Decarbonization and enhancement of LNG cascade cycle by optimizing the heat rejection system, hourly evaluation

This study is motivated by global directions towards reducing carbon emissions. LNG is a very energy intensive industry and improving its efficiency is an essential area of study. LNG process is sensitive to cooling media, so conventional air cooling is replaced by proposed water cooling with a cooling tower. Aspen Hysys V11 is used for simulating the base and proposed systems in this study. The proposed water-cooling system is simulated and compared with the conventional air-cooling system in Alexandria, Egypt as the base location of the study, at a single simulation point. For more data refinement, hourly temperature records are used for simulation and total annual performance is calculated based on 8784 simulation points, which achieved a total year improvement of 3.98% reduction in SPC, fuel gas and CO2 emissions and 7.21% reduction in annual propane consumption. To assess the suitability of the system in different climates, four different locations are assessed: Nigeria, Qatar, Egypt, and Russia. Performance is measured throughout the year on hourly calculations. Results revealed that power reduction up to 4.26% can be achieved based on total year performance. The power reduction achieved is 1.24%, 1.6%, 3.98%, and 4.26% for Russia, Nigeria, Egypt, and Qatar, respectively. •Comparing water and air cooling based on hourly data.•Annual performance assessment of LNG Cascade Cycle.•Total annual performance improvement up to 4.26%.•Assessing different locations with different climate conditions.•Locations with lower RH% achieving higher performance.