Heat Transfer Mechanisms and Furnace Productivity During Coil Annealing: Aluminum vs. Steel

摘要

An integrated model, incorporating heat transfer and phase transformation during industrial coil annealing of aluminum and steel has been developed and used to analyze macro-performance parameters such as furnace productivity. The model predictions have been extensively validated with industrial data. It has been shown that when the coil material is changed from steel to aluminum, the dominant mechanism of radial conduction significantly changes from conduction through entrapped gases to heat transfer through contact points. As a result, the productivity enhancement strategies are different for steel (changing gas from nitrogen to hydrogen) and aluminum (increasing the coiling tension) coil annealing. When the gas is changed from nitrogen to hydrogen, the productivity of the steel coils increases by 36%, whereas the productivity of aluminum coils remains invariant with changes in gases. On the other hand, the productivity of aluminum coils shows greater increase with increase in coil pressure as compared to steel coils.