Thermochemical Characterization and Kinetics of Biomass, Municipal Plastic Waste, and Coal Blends and Their Potential for Energy Generation via Gasification

Feedstocks such as coal, biomass, plastics, and their blends have the potential to serve as fuels for the thermochemical conversion process owing to their relatively high calorific values. Nevertheless, the relative proportion of these feedstock blends has a pivotal influence over the overall energy conversion efficiency. Consequently, conducting a comprehensive study to optimize the blend proportion becomes crucial in order to obtain an optimal fuel. The study aims to investigate the thermochemical characterization and kinetics of blends composed of lignite coal, southern pine biomass, and municipal waste plastic blend to optimize the blend proportion. This optimization has been achieved through an analysis of 12 distinct blends, considering factors such as combustion reaction kinetics, combustion stability, and comprehensive combustion indices. The reaction kinetics, including activation energy, pre-exponential factor, and reaction order, were estimated using various methods, including Vyazovkin, Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, Master-plot, and multidistributed activation energy methods. The investigation revealed that increasing the biomass content within the blends enhances both the combustion stability and combustion performance. The multidistributed activation energy model exhibited a good fit with both the experimental thermogravimetric and the derivative thermogravimetric curves, achieving linear regression fitness values of 0.99 and 0.95, respectively. To showcase the viability of these blends as energy generation feedstock, the optimal blend comprised of 60% biomass, 10% coal, and 30% municipal waste plastic blend, possessing the lowest activation energy (110 kJ/mol), was employed as the feedstock for the fluidized bed oxy-steam gasification process. The gasification process resulted in a synthetic gas consisting of 47.79 mol % H-2, 27.96 mol % CO, 5.85 mol % CH4, and 18.38 mol % CO2 (nitrogen-free basis) with a cold gas efficiency of 72.88%. The findings of this study can offer valuable insights into global industries engaged in the thermochemical conversion of solid waste materials.