Abstract: Provided herein is a process for hydrolyzing a cellulosic feedstock to produce sugar. The process comprises introducing a pretreated cellulosic slurry to an inlet region of a plug flow hydrolysis reactor using a slurry introduction device that reduces the axial momentum of the slurry at the surface of the reactor contents. The cellulosic feedstock slurry is hydrolyzed in the plug flow hydrolysis reactor by contacting the cellulosic feedstock with at least cellulase enzymes to produce glucose. Also provided herein is a vertically-oriented, unmixed downflow hydrolysis reactor for hydrolyzing a pretreated cellulosic feedstock slurry which comprises such a slurry introduction device disposed in a top region thereof.

Abstract: An air-sparged hydrocyclone for separating a vapor from a carrier gas is disclosed. The cyclone comprises a porous sparger covered by an outer gas plenum. A cryogenic liquid is injected to a tangential feed inlet at a velocity that induces a tangential flow and a cyclone vortex in the air-sparged hydrocyclone. The carrier gas is injected into the cyclone through the porous sparger. The vapor dissolves, condenses, desublimates, or a combination thereof, forming a vapor-depleted carrier gas and a vapor-enriched cryogenic liquid. The vapor-depleted carrier gas is drawn through a vortex finder and the vapor-enriched cryogenic liquid is drawn through an apex nozzle outlet. In this manner, the vapor is removed from the carrier gas.

Abstract: A method for separating a vapor from a carrier gas is disclosed. An air-sparged hydrocyclone is provided with a porous sparger covered by an outer gas plenum. A cryogenic liquid is provided to the tangential feed inlet at a velocity that induces a tangential flow and a cyclone vortex in the cyclone. The carrier gas is injected into the air-sparged hydrocyclone through the porous sparger. The vapor dissolves, condenses, desublimates, or a combination thereof, forming a vapor-depleted carrier gas and a vapor-enriched cryogenic liquid. The vapor-depleted gas is drawn through a vortex finder while the vapor-enriched cryogenic liquid is drawn through an apex nozzle outlet. In this manner, the vapor is removed from the carrier gas.

Abstract: A method for separating a vapor from a carrier gas is disclosed. A hydrocyclone is provided with one or more nozzles on the wall of the hydrocyclone. A cryogenic liquid is provided to the tangential feed inlet at a velocity that induces a tangential flow and a cyclone vortex in the hydrocyclone. The carrier gas is injected into the hydrocyclone through the one or more nozzles. The vapor dissolves, condenses, desublimates, or a combination thereof, forming a vapor-depleted carrier gas and a vapor-enriched cryogenic liquid. The vapor-depleted gas is drawn through the vortex finder while the vapor-enriched cryogenic liquid is drawn through the apex nozzle outlet. In this manner, the vapor is removed from the carrier gas.

Abstract: The feed system is for a continuous digester where at least two pumps are arranged in parallel in the bottom of a pre-treatment vessel and a liquid level of at least 20 meters is established. The system makes it possible to provide a feed system with an improved accessibility and more reliable operation, and to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.

Abstract: The feed system is for a continuous digester where at least two pumps are arranged in parallel in the bottom of a pre-treatment vessel and a liquid level of at least 10 meters is established. The system makes it possible to provide a feed system with an improved accessibility and more reliable operation, and to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.

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. The transfer to the top of the digester takes place without a conventional top separator. 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: 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: 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. Each pump has its own independent transfer line extending to the top of the digester. 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: 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 method to treat a lignocellulosic material including: performing a steam explosion reaction on the lignocellulosic material and discharging a slurry from the; adding an alkali material to the slurry in a first conveyor; transferring the slurry with the alkali material from the first conveyor to a second conveyor; adding an enzyme solution to the slurry while in, entering or at the discharge of the second conveyor; transferring the slurry with the enzyme solution from the second conveyor slurry to a mixer; mixing the slurry in the mixer, wherein a second portion of the enzyme solution is added to the slurry during the mixing, and transferring the slurry with the enzyme solution from the mixer to a first reactor vessel wherein the slurry in the first reactor vessel undergoing enzymatic hydrolysis such that the viscosity of the slurry is reduced in the first reactor vessel.

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. The outlets of the pumps are combined at a merging point before a common transfer line extends to the top of the digester. 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 method and apparatus for pretreating fibre material to be used in manufacturing paper or the like, for example, by precipitating mineral substances to the fibres. During precipitation, fibre material, which is advantageously pretreated in a through-flow mixer operating on the principle of an impact mill, is fed to the precipitation reactor. Gas is led to the precipitation reactor in order to generate a gas space in the reactor. The gas contains a substance, which precipitates the mineral substance such as carbon dioxide (CO2). The fibre material is fed to the gas space of to the precipitation reactor as small liquid and solid substance fractions such as drops and/or particles.

Abstract: A method and apparatus for pretreating fiber material to be used in manufacturing paper or the like, for example, by precipitating mineral substances to the fibers. During precipitation, fiber material, which is advantageously pretreated in a through-flow mixer operating on the principle of an impact mill, is fed to the precipitation reactor. Gas is led to the precipitation reactor in order to generate a gas space in the reactor. The gas contains a substance, which precipitates the mineral substance such as carbon dioxide (CO2). The fiber material is fed to the gas space of the precipitation reactor as small liquid and solid substance fractions such as drops and/or particles.

Abstract: The invention proposes an installation (10) in which the impregnation and fractionation of the raw material (MP) are conducted at atmospheric pressure, characterized in that it comprises means (18, 20) for transferring the raw material (MP) successively to a first treatment station (PT1) and a second treatment station (PT2), each comprising means (G1, G2) for temporarily combining, at the first station (PT1), the raw material (MP) with a quantity of a first mixture of organic acids and, at the second station (PT2), for temporarily combining the raw material (MP) with a quantity of a second mixture; and means, after impregnation, for at least partially recovering the quantity of second mixture after impregnation and for recycling at least a portion of the second recovered mixture to form at least partially said first impregnation mixture used at the first station (PT1).

Abstract: The present invention is directed to a continuous process for pretreating a lignocellulosic feedstock. A feedstock slurry is provided, which has a solids concentration of 10% to 33% by weight. The feedstock slurry is pumped through a heating train of at least two stages, each stage including a pump to increase stage pressure and a direct steam injection to heat the feedstock slurry. Acid is also added to the feedstock slurry prior to the heating train, during a heating stage, or after leaving the heating train; the acid is added at a concentration of 0% to 12% weight of acid on weight of initial feedstock. A heated, acidified feedstock slurry is thus produced. The heated, acidified feedstock slurry is flowed through a pre-treatment reactor at a temperature of 160° C. to 280° C. for a time sufficient to increase efficiency of conversion of cellulose in the feedstock to glucose using cellulase enzymes.

Abstract: A method to chemically treat light weight, bulky cellulosic material including: introducing the material to an upper inlet of a substantially vertical treatment vessel; maintaining the material in the vessel at a pressure of at least 20 bar and at a temperature of at least 200° C.; treating the material with a cooking liquor in the vessel; moving the material past at least one anti-compression ring on an inside surface of the vessel, as the material moves downward through the vessel; agitating the material in the vessel, and discharging the treated material from a lower discharge port of the vessel.

Abstract: An enhanced method of repulping paper and improving water quality by placing used paper product material in an aqueous solution of dipolar aprotic protophylic solvent, processing it, and recovering recycled pulp based on two physical reactions of the dipolar solvent: first with water from one part of the solvent, and second with cellulosic material from the other part of the solvent. The water reaction involves a rearrangement of hydrogen bonds within the water, improving its reactivity and solvent capacity, and the cellulosic reaction involves dissolution of hemicellulose in a manner which results in reduced fibre loss and improved pulp quality. The net result is more efficient pulping and reduced environmental impact.

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: An apparatus and method serves, e.g., to deaerate, clean or screen a fibrous suspension and is provided with a closed housing and a rotor arranged centrally therein. The rotor puts at least a part of the fibrous suspension guided into the housing into a rotational flow. The fibrous suspension flowing into the housing through the inlet is put into rotation by a guide element acting hydraulically. This increase the efficiency of the apparatus and prevents disturbing turbulences in the apparatus.

Abstract: An arrangement for and a method of treating pulp, and a method of modernizing a pulp tower are disclosed. The arrangement and method relate to treating pulp in connection with high-consistency pulp towers, and especially to means (36, 42) for diluting pulp arranged substantially at the level of the smallest cross-sectional area between the parting member (31) and the wall (12) of the pulp tower (10).

Abstract: A method to chemically treat light weight, bulky cellulosic material including: introducing the material to an upper inlet of a substantially vertical treatment vessel; maintaining the material in the vessel at a pressure of at least 20 bar and at a temperature of at least 200° C.; treating the material with a cooking liquor in the vessel; moving the material past at least one anti-compression ring on an inside surface of the vessel, as the material moves downward through the vessel; agitating the material in the vessel, and discharging the treated material from a lower discharge port of the vessel.

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: The invention relates to a method and a screen for screening two or more pulp mixtures with different roughness. The screen comprises a first screen cylinder and a second screen cylinder. A coarse first pulp mixture is fed into the inlet end of the first screen cylinder, and a second, less coarse pulp mixture is supplied to the second screen cylinder. The pulp mixtures are screened by means of a screen surface of the screen cylinders into accept that passes apertures provided in the screen surface and reject that does not pass the apertures. The accept from the second cylinder is conveyed by means of a guide tube provided between the cylinders towards the inlet end of the first cylinder and it is finally mixed with the first pulp mixture. The accept from the first and the second pulp mixture passes the screen surface of the first screen cylinder.

Abstract: Apparatus for the production of cellulose paper pulps from vegetative masses, comprising: a tower for sterilizing the mass to form a culture medium; a first screw for mixing the sterilized mass with an inoculum and handling the same in a sterile environment; a first conditioning and reaction chamber for mixing and handling the inoculated mass in a sterile environment and controlled atmosphere of CO2 and O2, with controlled temperature and pH; a hydraulic pulper for the elementarization of the mass and its soaking up with suspensions of enzyme mixes; a hammer mill for the elementarization of vegetative material, to break up knots of stems and to pulverize leaves, detach bast from wood; a rotating tumbler having reels and counter reels for separating various fractions; a rotor compactor to reduce the volume of the vegetable mass and to remove air contained in the same; a second screw for mixing the compacted vegetetative mass with extracts containing enzymes and with water for handling in a sterile environment;

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 a single vane slurry pump in series with a centrifugal slurry pump both of which are 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.

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: For a process and an apparatus for loading fibers contained in a pulp suspension with calcium carbonate, a calcium oxide and/or a medium containing calcium hydroxide is fed to the pulp suspension, and the so treated pulp suspension is further charged in several reactors with pure carbon dioxide or a medium containing carbon dioxide. The reactors can be connected in series and/or in parallel.

Abstract: The present invention relates to an arrangement in connection with bleaching pulp having a consistency of 7-20%, preferably 8-16%, said arrangement comprising a bleaching tower having at least one inlet opening and at least one outlet opening for pulp, a transfer line comprising a feed line operatively connected to the inlet of the tower and a discharge line operatively connected to the outlet of the tower, and at least one pump arranged in the feed line. The arrangement further comprises at least two propeller or turbine type devices for increasing the pressure of the pulp flowing in the transfer line.

Abstract: A method is disclosed for extracting liquor from a cellulose slurry for a continuous digester comprising the steps of: providing the cellulose slurry of liquor and chips of cellulose fiber material to a separator; extracting a first stream of liquor from the separator; extracting a second stream of liquor from the separator, where the second stream has an effective alkali (EA) concentration greater than the EA concentration of the first steam; outputting the first stream from the separator and outputting the second stream from the separator separately from the second stream, and outputting a condensed slurry from the separator to a digester vessel.

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: Provided is a process for bleaching pulp with ozone. The process involves preparing a slurry of cellulosic pulp having a consistency in fibers of from 1-5 weight %. Such a low consistency slurry is then mixed with ozone under high shear conditions. The ozone is then maintained in contact with the cellulosic fibers to effect bleaching of the fibers. The present process offers the advantages of bleaching using a low consistency slurry, with the added advantages of employing ozone.

Abstract: Method is disclosed for treating wood chips including a heater for preheating the wood chips in the presence of steam, a beater to mechanically process the wood chips into wood fibers, a cyclone for separating the wood fibers from steam and volatile organic substances produced in the beater, a blower line for transporting the wood fibers, steam and volatile organic substances from the beater to the inlet of the cyclone, a drying conduit connected to the lower outlet of the cyclone for carrying wood fibers therefrom, a sluice valve associated with the lower outlet of the cyclone for controlling the removal of the wood fibers from the cyclone, and a processing conduit connected to the upper outlet of the cyclone for the steam and the volatile organic substances whereby the volatile organic substances separated in the cyclone can be separated and heat associated with the steam separated in the cyclone can be recovered.

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: Apparatus for the production of cellulose paper pulps from vegetative masses, comprising: a tower for sterilizing the mass to form a culture medium; a first screw for mixing the sterilized mass with an inoculum and handling the same in a sterile environment; a first conditioning and reaction chamber for mixing and handling the inoculated mass in a sterile environment and controlled atmosphere of CO2 and O2, with controlled temperature and pH; a hydraulic pulper for the elementarization of the mass and its soaking up with suspensions of enzyme mixes; a hammer mill for the elementarization of vegetative material, to break up knots of stems and to pulverize leaves, detach bast from wood; a rotating tumbler having reels and counter reels for separating various fractions; a rotor compactor to reduce the volume of the vegetable mass and to remove air contained in the same; a second screw for mixing the compacted vegetetative mass with extracts containing enzymes and with water for handling in a sterile environment;

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: Chemical cellulose pulp is made from sawdust utilizing a static down-flow retention vessel. By adding steam and cooking liquor to a flow of sawdust a heated slurry, at a cooking temperature of about 250-350° F., is produced. The heated slurry is, at superatmospheric pressure, moved downwardly in the static down-flow retention vessel while cooking temperature is maintained, for a time period of about 0.5-6 (preferably 1 to 3) hours, the slurry having a consistency of about 5-30%. At superatmospheric pressure, without significant reduction in pressure from the retention vessel, the slurry is cooled to well below cooking temperature by diffusing cooling liquid through it, as in a conventional pressure diffuser. The discharge from the retention vessel is preferably substantially solely gravity action (e.g. using a discharge with single convergence and side relief).

Abstract: A comminuted cellulosic fibrous material treatment vessel assembly includes a substantially vertical vessel having a top, bottom, and outlet, and through which the material flows in a flow direction. The vessel preferably has a substantially cylindrical wall with at least one diameter-changing transition between the inlet and the outlet. A screen assembly is preferably provided at or just past the transition. The screen assembly comprises one or more annular screen surfaces diverging in the flow direction of the material, the angle of divergence being between about 0.5-10° to the vertical, and preferably substantially continuous. Providing such a screen assembly reduces the radial compression of material thereon, and increases the volume and rate of liquid that can flow through the material and be removed through the screen surface compared to a non-diverging screen surface (that is a right-cylindrical surface).

Abstract: A method and apparatus for heating cellulose pulp with steam are provided. Low-pressure (e.g. 3-5 bar (abs.)) steam is supplied into the pulp flowing as a plug flow in such a way that in the flow direction of the pulp, before supplying the low-pressure steam, the pulp is pressurized so that the pulp pressure at the point of the steam introduction is lower than the pressure of the available steam. After the steam is introduced the pulp is mixed with a pressure-raising mixer (such as a fluidizing centrifugal pump) to divide the steam evenly into the pulp and/or to equalize the temperature of the pulp.

Abstract: A method and apparatus for bleaching medium consistency pulp with ozone using at least 2 fluidizing mixers to mix ozone and carrier gas into the pulp. The method is particularly applicable when the volume of the bleaching gas is larger than the volume used in conventional ozone bleaching, e.g. 2 m3/adt.

Abstract: A method in connection with continuous cooking of chips, comprising impregnation of the chips with impregnation liquid in an impregnation vessel (3) and cooking of the impregnated chips in a digester (4), the impregnation vessel and the digester being connected to each other by means of a transfer circulation, which partly, via a feed line (25), feeds the chips from an outlet end (27) of the impregnation vessel to the top of the digester for separation of free liquid in a separator (28), and partly, via a return line (26), feeds separated liquid from the top of the digester to the outlet end of the impregnation vessel for use as transfer liquid for the impregnated chips, besides which cooking liquid is added to the chips in the top of the digester. According to the invention, as a first part, less than 100%, preferably less than 95% and more preferred less than 90% of the liquid which is separated from the chips in the transfer circulation, is recirculated to be used as transfer liquid.

Abstract: In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.

Abstract: In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.

Abstract: In the production of chemical pulp, such as kraft pulp, it is possible to reduce the amount of ancillary equipment, and/or the size of the continuous digester vessel, while achieving enhanced uniformity of treatment by avoiding “hang ups”. Instead of providing vertical counter-current flow of liquid and comminuted cellulosic fibrous material being treated in the lower half of the digester, the counter-current flow may be a cross flow, that is substantially horizontal (e.g. radial) while the flow of the chip column is vertical. Regardless of the configuration of the digester vessel, a single pump may be utilized for all of the recirculations, or only a few pumps for all of the recirculations.

Abstract: In a cellulose pulp handling vessel having a first diameter material storing or treating portion above a second diameter discharge which is at least 20% less than the first diameter, reduced compression of the material and reduced power requirements of an agitator (if used), compared to prior art constructions are provided. A first transition, preferably a substantially smooth interior surface substantially frusto-conical transition, is provided between the first and second diameters. A second single-convergent transition may be provided above the first transition. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. If desired, the transition may be moved, such as with a vibrator or oscillator. The invention is particularly suitable for pulp digesters and impregnation vessels.

Abstract: A walled passageway, having openings therein only at opposite, inlet and outlet ends thereof, has a shaft journalled therein. The shaft carries a screw thereon for moving shredded pulp through the passageway. The screw is foreshortened, having a length less than that of the passageway, and causes inlet-admitted pulp to form into a continuously moving pulp plug. The plug, albeit having some porosity, comprises a gas seal within the passageway, and inhibits any migration of downstream gas from escaping to the atmosphere via the passageway and the inlet thereof. In addition, a source of oxygen or such gas as is inert to any downstream process is controllingly admitted into the inlet to maintain an upstream pressure equal to, or greater than any downstream process pressure to insure against release of downstream gas into the atmosphere.

Abstract: Process and device for mixing fluid into a pulp suspension of cellulose-containing fiber material, in which the pulp suspension is pumped in through a pump inlet (17), brought into rotation and, at the desired reaction pressure, mixed with the said fluid while passing through a reaction sector comprising a stator shell (1), a rotor (7) which is coaxial therewith, and at least one fluid inlet (23), after which the pulp mixture leaves the reaction sector through a pulp outlet (20), in which the fluid, via the said fluid inlet (23), is supplied in the vicinity of the center of rotation of the rotating pulp suspension, where the local pressure in the pulp suspension is lower, due to the centrifugal force increasing radially outwards, than the reaction pressure prevailing at the periphery of the pulp suspension.

Abstract: A comminuted cellulosic fibrous material treatment vessel assembly includes a substantially vertical vessel having a top, bottom, and outlet, and through which the material flows in a flow direction. The vessel preferably has a substantially cylindrical wall with at least one diameter-changing transition between the inlet and the outlet. A screen assembly is preferably provided at or just past the transition. The screen assembly comprises one or more annular screen surfaces diverging in the flow direction of the material, the angle of divergence being between about 0.5-10.degree. to the vertical, and preferably substantially continuous. Providing such a screen assembly reduces the radial compression of material thereon, and increases the volume and rate of liquid that can flow through the material and be removed through the screen surface compared to a non-diverging screen surface (that is a right-cylindrical surface).

Abstract: A guide vane is provided in a pin fluffer to assist in pulp mat retention during fluffing by providing a cyclic lift component to the mat as it passes over the vane thereby also further increasing retention time obtained in the fluffer.

Abstract: A comminuted cellulosic fibrous material treatment vessel assembly includes a substantially vertical vessel having a top, bottom, and outlet, and through which the material flows in a flow direction. The vessel preferably has a substantially cylindrical wall with at least one diameter-changing transition between the inlet and the outlet. A screen assembly is preferably provided at or just past the transition. The screen assembly comprises one or more annular screen surfaces diverging in the flow direction of the material, the angle of divergence being between about 0.5-10° to the vertical, and preferably substantially continuous. Providing such a screen assembly reduces the radial compression of material thereon, and increases the volume and rate of liquid that can flow through the material and be removed through the screen surface compared to a non-diverging screen surface (that is a right-cylindrical surface).