Kinetic analysis of regional agro-industrial waste combustion

Abstract

Cuyo Region generates a significant quantity of agro-industrial wastes. To exploit this waste for energy production, a combustor was installed in this region. To improve its design and operation, a kinetic study of six agro-industrial wastes combustion, using thermogravimetric analysis, was made. The results show that this phenomenon occurs in four stages: drying, devolatilization, char combustion and residual combustion. Maximum weight loss occurs during the devolatilization stage, followed by the char combustion. The contraction geometry's model describes the devolatilization, indicating that the degradation rate is controlled by the resulting reaction interface progress toward the solid center. Moreover, the first order reaction model describes the char combustion stages, showing that the reaction rate is proportional to remaining reactant(s) fraction. The highest energy activation values were obtained for sawdust at heating rate equal to 10 K/min and plum pits at heating rate equal to 15 K/min for devolatilization and char combustion, respectively, presenting slower reaction rate and more difficulty of a reaction starting. For both analyzed stages, the activation energy values vary slightly with the heating rate. This variation can be due to the kinetic rate being controlled by the occurrence of physical transformation. It does not depend on mass but it depends on temperature.