The current study focuses on the development of a real-time, integrated, and automated production scheduling optimizer for the air separation industry. This optimizer, produces an optimal weekly visual schedule for the nitrogen liquefaction units (NLUs) based on electricity prices and customer demand, thereby facilitating cost savings and reducing manpower requirements. Customer demand, penalties for plant start-ups, inter-site optimization, minimum running and rest time, the permissible number of start-ups per week and per day, as well as turn-on time and storage levels, constrain the model. The performance of the proposed framework was validated through retrospective analysis (RO). Operational data for two NLUs (NLU-1 and NLU-2) from 2024 to 2025 were utilized and scrutinised relative to proposed operating strategies suggested by the optimizer to identify opportunities for reduced operating expenditure. The problem was solved by considering a weekly period and half-hourly electricity prices. Initially, analysis was conducted inde.pendently on two sites, resulting in an overall average net saving of approximately 6.52% in operating costs over the two sites. This increases to roughly 7.11% when inter-site optimization is implemented, which, given the nature of the business, represents a substantial financial benefit. Disaggregated analysis was also conducted, indicating an overall reduction in operating costs of approximately 4.29% and 10.50% for NLU-1 and NLU-2, respectively, without inter-site optimization. In the case of inter-site, the savings for NLU-1 increase to 7.18%, whereas the savings for NLU-2 decrease to 6.99%. However, the business’s overall savings increase by shifting load from NLU-1 to NLU-2 when capacity allows. The developed optimizer has been implemented at Linde BOC UK to drive the weekly schedule.