Proposed method for design optimization of LNG tanks based on the arrangement of thermal insulation panels

Abstract

During the building of an LNG tank, a thermal insulation panel, hereafter referred to as a “panel,” is installed on the inner wall to insulate the tank from external conditions. The inner wall of the LNG tank can experience deformations, leading to the panel becoming inclined and twisted, making it susceptible to damage and reducing its insulation effectiveness. To address this challenge, a common practice involves placing wedges at each corner of the panel between the inner tank wall and the panel, and then filling the resulting gaps with a mastic rope. However, this extensive use of mastic ropes to mitigate panel inclination and twisting is a costly solution.The primary objective of this study is to optimize the overall use of mastic ropes for enhanced tank insulation. This optimization is achieved by determining the ideal panel installation height, which is dependent on factors such as the wedge height, as well as panel inclination and twisting. These parameters serve as the objective functions and constraints for optimization.To validate the effectiveness and feasibility of the proposed method, tests were conducted by applying the proposed method to cover the inner wall of an LNG tank with insulation panels. The study considered four cases, each focusing on different objective functions related to the economic feasibility and safety of LNG tanks, and compared the results. In the most cost-effective solution, the total use of mastic ropes was reduced by approximately 42% compared to the conventional manual design. Furthermore, safety-related solutions demonstrated improved safety levels compared to the manual design, with only a marginal 0.1% change in the total use of mastic ropes. Lastly, in cases where both economic feasibility and safety were considered, improvements were observed in both aspects compared to the manual design.