CO and CO2 reduction and increased energy recovery at a basic oxygen steel plant

The three 320-t converters of BOS No. 2 of Corus IJmuiden are all equipped with suppressed combustion systems for gas recovery. During the blow the air ingress flow through the gap between converter and a movable skirt must be as low as possible. However egress of gas through this gap has to be avoided for environmental reasons. Minimising the air ingress flow has been restricted for two reasons. Firstly, the gas flow from the converter is unpredictable after additions of some materials and secondly, specific conditions in the exhaust system itself may cause egress of gas. This made it necessary to use a high safety margin in the control system. The gas egress flow caused by both phenomena was investigated theoretically and practically. Computational Fluid Dynamic model simulations were used to study the gas flow from converter to quencher. Insights obtained from these simulations were helpful for the interpretation of BOF experiments. This investigation has resulted in an optimised control system that delivers an increase of energy recovery of at least 4 % (cost reduction of 26 Euro/heat) and a reduction of CO and CO2 emissions of 5 and 2.5 %, respectively.