Abstract: The present invention relates to the thickening of pulp suspensions. A low consistency pulp suspension is fed to a pre-thickener (10) through an inlet conduit (18). A layer of thickened pulp, formed on a filter surface (22), is pushed along the filter surface by a cleaning member to the discharge end of the pre-thickener and is discharged through the outlet (20). The cleaning member comprises a rotating shaft (30), on which shaft at least one screw thread (32) is fixed so as to leave a free space between the shaft and the screw thread. Essentially non-thickened pulp is allowed to flow through the apparatus via this space.

Abstract: The present invention relates to the thickening of pulp suspensions. A low consistency pulp suspension is fed to a pre-thickener (10) through an inlet conduit (18). A layer of thickened pulp, formed on a filter surface (22), is pushed along the filter surface by a cleaning member to the discharge end of the pre-thickener and is discharged through the outlet (20). The cleaning member comprises a rotating shaft (30) on which shaft at least one screw thread (32) is fixed so as to leave a free space between the shaft and the screw thread. Essentially non-thickened pulp is allowed to flow through the apparatus via this space.

Abstract: The present invention relates to the thickening of pulp suspensions. A low consistency pulp suspension is fed to a pre-thickener (10) through an inlet conduit (18). A layer of thickened pulp, formed on a filter surface (22), is pushed along the filter surface by a cleaning member to the discharge end of the pre-thickener and is discharged through the outlet (20). The cleaning member comprises a rotating shaft (30), on which shaft at least one screw thread (32) is fixed so as to leave a free space between the shaft and the screw thread. Essentially non-thickened pulp is allowed to flow through the apparatus via this space.

Abstract: The present invention relates to a method of manufacturing a wire screen product which is especially suitable for screening fiber suspensions of the wood processing industry. It is a characteristic feature of the method according to the invention of manufacturing a wire screen product including screen wires disposed crosswire in relation to a support arranagement that includes at least one support wire, the screen wires and support wire being secured to each other such that, at the first stage, the screen wire is welded by a button spot weld to the support arrangement and, at the second stage, the screen wire is welded at another point to the same support structure.

Abstract: The present invention relates to a screen cylinder for screening fiber suspensions of the wood processing industry. The screen cylinder comprises a rotationally symmetric screen surface located on the side of the pulp to be screened, and support rings supporting the screen surface on the opposite side; the screen surface mainly comprising grooves and screen apertures in connection with the grooves, the grooves being comprised of a side surface on the upstream side, a bottom surface, and a side surface on the downstream side, characterized in that the bottom surface of the groove rises towards the side surface of the upstream side.

Abstract: A pressure screen comprises an outer housing with a pulp inlet, and accepts and rejects outlets and an advantageous mount of a stationary screen drum (screen cylinder) in the housing. The screen drum is secured at an upper end flange with bolts to an intermediate ring and supported via the intermediate ring by the housing. A rotating rotor is disposed inside the screen drum. The bottom end of the screen drum is provided with at least one groove with at least one primarily flexible material ring disposed in the groove. Cooperating substantially conical surfaces are provided in the bottom of the screen drum and a bottom intermediate ring, in which the groove is formed.

Abstract: A fiber suspension, such as an in a pulp mill, is treated in an manner which minimizes both the investment and the operating costs associated with a screening plant. A single pump has an outlet connected to a knotter and primary and secondary screening states so that the pump provides substantially the sole motive force to the pulp moving it through the knotter and screening stages. The knotter and screening stages are provided in a common housing with the knotter vertically above the screening stages, and the screening stages one above the other. A single motor may be provided to rotate rotatable elements associated with the knotter and screening stages. The knotter may be connected to a knot washer external of the housing by a valved conduit less than two meters in length, and the secondary screening stage can be connected to a tertiary screening stage exterior of the housing by a valved conduit less than two meters long.

Abstract: An apparatus for screening and thickening cellulose pulp keeps cleaner than conventional apparatus. Pulse members in accordance with the prior art are constructed so that when the capacity of the screening apparatus is increased, for example by using greater pressure differences or the cleanliness of the accept is increased by decreasing the size of the perforations or slots, a situation is created in which the screen cylinder tends to clog. The pulse member of the present screening apparatus subjects the screen cylinder or screen surface to a pulse cleaning action so that there is a minimal possibility to allow the pressure effect to "escape" past the area being cleaned. The higher the consistency of the fiber matting is or the worse the screen surface is clogged, the stronger the pulse cleaning of the screen surface.

Abstract: An apparatus for treating pulp includes an outer casing, a stationary screen surface mounted in the outer casing. A conduit introduces pulp into the interior of the screen surface. An annular space is defined between the screen surface and the casing for receiving the fraction passing through the screen surface. A feed screw is rotatably mounted in the interior of the screen surface. The feed screw extends vertically or is to some extent inclined relative to the vertical direction. The feed screw includes a shaft and pulp conveying blades. The periphery of the feed screw is provided with a nozzle conduit extending substantially parallel to the shaft and located close to the screen surface for spraying washing liquid to the screen surface. The apparatus is especially suitable for screening and/or thickening of fiber suspensions in the wood processing industry.

Abstract: An apparatus and method for treating fiber suspension is especially applicable for pulp screening in the wood processing industry, particularly for the separation of light particles from fiber suspensions. The apparatus comprises an outer casing with conduits for inlet pulp, accepts, heavier rejects and lighter rejects; a filter cylinder and a rotor, the surface of which is provided with at least one protrusion; and an opening for guiding the light rejects through the surface of the rotor.

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: The present invention provides an improved arrangement for removing thread-like impurities, such as wire rope, wire and the like, from a defiberizing drum or the like used in the defiberizing of waste paper. A ramped or inclined member, in the form of a bar or a lath, is disposed within a first or inlet portion of the drum and is secured to the drum casing wall at a predetermined distance from the partition wall that separates the first portion from a second portion of the drum. As the drum operatively rotates, a wire ball or mass forming within the first drum portion is elevated by the ramped member to a height sufficient to bring the mass into proximity with an opening defined in the partition wall, thereby directing the mass through the partition wall opening and into the second portion of the drum for further processing and/or discharge from the drum.

Abstract: Fiber suspension, such as paper pulp flowing to the headbox of a paper machine, is acted upon by apparatus which affects the axial direction and magnitude of the speed of the fiber suspension during screening to optimize results. A rotor cooperates with a screen cylinder, the rotor having a plurality of projections arranged along its axial length. The axial length of the rotor preferably has different axially extending circumferential zones. The projections have non-axial surfaces which act on the suspension to change the axial forces. Different shapes of projections are preferably provided in the different zones so that the axial forces vary in dependence upon the distance from the inlet to the screen casing, and the discharge outlet from the screen casing.

Abstract: A disc filter and method of operating same is provided in which a liquid jet is intermittently used to detach pulp cake from the disc filter. In operation, mechanical or electrical means actuate a nozzle to spray pressurized fluid at a portion of the boundary between the surface of each disc filter segment and its associated pulp cake. The nozzle is actuated to begin spraying as respective segments move into register with the nozzle and are cause to discontinue spraying prior to moving out of register when the loosened pulp cake falls from the segments by gravity. the improved control of pulp cake removal reduces use of washing fluid and results in improved pulp cake consistency.

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.