Contact surfaces are arranged inside the fluid bed whose total area is the same as up to 500 times the area of {HEAD ~ the approach flow bottom} of {TAIL ~ the fluid bed} 
of
Contact surfaces are arranged inside the fluid bed whose total area is the same as up to 500 times the area of { HEAD ~ the approach flow bottom } of { TAIL ~ the fluid bed }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL