SO2 removal by seawater in a spray tower: Experimental study and mathematical modeling

In this article, the reactive absorption of SO2 by seawater is studied in a spray tower experimentally and mathematically. The liquid film formation on the tower wall is implemented in the model and measured experimentally at different operating conditions. The effect of liquid to gas flow rate, initial SO2 concentration in gas phase and initial gas temperature on SO2 removal efficiency is examined. Regarding the importance of liquid droplets hydrodynamics and its effect on the performance of the equipment, the required differential equations for predicting the trajectory and local velocity of droplets are also developed based on the nozzle and spray characteristics and solved simultaneously with other governing equations. In order to survey the effect of nozzle type on removal efficiency, two different types of nozzles are examined. Semi-empirical correlations are proposed for two different nozzles by using experimental data and droplets hydrodynamics model, to predict the amount and the variation of liquid film mass flow rate on the spray tower wall. Results indicate that neglecting the liquid film formation leads to an average of 23% error in predicting the removal efficiency when nozzle type 1 is used, while the calculated error of model by considering the film formation is reduced to 4%. By implementation of droplets hydrodynamics model and applying a modified thermodynamics model for predicting the behavior of the existing chemical reactions, the capability of the spray tower model in predicting the SO2 removal efficiency is enhanced. (c) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.