Patents Assigned to Kvaerner Pulping AB
  • Patent number: 6258282
    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).
    Type: Grant
    Filed: April 10, 2000
    Date of Patent: July 10, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Kent Strid, Rolf Oswaldson
  • Patent number: 6258206
    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.
    Type: Grant
    Filed: August 19, 1998
    Date of Patent: July 10, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Lars Gunnar Olausson, Lars Eric Pettersson, Olof Tryggve Wennberg, Anders Henrik Wernqvist
  • Patent number: 6254723
    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 A part of the liquor is separated from the chips that are withdrawn from an outlet defined in an upper part of the digester and conveyed in a return line to the high pressure feeder.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.
    Type: Grant
    Filed: December 13, 1999
    Date of Patent: July 3, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Vidar Snekkenes, Lennart Gustavsson
  • Patent number: 6254335
    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.
    Type: Grant
    Filed: October 9, 1997
    Date of Patent: July 3, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Rolf Ekholm, Ulf Jansson
  • Patent number: 6250514
    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.
    Type: Grant
    Filed: December 3, 1999
    Date of Patent: June 26, 2001
    Assignee: Kvaerner Pulping AB
    Inventor: Stefan Hansson
  • Patent number: 6241852
    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.
    Type: Grant
    Filed: January 9, 1997
    Date of Patent: June 5, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Rolf Ekholm, Ulf Jansson, Per Nyström
  • Patent number: 6238468
    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.
    Type: Grant
    Filed: March 8, 1999
    Date of Patent: May 29, 2001
    Assignee: Kvaerner Pulping AB
    Inventor: Bengt Nilsson
  • Patent number: 6233983
    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.
    Type: Grant
    Filed: September 17, 1999
    Date of Patent: May 22, 2001
    Assignee: Kvaerner Pulping AB
    Inventor: Björn Karlsson
  • Publication number: 20010000588
    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.
    Type: Application
    Filed: December 11, 2000
    Publication date: May 3, 2001
    Applicant: Kvaerner Pulping AB
    Inventor: Vidar Snekkenes
  • Patent number: 6221208
    Abstract: A method for treating a fiber pulp suspension, which comprises transporting the fiber pulp suspension from a maintenance vessel, in which there is atmospheric pressure or at most 1 bar overpressure and in which the pulp suspension is at a temperature which does not exceed 95° C., to a bleaching reactor and introducing the suspension into the bottom part of the reactor, which is at least 10 m high and at the top of which there is an overpressure which exceeds the steam saturation pressure, in which reactor the pulp is subjected to a bleaching treatment under pressure at a reaction temperature exceeding 100° C., in addition to which the pulp suspension, during the transportation from the maintenance vessel to the reactor, is heated to at least reaction temperature. The pulp suspension is pumped to a mixer with the aid of a first pump which provides 1.5-3 bar overpressure. Low-pressure steam, which is at a pressure of 3-8 bar above atmospheric pressure and a temperature of 135-155° C.
    Type: Grant
    Filed: January 23, 1998
    Date of Patent: April 24, 2001
    Assignee: Kvaerner Pulping AB
    Inventor: Håkan Damberg
  • Patent number: 6214171
    Abstract: A method in connection with continuous cooking of chips that comprises impregnating the chips with a impregnation liquid in an impregnation vessel and cooking the impregnated chips in a digester. The impregnation vessel and digester are connected to one another by means of a transfer circulation, which partly, via a feed line feeds the chips from an outlet end of the impregnation vessel to the top of the digester for separation of a free liquid in a separator. The separated liquid from the top of the digester is, partly, via a return line fed to the outlet end of the impregnation vessel for use as a transfer liqid for the impregnated chips to which cooking liquid is added to the chips at the top of the digester. Less than 100%, preferably less than 95%, and more preferred less than 90% of the liquid that is separated from the chips in the transfer circulation is recirculated to the used as transfer liquid.
    Type: Grant
    Filed: August 6, 1999
    Date of Patent: April 10, 2001
    Assignee: Kvaerner Pulping AB
    Inventor: Vidar Snekkenes
  • Patent number: 6210455
    Abstract: An evaporation apparatus for evaporation of, for example, spent liquor from pulp cooking. The apparatus has a vertical cylinder that has evaporation surfaces disposed therein. An outlet opening is defined in a widened part of the cylinder to receive driven-off steam. A skirt is disposed in the cylinder and surrounds the evaporated liquid and driven-off steam and has a diameter that is smaller than a diameter of the widened part. The skirt has an open bottom and a skirt opening is defined in a portion of the skirt that is facing away from the outlet opening.
    Type: Grant
    Filed: April 9, 1999
    Date of Patent: April 3, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Lars Olausson, Michael Thiede, Olle Wennberg, Anders Wernqvist, Martin Collander
  • Patent number: 6203662
    Abstract: This invention relates to 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, achieving very good pulp properties.
    Type: Grant
    Filed: February 17, 1998
    Date of Patent: March 20, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Vidar Snekkenes, Johan Engström, Krister Olsson, Mikael Lindström, Christofer Lindgren, Sören Gustavsson
  • Patent number: 6179958
    Abstract: A method for cooking chips, involving steaming the chips, impregnating the chips with impregnating liquid in an impregnation vessel, which impregnating liquid comprises fresh cooking liquid and spent liquor, extracting spent liquor from the impregnation vessel, cooking the impregnated chips in cooking zones including an introductory co-current cooking zone and a concluding counter-current cooking zone, extracting spent liquor from the digester at a position between the said co-current and counter-current cooking zones, transferring the said spent liquor from the digester to at least one position upstream of the digester, circulating the cooking liquid in a bottom circulation within the said counter-current cooking zone, heating the circulating cooking liquid by means of heat exchange, and supplying wash liquid to the bottom of the digester.
    Type: Grant
    Filed: July 29, 1998
    Date of Patent: January 30, 2001
    Assignee: Kvaerner Pulping AB
    Inventors: Claes Göran Lys{acute over (e)}n, Torbjörn Ulf Olsson, Gunnar Carl Wernqvist
  • Patent number: 6162408
    Abstract: Ash from a recovery boiler is purified by leaching or evaporation-crystallizing contaminants such as, chlorides and potassium salts in water. The leaching or evaporation-crystallizing takes place in an aqueous solution at a temperature that is in the vicinity of the boiling point of the aqueous solution. The leached or evaporation-crystallized ash is returned to the black liquor or to the recovery boiler while the leaching water or the evaporation-crystallization water is then cooled to less than 32.degree. C., preferably 10-15.degree. C. Sodium sulphate containing crystallization water, such as sodium sulphate heptahyfdrate or sodium sulphate decahydrate, is crystallized out and then separated to be reintroduced into the black liquor, directly into the recovery boiler or into the leaching solution or evaporation-crystallization solution.
    Type: Grant
    Filed: April 19, 1999
    Date of Patent: December 19, 2000
    Assignee: Kvaerner Pulping AB
    Inventor: Martin Wimby
  • Patent number: 6159336
    Abstract: This invention relates to 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, achieving very good pulp properties.
    Type: Grant
    Filed: October 29, 1997
    Date of Patent: December 12, 2000
    Assignee: Kvaerner Pulping AB
    Inventors: Johan Engstrom, Vidar Snekkenes, Krister Olsson, Mikael Lindstrom, Christofer Lindgren, Soren Gustavsson
  • Patent number: 6156159
    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.
    Type: Grant
    Filed: September 29, 1999
    Date of Patent: December 5, 2000
    Assignee: Kvaerner Pulping AB
    Inventors: Rolf Ekholm, Ulf Jansson, Per Nystrom
  • Patent number: 6155210
    Abstract: The invention relates to a method of firing black liquor in recovery boilers where the intention is to get fumes having a low content of nitrogen oxides (NO.sub.x). The invention is characterized in that a part of the combustion air is added as a last portion at a level on a very high level so that a reducing atmosphere will exist in a very great part of the boiler and during a long period of time of at least 3-5 seconds. The invention also includes a recovery boiler for carrying out the above said method.
    Type: Grant
    Filed: July 19, 1999
    Date of Patent: December 5, 2000
    Assignee: Kvaerner Pulping AB
    Inventor: Nils Gustav Lindman
  • Patent number: 6143130
    Abstract: A method for impregnation and chemical digestion of lignocellulosic material and recovery of pulping liquors. A spent impregnating or cooking liquor is withdrawn and sulphurous compounds are recovered therefrom in a partial oxidation reactor. These sulphurous compounds are converted into hot liquid elemental sulphur which thereafter is mixed with a hot sulphide containing liquor to provide a polysulphide liquor with a concentration greater than 10 g/l and which is essentially free from thiosulphate. This polysulphide liquor is used for carbohydrate stabilising impregnation and/or for cooking at a relatively low temperature.
    Type: Grant
    Filed: December 17, 1997
    Date of Patent: November 7, 2000
    Assignee: Kvaerner Pulping AB
    Inventors: Lars Stigsson, Mikael Linstrom
  • Patent number: 6139685
    Abstract: The present invention relates to a method for treating a pulp suspension in which the suspension is rotated in a rotationally symmetrical, rapidly rotating and permeable screen basket so that the suspension is subjected to the influence of a centrifugal force and dewatered at the same time as the suspension is conveyed by a rotating screw along the inner wall of the screen basket. The invention is characterized in that the suspension is caused to rotate by means which are arranged at the entrance to the screen basket, and in that the outer edges of the said screw bear against or are immediately adjacent to the screen basket and rotate at a higher speed than does the screen basket so that the screw scrapes the inner wall of the screen basket.
    Type: Grant
    Filed: May 13, 1999
    Date of Patent: October 31, 2000
    Assignee: Kvaerner Pulping AB
    Inventor: Kuniaki Saito