The combustion time history of a biobriquette is divided into two stag
es in which volatile matter content mainly evolves and burns prior to
char combustion. The volume model for the former stage and the shrinki
ng-core reaction model for the latter stage are employed to calculate
the combustion rate of the biobriquette. In this study, the influence
of briquette shape, compression pressure and types of coal on the comb
ustion rate are investigated by using the two models and experimental
data. The shapes of spherical and cylindrical biobriquettes hardly inf
luence the combustion behavior of the biobriquette (if they have same
diameter and the length of cylinder is equal to its diameter). Compres
sion pressure has no effect on the rate of the former stage but gave o
bvious effect on the latter stage through the density change of the bi
obriquette when it is under about 245 MPa. The reaction rate constant
and its order vary linearly with the fuel ratio of coal briquette in t
he former stage. The type of coal and compression pressure have a larg
er influence on the rate of the latter stage due to different porosity
in the ash layer. Finally, the combustion rate can be analyzed by the
obtained models and semi-empirical equation.