Abstract
An investigation has been carried out, on a pilot plant scale, into the factors affecting the hydrodynamic behaviour, the mass transfer efficiency, the liquid residence time and the extent of liquid mixing in a two sieve tray distillation column. Hydrodynamic behaviour was investigated as a function of column operating conditions and column geometry; the results of this investigation have been reported in the form of correlation equations suitable for use in distillation column design. The liquid residence time and extent of liquid mixing in the column were measured using a dye injection technique and were investigated as a function of column operating conditions and system geometry. The injection and detection systems necessary to this technique were .constructed in the College workshops. Use of an analytical expression for the output signal has enabled the results of this study to be presented in the form of a transfer function for the apparatus. The gas-liquid system chosen for the mass transfer study was the air-aqueous glycerol-Oxygen system; because of the low solubility of oxygen in aqueous glycerol solutions this system may be regarded as entirely liquid phase controlling. Mass transfer efficiencies measured using this system may therefore be regarded as pure liquid phase efficiencies. Special features of the apparatus necessary for this investigation include an efficient method of injection of the oxygen into the liquid system and a new technique which enabled continuous measurement of the oxygen concentration of the liquid at any point on the tray. The mass transfer efficiency has been successfully related, to the hydrodynamic behaviour, the liquid residence time distribution and extent of liquid mixing in the column for the range of operating conditions and system geometry used in the experiments.