Thermal behavior and kinetic analysis of co-combustion of wheat straw and polyvinyl chloride under different oxygen concentrations through thermogravimetry

Co-combustion characteristics of wheat straw with polyvinyl chloride under different oxygen concentration atmospheres were investigated using a thermogravimetric analyzer. Experimental samples included wheat straw, polyvinyl chloride, and their blends. The results showed that when the wheat straw was blended with polyvinyl chloride, there was an inhibition for devolatilization in the volatile combustion stage. However, during the char combustion stage, a promotion was observed. As the oxygen concentration increased from 10% to 40%, the ignition temperatures, burnout temperatures, and maximum reaction rate temperatures of all samples decreased, and the combustion characteristic factors (S_N) increased. The combustion of wheat straw was significantly affected by oxygen concentration, whereas the polyvinyl chloride and blends were affected relatively slightly. Especially, as the oxygen concentration increased from 30% to 40%, the combustion of polyvinyl chloride and blends improve slightly. The reason for this behavior is attributed to the diffusion effects of the oxygen and the microstructure changes of the samples. In addition, the activation energies of the co-combustion process under the four atmospheres, for all samples, were calculated by Flynn–Wall–Ozawa method. The kinetic results show that the diffusion effect of the oxygen influenced the apparent activation energies of combustion reaction and the compensation effect of activation energies exists.