Abstract: A method for manufacturing dissolving pulp using wood material is disclosed. The method comprises subjecting the wood material to a hydrothermal treatment using steam and/or water, digesting the wood material obtained to a pulp in a kraft cooking process; subjecting the pulp to a cold caustic extraction CCE; and dewatering, washing and pressing the pulp to get a pulp product having a carbohydrate content. The wood material can be a coniferous wood material, and whereby the mild hydrothermal treatment is performed to reach a P-factor of from 100-300, and whereby the cold caustic extraction is executed to reach a combined concentration of anhydromannose and anhydroxylose of 5 weight %, or less, of the carbohydrate content of the pulp product.

Abstract: The present invention provides a method for efficiently producing monosaccharides, oligosaccharides, and furfurals from biomass. A biomass is hydrolyzed under conditions under which monosaccharides, oligosaccharides, and furfurals are produced while continuously supplying an aqueous suspension of the biomass from a supply port of a continuous primary hydrolysis device and moving the suspension through the device. A hydrolysis solution is continuously discharged from a discharge port of the continuous hydrolysis device, and a hydrolysis solution containing monosaccharides, oligosaccharides, and furfurals are extracted from an intermediate extraction port provided at any position between the supply port and the discharge port of the continuous primary hydrolysis device. The extracted hydrolysis solution is then subjected to secondary hydrolysis.

Abstract: The invention relates to processes for manufacturing pulp and more specifically to improved processes for manufacturing dissolving pulp. The processes have primarily been developed to be used in connection with large scale kraft processes, i.e. they have been designed to be incorporated into a plant. A liquor derivable from the process and comprising xylan, lignin, alkali and water is also disclosed as well as a dissolving pulp produced by the process.

Abstract: A process for making bleached pulp comprises contacting an unbleached pulp mixture with a first recycled filtrate obtained from a first location (3) of a first recycled filtrate loop, to obtain a first pulp mixture having a first consistency; bleaching the first pulp mixture, to obtain a first bleached pulp mixture; pressing or dewatering the first bleached pulp mixture, to obtain a first pressed bleached pulp mixture and a second filtrate; sending at least a portion of the second filtrate to a second location (5) of the first recycled filtrate loop, wherein the second location (5) is downstream of and in fluid communication with the first location (3); contacting the first pressed bleached pulp mixture with a second recycled filtrate obtained from a third location (6) of the first recycled filtrate loop, to obtain a second pulp mixture having a second consistency, wherein the second consistency is greater than the first consistency, and wherein the third location (6) is downstream of and in fluid communicati

Abstract: The method and arrangement are for adding treatment liquid to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. The process is using a down-flow vessel wherein chips are descending down the vessel in a plug flow and wherein treated chips are continuously fed out at the bottom of the vessel. By arranging at least one telescopic pipe inside the vessel that extends down into the plug flow makes it possible to adjust the position for the addition of treatment liquid depending on current operational parameters.

Abstract: The invention relates to a method or methods of operating an apparatus for treating material by cutting, soaking and/or washing of the material, wherein the apparatus comprises a receptacle, a discharge element with a vortex generator and a pump arranged to pump fluid and material from the receptacle towards the vortex generator, wherein the vortex generator and the pump in combination are adapted to generate a vortex in the form of a conic helix in the fluid extending into the receptacle.

Abstract: The withdrawal screen section is for impregnation of chips during the manufacture of chemical pulp. Chips are steamed and impregnated in a low pressure impregnation vessel using pressurized hot spent cooking liquor BL. The spent cooking liquor produces most of the steam BLST necessary for steaming the chips. To reduce the need for adding fresh steam for chip steaming is a first withdrawal section in the impregnation vessel modified to be used both as a flash tank for warm pressurized wash filtrate and improved wash-out feature for the spent impregnation liquid behind the screen in the withdrawal section. The withdrawal volume is arranged with an upper part located above the liquid level LIQLEV of the impregnation vessel. Additional pressurized warm wash liquor REC1 is added to the withdrawal volume and flashed off steam is led in a steam duct to the chip volume above the liquid level.

Abstract: The first invention aims to provide a method for preparing stiffer bulky pulp at a freeness level comparable to that obtained by mechanical treatments to improve the bulkiness of product paper by searching for a method capable of adjusting freeness while suppressing damage to pulp fibers and internal fibrillation in a process for producing pulp. The second invention aims to strip contaminants deposited on pulp fibers and/or inorganic particles to reduce adhesion of the contaminants and decrease microorganisms in a treatment of process water containing long pulp fiber fractions used in a process for producing pulp and paper, thereby clarifying process water and thus preparing high-quality pulp and paper.

Abstract: A circular utilization method in pulping and papermaking processes with straw Primary pulp is obtained by digesting straw raw material according to the ammonium sulfite method. Concentrated black liquor is extruded from the primary pulp; paper pulp and diluted black liquor. The concentrated black liquor and the diluted black liquor are mixed, and a contaminated condensate is obtained. A residual concentrate or the concentrated black liquor is used for preparing a fertilizer. The contaminated condensate is mixed with one or more of the waste material obtained from stock preparation, a crop byproduct or organic waste, and substrate or fertilizer is obtained by fermenting the nitrogen source of the contaminated condensate or ammonium sulfite, or using the contaminated condensate for desulfurizing flue gas. Ammonia and flue gas are reacted to obtain the ammonium sulfite as a digestion agent; and water from recycling is used in corresponding phases of the pulping process.

Abstract: A method of defibring lignocellulose-bearing raw material with a polysulphide-bearing cooking liquor in a continuous digester. The cooking liquor is mixed into the raw material which is to be defibred before the cooking, and the cooking liquor is allowed to absorb into the raw material at a temperature which is at maximum approximately 130° C. The cooking liquor is then separated from the treated raw material, heated to a temperature of approximately 140-170° C., and mixed back into the treated raw material, possibly together with a fresh feed of cooking liquor, whereby the raw material is defibred to generate pulp which has a desired kappa number.

Abstract: The invention describes a process for the conversion of aqueous solutions of lignocellulosic solids comprising a solids content of between 1 and 20% of dry material, said process comprising a step a) for compression of said solution so as to separate the liquid phase present in and between the solids from the compressed solid phase and a step b) for extraction of at least the liquid phase, said liquid phase then being homogenised by heat and/or chemical treatments and reinjected on to the compressed solid phase.

Abstract: A continuous flow wood processing technology for extracting lignin from woody plant material and converting the delignified cellulosic residue to crude bio-oils is provided. Wood is chipped before processing starts and fed into a lignin extractor. The lignin extractor uses ethanol at high temperatures to dissolve the lignin with counter current material contactors. The ethanol containing dissolved lignin is removed from the lignin extractor, the dissolved lignin recovered, the ethanol and residual heat being recycled into the lignin extractor. The delignified cellulosic pulp is removed from the lignin extractor and subjected to a milling operation to convert the pulp into a smooth sludge for entry to a bio-convertor by a super critical water process. The product from this convertor is hydrocarbon sludge with a principal component being a kerogen. In a separate process crude oil is extracted from this sludge and the residue is prepared as a high phosphate Fertilizer.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. In one embodiment, the pre-extraction step involves contacting the lignocellulosic material with an aqueous solution under conditions that release acidic material from the lignocellulosic material into the aqueous solution, and the aqueous solution includes a basic material that at least partly neutralizes the acidic material so that the aqueous solution at the end of the pre-extraction step has a pH within a range of from 4.5 to 11. The process also includes a pulping step, after the pre-extraction step, in which the lignocellulosic material is separated into pulp. The process further includes an adsorption step, after the pulping step, in which hemicellulose is adsorbed on the pulp.

Abstract: The invention relates to a method for the simultaneous storage and drying of sewage sludge, comprising the following steps: a) mechanically dewatering the sewage sludge down to a dry substance concentration of 10 to 35 percent; b) applying the dewatered sewage sludge to a floor of a greenhouse-type drying hall in which a transparent building envelope forms the roof over the floor; c) drying the sewage sludge using solar radiation that radiates into the drying hall; d) mechanically dewatering additional sewage sludge down to a dry substance concentration of 10 to 35 percent; e) introducing the dewatered additional sewage sludge into the drying hall and mixing the additional sewage sludge with the sewage sludge already in the drying hall; f) drying said mixture using solar radiation that radiates into the drying hall; and g) evacuating the mixture from the drying hall or repeating steps d) to f), wherein in step e), the additional sewage sludge is mixed with the mixture in the drying hall rather than with the s

Abstract: A method of defibring lignocellulose-bearing raw material with a polysulphide-bearing cooking liquor in a continuous digester. According to the present invention, cooking liquor is mixed into the raw material which is to be defibred before the cooking, and the cooking liquor is allowed to absorb into the raw material at a temperature which is at maximum approximately 130° C. After that, cooking liquor used for the absorption is separated from the raw material which is treated in this way, the separated cooking liquor is heated to a temperature of approximately 140-170° C., after which the generated hot cooking liquor is mixed back into the treated raw material, possibly together with a fresh feed of cooking liquor fresh feed, and the raw material is defibred by means of the hot cooking liquor in a continuous digester in order to generate pulp which has a desired kappa number.

Abstract: A method of treating and utilizing liquid flows at a chemical pulp mill including stages for: a) chemical pulp is produced in an alkaline cooking process, b) the brown stock generated in the cooking is treated, said treatment comprising washing of the stock and preferably oxygen delignification and subsequent washing of the stock, c) a bleaching process for the brown stock, the bleaching sequence comprising at least one stage using chlorine dioxide and additionally at least one oxidizing bleaching stage and having at least two washing stages for treating the stock with liquids and for producing filtrates, and d) filtrates from stage c) are purified at an effluent treatment plant of the chemical pulp mill, which comprises at least biological treatment, for obtaining purified effluent. The method further includes a stage e), where the purified effluent with a color of 200 mg/l (Pt color) or more and a COD value of over 150 mg/l is used as pulp treatment liquid in stage c).

Abstract: The method increases the yield and improves the beatability of kraft pulp. During the progression of the cooking process, more than one cooking liquor with a dissolved content of hemicellulose is drawn off and then reintroduced to the last phases of the cooking process, to re-precipitate the hemicellulose on the fibers. The hemicellulose rich cooking liquors are adjusted so that they, upon being added to the last phase of the cooking process are optimized. Early dissolved hemicellulose has a longer chain length than the hemicellulose that dissolves in the cooking liquor in the later phases of the cooking process, and they also have different tendencies to precipitate on the wood chips softened in the cooking process.

Abstract: According to one embodiment of the invention, a system for processing biomass includes a water-impermeable bottom liner, a gravel layer supported by the bottom liner, a drain pipe disposed within the gravel layer, a biomass input device operable to deliver biomass over the gravel layer to form a biomass pile, a lime input device operable to deliver lime to the biomass for pretreating the biomass, a distribution pipe elevated above the gravel layer, and a pump operable to circulate water through the biomass pile by delivering water to the distribution pipe and receiving water from the drain pipe after it has traveled through the biomass pile. According to another embodiment, a method for biomass pretreatment with alkali, conducted at ambient pressure for approximately 4-16 weeks at temperatures ranging from approximately 25° C. to 95° C. Biomass may be lignocellulosic biomass and may be rendered suitable for enzymatic digestion or pulp production.

Abstract: An improved method for treating lignocellulosic material, including a prehydrolysis-mass transfer process, which produces a concentrated hydrolysate volume during the time required for the hydrolysis itself. The improved process comprises the heating of the digester and chip content by direct steam to the required hydrolysis temperature, starting a flow of hot, stored hydrolysate to the top of the chip bed in order to create a trickle-bed type down-flow of hydrolysate, collecting a first fraction of the trickled-down hydrolysate as a product fraction, adding extraction liquid and continuing the trickle flow to collect a second hydrolysate fraction, which will be discharged from the digester to a hot hydrolysate storage tank to be used as the first trickle flow liquid in the next batch.

Abstract: The system and method reduce the liquid/wood ratio at the top of a vapor phase digester in a continuous digester plant. Chips that are to be cooked in the vapor phase digester are fed as a mixture of chips and liquid at a liquid/wood ratio that exceeds 8:1 in a transfer line to an inverted top separator arranged at the top of the vapor phase digester. The top separator feeds the chips upwardly. More than 50% of the liquid content of the mixture of chips and liquid is withdrawn in the top separator and the remaining liquid is fed out from the top separator to the top of the vapor phase digester. A pile of chips and a liquid volume are established at the top, wherein the pile of chips is disposed above the liquid surface of the liquid volume.

Abstract: A system for collecting ligno-cellulosic biomass over a large area to enable the commercial refining of biomass from 2,500 to in excess of 50,000 tons of biomass per day to produce ethanol or other products. The biomass is collected at a series of collection points and then transported through a network of conduit “loops” interconnecting each of the collection points and the central refining plant. The water used to transport the biomass, as a slurry, is recovered and sequentially recycled in the same pipeline system to push the biomass slurry around the system in a “loop.” The outgoing and return legs of each loop optionally are located adjacent each other.

Abstract: A system for collecting ligno-cellulosic biomass over a large area to enable the commercial refining of biomass from 2,500 to in excess of 50,000 tons of biomass per day to produce ethanol or other products. The biomass is collected at a series of collection points and then transported through a network of conduit “loops” interconnecting each of the collection points and the central refining plant. The water used to transport the biomass, as a slurry, is recovered and sequentially recycled in the same pipeline system to push the biomass slurry around the system in a “loop”.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. In one embodiment, the pre-extraction step involves contacting the lignocellulosic material with an aqueous solution under conditions that release acidic material from the lignocellulosic material into the aqueous solution, and the aqueous solution includes a basic material that at least partly neutralizes the acidic material so that the aqueous solution at the end of the pre-extraction step has a pH within a range of from 4.5 to 11. The process also includes a pulping step, after the pre-extraction step, in which the lignocellulosic material is separated into pulp. The process further includes an adsorption step, after the pulping step, in which hemicellulose is adsorbed on the pulp.

Abstract: The method increases the yield and improves the beatability of kraft pulp. During the progression of the cooking process, more than one cooking liquor with a dissolved content of hemicellulose is drawn off and then reintroduced to the last phases of the cooking process, to re-precipitate the hemicellulose on the fibers. The hemicellulose rich cooking liquors are adjusted so that they, upon being added to the last phase of the cooking process are optimized. Early dissolved hemicellulose has a longer chain length than the hemicellulose that dissolves in the cooking liquor in the later phases of the cooking process, and they also have different tendencies to precipitate on the wood chips softened in the cooking process.

Abstract: The invention relates to an apparatus for continuous digestion of wood chip comprising an upright generally cylindrical vessel having a top end and a bottom end. The top end of the cylindrical vessel is adapted to receive wood chips mixed with a cooking liquor to be treated therein. A first conduit is integrally attached at a first location positioned between the top and bottom ends of the vessel for selectively extracting a first quantity of cooking liquor from the vessel. The first location is positioned upstream of a second location within the vessel where the cooking liquor being at substantially full cooking temperature. A second conduit is integrally attached at a third location positioned downstream from the first and second locations of the vessel.

Abstract: The invention describes a process for the conversion of aqueous solutions of lignocellulosic solids comprising a solids content of between 1 and 20% of dry material, said process comprising a step a) for compression of said solution so as to separate the liquid phase present in and between the solids from the compressed solid phase and a step b) for extraction of at least the liquid phase, said liquid phase then being homogenised by heat and/or chemical treatments and reinjected on to the compressed solid phase.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. Then, in a solvent pulping step, the lignocellulosic material is separated into pulp by contacting the lignocellulosic material with a cooking liquor comprising a solvent. In one embodiment, the solvent has a boiling point of at least about 150° C. In another embodiment, the cooking liquor comprises a mixture of solvent and water.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. In one embodiment, the pre-extraction step involves contacting the lignocellulosic material with an aqueous solution under conditions that release acidic material from the lignocellulosic material into the aqueous solution, and the aqueous solution includes a basic material that at least partly neutralizes the acidic material so that the aqueous solution at the end of the pre-extraction step has a pH within a range of from 4.5 to 11. The process also includes a pulping step, after the pre-extraction step, in which the lignocellulosic material is separated into pulp. The process further includes an adsorption step, after the pulping step, in which hemicellulose is adsorbed on the pulp.

Abstract: A method for converting a vapor phase continuous digester to a hydraulic digester including the steps of: operating the vapor phase digester in a vapor phase mode wherein a chip slurry enters the vessel of the digester through a lower chip inlet port, moves up through a top separator, discharges from an upper chip discharge chute of the separator to an upper vapor region of the vessel and falls to a liquor filled region of the vessel; ceasing the flow of the chip slurry to the separator; establishing a chip slurry flow path to an upper portion of top separator, and filling the vessel with liquor and chips such that the chip discharge chute is immersed in liquor.

Abstract: The arrangement concerns an improved design for at least one of the cooling, dilution and washing at the bottom of a continuous digester for the production of cellulose pulp. By arranging at least one extra strainer section above the lowermost strainer section, with the addition of washing fluid or dilution fluid between the extra strainer section and the lowermost strainer section, more washing fluid can be added at the bottom of the digester without counteracting the flow of the column of chips. This provides space for the increase of production, for improvement of the flow of the column of chips, or for combinations of these effects while retaining good cooling, washing and dilution at the bottom of the digester.

Abstract: A vessel is constructed with (preferably substantially stationary) screen surfaces which minimize compaction of comminuted cellulosic fibrous material, and allow springback of the material, as it flows downwardly. A slurry of wood chips, sawdust, or pulp is passed downwardly past one or more screen surfaces, which have a number of parts, including at least a first perforated part through which liquid is extracted, and a substantially solid part substantially immediately adjacent and below the first part which has a step out to relieve compaction and allow springback of the material.

Abstract: A method for adding cooking liquor into a vapor phase continuous digester for producing chemical cellulose pulp from cellulose chips including: introducing a slurry of the cellulose chips from a feed system to an inverted top separator in a top vapor phase section of the digester; distributing the slurry of the cellulose chips from the top separator into the vapor phase section of the digester; passing liquor through a conduit included with the drive shaft assembly of the top separator, and introducing the liquor from the conduit into the slurry as the slurry flows through the top separator or is distributed from the separator into the vapor phase section.

Abstract: The method is for pre-treatment of chips that are fed to a sulphate cooking process. Through acidification of the chips in an acidic treatment fluid with a subsequent draining of free treatment fluid before subsequent steaming or wet-steaming, a high concentration of free hydrogen ions is established within the chip pieces. When the chips are subsequently formed into slurry with preferably a sulphide-rich alkali cooking fluid, H2S is formed locally in the chip pieces which gives a yield-increasing effect in the subsequent cooking step of 1-3%.

Abstract: The present invention serves for loading a pulp suspension (S) with calcium carbonate. Liquid calcium hydroxide as milk of lime (7) is added during or before the pulp operation (1) carried out to form the pulp. By introducing gaseous carbon dioxide (8) into the pulp suspension thus treated, a chemical reaction is triggered therein, in which the finely divided calcium carbonate is precipitated. The present invention is particularly economic and effective due to the early addition of calcium oxide or calcium hydroxide.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. Then, in a solvent pulping step, the lignocellulosic material is separated into pulp by contacting the lignocellulosic material with a cooking liquor comprising a solvent. In one embodiment, the solvent has a boiling point of at least about 150° C. In another embodiment, the cooking liquor comprises a mixture of solvent and water.

Abstract: A continuous and batch system to produce cellulose, native lignin and unicellular protein from any form of vegetation in a closed process. The biomass is mixed in the impregnate solution of nitric acid and/or ammonium hydroxide and water. After a period of time at room temperature and atmospheric pressure the chemical solution is recycled. The biomass is moved to the reactor and heated. Evaporated impregnate is recovered via absorption tower and recycled back to chemical solution. The biomass is moved to an alkaline solution, then cooled to separate pulp from black liquor. The black liquor is pumped to a separation tank and is treated to precipitate lignin. The solution is filtered to separate sweet liquor and lignin. The lignin is dried and the sweet liquor is fermented to produce unicellular protein.

Abstract: A process for removing silica from nonwood plant materials involving both chemical and mechanical action is described. The silica-rich epidermal cells are liberated mechanically by a pre-pulping and low-consistency refining step and subsequently removed from the pulp via the filtrate of a thickening step. Amorphous silica is liberated chemically by using an alkaline dilution source in the pulper, then removed from the pulp via the filtrate of a thickening step and a dewatering step. The silica is then removed from the filtrate by adjusting the pH, followed by a separation step. The desilicated fibrous material may then be chemically or mechanically pulped and bleached using known processes. The silica removed from the nonwood plant material may then be used as a feedstock for other applications.

Abstract: A continuous digester for producing chemical cellulose pulp from cellulose chips including: a digester vessel with an upper section attached to a top separator and said vessel at least partially filled with the cellulose chips and a liquor; a top separator at least partially in said upper section having a lower chip inlet port, a chip conveyor, a screen adjacent the conveyor, an upper chip discharge chute, and a liquor outlet facing a side of the screen opposite to the conveyor, and a chip inlet conduit extending into the vessel and having a first operational mode in fluid communication with the chip inlet port and a second operational mode in which the chip inlet conduit discharges directly into the vessel.

Abstract: A process for high temperature peroxide bleaching of pulp in which pulp is retained at high temperature and pressure to increase bleaching activity but in which the pulp is cooled prior to discharge from the pressure vessel below the flash point thereby resulting in lower energy, nonviolent discharge. Through the use of a heat exchanger, the cooling of the pulp can be performed using recycled filtrate containing residual peroxide, which encourages further bleaching during atmospheric retention. The heat exchanger is also used to heat a water stream, which can be used earlier in the pulping process, resulting in cost savings because energy within the system is retained to a greater degree.

Abstract: The continuous digester is for producing chemical pulp to a process for operating this digester and to a feedback system for the cooking liquid. By means of implementing cooking zones 1st, 2nd, 3rd, 4th and 5th down through the digester, that have a successively decreasing liquid-to-wood ratio, it is possible to obtain a more uniform alkali profile during the cooking. The alkali is kept high at the beginning by means of a high liquid-to-wood ratio, typically over 6:1, which exceeds conventional liquid-to-wood ratios, which are normally around 3.5-5.0:1.

Abstract: Separation of dissolved and colloidal high molecular weight organic by-products from liquors or filtrates in a cellulosic pulping process to improve the overall efficiency of the process.

Abstract: The invention concerns a simplified method for the continuous cooking of wood raw material in the form of sawdust for the production of cellulose pulp, The method does not require any thickening stages and can be carried out with a minimum of process equipment. The complete process can be established with a steaming vessel, a cooking vessel and a subsequent pressure diffuser while the sawdust is mixed with the cooking fluid to form a slurry. The slurry has a consistency that throughout the process does not exceed 20%. The maximum consistency is preferably held at a maximum consistency of about 15-17%.

Abstract: The method is for the manufacture of cooked cellulose pulp in which the starting material, preferably chips, undergoes a successive increase in temperature towards cooking temperature. This is done while the chips are first treated in a pre-treatment zone in which the main part, greater than 50%, of fresh white liquor necessary for the cooking stage is added, after which this alkali-rich treatment fluid is withdrawn and replaced to a major extent by black liquor. The alkali-rich treatment fluid that has been withdrawn after the pre-treatment stage is then added to the cooking stage, which is why the addition of fresh white liquor to the cooking stage is reduced to an equivalent amount. Maximal yield-enhancing effect is obtained using poly-sulphide-rich white liquor during the pre-treatment at a temperature in the interval 60±40° C. and retention time in the interval 2-60 minutes, preferably 2-10 minutes.

Abstract: One aspect of this invention relates to a method and digester for reducing the deposition of calcium-based scale in a wood chip digester including extraction from the digester of first and second quantities of cooking liquor having respective first and second calcium concentrations, treating the extracted cooking liquors to produce a cooking liquor having a calcium concentration less that the calcium concentration of the either of the first and second extracted cooking liquors, and, reintroducing the treated cooking liquor to the digester. Another aspect of this invention relates to a method and digester in which through put through the digester is increased by the continuous addition of process liquor into the digester preferably at an upper region of the digester.

Abstract: The process is for continuously cooking chemical pulp in a digester system consisting of at least one vessel for impregnating and cooking comprising an inlet into which a mixture of chips and process liquid is fed. The chips are impregnated at a predetermined impregnation temperature, Timp, and cooked at a predetermined cooking temperature, Tcook, after which dissolved pulp is fed out at the outlet of the digester system. The process liquid which is continually extracted is retained outside the digester system during a dwell time, t, of at least 30 min, without any heating above 140°, and thereafter returned to the digester system to a position which is substantially at the same level as the extraction, or downstream thereof, and thereby constitute part of the process liquid in the subsequent treatment zone. The process results in improved tear strength, beatability, bleachability and reduced color reversion, and increased yield across the digester.

Abstract: The process is for continuously cooking chemical pulp in a digester system consisting of at least one vessel for impregnating and cooking comprising an inlet into which a mixture of chips and process liquid is fed. The chips are impregnated at a predetermined impregnation temperature, Timp, and cooked at a predetermined cooking temperature, Tcook, after which dissolved pulp is fed out at the outlet of the digester system. The process liquid which is continually extracted is retained outside the digester system during a dwell time, t, of at least 30 min, without any heating above 140°, and thereafter returned to the digester system to a position which is substantially at the same level as the extraction, or downstream thereof, and thereby constitute part of the process liquid in the subsequent treatment zone. The process results in improved tear strength, beatability, bleachability and reduced color reversion, and increased yield across the digester.

Abstract: Separation of dissolved and colloidal high molecular weight organic by-products from liquors or filtrates in a cellulosic pulping process through a filtration media to improve the overall efficiency of the process.

Abstract: A method in bleaching of pulp is described, in which the pulp is subjected to a peroxide bleaching step, whereupon the pulp is washed and the washing liquid from the washing is separated from the pulp in the form of a filtrate. The method is characterised in that the filtrate is treated with an aluminium compound, such as aluminium sulphate or polyaluminium sulphate, for precipitation of interfering substances, such as oxygen-demanding organic material and metals, that the precipitated material is removed from the filtrate, that the aluminium content of the filtrate after precipitation of interfering substances is adjusted to at most 20 ppm, and that the filtrate is then recirculated to the peroxide bleaching step. By the method, a reduced consumption of hydrogen peroxide in the peroxide bleaching step is achieved.

Abstract: A fiber mat is formed on a screen cylinder of a pressurized fiber filtering device used to filter particles from a liquid stream. The fiber mat is a fine particle filter to remove small particles from the liquid stream. The fiber mat is formed by injecting cellulosic fibers into the liquid stream flowing into the fiber filtering device. These fibers collect on the screen cylinder as the liquid flows through the cylinder. The collection of fibers forms the fine filtering mat.

Abstract: Systems and methods by which to subject cellulosic fibers to alkaline treatment are provided. The systems and methods of the invention include equipment, such as nanofiltration units and slurry concentrators, which result in a lowered overall consumption of alkaline solution during alkaline treatment. The systems and methods of the invention further allow the components of hemicaustic streams produced by such alkaline treatments to be utilized in higher value end uses.