Abstract: The present invention relates to a process for producing pulp which is cooked under alkaline conditions and which is bleached without using chlorine-containing bleaching chemicals, in which process used cooking chemicals are recovered in a first recovery installation and used bleaching chemicals are recovered in a second recovery installation. The used cooking and bleaching chemicals can be regenerated and reused.

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: A new and improved way of continuously cooking fiber material, wherein temperatures and alkaline levels are controlled to be maintained within specific levels in different zones of the digesting process in order to optimize chemical consumption and heat-economy and at the same time achieve very good pulp properties. The digesting process includes a top separator that separates the transport liquid from the fiber material and permits the fiber material to be exposed to the cooking liquid.

Abstract: Provided is a method of treating chemical paper pulp having the steps of: adjusting the pH of the pulp to be between 1 and 6; treating the pulp with ozone to reduce the kappa number of the pulp; treating the pulp with a chelating agent after the ozone treating step without any intervening washing step between the ozone treating step and the chelating agent treating step; adjusting the pH of the pulp by adding alkali together with or after the addition of chelating agent to a pH exceeding 3; washing the pulp; and bleaching the pulp with peroxide.

Abstract: A process for bleaching pulp, in which, after fiber liberation, a first filtrate containing metals, principally in ionic form, is separated off from the pulp, and supplied downstream to the pulp flow after a bleaching stage.

Abstract: A new and improved way of continuously cooking fiber material, wherein temperatures and alkaline levels are controlled to be maintained within specific levels in different zones of the digesting process in order to optimize chemical consumption and heat-economy and at the same time achieve very good pulp properties. The digesting process includes a top separator that separates the transport liquid from the fiber material and permits the fiber material to be exposed to the cooking liquid.

Abstract: Device for the washing and dewatering a fibrous suspension, which device incorporates two hollow, circular cylindrical filter drums (1), which filter drums incorporate evacuation chambers inside the-filter drums for evacuation of fluid. The filter drums rotate in opposite directions to create a pinch (2) where at least one of the said filter drums (1) is installed in a trough (7,8) which partly encloses the outer surface (3) of the filter drum and which, in the direction of rotation of the filter drum, converges towards the outer surface of the filter drum. At least one pulp inflow chamber (4) is installed at the highest point (1) of one or both of the filter drums each equipped with a trough for the introduction of pulp between the outer surfaces (3) of the filter drum and its trough (7,8) for the formation of a fibrous web.

Abstract: Arrangement in a soda recovery boiler, comprising normal melt chutes (6) for removing molten salt from the recovery boiler (1). The recovery boiler (1) comprises an outlet (8), mounted in the wall of the recovery boiler such that it is situated lower down than the normal melt chutes (6), in which case the molten salt can be removed from the bottom of the recovery boiler substantially through the outlet (8), when the recovery boiler (1) is emptied for maintenance or the like.

Abstract: The invention relates to a process system and a method for preliminary treatment of disintegrated cellulose-containing material, preferably wood chips, prior to pulp digestion. The process system and the method according to the invention make use of a process vessel intended to function both as a so-called chip bin and as a pre-impregnation vessel. The characteristics of the invention are that a sloping steaming vessel is arranged downstream of the process vessel for the purpose of separating an excess of pre-impregnation liquid from the pre-impregnated cellulose-containing material, that the sloping steaming vessel is arranged for supplying steaming vapor which preferably has been generated by flashing of extraction liquor from a pulp digester, and that the sloping steaming vessel is connected to a chip chute communicating with a condenser for connection to a system for managing foul-smelling process gases.

Abstract: A filter and a method for filtration is based upon moving a filter surface that is caused to move through a first filtration region (FF) for separation of a prefiltrate and through a second filtration region (KF) for separation of a clear filtrate. A vacuum is applied on the filtrate side of the filtration region (KF). The filtrate region (FF) has two filtration zones (FF1 and FF2) with mutually different pressure conditions. The filtration zone FF1 has atmospheric pressure and the filtration zone FF2 has a pressure that is lower than the pressure of FF1. The pressure change between the filtration zones (FF1 and FF2) occurs in the pre-filtrate region, i.e., before the filter surface has reached the filtrate region (KF).

Abstract: A process for evaporating spent liquor or other waste liquids from cellulose cooking, The evaporation is performed in a multiplicity of evaporators which are coupled in series and in which the evaporation is driven using the liquor steam. The condensates from the steam are divided, in one of more effects, into at least two fractions with respect to purity. The parer fraction from one effect is conveyed, at a high level, into a subsequent effect in the direction of movement of the liquor, while the dirtier fraction is conveyed, at a high level or at the very top, into a preceding effect in the direction of movement of the liquor.

Abstract: A device for admixing a first fluid into a second fluid. The device has a housing with a rotationally symmetrical rotation chamber defined therein that is arranged with an inlet for the second fluid and an outlet for the mixed fluids. A distance from a center shaft of the housing to its inner wall is decreasing continuously from the inlet to the outlet. The device has rotation means for setting the second fluid in rotation along the inner wall of the rotation chamber. The device also has adding means for adding the first fluid into the vortex that is formed when the second fluid is rotating in the rotation chamber.

Abstract: In a single-vessel system for continuous cooking of kraft pulp, chips and liquor are conveyed from a high pressure feeder in a transfer line to a first end of a digester. A part of the liquor is separated from the chips that are withdrawn from an outlet defined in an upper part of the digester and conveyed in a return line to the high pressure feeder. A constituent flow of liquor is led from the return line and heated and fed via one or more inlets into the digester at a location that is downstream of the outlet for the return line.

Abstract: The present invention relates to a container for storing and discharging particulate material, in particular pulp chips. For the purpose of preventing bridge formation and making possible a simple and cost-effective design, the container is made so that a positive release is achieved in different transverse directions, after which the material is fed down towards the discharge end 2. The container 1 preferably has a rectangular cross section, with a number of container sections BS1-BS8 in succession from the infeed end 4 of the container to its discharge end 2. Two opposite sides in each container section are given a diverging deflection (5°) relative to the discharge end 2, and the other opposite sides in each container section are given a converging deflection (29°). In following container sections, converging sides change to diverging sides and vice versa, which results in the positive release of the material being achieved alternately with a 90° displacement.

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: Provided is a quench vessel having a cooling structure in which a combustion gas is forced down and through a cooling liquid a plurality of times.

Abstract: A process chamber is placed in connection with a circulating fluidized bed reactor for utilizing internal or external circulation of solid material or both in heat transfer purposes. Said process chamber is located inside the furnace of the circulating fluidized bed reactor adjacent to at least one of the furnace walls. The interior of said process chamber is provided with heat exchanger means for heat transfer from the solid material to heat transfer medium inside the heat exchanger means. The process chamber comprises a top closed barrier wall forming the roof of the process chamber, wherein the inlet of the solid material into the process chamber is arranged to the lower part of the wall of the process chamber and the outlet of the solid material out of the process chamber is arranged to the upper part of the wall of the process chamber.

Abstract: In a washing apparatus for washing cellulose pup, comprising a vertical, column-shaped washing vessel (2), and a screen unit (7) which is movable in the washing vessel, during a screening phase, at a first speed, from an upper position to a lower position, and, during a return movement, at a substantially higher speed, from the lower position to the upper position, there is a float body (30) which exerts a buoyancy force on the screen unit.

Abstract: A method and an arrangement for supplying air to a fluidized bed boiler are disclosed. In the method, the air is supplied from all comers of the fluidized bed boiler substantially parallel to two opposite walls and from the middle of said walls toward the center of the fluidized bed boiler whereby the air flows cause the formation of four vortexes in the fluidized bed boiler. The arrangement comprises nozzles that blow air jets towards each other parallel to the opposite walls of the fluidized bed boiler and nozzles in the middle of the walls arranged to blow air toward the center of the fluidized bed boiler.

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.