A novel design for a gas-inducing impeller at the lowest critical speed.

To disperse the unreacted overhead gas phase into the liquid in an agitated reactor without gas outlet, a gas-inducing impeller is usually employed. To determine the lowest critical rotating speed, the gas-induction mechanism was reconsidered by constituting a mechanical energy conservation equation between the gas inlet orifice in the gas phase and the gas outlet orifice in the liquid phase under a certain rotational speed. According to this model, the critical speed of the gas-inducing impeller could be basically determined by the submersion depth and the radial position of the gas outlet, and a novel design was proposed by introduction of six short pipes stretched radially from the axis of the impeller. The final design of the gas-inducing impeller was obtained by an optimal combination of the gas-inducing pipes, the blades of the impeller and the baffle dimension. [ABSTRACT FROM AUTHOR]