Abstract:
The literature available on the effect of vessel geometry, particle properties and liquid
properties on the distribution of solids in a mechanically stirred vessel has been
examined. This has shown that there are wide discrepancies between different authors
on each of these areas.
Solids concentrations have been measured using an electrical conductivity probe at
various positions in two stirred vessels 0.61m and 1.83m in diameter. Different impeller
designs were examined using A 310s and Pitched Blade Turbines to distribute the solids
in the vessel. Pitched Blade Turbines with different diameter ratios of D=T/3 and D=T/2
were used. The sand particles used-had diameters from 150 pm - 1050 pm.
It has been shown that constant power per unit volume is a reliable design rule for:
1. The effect o f vessel scale
2. The effect o f impeller diameter
3. The effect o f impeller design
on the distribution of solids in a mechanically agitated stirred standard vessel. It has also
been shown that the solids concentration data presented here can be correlated on the
basis of N mod = N (C )da{yPo~lD~5 J and the vessel operating conditions can be
characterised by a design methodology based on its use.
Two methods of modelling the data are presented which describe the system in terms of:
1. An array of oscillating spheres and
2. The 1-d sedimentation dispersion model.
These methods were found to model the data with different degrees of success and were
generally disappointing.
