Techno-economic analysis of low-cost air separation unit with peak-shaving

Abstract Large-scale air separation units are pivotal in separating air into gases like nitrogen, oxygen, and argon, and one crucial for industries such as metallurgy, coal chemical, and petrochemical. However, the high energy consumption of these units keeps operational costs elevated. Moreover, the increasing peak-to-valley ratio in the power grid poses a threat to their operational stability. To address these challenges, this paper proposes a low-cost air separation unit with peak-shaving (LC-ASU). The LC-ASU compresses, liquefies, and stores ambient air in liquid air tank to provide liquid air for distillation columns during peak and off-peak times. It also stores the heat of compression. During peak periods, the unit utilizes the heat of compression to drive the Organic Rankine Cycle (ORC) for electricity generation. In this paper, thermodynamic and economic models for LC-ASU are developed. By increasing power consumption during valley hours and decreasing power consumption during peak hours, the LC-ASU reduces the operating cost by 22.02% while peak-shaving the grid with a peak-shaving index of 6.204 MW. And LC-ASU demonstrates greater economic efficiency as the electricity price ratio increases. This study contributes to cost reduction in ASU and facilitates wider application adoption.