Gas Absorption with <scp>First‐Order</scp> Reaction in a Packed Tower

This chapter presents rigorous surface renewal and film models for gas absorption accompanied by a first-order chemical reaction in a countercurrent packed tower and compares their predictions. Analytical solutions of the models, which include both gas- and liquid-side mass-transfer resistances, are derived for predicting the bulk gas-phase and dissolved-gas liquid-phase concentration profiles along the height of the tower. The analysis differentiates between the rate of absorption of the solute gas at the gas–liquid interface and the rate of transfer of dissolved gas to the bulk liquid and derives approximations for gas- and liquid-phase control of mass transfer. Three sample gas–liquid systems with widely different solubility and mass-transfer limitations are chosen for illustrative calculations which reveal that the film and surface renewal models, although radically different qualitatively, are in excellent agreement as regards quantitative prediction of the tower gas- and liquid-phase concentration profiles for different values of the Hatta number.