Physicochemical, kinetic and energetic investigation of coal–biomass mixture pyrolysis

• Physical, chemical, kinetic and energetic properties evaluated for fuels & blends
• Biomass leaching increased the pyrolysis activation energy and heat of pyrolysis.
• Additive physicochemical, kinetic & energetic behavior for fuel blend co-pyrolysis
• Developed mathematical model to quantify energetic properties on volatile basis
• Additive energetic properties for co-pyrolysis when expressed on volatile mass basis

The pyrolyzing behavior of solid fuel mixtures was quantified from the physicochemical, kinetic and energetic perspectives using scanning electron microscope and simultaneous thermogravimetric analyzer. The effects of water leaching on biomass pyrolysis and coal–biomass co-pyrolysis were investigated simultaneously from all three perspectives and the behaviors were cross-examined. The water leaching of the biomass significantly decreased the inorganic content and reduced its char yield. The activation energy for the leached biomass was calculated to be higher than the untreated counterparts, and the heat of pyrolysis of biomass increased on water leaching due to mitigation of secondary reactions. The co-pyrolysis of coal and biomass fuel mixtures exhibited a weighted additive physicochemical, kinetic and energetic behavior for the conditions tested in this study. It was shown that the interactions between leached biomass and coal during co-pyrolysis were minimal by successful simulation of co-pyrolysis kinetics using the individual kinetic parameters of coal and biomass pyrolysis reactions. The energetic properties of the fuel samples, viz. heat of pyrolysis and heat of gasification, were calculated on per unit volatile mass basis using a pyrolysis mathematical model. It was demonstrated that these energetic properties were additive in nature for coal and leached biomass co-pyrolysis.