A modified version of the single loop recirculation model is
proposed for the simulation of the dynamics of turbine and propeller
agitated continuous systems. The model predictions characterise
experimentally determined responses for a variety of operating
conditions and a wide range of impeller speeds. The model is
verified, using thin fluids, for various diameter impellers placed
in vessels of different diameter.
Analytical expressions are obtained for batch mixing time using
a matrix technique, having formulated batch conditions by a reduction,
of the continuous flow model. Experimentally determined batch mixing
times appear to match the analytical solutions more favourably than
the predictions of various empirical correlations.
A new approach, based: on the intensity function, is suggested for
the assessment of continuous mixing time.
The continuous flow model parameter (q/Q), the ratio of impeller
pumping capacity to system throughput, is proposed as the first dynamic
scale-up rule. If held constant this criterion ensures identical
residence time distributions in the laboratory and pilot plant vessels.
A variance analysis assesses the merits of different feed inlet
positions, for the continuous case, and shows that inlet feed directed away
from the outlet stream and impeller region produces the most effective
Scale-up using constant impeller tip speed is shown to provide
an economic optimum for the scale-up of continuous systems.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.