Krill-Herd-Based Investigation for Energy Saving Opportunities in Offshore Liquefied Natural Gas Processes

For offshore natural gas liquefaction operation, the single mixed refrigerant process is considered as one of the best and most suitable processes. However, multivariable nonlinear thermodynamic interactions among operating conditions and flow rates of mixed refrigerant ingredients lead to energy losses, which ultimately contributes to high energy consumption for liquefied natural gas production. The present work investigates the energy saving opportunities in the single mixed refrigerant liquefaction process through “krill-herd” strategy which is based on the biological flocking (herding) behavior of individual krill. To find the energy saving opportunities, the krill-herd approach effectively reduced the exergy losses of the compression units and cryogenic heat exchanger up to 18.6 and 41.1%, respectively, as compared to the published liquefaction process. The figure of merit was found as 27.0% in the krill-herd-optimized single mixed refrigerant process, whereas it was 22.2% in the base case.