CFD Study of the Weeping and Flooding Effects in a Nonsymmetrical Sparger in a Stirred Tank

Abstract

The hydrodynamics of a 13-orifice, nonsymmetrical, gas sparger in a stirred tank was analyzed using computational fluid dynamics (CFD). The mathematical model of the multiphase gas−liquid interaction and its solution was also explored. Two phenomena in the gas sparger were inferred from the experiments, which were explained by the results from the CFD simulations: (a) backflow resulting in "flooding", whose magnitude depends on operating variables such as total gas flow at the inlet, stirring speed, and liquid level, and (b) "weeping" that affects the bubbling operation of some of the orifices. It was observed that weeping occurred at 5 m/s and below. The CFD results for the sparger operating with a Rushton turbine revealed a different behavior of each orifice. A thorough understanding of these phenomena within a small-to medium-size stirred tank could assist researchers in improving the operation of multiphase stirred tanks with spargers.