Abstract: The invention relates to a continuous-working process and apparatus for replacing the liquid in a liquid suspension of a fibrous material with another liquid by forming of this material a bed on a moving filter surface and by displacing the liquid present in this bed with the other liquid. The bed of material is formed on a cylindrical filter surface installed in a vertical orientation below the liquid surface in a container and conveys it continuously forward filtration and several successive liquid displacements effected by maintaining a hydrostatic pressure difference across the formed bed, which is conveyed continuously horizontally forward, and through it there flow liquids horizontally during the filtration and liquid displacement.

Abstract: First and second washing machines are utilized to recycle plastic and cellulose from disposed diapers. The disposed diapers are loaded into the first washing machine and, while being agitated, are washed in water, alkali and soap. During washing, the cellulose becomes separated from the plastic. The cellulose is drained out of the first washing machine with the water, leaving the plastic in the first washing machine. The plastic is then cleaned in the first washing machine. A pump transfers the cellulose and water to the second washing machine. In the second washing machine, the cellulose is washed in alkali and soap while being agitated. The second washing machine has a screen for retaining the cellulose therein, while passing the water and waste material.

Abstract: A method and apparatus for the treating of fiber suspensions in the pulp and paper industry and particularly to a method and apparatus for washing fiber suspensions.The method is characterized in that the fiber suspension is fed into the treatment apparatus, the desired process is carried out and the suspension is discharged from the apparatus in such a way that the fiber suspension is fed directly from the pipework to the treatment ducts mounted between the end plates of the rotational parts of the washer thus forming substantially extensions of the pipework. The fiber suspension is treated in the ducts and thereafter the treated suspension is discharged from the ducts by feeding yet untreated suspension to the apparatus.The apparatus includes a plurality of axially elongated treatment ducts (9) arranged in the form of a ring around an axis of rotation. The ducts are radially limited by filter surfaces (10, 11) and in the direction of the end walls divided by partition walls (8).

Abstract: A method and apparatus for improving the treatment of a gas containing fiber suspension in the pulp and paper industry, especially for increasing the capacity of a screening department, a washing department, a thickening department, a press, a curved screen, or the like, includes the simultaneous separation and removal of the gases prior to the respective treatment stage.

Abstract: Unbleached pulp is combined with an aqueous alkaline solution while in a state of low consistency to distribute a first amount of alkaline material substantially uniformly throughout the pulp. The consistency of the pulp is then increased to above about 18%, and the high consistency alkali containing pulp is then treated with oxygen to effect delignification. The total amount of alkaline material applied to the pulp is between 0.8 and 7% by weight of oven dry pulp. High strength, low lignin pulps are subsequently formed which may be further bleached to high brightness with reduced amounts of chemicals.

Abstract: Paper pulp is produced from small chips (e.g. having a smallest dimension of between about 1 and 5 mm), which may be more easily penetrated by the treatment liquids resulting in a more uniform Kappa distribution which makes it possible to cook to lower Kappa numbers without losing strength. The chips are steamed and then impregnated with sulfur containing liquor in an impregnation vessel having a conveyor. The conveyor, such as an endless belt with baffles, moves the chips through the liquor rather than trying to circulate the liquor. From the impregnation vessel the chips move to the top of an upright digester where they are steamed, and then are subjected to digesting conditions, entrained in white liquor, in the digester and discharged from the bottom. The digester has smooth side walls, devoid of screens and circulation loops.

Abstract: A method of rinsing a slurry contained between a pair of converging mesh belts comprising the steps of splitting the slurry into two streams, each stream adjacent one of the converging mesh belts, introducing a stream of rinsing fluid between the two slurry streams, the point of introduction of the rinsing fluid between the two slurry streams is not more than 12 inches before and not more than 72 inches after the slurry streams contact the converging mesh, and creating compressive forces within the pair of mesh belts, which compressive forces continue for a distance of at least 24 inches after introduction of the stream of rinsing fluid.

Abstract: In a pressure diffuser, clogging of the tapered inlet passageway at the bottom of the vessel is minimized by providing a number of lubricating fluid introducing nipples disposed circumferentially around the annular passageway. The nipples introduce lubricating fluid so that it flows upwardly along the inner wall of the vessel. The vessel inner wall and the bottom support for the screen at the passageway are polished and free of projections, so that friction is minimized. The nipples are provided in sets that are staggered so that a nozzle is placed about every 15.degree. around the circumference of the vessel, and a common annular header--mounted on the support legs of the vessel--provides the lubricating fluid. Should screen movement slow as a result of paper pulp properties near the screen bottom support, the flow rate of lubricating liquid can be increased so as to significantly dilute the pulp at the passageway until slow movement of the screen is overcome.

Abstract: A method for thickening a liquid suspension of solid particles, such as papermaking pulp in water, uses a pair of spaced apart rolls and a woven wire or plastic wire belt trained around these rolls. The suspension is supplied at the first roll for centrifugal extraction and is carried by the belt to the second roll for further water extraction and thickening, and is then discharged from the apparatus. In one embodiment, the first roll is formed with an open surface, and the suspension is delivered to the web at least partially by flowing both into and out a roll chamber via the first roll openings, from a headbox in the on-running wedge zone.

Abstract: A process for delignifying and bleaching a lignocellulosic pulp without the use of elemental chlorine by partially delignifying the pulp to a K No. of about 10 or less and a viscosity of greater than about 13 cps; and further delignifying the partially delignified pulp with an effective amount of ozone for a sufficient time to obtain a substantially delignified pulp having a K No. of about 5 or less, a viscosity of greater than about 10, and a GE brightness of at least about 50%. The substantially delignified pulp may be brightened by the addition of a bleaching agent such as chlorine dioxide or a peroxide to obtain a final product having a GE brightness of at least about 65%, preferably above 70% to as high as 90%. Because of the absence of elemental chlorine in this sequence, filtrate from all stages but the chlorine dioxide stage ( if used) can be recovered without sewering. Major environmental improvements are thus achieved.

Abstract: A process for souring chemical or mechanical cellulosic pulp using carbon dioxide to obtain proper acidification of the pulp slurry. The souring is performed after a single or a multistage bleaching sequence ending with sodium hypochlorite, calcium hypochlorite or hydrogen peroxide or the like in a common process for the preparation of paper pulp. The use of CO.sub.2 permits bleaching to continue because CO.sub.2 does not destroy the bleaching residuals remaining from the single or last bleaching stages.

Abstract: Disclosed herein is a process for repulping or reclaiming fibers from latex-impregnated materials such as latex impregnated papers. The process involves treating the latex-impregnated material with an alkali solution for a sufficient period of time to separate the latex polymer from the fibers. This is followed by a washing step to rinse away the latex polymer thereby leaving the reclaimed fibers for subsequent use such as the formation of new paper stock.

Abstract: Disclosed is an improved chlorinated pulp bleaching process and apparatus which reduces caustic requirements significantly, wherein the washed chlorinated pulp, after first separating therefrom the effluent from the chlorination stage washing step, is treated with recycled alkaline extraction stage effluent in an additional washing step between the chlorination stage washing step and the extraction stage washing step; and wherein the effluent from the additional washing step is separated from the twice-washed pulp and, optionally wherein that effluent is recycled as shower water for the chlorination stage washing step, before the twice washed pulp is mixed with the caustic in the extraction stage.

Abstract: In a flat bed, Fourdrinier-type, countercurrent washer for pulp, the opportunities for the development of foam are minimized by "wet" operation of the washer so that the pulp mat remains essentially full of liquid as it passes from each washing zone to the next. Special provision is also made for compensating for drainage at too slow a rate in one washing zone by bypassing some of the flow of washing liquid to that zone so that it is delivered to the zone upstream therefrom. An additional feature is the provision of controls over the flow of drained liquid from one or more of the receptacles therefor so that any solid particles floating on the top of that liquid in the receptacle are delivered to the countercurrent flow which ultimately reaches the evaporator.

Abstract: In an atmospheric diffuser for the treatment of paper pulp (thickening, bleaching, and/or washing) the flow of backflushing liquid is controlled so as to maximize the effective treatment of the pulp. The pulp passes upwardly in a vessel. A number of annular screen assemblies are provided, with at least one screen associated with each screen assembly. The lower screen includes a barrier wall with a passage in the barrier wall adjacent the bottom end of the screen. Liquid which flows through the screen must flow to the passage in order to be withdrawn from the vessel, as the screen is slowly moved upwardly. When the screen is rapidly moved downwardly to cause backflushing, the backflushing liquid at the top end of the screen is liquid that recently passed through the screen at that point, so the pulp at that point--which is the cleanest along the length of the screen--has a minimal chance of being contaminated.

Abstract: The fibers of recycled paper are cleaned by agitating the slurry containing the fibers to maintain the fibers in suspension, and contacting the slurry with wash water to remove ink and other contaminants. The apparatus includes a passageway having screens forming opposite sides of the passageway. Agitators are within the passageway, and create enough turbulence to prevent fibers from settling or agglomerating. Channels adjacent to each screen carry wash water, and pump pressure creates a pressure differential across the screens to cause the wash water to contact the slurry and to be removed from the passageway.

Abstract: In a paper pulp treating vessel, such as a pulp thickener or diffuser, the screens are backflushed by reciprocating an internal piston utilizing an internally mounted hydraulic cylinder. The screens are supported by conduit arms having a central hub, and the hydraulic cylinder is mounted directly on top of the hub, with the backflushing cylinder mounted below the hub. Hydraulic lines lead from exteriorly of the vessel to the hydraulic cylinder within the vessel, and a sealing conduit is mounted surrounding the hydraulic lines. The sealing conduit extends to a point above the top of the vessel to act as an indicator if hydraulic fluid leaks in the vessel. A flexible bellows is connected between the sealing conduit and the hydraulic cylinder to allow tilting action between the arms and the top of the vessel.

Abstract: The invention concerns a method for the treatment of the spent liquors obtained from pulp production processes in the wood-processing industry, in which method the waste obtained from a chemical cooking process and that obtained from a mechanical process are merged for joint treatment. The chemical process may be e.g. a sulphate process and the mechanical process e.g. a chemi-thermomechanical process (CTMP), and the invention presupposes that the facilities for these processes are located close by each other, suitably within the same industrial complex. The essential feature of the invention is that the spent liquor of the CTMP is used as wash water in counter-current washing of the pulp obtained from the chemical process.

Abstract: A method of stabilizing pressure and flow conditions in a screening apparatus for treating a pulp is described, the pulp being supplied continuously to the screening apparatus through an inlet and passed through a pulp space along a screen of a screen body and discharged continuously through an outlet, said screen body being moved axially with a forward-going movement during an extraction phase and a backward-going movement during a backflushing phase. The flowrate of the pulp through, and the pressure conditions in, the treating zone of the screening apparatus are controlled by altering the volume at the inlet end and outlet end of the screening apparatus during the movement of the screen body.

Abstract: In a drum washer for washing the pulp for making paper to remove pulping liquors, the method and apparatus for providing the filtrate liquid being drained from the drum and pulp mat during a portion of the rotation cut-off which liquid can be continuously sampled and analyzed to give a more positive indication of washing efficiency.

Abstract: A method for washing pulp in a batch digester modified pulping process wherein black cooking liquor used for cooking the chips is partially displaced by pumping a first stage wash effluent into the bottom of the digester, additional amounts of the cooking liquor are displaced by pumping a second stage wash effluent, and so on, until sufficient increments of wash effluent have been pumped to displace the cooking liquor. A wash filtrate water is then pumped into the digester from a final pulp washing operation to displace the hot black liquor until all of the hot black liquor is sent to an accumulator, and the various wash effluents have been replenished in their respective stages.

Abstract: A method and apparatus provide for the effective centrifugal washing and/or thickening of paper pulp, using a perforated cylinder. A stock head box, located within the cylinder, applies a thin sheet of pulp on the interior the cylinder, at a high rate (e.g. about 20 meters per second), at a first arcuate position. The cylinder is rotated at high speed (e.g. 100 rpm, to provide an acceleration on the order of about 10 gs), whereby centrifugal force causes liquid in the pulp to move radially outwardly through the openings in the screen cylinder. The pulp is withdrawn from the interior of the cylinder by a vacuum roll or the like at a second arcuate position less than 360.degree. from the first position. The withdrawn pulp is moved by a screw conveyor or the like away from the cylinder in a dimension generally parallel to the axis of rotation, and the withdrawn liquid passes through channels in a drum surrounding the perforated cylinder, and is engaged by an impeller, and flows to a volute for removal.

Abstract: To remove disturbing wax particles and for increasing the specific volume the short fiber fraction is subjected to a thermal treatment, especially by application of water vapor or steam, in a heater, such as a worm heater throughout a defined residence time and a defined temperature. With relatively low energy expenditure the distrubing wax particles are eliminated in such a manner that no wax spots or speckles can be discerned in the finished product. The specific volume of the short fiber fraction is appreciably increased while obtaining a predetermined strength.

Abstract: In a pulp washing system where there is substantially constant average weight of pulp mat (on a dry pulp basis), washing uniformity is improved by controlling the weight per unit area of liquid alone or liquid and pulp combined in the pulp mat across its width to obtain a substantially constant distribution of selected property in the pulp mat across its width. This is accomplished by steps comprising determining the property in a plurality of selected locations across the width of the pulp mat and also the average value of the property across the width and controlling dilution liquid input into the headbox in response to the determination to produce of substantially constant distribution of the property across the width of the mat.

Abstract: It is desirable to be able to treat medium consistency (e.g. about 8-12% by weight) paper pulp suspensions with treatment liquid (e.g. a wash liquid), and to thicken the pulp to about 30-50% consistency at the same time. A moving (e.g. rotating) channel is defined by a root wall and upstanding side walls--some or all of which are perforated--and treatment liquid is introduced by an arcuately elongated distributor with perforated side walls into the center of the pulp within the channel, filtrate flowing out through the perforated walls. A pivoted wall portion of the stationary housing of the treatment device restricts outflow of the thickened pulp cake from the device, the cake flowing between a doctor blade and the pivoted wall portion.

Abstract: In the method for the manufacture of a paper pulp for currency use from a stock comprising textile fibers, the operations of boiling, bleaching, chopping, breaking, cutting and washing of the textile fibers are performed in at least one treatment machine (10, 40) of the type having two co-rotating screws, in a plurality of phases taking place successively and continuously. The operations include a phase of feeding and mixing the stock with water, at least oen compression phase, at least one phase of shearing of the textile fibers, at least one phase of treatment of introduction of boiling and bleaching reagents, at least one phase of washing of the bleached pulp by introduction of washing water, and a phase of transferring and evacuating the bleached and washed pulp.

Abstract: A method and system for cooling pulp discharged from a batch type digester and recovering heat from it. A stream of pulp together with spent cooking liquor is discharged from a batch digester to a diffuser and passed through the diffuser at substantially the same pressure as that of the digester. The pulp stream is caused to flow between screens and hot spent cooking liquor is displaced with cooler liquor flowing across the pulp stream thereby lowering the temperature of the pulp stream. The displayed cooking liquor and the pulp is withdrawn from the diffuser.

Abstract: The present invention relates to a method of intensifying the washing of a fiber suspension. In particular, the present invention relates to decreasing the lignin content of a fiber suspension by extracting. Lignin removal is usually carried out at a consistency of less than 3% whereby heating consumes much energy. The method of the invention allows a considerable increase in the consistency of the suspension which results in that the energy consumption is decreased to a fraction of the one required by prior art methods. A characteristic feature of the method of the invention is that dry substance and chemicals contained in the fibers are extracted at a raised pressure and temperature.

Abstract: The chemical components of lignocellulosic material which have been dissociated by a steam explosion process can be extracted from the mixture of components using a solvent extraction process. The solvents are water, alcohol and a mild caustic in that order, or the alcohol step can be by-passed and only water and caustic are used. The caustic is a stronger solvent and it will extract the alcohol solubles along with the caustic only solubles. The eluant from the these extractions contains a range of lignin derived substances, which have different applications, such as thermoplastic and thermosetting characteristics. This invention describes a method for partitioning these lignin components into reproducible fractions having definable characteristics for particular applications. For instance, many copolymer applications require a thermosetting only fraction of the lignin. Other applications require a thermoplastic only lignin.

Abstract: An improved process for delignifying and bleaching nonwoody, lignocellulosic material into products digestible by ruminants and ingestible by humans. The process comprises treating the substrate in an alkaline solution for a period of time, separating the wetted substrate from the slurry and then treating the wetted substrate with an alkaline peroxide solution at an initial pH of 8.5 to 11.0 for a period of time, and separating, washing and drying the product.

Abstract: In the method of chemical pulping of wood including a chlorination stage pulp bleaching step followed by alkaline extraction, a method of reducing the amount of dioxins and furans produced thereby is disclosed wherein the brownstock pulp is first washed with alcohol prior to bleaching.

Abstract: Method for transferring fibrous materials transportable with a liquid between various treatment stages, preferably from digesting (10-16) to a subsequent treatment (38) by means of circuits of circulating liquid. Material from one or several discontinuous treatment steps (10-16) are supplied to a subsequent continuous treatment step the material being fed into the continuous step (38) by displacement by means of a liquid portion (36) withdrawn from the said step.

Abstract: This invention is an improved liquid distribution device and more particulary an elongated shower pipe which uses a reinforced, enclosed, curved vane and a plurality of uniquely designed spray outlets to evenly dispense a controlled, continuous thin sheet of liquid spray, having a substantially equal rate of application, velocity, pressure, consistency, and thickness, across a width of a rotary drum, the spray having a uniform, somewhat staggered and overlapping spray pattern. The enclosed curved vane significantly resists breakage when impacted against a pulp buildup and prevents debris from disrupting the spray pattern.

Abstract: An apparatus for treating, e.g., washing or filtering, fiber suspensions having a consistency of 8-20%, the apparatus including at least on rotatable filtering surface, an arrangement for feeding the suspension to a treatment region of the apparatus, and an arrangement for discharging the suspension from the treatment region, the feeding arrangement including at least one pressure chamber for fluidizing the suspension, at least one inlet duct for introducing the suspension to the chamber, and at least one feed duct for transferring the suspension from the pressure chamber to the treatment region.

Abstract: The viscosity of paper pulp is maximized, while chlorine bleaching is minimized or eliminated, by subjecting the pulp suspension to multiple consecutive oxygen bleaching stages, with a countercurrent wash between O.sub.2 stages. A chelating agent--such as EDTA--may be added to the countercurrent wash liquid, and/or another chelating agent--such as DTPA--may be used to pretreat the pulp.

Abstract: Method and apparatus for reducing contamination in processed pulp and in white water effluent discharged from a pulp dryer or paper making mill. The system includes multiple pulp bleaching and washing stages wherein white water effluent discharge from the dryer or paper making mill is fed to the next-to-last washing stage and fresh water is supplied to the last washing stage.

Abstract: An elongated, imperforate housing (2) has a slurry inlet port (5) at one end and a pulp discharge port (6) at the other end. A pressing section (2b) within the housing is in direct fluid communication with the inlet port, and extracts liquid from the slurry by passing the slurry through a first compression restriction (108) to produce a pressed pulp. An annular washing section (2c) within the housing is positioned immediately downstream of, and in direct fluid communication with, the first compression restriction. The washing section has radially inner (109) and outer (14) cylindrical walls defining an annular washing chamber (110) for decompressing, diluting, and washing the pressed pulp. The washing is accomplished by injecting a washing liquid into the washing chamber through the inner wall, and simultaneously through the outer wall while the mixture is agitated. A repressing section (2d) within the housing is in direct fluid communication with the washing section, for receiving the conveyed mixture.

Abstract: A pressure diffuser includes in a liquid-tight pressurized vessel a vertical screen and which screen and vessel wall define first and second interior volumes for transmitting pulp from a pulp inlet to a pulp outlet and receiving displacement (e.g. wash or bleach) liquid transmitted from headers through the pulp. The screen ends have different cross-sectional areas, and quick movement of the screen effects backflushing. The volumes are segregated by a vertical, generally cylindrical, screen. A chamber is provided in communication on opposite sides of a piston therein with the pulp adjacent the pulp inlet and the extracted liquid. By displacing the piston immediately prior to rapidly moving the screen vertically to effect backflushing through the screen, the pulp pressure on the screen is being reduced and at the same time a volume is made available adjacent the pulp inlet in the chamber thus avoiding pressure shocks and compaction of the pulp adjacent the inlet caused by the movement of the screen.

Abstract: A retainer maintains a body of standing washing liquid against the outside surface of a mat, such as a pulp mat. The mat moves on a vacuum screen which draws washing liquid from the body of liquid through the mat to clean it. The retainer pivots to adjust different mat heights and allows clumps of material on the mat to pass underneath the retainer. Clumps on the mat are also smoothed into the mat as the clumps pass underneath the retainer.

Abstract: The chemical components of lignocellulosic material that have been dissociated by a stream explosion process can be extracted from the mixture of components using a solvent extraction process. The dissociated lignocellulosic material is put in a column and the substances which are soluble in water, alcohol and caustic are leached out of the mixture by solvent extraction with relatively small volumes of those solvents. No agitation is used. Substantially pure cellulose remains in the column and it can be bleached before removal from the column.

Abstract: Apparatus for treating a pulp suspension with a treatment liquid is disclosed, comprising a continuous pervious belt for receiving the pulp suspension and moving it through a treatment zone in a predetermined direction. A treatment liquid supply is located above the continuous belt for supplying the treatment liquid onto the pulp suspension as it travels through the treatment zone, and a collector is located below the continuous belt for receiving liquid passing through the pulp suspension.

Abstract: A method of delignification of cellulosic fiber material is described. The pulp containing said cellulosic fiber material is fed in a main line containing a main reactor in which the pulp is treated with oxygen. The pulp is screened at at lest one point in the main line, and the screen reject obtained is fed in a branch line containing at least one secondary reactor for separate treatment with oxygen. According to the invention the separate treatment with oxygen is carried out without previous refining, and the screen reject thus separately treated in said branch line is returned to the main line at a point upstream of said main reactor.

Abstract: An apparatus for treating fibre material containing liquid, comprising two rotating drums (2, 3), an endless driven belt (17) pervious to liquid and gas and extending between and passing around the surfaces (8, 9) of the drums, a feeding device (10) for the supply and a discharging device (13) for the removal of the fibre material, at least one container for collecting liquid, the liquid being displaced from the fibre material through the endless driven belt (17), a continuous wall (18) impervious to liquid and gas and extending along a main part of and at a distance from the belt (17) from the feeding device (10) to the discharging device (13) in such a manenr that a continuous space (19) is defined for the fibre material between said wall (18) and the belt (17), and at least a part of the space (19), seen in the direction of movement of the belt (17), forms one or more treating zones where liquid is displaced from the fibre web through the movable belt (17) to one or more containers.

Abstract: The screens of a pulp treating vessel, such as a paper pulp thickener, or diffuser, are back flushed in a simple yet effective manner. The screens are mounted to a supporting conduit within a vertical vessel, and a cylinder is connected at one open end to the conduit, and the other open end is disposed within the pulp inside the vessel. A piston is mounted within the cylinder and relative movement between the piston and cylinder is effected periodically in order to force liquid from within the cylinder into the conduit and out the screens, backflushing the screens and preventing clogging. Since no additional volume of liquid is added to the vessel during backflushing, no surge occurs in the vessel. Conventional accumulators, on/off valves, and the like can be eliminated while--in the case of diffusion washing--efficiency can be increased as much as 20-30% and capacity increased as much as about 15%.

Abstract: The invention relates to an apparatus or plant or arrangement for the treatment of a dilute suspension of fibers or layer of material passed between two endless foraminous belts or wires or the like conveying means, the forming fibrous board being made to pass between the foraminous belts along at least one container for a treatment medium and at least some of the treatment containers being provided with a wall having orifices on the side facing the fibrous board for generating a pressure difference on the same, but being otherwise closed against the environment, and/or at least some of the treatment containers closed against the environment having walls closed against the foraminous belts and thus against the fibrous board, but otherwise open towards the foraminous belts. According to the invention, a reduction of the energy requirement in the displacement washing of filter cakes is sought above all.

Abstract: Wash water input into a pulp washing system is controlled in response to measurements on a stream of output constituents of reduced transverse dimension compared to the transverse dimension of the washed pulp mat discharge stream from the pulp washing system. The measurements are conducted simultaneously across the entire width of the reduced dimension stream on all the washed pulp and water leaving the pulp washing system. The measurements are readily carried out using apparatus including means below said reduced dimension stream.

Abstract: An improved process of purifying the product from an alkaline peroxide treatment process for delignifying and bleaching nonwoody lignocellulosic agricultural residues comprising, optionally washing with water, then lowering and maintaining the pH of the substrate at less than about pH 3.0, then washing sufficiently to remove residual chemicals, separating the product from the wash liquid and, optionally, drying the product.

Abstract: A pressure diffuser for paper pulp includes a vertical pressurizable liquid-tight vessel having a pulp inlet at the bottom and a pulp outlet at the top. One or more ring shaped screen elements providing first and second concentric screen surfaces, are vertically mounted within the vessel. A number of radially extending header arms mount the screen elements for movement in the vessel and in fluid communication with it. A first linear actuator effects reciprocation of the arms. A cylinder, open at both ends, is affixed to the arms and extends both above and below them, and a piston is disposed within the cylinder, below the arms. A second linear actuator is operatively connected to the piston to effect reciprocation of the piston in the cylinder. A guiding conduit surrounds the open end of the cylinder above the arms and guides reciprocation of the cylinder and transports liquid from the arms to an effluent outlet.

Abstract: Pulp washing efficiency at any given dilution factor and production rate is maximized by controlling washing surface speed in response to determination of total mass of product stream in weight per unit area on the surface and simultaneously controlling the rate of dilution liquid introduction in response to sensing of feed level in the container feeding the surface, thereby to obtain a substantially constant level of pulp in the feed and in the pulp mat formed on the washing surface which is to undergo washing and a substantially constant weight of pulp mat (on a dry pulp basis) per unit area on the washing surface.

Abstract: An air-tight vat under pressure completely encloses a rotatable drum. The vat is constructed so that it may be completely submerged in liquid. The vat has a liquid filled take-off chamber. The pulp is fed to the vat through a pulp inlet. The pulp is formed and compacted to form a pulp mat. Directly following the forming and compacting of the pulp is a washing zone for washing the pulp mat. After washing the pulp mat is again compacted. The pulp mat is removed from the drum at a removal point located in the liquid filled take-off chamber, thus providing a pulp suspension in the take-off chamber. The suspension is removed from the vat through a pulp outlet extending from the liquid filled take-off chamber.