Effect of Operating Parameters on Agricultural Biomass Mixture Pyrolysis Process in a Batch Reactor

Abstract

Many phenomena affect devolatilization of biomass particles, including mass and heat transfer, chemical reactions and physical transformation. Mathematical models that are capable to describe pyrolysis phenomena can greatly assist the large-scale development and optimization of pyrolysis processes, but to be implemented into large-scale simulation the models need to be simplified at a certain degree. In the present study, an existing mathematical model is used to describe the pyrolysis of a single particle of biomass. It couples the heat transfer equations with the chemical kinetics equations. The common Euler explicit method is used for solving the heat transfer equation and the two-step pyrolysis kinetics equations. The model equation is solved for a sphere particle with a radius of 0.001 m and temperature ranging from 300 to 923 K. An original numerical model for the pyrolysis of agricultural biomass mixture is proposed and relevant equations solved using original program realized in MATLAB. Simplified particle model was validated with the experimental data in a non-isothermal pyrolysis reactor. The sample was heated in the temperature range of 300–923 K at average heating rates of 21, 30 and 54 K/min. The model results showed reasonable agreement with experiments. The difference (between the experimental and model results) is slightly more prominent with decreasing heating rate (21 and 30 K/min), but model results are in much better agreement with the experimental date for higher heating rate (54 K/min). It is demonstrated that a constitutive equation can be used to express devolatilization rate for higher heating rates.