Insights into the co-combustion characteristics and synergistic effects of biomass and polyethylene plastic under rapid heating conditions

The combustion process of solid waste has been widely investigated using a slow heating thermogravimetric analyzer (TGA), which is not compatible with actual condition of rapid combustion. The combustion/cocombustion characteristics and synergistic effects of biomass and polyethylene plastic (PE) at a heating rate of 10-1000 K/min were explored in a rapid heating TGA. The kinetic parameters and reaction mechanism were assessed using three methods. Results indicated that the promoting effect of heating rate on the individual combustion reaction increased first and then decreased with increasing heating rate. This was attributed to the fact that the increase of heating rate accelerated the mass and heat transfer rate and improved the combustion efficiency, while the shorter reaction time, the less difference of sample components, and the smaller reaction interval were not conducive to complete combustion. Fortunately, the addition of PE caused the increase of the reaction interval of mixtures and improved the combustion efficiency. The promoting effect of the co-combustion reaction of mixtures increased gradually with increasing heating rate. However, the synergistic effect was most significant when the addition ratio of PE was 25 % due to the melting of PE. Here, Coats-Redfern method provided a more accurate description of the combustion process.