Design and analysis of LNG cold energy cascade utilization system integrating light hydrocarbon separation, organic Rankine cycle and direct cooling

To effectively recover the cold energy released in the liquefied natural gas (LNG) regasification process, this paper constructs a novel LNG cold energy cascade integrated utilization system. In the system, the LNG cold energy in low temperature zone is used for light hydrocarbon separation (LHS), and the remaining cold energy is divided into two parts. One part is used for organic Rankine cycle (ORC) as well as data center cooling (DCC), and the other part is used for cold warehouse cooling (CWC). The thermodynamic and economic analysis of the system is carried out in detail, and the multi-objective optimization based on NSGA-II is implemented to investigate the optimal performance. The results show that the net power output of the system is 4259.72 kW, much larger than that of the LNG cold energy single utilization system for LHS in reference, and the cold energy for data center and cold warehouse is equivalent to saving 12685.87 kW electric energy. Furthermore, the revenue of the system in 20 years is 2.9982 × 109 $, more than that of the reference system. Through the net present value analysis, it is found that the system is more sensitive to the ethane price than to electric price.