Analysis of the Gaseous Reduction of Porous Wustite Pellets by Response Surface Methodology

In the present study, numerical simulation, regression modeling, sensitivity analysis, and optimization are implemented to analyze how the reduction rates of wustite pellets are affected by the operational variables. Overall reduction time as a function of temperature, pellet diameter, porosity, gas ratio, tortuosity, gas utility, and pressure was computed by the numerical solution of the time-dependent governing differential equations describing the gas concentrations and temperature variation within a porous pellet of wustite. Bulk temperature, pressure, and pellet size were selected based on the screening analysis, which were then used for the main regression modeling to quantify and evaluate their effects on the overall reduction time. The resulting correlation equation gives the reduction time as a function of the important reaction conditions, within their selected ranges, without having to numerically solve the complex partial differential equations. The pellet diameter and pressure were the two most influential factors, followed by other ones. The sensitivity analysis results showed that the higher the temperature and pressure, the less influential their variations in the reduction time, especially at small pellet diameters. On the other hand, the reduction time displayed the highest sensitivity to the aforementioned variables for large pellets and at low pressures and temperatures.