Cryogenic storage system

Claim 1

IN A CRYOGENIC STORAGE SYSTEM FOR A DENSE GAS, THE COMBINATION COMPRISING AN INNER PRESSURE VESSEL FOR HOLDING SAID DENSE GAS; A SECOND PRESSURE VESSEL FOR CONTAINING A MORE EXPENDABLE CRYOGENIC GAS IN THE LIQUID STATE, SAID SECOND PRESSURE VESSEL SURROUNDING SAID INNER PRESSURE VESSEL; SUPPORT MEANS OF LOW THERMAL CONDUCTIVITY MATERIAL FOR HOLDING SAID FIRST AND SECOND VESSELS IN SPACED RELATIONSHIP TO ONE ANOTHER; AN OUTER SHELL SURROUNDING SAID SECOND PRESSURE VESSEL IN SPACED APART RELATIONSHIP THERETO, AND PROVIDING A VACUUM SPACE THEREBETWEEN; A HEAT-CONDUCTIVE SHIELD SURROUNDING SAID SECOND PRESSURE VESSEL WITHIN SAID VACUUM SPACE BETWEEN SAID SECOND PRESSURE VESSEL AND SAID OUTER SHELL; A VENTING CONDUIT FLUIDLY COMMUNICATING WITH SAID SECOND PRESSURE VESSEL AND PASSING THROUGH SAID HEAT CONDUCTIVE SHIELD AND THE OUTER SHELL FOR VENTING VAPORIZED CRYOGENIC GAS, SAID CONDUIT BEING DISPOSED OVER A FIRST PART OF ITS LENGTH IN HEAT-EXCHANGING ENGAGEMENT WITH SAID SECOND PRESSURE VESSEL AND OVER ANOTHER PART OF ITS LENGTH IN HEAT-EXCHANGING RELATIONSHIP WITH SAID HEAT CONDUCTIVE SHIELD; AND A THROTTLING VALVE IN SAID VENTING CONDUIT FOR REDUCING THE PRESSURE AND TEMPERATURE OF THE VAPORIZED CRYOGEN WHICH IS VENTED THROUGH SAID CONDUIT WHEREBY THE HEAT CONDUCTIVE SHIELD AND THE SECOND PRESSURE VESSEL ARE SUBJECT TO VAPOR COOLING BY THE FLOW OF VAPORIZED REFRIGERANT CRYOGEN THROUGH THE HEAT-EXCHANGING VENTING CONDUIT.