Plate efficiency with chemical reaction—absorption of Carbon dioxide in Monoethanolamine solutions

Abstract

Abstract The effect of chemical reaction on plate efficiency has been given little attention in the determination of bubble‐plate efficiencies, although it is of importance in many operations. A typical example is the absorption of carbon dioxide in monoetnanolamine solutions. The over‐all Murphree gas‐phase plate efficiency can be shown to be a function of K g ( A / V ) where A / V is the interfacial surface area formed per tray per unit volume of gas. In order to evaluate variations in tray efficiency due to factors influencing K g , data available in the literature for the absorption of carbon dioxide in monoethanolamine were considered. These showed that the liquid film was controlling and that for a packed column at constant liquid rate the absorption coefficient could be satisfactorily expressed by an equation that resembles somewhat equations which have been developed for the effect of rapid secondorder reactions on k L . However, the observed effect of carbon dioxide partial pressure in the gas is not so great as the theoretical equations would predict. By use of the equation mentioned above to predict K g , satisfactory correlation of observed plate efficiencies is obtained for a commercial column over a considerable range of conditions. It appears that the correlation can be extended to other pressures, flow rates, and column designs by an evaluation of the effect of these variables on A / V and K g .