The classic way to sparge air into an agitated tank, if side entry agitators are being used, is with a Lance delivery system.  The Lance is placed in front of the propeller to push the gas into the volume and have a high shear zone where the high power dissipation at the impeller maximizes mass transfer efficiency. The problem with the Lance is that at some point the gas volume being injected will exceed the ability of the impeller to keep the gas from collecting at the low pressure zone of the impeller (center). 

In operation, the gas may pull in to the low pressure zone but the propeller can recover to prevent gas build up. Once the propeller cannot recover, propeller flooding occurs, and this is a calculable amount.  The propeller becomes engulfed in an air pocket, pumping stops and loads increase on the mechanical system.

PMSL has designed and patented the AirWing™ gas dispersion system.  The AirWing prevents propeller flooding by taking the lance and focusing the gas flow away from the propeller.  Next, by adding the “wing”, the spiral flow coming from the propeller (that can hold up gas) is reduced, making it almost impossible to flood the propeller.  The results are higher mass transfer efficiencies at higher gas rates and the flexibility to increase gas rates in the future without having to modify agitation equipment.

The next part to make better is the propeller by fine tuning the power number to be process specific.  

Do you have a gas dispersion process that could benefit from a tune-up?  Let us know! 

This blog was written by Bob Dowd.
Bob Dowd has been with PMSL for over 20 years and is a market specialist.