Modeling Char Surface Area Evolution during Coal Pyrolysis: Evolving
Characteristics with Coal Rank
Abstract
Crosslinked metaplast influences char N2 adsorption
specific surface area (SN2), and the influence
changes with coal rank significantly. When crosslinked metaplast is
adequate, planar polycyclic aromatic structures overlap tightly and
SN2 is small. When crosslinked metaplast content
is small, SN2 in crosslinked metaplast is larger
than that in the coal matrix and takes a considerable proportion of
total char surface area. Two exponents, kmat
order and kcrlmet order, representing order
degrees of planar polycyclic aromatic structure arrangement in coal
matrix and crosslinked metaplast, respectively, were introduced in the
previous model for calculating the change of char surface area during
coal pyrolysis. The previous model was extended to include predicting
SN2 of subbituminous and high-volatile bituminous
coals, and was validated with 5 subbituminous coals, and 2 bituminous
coals. The change of SN2 with coal ranks and the
transition characteristics between coal ranks can be predicted.