What are the reasons why lng cylinders are not insulated? The lng gas cylinder in this question is lng storage tank. Besides the distribution of vertical, horizontal, sub-parent and other application forms, the form of storage tank is divided into mobile storage tank and fixed storage tank. Such as gas station, gasification station and other storage tanks are fixed, lng vehicle, lng ship for mobile.
The mobile or small stationary cryogenic storage tank for transport is of double structure. The tank stores cryogenic liquid under pressure and low temperature of medium. The material of the inner liner is generally made of low temperature resistant alloy steel, and the outer shell is the protective layer of the inner liner. A certain distance between the tanks is maintained to form an adiabatic space, which can withstand the gravity load of the inner tank and the medium and the vacuum negative pressure of the insulation layer. The shell is not exposed to cold temperatures and is made of container steel. The insulation layer is mostly filled with pearlite and vacuumed. The evaporation rate of cryogenic tanks is generally less than 0.2%.
Elastic felt and perlite are used as the main insulation layers for the sandwich insulation of some large lng storage tanks used for liquefaction, and the elastic felt can be used as the insulation of lng storage tanks alone. The insulation layer should meet the requirement of -162℃ for low temperature application. Once the insulation layer is wet or damaged, it is easy to produce condensation or frost, thus affecting the insulation effect of the cylinder.
Obviously, the reason for the non-insulation of lng gas cylinder tanks may be the damage of vacuum layer or insulation layer, which leads to air flow condensation and reduces the insulation performance. At present, the cooling materials used in liquefaction of large storage tanks are mostly Uetersen elastic felt. The construction is generally combined with perlite or the elastic felt is used alone for the storage tank cooling application.