Energy efficient process structure design of LNG/NGL recovery for offshore FLNG plant

FLNG are the floating NG processing plant deployed in the remote marine environment. Their design criterions are different form onshore plant in terms of process safety, storage, compactness, flexibility and simplicity of operation. Considering the FLNG requirements an integrated approach for NG liquefaction and HC recovery is presented. The liquefaction of NG is carried out using commercially tested SMR process and heavier HC are recovered using energy efficient distillation scheme. The main integration highlights between NG liquefaction and recovery modules are the common refrigeration utility and warm feed splitting between two modules. Once the preliminary integrated design is obtained there remain several optimizing parameters that increases the plant efficiency thus, optimization is carried out using process knowledge and modified coordinate decent methodology. Compared to the preliminary design the optimization results show significant energy savings of about 30% in compression energy demand and 20% in columns reboiler duty demand. Conclusively the overall comparison of preliminary and optimized design is made for the given capacity and general recommendations for FLNG design improvement are proposed. (C) 2014 The Authors. Published by Elsevier Ltd.