System for enhanced gas dissolution having a hood positioned over the impeller with segregating rings

A system for the dissolution of gas in a large body of liquid comprising:

• (a) an impeller positioned below the surface of the large body of liquid and adapted to cause the passage of a gas-liquid mixture downwardly in said large body of liquid;
• (b) a floating hood positioned over said impeller and of sufficient size to capture most of the undissolved gas that separates from a liquid rich in dissolved gas and floats and to the surface of said large body of liquid for recirculation to said impeller;
• and
• (c) a conduit for introducing a feed gas stream beneath said floating hood and directly into said large body of liquid, so that bubbles of the gas are caused by the suction of said impeller to pass with liquid, as a gas-liquid mixture, downward in said large body of liquid,
• (d) at least one segregation ring positioned under said floating hood and extending below the surface of said large body of liquid such that a first inner region between said ring and said impeller, and a second outer region between said ring and an outer diameter of said floating hood are created, and wherein said bubbles of said gas are segregated by their relative size, such that larger bubbles containing comparatively high purity oxygen are collected in said inner region and smaller bubbles containing comparatively low purity oxygen are collected in said outer region;
• (e) a back pressure regulator located in said floating hood adjacent to said outer diameter of said floating hood, for purging said comparatively low purity oxygen gas;
• whereby the liquid rich in dissolved gas, because of the absence of container vessel walls, is dispersed into the large body of liquid, while undissolved gas, due to its buoyancy, floats to the surface of said large body of liquid and is captured for recirculation, resulting in essentially complete utilization of the feed gas stream.