STRUCTURE OF COAL CHAR .2. PORE COMBINATION

A mechanistic model has been constructed to describe pore combination during char gasification. The engulfment of the smaller pores by the larger ones is responsible for the relative depletion of the small pores and enhanced growth of the large pores. Pore volume distributions demonstrate qualitative agreement with laboratory measurements. Pore combination reduces the internal area by the factor (1 — θ), where θ is the porosity, and the θ dependence of the internal surface area is in approximate agreement with the data. However, the magnitude of the internal area is under predicted by a factor of 1.5 to 2. It is apparent that the influence of the parent coal and the effects of pyrolysis and pore growth during gasification are as significant as the effect of pore combination and must be considered before the time history of the pore distribution may be accurately predicted. It is demonstrated that these effects are responsible for an “order one” perturbation to the 1/rp3law derived in Part I. © 1979 G, Taylor & Francis Group, LLC. All rights reserved.