Abstract: The present invention relates to the thickening of pulp suspensions. A low consistency pulp suspension is fed to a pre-thickener (10) through an inlet conduit (18). A layer of thickened pulp, formed on a filter surface (22), is pushed along the filter surface by a cleaning member to the discharge end of the pre-thickener and is discharged through the outlet (20). The cleaning member comprises a rotating shaft (30), on which shaft at least one screw thread (32) is fixed so as to leave a free space between the shaft and the screw thread. Essentially non-thickened pulp is allowed to flow through the apparatus via this space.

Abstract: This invention relates to an improved process for manufacturing bleached thermomechanical aspen pulp having reduced yellow after treatment with aluminum based chemicals such as alum which are used in paper making processes. In this improved process the pulp is washed prior to, after or between the bleaching stages or a combination of the foregoing.

Abstract: Fibrous organic biomass is converted into pulp in a flow-type process which uses pretreatment of the biomass, specific selection of acid and alkali agents and a low concentration of fiber to liquor.

Abstract: A pulp product that has a low COD is comprised of an unbleached pulp that is soaked and washed in alkaline water for a sufficient time so that the COD after soaking and washing is less than or equal to 3.0 kg/1000 kg of dry pulp. The pulp is produced by repetitively soaking and washing an unbleached pulp in alkaline water that is never allowed to drop below pH 7.0. The pulp is soaked and washed for a total of at least 400 minutes at an elevated temperature to produce the pulp product that has a low COD.

Abstract: Process for preparing dry broke in one of a paper, cardboard or coating machine. The process includes diluting the dry broke to a consistency of between about 15 to 60%, and slushing the dry broke with shear forces sufficient to crush filler particles in the dry broke.

Abstract: A process is provided for preparing a commercially acceptable pharmaceutical grade microcrystalline cellulose which comprises: a) repulping a pulp, the pulp having a composition, b) pressing the pulp obtained in a; c) decompacting of the pulp obtained in b; d) feeding the pulp obtained in c) into a pre-heated reactor; e) cooking the pulp in the reactor until the pulp obtains a desired degree of polymerization, said cooking being performed at a temperature, a time, and a pressure which is a function of the desired degree of polymerization and the composition of the pulp, the cooked pulp being hydrolyzed cellulose; f) partially depressurizing the reactor; g) injecting water into the reactor; h) discharging the hydrolyzed cellulose from the reactor, i) filtrating the hydrolyzed cellulose; j) deaggregating the hydrolyzed cellulose of step i; and k) drying the hydrolyzed cellulose to form microcrystalline cellulose.

Abstract: Free flowing particles useful in absorbent articles are disclosed, including fibrous nits and methods of preparing fibrous nits. In one embodiment, fibrous nits are prepared from disperging cellulosic fibers in the presence of a nit conditioner which modifies nit particle size and properties for improved performance of the particles. In other embodiments, nits are prepared in multiple disperging steps or by disperging fibers under two or more conditions.

Abstract: Process and decker for bringing together a first aqueous pulp suspension layer with at least one additional suspension layer. The process includes moving the first pulp suspension layer and the at least one additional suspension layer on moving layer supports, and guiding sides of the first pulp suspension layer and the at least one additional suspension layer that are adapted to contact each other on guiding surfaces that are one of stationary and limitedly moving. The guide surfaces include contoured surfaces arranged to run substantially parallel to the layer supports. The process further includes applying the at least one additional suspension layer onto the first pulp suspension layer at a wedge-shaped gap, and draining the first pulp suspension layer and the at least one additional suspension layer. The decker includes at least one rotating cylinder, and an endless wire guided around at least a portion of an outer circumference of the at least one rotating cylinder.

Abstract: Methods and corresponding devices are set forth for the continuous mechanical dewatering of aqueous suspensions or elutriations, particularly of waste-paper suspensions or slurries, between an endless mesh band and an endless compression surface having a closed, smooth surface and running in the direction of operation. The suspension cake to be dewatered is compressed between the mesh band and the compression surface. The requisite pressure is achieved by wrapping the mesh band around the cylindrical compression surface under longitudinal tension, whereby the expelled water is removed from the suspension cake by means of the mesh band. Devices are provided which both increase the operational duration of the dewatering pressure of the existing mesh band on the suspension cake, and at the same time increase the pressure substantially, without obstructing the runoff of the pressed-out water. The method of the invention increases the compression pressure from about 1 bar (heretofore) to a pressure of, e.g.

Abstract: A pulper in a stock preparation system includes a housing with a fiber inlet, at least one water inlet, at least one outlet and an inner chamber. A plurality of rotatable augers extend into the inner chamber.

Abstract: The object of the present invention is a method for making mechanical pulp, such as thermomechanical or chemi-thermomechanical stock. The mechanical pulp is used as a raw material for printing paper, and its freeness value is 30-70 ml CSF. The stock refined by the method is screened in several stages to form accept and reject stock portions. The wood raw material is refined at the first stage of refining at a superatmospheric pressure of over 400 kPa to form a stock that has a freeness value of 250-700 ml CSF.

Abstract: The distributor device is for cellulose pulp of low and medium consistency and is used to form a uniform pulp web running from the distributor device in an apparatus treating the cellulose pulp. The distributor device has a cylindrical distributor housing arranged horizontally and transverse to the pulp web, and an inlet for the cellulose pulp at one end of the distributor housing and on the pulp web side. Pulp is fed with feed screws from the inlet and along the length of the distributor housing. The web is initially formed via the outlets defined along a generatrix in the jacket surface of the distributor housing. An optimum distribution of low-concentration pulp is obtained with the holes arranged along the generatrix in the jacket surface of the distributor housing. The holes have a defined hole diameter (D) and are arranged at a distance (X) from each other. The interaction with the feed screw makes it possible to keep the holes free from clogging.

Abstract: A feed system for a cellulose pulp treating vessel (such as a continuous digester) is not limited by the required L/W ratio of the pump feeding a wood chip slurry to a high pressure transfer device, the feed system may be kept at a low temperature to minimize flashing of liquid into steam, and a return conduit from the treatment vessel to the transfer device high pressure inlet may be eliminated. Some of the liquid is removed from the slurry just before the low pressure inlet to the transfer device, and/or just after the high pressure outlet, to reduce the L/W ratio of the slurry by at least 0.25, e.g. from 3.0:1 to 2.25:1 just before the low pressure inlet, and from, 7.0:1 to 5.0:1 substantially immediately after the high pressure outlet.

Abstract: A process and apparatus for the preparation of improved cellulose pulps is provided, in which defibered pulp is screened for removal of shives, and fibers with low bonding ability are removed in hydrocyclones, and rejects from the hydrocyclones are treated in refiner. In the process a specific combination of characteristics for the hydrocyclones and the volumetric flow is used in order to prepare pulps which give products of improved qualities, such as higher tensile strength, tear strength, light-scattering, surface smoothness, and specially low shive content.

Abstract: A method of manufacturing high purity fiber cement grades of cellulose fibers is described. Additional washing steps, coupled with an elevated temperature, are used in the process to extensively wash the pulps and remove substantially all COD components remaining in the pulps. The pulps are counter-currently washed by diffusion and dewatering at elevated temperatures following the brown stock washer systems. During the additional washing steps, the pulps are soaked in counter-current heated water for a pre-determined time and some chemicals may be introduced to chemically break down the COD components in the pulps and to make them more soluble in the aqueous solution. The additional washing steps can be performed using existing equipment at conventional pulp mills. A formulation and a process of making fiber reinforced cement composite materials are also described using the low COD and high purity cellulose fibers.

Abstract: A feed system for a cellulose pulp treating vessel (such as a continuous digester) is not limited by the required L/W ratio of the pump feeding a wood chip slurry to a high pressure transfer device, the feed system may be kept at a low temperature to minimize flashing of liquid into steam, and a return conduit from the treatment vessel to the transfer device high pressure inlet may be eliminated. Some of the liquid is removed from the slurry just before the low pressure inlet to the transfer device, and/or just after the high pressure outlet, to reduce the L/W ratio of the slurry by at least 0.25, e.g. from 3.0:1 to 2.25:1 just before the low pressure inlet, and from 7.0:1 to 5.0:1 substantially immediately after the high pressure outlet.

Abstract: Process for increasing the water retaining ability of fibrous paper stocks. The process includes knead dispersing a fibrous paper stock having a stock concentration of at least about 20% and a temperature greater than about 45° C. A treatment for the knead dispersing is at least about 10 seconds. The process further includes completing a post-treatment phase to a machine tub of a paper machine in a reaction time of no longer than about 30 minutes.

Abstract: A method of treating wood-fiber pump, particularly wood-fiber pulp that contains recycled paper, comprises delivering the pulp to and advancing the pulp in a heating zone while delivering steam to the heating zone. The pulp is finely-divided in a disperser and the finely-divided pulp delivered to a screw press without separate departure of steam, so as to compact the pulp in the end of the screw press and therewith form a plug seal. At the same time, one or more bleaching chemicals is or are supplied during one or more treatment stages, and the temperature of the pulp is regulated to obtain an optimal bleaching process or optimal bleaching processes. The temperature of the pulp can be raised or lowered by supplying steam or water thereto respectively. The invention also relates to a plant for carrying out the method.

Abstract: A method of making fiber bundles and fibrous structures. The efficacy of a fiber bundle in handling complex fluids may be improved by subjecting an aqueous suspension of fibers at high consistency to elevated energy input with sufficient working of the fibers. The fibrous structures prepared according to the methods herein include at least one fiber bundle and at least one debonding agent. The fiber bundle includes at least one particulate material consisting essentially of entangled fibers.

Abstract: Process for dissolving used paper including adjusting a content of solid particles of used paper to a range between about 15 and 35%, kneading the used paper with a specific work of at least about 10 kWh/t, diluting the kneaded used paper to a content of solid particles below about 6%, separating non-fibrous contaminants with wet screening, adjusting a solid material content to less than about 3%, and separating heavy particles with at least one hydrocyclone.

Abstract: Processes are disclosed for extracting sugar rich liquor from sugar cane. The sugar cane is first treated by pulping it in two tub type pulpers having a rotating impeller. The contents of the first pulper are extracted through the bedplate of the extractor and are forwarded onto the second pulper. The contents of the second pulper are extracted through the bedplate of the extractor and are forwarded to form a mat on a moving belt countercurrent extractor of the type having a foraminous belt. Negative pressure is applied below the belt to assist the extraction of a sugar rich liquid component through the belt. The material passes through several separation zones as it travels on the belt with liquid applied to the mat from a region above the belt. The extracted liquid component is collected for further processing.

Abstract: A method and an apparatus for heating or cooling material having poor thermal conductivity, especially medium-consistency fiber suspensions. The material is directed, substantially as a plug flow, at a velocity below 5 m/s (e.g. 0.1-1 m/s) through an apparatus formed by a flow channel provided with heat exchange surfaces. The flow of the material is throttled at a throttling point by a more than 30% reduction in the cross-sectional area of the channel. After throttling, the material is discharged from the throttling point in such a manner that another portion of the material contacts the heat exchange surfaces.

Abstract: A process for production of chemical fibrous pulp for making paper, paperboard and other fibrous products from herbaceous plants, such as kenaf. Pulp from the herbaceous plant is made by a process which involves densification of pieces of all or part of the plants; i.e., both the core and the stalk or just the core portion, into cubes or pellets having a density ranging from about 15 to about 70 lbs/ft3, preferably from about 25 to about 50 lbs/ft3, which are then chemically digested to produce a fibrous pulp. The densified cubes or pellets may be digested alone or together with conventional wood chips. A principal advantage of the invention is that the densified cubes or pellets exhibit significantly better yield and strength after treatment by conventional chemical pulping methods as compared with the undensified material, enabling more efficient and economical use of this material to supplement limited supplies of conventional hardwood and softwood pulp sources.

Abstract: A system and method for feeding a slurry of comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester also treat the material to remove metals before digestion. During pumping of the slurry with at least first and second series connected pumps, at or upstream of at least one of the pumps chemicals (acids and/or chelating agents) which dissolve the metals in the material are added, and preferably some of the liquid is removed so as to purge at least about 10% (e.g. about 20-80%) of the metals in the material. The metal removal preferably takes place substantially immediately before alkaline digestion.

Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using one or more slurry pumps located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge. A return line from the top of the digester may, but need not necessarily, be operatively connected to the one or more pumps and if connected to the pumps, the liquid in the return line may be cooled to a temperature at which it will not flash during handling. Recirculation loops may be established associated with one or all of the slurry pumps to facilitate startup.

Abstract: Process and apparatus for dispersing fibrous paper stock that includes delivering an aqueous fibrous paper stock, pressing some water out of the aqueous fibrous paper stock to form a highly consistent coarse fibrous paper stock, and introducing the highly consistent coarse fibrous stock into an effective area of a mallet roll having circulating mallets which cooperate with fixed peripheral impact sections. In this manner, the highly consistent coarse fibrous stock is loosened and distributed. The process also includes transporting the highly consistent fibrous paper stock into a dispersing machine, and dispersing the highly consistent fibrous paper stock in a dispersing machine.

Abstract: The present invention relates to a method for recycling of old corrugated container (OCC) using flotation and kneading treatment and more particularly, to a method for recycling of OCC, wherein OCC is treated withflotation and kneading, treatment, and thereby removing fines and ink spot in the waste pulp and improving the strength and drainage property. As a result, it can be recycled similar to the expensive virgin unbleached kraft pulp.

Abstract: Process for increasing the water retaining ability of fibrous paper stocks. The process includes knead dispersing a fibrous paper stock having a stock concentration of at least about 20% and a temperature greater than about 45° C. A treatment for the knead dispersing is at least about 10 seconds. The process further includes completing a post-treatment phase to a machine tub of a paper machine in a reaction time of no longer than about 30 minutes.

Abstract: Methods for the concentration of a dilute material such as a fiber suspension are disclosed including enclosing the dilute material between a first straining belt and a second straining belt both moving through endless paths, and in which the width of the first straining belt is greater than the width of the second straining belt, and the method includes causing the longitudinal edges of the first straining belt to overlap the longitudinal edges of the second straining belt in an initial concentration stage, unfolding the longitudinal edges of the first straining belt and then further compressing the concentrated layer produced against the first straining belt in a further concentration stage. Apparatus for carrying out this method is also disclosed.

Abstract: Process and device for the mixing of suspensions with possibly different natures and/or compositions in the stable section of a paper machine. In the process, a suspension, particularly of the backwater of the paper machine, is piped in a mixing tube with the main flow direction in the longitudinal direction of the tube, and additional suspensions, with possibly different solid content, are injected. In the device, a mixing device and piping carry the suspension in the stable section of a paper or cardboard machine and blend suspensions with a higher solid content into a first suspension with little or no solid content. The mixing device and piping include a tube, at least one inlet for the first suspension, a plurality of feeds for the higher solid content suspensions to be admixed, and one outlet for the blended suspension, with a new solid content, arranged downstream from a bend in the tube.

Abstract: A device for impregnation of webs of porous materials with a liquid impregnating medium under increased pressure comprises a roller rotatable about a horizontal axis, a trough arranged so that the roller is partially inserted in the trough to form a chamber between an inner surface of the trough and an outer surface of the roller, a unit for supplying an impregnating medium into the chamber, and a unit forming an inlet slot for introducing a web to be impregnated into the chamber and an outlet slot for withdrawing the impregnated web from the chamber. The chamber over a path from the inlet slot to the outlet slot narrows and again increases many times.

Abstract: A process for draining a fibrous pulp web is preferably carried out on drum thickeners or disk filters. A suspension to be drained rests against a perforated first face, which is a part of the rotor of the drum thickener or disk filter, is transported from the suspension vat, and then arrives in a thickening region. The thickening region contains a second face, wherein the first and second face have a relative speed in relation to each other. The effectiveness of the thickening can be significantly increased by vacuum zones provided on the drum thickener or disk filter.

Abstract: A method of displacement washing of cellulose pulp achieves substantially optimal results without the consumption of excessive clean wash liquid. In the practice of the method there is at least one washing stage, and a second stage, including a suction, press, and/or thickening stage, following the washing stage. Cellulose pulp is fed to the washing stage, and then the washed pulp is fed to the second stage. A first filtrate is withdrawn from the second stage and a second filtrate is withdrawn from a washing stage of the at least one washing stage, or the second stage. The first filtrate is directed to the washing stage and the first filtrate is used as washing liquid in the washing stage. For example the washing stage may include a last washing stage in a multi-stage fractionating washer, and the second stage may be in the fractionating washer; and the first filtrate may be directed to the last washing stage of the multi-stage fractionating washer.

Abstract: A method and device for drainage of a fibrous suspension where a converging drainage gap is formed between a first area and a second area. At least one of the first area or the second area is water permeable. A curved drainage zone is connected to the converging drainage gap. The first area moves relative to the second area. A fibrous suspension is introduced into the converging drainage gap. The fibrous suspension is transported by one of the first area and the second area as a layer. The first area and the second area are compressed closer together thereby causing drainage from the fibrous suspension through one of the first area or the second area.

Abstract: The present invention relates to a method for treating a pulp suspension in which the suspension is rotated in a rotationally symmetrical, rapidly rotating and permeable screen basket so that the suspension is subjected to the influence of a centrifugal force and dewatered at the same time as the suspension is conveyed by a rotating screw along the inner wall of the screen basket. The invention is characterized in that the suspension is caused to rotate by means which are arranged at the entrance to the screen basket, and in that the outer edges of the said screw bear against or are immediately adjacent to the screen basket and rotate at a higher speed than does the screen basket so that the screw scrapes the inner wall of the screen basket.

Abstract: A process for conditioning an ozone gas recycle stream in an ozone pulp bleaching process, wherein the level of carbon dioxide in the recycle stream is controlled to allow full capacity operation of the ozone generator. Carbon dioxide concentration is identified over the relevant operational ranges and maximum concentration is identified for full capacity/optimum efficiency operation. Specific methods are described for controlling carbon dioxide concentration including purging a portion of the recycle stream, counter-current scrubbing of the recycle stream with an alkaline solution and passing the recycle stream through an adsorbent material. Contaminants entering the system also may be reduced by directing the purged recycle stream, which is relatively oxygen rich, into the dewatering press where pulp consistency is increased. In this manner nitrogen surrounding the pulp is displaced by oxygen and thus, does not enter the bleaching/ozone system with the pulp.

Abstract: The invention realizes an improved mechanical strainer for fibrous suspensions including: a rotor; a filtering basket substantially coaxial externally to said rotor; an interspace defined between the side surfaces of said rotor and of said filtering basket; an outer casing suitable to house said filtering basket and said rotor. Inside this outer casing there are: a feeding chamber receiving the fibrous suspension to be treated, a delivery chamber of the "accepted" and a waste chamber of the "waste". The rotor is provided with a plurality of diffusing ducts developing through diverging ways according to the flow direction and being suitable to pipe the fibrous suspensions to be treated from said feeding chamber to said interspace.

Abstract: A process for thickening a fibrous pulp suspension by guiding the suspension between a rigid first face and a flexible second face that move in relation to each other and form a converging draining gap, where the first face and/or the second face is/are water permeable, and where the process includes providing the suspension to be drained, forming from the suspension a fibrous pulp layer with a solid matter content of at least about 4% on at least one of the first face and the second face, guiding the fibrous pulp layer into the draining gap, applying a pressure differential in the draining gap via the second face to thicken the fibrous pulp layer, the pressure differential being formed by stretching the second face and pressing the first face and the second face toward each other to drain water from the fibrous pulp layer, and transporting the thickened fibrous pulp from the draining gap.

Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using one or more slurry pumps located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge. A return line from the top of the digester may, but need not necessarily, be operatively connected to the one or more pumps and if connected to the pumps the pressure in the return line may be reduced utilizing a pressure reduction valve and/or a flash tank.

Abstract: The present invention relates to a method for treating a pulp suspension in which the suspension is rotated in a rotationally symmetrical, rapidly rotating and permeable screen basket so that the suspension is subjected to the influence of a centrifugal force and dewatered at the same time as the suspension is conveyed by a rotating screw along the inner wall of the screen basket. The invention is characterized in that the suspension is caused to rotate by means which are arranged at the entrance to the screen basket, and in that the outer edges of the said screw bear against or are immediately adjacent to the screen basket and rotate at a higher speed than does the screen basket so that the screw scrapes the inner wall of the screen basket.

Abstract: Process and device for draining a fibrous pulp suspension. The process may include positioning two surfaces to converge in a downstream direction, feeding the fibrous pulp suspension between the two converging surfaces, driving at least one of the two converging surfaces to move the suspension with a relative translational velocity, and draining the fibrous pulp suspension through each of the two surfaces. The device may include two arcuate surfaces positioned to form converging surfaces. One of the two arcuate surfaces may include a drivable, pivotable, and rotatable cylinder having an outer sleeve with openings, the other of the two arcuate surfaces may include a screen positioned to be guided around at least a portion of the outer sleeve. The screen and the openings may form drains for draining the fluid pulp suspension.

Abstract: A device to drain a fibrous pulp suspension including an arched surface that is impermeable. The arched surface, moreover, is surrounded by a permeable belt. The belt and the arched surface are able to be moved such that there exists a relative velocity between the belt and the arched surface. The arched surface includes recesses that are able to take up quantities of fluid.

Abstract: A method for producing extensible paper, comprising the following stages:feeding a mix of vegetable fibres to a kneader member,mixing the mix with water in the kneader,beating the fibres to obtain a pulp,transferring the beaten pulp into a flow chest,feeding the beaten pulp from the flow chest onto a paper web formation cloth with consequent reduction of the water percentage by gravity and vacuum,pressing the web, with consequent further reduction of its water content,initial drying of the paper web to a substantially constant moisture content of between 15% and 65%,compacting,final drying to a moisture content of between 15% and 4%, preferably 10%-8%,glazing,wherein:the beating stage is carried out by rubbing the fibres in a multistage unit to obtain a pulp having a degree of beating of at least 30.degree.

Abstract: A method of bleaching secondary fibers. A secondary fiber pulp is first slushed and then transferred at a consistency of 20-40% to a disperser. In the disperser, the secondary fiber pulp is mechanically treated and mixed so that ink particles in the secondary fiber pulp are dispersed throughout the secondary fiber pulp. While the secondary fiber pulp is being treated and mixed in the disperser, oxygen is delivered to the disperser so as to distribute the oxygen within the secondary fiber pulp.

Abstract: A method for concentrating a suspension comprises the steps of providing a first surface; providing a second surface; introducing a suspension; moving the second surface relative to the first surface; and applying suction to the second surface. The first surface is relatively liquid-tight and includes a feature for increasing friction. The second surface is relatively liquid-pervious, faces the first surface, and is moveable relative to the first surface. Introduction of the suspension between the first and second surfaces forms a suspension web. Moving the second surface relative to the first surface and applying suction through the second surface causes dewatering of the suspension web and increased friction between the suspension web and the second surface.

Abstract: A process for increasing a degree of whiteness of paper pulp may include bring paper fiber pulp, which may at least partially include printed waste paper, into a suspension with water. The suspension may be mixed with bleaching aids and bleaching chemicals. The bleaching chemicals may preferably contain molecular oxygen. Intensely mechanically treating the pulp, e.g., at at least 20 kWh/to, prior to bleaching the pulp suspension. The bleaching period may take at least 10 minutes, with a pressure above the atmospheric pressure being exerted during the bleaching. After bleaching, a major portion of remaining color print particles may be removed from the bleached pulp.

Abstract: Apparatus for liquid treatment and dewatering of material suspensions is disclosed including a pair of rotatable liquid permeable press rolls within a vat and in which the vat includes a bottom defining the space directed towards the nip between the press rolls and the remaining portion of the vat, and seals between the portions of the vat including a shoulder extending towards the bottom portion of the vat and an adjustable bar extending towards the remaining portion of the vat so the position of the bottom of the vat and the converging space in the direction towards the nip between the press rolls can be determined thereby.

Abstract: A number of distinct parallel digesters are fed with chips from a common steaming vessel. After steaming the chips are slurried and pressurized, and substantially simultaneously the steamed, slurried, and pressurized chips are transferred to at least some of (and typically each of) the distinct parallel digesters. A material stream is split into a number of individually controllable material streams (one for each of the digesters) either at the discharge from the steaming vessel, after slurrying (or at the discharge from a slurrying vessel), or after pressurizing (e.g. in a high pressure transfer device). For example a multi-branch conduit may be connected to the slurry outlet from the high pressure transfer device, the conduit having a branch directly connected to each of the digesters. A distinct return conduit may also be provided from each of the digesters to the high pressure transfer device, each return conduit preferably has a distinct flow control device and/or pump which are individually controlled.

Abstract: A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using one or more slurry pumps located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge. A return line from the top of the digester may, but need not necessarily, be operatively connected to the one or more pumps and if connected to the pumps the pressure in the return line may be reduced utilizing a pressure reduction valve and/or a flash tank. Steam from the flash tank may be used in steaming the chips.

Abstract: Liquor removal from particulate solids such as wet wood pulp is achieved by applying a pneumatic or vapor pressure force through a pad of the wood pulp to compress the solids and to expel liquor from the solids. If air is used as a displacing medium, no wash liquor is added and the solids are simply compressed and some of the liquor is replaced by the gas passing through the suspension. If steam is used, not as a heating medium but as a pressure medium, an increase in liquor removal occurs over and above that removed by gas only due to the condensation of the steam to form a liquid front travelling before the steam through the solid suspension. Hence, in principle, a combination of pressure washing and displacement occurs resulting in a high efficiency in washing. Gas or steam could therefore simply be applied to any conventional operation to increase the washing efficiency both by compression and by displacement.