Dynamic measurement of liquid‐phase mass transfer coefficient and significance on the SO2 absorption rate

Abstract

AbstractLiquid‐phase mass transfer coefficient is important for characterization of gas–liquid reactors and relevant to the modelling of gas absorption rate. Both direct and indirect methods have been used to obtain this coefficient. However, these methods have not been compared on the same basis. Liquid‐phase mass transfer coefficients were measured in three ways—(a) CO2 absorption into water, (b) SO2 absorption into 1 kmol m−3 of HCl, and (c) O2 absorption into Na2SO3—and then normalized to the coefficient for SO2. Based on transient experiments, the normalized values for liquid‐phase mass transfer coefficient obtained from three methods are in turn of . The fluxes of SO2 predicted from three methods were further compared with the experimental values measured in SO2‐NaOH system. The fluxes predicted from agreed well with the experimental values, whereas those from and were significantly lower or higher. Therefore, the liquid‐phase mass transfer coefficient is preferably obtained from the targeted gas. Modelling on the flux of SO2 demonstrates the transition of controlling regions against pH. At pH above 4, the gas side resistance is larger than the liquid side, whereas at pH below 4, the gas side resistance is smaller than the liquid side.