A Numerical Study on the Operation of the H₂ Shaft Furnace with Top Gas Recycling

The breakthrough route involving a reduction shaft furnace operated with pure hydrogen gas (here called H₂-SF) and the electric arc furnace is widely accepted as one of the most viable future alternatives for industrial-scale production of primary steel with minor CO₂ emissions. It has been clarified that the largest portion of the total energy for the entire route is consumed by the H₂-SF operation, but this unit has not yet received much attention and should therefore be explored. For this, a mathematical model of a reduction shaft furnace is presented in this paper, where a set of simulations were also performed to shed more light on the operation of the H₂-SF equipped with a top gas recycling system. The results show that a high gas feed rate is required for guaranteeing a smooth H₂-SF operation due to the strong heat demand. An increase in the feed temperature of the gas or in furnace height can reduce the required gas feed. However, an excessive length may conversely result in an increase in the total energy consumption. The model and its results are expected to be helpful for gaining a better understanding of the complex processes in and constraints of the H₂-SF.