Radoslav Paulen will have his PhD defense on Wednesday, September 12, 2012 at 11:00 in room nr. 641. His PhD thesis is entitled "Optimal Operation of Batch Membrane Processes".
This work considers the problem of finding the optimal control of batch membrane diafiltration processes. Diafiltration is known as an effective method to separate at least two solutes from given solution (liquor) at the base of their different molecular (particle) effective sizes. The goal is to concentrate (increase the concentration of) the solute(s) with bigger particle size(s) usually called macro-solute and to remove impurities, i.e. to dilute (decrease the concentration of) solute(s) with smaller particle size(s) traditionally denoted as micro-solute. The whole process is described by the set of ordinary differential equations and thus methods of dynamic optimization (open-loop optimal control) can be used to establish optimal operation of these processes. Our task is to determine how a solute-free solvent (diluant) should be dynamically added to feed solution tank throughout the process run to achieve given separation goal in minimum time or with minimum amount of added diluant. We use analytical approach, Pontryagin's Minimum Principle, to identify candidates for optimal control taking into account the necessary conditions for optimality. Based on these, we derive optimal operational policies for batch membrane processes of several types. Direct (discrete) numerical method of dynamic optimization, Control Vector Parameterization, is then used to confirm the theoretical findings and to obtain the optimal diluant utilization for particular process and instance.