Some Effects of Particle Wettability in Agitated Solid‐Gas‐Liquid Systems: Gas‐Liquid Mass Transfer and the Dispersion of Floating Solids

Abstract

Abstract Two‐ and three‐phase systems have been studied using particles that are water‐wetted and denser than water and with similar sized, small floating particles, both wetted and non‐wetted. The parameters investigated have been the agitator speed required to disperse the different types of particles under sparged and non‐sparged conditions and rates of gas‐liquid mass transfer. With the wetted, dense particles, only at concentrations of > ∼20% w/w did the k L a fall significantly (by ∼20 to 30%) whilst solid suspension followed the trends of earlier work. With the less dense particles, even with < ∼1% w/w that were not wetted, it was very difficult to disperse them throughout the liquid phase, though up‐pumping impellers were more effective than radial. In addition, bubble size significantly increased and k L a fell by a factor of 2 to 3. With the wetted, less dense ones up to 2% w/w, uniform dispersion was achieved even at much lower speeds and k L a did not change compared to the case without solids.