EAF POST-COMBUSTION CONTROL BY ON-LINE LASER-BASED OFF-GAS MEASUREMENT

摘要

At the steel and rolling mill Marienhiitte Graz the laser-based off-gas analysis system LINDARC~R is installed just behind the gap of the 36 t EAF. High reliability and low response time of the system have been proven. The in-situ measured off-gas compounds in the combustion zone are CO and O_2, as well as the off-gas temperature. To post-combust the evolved CO and H_2 during the melt down period, four PC-lances are installed tangentially at the upper furnace shell (freeboard). A measurement campaign with an additional extractive IR/VIS off-gas analysis system has been performed, to acquire information on the off-gas flow rate and off-gas components including H_2, CO_2 and CH_4, which can not be measured by the laser system, but are important for dynamic control and energy balance calculations. A dynamic closed loop control strategy of the post-combustion injectors based on the laser-based off-gas analysis system was developed and tested successfully. Post-Combustion oxy-gen is injected only if required due to high levels of CO in the off-gas, which increased its energetic efficiency dramatically. The trials were evaluated regarding the total energetic behaviour and the achieved savings by using of energy balance model calculations.