The drop size distribution in a spray tower was obtained by means of the photographic technique with air and water as the experimental media. The effects of spray flux and superficial gas velocity on Sauter mean diameter (SMD) of droplets at different heights of the absorption zone were investigated. The drop size distribution was analyzed theoretically. Dense droplets assembled at the top of the tower; on the contrary

droplets became sparse at the bottom. Small and uniform droplets could be formed in the falling process. With increasing spray flux

the SMD of droplets increased at the top of the tower

while decreased at the middle and lower zones. Average droplet diameter decreased with increasing superficial gas velocity. Theoretically

the decrease of droplet size was mainly accounted for by collision and breakup among droplets

which was primarily caused by diversity of droplet diameters. Dimensionless correlation of SMD was proposed

and the calculation results were in good agreement with the actual data. The specific surface area of spray tower with collision and breakup among droplets was about 70% larger than that without collision and breakup.