(31a) Column Profiles for Membrane Column Sections

A novel graphical method of analysing continuous membrane separation systems has been developed. The method is applicable to all counter- and co-current membrane modules ? single-stage, cascades, and membrane columns. All configurations can be broken down into ?column sections?, no matter how complex the arrangement. Each column section, which resembles a typical single-stage separator, is modelled using the difference point equation. The difference point equation tracks the change in the retentate composition down the length of the column section. For demonstration purposes, a simple constant relative permeability flux model is employed to determine the permeate composition as well as the continually changing retentate flow. All possible operating conditions of a column section are explored. Each condition is a result of the relationships between the flows and compositions at the top of a column section. Using the difference point equation, column profiles for each condition can be plotted. The behaviour of the profiles is discussed both mathematically and graphically. This innovative way of investigating membrane processes provides a unique way of synthesizing and designing them.