FLOW PHENOMENA IN STAGED AND NON
In Staged and Non Staged Distillation Equipment, there can be two types of liquid flow that may either assist or impede heat and mass transfer; a macro and micro flow phenomena. The macro flow phenomena deals with the mixing of the continuous liquid phase in large divisions of the column. If inferior mixing is present, this can lead to differing concentrations of the heavy and light keys within the column even on the same stage.
The micro flow phenomenon is based on the point flow, the liquid stream not fully mixed in small sections of the column leading to loss in stage efficiency. In non-staged equipment the down coming liquid can coalesce into larger flow streams, reducing the mass transfer with the rising vapor. In staged equipment, the eddy diffusion on an individual tray can lead to inactive zones where no separation occurs.
Two case studies will be presented which deal with inferior macro and micro flow phenomena. An inferior macro / micro phenomenon cannot be detected by utilizing McCabe-Thiele or simulation software in the conceptual stages. The macro / micro flow phenomena must be reviewed in the mechanical drawing review stage to eliminate the possibility.