BIOMASS PYROLYSIS KINETICS MODELLING

The present work is focused on the development of a computational model for the determination of a kinetic model and its parameters, in order to describe several biomasses pyrolysis process. To describe the mass loss, the independent parallel reaction model (IPR) was adopted and mathematically fitted in order to determine its constants. According to this model, the materials devolatilize through multiple, parallel and first order reactions, which take place independently. Each of the reactions corresponds to the degradation of the biomass components, i.e. cellulose, hemicellulose and lignin. The overall mass loss rate is calculated from the sum of each reaction's mass loss rate. Also, the exponential integral, included in the expression of the conversion of the mass sample of each reaction for every experimental point, was evaluated using Hastings rational approximation. Within the model it was possible to determine the contribution of each component to the overall mass loss, as well as the activation energy (E) and pre-exponential factor (A) of the first law reaction of each of these components. These kinetic constants are necessary for the calculation of the reaction's mass loss rate. The goal of this work was to minimize the sum of squares of errors between calculated and experimental values of the overall mass loss rate. For this purpose, the fitting of the model parameters into the experimental data was performed using a program written in C programming language, while the optimization was performed using the EASY (Evolutionary Algorithm System) platform. TGA analysis results used from six biofuels namely castor, jatropha, olive kernel and sunflower seeds as well as giant reed and switchgrass were used for the kinetic modelling.