Thermogravimetric characterization of dairy manure as pyrolysis and combustion feedstocks

Abstract

Thermogravimetric analysis was used to examine the thermal behavior of dairy manure as a pyrolysis and combustion feedstock. Nitrogen and air were used as purging gases to analyze the pyrolysis and combustion reactions, respectively, and heating rates of 20°C min−1, 40°C min−1 and 60°C min−1 were applied. An Arrhenius model was used to estimate the kinetic parameters (activation energy, reaction order and pre-exponential factor). Results showed four steps for both the pyrolysis and the combustion reactions, with the second step being the most critical one and during which most thermal decomposition of cellulose, hemicelluloses, starch and protein occurred. Thermochemical reactions were determined mainly by temperature. Heating rate influenced the start and the end of the thermal conversions. The activation energies for the two major reaction zones were 93.63 kJ mol−1 and 84.53 kJ mol−1 for pyrolysis, and 83.03 kJ mol−1 and 55.65 kJ mol−1 for combustion. Knowledge of the thermal behavior of dairy manure provides guidelines for future energy utilization.