Estimation of the design pressure of a prismatic LNG storage vessel

• Design pressure consists of the vapor pressure and liquid pressure for type B prismatic vessel.
• Offset of the increase of vapor pressure by the decrease of the liquid pressure during voyage.
• Dynamic simulaon is conducted by a commercial software gPROM developed by PSE.

This study proposed a method of estimating to design pressure in a prismatic storage vessel for liquefied natural gas. The estimation of the design pressure refers to the IGC Code that provides the international standards for storage of liquefied gases in bulk. The estimation of the design pressure was a basic step to scheme a storage vessel. The design pressure resulted from the vapor pressure and the maximum liquid pressure. The liquid pressure was calculated from the effect of gravity and the acceleration applied to the center of gravity of the liquid. Loading conditions of up to 98% were considered in the calculation of the maximum liquid height. The heat ingress warmed the LNG, which caused it to exceed its boiling temperature. Calculation of the vapor pressure was described by the material and energy balance equations. Dynamic simulation about the pressure behavior was conducted by commercial software. The vapor pressure affected by heat ingress from surrounding conditions was calculated with time variations.