Reduction Process for Sulfur Chemical Looping Combustion with Fe <sub>2</sub>O <sub>3</sub> Oxygen Carriers

Abstract

Chemical looping combustion (CLC) is a new energy-saving and energy-efficient combustion technology. In this study, the possible products of CLC were analyzed by determining the equilibrium constants of competitive reactions of sulfur and oxygen carriers (OCs) at different temperatures. The effects of reaction temperature, sulfur partial pressure, and sulfur dioxide partial pressure on the distribution of solid products were evaluated by computing the dominant region diagram. The gaseous and solid products produced by the reduction reaction of sulfur and OCs at different temperatures were simulated using Aspen Plus. The feasibility of sulfur chemical chain combustion was verified through experiments. Research findings indicated that almost all sulfur reacted with OCs to produce SO2 and metal oxide. In addition, a low sulfur equilibrium partial pressure was beneficial to the generation of metal oxide, whereas a high sulfur equilibrium partial pressure was beneficial to the generation of metal sulfide. Under the conditions of a S/Fe2O3 molar ratio of 1:6, a carrier gas flow rate of 300 ml/min, a sulfur gasification temperature of 500 ℃, and an OC reduction temperature of 900 ℃, sulfur CLC was the best. This study laid a foundation for the practical application of sulfur chemical chain combustion to produce high concentrations of SO2 gas and demonstrated the great development potential in the CLC acid-making industry.