Cleaning of filter media by pulsed flow – Establishment of dimensionless operation numbers describing the cleaning result

• The cleaning of filter media with the help of a pulsed flow was developed and was proved to be a promising cleaning method.
• With decreasing pulse pauses the cleaning grade increases.
• The pulsed flow provides a higher cleaning result than the cleaning with constant flow (18% higher).
• With the help of a dimensional analysis dimensionless operations numbers could be established describing the cleaning behavior.

The demand for cleaning-in-place (CIP) equipment in the pharmaceutical and food industries is steadily increasing. In filtration processes, the filter medium is the worst to clean. Thus, in this paper, a cleaning method for filter media is presented and the cleaning experiments are evaluated referring to their cleaning grades. Cleaning is by a pulsed flow generated by a fast switching solenoid valve, which is connected to a nozzle in front of the filter medium. In the study, parameters like frequency, velocity of the pulse, pulse duration and distance between nozzle and filter medium are varied and it will be discussed which operating conditions achieve the best cleaning results. The aim of the cleaning method is to increase the cleaning grades of the filter media, to reduce the consumption of the cleaning solution and, hence, to minimize the process costs. In this paper, also a dimensionless operation number is developed, by means of which the cleaning behavior of different filter media can be predicted. The investigations showed that the cleaning grade increases with decreasing intervals between two pulses and that the pulse duration has no significant influence on the cleaning grade. In summary it can be stated, that cleaning by pulsed flow is a promising cleaning method for filter media.