Pyrolysis
conditions and the presence of ash-forming elements significantly
influence char properties and its oxidation or gasification reactivity.
In this study, intrinsic gasification rates of char from high heating
rate pyrolysis were analyzed with isothermal thermogravimetry. The
char particles were prepared from two biomasses at three size ranges
and at two temperatures. Reactivity dependence on original particle
size was found only for small wood particles that had higher intrinsic
char gasification rates. Pyrolysis temperature had no significant
effect on char reactivity within the range tested. Observations of
ash formation highlighted that reactivity was influenced by the presence
of ash-forming elements, not only at the active char sites but also
through prohibition of contact between char and gasification agent
by ash layer formation with properties highly depending on ash composition