Abstract: A method and apparatus for treating a fiber suspension to thicken or screen it. The suspension is fed to the gap between a filter surface and a counter member, and accepts flow through openings in the filter surface. Rejects continue along the filter surface to a rejects outlet. Relative movement, preferably relative rotation, is effected between the filter surface and counter member. The suspension at the filter surface is coarser and/or of higher solids concentration than the accepts. This coarser suspension is subjected to a force component by a protrusion on the counter member surface that tends to move it away from the filter surface, in a guided manner (between the protrusion and a guide plate). A second protrusion in the form of a backwardly inclined plate forces fresh suspension toward the filter surface to take the place of the suspension just moved away from the surface.

Abstract: Dynamic fluidized-bed reactor for carrying out a chemical or physical multi-component process, which said reactor comprises a preferably vertical, cooled or uncooled reactor chamber and a preferably horizontal cyclone that discharges the solid matter through the side of the separator chamber and the gases through one end or both ends of the separator chamber. The reactor further comprises a discharge pipe with no gas lock, which allows the solid matter to fall freely. In different applications, the reactor may include feed and discharge means for solid matter as well as a gas distributor grate. Exemplifying embodiments are a fire-tube boiler and a reactor for purification and cooling of hot gases.

Abstract: A pump for pumping an air containing medium includes rear vanes (11) on the propeller back plate of the pump and a back ball arranged so that a radially widening space is created between the impeller back plate and the rear wall for guiding the flow of the medium, generated by the combined effect of forces with different directions and different intensities directed at the medium in the spaces between the rear vanes, past gas discharge opening (12) in the rear wall of the pump or for retarding the flow thereby preventing the flow from entering the gas discharge opening (12).

Abstract: A gas turbine, or like device which utilizes gas and is susceptible to damage from particles greater than a predetermined size in the gas stream, is protected by providing a cyclone downstream of a particle separator. If any particles are in the gas flow downstream of the particle separator--an aberrant condition--the cyclone will remove them and pass them to a particle trap, from which the particles flow to a measuring device. If the measuring device detects a significant number of particles, then an alarm is sounded or corrective action taken. The cyclone may be a horizontal cyclone, or a flow through cyclone.

Abstract: A drum filter is characterized in that its filtrate compartments (20) comprise a bottom part (28,30) and a side surface (32), which is provided with a lip or curved portion (34) extending towards the inside of the compartment (20) from the edge of the side surface opposite the bottom part. The lip (34) prevents the filtrate from escaping from the compartment (20) back through the wire surface, when the drum filter (20) is rotated.

Abstract: In the inventive method and apparatus for the continuous discharge of water and fine particles from a suspension, particularly fibrous pulp, the pulp or suspension is thickened without forcing the removal of water through a relatively thick, uncontrollably gathered fiber mat. In the method, the suspension to be thickened is fed into a filtering chamber, the suspension is continuously mixed for equalizing consistency differences, the liquid is continuously removed from the suspension through a filter and the thickness of a fiber mat which forms on the filter surface is controlled by subjecting the mat to shear stresses. In a thickening apparatus for practicing this method, at least one of co-operating surfaces--i.e. the filtering surface (8) and its counter-surface (10)--is provided with loosening members (12) for non-mechanically limiting the thickness of a fiber mat forming on the filtering surface and thereby preventing the uncontrolled formation of such a mat on the filtering surface (8).

Abstract: A method and apparatus for gasifying or combusting solid, carbonaceous material a circulating fluidized bed reactor. Particles are separated from the product gas at least in two stages so that in the first stage, mainly coarser, so-called circulating particles are separted and returned to the reactor. In the second stage, fine carbonaceous particulates are separated from the gas and are made to agglomerate at a raised temperature. Coarser particles thus received are returned to the reactor through a return duct together with circulating particles. Adhesion of agglomerating particles to the walls of the duct is prevented preferably by leading hot particulates to the center of the duct and circulating particles to the walls of the duct.

Abstract: A centrifugal pump for pumping fiber suspensions including a centrifugal pump housing (50) defining a centrifugal pump chamber (54) having a suspension inlet and suspension outlet. Located within the pumping chamber is a centrifugal impeller (60). A vacuum pump chamber (76) defined by a front wall (112) facing the impeller and a rear wall (110) and opposite the front wall is located adjacent the centrifugal pumping chamber (54). A vacuum pump rotor (96) is mounted within the vacuum pump chamber at a distance from the front and the rear walls (112, 110). The axial distance between the vacuum pump rotor and the front and rear walls (112, 110) is adjustable to a value of less than 0.30 mm, and preferably less than about 0.20 mm.

Abstract: A centrifugal pump for pumping gas containing fiber suspensions in the pulp and paper industry includes a centrifugal pumping chamber (54); a centrifugal impeller (60) within the pumping chamber; a liquid ring vacuum pump (70) having a radially vaned vacuum pump rotor (96) therein; an intermediate wall (72) separating the pumping chamber (54) from the vacuum pump (70) which has a non-annular volume (146) therein and which provides a passageway between the centrifugal pumping chamber (54) and the vacuum (70). A conduit (71) within the intermediate wall (72) is connected to the non-annular volume (146) for introducing a liquid into at least one of the non-annular volume and the vacuum pump.

Abstract: A drum filter for thickening lime sludge in which the lime sludge is thickened on a filter layer (precoat) formed by the lime sludge on the filter periphery. The filter is provided with high pressure liquid nozzles continuously reciprocating in the longitudinal direction of the drum in such a way that, during each rotation of the drum, part of the filtering layer is continuously detached and drops into a vat containing the lime sludge.

Abstract: An apparatus is provided for ensuring that a device--such as a gas turbine--that utilizes gases and will be damaged by particles in the gases greater than the predetermined size, will not be subjected to such particles. A filter, or the like removes particles from the gases, and is connected to the gas utilization device, with a particle concentrating device disposed between the particle remover and turbine. A particle detector is associated with the particle concentrator for detecting an undesirable level of particles above the predetermined size, and an alarm or other device is activated by the particle detecting means in response to an aberrant condition. The particle concentrator comprises a first conduit extending to a branch section, and branching to a second conduit and a third conduit. The second conduit, which may be blind, is a substantial continuation of the first conduit, while the third conduit makes an angle (e.g. about 90.degree.

Abstract: An apparatus for treating a pulp suspension in a screening plant of a pulp mill wherein impurities are separated from defibered pulp by screening and/or cleaning, the cleaned pulp is thickened, the impurities are further treated in the screening plant by screening and defibering the accept fiber material for further screening and thickening and further impurities are removed from the screening plant after various screening stages, the apparatus including means for effecting one or both of the pulp screening and cleaning stages in a closed, pressurized space in the screening plant and preventing the access of air to the pulp treated by effecting the thickening stages in a pressurized state and at the initial pressure of one or both of the preceding screening and cleaning stages.

Abstract: In a boiler, particularly a recirculating fluidized bed boiler, the tubes of heat exchanger banks (panels) are connected together so that they are securely supported against sideways movement. A first heat transfer panel has a first plurality of elongated heat transfer tubes, vertically stacked one atop the other, and extending horizontally in a first dimension; and a second heat transfer panel has a second plurality of vertically stacked heat transfer tubes extending horizontally in a second dimension, perpendicular to the first dimension. The panels are supported by walls of the boiler reaction chamber. Connectors attach one of the tubes of the second bank to the first bank to stiffen the first bank against sideways movement. The connectors may be bollard or triangularly shaped lugs welded to or operatively engaging tubes of both banks, or a tube of the first bank may be bent to form a loop, with a tube of the second bank passing through the loop and engaging the bends of the bent tube.

Abstract: An apparatus for screening pulp comprises a vessel, a cylindrical screen within the vessel, a cylindrical rotor moving in the vicinity of the screen at a predetermined speed, an inlet for the unscreened pulp, an outlet for the screened pulp in the vessel. The rotor has a contour surface which is achieved by means of a plurality of protrusions of contoured shape on the surface of the rotor, for instance by welding. The protrusions are spaced and are arranged along the entire axial length of the rotor.

Abstract: A method of and an apparatus for separating gas from a gas containing suspension, generally a liquid medium, which may contain solid material, such as fibers in the pulp and paper industry. At least a portion of the suspension is first subjected to the centrifugal action of a centrifugal pump and then to further centrifugal separation of a centrifugal separator so as to divide the suspension at least once into two fractions, of which the heavier fraction containing less gas is discharged from the apparatus and the lighter fraction containing more gas is returned back to the suction side of the centrifugal pump.The apparatus is characterized in that the casing of the centrifugal pump is connected to a centrifugal separator for dividing the suspension into two fractions, the separator having a conduit for the discharge of the heavier fraction from the separator and a conduit for returning the lighter fraction to a channel leading to the suction side of the pump.

Abstract: An appratus for treating medium consistency pulp in connection with different treatment apparatuses, such as washers. According to the prior art the treatment of pulp, for example, the washing process, starts at a low consistency, approximately 1-3% so that it is necessary always to dilute pulp before washing, whereby the water consumption of the plant increases and the need of power in, for example, pumping and in the treatment generally increases. The present invention makes it possible to treat medium consistency pulp, because the feeding means is able to spread the pulp as an even layer on the perforated surface of the treating apparatus.

Abstract: A centrifugal cleaner has a cleaning quotient greater than 0.5 and a rejects by weight performance value typically of less than 5% (e.g. less than 2%) for conventional paper pulp furnish. The tangential inlet nozzle to the side wall near the top of the cleaner body has a non-circular--preferably D-shaped--inlet opening so as to provide enhanced throughput. The cleaner body side wall includes an upper portion that is conical and extends past the top nozzle, a generally cylindrical center portion which significantly increases retention time within the cleaner, and a conical bottom portion in which a bottom nozzle is operatively disposed. The bottom nozzle has a rejects opening therein with a diameter that is about 25-45% (preferbly roughly 1/3) of the internal diameter of the side wall at the opening, and is about 25-45% (preferably roughly 1/3) of the internal diameter of the top nozzle.

Abstract: The amount of N.sub.2 O emission from a fluidized bed reactor is reduced by adding a hydrogen radical providing additive (e.g. a hydrogen containing fuel such as natural gas or alcohol) to the flue gases discharged from the fluidized bed. Sufficient exygen is present in the flue gases--either by addition with the additive, or by addition of an excess to the combustion chamber--so that the additive reacts with the oxygen, typically raising the temperature of the flue gases (e.g. from about 700.degree.-900.degree. C. to about 950.degree.-1100.degree. C.) so that N.sub.2 O production is reduced about 10-90%. The additive may be injected in or just prior to a cyclone for separating particles from the flue gases, in a gas discharge immediately after the cyclone (e.g. just downstream of a heat exchanger for cooling the flue gases and flattening the velocity profile of the flue gases), just prior to a superheater of a convection section, or in a combustion chamber just prior to a gas turbine.

Abstract: A method and apparatus for treating zinc concentrates in order to recover zinc. The method includes an oxidizing and smelting stage (10) and, subsequent to the smelting stage, a fuming stage (20) in which the zinc-oxide-containing slag formed in the smelting stage is so reduced as to remove the metallic zinc with the exhaust gases (28). Part of the reduced slag is discharged during the fuming stage, another part (32) is recirculated to the smelting stage. In accordance with a preferable method, the slag is reduced in two successive fuming stages (20, 40). In an apparatus according to the invention, the slag circulation between the fuming and smelting stages is facilitated by overflows arranged in the partition walls (19) between the various stages.

Abstract: An arrangement for discharging medium consistency pulp in connection with diffeent pulp treatment devices or apparatuses, the arrangement having a mass chamber, which is arranged between a screw discharging pulp from a pulp treating apparatus and a centrifugal pump transferring the pulp further so that both the screw and the pump are substantially at the same horizontal level with the pulp treatment apparatus. Thus, the presence of a drop leg having a height of several meters is prevented, whereby the centrifugal pump has no need to pump the pulp upwards back to the height of the pulp treatment apparatus.