(165a) Dynamic Simulation of Natural Gas Liquefaction with Helium Recovery

Natural gas is fastest growing energy economy. Its production and demands are increasing rapidly. Natural gas is transported as liquid over long distances. In 2016, natural gas liquefaction nameplate capacity reached 340 million tonnes per annum (MTPA). By January 2017, over 115 MTPA liquefaction capacity is under construction and 879 MTPA liquefaction capacity is proposed. Natural gas mainly contains methane. Lighter hydrocarbons and other components such as acid gas, mercury, carbon dioxide, water, nitrogen, helium are also present in natural gas. Natural gas pre-treatment is necessary to meet specifications set by standards and customers. The impurities are removed from natural gas before and during liquefaction process.

Helium is one of the precious components with a range of uses. It has limited reserves. The increasing demand and price of helium makes it more important to recover from natural gas. Natural gas reserves are the main resource of helium. Major portions of available helium exist in the United States. Helium can be recovered by processes such as cryogenic separation, adsorption, membrane separation. In this paper, steady-state and dynamic simulations are employed to study the helium recovery together with the natural gas liquefaction process. Sensitivity analysis of the helium recovery performance based on varying operating conditions such as feed composition, flow rate, and natural gas liquefaction temperature are also studied. The optimum operating conditions are suggested for the minimum energy consumption and maximum recovery of grade A helium. The optimization study may provide significant benefits in both LNG and helium productions in North America, where abandon reserves of natural gas are being monetized.