Analysis of the spontaneous combustion and self-heating of almond shells

Abstract

Self-heating/spontaneous combustion of almond shells in a laboratory oven with control of temperature and weight variation was studied. Two processes were considered: water vapor sorption and chemical oxidation. Different runs were made to analyze the vapor sorption at different oven temperatures, measuring weight gain due to sorption and the variation in internal temperature. With respect to oxidation kinetics, three studies were carried out: the rate of weight variation with temperature, the variation of temperature in a runaway test carried out with a spherical sample wrapped in perforated aluminum foil, and a series of runs to analyze temperatures within spherical samples.A simulation program was developed for the analysis of the sorption run and the kinetic run. In addition, the simulation program was used for the expected runaway condition for a 3–4 m diameter body, discussing the influence of the presence of water vapor.