ON THE EFFECT OF LIQUID HEIGHT ON THE FLOODING LOADING TRANSITION

It was proposed by J. M. Smith, M. M. C. G. Warmoeskerken and J. M. Smith that the flooding loading transition in an aerated vessel agitated by a Rushton turbine occurs when the volume rate of flow of liquid upwards arising from the entry of gas at the sparger Q//A//X, is equal to the volumetric pumping flow from the agitator, Q//p. In essence, it was suggested that Q//A//X could be estimated from work on bubble driven flows in reservoirs. Based on the authors work, it appears that the original concept, i. e. that the upward flow from the sparger (which must be dominated by the impeller flow) can be estimated by analogy with reservoir flows, is invalid. In fact, far from the flooding-loading transition being very sensitive to geometrical changes involving height as relationship would imply, it is very insensitive to it; and when it does have an effect, an increase in height leads to a reduction in N//F (at constant Q//G) or an increase in (Q//G)//F (at constant N), i. e. the opposite to what would be expected.