Design Of LPG Tank And Temperature Distribution Of Its Structural Support

This article is in the joint training project of Dalian University of Technology and SOE, which gave much help during the project.With the increasing trade of LPG (liquefied petroleum gas), the market demand for LPG vessels also further expands. As The main equipment of liquefied gas, LPG tank is used for storage and transportation of the liquefied petroleum gas, ethylene and VCM gas. According to different liquefaction conditions,it is divided into three kinds:compression (smaller loading capacity), the semi-cold semi-pressure type (larger loading capacity) and cooled (large load).As a high-tech, high value-added marine equipment, the design and manufacturing of the tank is of great difficulty and is now only mastered by a small number of domestic and foreign companies and organizations.The main work of this paper is based on the ship oriental liquefied gas tanker requirements and the corresponding tank design requirements. And calculated the parameters of tank structural support using mathematical model and finite element model.Last the temperature distribution of tank-ship structure located in different places is calculated and checked, which results in the conclusion that the structure of the ship is merely effected by the low temperature of tank.First, study on the theory of tank design is made according to previous designing experience.. According to the IGC and USCG rules and referring to the specification approved by GL, the AD, BS and ASME and other pressure vessel code. The design and calculation of single tank and bilobe tank structural is made with the help of LPG tank design software developed by Nantong Sinopacific ocean-engineering company and Shanghai Jiaotong University. The whole work is divided into the following parts:thickness calculation and checking, inside components calculation and checking, sloshing analysis and opening design and checking. Then preliminary design drawings are made according to the parameters checked by previous parts.Next,the parameter of the thickness of the insulation on the structural support is calculated by a mathematical model,and used Patran to build a finite element models to verify the results,which came out with nearly the same results, and all this proved that the correctness of mathematical model as well as the calculation of thickness of insulation. Finally, the temperature distribution of tank-ship structure located in different places is calculated and checked requested by GL, which result in the conclusion that the structure of the ship is merely effected by the low temperature of tank.Limited by the short time of developing and relating conditions, theory of design is still not perfect enough, which needs further research to reach the goal "safe, reliable and economical". On the other hand, corresponding rules and should catch up with the paces of theory and practice and need self-improvement to follow the advancement of LPG tank design.