Conventional vs. Regenerative Froth

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Packed columns with gas–liquid countercurrent flows are commonly used for gas scrubbing and stripping. Tower packing, including random and structured packing, is the most common system that is used to remove gases (such as CO2) from the main gas streams. High mass–transfer capacity (achieved by raising the gas–liquid interfacial area) and low pressure drop, are essential in industrial economic requirements. Thus, a well-designed and highly efficient packing is important due to a greater demand for packed towers in industry.​

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Unlike conventional counterflow absorbers, in the Regenerative Froth Contactor (RFC) gas and the solvent both flow downward in a 'co-flow' configuration. The RFC packing consists of proprietary convoluted screens that trigger unstable pulsing flow.  Bands of froth propagate down the column.  The contact surface area now consists of millions of bubble walls and droplets that are created as the bands of froth collapse and are regenerated.

 

The superficial gas velocity in the column is much higher than the rate the froth bands move down the column, so any volume of gas will pass through multiple froth bands before exiting the bottom of the absorber.

 

Extreme turbulence provides excellent mixing and prevents solids from sticking to and fouling the internal structure.  Even when materials are precipitating within the contactor the particle size is limited and solids remain in suspension throughout the process.

 

The gas velocity is twice as high as in a typical absorber, allowing the same flue gas treatment volume in an absorber with half the footprint (area) of a counterflow system.

 

The mass-transfer rate between gas and liquid is four to five times that experienced in conventional absorption columns. This allows equivalent performance in a column 50%-60% shorter than previously possible.