Characterization and Kinetics for Co-Pyrolysis of Zhundong Lignite and Pine Sawdust in a Micro Fluidized Bed

Co-pyrolysis behaviors of Zhundong lignite and pine sawdust under isothermal conditions were investigated with a focus on the gas releasing characteristics using a micro fluidized bed reactor. The kinetic parameters were deduced by measuring time-dependent changes in the composition of evolved gases from the pyrolysis reactions, employing the universal integral method. The gas release intensity and conversion rate of pine sawdust were quite different from those of Zhundong lignite because of the difference in chemical structure and element content. The effect of blending ratio on the degree of conversion varied significantly for different gas components; H2, CO, and CH4conversion became quicker with an increasing biomass ratio, while the variation of CO2was not obvious. The generally used mechanistic models for gas–solid reactions were examined as ways to interpret the experimental data, and reaction kinetics was deduced with respect to the formation of an individual gas component. The obtained activation energies for the generation of H2, CO, and CH4were much lower from the pyrolysis of pine sawdust than from that of Zhundong lignite, while that of CO2was slightly higher. The activation energies of the blending samples did not change linearly with the blending ratio, showing the interaction between Zhondong lignite and pine sawdust. Via further comparison of the measured and calculated activation energies, interaction was noted between these two fuels for generating the gas components, while the interaction differed for different gas components and different blending ratios.