Influence of twisted tape and blade type turbulence promoters on the microfiltration of milk

Abstract

The aim of this research was to study influence of turbulence promoters on permeate flux improvement and energy savings during microfiltration of milk. Low pressure loss turbulence promoters, twisted tape and blade shaped static mixer, named Koflo, were used. The chosen turbulence promoters are of the same aspect ratio (ratio of pitch length to diameter of promoter) 2.5 and inserted into the tubular ceramic membrane (0.1 μm pore size). By applying turbulence promoters, fouling was reduced and the permeate fluxes were increased by a factor of three for twisted tape and by a factor of four for blade shaped static mixer. Intensity of turbulence in a module fitted with promoter depends on the applied cross flow rate. An increase of cross flow rate induces a rise of flux in the both modes of operation, with and without turbulence promoters. When compared at the same cross flow rate, the flux obtained by application of turbulence promoters is always higher than the flux obtained without promoters. The cross flow rates, under which the maximal flux improvement was achieved (300% for twisted tape and 320% for Koflo), are several folds lower than that applied in operation without promoter. In the presence of turbulence promoters permeate flux was increased as well as the pressure drop along membrane. Despite the higher pressure drop, operation with turbulence promoters provides significantly reduced energy consumption compared to operation without turbulence promoters.