Coupled CFD and 1-D dynamic modeling for the analysis of industrial Regenerative Thermal Oxidizers

The emissions of volatile organic compounds (VOCs) produced in many chemical and manufacturing sectors are strictly regulated. Regenerative thermal oxidizers (RTOs), which employ ceramic masses for heat recovery in a cyclic operation mode, represent a promising technology enabling process intensification, by providing both high efficiencies of VOC removal and energy savings. This study advances a modeling framework which combines a 1-D transient model with 3-D CFD simulations to assist the design of 3-canister RTOs, focusing on the fluid dynamics, thermal and chemical behavior at different instants within the operational cycles. The analysis shows how different inlet-outlet-purge configurations affect the efficiency of VOC removal, which shows a minimum when the central canister is the outlet, as corroborated by experimental data and the analysis of the gas residence time. Some critical conditions of flow and temperature uniformity are investigated, showing that a random packing can be inserted underneath each monolithic block to ensure gas uniformity with only a limited increase in pressure drops. The approach and results reported point towards the establishment of robust criteria for RTO intensification.