Scale-up of the necessary power input in stirred vessels with suspensions

One of the most essential problems in dealing with solid-liquid suspensions in stirred vessels is the determination of a reliable scale-up rule from small stirred tanks to large vessels on an industrial production scale. According to a new approach based on physical modelling of the complex fluid dynamics, the necessary power input in stirred suspensions can be calculated as a sum of the circulation power and the sinking power of a particle swarm. The following results, which are compared with a great variety of experimental data in the literature, reveal that there is no simple and constant scale-up rule applicable to describe the power input for a large range of suspension properties, tank size, geometrical conditions or comparable suspension criteria.