A novel process configuration for co-production of NGL and LNG with low energy requirement

Abstract

In this study a novel integrated process configuration for NGL/LNG production is introduced and analyzed. This configuration uses two mixed refrigerant cycles in order to supply the required refrigeration for production of both NGL and LNG. The results showed that not only liquefaction efficiency of the process is considerable (0.414kWh/kg LNG) but also it can recover the ethane (from a rich typical feed gas (methane 75%, and heavier hydrocarbons 23%)) higher than 93.3%. Four multi stream heat exchangers were utilized, the composite curves of them shows that they have been designed optimally. These heat exchangers perform their role for both targets simultaneously due to the integration of the NGL and LNG processes. Even though this point increases their size, but the total capital costs of the plant decrease. This process can be used for large LNG plants in the natural gas refineries. It can also be said that the overall efficiency will be higher for the leaner feed gases.