Pulse free stock screen and combination pump

摘要

A paper machine screening apparatus generally includes a centrifugal pump member mounted for rotation about the axis of a tubular screen plate. A delivery passageway extends concentrically about the pump impeller for receiving pumped stock flow and includes an annular axially extending passage formed between a ribbed hub surface of the pump and the screen. Flow through the screen is passed from the screening apparatus to headboxes. Downstream of the annular passage is an end cavity for receiving particles unable to pass through the screen holes which are washed into the end cavity by the axial flow through the annular passage. The ribbings on the hub surface serve to agitate the stock flow to raise pressure forces tending to force flow out through the screen holes.