Ingersoll-rand Company

Beloit Technologies, Inc.

Douglas L Young

Antoine G Abdulmassih

Donald B Johnson

Brian James Gallagher

Ian J Clarke-Pounder

Oscar Luthi

A support structure for thin screenplates utilized for fine screens in Fibresaving applications for pulp fiber suspensions or the like wherein a support structure having a screen support in minimum screen contact positioned by a support reinforcement and positioning device, assembled to form an integral structure which reduces the stresses and deflections in the thin screenplates occurring in operation.

Fibresaver screen basket support

A screen aperture blinding prevention and liquid overflow prevention and level control apparatus for a knot drainer senses liquid level within the knot drainer and compares the sensed level to a setpoint level. Differences in the two levels generate control signals of appropriate magnitude and direction, and those control signals are transmitted to a valve whose degree of responsiveness and openness is adjusted to change the outflow rate of accepts liquor from the accepts chamber of the rejects separator. In addition, passive level control is provided in the discharge line for establishing accept flooded screen apertures regardless of variations of inflow and outflow rates during operation while active level control to create accept flow rate greater than, less than, or equal to inlet flow rate is provided by the combination of siphonic loop, barometric leg and control values for accepts outflow and for backwash nozzle flow. Continuous flow of fiber and liquid through separating screen apertures is appropriately supervised by monitoring accepts chamber pressure.

Apparatus for controlling liquid level in a knot drainer

A hydrodynamic device for generating negative pressure excursions in a pulp slurry during fine screening, includes a plurality of half-foil members disposed on a substantially cylindrical outer surface of a rotor. The rotor is mounted within and co-axial with a substantially cylindrical screen having a circumferentially continuous apertured zone to define an annular screening chamber between the rotor and the screen. The half-foil members are collectively at least axially co-extensive with the apertured zone and have a leading edge which, also collectively, is inclined at a spiral angle relative to the axis of the rotor such that during rotation, the collective leading edge of the half-foil members conduct large particles downwardly through the screening chamber. A selection of hydrodynamic foil configurations is provided in order to adapt to a wide range of pulp types and screening conditions.

Screening apparatus for papermaking pulp

In the floor of a pulp slurry inlet chamber an opening is provided. The opening is elongate and arranged substantially tangential to the outer, bounding wall of the chamber. Barriers of arcuate cross-section depend from the opening, at opposite ends of the opening. The barriers are incurvate, relative to the opening. The opening has a length across which junk cannot bridge. Consequently, the junk falls through the opening and is captured in an accumulator which underlies the opening. Knots substantially bridge across the opening, and impinge upon the arcuate barrier at the far end of the opening to be thrown upwardly for assimilation with the slurry flow coursing through the chamber. An elutriative liquid is supplied to the accumulator, at a given flow velocity, to wash up and out of the accumulator any organic particles which, due to irregularities, pass through the opening, to return the organic particles to the chamber.

Junk separator for, and in combination wtih, a pulp slurry inlet chamber

A hydrofoil in close proximity to an outboard surface of a rotatable slurry screen, and a hydrofoil in close proximity to an inboard surface of the screen, cooperate to create high and low slurry pressures at the surfaces which result in causing the slurry to surge through the screen to backwash the latter, thereby dislodging slurry-borne substances which tend to clog apertures in the screen.

Screening device for a fiber slurry, and a backwash means therefor

A hydrodynamic device for generating negative pressure excursions in a pulp slurry during fine screening, includes at least one half-foil member disposed on a substantially cylindrical outer surface of a rotor. The rotor is mounted within and co-axial with a substantially cylindrical screen having a circumferentially continuous apertured zone to define an annular screening chamber between the rotor and the screen. The half-foil member is collectively at least axially co-extensive with the apertured zone and has a leading edge which, also collectively, is inclined at a spiral angle relative to the axis of the rotor such that, in one embodiment, during rotation, the leading edge of the half-foil member conducts large particles downwardly through the screening chamber. A selection of hydrodynamic foil configurations is provided in order to adapt to a wide range of pulp types and screening conditions.

A screen aperture blinding prevention and liquid overflow prevention and level control apparatus for a knot drainer senses liquid level within the knot drainer and compares the sensed level to a setpoint level. Differences in the two levels generate control signals of appropriate magnitude and direction, and those control signals are transmitted to a valve whose degree of responsiveness and openness is adjusted to change the outflow rate of accepts liquor from the accepts chamber of the rejects separator. In addition, passive level control is provided in the discharge line for establishing accept flooded screen apertures regardless of variations of inflow and outflow rates during operation while active level control to create accept flow rate greater than, less than, or equal to inlet flow rate is provided by the combination of siphonic loop, barometric leg and control. Continuous flow of fiber and liquid through separating screen apertures is appropriately supervised by monitoring accepts chamber pressure.

Method for controlling liquid level in a knot drainer

A screening apparatus removes a fluid borne pulp fiber slurry from knots which have been concentrated from a pulp processing stream. A rotating radially symmetrical screen provides centrifugal screening to accept a pulp fiber slurry while an integrally connected spiral flight conveyor transports knots from the inner surface of the screen to a knot discharge chamber located axially above the screening chamber. Above the screening chamber but below the liquid level in the housing, a fiber free wash liquor is provided through a tangentially oriented nozzle in the direction of rotation of the spiral flight conveyor to release fibers from the knot surfaces thereby enabling them to pass through the screen. The screening apparatus also provides for removal of heavy tramp materials, for maintaining liquid level control, for minimizing air entrainment and foam formation, and for preventing clogging of the screen apertures and knot discharge outlet.

Apparatus for screening to remove knots from a fluid borne slurry of

An apparatus, for pressurized screening of a fiber/liquid suspension to separate the fibrous fraction into an accepts portion and a rejects portion, has a housing having an inlet with a heavy and large material trap, an accepts outlet, a rejects outlet, and a dilution liquid inlet. A hollow cylindrical screen having an open top and bottom communicates with the fibrous suspension inlet chamber and the rejects outlet chamber. Accepts fibers in the suspension pass through apertures in the screen to the accepts chamber and are discharged through the accepts outlet. Rejects discharge through the rejects chamber. A rotor having at least four regions, a closed top, and a bottom mounted drive mechanism is coaxially mounted within the screen. Hydrodynamic pulses are induced in the suspension in the screening region by a pattern of bumps and/or depressions impressed upon the rotor surface. The fibrous suspension is maintained at a relatively constant consistency within the screening region by the pumping action of the rotor and by providing dilution liquid to counteract thickening of the suspension. A dynamic bar screening device directs stones and other large objects out of the fluid stream and into an annular trap and also deflocculates the suspension.

Apparatus for pressurized screening of a fibrous material liquid

A screen and a coaxially radially spaced rotor provide a fluid passage for the fibrous material--liquid suspension. The rotor surface has the effect of pumping or assisting a flow of dilution liquid from the reject end towards the inlet end of the fluid passage, thereby partly or wholly offsetting the natural thickening of the suspension during screening.

Growing community of inventors

Nashua, NH, United States of America

Douglas L Young