chemical engineering research and design 1 0 9 ( 2 0 1 6 ) 180–189 Contents lists available at ScienceDirect Chemical Engineering Research and Design journal h om epage: www.elsevier.com/locate/cherd SO 2 removal by seawater in a spray tower: Experimental study and mathematical modeling Sh. Darake, M.S. Hatamipour ∗ , A. Rahimi, P. Hamzeloui Chemical Engineering Department, College of Engineering, University of Isfahan, Hezar Jerib Blvd., 81746-73441 Isfahan, Iran a r t i c l e i n f o Article history: Received 14 May 2015 Received in revised form 26 November 2015 Accepted 30 November 2015 Available online 25 January 2016 Keywords: SO 2 removal Seawater Spray tower Flue gas desulfurization (FGD) Mathematical modeling a b s t r a c t In this article, the reactive absorption of SO 2 by seawater is studied in a spray tower experi- mentally 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 liq- uid to gas flow rate, initial SO 2 concentration in gas phase and initial gas temperature on SO 2 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 noz- zle 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 noz- zles 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 neglect- ing 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 SO 2 removal efficiency is enhanced. © 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction Recently, the international committees have adopted several restrictions for depletion of the released SO 2 from indus- tries (Vidal et al., 2007). In the past few decades, studies have focused dramatically on the flue gas desulphuriza- tion (FGD) process. Meanwhile, different equipment such as venturi scrubbers, spray towers, tray towers, packed beds (Bandyopadhyay and Biswas, 2006, 2008; Gamisans et al., 2002), and membrane technology (Sun et al., 2008) have been studied for FGD process in a vast range. Abbreviations: FGD, flue gas desulfurization; ppm, parts per million by volume; ppt, parts per trillion. ∗ Corresponding author. Tel.: +98 313 7934047; fax: +98 313 7934031. E-mail address: hatami@eng.ui.ac.ir (M.S. Hatamipour). The most common method for FGD is scrubbing the pol- luted gas through alkali solvents like urea, dilute NaOH, limestone slurry, NaCl solution, water, and seawater (Barbooti et al., 2011; Bokotko et al., 2005; Jeong and Kim, 1997). Accord- ing to searches in this respect, a few studies were conducted on using seawater as an alkali absorbent for SO 2 removal. Sun et al. (2008) studied SO 2 absorption by seawater in a hollow fiber membrane contactor and found that the mass transfer coefficient in seawater is about double the mass trans- fer coefficient in the NaOH solution content with a pH of 8.35. http://dx.doi.org/10.1016/j.cherd.2015.11.027 0263-8762/© 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.