Dynamic cross flow filtration with Novoflow's single shaft disk filters

摘要

Dynamic cross flow filtration means rotating filter elements for this purpose. Rotating filter elements allow for decoupling of overflow velocity from transmembrane pressure (TMP). Considerable energy savings are realized compared to conventional tubular systems, because there is no need for constant circulation (pumping) of the feed over the membranes in order to generate shear forces. The combination of centrifugal and shear forces in dynamic cross flow modules improves control of cover layer build-up which extends operating life. Novoflow has specialized on compact and modular single shaft designs and has developed a proprietary process of disk manufacturing from almost any flat membranes. Applications in many fields have proven the economic viability of the concept. Dynamic cross flow technology has shown advantages for the application of high performance membranes. These are very thin and hard membranes with absolute pore sizes and open outflow, i.e. no drainage layers and support structure. In the absence of complex support structures (with tortuous channels), flux performances of high performance membranes reach by orders of magnitude higher levels at much lower filtration pressures (TMP) than conventional membranes. On the other hand, this higher performance causes higher concentration polarization and fast cover layer build-up on the concentrate/retentate side. Novoflow's dynamic cross flow filtration design has proven to be an ideal way to remove the accelerated cover layer build-up for high performance membranes.