Dissolution mass transfer in a turbine agitated baffled vessel

Mass transfer coefficients were measured for the dissolution of crystalline electrolytes suspended in a baffled vessel by means of disc turbines. A 3-fold range of density differences, a 5-fold range of diffusivities and a 50-fold range of particle size were covered and the effect of impeller speed, size and clearance from the base was studied. The increase in coefficent with speed is both a function of the clearance and solid density and size and is difficult to quantify. However, in the most economic configuration of small clearance and large impeller, this is not of great importance since the coefficient increases but slowly with speed and the minimum suspended coefficient can be calculated. This is done by means of a slip velocity theory which has been extended to include larger particles, which allows for the effect of concentration dependent physical properties and which is based on the impeller speed at which particle suspension occurs.