Composite insulation for cryogenic vessel

Claim 1

A single wall cryogen storage vessel having means to substantially reduce the transfer of thermal energy between an outside surface of the vessel and an environmental source, said means comprising: a closed cell foam insulating member secured to said outside surface, said foam insulation reducing the transfer of thermal energy by gaseous convection in an earth type atmosphere; a first reflective metallic coating applied to and sealing the outer surface of said closed foam insulating member to form a radiation shield for dispersing radiant thermal energy of an environmental source away from the storage vessel; a first reflective shield separated a predetermined distance from said metallic coating by a thermal non-conductive spacer, to form a purge chamber surrounding the closed foam insulating member; a second reflective shield separated a predetermined distance from said first reflective shield by a thermal non-conductive spacer to form a cooling chamber adjacent said purge chamber, said first and second reflective shields having a reflective metallic coating on their internal and external surfaces for dispersing radiant energy; a network of cooling lines located between the first and second reflective shield operatively connected to said pressure vessel, said cooling lines being adapted to carry refrigerant for dissipating of thermal energy caused by radiant energy diverted by the reflective metallic on the surfaces of the first and second reflective shields; a laminated member having a reflective metallic coating secured to an insulating backing secured to the external surface of said second reflective shield, said laminated member initially uniformly dispersing radiant energy from said environmental source, said reflective metallic coatings on the closed foam insulating member, first reflective shield, second reflective shield and laminated member being substantially equal and thereby uniformly reducing the transfer radiant energy therebetween; and a flexible membrane surrounding said storage vessel and connected to said purge chamber, said membrane being connected to a source of low thermal conductive gas to maintain the closed cell foam in an inert condition in an earth type atmosphere to reduce conductive thermal transfer between the storage vessel and said first reflective metallic coating, said low thermal conductive gas in the purge chamber dissipating radiant thermal energy diverted to the purge chamber by the reflective coating on said first reflective shield, said flexible membrane being ruptured by the low thermal gas upon transfer of the storage vessel to a vacuum environment to permit the low thermal gas to escape from the purge chamber and a vacuum be established in the purge chamber to isothermally isolate the cooling chamber from the closed foam insulating member.