Storage vessel for liquefied gas

Claim 1

A storage vessel for a liquid adapted to be maintained normally at a temperature below about 30°K, said vessel comprising: an inner shell defining a chamber receiving said liquid; a radiation shield specedly surrounding said inner shell and defining an inner compartment therewith; an outer shell spacedly surrounding said radiation shield and defining an outer compartment with said radiation shield; a mass consisting of pulverulent insulating material free from metal particles filling said inner compartment; a mixture of pulverulent insulating material and metal powder filling said outer compartment, the proportion of metal powder in said mixture being substantially 15 to 30 percent by weight, said insulating material being perlite and said metal powder being aluminum or copper; means for cooling said radiation shield and including tubes lying in said outer compartment and extending along and in heat-exchanging relationship with said radiation shield, and means for passing a deep-cooled fluid through said tubes, the distance between said outer shell and said radiation shield and the distance between said radiation shield and said inner shell being in a ratio of about 2:1; means for evacuating said inner compartment; and means for exacuating said outer compartment.