid under the reaction conditions, the polymerization being carried out under such conditions that the resulting polymer dissolves in the reaction medium; the improvement wherein(i) the polymerization is carried out in a polymerization zone at a temperature above the upper cloud point of said polymer solution and under conditions which enable the polymer solution to be separated into two phases,(ii) the polymerization is carried out under stirring conditions which maintain the two phases under said phase-separating conditions in a dispersed and mixed state, and(iii) the resulting polymer solution is sent to a separating zone located independently of said polymerization zone, thereby separating it into two phases in the separating zone at a temperature above the upper cloud point, and thereafter, the polymer-rich liquid phas

Abstract: An improved process for the continuous preparation of polycaprolactam, in which .epsilon.-caprolactam is partially polymerized, with the addition of a water-containing agent and acetic acid or propionic acid as a chain regulator, at a nylon-forming temperature, in a mechanically mixed zone in a vertical tubular reactor through which the reaction mixture flows downwards, and is then polymerized further, in additional heat exchange zones, until the desired degree of polymerization is reached, and polycaprolactam is then discharged as a melt, wherein a gaseous mixture of caprolactam, water and acetic acid or propionic acid is removed at the top of the tubular reactor and is fed to the middle of a column, water is removed at the top of the column, the bottom of the column is maintained at from 125.degree. to 145.degree. C., and the mixture obtained at the bottom of the column, and comprising caprolactam, acetic acid or propionic acid and a small amount of water, is recycled to the top of the tubular reactor.

Abstract: Process and device for cooling a mixture of polymer and monomer from a reactor in which ethylene is polymerized or copolymerized at a pressure greater than 1,000 bars between a pressure-reduction valve located downstream of the reactor and a medium pressure separator. The cooling is achieved by injecting monomer at a pressure below that of the separator using a device with a nozzle distance S.sub.1 and corresponding cross-section A.sub.1 the mixture from the reactor passes, a convergent mixing zone in which the mixture is mixed with the monomer injected, which is supplied at a flow rate q, and a diffuser of throat distance S.sub.3 and corresponding cross-section A.sub.3, which makes it possible to bring the mixture to the pressure of the separator. The dimensions of the device are such that the ratio Q/A.sub.1 is between 0.20 and 1.35 t/hr.mm.sup.2 and the ratio ##EQU1## is between 0.1 and 0.3 t/hr.mm.sup.2.

Abstract: In polymerizing an olefin, for example, in a polymerization reactor with a reflux condenser, a gas mixture withdrawn from the polymerization reactor is first washed before it reaches the heat transfer surface of the reflux condenser to remove active catalyst particles and polymer particles entrained therein and then condensed to obtain a condensed liquid, and the condensed liquid is returned to the polymerization reactor whereby the heat generated in the polymerization reactor is efficiently removed without causing any clogging of pipes, etc.

Abstract: In the continuous catalytic polymerization of isobutylene, the exothermic heat of reaction is removed by vaporizing unreacted hydrocarbons, compressing and condensing the vaporized hydrocarbons to yield a liquid condensate at a pressure and temperature higher than that in the reaction zone, reducing the pressure on the liquid condensate to reduce its temperature to that of the reaction zone, separating any vapors thus formed and recycling the liquid condensate to the reaction zone. The process provides an energy efficient means of controlling reaction zone temperature. The process can be employed when using either a fluidized or fixed bed catalytic system.

Abstract: A solid product resulting from the nucleated growth of the product on solid material of either the same or different composition and having a density higher than the reaction medium is formed from one or more liquid phase reactants by a method which comprises tangentially introducing the liquid phase reaction medium into the lower, smaller end of an inverted, frusto-conical reactor-separator, thereby imparting an upward swirling motion to the reaction medium in the reactor-separator, the horizontal velocity at the bottom of the reactor-separator being sufficiently large to cause fluidization of larger, solid product particles and concentration of them in the central lower portion of the reactor-separator and the vertical velocity at the top of the reactor-separator being sufficiently small to avoid carry-over of the smaller solid particles but sufficiently large to concentrate them in the upper portion of the reactor-separator; at least periodically recovering the larger, solid product particles in spherical

Abstract: The efficiency of a rectifying zone for the recovery of diamine vapor from water vapor being separated from a reaction zone in which a polyamide-forming salt is being heated to form a prepolymer is improved by adding a dicarboxylic acid to the reflux water at the top of the rectifying zone.