Design optimization of a rotating packed bed based on dry hydraulic performance

Abstract

The current study focuses on enhancing the fidelity of the hydraulic performance of Rotating Packed Beds (RPB) by modifying the conventional geometrical construction of the inner cavity, outlet pipe, and its packing. RPB technology has been playing an increasing role in intensifying different petrochemical processes, such as CO2 capture, due to the potential of a several-order-of-magnitude mass transfer enhancement induced by the HiGee field. In this context, four novel geometries of the RPB are proposed and analyzed using a validated CFD model that utilizes the porous media approach to model the pressure losses in the RPB packing. The impact of liquid distributor was also investigated and compared to the original design. Results of the modified geometries conclude that optimizing the flow pattern at the exit of the packing by modifying the inner cavity's shape reduces the total pressure drops by up to 22%. At the same time, it is found that a further decrease of 13% in the pressure drop can be achieved by attaching a nozzle at the entry of the outlet pipe. On the other hand, the modified packing that imposes a constant radial flow velocity increases the packing's pressure drop by 10%. Furthermore, the data analysis show that a lower pressure drop within the inner cavity could be achieved, in principle, by regulating the exit packing velocity or raising the free vortex pressure. Finally, it is noted that the gross pressure drop reduction, which is be obtained from combining the two former modifications, can reach up to 33% at the high gas volume flow rates. This reduction accounts for 60% of the inner cavity pressure drop, which can help avoid costly and complicated engineering designs.