Zur Maßstabsübertragung beim Suspendieren im Rührgefäß

Scale-up of agitated vessels in the case of suspensions . In the scale-up of agitated vessels a decrease of specific power input ε is recommended in the case of suspensions. Up to now it has been assumed that turbulence is the reason for this decrease. This paper shows that there may also be a contribution due to decreasing wall areas causing less wall shear stresses and moreover a reduction of circulation due to lower cross-sectional areas per unit volume of the threads of flow. In the case of so-called ?complete suspension”? according to the ?1-s criterion”?, two mechanisms can be distinguished: On the one hand we have a lifting of solid particles without, and on the other hand such a lifting with formation of bulk accumulations of solids on the bottom of the vessel. In the first case, scale-up can be done as for a homogeneous distribution of the solid material. The specific power input ε is ～ μ⁰ up to ε ～ μ^?1 with the scale-up factor μ. In the second case (formation of dense solids clouds) a relationship ε ～ μ^m with m > 0 was found.     

Verfahrenstechnische Auslegungsunterlagen für Rührbehälter als Fermenter

Engineering design data for agitator vessels as fermentors . The article develops and collects design data for stirring vessels for calculation of mass and heat transfer and the flooding point and stirrer power requirements for aerated liquids. The data refer to low-viscosity, higher viscosity, and structure viscosity liquids with difering coalescence behaviour. The working data presented are used to derive results for a specific system (air/aqueous solution of carboxymethylcellulose) which illustrate decisive relationships and limitations arising from mass and heat transfer. There results important information for the operation, and choice, and scale-up of stirred fermentors.