{HEAD ~ The carbon dioxide recycle stream} is combined with {TAIL ~ the feed} to the carbon dioxide PSA unit 
{ HEAD ~ The carbon dioxide recycle stream } is combined with { TAIL ~ the feed } to the carbon dioxide PSA unit
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH