Industrial reheating furnaces: A review of energy efficiency assessments, waste heat recovery potentials, heating process characteristics and perspectives for steel industry

In the world's competitive industrial market, the development of existing manufacturing equipment's such as industrial reheating furnaces (IRFs) increases profitability in terms of higher production, higher quality, and better energy efficiency. In this review, recent progress and current status in IRFs technology have been presented. A special focus has been highlighted on the recent applications and developments of zone modeling and computational fluid dynamic (CFD) simulations in IRFs, paying particular attention to the integration of slap heating processes characteristics, flow and radiative heat transfer analyses, control strategy, and optimization of the furnace. Moreover, the energy efficiency assessment in terms of efficiency models, long-term measurements, and combustion performance improvement techniques (namely, the effect of burner design and oxy-fuel enrichment) for energy saving and thermal efficiency improvement in IRFs is analyzed. Additionally, studies that investigated the use of different waste heat recovery (WHR) systems within IRFs, to evaluate the potential recovery efficiencies and suitability of the IRFs are discussed in details. The reviewed results showed that the energy apportionment model is the most widely used and regarded as an efficient prediction tool for determining the slap energy efficiency of each heating zone in the furnace. Moreover, the Oxy-fuel combustion technique achieved significant improvements in fuel consumption of the IRF, as it fulfilled high energy-saving improvements of 16 %–26.2 %, compared to the air/fuel combustion. In WHR scope, the findings demonstrated that the potential of WHR in IRFs for the steel industry is within the range of high-medium temperature, and significantly improved the furnace overall efficiency and reduced the fuel consumption required in the furnace via the use of waste heat preheaters/units, and recuperative and regenerative burners in IRFs. Noteworthy discussions, important challenges, critical conclusions, and future strategies for each aspect are also discussed as well.