Abstract: A fluid seal having differing fluid levels is provided on opposite sides of a downwardly opening cup-shaped container that is longitudinally lapped by an upwardly opening annular container that is sealed to a vessel such that the lip of the cup-shaped container is submerged. The fluid seal creates a hydrostatic pressure barrier between ambient and a vessel, for example at a rotating vertical shaft. Relatively high speeds are permitted without leakage due to a number of internal horizontal and vertical baffles on one or more walls of the annular container. Barrier fluid losses due to evaporation or the like can be replaced in an embodiment wherein condensed process fluid is used as the barrier fluid, and wherein excess barrier fluid is returned to the vessel while maintaining a differential pressure barrier via the seal.

Abstract: A vertical draft tube submerged turbine mixer/aerator includes an impeller rotatedly disposed within the draft tube above an aerator. A single tiplet extends downwardly from the lower surface of each impeller blade in proximity to the blade tip for improving gas to liquid mass transfer efficiency of the mixer/aerator.

Abstract: A hydrofoil impeller includes three impeller blades attached to a hub. Each impeller blade includes a flat section and a curved section which terminates in a tip portion. The flat section has a root portion proximate the hub and which forms a predetermined root angle with respect to a plane perpendicular to the vertical axis of the impeller. The curved section is separated from the flat portion by a bend line. The curved section is bent downwardly from the plane of the flat section along the bend line. The bend line is oriented with respect to the impeller blade such that the blade tip angle is changed as the bend is formed. Accordingly, the bend is used to set the proper tip angle. The blade angle increases from the tip inward to the bend line, then becomes a constant where attached to the hub. The camber increase from the tip inward to the bend line, then falls to zero where attached to the hub.