Heavy oil microfiltration using ceramic monolith membranes

Removal of asphaltenes from Cold Lake heavy oil by microfiltration has been investigated at temperatures of up to 190°C, using ceramic monolith membranes with average pore size in the range 0.1–1.4 μm. As observed in previous work using single-tube ceramic membranes (pore size 0.02–0.1 μm), the pores of the membrane restrict during an initial fouling period that results in increased asphaltene rejection (up to 80%) and reduced permeate flux. However, following this initial fouling period, both permeate flux and asphaltene rejection are shown to be of similar magnitude and independent of membrane pore size, evidence for the presence of a gel-layer on the membrane tube wall. Experiments designed to simulate heavy oil ultrafiltration in a membrane cascade revealed an increase in the fouled membrane resistance with an increase in the feed asphaltene content, and this trend is ascribed to changes in the properties of the gel-layer that occur with changes in the asphaltene concentration.