{TAIL ~ The primary gas flow} is subjected to a final treatment stage similar to {HEAD ~ the initial heat exchange treatment} 
{ TAIL ~ The primary gas flow } is subjected to a final treatment stage similar to { HEAD ~ the initial heat exchange treatment }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD