Reduction of iron oxides by carbon in a circulating fluidized bed reactor

Abstract

A theoretical analysis of the reduction of iron oxides by carbon in a circulating fluidized bed reactor is considered in this study. Iron oxide and coal particles are fast fluidized in the main column by a hot stream of gases (N2–CO–CO2–H2–H2O). The analysis considers kinetic and hydrodynamic factors in the reactor and assumes the reduction reaction by carbon to proceed through gaseous intermediates. Using reported base data, the model has been used to generate the temperature and composition profiles in the charge as well as the gas phase, both in the main as well as return columns. Under these conditions, the change in oxygen content of an isolated iron oxide particle during its passage through the CFB has been computed. The results indicate that a freshly introduced oxide particle needs to circulate in the system five to six times before the reduction level approaches about 60%