Abstract: A de-trashing unit has a rotor fabricated from steel blank. The rotor has two swept blades with blunt leading edges and relieved trailing edges. The rotor is driven to rotate over a trash screen with holes of between one-quarter and one-half inch in diameter. The blade is positioned with a clearance between the blade and the screen of between 0.005 and 0.010 inches. The relieved portions of the blades face the screen while the trailing edges of the blade are tapered between 18 and 30 degrees away from the screen surface. The blade taper creates a strong negative pressure pulse which keeps the screen clear. Holes drilled through the relieved portion of the blade allow circulation through the blade into the region of low pressure generated by the relieved portions passing over the screen. The circulation created by the holes creates microturbulence which keeps a water and paper fiber slurry fluidized.

Abstract: A rectangular clarifying tank has an inclined beach formed of sheet metal and having 575 holes per square inch, each hole having a diameter of 20 thousandths of an inch. Two side chain drives advance several scrapers along the beach. Each scraper has a rotatable knurled pipe which turns the sludge and aids dewatering through the beach. The sludge removed from the clarifier has a solids content of between eight and twelve percent. Additional dewatering may be accomplished by applying a vacuum to the last one-quarter of the beach. A tray positioned beneath the beach collects water which drains through the beach. The drain water may be returned to the clarifier tank or may be directly treated as clarified water.

Abstract: A plurality of like wedge bars are formed with a groove between two lands. The wedge bars are assembled into a cylindrical screen, with the grooves defining screening slots of a uniform width. The wedge bars may be electron beam welded or furnace brazed to support rings. Alternatively, the wedge bars may be held in place by slots in support rings and circumferential clamping applied by jack wedge assemblies. Multiple cylindrical segments may be connected together into a single screen cylinder by an ear and slot arrangement. The screen cylinder so formed may have slots of 0.004 inches or less in width, and may be formed of a wide range of wear and corrosion resistant materials.

Abstract: A pressurized dynamic pulp washer including an annular hollow housing in which the stock is driven axially along a plurality of stationary, annular, coaxial wash filters in axially reversible directions, with an annular rotatable shell between the wash filters to urge liquid through openings in the filters, to generate axial, radial and circumferential velocities in the slurry to create localized pulses in the slurry to urge liquid through the filters with wash liquid being introduced to replace liquid filtered from the fibers in the slurry.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.

Abstract: An improved screen plate for a pressure screening apparatus and a method for making the basket are disclosed wherein prestressed areas are provided at each end of each slot formed in the screen plate for minimizing crack propagation.

Abstract: An improved efficiency screen plate for screening pulp in a pressure screening apparatus is disclosed wherein various design parameters are established which increase screen performance, particularly in screening medium consistency pulp. The basket is formed of thin, sheet-like material formed without machining into an undulating pattern. Undulation frequencies, slot location, turbulence bar frequency, and turbulence bar height are established for increasing screen performance.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.