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*Weight solubilities in water at one atm (760 mm Hg) in the absence of water vapor. tGas densities at one atm (760 mm Hg) in the absence of water vapor.

*Weight solubilities in water at one atm (760 mm Hg) in the absence of water vapor. tGas densities at one atm (760 mm Hg) in the absence of water vapor.

FIG. 7.18.2 Pressurization methods applied in flotation.

tention baffle are the only additions that are different from a conventional clarification unit.

The gas-to-solids weight ratio is a major design consideration. This ratio determines the operating pressure of the pressurization system. This weight ratio varies from 0.01 to 0.06, but 0.02 is sufficient in most applications. Environmental engineers should use bench-scale tests or, if possible, pilot-plant tests to determine the gas-to-solids weight ratio for each application. An increase in the gas-to-solids weight ratio increases (to a limiting value) the separation rate of the gas-solids mass. This relationship cannot be adequately predicted and must be established by testing.

Full- and partial-flow pressurization systems do not affect the size of the flotation vessel since the flow to the flotation vessel does not increase. However, recycle-flow pressurization systems increase the feed flow rate to the flotation vessel by the recycled amount. Thus, flotation vessel size must be larger for recycle-flow pressurization

FIG. 7.18.3 Typical flotation unit.

systems than for full- or partial-flow pressurization systems.

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