Liquid hold-up and scale change in distillation.

Data of static and operative hold-up are determined by distillation at tota l reflux in a structured gauze packing column of the mixture cyclohexane- m ethyl benzoate and ethanol-methyl benzoate. Dependence of hold-up on F-fact or has the same shape as variations suggested by severals correlations for pilot scale and similar equations are proposed. As a result of this depende nce and the relationship between hold-up and effective area, this one may b e considered a constant when flow increases and the change in the efficienc y of laboratory packings can be explained.