A method 6 wherein {HEAD ~ vapor} employed as a heat source is withdrawn at {TAIL ~ a point} of feed introduction 
is withdrawn at
A method 6 wherein { HEAD ~ vapor } employed as a heat source is withdrawn at { TAIL ~ a point } of feed introduction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