ECN publication
Optimale regelstrategie voor een microfiltratie-membraaninstallatie : experimenten en procesmodel DWT-installatie
Published by: Publication date:
ECN 1-1-2000
ECN report number: Document type:
ECN-I--00-001 Other
Number of pages: Full text:
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An optimal process control strategy was designed, based on experimentsand a process model for a microfiltration membrane unit. The experiments were carried out with one module of an operational microfiltration membrane unit while processing contaminated water from laboratories. Therefore the quality of the processed water represents the variety of the operational unit. The experiments were carried out at different transmembrane pressures (TMP) and cross-flow velocities (LSS). The cake layer formation by fouling at these conditions and the resulting overall energy efficiency is quantified based on an analysis of the experiments and a series of simulations. Preliminary results indicate that permeate flow can be increased by increasing the TMP. The preliminary results indicate that a reduction of the cross-flow velocity (by constant TMP control) from 6.0 m/s to 4.5 m/s can result in a substantial decrease of the specific energy consumption (at least 35%). The starting point for the simulations was the choice of an appropriate process model for membrane fouling. For this purpose, two models for long-term membrane fouling were evaluated for experimental data obtained from the membrane installation from DWT (section Decontamination and Waste Treatment of the Nuclear Research Group (NRG) in Petten, Netherlands) during process. These models concerned, respectively, a precipitation model and a gel layer model. The results indicated that the gel layer model fitted best to the data of the installation. Therefore, this model was used in the following stages of investigation to an optimal process strategy. A series of simulations were carried out to determine an optimal strategy with respect to minimal specific energy consumption. Within the licensed envelope of process conditions, the most energy efficient operating conditions were identified. Practical issues relating to the control of the permeate-retentate ratio have been clarified. Similarities between a simplified gel layer and the experimental data required additional attention. 18 refs.

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