Operability Analysis of Direct Reduction of Iron Ore by Coal in an Industrial Rotary Kiln

Operability analysis enables process designers to evaluate the control aspects of a given process design early in the design cycle. One of the major obstacles to such an evaluation was lack of a metric that quantitatively measures the inherent operability of a given process design. Operabilty Index (OI) framework developed by Vinson and Georgakis (2000) addressed this important limitation. Subsequent work reported by Georgakis and coworkers developed the framework further for dynamic and nonlinear systems (Georgakis et al., 2003). In this communication, OI methodology is used to study the operability characteristics of direct reduction of iron ore by coal in a rotary kiln using a rigorous process model. Though the objective is not to quantify OI, but to develop deeper understanding of the process, the methodology is adopted here for its systematic approach to exploring the operating spaces. The predictions are based on a rigorous phenomenological model developed by Runkana et al. (2010) and made available in the steady-state simulator called DRIKS™. Guided by the OI methodology, input-output relationship of the process were explored using DRIKS™. Key inputs investigated are coal and primary air flow rates. Their impact on selected outputs, especially % metallization are observed and analysed in an effort to identify optimum or robust operating regions. This methodology can help one to locate better operating conditions as well as unsafe and infeasible operating regions.