Screw and head assembly for processing whole grains and cellulosic

Abstract

An improved extruder screw section and barrel assembly is provided which is especially designed for effective extrusion processing of whole or cracked grains or cellulosic materials which can subsequently be converted to alcohol. The overall assembly includes an elongated, tubular head section presenting on the interior thereof at least one relatively sharp cutting edge (preferably in the form of a spiral rib), along with an elongated, axially rotatable screw section disposed within the head section. The screw section is characterized by a series of separate, elongated, circumferentially spaced grooves generally along the length of the section which progressively decrease in depth from one side margin of the grooves to the other, in the direction of screw rotation; thus, the material being processed is, by virtue of screw rotation and the groove configuration, pushed radially outwardly against the cutting edge presented by the surrounding barrel section. In this manner, the material is effectively subdivided or sliced to enhance the cooking thereof and maximize downstream alcohol production. In preferred forms, the screw section grooves are of progressively decreasing width and depth from the input end thereof to the output end, in order to increase the compressive forces on the material along the length of the section.