A process 15 wherein said furnace is heated by {TAIL ~ radiant burners} that are fed with {HEAD ~ preheated air} 
A process 15 wherein said furnace is heated by { TAIL ~ radiant burners } that are fed with { HEAD ~ preheated air }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD