Mathematical modeling and combustion characteristic evaluation of a flue gas recirculation iron ore sintering process

摘要

Flue gas recirculation sintering (FGRS) technology has been applied for two decades with the aim of reducing pollutant emissions. Compared with the conventional sintering (CS), the changes of input gas conditions may influence the bed combustion process greatly. Mathematical models have been developed to predict sintering behavior quantitatively, but few of the previous work focused on FGRS process. In this study, a multiphase theory-based mathematical model is established. This model considers nine kinds of major physicochemical reactions, in which six modes of gaseous reactions make it more comprehensive and accurate to model FGRS process. Heat transfer within/between different solid and gas phases are modeled in better manners. Geometric changes caused by reactive-factors are modeled in simple terms. Sub-models are available to simulate the effects of the temperature, gas supply, composition and content of recirculated gas on combustion characteristics in the sintering bed. Good agreements between simulated and measured results have been obtained from contrasting to six sinter pot tests based on FGRS technology. Four combustion parameters are selected to evaluate quantitatively the advantages and potential problems of FGRS technology. Results show that the flatter maximum temperature (MaxT) profile for FGRS compared with that for CS implies a stronger tumble strength of the sintered ore. The broader MaxT and combustion zone thickness (CZT) curve indicate a higher degree of melt fraction, together with a lower FFS and productivity. To better investigation, further parameter simulation and process optimization of FGRS technology is necessary.