Present, state of the art, LNG storage tank use expanded silica and glass wool as insulation materials on, respectively, the tank side and ceiling. When the tank is in operation, these insulations volumes are filled with the natural gas vapors coming from the LNG, at the same pressure as the LNG. This paper presents an innovative solution to improve the thermal performance of this insulation by filling these insulation volumes with argon gas, which has a much lower (40 %) thermal conductivity, with minimal changes in the tank design, as argon, much heavier than natural gas vapors, is simply trapped in these volumes by gravity. The required design changes are respectively negligible (to inject argon in the side insulation spaces using the existing dry nitrogen injection piping) to minute (modification of the suspended ceiling to trap argon gas), making this innovation possible as a retrofit action.
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