Patents Assigned to A. Ahlstrom Corporation
  • Patent number: 4919158
    Abstract: The present invention relates to a method and an apparatus for washing pulp according to which method the pulp is supplied onto a movable liquid-pervious support surface (2) to form a substantially continuous layer (7); and washing liquid is supplied to the pulp layer and passed in several successive washing phases through different areas of the layer in such a way that the washing liquid gradually flows in the opposite direction compared with the flow direction of the pulp layer. According to the invention the washing liquid is divided in two or more partial flows which pass alternately through different washing phases in such a way that the washing liquid which in one phase has passed through the pulp layer flows past at least the washing phase preceding it in the flow direction of the pulp layer. The apparatus of the invention preferably comprises a rotating cylinder (1) the casting surface (2) of which serves as the liquid-pervious support surface for the pulp.
    Type: Grant
    Filed: March 20, 1987
    Date of Patent: April 24, 1990
    Assignee: A. Ahlstrom Corporation
    Inventors: Seppo K. Kokkonen, Harri T. Qvintus
  • Patent number: 4919796
    Abstract: A method and apparatus allow the efficient grading of a fiber suspension (e.g. paper pulp) having a consistency of 0.5% or more. A cyclone separator has its rejects outlet connected to a rejects chamber with a solid confining surface. A rotor is mounted for rotation in the rejects chamber adjacent its discharge opening, and accelerates the rotational speed of suspension flowing into the rejects chamber to continue the grading action of the cyclone. Accepts that are discharged from the rejects chamber are recirculated to the inlet to the cyclone separator, while the rejects are passed out for disposal or other action. Vertically extending ribs may be provided along the solid interior walls of the rejects chamber, which act with the rotor to efficiently break up fiber flocks in the suspension.
    Type: Grant
    Filed: August 23, 1988
    Date of Patent: April 24, 1990
    Assignee: A. Ahlstrom Corporation
    Inventor: Pentti A. Vikio
  • Patent number: 4918807
    Abstract: A plurality of blind openings (e.g. holes or slots) are formed through a first face of a steel plate and extend a predetermined distance short of the opposite face. Larger size openings are formed through the first face using the blind openings as pilot openings. The larger size openings extend into the plate short of the terminations of the blind openings. Metal is machined from the opposite face in parallel rows defining grooves and to a depth to uncover the terminations of the blind openings in the plate body thereby providing through-extending screen openings in the plate. The ridges (bars) between the grooves may be quadrate in cross-section, or a side face sloped (angled) by machining. A screen cylinder with bars of the invention has a maximum screen area (compared to prior art screens with bars).
    Type: Grant
    Filed: October 19, 1988
    Date of Patent: April 24, 1990
    Assignee: A. Ahlstrom Corporation
    Inventor: Frey A. Frejborg
  • Patent number: 4915822
    Abstract: A method and an apparatus for treating a fiber suspension wherein the fiber suspension is fed into a treatment apparatus having treatment zones and divided into two fractions, an accept and a reject, the reject being guided from one zone behind at least one adjacent treatment zone to a separate reject treatment zone, in which the remaining accept of the suspension is discharged. The apparatus being divided into a plurality of axial zones and having a rotor and at least one screen arranged in an outer housing, and in the treatment space between the screen and the rotor, members are arranged for guiding the suspension from the different treatment zones of the treatment space to the separate reject treatment zone.
    Type: Grant
    Filed: October 2, 1988
    Date of Patent: April 10, 1990
    Assignee: A. Ahlstrom Corporation
    Inventor: Risto A. Ljokkoi
  • Patent number: 4909899
    Abstract: A method of concentrating sludges wherein liquor is heated under pressure indirectly with flue gases from the combustion of previously concentrated sludge, after which the sludge is caused to expand or subjected to reduced pressure which results in evaporation of water and concentration of the sludge to a dry-substance content of over 55%.
    Type: Grant
    Filed: September 21, 1987
    Date of Patent: March 20, 1990
    Assignee: A. Ahlstrom Corporation
    Inventor: Erkki J. Kiiskila
  • Patent number: 4904395
    Abstract: The present invention relates to a method and an apparatus for thickening of fiber suspension. In particular, the invention relates to removal of water from pulp which is caused to thicken in a closed space equipped with a fine-perforated or fine-slotted screen surface. The problem with the prior art devices has been their complex structure or, in simpler solutions, their great susceptibility to clogging. These problems have been found out to be overcome through dimensioning of perforations in the screen surfaces (28, 30; 38, 40) of the thickener and the flow channels (33; 37) between the filtering surfaces (28, 30; 38, 40) in such a way that the pulp flows in the channels as a plug flow, that is, the internal friction of the pulp is greater than the surface friction between the pulp and the screen surface.
    Type: Grant
    Filed: December 9, 1987
    Date of Patent: February 27, 1990
    Assignee: A. Ahlstrom Corporation
    Inventor: Kaj O. Henricson
  • Patent number: 4900516
    Abstract: A circulating fluidized bed reactor having a reactor chamber for containing fluidizing gas having entrained therein particulate material; a horizontal cyclone having a circumferential wall defining a separator chamber operatively connected at the reactor chamber for separating the material from the gas; a return pipe connected at the separator chamber of the cyclone at the circumference thereof for returning the separated material from the separator chamber to the reactor; and means for discharging the purified gas located in at least one end of the separator chamber of the cyclone. Preferably the separator chamber is located above the reactor chamber and the return pipe is connected at the lowermost point of the circumference of the separator chamber. The reactor is useful as combustor, gasifier and for the carrying out of chemical process.
    Type: Grant
    Filed: September 15, 1986
    Date of Patent: February 13, 1990
    Assignee: A. Ahlstrom Corporation
    Inventors: Folke Engstrom, Seppo Ruottu
  • Patent number: 4884516
    Abstract: An inclined grate construction or apparatus in the combustion chamber of a combustion furnace, comprising a plurality of adjacent grate tubes in the longitudinal direction of the grate, said tubes being welded together through flat bars. Below the grate is disposed a grate bar carriage, which, in use, reciprocates horizontally respective to the grate. The grate bar carriage supports at least one grate bar, which is pushed through the grate via an opening in the flat bar between two adjacent grate tubes when the grate bar carriage moves towards the grate. The grate bar carriage is also vertically displaceable.
    Type: Grant
    Filed: November 30, 1988
    Date of Patent: December 5, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Lauri G. Linsen
  • Patent number: 4884943
    Abstract: A method and an apparatus for treating high-consistency fiber suspension are especially suitable for short distance conveyances of thick fiber suspensions (consistency more than 15%) in pulp and paper industry, for example for discharge of mass towers either with or without any actual pump. The treatment of fiber suspension with a consistency more than 15% is not possible with the known technique without a displacement type of pump, which is expensive and easy to break. Additionally, in discharging of the mass tower, drop leg, etc., fiber suspension causes trouble by arching in the container in such a way that it forms an open chamber around the pump located at the bottom of the container which chamber is slowly filled by fiber suspension. The problems are solved or minimized by arranging a feed apparatus (31) in the pump chamber, which feeds fiber suspension to a fluidizing rotor (21), for fluidizing the fiber suspension, whereafter the suspension flows onwards.
    Type: Grant
    Filed: June 21, 1988
    Date of Patent: December 5, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Toivo Niskanen
  • Patent number: 4880540
    Abstract: The pulp screening apparatus comprises a housing having an inlet for allowing fibrous stock to be introduced into the interior, a first outlet for allowing the accept screened stock to be removed, a second outlet for the reject, a screen having a contour surface within the housing, a rotor moving in the vicinity of the screen at a predetermined speed and forming together with the screen an annular screening chamber. The rotor has at least the surface facing the screen partially contoured and is provided with a plurality of perforations along at least a portion of the length of the screening chamber to allow fibrous stock to be introduced into the screening chamber and to prevent the undesired debris of the stock from entering the chamber. Both sides of the rotor may have a contoured surface with grooves.
    Type: Grant
    Filed: June 11, 1987
    Date of Patent: November 14, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Frey Frejborg
  • Patent number: 4877368
    Abstract: A fluidizing centrifugal pump for medium to high consistency fiber suspension includes a housing having an inlet channel and an outlet and an impeller operatively rotatable about the pump axis. The impeller has a working vane and at least a blade extending substantially axially from the working vane and disposed in the inlet channel for fluidizing suspension which is received in the pump inlet. A feeding vane, preferably in the form of a spiral thread, is disposed in the inlet channel, radially-outwardly from the fluidizing blade and extending along at least a portion of the axial extension of the blade.
    Type: Grant
    Filed: November 8, 1988
    Date of Patent: October 31, 1989
    Assignee: A. Ahlstrom Corporation
    Inventors: Jukka Timperi, Reijo Vesala, Vesa Vikman
  • Patent number: 4871459
    Abstract: A filter bed clarifier comprising a tank (1), which consists of an upper, cylindrical part (2) and a lower, tapered part (3) and which is provided with a centrally disposed feed pipe (11) for the liquid to be clarified. The feed pipe has an outlet leading into the tank at the top opening (7) of the circulating/mixing cone (6) disposed in the lower, tapered part of the tank. The top opening is larger than the outlet opening (12) of the feed pipe so that the sludge being discharged from the feed pipe draws sediment flocs from the lower part of the bed, thus causing internal circulation of the sediment. The apparatus is especially suitable for clarifying green liquor.
    Type: Grant
    Filed: September 8, 1988
    Date of Patent: October 3, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Juha S. Titoff
  • Patent number: 4869207
    Abstract: A circulating fluidized bed reactor includes a filter apparatus for separation and recycling of fine particles which are entrained by the flue gas. The housing of the filter apparatus has a plurality of vertically disposed ceramic filtration tubes. The reactor chamber and filter housing are arranged back-to-back and have a common wall therebetween. A pre-separator for separation of coarse particles is provided which connects the reactor chamber with the filter apparatus. The reactor, the separator and the filter apparatus are encased in a pressure-proof cylindrical vessel. The walls of the reactor chamber and the filter housing can be water-cooled. In another form, the filter is comprised of a plurality of porous plates having ribs abutting adjacent plates to define passageways through the filter.
    Type: Grant
    Filed: April 11, 1988
    Date of Patent: September 26, 1989
    Assignee: A. Ahlstrom Corporation
    Inventors: Folke Engstrom, Juhani Isaksson
  • Patent number: 4864944
    Abstract: A fluidized bed reactor (1) comprising a reactor chamber (4) having a gas distributor plate (5) for feeding primary air, and space above said distributor plate (5) is divided into compartments (6) by means of partition walls (7) having discharge openings (9) for feeding secondary air to the circulating bed.
    Type: Grant
    Filed: June 23, 1988
    Date of Patent: September 12, 1989
    Assignee: A. Ahlstrom Corporation
    Inventors: Folke Engstrom, Juhani M. Isaksson, Reijo Kuivalainen
  • Patent number: 4863353
    Abstract: An arrangement for attaching a machine element to a shaft, especially for impellers of pumps, comprises a spiral-formed key which is firmly fixed to the shaft, with the element to be attached being provided with a corresponding keyway.
    Type: Grant
    Filed: November 17, 1987
    Date of Patent: September 5, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Heikki Manninen
  • Patent number: 4854819
    Abstract: A method and a device for pumping fibre suspensions of high consistency are described. Shear forces disrupting fibre flocs are induced in the front of the impeller in a centrifugal pump which fluidize the fibre suspension thus converting it into an easily pumpable state. This is effected by an inlet part of the pump having recesses and/or lobes in its inner surface in front of the impeller which cooperate with a rotor having an outer surface in which there are lobes. The rotor is disposed into the outlet part of the vessel during operation.
    Type: Grant
    Filed: December 10, 1987
    Date of Patent: August 8, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Johan Gullichsen
  • Patent number: 4842688
    Abstract: A method of removing macromolecular organic dissolved and colloidal compounds from the effluents of a paper and cellulose mill by using waste sludge containing fibers and chemicals. The sludge is acidified to a pH of approx. 2 by a mineral acid prior to adding into the effluent. Organic material is precipitated with fibers in a sedimentation vessel at a pH of 4.5-6.
    Type: Grant
    Filed: November 18, 1987
    Date of Patent: June 27, 1989
    Assignee: A. Ahlstrom Corporation
    Inventors: Johan Gullichsen, Pertti Hynninen
  • Patent number: 4841884
    Abstract: In a fluidized bed reactor, nozzles are provided for distributing fluidizing gas from a windbox into the reactor while preventing the backflow of solid particles through the nozzle into the windbox. The nozzle defines an upper part of high heat and wear resistant material adapted to contact the mass of particles. At least one opening is defined in each nozzle through which fluidizing gas passes between the upper part and the windbox, and a solid, though porous, material abuts or defines the opening for allowing the passage of gas while preventing passage of solid particles. The nozzle may comprise a stand pipe having a sintered metal portion disposed below the upper part. Other constructions provide the solid mass as a metal wire mesh acid proof filter, or as a porous ceramic material, or as a high temperature ceramic material. The solid mass may have pores with a pore size of between about 50-1,000 micormeters.
    Type: Grant
    Filed: May 26, 1988
    Date of Patent: June 27, 1989
    Assignee: A. Ahlstrom Corporation
    Inventors: Folke Engstrom, Reijo Kuivalainen
  • Patent number: 4836915
    Abstract: An apparatus for screening paper stock comprises a vessel, a cylindrical screen cylinder within the vessel, a rotating element moving in the vicinity of the screen cylinder at a predetermined speed, an inlet for unscreened stock, an outlet for the screened stock, and an outlet for the stock fibers and unwanted rejectable material which does not pass through the screen cylinder. The rotating element has a contour surface with grooves formed of a first bottom plane parallel the envelope surface, an inclined plane, an upper plane, and a side plane, the side plane being essentially perpendicular to the first plane, the inclined plane forming an angle between 5.degree.-60.degree. with the first plane, the upper plane being parallel to the first plane. The rotor element may be either a rotor or blade type segments. Also the screen cylinder has a contour surface. The inclined plane of the contour surface of the rotor may be the upstream or the downstream side plane. The method is also described.
    Type: Grant
    Filed: June 26, 1987
    Date of Patent: June 6, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Frey Frejborg
  • Patent number: 4834547
    Abstract: The invention relates to an apparatus for mixing chemicals in fibre suspensions. The apparatus comprises a rotor (8) provided with blades and mounted to rotate in a casing (1) having an inlet (3) and an outlet (5) for the fibre suspension; and an inlet or inlets (6) for chemicals. The rotor (8) comprises a fluidizing and gas separating section (9), a pumping section (10) and a section (12) for mixing chemicals. An inlet (25) for chemicals leads to a space (24) between the pumping section (10) and the mixing section (12). The blades of the mixing section preferably cooperate with the casing wall (17) provided with ribs (18).
    Type: Grant
    Filed: March 10, 1987
    Date of Patent: May 30, 1989
    Assignee: A. Ahlstrom Corporation
    Inventor: Toivo Niskanen