Analysis of simultaneous heat and mass transfer in the stripping of methanol from aqueous solutions

Abstract

Methanol was stripped from a dilute aqueous solution under countercurrent conditions in a pilot scale packed tower, using a gas prepared by mixing air and steam in various proportions. A mathematical model involving simultaneous heat and mass transfer was developed to describe the situation; this model included consideration of fog formation, column pressure drop and heat loss to the environment. Results from the model, including axial profiles for liquid temperature and liquid phase methanol concentration, were reasonably consistent with experimental measurements. Practical use of the model is presently limited by unresolved problems with sensitivity and occasional instability of the analysis. Nonetheless, the mechanism developed may form the basis for an improved model to describe complex situations involving stripping/absorption with significant effects. Pressure drop through the packing was an important consideration in the theoretical analysis of the experimental results.On a extrait le methanol d'une solution aqueuse diluie, dans une colonne garnie a I'Cchelle pilote avec alimentation