Abstract
The traditional choice of insulation material for offshore LNG transportation with type C independent tank was polyurethane foam (PUF). However, aiming to further cut down the insulation cost and spare additional arrangement space, the requirement of searching for the alternative materials still exists. Polyisocyanurate board (PIRB) and silica aerogel blanket (SAB) are chosen as candidates in this study since these two materials have been proved to be available in other fields. Despites their advantages, the seams and joints due to the specific installation techniques for PIRB and SAB could be the causes of potential defects when transporting cryogenic liquid. In this paper, the comparative study of three materials associated with their specific installation techniques was conducted to discuss if PIRB and SAB are available for offshore LNG transportation. Therein, the insulation performances were investigated through the evaporation experiment of LN2 with a 1.5 m3 type C experimental tank. The equivalent conductive model was adopted in the numerical analysis with finite element method (FEM) to determine the temperature field of insulation and the absorbed heat from the LN2 evaporation. It is proved that three types of insulation materials are well behaved and available for transporting cryogenic liquid. In respect of the thermal resistance, the ranking of three types of insulation materials is: SAB, SPF and PIRB. Higher thermal resistance of insulation leads to thinner thickness and additional arrangement space in the cargo hold, and more ship construction cost can be cut down due to the possible scaling down of ship dimensions. However, from the perspective of insulation material cost, the cost reduction due to the insulation thickness decrease is not significant as the tank continually scales up, and it is more practical to apply SPF or PIRB on a full-scale type C independent tank.
Published Version
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