A laser-based sensor for measurement of off-gas composition and temperature in basic oxygen steelmaking

We are developing an optical sensor for process control in basic oxygen steelmaking. The sensor measures gas temperature and relative CO/CO2 concentration ratios through the furnace off-gas during oxygen blowing. In the current configuration, the laser beam is transmitted through the process off-gas directly above the furnace lip and below the exhaust hood, and is being tested at Bethlehem Steel's Sparrows Point Division, Baltimore, MD. Rapid analysis of the detected laser radiation provides the input for real-time control of steelmaking processes. Dynamic gas composition and temperature information provided by this technique are being evaluated for optimizing variables such as lance height, oxygen flow, post-combustion control, and prediction of final-turndown bath temperature and carbon content. The noninvasive nature of the optical sensor renders it robust, relatively maintenance-free, and useful for characterizing off-gas streams in general. Additional applications of the method are process control for electric furnace and bottom-blown oxygen steel-making processes.