Real time control in water resource operations.

摘要

The objective of this research is to determine what is a time optimal control for diafiltration membrane separation processes. Diafiltration membrane separation is a dewatering process of a slurry from an initial bulk phase concentration (C0) to a final bulk phase concentration (C b,f). When rates of the material entering the system match rates leaving as a permeate, it is termed permeate matching diafiltration. Managing the controlled variables of the system in a time optimal manner maximizes the solid production capacity. Time optimal controllers have been used in many practical applications, but it has not been applied to water resources management.; The case study for this dissertation is a particular ultrafiltration process (UFP) to be used at the Hanford Department of Energy (DOE) facility, which is a pinch-point of a proposed Waste Treatment Plant (WTP) for the treatment of low activity waste (LAW) and high level waste (HLW). Improving the performance of the UFP will directly improve the performance of the WTP. It is asserted that the feed into the UFP and transmembrane pressure differential (TMP) should be allowed to vary with time to minimize the time needed to go from C 0 to Cb,f. This form of diafiltration is termed time optimal diafiltration.; It will be shown that permeate matching diafiltration and time optimal diafiltration are equivalent in terms of dewatering times, but that permeate matching diafiltration is open loop. Time optimal diafiltration will be shown to exhibit feedback through the use of sliding mode control. The advantage of this closed loop approach will be demonstrated. Furthermore, an empirical relationship is derived for the optimal time of dewatering associated with permeate matching diafiltration that can be used for sizing ultrafiltration processes.