Embodiments of the basic method where vapor only, liquid only, or both liquid and vapor are withdrawn from and returned to {HEAD ~ the phase} contacting {TAIL ~ region} of the distillation system are considered 
Embodiments of the basic method where vapor only , liquid only , or both liquid and vapor are withdrawn from and returned to { HEAD ~ the phase } contacting { TAIL ~ region } of the distillation system are considered
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH