Optimizing Energy Efficiency in Low Temperature Drying by Zeolite Adsorption and Process Integration

摘要

Drying is an energy intensive process, with low efficiencies, particularly at low dryingrntemperatures required for heat-sensitive products. This work presents an energyrnefficient method for drying heat-sensitive products based on drying air dehumidificationrnby zeolites and process integration. Two optimization approaches are considered:rnsequential and simultaneous. In the sequential approach, a zeolite adsorption dryer isrnoptimized for energy efficiency, subject to product temperature and final moisturernconstraints using the zeolite, drying and regeneration air flowrates as well as thernregeneration air inlet temperature as decision variables. Heat is then optimally recoveredrnfrom the process exhaust streams using pinch analysis. In the simultaneous method, heatrnrecovery is considered an integral part of the drying process and the entire systemrnsimultaneously optimized. Since the heat recovery stream properties are now unknown arnpriori, the pinch point is not unique but determined by optimization. The sequential andrnsimultaneous methods reduce energy consumption by about 45 % and 55 %rnrespectively, compared to a conventional convective dryer at the same dryingrntemperature of 50℃.