Gas-liquid vortex mixer and method

An apparatus for mixing gas and liquid comprising:

• a draft tube having an inlet end and an outlet end and defining a central axis;
• impeller means at least partially inside the draft tube, the impeller means being positioned in a body of the liquid sufficiently close to a surface of the liquid for drawing the liquid through the draft tube and creating at least one gas-filled vortex in the liquid extending from the surface of the liquid;
• inlet baffle means adjacent the inlet end of the draft tube for reducing pre-rotation of the liquid as it enters the draft tube, wherein the inlet baffle means and the impeller means have a clearance of less than about 2 inches and less than about 5 percent of an inner diameter of the draft tube;
• and
• shear inducing outlet baffle means adjacent the outlet end of the draft tube in close proximity and directly adjacent to the impeller means for creating high shear rates in the liquid as it passes from the impeller means through the outlet end of the draft tube, wherein the shear inducing outlet baffle means and the impeller means have a clearance of less than about 1 inch and less than about 2 percent of the inner diameter of the draft tube, and there are no structural components located between the shear inducing outlet baffle means and the impeller means.

A method of mixing gas and liquid, the method comprising:

• providing a draft tube having an inlet end and an outlet end;
• mounting an impeller at least partially within the draft tube;
• positioning at least one inlet baffle adjacent the inlet end of the draft tube in close proximity of the impeller, wherein the at least one inlet baffle and the impeller have a clearance of less than about 2 inches and less than about 5 percent of an inner diameter of the draft tube;
• positioning at least one outlet baffle adjacent the outlet end of the draft tube in close proximity and directly adjacent to the impeller, wherein the at least one outlet baffle and the impeller have a clearance of less than about 1 inch and less than about 2 percent of the inner diameter of the draft tube, and there are no structural components located between the at least one outlet baffle and the impeller;
• positioning the draft tube in a body of liquid to be treated with the impeller being positioned in the body of liquid in close proximity to a surface of the liquid;
• and
• rotating the impeller to thereby draw the liquid through the draft tube and create at least one gas-filled vortex in the liquid extending from the surface of the liquid.

An apparatus for mixing gas and liquid comprising:

• a draft tube having an inlet end, an outlet end and an inner diameter of from about 0.3 to about 5 feet;
• at least one impeller rotatably mounted at least partially inside the draft tube having at least one leading edge and at least one trailing edge, the at least one impeller being positioned in a body of the liquid sufficiently close to a surface of the liquid wherein rotation of the at least one impeller draws the liquid through the draft tube and creates at least one gas-filled vortex in the liquid extending from the surface of the liquid;
• at least one inlet baffle adjacent the inlet end of the draft tube in close proximity to the at least one leading edge of the impeller, wherein the at least one inlet baffle and the at least one leading edge of the impeller have a clearance of less than about 10 inches;
• and
• at least one outlet baffle adjacent the outlet end of the draft tube in close proximity and directly adjacent to the at least one trailing edge of the impeller, wherein the at least one outlet baffle and the at least one trailing edge of the impeller have a clearance of less than about 3 inches, and there are no structural components located between the at least one outlet baffle and the at least one trailing edge of the impeller.

An apparatus for mixing gas and liquid comprising:

• a draft tube having an inlet end and an outlet end defining a central axis and having an inner diameter of from about 0.3 to about 5 feet;
• impeller means at least partially inside the draft tube, the impeller means being positioned in a body of the liquid sufficiently close to a surface of the liquid for drawing the liquid through the draft tube and creating at least one gas-filled vortex in the liquid extending from the surface of the liquid;
• inlet baffle means adjacent the inlet end of the draft tube for reducing pre-rotation of the liquid as it enters the draft tube, wherein the inlet baffle means and the impeller means have a clearance of less than about 10 inches;
• and
• shear inducing outlet baffle means adjacent the outlet end of the draft tube in close proximity and directly adjacent to the impeller means for creating high shear rates in the liquid as it passes from the impeller means through the outlet end of the draft tube, wherein the shear inducing outlet baffle means and the impeller means have a clearance of less than about 3 inches, and there are no structural components located between the shear inducing outlet baffle means and the impeller means.

A method of mixing gas and liquid, the method comprising:

• providing a draft tube having an inlet end, an outlet end and an inner diameter of from about 0.3 to about 5 feet;
• mounting an impeller at least partially within the draft tube;
• positioning at least one inlet baffle adjacent the inlet end of the draft tube in close proximity of the impeller, wherein the at least one inlet baffle and the impeller have a clearance of less than about 10 inches;
• positioning at least one outlet baffle adjacent the outlet end of the draft tube in close proximity and directly adjacent to the impeller, wherein the at least one outlet baffle and the impeller have a clearance of less than about 3 inches, and there are no structural components located between the at least one outlet baffle and the impeller;
• positioning the draft tube in a body of liquid to be treated with the impeller being positioned in the body of liquid in close proximity to a surface of the liquid;
• and
• rotating the impeller to thereby draw the liquid through the draft tube and create at least one gas-filled vortex in the liquid extending from the surface of the liquid.