{HEAD ~ An apparatus} 30, wherein said mechanism for regenerating {TAIL ~ the first adsorbent bed} comprises a mechanism for passing a regeneration gas through the bed 
{ HEAD ~ An apparatus } 30 , wherein said mechanism for regenerating { TAIL ~ the first adsorbent bed } comprises a mechanism for passing a regeneration gas through the bed
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH