in the description of the figures the same numbers will be used throughout to refer to the same or similar components not all pumps valves and other control elements have been shown in the interest of simplicity in fig1 a typical system 10 for revaporizing a cryogenic liquid according to the prior art is shown in this system a first heat exchanger 12 typically having extended heat exchange surfaces is used along with a second heat exchanger 14 which also typically has extended heat exchange surfaces a cryogenic liquid is injected through an inlet line 16 this liquid may be passed to one or both of vessels 12 or 14 however it is typically passed to only one of vessels 12 or 14 at a given time for instance the cryogenic liquid may be passed through line 18 and valve 20 into heat exchanger 12 and vaporized by heat exchange with air and passed as vaporized gas through a line 38 to a line 40 for recovery air is passed through heat exchanger 12 naturally by gravity or more typically by a forced air system shown schematically as a fan 26 with the air being exhausted as shown by arrows 30 after a period of time the air which typically contains some humidity will precipitate water this water typically freezes on the heat exchange surface in the lower portion of heat exchanger 12 at this point the cryogenic liquid is rerouted through line 22 and valve 24 to heat exchanger 14 for vaporization for a period of time so that heat exchanger 12 may thaw this thaw may be accomplished for instance by use of a continued flow of ambient air through heat.