Mass Transfer Studies in Pneumatic Reactors

Local mass transfer studies have been carried out in an external loop airlift reactor and indi cated the existence of significant non-uniformities in aeration capacity in the various sec tions of the reactor. The traditional assumption of a single well mixed unit with a single kL a value for external loop airlift reactors was found to be poor and cannot represent ade quately the reactor as a whole. The liquid head in the gas/liquid separator was found to have a significant negative effect on the local mass transfer coefficient kL a. Visualization of flow patterns showed the existence of strong vortices in the riser and downcomer which contributed to a reduction in local aeration capacity. Mass transfer experiments in an aerat ed tank showed that the aeration capacity can be reduced by half in viscous media but im proved significantly in the presence of salts.