Shaft seal with seal impeller for materials processing machinery

Abstract

Shaft sealing for a materials processing rotor at the juncture of the rotor's shaft with its surrounding machine housing. The sealing apparatus includes a seal stator carried on the machine housing and through which the shaft of the rotor extends. A seal impeller, having a plurality of elongated, oblique impeller vanes forming its perimeter, is carried on the rotor shaft within the seal stator. Fluid restraining means extends between the machine housing and the rotor shaft, at a location outboard of the seal impeller, to provide a fluid dam, and fluid injection means extends from the exterior of the machine housing to a position between the fluid restraining means and the seal impeller. In a preferred practice of the invention, a fluid, such as water, is continuously injected from the exterior of the machine to the position forward of the fluid restraining means and contemporaneously the seal impeller is rotated within the seal stator at a speed sufficient to induce a pressure less than or equal to the pressure at which the material is being processed, at a position immediately adjacent and forward of the fluid restraining means. After injection, the fluid is directed along a path, obliquely of the center line of the rotor shaft, through the space between the stator and the impeller and then expelled into the material being processed.