A method 6 wherein {HEAD ~ vapor} employed as {TAIL ~ a heat source} is withdrawn at a point of feed introduction 
employed as
A method 6 wherein { HEAD ~ vapor } employed as { TAIL ~ a heat source } is withdrawn at a point of feed introduction
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH