Filter cake

A filter cake of the retained on a filter substances formed (usually solids). The filter cake increases during the filtration, " thick ", as continuous solids are retained. With increasing layer thickness of the filter cake results in both the positive effect of the improved deposition and the negative effect of increasing flow resistance of the filter cake. The latter leads to an increasing power demand to flow through the filter or with a limited power to a steady decrease of the flow rate through the filter. In addition, the forces acting on the filter cake forces can cause it to so-called cake compression - a quasi sudden compression of the filter cake and thus a sharp increase in the flow resistance - is coming. The filter cake must therefore be removed from the filter, for example by back-flushing or in the gas phase usually by introducing a pressure pulse on the discharge side of the filter medium after a certain time.

In the process of membrane technology greatly through the filter cake formation ( fouling ) is influenced at ultra-and microfiltration. The effect may be so strong that in a micro- filtration, ultrafiltration. The minimization of these are also referred to as fouling in this area appearance of the filter cake formation is the main reason (besides the pinch effect in filtration by means of hollow fibers) for the application of energy-intensive cross-flow filtration.

• Filtration