Design of ceramic membrane supports: permeability, tensile strength and stress

A membrane support provides mechanical strength to a membrane top layer to withstand the stress induced by the pressure difference applied over the entire membrane and must simultaneously have a low resistance to the filtrate flow. In this paper an experimental and a theoretical approach toward the design of a ceramic membrane support are combined. In the experimental part, the influence of the particle size, sintering time and sintering temperature on the permeability and strength of supports made by colloidal processing of submicron-sized alumina powders is investigated and compared with dry-pressed samples. In the theoretical part, a condensed expert system is set up that comprises the main relations necessary to describe the maximum filtrate flow of an incompressible fluid through a multilayered tubular inorganic membrane. The model can be adapted to describe other geometries and fluids. From calculations it becomes clear that optimum values exist for the dimensions and material properties of the support. Hence, support design is not straightforward and needs a comprehensive approach incorporating simultaneously all relevant design characteristics