Membrane ultrafiltration in a tubular module with a steel rod inserted concentrically for improved performance

Rising fluid velocity in the tubular-membrane module by inserting concentri cally a steel rod has two conflicting effects. One, the decrease in resista nce to permeation due to reduction in concentration polarization, is good f or ultrafiltration, while the other, the decrease in average transmembrane pressure due to increase in friction pressure loss, is bad for ultrafiltrat ion. It appears, therefore, that proper adjustment of fluid velocity as wel l as proper arrangement of the annular size of flow channel with a specifie d volumetric feed rate, might effectively suppress any undesirable resistan ce to permeation while still preserving an effective transmembrane pressure and thereby lead to improved performance of membrane ultrafiltration. It w as found that considerable improvement in permeate flux is obtainable by em ploying such a modified tubular module rather than using the open tubular m odule without an inner tube. The enlargement of power consumption for fluid flow due to the insertion of an inner tube has been also discussed. The im proved performance has been checked at same hydraulic dissipated power. (C) 2000 Elsevier Science B.V. All rights reserved.