Thermodynamic analysis and optimization of an air Brayton cycle for recovering waste heat of blast furnace slag

The efficient utilization of waste heat of blast furnace (BF) slag can reduce energy consumption of iron and steel industry. Based on dry slag granulation (DSG) technology which is a text facility dealing with 1.2 ton molten slag per hour, an air Brayton cycle for recovering waste heat of BF slag is proposed. A finite time thermodynamic (FTT) model of the air Brayton cycle is established and its waste heat recovery performance is analyzed. Moreover, by taking power output as objective, the compressor's pressure ratio and inlet relative pressure drop are optimized. Results show that the maximum power output is 51.46 kW the maximum heat recovery efficiency is 11.98%, and the corresponding thermal efficiency is 20.70% when the compressor pressure ratio is 4.29 and compressor inlet relative pressure drop is 0.023. - Highlights: • An air Brayton cycle for recovering waste heat of BF slag is proposed. • A finite time thermodynamic model of the air Brayton cycle is established. • Its waste heat recovery performance is analyzed. • Compressor's pressure ratio and inlet relative pressure drop are optimized. • Maximum power is obtained.