In Situ Coal Tar Reforming with Char and Its Reaction Model Considering Pore Consumption

The characteristics of in situ coal tar reforming with char were investigated. Subbituminous coal was continuously fed and pyrolyzed at 1173 K in a drop-tube reactor in the presence of additional char. The ratio of the additional char to coal was varied to clarify the effect of the amount of the additional char on tar reforming. The effect of the operation pressure was also evaluated. The experimental results showed that the heavier tar having more than four ring aromatics decreased with the increase in the amount of char. The reforming reaction of the heavy tar with additional char was somewhat restricted with the increase in the operation pressure (<0.9 MPa). The pore structure analysis of the char indicated that the micro-, meso-, and macropores were plugged after the tar-reforming reaction. A reaction model was proposed considering the pore plugging of the additional char to explain the experimental results. The results of the model fitting indicated that the amount of pore available for tar reforming decreased with the increase in the operation pressure. The model also suggested that the kinetic constant and residence time are more effective in increasing the conversion of tar than the amount of the available pore.