Flow Pattern Optimization of a Sieve Plate Extraction Column Using CFD Simulation and PIV Measurement

Present work deals with flow pattern optimization of the continuous phase in a sieve plate extraction column using both computational fluid dynamics (CFD) simulation and particle image velocimetry (PIV) measurement. Firstly, flow pattern of a sieve plate extraction column (SPEC) with traditional configuration was simulated and it was found that there was a very large reverse flow region between every two plates. Then, flow pattern was optimized with the objective of minimizing reverse flow area since the reverse flow can decrease the mass transfer efficiency. Step by step, internal structure of the column was modified to minimize the reverse flow area and with the modification, flow pattern of the continuous phase was optimized. The strategies consist of inclining downcomers, adding diversion baffles, slotting the downcomers and diversion baffles, adjusting the number and size of slots and fixing small baffles laterally at the top slots on downcomers. In the course of evolution, five generations (11 types) of SPEC with different internal configuration were proposed and flow patterns in these columns were investigated. Finally, an optimal flow pattern nearly no reverse flow region was obtained. PIV experiments of three types of columns in 11 were carried out and it was found that the results of simulations and experiments are in good agreement. Besides, the mass transfer performances of all columns were investigated by CFD simulation and it was found that mass transfer efficiency was improved as the flow pattern was optimized. The flow pattern optimization strategies proposed here can be extended to the design of other process equipment such as distillation and reaction.

Keywords: flow pattern optimization, extraction column, CFD, PIV