Centrifuge apparatus

Claim 1

A centrifuge having a top-driven rotor bowl, a disc stack within said bowl, annular overflow means at the top of said bowl for discharging centrifugally clarified liquid from said bowl, said bowl including a hub in the bottom portion thereof and a driving shaft connected to said hub and extending upwardly through said overflow means, a first passageway for feed extending through said hub for conducting feed into said bowl for centrifugal separation therein during rotation of said bowl about the rotational axis of said shaft, with first inlet means for said first passageway annularly disposed about said axis, first accelerator means rotatable with said bowl and including at least one vane disposed at said first inlet means for accelerating feed directed thereto, nozzles peripherally arranged on said bowl about said axis for discharging heavy phase material from said bowl, a second passageway for conducting recycled heavy phase material to said bowl from a bottom portion of said bowl to the interior of said bowl adjacent said nozzles, with second inlet means for said second passageway annularly disposed about said axis, said second inlet means being in vertically spaced relationship with said first inlet means, second accelerator means rotable with said bowl and including at least one vane disposed at said second inlet means for accelerating recycled heavy phase material directed thereto, a stationary housing surrounding said bowl, a feed pipe extending upwardly through said housing toward the bottom portion of said bowl, means for directing feed from said feed pipe toward said first inlet means, and that improvement comprising: a sump at the bottom of said housing in communication with said nozzles through the annular space between said bowl and said housing, a tuBular riser for said sump extending upwardly therefrom and about said feed pipe, said riser at its upper end having an upwardly facing open end of annular configuration defined by its peripheral rim and said feed pipe to provide a well for heavy phase material being recycled to said bowl, and an impeller for directing heavy phase material from said well to said second inlet means, said impeller comprising at least one vane connected to said bowl for rotation therewith and extending downwardly from above the level of said rim to below the level of said rim and into contact with the heavy phase material in said well to cause rotation of the heavy phase material in the upper end of said riser and consequent outward projection of the heavy phase material into the second inlet means.