Abstract: Hydrocyclone cleaning systems and methods remove contaminants from a suspension of papermaking stock. A subsystem 10 employs forward cleaners for removing heavy contaminants while a subsystem 12 is fed directly from subsystem 10 and removes lightweight contaminants. The subsystem 12 also includes a through-flow cleaner which receives the rejects flow from a primary reverse flow cleaner and both systems are connected to a common surge tank arrangement. Both subsystems operate at low consistencies or high efficiency while the primary through-flow cleaner of subsystem 12 provides a system output having a consistency approximately twice as high as that of the input so that the overall operation operates both as a stock cleaner and a stock thickener.

Abstract: A reverse hydrocyclone cleaner (10) for the centrifugal separation of lightweight contaminants contained in a suspension of papermaking fibers is formed with an elongated hollow body (12) of circular cross section which converges uniformly from a first inlet end to a second apex end, in which the ratio of the length of the conical body to its largest diameter is at least approximately 20 to 1 and defines an included angle of less than 3 degrees.

Abstract: A hydrocyclone for separating lightweight contaminants from a suspension of papermakers'stock as a through-flow design in which an inlet section has a frusto-conical flow controlling wall and has a central flow stabilizer and a tangential inlet. The flow stabilizer has a paraboloid shape and defines with the flow control wall an annular flow space of constant area along the axial length of the flow stabilizer so that fluid entering a tangential inlet at the base of the paraboloid is caused to rotate about the flow stabilizer and is delivered to the interior of the hydrocyclone without a substantial change in axial velocity.

Abstract: In apparatus for thickening a suspension of pulp material which includes an endless foraminous belt wrapping two spaced horizontally supported rolls, a special doctor mechanism is provided for transferring thickened pulp from the bare surface of the second roll into a trough mounted in the space bounded by the two rolls and the upper and lower runs of the belt. More specifically, the doctor mechanism includes a rigid doctor blade mounted with its working edge in close but spaced relation with the bare surface of the roll to remove pulp therefrom without contact with the roll surface. Provision is also made for periodically oscillating the blade about a horizontal axis to move its working edge away from and back to its closely spaced working relation with the roll.