Design process of LNG heavy hydrocarbons fractionation: Low LNG temperature recovery

The liquefied natural gas (LNG) includes light hydrocarbons heavier than methane, such as ethane, propane and butane, which not only may increase the calorific values of the natural gas beyond specification limits, but also may have greater market values. During the gasification of the LNG, the energy invested in it during liquefaction process may be recovered and re-used. This paper relates to two regasification processes for separating natural gas liquids from liquefied natural gas using the low LNG temperature to produce natural gas meeting pipeline or other commercial specifications. From the two processes studied, the fractionated methane-rich stream is pressurized to pipeline pressure by pumps instead of compressors and the liquefied ethane, propane and butane are obtained directly at atmospheric pressure. Among the processes studied, the low pressure process sounds economically attractive with a saving in TAC of 4.6% over the high pressure process; however the high pressure process is more preferable for the cases where the space is limited.