A Numerical Study on Carburization Enhancement of Direct Reduced Iron in a Hydrogen‐Intensive Shaft Furnace

With the intent to enhance the carburization of direct reduced iron (DRI) in a hydrogen‐intensive shaft furnace, the present study assesses a novel strategy involving the injection of preheated methane gas into transition zone of the unit by using a numerical model. Influences of the new operation on key furnace performance are investigated systematically. The results show that the in‐furnace gas flows are altered by changing the cooling gas outlet pressure and three distinct flow patterns are identified. As the outlet pressure increases, the DRI metallization degree increases first and then decreases while the DRI carbon content exhibits the opposite trend. When increasing the feed rate of preheated methane, the metallization degree also shows an “increase–decrease” variation. It is therefore necessary to reduce the outlet pressure when applying an overly high preheated methane feed rate in practice for obtaining an optimal DRI metallization degree. Moreover, a higher feed rate of preheated methane gas leads to an increase of both DRI carbon content and discharge temperature. With a moderate feed rate of 60 Nm 3 /t‐pellet, a notably high carbon content of 0.02 can be achieved. Meanwhile, the discharge temperature of DRI is still below the threshold representing disastrous DRI reoxidation.