Comparative analysis of thermal oxidative decomposition and fire characteristics for different straw powders via thermogravimetry and cone calorimetry

Safety performance of straw powders, a primary component of biomass pellet fuel, remains challenging. In this work, three straw powders (soybean, peanut, and rape) were studied. Thermogravimetry and cone calorimetry were employed to investigate thermal oxidative decomposition characteristics and fire behaviors. Thermogravimetry (TG), micro-commercial thermogravimetry (DTG), and differential scanning calorimetry (DSC) curves showed that the thermal decomposition of the three samples proceeded in four stages. TG-DTG-DSC data also revealed that their ignition and burnout temperatures and mass loss rates were all distinct. Combustion indices of the three samples were ordered as RS > SS > PS. Based on the cone calorimetry results, critical heat fluxes for ignition were determined to be 25.31, 29.14, and 18.27 kW/m² for SS, PS, and RS, respectively. Critical fire properties such as ignition time, heat release rate intensity, and CO/CO₂ ratio were influenced by biomass species and external heat fluxes. Compared with the other two samples, RS exhibited better burnout performance but was a greater fire hazard. Nevertheless, according to the hazard assessment, the three straw powder samples all had a high fire risk. Additional care must be taken in handling, storing, transporting, and utilizing straw powder in biomass pellet fuel processing.