RAGLESS PROPELLER DRAFT TUBE MIXER

摘要

A draft tube mixer is disclosed particularly adapted for use with digestion processes and apparatus wherein a vertical shaft (13) is driven by motor (15) through a suitable drive (14) to rotate a ragless propeller (12). The propeller (12) has a series of three lobes or blades (40-42) which are concentrically arranged at 120 DEG apart positions so that the minimum diameter of the blades are at the ends of a hub (43) from which the blades integrally extend. The blades extend over the length of the hub over about a 360 DEG of rotary motion. The blades (40-42) are symmetrical from their ends to the mid points on the vanes from either direction top or bottom so that the propeller is reversible without loss of efficiency. The leading edge (50) of each of the blades regresses from a point from the start of the blade progression tangent to the outside of the hub at each end so that this falling away of the angle of attack of the blade causes any debris striking the blade, such as rags or string to fall away outwardly of the blade hub so that it does not ball up or otherwise adhere to the hub area.