NL261306A - - Google Patents

Abstract

900,268. Storing liquefied gases. CONCH INTERNATIONAL METHANE Ltd. Jan. 9, 1961 [May 27, 1960]. No. 795/61. Class 8(2). [Also in Group XXXIII]. A thermally insulated structure, for example forming part of a tanker, for the storage and transportation of a cold liquid having a boiling temperature considerably below the ambient temperature, e.g. liquefied natural gas comprises a primary container 22 of large capacity mounted within a metal housing 40, e.g. the inner hull of the tanker, which lined adjacent its inner surface with a thermal insulation, the latter comprising the combination of a primary layer 42 of a porous insulating material, e.g. balsa wood or foamed plastic material, mounted on the wall of the housing 40 and having the ability to resist penetration of the cold liquid in the event of failure of the container 22 and a secondary layer 50 of a thermal insulating material, e.g. diatomaceous earth or glass wool fibres, incapable of resisting penetration by the cold liquid and positioned inwardly of and supported adjacent to the primary layer 42. The primary layer 42 may have an interconnected pore structure if it is sealed to the housing 40 and if the vapour permeability of the pores in the vertical direction is less than the amount of vapour made available by the cold liquid penetrating the insulation; the entrapped vapours in this case provided an insulation layer between the housing 40 and the penetrating liquid. Alternatively, the primary layer 42 may have a disconnected pore structure so that the cold liquid will be unable to penetrate into the layer. Inwardly of the secondary insulating layer 50 there is provided a protective wall of plywood panels 44 which may be supported on wooden struts 46 fixed to the layer 42 or extending therethrough and fixed to the housing 40. The container 22 is supported upon a flooring 52 having an upper layer of hard wood 54, e.g. plywood, and where a plurality of containers are disposed in the inner hull of a tanker they are secured by top and bottom keys fitting slidably within associated keyways to stabilize the position of the containers while allowing them to contract and expand, Fig. 3 (not shown). The inner hull of the tanker is spaced from the outer hull and fluid is circulated therebetween to minimise transfer of cold to the outer hull in the event of failure of the insulation. In a modification, Fig. 2 (not shown) a wall of plywood panels is mounted by means of firring on the housing 40, the primary layer of insulating material being sealed to the inner side of the panels and the space between the housing 40 and the panels being filled with fibrous or particulate insulating material. The inner surface of the primary insulating layer is protected by further panels of laminated paper, metal or plywood coated with synthetic resin against which is located the secondary insulating layer faced with a further wall.