gas stream and may be processed as described below while three such condensation zones are depicted it will be understood that any number of multiple stage condensation zones is possible the greater the number of condensation zones and the finer the temperature control in each one the more uniform will be the condensed fractions resulting as the cdl components other than the temperature at which each zone is set to condense the structure of each is similar so that only zone b is described in detail herein it being understood that each such zone will have similar structures and function liquid condensed in zone b drains into a chimney tray 58 the chimney tray 58 allows gas to pass through a multiplicity of chimney ducts or tubes while collecting the liquid in the volumetric space above the tray and surrounding the chimney ducts the condensed liquid is drawn away from the chimney tray 58 by means of a pump 60 optionally through a valve 62 and strainer 64 a level meter l and a level control lc maintain the draw rate so as maintain a minimal threshold level at the bottom of zone b the withdrawn liquid is carried to a heat exchanger 68 where it transfers its heat to a coolant fluid that is pumped through the heat exchanger 68 from a source 70 and to which it.