Cryogenic Air Separation Process Integrated with Cold Utilization of Liquefied Natural Gas: Design, Simulation and Performance Analysis

Air separation processes are complex and highly energy-intensive. In ASU, the majority of the energy loss happens during air compression. This wastage of energy is utilised for heating LNG. An LNG regasification station is where LNG vessels will eventually halt. Here, the liquefied natural gas is converted back to gas and supplied to the distribution and transmission infrastructures. Cryogenic LNG has a high potential for cold energy recovery throughout the regasification process. This research examines a novel air separation unit (ASU) design that is combined with LNG's direct expansion cycle (DEC). The study is novel in a way that a performance of an ASU combined with a DEC is analysed through process simulation in Aspen Hysys (12.1) for a 3993-kW power plant. The results of this investigation show that the specific energies needed for the generation of high purity oxygen and high purity nitrogen are, respectively, 0.10 kWh/kg and 0.32 kWh/kg. Additionally, 3993 kW of energy are saved in the system as a result of an adequate system combination of other subsystems and LNG vaporisation. For the system's primary components, exergy destruction and efficiency have been computed. Additionally, sensitivity analysis is performed to investigate the impacts of critical parameters. In conclusion, to provide the required power for operation and eliminate unnecessary power inputs, a cryogenic ASU is coupled with an LNG-DEC power cycle. Overall, the LNG industry should consider integrating air separation processes and LNG as a viable and appealing option. By using less fossil fuels, it also increases the sustainability of the process.

Automated summary

Air separation processes in LNG industry can be combined with LNG's direct expansion cycle (DEC) to recover cold energy and improve energy efficiency. This novel ASU design saves energy by utilizing the energy loss during air compression for LNG heating. This integration of air separation processes and LNG offers a sustainable and appealing option for the LNG industry.