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