Control of reflux and reboil flow rates for milli and micro distillation

An accurate control of reflux and reboil flow rates for small scale distillation unit has been evaluated. Its feasibility was studied with a distillation column with good results. The distillation column was planar in shape, and it was operated in a horizontal orientation. Porous, open-cell metal foam was used as the column packing. The distillation unit could be operated at extremely low mass fluxes. The operation of the distillation unit was extremely stable, which was achieved thanks to the rigorous control of the fluid flow rates, and heat losses. The heat loss model was regressed based on distillation experiments with total reflux, and the model was used to optimize the temperature of the column shell in order to minimize the heat losses from the column. The volume of the reboiler, the preheaters, and the heat exchangers was minimized with the use of flat channels for intensified heat exchange. The total liquid holdup of the system was less than 40 cm3. The efficiency of the distillation unit was characterized for two binary and one ternary system.

► Accurate control of reflux and reboil flow rates.
► Milli-scale planar distillation unit of 40 cm3.
► Stable operation and suitable for use in a small pilot.
► Rigorous modelling of separation.
► Rigorous calculation of energy balance.