Abstract: Polyether glycols, especially poly(tetramethylene ether) glycol (PTMEG) having a narrow molecular weight distribution of about 1.90 to 2.07, or dispersity of 1.50 to 1.90, are made by a process wherein the low molecular weight fraction in unit operations using at least one short-path distillation evaporator. In these units, PTMEG is subjected to temperatures in the range of 150.degree.-190.degree.C. with the hold-up time varying between 10-200 seconds. The required vacuum to force the separation of the low molecular weight PTMEG varies between 0.001 mm and 1.0 mbar. PTMEG residue from the distillation unit is also characterized by its low water content and low concentration of oligomeric cyclic ethers.

Abstract: 2-(4-Isobutylphenyl)-propionic acid is purified by subjecting it to a vacuum rectification, in which the temperature is below the decomposition temperature of the acid.

Abstract: A film-type evaporator has a vapor chamber, a rotor rotating therein, at least one evaporating surface extending outwards from the rotor axis and a heating chamber rotating therewith and sealed with respect to the vapor chamber. The starting product is fed onto the evaporating surface close to the rotor axis and spreads outwards in film-like manner due to the centrifugal force on the evaporating surface. A uniform film thickness is achieved in that the evaporating surface is a curved blade surface, which is formed by a generatrix substantially parallel to the rotor axis and whose axial extension is limited by upper and lower stop ledges, and that the concave side of the evaporating surface is directed in the circumferential direction of rotation of the rotor.

Abstract: An apparatus for thickening liquids with solid contents has a container receiving the liquid and a vapor outlet and a heater, which is positioned in the liquid column in the container. The heater is constructed as a rotor rotating in the container and is formed from a plurality of substantially parallel plates arranged with a limited axial spacing and extending outwards from the rotor axis, every second space between adjacent plates forming a heating chamber sealed with respect to the liquid, while the spaces located between the same close to the rotor axis and on the circumference thereof are open towards the container interior.

Abstract: In a thin film evaporator for the evaporation of solutions, colloids, suspensions, or the like, to concentrates, which has a heatable cylindrical evaporator casing coupled with a rotary drive, which evaporator casing has a feed inlet at one end, in the form of a feed distributor that runs on bearings and is coupled with a rotary drive, and at the other end has a concentrate discharge, the axis of the evaporator casing is arranged horizontally. The distal end of the feed distributor can reach the inside surface of the evaporator casing to within less than 2 cm. Wiper elements can work together with the effective surface of the evaporator casing. This thin film evaporator makes possible an optimal setting of the retention time of the process material to be treated in the evaporator casing and has the effect that the thickness of the layer of the process material changes very little over the entire axial length.

Abstract: Film-type evaporator for thickening liquid products with a container having a vapor outlet, a drive shaft introduced into the latter from above for a rotating rotor with at least one conically upwardly widening heating surface, onto whose inside the product is fed in the vicinity of the smaller diameter and the product spreads in film-like manner towards the larger diameter and is fed there as a concentrate into the container, and on whose outside is guided the heating medium supplied and removed through the hollow drive shaft.

Abstract: A falling film evaporator includes a chamber having a top and bottom tube plate; a plurality of vertical tubes each having an interior and exterior surface and extending through the chamber and being supported by the top and bottom tube plates; an inlet at the chamber for feeding heating medium into the chamber; a distributor above the tubes for feeding liquid to be evaporated into the tubes and for causing the liquid to be distributed as a falling film along the interior surface of the tubes so as to evaporate the liquid and generate vapor as the liquid passes in heat exchanging relationship with a heating medium present at the exterior surface of the tubes; a vapor space defined by a circumferential wall below the tubes; a plurality of vertically elongated spaced elements having a substantially U-shaped cross-section with inwardly pointing vertical edges for receiving the evaporated liquid and the vapor, the elements being arranged in a circumferential wall below the tubes within the vapor space spaced from

Abstract: Fatty alcohols are separated from a solution containing alkyl polyglycosides (APGs) and alcohols, wherein the alcohols and the alkyl groups of the APGs contain 10-18 C atoms and wherein the mean degree of polymerization of the (APGs) is 1.05-1.4 by distilling said solution at 160.degree.-200.degree. C. under a pressure of 0.1-20 hPa in a thin layer evaporator having a Reynolds number of 30-18,000.

Abstract: A water desalination apparatus which is constructed of a main housing which includes a condensation chamber and a vapor chamber located above the condensation chamber. Brackish water is to be supplied into the vapor chamber with this brackish water to produce a vapor which is to be removed by a centrifugal compressor arrangement into the condensation chamber. The condensed brackish water from the vapor chamber is to flow through a mass of thin-walled tubes to be eventually discharged into the ambient. The exterior wall of these tubes is located within the condensation chamber and it is on the walls of these tubes that the distilled water vapor is to collect and condense and flow from the condensation chamber to a collection source.

Abstract: A distillation system has a degassing tank, a distiller for generating vapor of raw water taken from the degassing tank, a heater for heating the vapor from the distiller to convert the vapor into a high temperature and pressure vapor, a hydrophobic porous membrane through which the vapor from the heater flows, and a heat transfer unit provided in the distiller for effecting heat exchange between the vapor from the membrane member and the raw water from the degassing tank. The structural elements such as the heat exchange unit, piping, etc., with which the vapor from the membrane or the condensate thereof is brought into contact are made of titanium or titanium alloy.

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: The present invention is directed to a method for recovering 2-chloropropionic acid so that this compound can be separated in a high-purity form. According to the method, crude 2-chloropropionic acid is heat-treated in the presence of a metal compound at a temperature in the range of 130.degree.-180.degree. C. where dichloro derivatives are contained as impurities or at a temperature not exceeding 160.degree. C. where no dichloro derivatives are contained. The metal compound is then removed at 160.degree. C. or lower. Final purification is thereafter conducted to obtain 2-chloropropionic acid as a high-purity product.

Abstract: A wiped film evaporation process for reducing the amount of residual organic polyisocyanate, especially toluene diisocyanate, in a polyurethane prepolymer reaction product mixture. An inert sweeping gas is added to the evaporation process, preferably after first passing through a holdup volume of the prepolymer which has passed through the evaporation zone.

Abstract: A process for the production of tocopherols (T) and tocotrienols (T3) from palm fatty acid distillates (PFAD). The process includes converting free fatty acids and glycerides in PFAD into alkyl esters, then separating T and T3 from the alkyl esters and other impurities. The T and T3 are concentrated by ion-exchange and further concentrated by distilling the resulting product. Specific catalysts and optimum temperatures for the process are included. The resulting purified tocopherols and tocotrienols are useful substances, exhibiting antioxidant and physiological activities.

Abstract: A film evaporator formed by a cylindrical body section (50) with a heating jacket (53) and angled scraping blades (84) mounted on a rotatable shaft (76) to move the thickened material downwardly through the evaporator. Below the body section (50) is an inverted frusto-conical section (62) containing inclined scraping blades (86) also mounted on the shaft (76) and a smaller diameter lower body section (64) through which the thickened product can be discharged by a screw (93) of opposite hand to the scraping blades (84). The screw (93) is carried on a lower shaft (88) which is journalled to the shaft (76) so that the shafts can be rotated independently and in opposite directions.

Abstract: Concentration of solutions containing methanol and either dimethyl carbonate or methyl t-butyl ether may be effected by a composite membrane including a dibromobutane cross-linked poly(4-vinyl pyridine) bonded to a porous layer of polyacrylonitrile on a polyester backing.

Abstract: A solvent-containing biological material specimen is dried in a vacuum chamber with solvent evolving during the drying cycle being condensed in a refrigerated cold trap. During the drying cycle, communication of the drying chamber with the vacuum pump with which the chamber is evacuated, selectively is established or interdicted in response to raising or lowering of the vacuum condition in the chamber with respect to an initially set predetermined vacuum condition. Evolving of solvent from the specimen proceeds during interdiction by way of "cryopumping" due to the differential in pressure between the chamber and the refrigerated trap. Thus maximized solvent recovery in the trap is achieved, and carry over of solvent to the vacuum pump wherein its presence would be contaminating of the pump oil is for practical purpose eliminated.

Abstract: Purification of 6-aminocapronitrile by reduction of tetrahydroazepine with a hydride, and then distilling the 6-aminocapronitrile at a pot temperature of less than about 200.degree. C.

Abstract: A vacuum drying method wherein a solution of a material to be dried which has been adjusted to 1-50 centipoise, is supplied to a steam-heated long tube, solid-vapor mixture of powdery dry material and vapor produced in the tube is blown out under reduced pressure, and the powdery dry material and vapor are separated so as to obtain powdery dry material.

Abstract: An apparatus for dissolving oil or PCB which exists in the electrical insulation of parts to be cleaned, wherein a solvent is evaporated during a heating phase by an evaporator located with the parts in an autoclave. The solvent vapor condenses on the parts and penetrates into the electrical insulation to form an oil or PCB-solvent mixture. The apparatus provides for a plurality of intermediate pressure reductions which are carried out in the autoclave, and during each intermediatre pressure reduction the solvent is simultaneously evaporated from the oil or PCB-solvent mixture, directly from the autoclave. That is, during each of the pressure reductions, the solvent supply is discontinued and the mixture circulated through a circulating line. Following the completion of each intermediate pressure reduction, the pure oil or PCB present in a condensate vessel is pumped out by an intermediately located feed pump through a connecting line and into a reservoir.

Abstract: The method of preparing and operating a heat-exchanging membrane of plastic material as the evaporating and condensing surfaces in a still includes treating the evaporating surface to be wettable by the distilland, and includes selectively washing the condensing surface which is unwettable by the by the distilland in order to promote efficient accumulation of condensed droplets and efficient heat transfer through the membrane to the evaporation surface. Washing liquids of either similar or disimilar chemical composition relative to the condensed vapor are recycled to the upper region of the condensing surface to facilitate washing of the surface by the downward movement of accumulated droplets of condensed vapor.

Abstract: A wiped film evaporation process for reducing the amount of residual toluene diisocyanate in a polyurethane prepolymer reaction product mixture. An inert sweeping gas is added to the evaporation process, preferably after first passing through a holdup volume of the prepolymer which has passed through the evaporation zone.

Abstract: A process for treating naphthenic fractions with a caustic blend of sodium and potassium hydroxide, preflashing the naphthenic fraction to remove water and then flashing the dewatered fraction to remove the neutral oils and the materials that were not formed into the acid salts. The naphthenic salt mixture is then quenched and acidified so as to recover the naphthenic acids. Naphthenic acids recovered from the process of the present invention have acid numbers which are generally higher than the naphthenic acids heretofore produced from the corresponding feed streams. The process provides for the flashing of the water which otherwise would cause foaming and not permit the recovery of the acid salt for the enhanced separation of the naphthenic acids.

Abstract: A counter-current contacting device which includes a number of features which increase the efficiency and/or increase the pressure differential across the device is disclosed. Systems for reducing the alcohol content of an alcohol containing beverage or wine, for stripping aroma and flavor from a fruit juice and for desulphuring a liquid containing dissolved sulphur dioxide are also disclosed. Each of these systems incorporate a counter-current contact device of the invention.

Abstract: A thermal system includes a plurality of heat exchangers in series and the same number of flash tanks in series is interposed between two subsequent effects of a multiple effect evaporating system for sulfate black liquor. The liquor is indirectly heated in the heat exchangers by vapor produced by step-by-step expansion of the same liquor in the flash tanks and additionally by steam from an external source. To decrease the viscosity of the black liquor it is heated to a temperature of 190.degree.-200.degree. C. and retained in a reactor vessel for 10-20 minutes.Preferably the flash tanks and the heat exchange elements are positioned on top of each other within a shell to form an integral construction in which the vapor compartment of each flash tank is directly connected to the vapor compartment of a corresponding one of the heat exchange elements.

Abstract: A method and device for removing, from liquid such as water, dissolved volatile substances and gases when water is being distilled or evaporated. Feed water of a distilling apparatus or evaporator is heated to a sufficiently high temperature, whereby part of the feed water changes into vapor, and is then conducted to a purifying device. The feed water is discharged in the purifying device in the form of a thin film. The gaseous substances present in the feed water or liquid are separated by a separator device provided in the purifying device, and then conducted away through a connector provided on the purifying device.

Abstract: A falling film evaporator in which some plate elements have their upper portions surrounded by a hood to prevent feed liquor from contacting hot vapor generated in the evaporator and exchanging heat therewith by direct contact. Other elements are located outside the hood.

Abstract: A process for the removal of water from a lower alkanesulfonic acid-water mixture by causing the mixture to run down the internal walls of two vertical evaporator columns operated in series, is disclosed herein.

Abstract: A falling film evaporator having vertical outer tubes with closed upper ends connected to an upper tube plate disposed in the lower region of the evaporator. Other parallel tubes are disposed inside the outer tubes and are connected to a lower tube plate under the upper tube plate. The evaporator also has a mechanism for distributing the material to be evaporated onto the upper ends of the outer tubes in such a way that the material flows down along the tubes and forms a film on the external surface of the tubes. The space between the tube plates, in which the ends of the outer pipes are located, is divided by an intermediate wall into an inlet and an outlet compartments. Heating steam is fed to the inlet compartment. Clean condensate is recovered from the inlet compartment and contaminated condensate from the outlet compartment.

Abstract: In order to dissolve oil or PCB which exists in the electrical insulation of parts to be cleaned, a solvent is evaporated during a heating phase by an evaporator located with the parts in an autoclave. The solvent vapor condenses on the parts and penetrates into the electrical insulation to form an oil or PCB-solvent mixture. In the heating phase, a plurality of intermediate pressure reductions are carried out in the autoclave, and during each intermediate pressure reduction the solvent is simultaneously distilled out of the oil or PCB-solvent mixture, directly from the autoclave. That is, during each of the pressure reductions, the solvent supply is discontinued and the mixture circulated through a circulating line. Following the completion of each intermediate pressure reduction, the pure oil or PCB present in a condensate vessel is pumped out by an intermediately located feed pump through a connecting line and into a reservoir.

Abstract: Heating elements formed by joining a pair of plates around most of their peripheries are provided with an internal partition which separates upper and lower internal spaces within the element so that separate streams of condensate are discharged from the element. A plurality of such plate elements can be used in a falling film condenser.

Abstract: A device for removing the volatile components of a polymer in a polymer train includes a hollow pipe which defines an interior chamber, a pair of flanges mounted on opposite axial ends of the pipe, a heat jacket mounted on the pipe and disposed to surround the pipe, a plurality of band heating elements mounted on the outer peripheral surface of the heat jacket, and an arrangement of fin elements disposed in the interior chamber of the pipe to contact the polymer flowing through the pipe. Heat from the heating elements is distributed by the heat jacket over the axial length of the pipe and is transferred to the fin elements to heat the polymer flowing through the pipe. The fin elements may be in a cruciform arrangement within the interior chamber of the pipe. A method of removing the volatile components includes forming a thin film of polymer and heating and distributing the heat evenly on the thin film of polymer so that the volatile components may be vaporized.

Abstract: Process for the fractional distillation of a liquid under vacuum comprising preheating a liquid to be distilled, forming under vacuum the preheated liquid into a first series of thin sheets of falling liquid to be distilled, and a cooling liquid into a second series of thin sheets of falling cooling liquid, the thin sheets of the first series being alternately arranged with the thin sheets of the second series, in close proximity to one another. Part of the liquid to be distilled is vaporized and passed to the thin sheets of cooling liquid to form liquid distillate and separately recovering the liquid distillate with the cooling liquid and the non-vaporized part of the liquid.

Abstract: A distilling and desalination apparatus comprising an evaporation chamber and a condensing chamber in which the evaporation chamber through a cooling circuit communicates by way of heat exchange with the condensing chamber and rotates in relation thereto. The evaporation chamber is constructed to form a thin fluid film on the inner surface of the evaporation chamber during rotation, surplus water being slung out along the edge and into channels and led tangentially to the rear by blades. The cooling circuit comprises a condensing portion and an evaporation portion, the fluid being evaporated along the inner surface of the coolant condensing portion, and fluid vapors being condensed along the outer surface of the coolant condensing portion, whereupon the drops of fluid are slung outwards and collected.

Abstract: An evaporator which is formed, in combination, of a first evaporator of a centrifugal falling-film type; and a second evaporator having a shape formed of a heating side wall portion of a downward-pointing conical configuration, a cover portion defining at least one opening, through which a liquid to be treated is charged and resulting volatile components are discharged, and a bottom portion defining at least one opening permitting discharge of an evaporation residue. A scraping agitator is built in the second evaporator. The side wall portion is externally wrapped with a pipe or the like, whereby a heating medium is caused to pass therethrough for heating the side wall portion. The evaporation residue discharge opening of the first evaporator is connected to the opening of the cover portion of the second evaporator.The above evaporator is suitable to recover a volatile component from a high-viscosity liquid containing tar-like substances. It can achieve a high recovery rate.

Abstract: In a falling film evaporator of the vertical-tube type in which liquid to be evaporated is supplied at the top on the outer surface of vertical heat exchanger tubes and the heat medium is supplied to the heat exchanger tubes at the bottom for flow inside the same, at least one larger tube element than the heat exchanger tubes is disposed between and fixed to tube plates at the both ends of the group of tubes to stabilize the group of tubes against tension and especially compression stresses.

Abstract: Deodorizing and/or physical refining of relatively small, varying charges of high-boiling liquids, viz. fatty acids, edible oils, fats, glycerides and other high-boilding esters, is conducted continuously in a single-stage or multi-stage falling-film column (20) through the trickle passages (23) of which stripping steam is passed in counter-current flow. In the supply conduit (15, 15', 15", 15'") leading to the falling-film column and in the discharge conduit (30, 30', 30", 30'") leading away from the bottom (26) of the falling-film column a plug-flow of the liquid is maintained. Upon a change of charge the fresh liquid to be treated is normally introduced into the supply conduit--without any blank charge--directly following the liquid of the preceding charge. Charging of the liquid onto the deflector (22) in the head (21) of the falling-film column is interrupted for a short period of time when the front of the liquid of the fresh charge has reached a check valve (16) disposed adjacent said deflector.

Abstract: A process for the recovery of alcohols and hydrogen sulfide from a thiophosphate containing mixture is disclosed.

Abstract: An evaporator includes heating elements which are part of a thin skin providing the evaporator vessel wall, supporting the skin for internal and external pressure, and a top portion of the vessel. A liquor distributing plate is supported on the heating elements, with a liquor inlet donut-shaped conduit disposed above the liquor distributing plate. The heating elements are radially disposed within the vessel, and are supported at the bottom by a ring which engages the bottoms of the heating elements, and a vertical axis tube extending from the vessel bottom to the ring, the tube having a plurality of through-extending openings formed in it. The vapor outlet for the vessel is concentric with the heating elements and the liquor distributing perforated plate. Heating fluid (e.g. steam) is introduced into the interior volumes of the heating elements adjacent the tops thereof, and a vent is provided adjacent the bottoms.

Abstract: A method for passivating the surface of the strippers of the urea plants, where the temperatures are very high, where the pressures range from 120 to 240 Kg/cm.sup.2 and where the effluent process flow from the synthesis reactor undergoes one or more falling-film evaporations, preferably in countercurrent with a driving gas consisting of NH.sub.3 or CO.sub.2, characterized by the fact that the passivation is carried out by means of a sinergistic combination of oxygen, preferably injected into the bottom of at least one stripper, and of a second passivating agent, preferably injected into the process flow entering the head of at least one stripper, wherein said second passivating agent is injected in the liquid state or as a liquid solution, before or contemporaneously to the start of the evaporation.

Abstract: A multiple effect evaporator system and a process for concentrating a process liquid wherein evaporated process liquid from one effect serves as heating fluid in an adjacent effect. Low energy heating fluid in vapor form is fed to an evaporative surface condenser where it is condensed and collected as clean and foul condensate. Coolant for the evaporative surface condenser is provided in the form of process liquid from one of the effects. Prior to passage into the evaporative surface condenser, the process liquid is cooled. In the cooling circuit of the evaporative surface condenser, the process liquid absorbs the heat of condensation of the heating fluid and subsequently rejects the heat into a counter flowing air stream. The process liquid is thereafter heated and returned to another of the multiple evaporator effects.

Abstract: A falling-film process and apparatus for the cocurrent evaporation of a solution is disclosed. The process utilizes a tube-bundle heat exchanger in which the upper ends of the individual tubes of the tube-bundle are closed. Apertures, preferably in the form of slots, are formed adjacent the closed-end of the individual tubes. A liquid heel is maintained above the highest of said apertures and flows into the interior of the tubes through said apertures. Upon entering the tubes the liquid and any vapor released therefrom flows cocurrently in a downward direction. The vapors released from the liquid are recycled to a point above the liquid heel through conduit means separate from the individual tubes.

Abstract: A method of producing substantially pure dialkyl maleate by separating monoalkyl maleate from dialkyl maleate in a short residence time distillation zone while minimizing reversion of the monoalkyl maleate to alkanol and maleic anhydride and without having to neutralize the monoalkyl maleate.

Abstract: A method and apparatus of controlling a rotating vacuum evaporation system is disclosed. The rotating flask, containing the medium to be evaporated, is buoyantly supported in a liquid bath and the relative elevation between the flask and the liquid level in the bath is measured. The relative elevation is utilized as the control signal to control the addition of fluid medium to the flask, and to shut off the system when desired.

Abstract: An evaporator comprises a plurality of substantially parallel plates mounted for rotation about a common axis and in which provision is made for a condensible vapor to flow across a first face of each of said plates and for a liquid, at least a portion of which is to be evaporated, to flow across the second face of each of said plate, which plates are arranged to be rotatable at such a mean acceleration, measured in a radial direction with respect to said axis of rotation, greater than the acceleration due to gravity, said first face of each of said plates has a surface designed to discourage formation of a continuous liquid film thereon. The evaporator may be used to concentrate solutions, e.g. of depleted brine or aqueous caustic soda.

Abstract: A thin film evaporator consists of an enclosure defining a vapor space, a level drive shaft running into the enclosure and a rotor fixed to the shaft and having an axis of rotation disposed horizontally when in operative position, the rotor being made up of spaced coaxial conical evaporator elements, whose evaporation space communicates with the vapor space. The feed to be evaporated is supplied at one end of the rotor at the inner circumference of one or more conical evaporator elements thereof. Such evaporator elements are placed together in pairs so that they taper outwards with the evaporating faces thereof facing each other, so as to form a collection trough at their outer edges for the concentrate. The feed spreads out in the form of a film from the inner edge or edges for the elements and is taken up in the respective collection trough as a preconcentrate.

Abstract: A process for the continuous production of boiler feed water from process waters in the oil extraction industry during which salts and hydrocarbons are removed from the water, without Fe.sup.++ precipitating. The heavy hydrocarbons are mechanically separated, the volatile hydrocarbons are separated from the water, by means of a thermal degassing, and the low boiling and the non-condensable hydrocarbons are separated in a shower evaporation step with downstream vapor compression, wherein the low boiling non-condensable hydrocarbons are evaporated with the waste water within the shower evaporator and the non-condensable hydrocarbons then are drawn off from a downstream separator. A salt-free oxygen-free pure water is removed from a separator.

Abstract: A thin layer evaporator comprises a container forming a body, a container cover on the one side, a drive shaft projecting into the container from the opposite side, a rotor fixed to the drive shaft and which has one or more conically outwardly widening evaporator areas and whose evaporator chamber is connected to the body, as well as a heating chamber separated from the body. The starting product is fed to the inner periphery of the evaporator areas, spreads outwards therefrom in a thin film and the concentrate is removed on the outer periphery by means of a draw-off pipe. In order to be able to absorb dynamic forces in a vibration free manner, the drive shaft is partly constructed as a hollow shaft and is mounted on a fixed spindle projecting into the container and rotor.

Abstract: A method and apparatus for converting a long tube vertical evaporator to a falling film evaporator in a manner which permits salvaging most of the long tube vertical evaporator structure. The bottom chamber of the existing evaporator is extended to define a flash chamber intermediate the existing heat exchanger chamber and the bottom chamber. A vapor riser conduit is provided for directing vapor from the flash chamber to the vapor separation chamber positioned above the heat exchanger chamber. A recirculation conduit is provided for directing liquid from the bottom chamber therethrough into a distribution chamber which is provided above and in communication with the upper ends of the heat exchange tubes positioned in the heat exchanger chamber. The distribution chamber is preferably provided with a plurality of spray nozzles which communicate with the recirculation conduit to evenly distribute a film of liquid downwardly through the heat exchange tubes.

Abstract: A free flow evaporator of the falling film type has the heating elements disposed in a circular configuration so that each extends radially a distance less than the interior radius of the evaporator cylindrical vessel. Heating vapor is introduced concentrically into the top of the vessel and passes into the tops of the heating elements, and condensate is withdrawn from the bottoms of the heating elements in the vessel. Excess vapor passes through a vapor vent in the bottom of the vessel. The boiling liquid, such as black liquor from paper pulp processing, is introduced through a header above an annular channel with a perforated plate bottom, the perforated plate being disposed on top of the heating elements. The evaporated liquid vapor passes radially outwardly in the vessel, and then upwardly, and is discharged from the top of the vessel and passes to the top of another vessel (providing another effect), to provide heating vapor to the other vessel.