Abstract: A method and an arrangement for generating process steam at a chemical pulp mill. Water is heated by subjecting it to an indirect heat exchange contact with steam in a heat exchanger. The water is heated with live steam produced in a steam boiler for generating process steam, whereby the live steam is condensed and the generated condensate is recovered. The process steam is subjected to a direct heat exchange contact with a material for heating the material. The water used for process steam production is obtained from secondary condensates, purified waste water and/or raw water. Process steam can be used in the treatment of cellulosic fibrous material, such as chips.

Abstract: The present invention relates to a process for producing cellulose with low inorganic impurities from sugarcane bagasse, the process comprising treating prehydrolysed sugarcane bagasse with a mixture of sulfite and at least one alkali to obtain residue having undissolved cellulose along with lignin rich liquor. The residue having undissolved cellulose is further subjected to delignification and addition of at least one enzyme to obtain a cellulose rich pulp. The cellulose rich pulp obtained is then treated with bleaching agents followed by separating pure cellulose rich pulp having high a-cellulose content and low inorganic impurities.

Abstract: The present process relates to thermally hydrolyzing sludge in a thermal hydrolysis system. A flash tank or waste heat boiler is located downstream of the thermal hydrolysis system. Hydrolyzed sludge is continuously directed into the flash tank or waste heat boiler for recovering supplemental steam. The supplemental steam is used independently or in combination with live steam produced by a main boiler to heat sludge being directed into the thermal hydrolysis system.

Abstract: The invention relates to a continuously operational method for thermal hydrolysis of organic matter, which includes an impelling step in which the organic matter is conveyed, without the need to use pumps or other mechanical elements, a hydrolysis step in which the mass to be hydrolyzed is heated using live steam until reaching high temperatures in very short times and, after undergoing a first breakdown of the structure, is maintained at the hydrolysis temperature during a predetermined time, and an energy recovery step with vapors of two enthalpy levels. The invention also relates to a facility for implementing the method, which includes interconnected load and pressurization tanks in the impelling step, a quick mixer and a relief chamber in the hydrolysis step, and a decompression system with a flash chamber and an ejector that mixes the produced vapors in the recovery step.

Abstract: The arrangement and method for the steam pre-treatment of chips during the production of cellulose pulp avoids the blow-through of gases in the steam pre-treatment vessel. This prevents foul-smelling gases from being released into the atmosphere. The inlet of the vessel has an inclined feeder device in a feeder-housing. In the event of the initiation of the risk for blow-through of steam, the feeder housing is sprayed with cooling liquid in order to increase condensation capacity of the chips being fed into the vessel. Ultimately the feeder housing is filled with liquid that establishes a liquid lock, and preferably at the same time as the feeder drive (M) is shut off. This avoids the emission of gases from the chip bin when interruptions in the process occur so that the release of odors into the surroundings is minimized.

Abstract: The feed system is for a continuous digester where at least two pumps are arranged in parallel at the bottom of a pre-treatment vessel and a stirrer is provided in direct connection to inlets to pumps. The system makes it possible to provide a feed system with an improved accessibility and operational reliability, and to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.

Abstract: A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.

Abstract: A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.

Abstract: A system, method and configuration for recovering turpentine during the manufacturing of wood chips, wood pellets or other substances that may include turpentine. In general, a turpentine recovery system is used to capture turpentine from exhaust of a dryer as wood chips are being dried. Advantageously, application of the various techniques disclosed herein can result in the recovery of turpentine that can then be sold to generate revenue and, may contribute to a reduction in the capital and operation costs for emission controls for the dryer exhaust.

Abstract: A method for producing mechanical paper pulp comprises: impregnating unprocessed wood, whereby unprocessed wood is exposed to an impregnating composition comprising at least a laccase enzyme and a formula mediator (I), wherein R1 and R2 are identical or different groups, chosen from among a hydrogen atom, a hydrocarbon chain, linear or branched, saturated or unsaturated, comprising 1 to 14 carbon atoms, wherein each hydrocarbon chain can be replaced by one or more functional groups chosen from among —OH, —SO3, benzyl, amino, mercapto, keto or carboxyl, wherein R1 and R2 in combination can form a cyclical structure, to achieve impregnation of the wood; and mechanically refining the impregnated wood, such that a mechanical paper pulp is obtained. The disclosure also relates to an impregnating composition used in this method and to the use thereof in a method for producing mechanical paper pulp, as well as to a method for producing paper.

Abstract: It is described a process for thermal hydrolysis and team explosion of biomass, said method comprising the steps of: (i) leading the biomass approximately continuous to a first preheating step and preheat the biomass, (ii) leading the preheated biomass into at least two reactors sequentially, (iii) heating and pressurising the reactor by addition of steam, (iv) keeping the reactor(s) at a certain temperature and pressure for a certain time, (v) leading the heated and pressurized biomass from the reactor(s) to a first pressure relief tank without any substantial pressure reduction and quickly relief the pressure of the biomass by means of a nozzle, in order to disintegrate the biomass, (vi) leading the biomass from the first pressure relief tank to a second pressure relief tank having a lower pressure than the pressure of the first pressure relief tank, (vii) leading the so treated biomass to a downstream facility for subsequent treatment. The invention also comprises a device for thermal treatment of biomass.

Abstract: Methods and systems for fractionating lignocellulosic biomass including hemicellulose, cellulose and lignin, including exploding the biomass cells to devolatilize the biomass, hydrolyzing the hemicellulose to produce a liquid component including hemicellulosic sugars and a solid component including less than 10% hemicellulose, separating the liquid and solid components, vaporizing the cellulose in the solid component, and condensing the cellulosic sugar vapors. The methods and systems may vaporize the cellulose in a continuous steam reactor at a temperature of about 400-550° C. and a pressure of about 1-3 bara. Electromagnetic and/or electroaccoustic treatment such as ultrasound and/or microwave treatment may be applied to the biomass immediately before or during cellulose hydrolysis.

Abstract: The invention relates to a process for producing a dissolving pulp from a cellulosic starting material using the kraft process, comprising the step of cooking the starting material with a cooking liquor. The process according to the invention characterized in that the starting material is exposed to a steam treatment prior to cooking and that the pulp obtained by cooking is subjected to cold caustic extraction (CCE) in the course of further processing.

Abstract: Sugarcane bagasse consists of mainly three polymeric components, namely cellulose (40-45%), hemicellulose (xylan) (28-30%), and lignin (19-21%). A process is herein disclosed for fractionating sugarcane bagasse into cellulose, hemicellulose and lignin with high purity ?-cellulose, which is a useful raw material for preparing cellulose esters like cellulose triacetate and other high value-added cellulose plastics. Co-production and recovery of hemicellulose (xylan) and lignin in high yields and high purities, along with ?-cellulose, is another important feature of this process. Sugarcane bagasse consists of a material known as pith which constitutes 30-35% by weight of bagasse. Pith contains cellulose, hemicellulose, and lignin, in addition to various other ingredients and cell mass. The process described herein discloses the use of partially depithed bagasse as a preferred raw material for fractionation.

Abstract: A method for generating steam in a digester plant of a chemical pulp mill including: producing black liquor in the digester plant, extracting a first stream of black liquor from the digester; generating vapor by evaporating the first stream of black liquor by heating the first stream with fresh steam; heating fibrous material in the digester with the generated vapor from the evaporated first stream of black liquor; extracting a second stream of black liquor from the digester; flashing the second stream of black liquor to generate flashed black liquor and flashed black liquor vapor; introducing the flashed black liquor vapor to at least one heat exchanger to indirectly heat a clean evaporable liquid to produce clean steam from the clean evaporable liquid; and steaming, with the clean steam produced in the at least one heat ex-changer, cellulosic feed material before feeding the cellulosic feed material to the digester plant.

Abstract: A process for treatment of fibers is disclosed. The treatment comprises simultaneously and continuously macerating the fibers and exposing the fibers to superheated steam, ammonia gas and ethylenediamine gas. The treatment is carried out in a chamber where the fibers are subjected to the mechanical rubbing and crushing action of a plurality of rotating pins against channels disposed on the chamber interior wall. The treatment results in improved fiber water holding capacity and improved conversion efficiency in the production of ethanol from the treated fibers.

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 pressurised 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 pressurised 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 pressurised 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: A method of producing a modified pulp comprising treating wood chips in an extraction process to remove hemicellose to form treated wood chips; and subjecting said treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 5 to about 10% by dry weight of the modified pulp.

Abstract: A process for the pretreatment of lignocellulosic biomass, in particular during the production of ethanol from biomass. The process including a cooking step where the biomass is exposed to steam at elevated temperatures and pressures for a preselected period of time in a treatment vessel. During the process, volatile and liquid compounds are purged from the treatment vessel.

Abstract: The invention concerns a method for producing a cellulose-containing mass comprising an organic material, the method comprising the steps a) preparation of an input comprising organic material and a liquid content, and b) exposing said input to a wet-mixing procedure at a temperature in the range of 40 to 90° C. preferably 50 to 80° C. and most preferred around 60° C.

Abstract: A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.

Abstract: A method for producing pulp by extracting hemicellulosic materials from lignocellulosic materials using water in an extraction stage, wherein the extraction stage is either a single extraction or a double extraction process; treating the lignocellulosic materials with an oxidizing agent in a treatment stage, wherein the treatment stage is selected from the group consisting of a second extraction process, an agent impregnation process, and a first pretreatment process; treating the lignocellulosic materials with a reducing agent in the treatment stage, wherein the treatment stage is selected from the group consisting of the second extraction process, the agent impregnation process, and a second pretreatment process; and then subjecting the lignocellulosic materials to a modified Kraft pulping process to produce pulp.

Abstract: A process for treatment of fibers is disclosed. The treatment comprises simultaneously and continuously macerating the fibers and exposing the fibers to superheated steam, ammonia gas and ethylenediamine gas. The treatment is carried out in a chamber where the fibers are subjected to the mechanical rubbing and crushing action of a plurality of rotating pins against channels disposed on the chamber interior wall. The treatment results in improved fiber water holding capacity and improved conversion efficiency in the production of ethanol from the treated fibers.

Abstract: A method of producing a modified pulp comprising treating wood chips in an extraction process to remove hemicellose to form treated wood chips; and subjecting said treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 5 to about 10% by dry weight of the modified pulp.

Abstract: The arrangement and method for the steam pre-treatment of chips during the production of cellulose pulp avoids the blow-through of gases in the steam pre-treatment vessel. This prevents foul-smelling gases from being released into the atmosphere. The inlet of the vessel has an inclined feeder device in a feeder-housing. In the event of the initiation of the risk for blow-through of steam, the feeder housing is sprayed with cooling liquid in order to increase condensation capacity of the chips being fed into the vessel. Ultimately the feeder housing is filled with liquid that establishes a liquid lock, and preferably at the same time as the feeder drive (M) is shut off. This avoids the emission of gases from the chip bin when interruptions in the process occur so that the release of odors into the surroundings is minimized.

Abstract: A process is defined for the continuous steam pretreatment and fractionation of bagasse to produce a concentrated cellulose solid stream that is sensitive to enzymatic hydrolysis. Valuable chemicals are recovered by fractionating the liquid and vapor stream composed of hydrolysis and degradation products of the hemicellulose. Cellulosic derived glucose is produced for fermentation to biofuels. A hemicellulose concentrate is recovered that can be converted to value added products including ethanol.

Abstract: It is described a process for thermal hydrolysis and team explosion of biomass, said method comprising the steps of: (i) leading the biomass approximately continuous to a first preheating step and preheat the biomass, (ii) leading the preheated biomass into at least two reactors sequentially, (iii) heating and pressurising the reactor by addition of steam, (iv) keeping the re-actor(s) at a certain temperature and pressure for a certain time, (v) leading the heated and pressurised biomass from the reactor(s) to a first pressure relief tank without any substantial pressure reduction and quickly relief the pressure of the biomass by means of a nozzle, in order to disintegrate the biomass, (vi) leading the biomass from the first pressure relief tank to a second pressure relief tank having a lower pressure than the pressure of the first pressure relief tank, (vii) leading the so treated biomass to a downstream facility for subsequent treatment.

Abstract: Methods of producing mechanical pulps from lignocellulosic material including partial defibration of lignocellulosic material in a chip press followed by liquid impregnation, preheating the lignocellulosic material for 20 seconds or less at a pressure between 7.5 and 12 bar (gauge) prior to mechanically refining the lignocellulosic material in a primary mechanical refiner at a pressure between 7.5 and 12 bar (gauge), thus obtaining a high freeness pulp.

Abstract: A fibrous material for small animal bedding material and methods for making the same. The fibrous material can be or include a plurality of lignocellulosic fibers derived from wood-based materials. The wood-based material can be a mixture of hardwoods and/or softwoods that are processed into individual fibers having varying lengths to form a matrix of fibers that is soft enough for small animal bedding, but rigid enough to maintain nest or burrow shape integrity after being created by the animal.

Abstract: The arrangement and method are for the steam pre-treatment of chips during the production of cellulose pulp to avoid the blow-through of gases in the steam pre-treatment vessel. This prevents foul-smelling gases from being released into the atmosphere. Spreader nozzles for the injection of cooling fluid are arranged in the gas phase of the steam pre-treatment vessel. In the event of the risk for blow-through of steam, cooling that is proportional to the risk is activated. It is possible to avoid the emission of gases from the chip bin when interruptions in the process occur, whereby the release of odors into the surroundings can be minimized.

Abstract: A system has been developed for pretreating cellulosic biomass feed stock including: a first pressurized reactor receiving the feed stock, wherein the feed stock undergoes hydrolysis in the first pressurized reactor; a sealing device having a first pressurized coupling to a feedstock discharge port of the first pressurized reactor, and a second pressurized coupling to a second pressurized reactor; a drain for a liquid including dissolved hemi-cellulosic material extracted from the feed stock in at least one of the first pressurized reactor and the sealing and extraction device; the second pressurized reactor assembly receiving the pressurized feed stock from the sealing device at a pressure substantially greater than the pressure in the first pressurized reactor, wherein cells of the feed stock are infused with water in the second pressurized reactor, and an expansion device downstream of the second pressurized reactor assembly, wherein the expansion device rapidly releases the pressure of the feed stock disc

Abstract: The vessel in which the chips are pre-treated with steam (ST) is provided with a ventilation channel at the top of the vessel for the leading away of weak gases to a weak gas system (NCG). A simple safety system has been installed with the aim of guaranteeing that these weak gases do not reach a level of concentration at which these weak gases become explosive. The safety system has a control unit (CPU) that detects a process parameter that is indicative of the fraction of moisture in the weak gases and opens dilution lines that supply air for the dilution of the weak gases in the ventilation channel. It is appropriate that the dilution take place in stages, where the dilution lines are opened in stages with successively increasing temperature of the weak gases.

Abstract: Disclosed are a method of hydrolysis of wet fiber and a method for preparing ethanol. Generally, an agricultural plant material, such as corn hulls, distiller's dried grains, or spent germ, is treated to at least partially hydrolyze the fiber. The process may include a maceration step followed by a shearing operation in the presence of steam to yield a treated product, in which, in many embodiments, saccharides will be released and unbound from fibrous portions of the agricultural product. In some embodiments, the process includes macerating the material to provide a slurry having a solids content of at least 10 percent and jet cooking the slurry. A mixture of saccharides prepared in this fashion may be fermented to yield ethanol and/or biochemicals.

Abstract: The present invention relates to a process for the production of xylose and dissolving pulp from xylan-containing biomass, such as hardwood. The invention is based on prehydrolysis of the xylan-containing biomass with SO2 in specified conditions, followed by chromatographic fractionation, nanofiltration or precipitation crystallization of the xylose-containing prehydrolyzate to obtain a xylose product having a xylose content of at least 55% on DS. The dissolving pulp obtained from the process can be used for example for the production of viscose.

Abstract: In a continuous digester system the digester system is greatly simplified by using a single vertical atmospheric vessel, replacing the conventional chip bin, steaming vessel, chip chute, high pressure pumping or sluice feeders, impregnation vessels and top separator. Chips are simply fed to the top of the atmospheric vessel, and a chip level is established in the vessel. Treatment liquids are added to the vessel such that a total liquid volume (Z1+Z2) with a liquid level (LIQ LEV) is established under the chip level (CH LEV). Impregnation stage and subsequent cooking stages are implemented in the atmospheric vessel at successively increasing temperature and depths into the total liquid volume, thus preventing boiling in the stages and preferably reducing steam blow trough of the chip surface in the top of the vessel.

Abstract: The method of the present invention is directed towards a method to increase the pulp yield of a lignocellulosic material, or increasing pulp bulk and/or pulp viscosity. This method comprises the following steps; preparing a lignocellulosic material, contacting the lignocellulosic material in a vessel with hot water or steam for a predetermined time, producing acetic acid from the reaction of the hot water or steam and the lignocellulosic material, lowering the pH to less than about 4, removing lignocellulosic material extracts including a large percentage of hemicellulose, acetic acid and metal ions, exposing contacted lignocellulosic material to pulping chemicals in a pulping reactor, forming a contacted lignocellulosic material pulp with a kappa number below about 19 after about 90 minutes of contact with the pulping chemicals, exposing the contacted lignocellulosic material pulp to whitening agents, and producing a whitened hot water contacted lignocellulosic material pulp.

Abstract: Processes for the preparation of prehydrolyzed pulp from lignin-containing cellulosic material are described including prehydrolyzing the cellulosic material with steam at a first pressure, terminating the prehydrolyzing by at least one addition of an alkaline liquid at the first pressure followed by at least one pressure reduction and delignifying the prehydrolyzed cellulosic material in a cooking stage. The pressure reduction can be a single pressure reduction or a gradual pressure reduction carried out in incremental stages.

Abstract: A system for thermomechanical refining of wood chips comprises preparing the chips for refining by exposing the chips to an environment of steam to soften the chips, compressively destructuring and dewatering the softened chips to a solids consistency above 55 percent, and diluting the destructured and dewatered chips to a consistency in the range of about 30 to 55 per cent. The destructuring partially defibrates the material. This diluted material is fed to a rotating disc primary refiner wherein each of the opposed discs has an inner ring pattern of bars and grooves and an outer ring pattern of bars and grooves. The destructured and partially defibrated chips are substantially completely defibrated in the inner ring and the resulting fibers are fibrillated in the outer ring.

Abstract: One aspect of the present invention relates to a method of processing lignocellulosic material, comprising initial steam pretreatment to give pretreated lignocellulosic material with an average particle size, followed by refining to give refined lignocellulosic material with an average particle size, wherein the average particle of the pretreated lignocellulosic material is greater than the average particle size of the refined lignocellulosic material. In certain embodiments, the lignocellulosic material is selected from the group consisting of grass, switch grass, cord grass, rye grass, reed canary grass, miscanthus, sugar-processing residues, sugar cane bagasse, agricultural wastes, rice straw, rice hulls, barley straw, corn cobs, cereal straw, wheat straw, canola straw, oat straw, oat hulls, corn fiber, stover, soybean stover, corn stover, forestry wastes, recycled wood pulp fiber, sawdust, hardwood, and softwood.

Abstract: A method for generating steam in a digester plant of a chemical pulp mill including: producing black liquor in the digester plant, extracting a first stream of black liquor from the digester; generating vapor by evaporating the first stream of black liquor by heating the first stream with fresh steam; heating fibrous material in the digester with the generated vapor from the evaporated first stream of black liquor; extracting a second stream of black liquor from the digester; flashing the second stream of black liquor to generate flashed black liquor and flashed black liquor vapor; introducing the flashed black liquor vapor to at least one heat exchanger to indirectly heat a clean evaporable liquid to produce clean steam from the clean evaporable liquid; and steaming, with the clean steam produced in the at least one heat ex-changer, cellulosic feed material before feeding the cellulosic feed material to the digester plant.

Abstract: A refiner steam separation system according to the present invention includes a blowline for transporting a mixture of fiber material from a refiner to an inlet of a steam separator. Waste steam is discharged from the separator through a waste steam outlet. Cleaned fiber material is discharged from the separator through an exit, which prevents a substantial portion of the waste steam from passing through the exit. A relay pipe communicates with the exit and a dryer duct, and transports cleaned fiber material therebetween. A resin input communicates with the relay pipe, and supplies resin therein. The resin is mixed with the cleaned fiber material prior to the cleaned fiber material being dried in the dryer duct. The present invention is also directed to a method of reducing VOC emissions generated during refining cellulosic fibrous material.

Abstract: A process for the pretreatment of lignocellulosic biomass, in particular during the production of ethanol from biomass. The process including a cooking step where the biomass is exposed to steam at elevated temperatures and pressures for a preselected period of time in a treatment vessel. During the process, volatile and liquid compounds are purged from the treatment vessel.

Abstract: A method of manufacturing bleached mechanical and chemithermomechanical pulp is provided, having enhanced bleaching effect, wherein lignocellulose material is passed through at least one preheater or through a chemical treatment system, a steam separator and a refiner where the lignocellulose material is converted into a pulp suspension which, after steam separation, is passed at least to a storage vessel and to a screening department, from which the major part of the pulp suspension is separated as a substantially finished product or is separated and further treated. The reductive bleaching agent is added to the advancing pulp suspension without a bleaching tower. The method is characterized by adding the bleaching agent at a location downstream of the refiner and upstream of the screening department, and by bleaching the pulp under drastic conditions of temperature and minimized oxygen access at the location and immediately downstream of the location.

Abstract: A method and an apparatus for processing wood chips, wherein the wood chips are treated with steam in a gas removal apparatus. The condensate formed in the gas removal apparatus is removed from the gas removal apparatus and the wood chips are treated with a processing solution in order to remove metal ions from the wood chips. Condensate formed in the gas removal apparatus is used as processing solution.

Abstract: A system for thermomechanical refining of wood chips comprises preparing the chips for refining by exposing the chips to an environment of steam to soften the chips, compressively destructuring and dewatering the softened chips to a solids consistency above 55 percent, and diluting the destructured and dewatered chips to a consistency in the range of about 30 to 55 percent. The destructuring partially defibrates the material. This diluted material is fed to a rotating disc primary refiner wherein each of the opposed discs has an inner ring pattern of bars and grooves and an outer ring pattern of bars and grooves. The destructured and partially defibrated chips are substantially completely defibrated in the inner ring and the resulting fibers are fibrillated in the outer ring.

Abstract: This invention relates to pulp reactivity enhancement. In particular, the invention relates to a method of producing an alkali cellulose which includes steps of providing a pulp and subjecting the pulp to an alkaline treatment to produce the alkali cellulose in the presence of a spacer capable of entering the holes in the interfibrillar spaces of the cellulose fibres. The spacer enters the holes in the interfibrillar spaces of the cellulose fibres, particularly those created by the removal of hemi-cellulose, reducing the tendency for collapse to occur, for example during the subsequent pressing step. Examples of suitable spacers are polyethylene glycols, polyvinyl alcohols and polyacrylates.

Abstract: The invention relates to a process for producing a dissolving pulp from a cellulosic starting material using the kraft process, comprising the step of cooking the starting material with a cooking liquor. The process according to the invention characterized in that the starting material is exposed to a steam treatment prior to cooking and that the pulp obtained by cooking is subjected to cold caustic extraction (CCE) in the course of further processing.

Abstract: The method and an arrangement are for improved impregnation of chips in association with the manufacture of chemical cellulose pulp. Un-steamed chips are fed into an impregnation vessel (30) in which a fluid level (LIQ_LEV) is established under the highest level (CH_LEV) of the chips. An improved impregnation arrangement for the chips is obtained by the addition of impregnation fluids (BL1/BL2/BL3) with increasing temperatures at different heights (P1, P2, P3), and by the establishment of a counter-flow zone (Z1) in the uppermost part of the impregnation vessel. The requirement for steaming may in this way be dramatically reduced while at the same time the amount of expelled waste gases may be minimized. A major part of the volatile compounds present in the wood are bound to the impregnation fluid (REC) that is withdrawn.

Abstract: A method for the fractionation of lignocellulosic materials into cellulose, hemicelluloses and lignin in a batch or continuous process in a treatment with vaporous mixture of aliphatic alcohol, sulfur dioxide and water. Cooking conditions are varied to get different proportions of cellulose, hemicelluloses and lignin. Chemical recovery through pressure release is described.

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.