Abstract: A process of purifying titanium tetrachloride by first refluxing titanium tetrachloride (TiCl4) with copper powder, rendering the impurities of vanadium, niobium and antimony nonvolatile, and then in a single step fractionally distilling the refluxed mixture to effectively and substantially reduce any arsenic, tin, niobium and vanadium in the titanium tetrachloride.

Abstract: The invention consists of a cost-effective process and facilities for obtaining high quality drinking water and high-grade brine as a chemical raw material from raw water regardless of how much salt it contains. When combined with a thermal power-generation process, the plant also produces electric power with a fuel utilization of over 85%.

Abstract: An evaporative process employing an undulating flexible membrane (4) as an evaporative surface onto which a vaporizing gas (2) such as, but not limited to, air, contacts a liquid solution (1, 5) such as, but not limited to, water, and evaporation occurs. The membrane (4) is supported (3) with sufficient laxity to permit wavelike undulating motion of the membrane brought about primarily by the evaporative airflow (2) itself. The differential flexing and motion of the undulating membrane (4) results in a breaking and peeling away of any normally fouling scaling or plugging solids which have precipitated or accumulated on the membrane surface (4). The undulation of the flexible membrane (4) thereby providing a self cleaning action. The self cleaning action of the membrane (4) assures successful application to evaporative processes with solutions (1, 5) which are prone to scaling, fouling, plugging or solutes buildup.

Abstract: Nitrogen trifluoride (NF3) containing less than 10 parts-per-million molar impurities, e.g., tetrafluoromethane (PFC-14), is disclosed. Azeotropic and extractive distillation processes using entraining agents for separating NF3 and PFC-14 from each other and from mixtures with other electronics industry materials are disclosed.

Abstract: A method for distilling a raw material liquid containing (meth)acrylic acid substantially free from azeotropic solvents, collected with a collection agent from a mixed gas obtained by gas phase catalytic oxidation reactions which includes feeding to a distillation column the raw material liquid which temperature is substantially equal to that of the entrance place in the column.

Abstract: A process for the recovery and purification of cyclobutanone from a crude product mixture obtained from an oxidation product mixture resulting from the oxidation of cyclobutanol to cyclobutanone in the presence of water. The process provides for the recovery of cyclobutanone in a purity of at least 90 weight percent by a combination of distillation steps.

Abstract: A solar still for producing fresh water including a device, adapted to absorb solar radiation and to contain water to be distilled; a condensation surface on which vapor, produced by heating up of water of the device can condense; a fresh water collector that trickles down the condensation surface in which said device includes an impermeable membrane that is flexible, kept stretched, of a dark color, exposed to the sun, and arranged in a shade, a hydrophilic fleece forming a covering for said membrane, supplied with water by capillary action and gravity; a device for recovering formed brine arranged at the bottom of said fleece; wherein said impermeable membrane and its hydrophilic fleece constitute the wall of an evaporation chamber that is elongated, a transparent sheltering element installed underneath; wherein said transparent sheltering element is a closed space and an inner face of a wall thereof constitutes said condensation surface; and a blower which is associated with an apparatus for producing a fl

Abstract: A purification tower for purifying liquid by contacting the liquid with gas, the purification tower including: (a) a shell; and (b) a plurality of baffles, each of which is fixed to an internal surface of the shell, (i) said each baffle having a flat upper surface and a plurality of openings are formed in each of the baffle so that the liquid and the gas pass through the openings; (ii) any adjacent pair of the baffles are arranged so that a bottom of the shell is covered by the pair of the baffles viewing in an longitudinal direction of the shell. The present invention thus configured can provide a process and an apparatus for the purification of even an organic compound containing a readily-blocking substances, which are capable of continuously purifying such an organic substance over the long time without discontinuing operations.

Abstract: Volatile siloxane oligomers are removed from an emulsion containing siloxane polymers and volatile siloxane oligomers prepared by emulsion polymerization of volatile siloxane oligomers by continuously feeding the emulsion to a continuous flow device for vaporizing liquids, continuously feeding a stripping gas to the continuous flow device, continuously removing an overhead fraction of volatile siloxane oligomers from the continuous flow device, and continuously removing an unvaporized bottom fraction from the continuous flow device of an emulsion containing siloxane polymers which is substantially free of residual volatile siloxane oligomers used to prepare the emulsion. A benefit of the method is that the viscosity of the siloxane polymer in the emulsion before the emulsion is fed to the continuous flow device is substantially the same as the viscosity of the siloxane polymer in the emulsion after the emulsion is removed from the continuous flow device.

Abstract: A method to separate ethanol from a solution containing sulfuric acid and ethanol which employs a vessel in which ethanol is humidified from a gas. By adding a gas to a solution containing sulfuric acid and ethanol in the vessel a gas is utilized to form humidified ethanol. Heat is provided to the solution to replace heat of vaporization of the humidified ethanol to maintain a substantially constant thermal equilibrium condition within the vessel to compensate for the energy of ethanol evaporation. The gas humidified with ethanol is then parted from the vessel to remove ethanol from the solution. The sulfuric acid, substantially devoid of ethanol, is likewise removed from the vessel. The ethanol humidified gas is thereupon separated from the ethanol to provide ethanol and a gas containing ethanol.

Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boilers and high boilers is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b), which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).

Abstract: In distillation of easily polymerizable compounds such as (meth)acrylic acid and (meth)acrylic esters using a distillation unit, a liquid having substantially the same composition with that of a liquid surrounding a constitutive member placed in the distillation unit is sprayed by a spraying and supplying device. The liquid supplied by the spraying and supplying device preferably has a wetting liquid rate (of the sprayed and supplied liquid, a flow rate of a liquid attaching to and wetting the constitutive member) of 0.5 m3/m2hr or more relative to the surface area of the constitutive member. The liquid supplied by the spraying and supplying device preferably contains a polymerization inhibitor. It is also preferred to supply a gas containing molecular oxygen to the distillation unit. This process can effectively inhibit the polymerization of the easily polymerizable compounds, which polymerization is liable to occur inside the distillation unit.

Abstract: A method and apparatus for water degasification and distillation in an apparatus having a container for a reservoir of water to be degassed and distilled, a relatively small boiler adjoining the container and having a feed water conduit connecting the container and boiler so that a selected water level in the container will fill the boiler to the same level, a coiled tube condenser within the container immersed in the water therein, the condenser coil having a vertically disposed longitudinal axis, a second conduit in the boiler connecting the space above the water level therein to the inlet of the condenser so that steam flows from the boiler to the condenser, an outlet on the condenser extending through a container wall for discharging the condensed steam as degassed distilled water, a heater in the boiler for heating the water therein, a motor driven stirrer axially of the coiled tube condenser for generating a swirling movement of the reservoir water with formation of steam bubbles therein and an ozone ge

Abstract: Method for extracting an ingredient from plant, animal or mineral by heating water to create a vapor, contacting the ingredient under a state of decompression with the vapor, condensing the vapor by passing the vapor over one or more surfaces cooled by a thermoelectric cooler, and collecting the condensate.

Abstract: In a process for the preparation of (meth)acrylic acid from a mixture which contains (meth)acrylic acid and a solvent having a boiling point above the boiling point of (meth)acrylic acid by distillation of the mixture in a column which is connected to an evaporator and has a stripping section and a rectifying section, between which the mixture is fed in, and a side take-off for the (meth)acrylic acid, a polymeization inhibitor is fed into the column in the region of the top of the column and in the region of the side take-off, that amount of polymerization inhibitor which is introduced in the region of the top of the column being smaller than the amount introduced in the region of the side take-off.

Abstract: A desalination apparatus and method utilizing solar energy provided with a solar heat collector for heating a heating medium with solar energy, a heat exchanger cooperating with an evaporation can so as to subject the heating medium and raw water in the evaporation can to heat exchange and generate water vapor therein, a condenser cooperating with a raw water tank so as to receive the vapor from the evaporation can, cool the vapor by subjecting the vapor and raw water in the raw water tank to heat exchange and obtain distilled water.

Abstract: A method and system for handling foul condensate containing Hazardous Air Pollutants (HAPs) in a cellulose pulp mill has enhanced energy efficiency and lower cooling water usage, while complying with the Cluster Rules and other environmental regulations. The condensate is fed countercurrently to stripping vapor in the stripping column to produce a HAPs vapor and a clean condensate. Part of the clean condensate is fed from the stripping column reboiler, and the HAPs-rich vapor is directed to the reboiler to at least partially condense while vaporizing the clean condensate into the clean vapor (stripping vapor). The pressure of the stripping vapor is increased, such as utilizing a steam ejector, to about 0.1-30 psig and then is used as the stripping vapor in the stripping column. The non-condensed HAPs-rich vapor is fed to an external condenser, and the dirty condensate from the external condenser and the dirty condensate from the reboiler, are returned to the stripping column.

Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boils and high boils is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b). which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).

Abstract: A process for the distillation of vinylaromatic monomers in the presence of 4-tert-butylcatechol (TBC) and oxygen, wherein no aromatic nitro or amino compound is present in any effective amount. The process is particularly suitable for destabilizing and purifying styrene which has been stabilized with 4-tert-butylcatechol (TBC) for transportation.

Abstract: The preparation of polyamides, their oligomers or mixtures thereof, where appropriate with other reaction products, takes place by reacting amino nitrites (A) and, where appropriate, other polyamide-forming monomers and/or oligomers with water (D) in a reactive distillation, wherein the reaction product (P) is discharged from the bottom of the reactive distillation apparatus, and ammonia (N) which is produced and, where appropriate, other low molecular weight compounds which are produced, and water, are taken off overhead.

Abstract: An apparatus and a method for separating a liquid mixture by fractional distillation. The apparatus includes at least two chambers with a conduit from the lower portion of a chamber which contains liquid to the upper portion of an adjacent chamber, a source of pressurized vapor, and a conduit from the source of pressurized vapor to the lower portion of the chamber which contains liquid. Flow of the liquid from the chamber which contains liquid is effected by introducing pressurized vapor into the liquid, thereby reducing the density of the liquid, pumping the liquid into the upper portion of the adjacent chamber. The two or more chambers can be housed in a single circular vessel, where the chambers are separated by partitions radiating from the center of the cylindrical vessel to the wall of the vessel. The apparatus can have a reduced height compared to conventional distillation columns.

Abstract: In a process for the purification of (meth)acrylic acid and/or its ester using a distillation unit containing a distillation column, a multitubular reboiler and a pipe connecting these elements, an oxygen containing gas is supplied from a least one point in regions between the distillation column and an inlet of the multitubular reboiler and/or in regions between the inlet and an inlet side tube sheet of the multitubular reboiler. This process can effectively prevent the formation of polymerization products and can stably purify (meth)acrylic acid and/or its ester over a long time.

Abstract: A method for starting up a distilling column destined to handle an easily polymerizing compound-containing solution characterized by supplying at the start of the operation of the distilling column a polymerization inhibitor to the bottom liquid of the distilling column having a temperature of not higher than 80° C. Further, by supplying a reflux liquid through the top of the distilling column or the middle stage of the column prior to the start of the temperature elevation of the distilling column, thereby preventing the polymerization of the easily polymerizing compound more effectively.

Abstract: Process for the recovery of fluorinated sulphonic acid including the step of subjecting the spent acid to heat treatment with stepwise or continuously increasing temperature, withdrawing at least two fractions during the heat treatment; and recovering the fluorinated sulphonic acid from each fraction.

Abstract: For the fractionation of viscous silicones, oily or polymeric diorganosilicones with a chain length of between 2 and 10 000 are separated into a top and a bottom product, preferably continuously in an extracting column, using compressed hydrocarbons such as ethane, propane and n- or i-butane, or mixtures thereof, at temperatures of between 25 and 250° C., pressures of between 20 and 500 bar and a gas density >160 kg/m3. To avoid viscosity problems, either an organic solvent in the form of a C5-8 alkane or up to 85 wt. % of the compressed gas (mixture) can be added to the starting materials prior to fractionation. With this process, high-quality viscous silicone fractions are obtained, which have a chain length of 200 to 10 000 and/or a viscosity of 100 to 500 000 mPas, and whose total oligomer content D4 to D20 is less than 0.05 wt. %.

Abstract: An apparatus and a method for removing residual monomers from a slurry containing a polyvinyl chloride. The apparatus has a cylindrical tower with plural perforated plates provided in a vertical direction in the tower, plural chambers formed on the perforated plates serving as their bottom surface, slurry introducing portions provided at two or more of the chambers, flow-down sections provided between the perforated plates to allow the slurry to sequentially flow down from the perforated plate of an upper chamber to the perforated plate of a lower chamber, a steam introducing port at a bottom portion of the tower, a deaerating port at a top portion of the tower, a slurry discharging port at a chamber below a chamber having the slurry introducing port, and hot water ejectors directly under the perforated plates directed at least toward the lower surface of the perforated plates.

Abstract: A method that employs a dilute solution, such as a dilute hydrogen peroxide solution, and concentrates the dilute solution to a yield a concentrated solution. A concentrated solution prepared by the method of the invention is useful as a rocket fuel, a laser fuel and industrial and laboratory chemical reagents.

Abstract: The system for the recovery of water from urine aboard spacecraft includes a urine intake and pretreatment unit, a unit for water reclamation from urine and a condensate purification unit. The unit for water reclamation from urine is made on the basis of a rotary multistage vacuum distiller, each stage of which is formed by at least one heat-transfer plate and comprises an evaporation zone and a condensation zone. The stages of the distiller are separated from each other by separation plates, a chamber for collecting condensate and noncondensable gases being disposed downstream of the last stage and communicated with all the condensation zones of all the stages through water seals of condensate overflow and openings for the removal of noncondensable gases in disks mounted in the condensation zones.

Abstract: A process for separating a fraction containing low and middle boilers from a mixture of low, middle and high boilers, which involves treating the mixture in a column with low-boiler vapor in the bottom, so that the middle-boiling component accumulates in the low-boiler vapor and can be obtained at the temperature level of the low-boiling component.

Abstract: In a process for the separation by rectification of (meth)acrylic acid from a mixture containing (meth)acrylic acid and an inert hydrophobic organic liquid having a boiling point higher than that of (meth)acrylic acid as main constituents and also lower aldehydes as secondary constituents, a primary amine and/or a salt thereof are added.

Abstract: A method of remediating water contaminated by dissolved gases and liquids and suspended particles wherein the contaminated water is collected into a closed container without filling the container and heated to a temperature below the boiling point of water. Negative pressure is then drawn on the closed container without causing the water in the container to boil, whereby the dissolved gases and liquids in the contaminated water, having a boiling point lower than water, will evaporate out of the water into the head space above the water in the container. Finally, atmospheric air and/or oxygen are allowed into the container to push the vapors out of the head space of the container.

Abstract: A method and apparatus for separating volatile from nonvolatile substances, separation of volatile substances, one from the other, and for performing various chemical reactions. In particular, an apparatus which performs these functions utilizing a combination of above ambient temperatures and above one inch of mercury vacuum within a rotating vessel. The apparatus uses a conventional rotary vacuum seal. The apparatus, however, operates well above the maximum operating temperature of the conventional rotary vacuum seal by isolating and cooling the conventional rotary vacuum seal.

Abstract: A process for recovering hexamethylenediamine (I) from a mixture (II) including(I) hexamethylenediamine,(III) hexamethyleneimine,(IV) a compound selected from 2-aminomethylcyclopentylamine and 1,2-diaminocyclohexane,(V) an imine,(VI) adiponitrile and 6-aminocapronitrileincludes distilling(a) a mixture (II) to obtain(a1) a low boiling fraction (III),(a2) a medium boiling fraction (VII) (I), (IV) and (V), and(a3) a high boiling fraction (V) and (VI),(b) a mixture (VII) to obtain(b1) an overhead product (IV), and(b2) a mixture (VIII) (I) and (V) as bottom product, and(c) a mixture (VIII) to obtain(c1) (I) as overhead product, and(c2) a bottom product (V).

Abstract: The invention relates to a process for producing high purity isobutene from a hydrocarbon cut essentially comprising olefinic hydrocarbons containing 4 carbon atoms per molecule including isobutene, also butene-1 and butene-2 compounds in a ratio which substantially corresponds to the thermodynamic equilibrium. The process comprises passing the cut into a distillation zone (3) associated with a hydroisomerisation reaction zone, the bottom product of the distillation zone comprising butene-2 compounds being passed into a skeletal isomerisation zone (2) where the linear butenes are at least partially isomerised to isobutene, at least part of the principal effluent from the skeletal isomerisation zone being recycled upstream of the reactive distillation zone (3).

Abstract: A process and system are provided for the separation of a fermentation process byproduct into its constituent components and for the subsequent recovery of those constituent components. The process is remarkably simple--requiring only 1) heating of a mixture containing the byproduct so as to separate the oil from a base component of the byproduct to which the oil is bound, followed by 2) recovering the base product, oil, and possibly other substances such as molasses from the mixture. The process can be performed on a large scale and in a continuous fashion using a mechanical separator to recover fibers from a heated mixture to produce a solids stream and a liquor stream and by then removing oil and insoluble substances from the liquor stream in an evaporator assembly.

Abstract: Processes for the purification and color stabilization of crude maleic anhydride by distillation in a batch or continuous distillation column.

Abstract: 5-Formylvaleric esters are prepared in a yield of not less than 90% by distillation of a formylvaleric ester mixture of 5-formylvaleric ester and either 3- or 4-formylvaleric ester or a mixture of 3- and 4-formylvaleric esters, where the ester radicals of the respective formylvaleric esters are identical, wherein the 3- or 4-formylvaleric ester or a mixture thereof is separated from the 5-formylvaleric ester in a distillation column at a pressure in the range from 2 to 100 mbar and a temperature of not above 150.degree. C. (measured as the temperature at the bottom of the column) and the esters used are the corresponding methyl or ethyl esters, where the purity of the 5-formylvaleric ester is not less than 98% and, as impurity, 4-formylvaleric ester is present in an amount of not more than 100 ppm.

Abstract: In an atmospheric pipestill stripping process where steam is utilized as the stripping gas to strip bottoms and side stream products, the improvement comprising utilizing methanol or a methanol and steam mixture as said stripping gas. In a refinery atmospheric pipestill stripping process utilizing a stripping gas, said process comprising utilizing a gas selected from the group consisting of methanol and a mixture of methanol and steam as said stripping gas.

Abstract: A process for preparing refined acrylic esters, the process including steps of distilling an acrylic ester containing stream in the presence of hydroquinone or substituted hydroquinone, at a concentration in the range of 200 to 5000 ppmw, wherein the distillation is carried out in the presence of 0.001 to 1.0 % v, on the vapor phase, of oxygen.

Abstract: A process for the continuous oligomerization of ethylene to produce linear alpha olefins by oligomerizing ethylene in a polar phase comprising a solution of transition metal catalyst system at oligomerization conditions including a temperature and pressure greater than the critical temperature and pressure of ethylene. The resulting hydrocarbon phase containing oligomers and unreacted ethylene is subjected to physical treatment which tends to render the ethylene a nonsolvent for oligomers and thereby produce a liquid stream rich in unreacted ethylene which may be recycled to the oligomerization reaction zone by pumping.

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: The invention concerns a process for isomerising a feed containing essentially hydrocarbons, preferably paraffins preferably containing 5 and/or 6 carbon atoms per molecule, in which said feed is treated in a distillation zone comprising an exhausting zone and a rectification zone associated with an isomerisation reaction zone, in the presence of an isomerisation catalyst and a gas stream containing hydrogen, characterized in that the reaction zone is at least partially internal to the distillation zone, and wherein the hydrogen-containing gas is fed by a dedicated gas distributor to the bottom of at least one catalytic bed within the isomerization reaction zone.

Abstract: In a method for the desalination of seawater, there is evaporated and condensed the seawater, within a primary system, and a secondary medium, preferentially untreated water, within a compressor-containing, self-contained secondary system spatially separated from the primary system. The seawater is evaporated by heating in the presence of the secondary medium previously heated in the compressor at excess pressure, the latter medium is evaporated in the secondary system through condensation of the seawater vapour and the seawater vapour is led through a cyclone separator.

Abstract: A method and apparatus permits concentration of a water-miscible organic liquid in a mixture of such liquid and water, with recovery of a desired concentrate of the water-miscible organic liquid and water, and a relatively clean water containing only a very low content of the water-miscible organic liquid which enables disposal of the water in sewage systems, the method and apparatus thus enhancing the ability to satisfy environmental concerns; the method has particular application to the recovery of a reusable glycol/water mixture from diluted spent aircraft deicer fluid (ADF).

Abstract: Materials which are not themselves storage-stable at room temperature are made suitable for storage by mixing them with a carrier substance and spray drying the resulting mixture so as to form particles containing both the material and the carrier substance in which the carrier substance is in an amorphous, i.e. glassy or rubbery, state. Formation of such a composition greatly enhances stability. The material stored may be a biological material such as an enzyme, the components of a chemical reaction such as reagents for carrying out an assay, or even viable biological cells.

Abstract: This invention relates to a process for working up the alcohol-containing wastewater which is obtained in the hydrolysis of silanes of the general formula IR.sup.1.sub.a SiCl.sub.b (OR.sup.2).sub.4-a-b (I),whereR.sup.1 are hydrogen atoms or identical or different monovalent, unsubstituted or halogen-substituted, SiC-bonded C.sub.1 -C.sub.18 -hydrocarbon radicals,R.sup.2 are identical or different monovalent C.sub.1 -C.sub.10 -hydrocarbon radicals,a is 0, 1, 2 or 3, on average from 0.3 to 1.9, andb is 0, 1, 2, 3 or 4, on average from 0.0 to 3.0,with the proviso that the sum a+b is on average at most 3.5, for the preparation of silicone resins, wherein, in the first step, the wastewater is made alkaline by addition of alkali and, in the second step, the alcohol is removed from the resulting alkaline solution or suspension by injection of steam.

Abstract: A method of concentrating chemicals for semiconductor devices, which includes the steps of heating a sample container by using a high-energy light source, vaporizing the chemicals by injecting a high-temperature gas into the sample container through an injection opening in the sample container and discharging the vaporized chemicals by the pressure of the gas through a gas outlet formed on the sample container. An apparatus of concentrating chemicals for semiconductor devices includes a sample container having a sample-supply window, a gas-injection opening and a gas outlet. A high-energy light source heats the sample container and a gas-supply source supplies the gas through a gas-injection opening in the sample container. A gas-heating device located between the sample container and the gas-supply source heats the gas provided by the gas-supply source.

Abstract: Improved kugelrohr or apparatus for distilling or separating liquids. It includes a rugged, reliable air oven and drive unit with numerous safety features. One or more external guards eliminate burn hazard and risk of accidental contact. A thermal isolation support isolates the oven from its rest surface. A grounded heating element eliminates shock hazards. The oven is fitted with a grommet or bushing to support a flask connected to one or more additional flasks in a series. The outlet of the last flask in the series is connected to a drive tube via a flexible coupling. The drive tube is connected to a rotary bearing assembly mounted on a drive unit. The oven and the flasks may include impellers for circulating air to enhance heating efficiency.

Abstract: A process for separating a multi-component mixture containing solid or liquid organic components by treating the mixture with a gaseous entraining agent comprising a superheated carrier fluid containing a lower monohydric alcohol or a lower monohydric alcohol and water to cause constituents of the multi-component mixture to become entrained in the gaseous entraining agent, and separating the gaseous entraining agent containing constituents of the multi-component mixture from the multi-component mixture.

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.