Patent attributes
A method of treating pulp on a porous surface of a rotating drum cylinder having a lower drum portion in a vat of pulp slurry and a radial array of filtrate conduits including: as the porous surface of the drum rotates through the vat, drawing filtrate from the slurry through the porous surface by the application of a suction to the filtrate conduits vacuum; draining the filtrate from the filtrate conduits into the filtrate chamber and to a filtrate suction conduit extending to an elevation below the vat; forming a pulp mat on the porous surface which passes filtrate and substantially blocks fibers in the pulp slurry; removing the pulp mat on the porous surface from the vat as the drum rotates; draining filtrate from the filtrate suction conduit, and before excessive gases passing through the porous surface enter the filtrate conduits, switching a fluid flow downstream of the filtrate conduits to a gas vent passage offset and below from a drum rotational axis.
