A synergistic study of reaction kinetics and heat transfer with multi-component modelling approach for the pyrolysis of biomass waste

Abstract

The present work correlates the heat transport phenomenon coupled with reaction kinetics occurring in the pyrolysis of the coconut shell biomass. The kinetics was modelled assuming an independent parallel reaction of three prominent constituents of biomass namely hemicellulose, cellulose and lignin. Based on the Arrhenius theory and three first order reactions, the kinetic parameters were determined. The activation energy was obtained as 145.20 kJ mol−1, 124.55 kJ mol−1 and 78.60 kJ mol−1 for hemicellulose, cellulose and lignin respectively at a heating rate 10 K/min. The corresponding pre-exponential factor ranges from 5.30х106 to 9.60х109 min−1. The kinetic parameters followed a linear relationship showing an energy compensation effect with its parameters 0.1020 mol kJ−1 min−1 and 7.7753 min−1. Further, these kinetic values for individual components along with other thermo-physical properties had been used to evaluate the transport properties of each. Subsequently, heat transfer map predicted the controlling mechanism with varying particle size for three constituents. Pyrolysis number showed the heat propagation was highest for hemicelluloses of the order 1010, which was further 100 times slower for cellulose and least for lignin. Also, particle size had a predominant effect on transfer properties with a critical size controlling the change of regime for different components.