Dissolved Gas Flotation Unit

dissolved gas flotation process diagram

Dissolved gas flotation process diagram

Dissolved gas unit allows the water and gas saturation in a contactor. A typical Dissolved gas unit works on 20 to 40 psig contact pressure, more gas can be saturated in higher pressure. The water is taken from the treated water; the gas saturated water is then injected into the floatation tank. The dissolved gas breaks out of solution in small diameter bubbles that contact the oil droplets in the water and bring them to the surface in a froth.

The typical dissolved gas unit installation takes an area of 0.2 to 0.5 scf/barrel of water to be treated with 2 and 4 gpm/ft2 flow rate. Retention times of 10 to 40 minutes and depths of between 6 and 9 feet are specified.

Dissolved gas units are not common in production operation since they are larger than dispersed gas units and most production facilities do not have vapor recovery units so the gas is not recycled.


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