Enhancing energy recovery in the steel industry: Matching continuous charge with off-gas variability smoothing

•A system based on phase change material is inserted into the off-gas-line of a continuous charge electric arc furnace.•The off-gas temperature profile after scrap preheating is smoothed.•A heat transfer fluid through phase change material containers allows to control overheating issues.•The smoothed off-gas profiles enable efficient downstream power generation.•The recovery system investment cost is decreased due to lower sizes of components.

In order to allow an efficient energy recovery from off-gas in the steel industry, the high variability of heat flow should be managed. A temperature smoothing device based on phase change materials at high temperatures is inserted into the off-gas line of a continuous charge electric arc furnace process with scrap preheating. To address overheating issues, a heat transfer fluid flowing through containers is introduced and selected by developing an analytical model. The performance of the smoothing system is analyzed by thermo-fluid dynamic simulations. The reduced maximum temperature of off-gas allows to reduce the size and investment cost of the downstream energy recovery system, while the increased minimum temperature enhances the steam turbine load factor, thus increasing its utilization. Benefits on environmental issues due to dioxins generation are also gained.