Patent ID: 8137568

Claim:
An end drainage rotary vacuum filter drum for rotation about a central longitudinal axis, comprising a filtrate discharge end having an axially located discharge valve and a second non-discharge end, and further comprising: i) a cylindrical, perforated outer filter deck for supporting a layer of filtered material; ii) a cylindrical inner deck mounted for rotation about said central axis; iii) a plurality of longitudinal elements extending radially between and secured to said inner and outer decks thereby forming a plurality of longitudinally extending ducts extending between said non-discharge end and said discharge end of said filter drum; iv) a radially extending passageway adjacent said discharge end of said filter drum communicating between one or more of said longitudinally extending ducts at the radially outer end of said radially extending passageway and said axially located discharge valve at the radially inner end of said radially extending passageway; wherein said longitudinally extending ducts increase in cross-sectional area from the non-discharge end to the discharge end and said radially extending passageway is substantially constant in cross-sectional area from said outer end to said inner end in a direction perpendicular to the filtrate flow whereby the velocity of the filtrate flow is kept substantially constant from said non-discharge end to said discharge valve; wherein said radially extending passageway comprises two parallel end plates adjacent said discharge end.