An imaging technique for characterization of fluid flow pattern on industrial-scale column sieve trays

Abstract

Non-uniform flow patterns on distillation trays can result in significant losses in separation efficiency compared to conditions with straight chordal flow paths. To improve flow pattern via tray design revamps as well as for more accurate prediction of achievable separation efficiency, better understanding of the flow formation is required. This is, however, not straight forward since the evolving patterns depend on column and tray design as well as on operating conditions and may cover configurations with continuous liquid being pushed through a curtain of rising bubbles (bubble regime) or a continuous gas phase carrying the liquid as droplets (spray regime).In this study, the wire-mesh sensor technique was used to visualize flow patterns on larger trays. The technique tracks conductivity tracer pulses during their passage across the tray. A proper calibration routine was developed and a methodology is proposed to determine point liquid residence time distributions and weir-to-weir liquid velocities. Experiments were carried out in a tray column of 800mm diameter. The feasibility study included experiments at different liquid capacities and various outlet weir obstructions. Tray benchmark data at high spatio-temporal resolution were obtained, which are suitable for validation of CFD models for flow simulation of industrial-scale sieve trays.