Process integration of light hydrocarbon separation and hydrate-based desalination for efficient and practical LNG cold energy recovery

Abstract

Liquefied natural gas (LNG) regasification occurs over a wide temperature range, and LNG cold energy released from regasification cannot be fully utilized in a single process. Various studies have integrated individual processes to improve LNG cold energy utilization. However, each process has different temperature requirements, and it is challenging to integrate the geographical environment. This study presents a novel LNG cold energy multi-utilization process by integrating light hydrocarbon separation (LHS) and hydrate-based desalination (HYD) for efficient and practical LNG cold energy recovery. In the proposed process, light hydrocarbons in LNG are separated from LHS, which requires cryogenic energy. The remaining LNG cold energy is then utilized for HYD, which requires an operating temperature of 1 °C. Energy, exergy, and techno-economic analyses were compared to the base case, where cold energy was only used for desalination. The results show that a more efficient energy utilization process was achieved by reducing the exergy loss by 16.47 %. High-value materials could be recovered, such as liquefied ethane and liquefied petroleum gas, high-purity methane gas, and pure water. Despite additional equipment costs attributable to LHS, the net annual revenue based on the generated products was 6.66×107 USD/yr, with a payback period of 6.66 yr.