Abstract: The present disclosure relates to producing paper or paperboard having improved stiffness and strength, compared to the conventional paperboard at the same basis weight. It also discloses a method of wood pulping having a significantly increased yield and providing fiber pulps with enhanced properties such as strength and stiffness. Wood chips are chemically pulped to a high kappa number, providing a rejects component and an accepts component. The rejects component is subjected to a substantially mechanical pulping process, optionally in a presence of bleaching agent, prior to blending back into the accepts component. The resulting fiber blend is washed, optionally bleached, and subjected to a papermaking process to provide paper or paperboard with enhanced strength and stiffness at low basis weight.

Abstract: A dynamic mixer for a plurality of fluid components contains a housing and a rotor element which is rotatably arranged in the housing, with the housing having an inlet opening for at least one respective component and having at least one outlet opening. A ring-shaped intermediate space is provided between the rotor element and the housing in which a mixing element connected to the rotor element is arranged. The mixing element has a vane element which is formed as a directing element for conveying the components from the inlet opening to the outlet opening. The vane element is a directing element and has a directing surface which has a concave curvature with respect to the outlet opening and is further remote from the outlet opening at the onflow side than at the outflow side.

Abstract: One embodiment provides an apparatus for cooking lignocellulosic material, comprising a pressurizable, inclined top separator including a sluicing liquor inlet for receiving a sluicing mixture comprising impregnated lignocellulosic material and sluicing liquor, a hot black liquor inlet, an excess liquor outlet, and an impregnated lignocellulosic material outlet; a continuous digester vessel including an impregnated lignocellulosic material inlet in communication with the impregnated lignocellulosic material outlet, and a warm black liquor outlet; and a black liquor circulation and heating loop including a warm black liquor inlet in communication with said warm black liquor outlet, a heater for heating warm black liquor to produce hot black liquor, and a hot black liquor outlet in communication with said hot black liquor inlet. Methods of making and using the apparatus are also provided.

Abstract: The method and arrangement is for the feed of a chips suspension from one vessel to a subsequent digester in a continuous cooking process for the production of chemical cellulose pulp. The vessel has an inlet defined therein for the input of chips and an outlet defined therein for the output of a chips suspension. The chips suspension in the vessel has a first fluid/wood ratio established above a second fluid/wood ratio that is established at the bottom of the vessel. The second fluid/wood ratio is at least as great as, preferably greater than, the first fluid/wood ratio. After the output of the chips suspension from the vessel and before the chips suspension is placed under pressure for onwards transport to a subsequent digester, a fraction of fluid is withdrawn from the chips suspension, whereby a third fluid/wood ratio is established in the chips suspension.

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: 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 system for treating pulp comprises a dewatering device (2) for dewatering the pulp to a fiber concentration of at least 20%, a closed pulp-shredding vessel (16) for shredding the dewatered pulp, and an outlet pipe (22) from the pulp-shredding vessel. A transport screw (18) is arranged in the outlet pipe for transporting the shredded pulp from the pulp-shredding vessel through the outlet pipe through a reactor vessel (6) for bleaching the shredded pulp through reaction with ozone gas. The outlet pipe (22) is designed with a heightened roof portion (27), so that an upper gas space (29) free from pulp is formed in the outlet pipe between the roof portion and the transport screw. A flow-restraining member in the form of a partition wall (31) is arranged in the upper gas space in the outlet pipe for restraining the gas flow through the gas space, whereby the pumping action of the transport screw in the outlet pipe is decreased.

Abstract: The invention relates to a feed arrangement for feeding chips to chip bins (1) in the production of cellulose pulp in continuous digesters (16), in which the chip bin is constituted by a treatment vessel having a top and a bottom, in which the chips are fed into the top (13) of the treatment vessel and fed out via the bottom of the treatment vessel using suitable lock members (10, 11). Distribution devices (4a, 4b) for the addition of steam are disposed in the treatment vessel so as to heat the chips to a level above 80° C., preferably around 100° C., when the chips are fed out via the bottom of the treatment vessel. By virtue of the fact that the chips are fed into the treatment vessel via at least one liquid lock (30) and the treatment vessel is otherwise sealed off, the quantity of driven-off gases from the chip bin is reduced to a minimum, at the same time as an effective utilization of available energy is obtained.

Abstract: Methods and systems for the treatment of pulp are provided. The methods include dewatering pulp to a fiber concentration of at least 20%, shredding the dewatered pulp in a closed pulp shredding vessel, transporting the shredded pulp without compression continuously out of the pulp shredding vessel through an outlet pipe which is kept completely filled with passing pulp, directly transporting the shredded pulp to a reaction vessel through a gas-tight conduit gas sealed from the surroundings and communicating with the outlet pipe and the reaction vessel, bleaching the shredded pulp in the reaction vessel with ozone gas, and regulating the gas pressure in the pulp shredding vessel and in the reaction vessel so that ozone gas is prevented from leaking upstream through the outlet pipe.

Abstract: A method and an apparatus for adjusting a chemical dosage of a pulp processing stage. The method comprises measuring a change in a variable in dependence on the chemical dosage and the chemical dosage to be added, and determining a model describing the change in the variable as a function of the chemical dosage. A performance index is determined for the new model to be compared with the performance index of certain previously determined models. The model that produced the best performance index is put to use.

Abstract: Containers for collecting and discharging particulate lignocellulosic material are disclosed, including a cylindrical upper portion, a lower portion tapering towards a bottom elongated space, an exit pipe below the bottom, a pair of parallel screws mounted on parallel shafts in the elongated space in a common horizontal plane for feeding the particulate lignocellulosic material towards the exit pipe, a pair of distributors disposed on the parallel screws above the exit pipe comprising radial discs, and a pump below the exit pipe for transporting the particulate lignocellulosic material to a subsequent step.

Abstract: A continuous, alkaline process for the production of pulp from wood chips, wherein the preheated chips are subjected to an extended impregnation step for at least 60 min, preferably longer, at a temperature not exceeding the impregnation liquor boiling point at atmospheric conditions, and a rapid heating and cooking period of less than 65 min, preferably shorter, followed by cooling to below reaction temperature. Fresh alkali is added both during impregnation and the heating/cooking period.

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

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

Abstract: Process 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 feeding system for feeding comminuted cellulose containing material and liquid to a continuously operating treatment vessel. The feeding system comprises a chute, operating at a first pressure, a high pressure feeder sluices the material to a second pressure, that is higher than the first pressure, for further conveyance to the treatment vessel. The high pressure feeder also receives a return liquid flow from the treatment vessel at the second pressure and recirculates a recirculation flow to the chute. The high pressure feeder is in fluid communications, regarding both the liquid and the material, with the recirculation flow when any of the pockets of the high pressure feeder is in a location which corresponds to an outlet for the recirculation flow.

Abstract: A process and apparatus for treating and particularly bleaching pulp contacts a pulp with a gaseous reaction medium in a reactor tower. The pulp is fluffed and refined before being added to the pulp bed and then homogeneously permeated with the gaseous reaction medium to produce a uniformly treated pulp. A distribution device is included in the reactor to uniformly distribute the pulp in the reactor and form a homogenous pulp bed having a substantially even upper surface uniform bed depth.

Abstract: A continuous pulp digesting apparatus where wood chips and a cooking liquor are directed into a first cooking zone, and a portion of the cooking liquor is extracted at an intermediate region downstream, of said first cooking zone. Fresh liquor is introduced into said intermediate region to adjust pH level to inhibit scaling and/or clogging of strainers in the digester, and further digesting is accomplished in a second cooking zone downstream of an intermediate region. Liquor is extracted through strainers at a lower location of said second cooking zone.

Abstract: An inert gas such as helium is employed as a tracer gas in a pulp and paper mill to determine the utilization of oxygen by an aqueous cellulosic pulp particularly, as well as other parameters, in an oxygen delignification or extraction in which oxygen is dissolved in the pulp and reacted to solubilize lignins and reduce the requirement for chlorine-based bleaching chemicals.

Abstract: The present invention provides a reactor adapted to simultaneously accomplish chemical reactions and operations of size reduction of the solid materials in suspension and particularly for treatment in the cellulose and/or paper pulp industry. The reactor provides an essentially closed working environment and is provided in the lower part with a rotor which creates turbulence with flows over essentially the whole volume of the closed environment and is adapted to realize said conditions of the size reduction of solid materials with intimate mixing of same with the suspending liquid.

Abstract: A method and apparatus for the delignification of cellulosic fiber material to minimize the amount of reject material in the final pulp produced. The fiber material is digested, washed, oxygen delignified, and passed through a screening stage to provide a main pulp stream, and a reject stream from the separation stage. The flow and consistency of the separated reject material is determined, the reject material is refined, and sufficient chemical is added to the separated reject material, based upon the flow and consistency thereof, so that subsequent delignification of the reject material may be effected. This may be accomplished either by passing the reject material through a separate oxygen delignification stage and then returning it to the main pulp stream, or adding caustic to it and soaking it in a soak tank for predetermined period of time, and then returning it to the main pulp stream before the oxygen delignification stage therein.

Abstract: Wood pulp is bleached with chlorine dioxide gas. The gas is obtained by feeding a chlorine dioxide solution to a stripper. Shredded or fluffed pulp is exposed to a controlled amount of chlorine dioxide gas for a time period sufficient to obtain the required pulp brightness. The amount of unused chlorine dioxide gas is continuously monitored. The controlled amount of chlorine dioxide gas fed to the bleaching system is automatically adjusted by controlling the amount of chlorine dioxide solution fed to the stripper in response to changes in the amount of unused chlorine doxide gas leaving the bleaching system. Unreacted gases are recycled back to the stripper in response to the concentration of chlorine dioxide gas conducted from the stripper to the reaction area.

Abstract: In the continuous production of paper pulp from ligno-cellulose raw material, the raw material is subjected to grinding and/or delignification by passing it in the form of small pieces between interpenetrating helicoidal surfaces driven synchronously in rotation inside a casing. The pitch of the helicoidal surfaces is arranged to provide at least one supply zone in which the material is driven downstream by rotation of the surfaces and at least one braking zone in which the material is braked.

Abstract: In an illustrated embodiment, brightness, color, opacity and fluorescent contribution to brightness are measured by an on-line sensing head providing for simultaneous measurement of transmitted and reflected light. The instrument is designed so as to be capable of transverse scanning of a moving paper web on the paper machine. An optical window member serves as a backing for the web for reflectance measurements and is in series with the web with respect to transmittance measurements. The optical window itself is selected as to its reflectance and transmittance so as to provide for periodic standardization of the instrument in an off-sheet position.

Abstract: Apparatus for producing pulp for use in the manufacture of kraft type products such as linerboard and bag grade paper comprising means for steaming small segments of fibrous material and defiberizing the same in a pressurized atmosphere and at an elevated temperature, means for mixing the defiberized material, while still hot, with hot kraft pulp and means connected to receive and then refine the mixture so obtained.

Abstract: Gaseous reaction apparatus wherein a portion of the supplied gas is discharged from the reaction vessel at a location below the upper level of a therein contained columnar mass of material wherein the gas is discharged into a receiving chamber extending along the outer periphery of the vessel and open to the lower portion of the vessel through an unrestricted opening being free from screens and filters, and such discharged portion of the gas, with or without cooling, is recirculated back into the upper inlet end of the vessel, thereby controlling the temperature in the vessel by removing or redistributing heat therein. Such apparatus is particularly useful in the gas phase treatment of fibrous material such as the bleaching or delignification of lignin-containing cellulose pulp.