Venturi eductor

Venturi = a converging and then diverging flow nozzle, used for metering and for creating a suction such as in eductors and ejectors. 

The essential difference between the air amplifier and the air eductor is in the diameter of the aperture through which the compressed air is expanded. That aperture is called a venturi. An equation which allows calculation of the performance of either device with a venturi is the Bernoulli Equation. ... 

Note the dependence of pressure change on circular channel diameter (D), all else being the same. It s to the fourth power That dependence is how one can design an air amplifier with a large diameter venturi and expect only a small pressure change sufficient to entrain additional air relative to an eductor with a small diameter venturi which would produce a substantial pressure change — a partial vacuum upstream. 

Vacuum eductor. Often this vacuum generator, usually a venturi, is installed on the panel and used during purge sequences. 

Eductor mixers introduce the air through tiny holes in the throat of small venturis installed on separate pipes transferring the liquor from the delay tank to the oxidizer. The large shear force at the air-liquor interface provides a high mass-transfer coefficient between the oxygen and the liquor. The air then bubbles upward through the oxidizer to accomplish the. sulfur flotation (Vancini and Lari, 1985). 

Figure 3.5 shows a cross section of a three-cell inductor dispersed gas flotation unit. Clean water from the effluent is pumped to a recirculation header (E) that feeds a series of venturi eductors (B). Water flowing through the eductor sucks gas from the vapor space (A) that is released at the nozzle (G) as a jet of small bubbles. The bubbles rise, causing flotation in the chamber (C), forming a froth (D) that is skimmed with a mechanical device at (F). 

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