A method 6 wherein {TAIL ~ vapor} employed as {HEAD ~ a heat source} is withdrawn at a point of feed introduction 
A method 6 wherein { TAIL ~ vapor } employed as { HEAD ~ a heat source } is withdrawn at a point of feed introduction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