area in one embodiment oriented perpendicular to the spray tower 20 vertical axis spray nozzles 40 are designed and provided to develop a pre determined mean droplet size having a terminal velocity from about sixty 60 percent to about ninety five 95 percent of the local superficial upward gas velocity the flow of which is indicated by reference arrows 50 thus in the upward flowing gas stream the droplets fall relative to a fixed reference point along the vertical axis indicated along centerline 52 at a rate from about five 5 percent to about forty 40 percent of their terminal velocity of course in any spray nozzle system some droplets are generated in a spectrum of droplet sizes that includes droplets larger and smaller than the mean preselected size however very small droplets entrain in the upward flowing gas stream and leave the semi fluidized section 48 if such droplets do not impinge on the containment vessel interior walls 54 or other droplets 43 they are carried upward into the coalescing section 56 above the spray nozzles 40 however large droplets and those that become large droplets fall growing as they combine with other droplets and eventually pass out of the semi fluidized section and into the fluidized section other droplets 58 impinge on the tower walls and then flow down into the contact water reservoir 74 initially substantially all small water droplets 43 of preselected size are suspended at the top of the fluidized section 30 and do not fall down through the section until they agglomerate with other particles by increasing their size droplet 43.