Dynamic shaft seal for pumping fibrous slurries

A dynamic shaft seal device for a fluid handling apparatus for pumping fibrous slurries, the fluid handling apparatus comprising an impeller mounted on a rotating shaft disposed in a pump housing, the shaft extending through an aperture extending from the pump housing into an impeller casing forming part of the pump housing, prime mover means adapted to rotate the shaft and the impeller, a slurry of a dispersed fibrous material in a fluid disposed in the impeller casing, a repeller chamber formed in the pump housing and in communication with the impeller casing, the repeller chamber being generally sealed from the introduction of a flushing fluid into the outer circumferential portion of the chamber, the repeller chamber located in proximity to the aperture, a repeller attached for rotation with the shaft, the repeller extending into the repeller chamber to force a portion of the fluid in the impeller casing to move in a vortex in a direction away from the aperture, means associated with the repeller to apply shear forces to the fluid vortex, and create circulatory flow within the vortex to maintain the dispersion of the fibrous material in the slurry, the means including fixed vanes extending radially inward from the annular surface of the repeller chamber and rotary vanes mounted on the repeller, said rotary vanes having outer surfaces which pass closely adjacent the inner surfaces of the fixed vanes to provide a zone of recirculation in the fluid disposed between the repeller and the annular surface of the repeller chamber as the repeller rotates.