DEVELOPMENT OF ONE-DIMENSIONAL MATHEMATIC AL-MODEL FOR PULVERIZED COAL COMBUSTION CONSIDERING PARTICLE DISPERSION

A one-dimensional mathematical model of pulverized coal combustion in a blast furnace considering particle dispersion has been newly develop ed. On the basis of the model, the combustion efficiency was precisely estimated by setting the dispersion parameters properly for the lance structure. Evaluation of the effect of lance structure on the combust ion behavior using this mathematical model suggested that the combusti on efficiency in the raceway was greatly improved by intensifying the dispersion of particles. It was estimated that this phenomenon was res ulted from the increase of the gasification rate of char particles cau sed by heating-up and the pyrolysis of the coal particles followed by the combustion of the volatile matter with peripheral oxygen. Moreover a simulation using an oxy-coal lance was carried. out. The oxygen sup plied from the lance tip was rapidly mixed with the hot blast as coal particles were dispersed, and concentration of oxygen that contributes to coal combustion decreased soon after injection. Therefore, injecti on of pulverized coal with the oxy-coal lance showed little improvemen t in combustibility compared with a normal single lance. In conclusion , taking the particle dispersion into account in the one-dimensional m odel, it became possible to make a quantitative approach to evaluate t he effect of lance structure, lance arrangement and the manners of oxy gen enrichment in an actual blast furnace.