Bearingless Spinfilter
Dynamic membrane filtration offers higher long-term filtration fluxes due to self-cleaning effects induced by the rotation of the filter cartridge. Bearingless motors enable a hermetically sealed plug-and-play system of the mechatronics from the processed fluids.
At HPE, a levitating spinfilter with bearingless electric motors is developed for ultra-clean applications as required in the microelectronics and pharmaceutical industries. The rotation of the membrane generates a flow within the filter module, which keeps the membrane clean. The bearingless operation prevents any particle contamination by wear of moving parts in the rotating filter. However, an open gap interface between the feed fluid and the filtrate is created by the contactless nature of the system, which can lead to filtrate impurities due to internal leakage flows.
Therefore different topologies of bearingless spinfilters are investigated with internal pressure compensation methods to reduce the leakage flow and therefore increase the filtrate purity in the system. Turbomachinery elements such as labyrinth seals and integrated impellers are employed to prevent any remixing of the filtered medium.
The developed different filter topologies are tested in separation experiments with live yeast cells as a model fluid for a cell culture. The spinfilter is designed and operated such that the induced shear damage to the cells is minimised. A high cell viability is essential to maximise the yield in biotech manufacturing processes.