Experimental results relating to the hydrodynamic behaviour of an impi
nging-stream reactor are presented and discussed. The parameters varie
d were the gas flow rate and the liquid flow rate while the quantities
measured were the gas holdup, the mean bubble diameter and the absolu
te bubble velocity in the main reactor tube. From these quantities, th
e internal gas recirculation rate and the gas flow ratio have been det
ermined. The internal gas recirculation rate is important in evaluatin
g the mass-transfer performance of the impinging-stream reactor.