Simulation of the Agro-Biomass(Olive Kernel) Fast Pyrolysis in a Wire Mesh Reactor Considering Intra-Particle Radial and Temporal Distribution of Products

Abstract

In the present study, a model for the fast pyrolysis of a spherical biomass particle has been developed. The model admits the generation of data which are not accessible experimentally such as the intra-particle temperature and concentration distribution. Simulations have been carried using data from the reactor as well as from literature and the effects of the heating rate and the particle size have been examined. The kinetic model is coupled with a heat transfer model. The reaction kinetic constants have been chosen in order to match the theory to the data taken from experiments carried out in a laboratory wire mesh reactor, for a temperature range from 573 K to 873 K and a heating rate of 200 K/s. Pyrolysis temperature and product distribution profiles in both spatial and temporal directions throughout the particle are presented. The effects of the particle size and the reactor's heating rate in the final pyrolysis products and temperature are shown and discussed. Simulations were carried out using Matlab and the model has been validated against the experimental results. The heating rate, which is an important operating condition in thermal processes, seems to have a positive effect on the biomass conversion to gaseous and liquid products, an increase of the first resulting to an increase of the second. Particle size was found to have a negative effect on pyrolysis conversion as larger particles tend to give higher char yields. For the particular experimental system analyzed here, it seems that the radial non-uniformity is not very large and acceptable results can also be taken using a lumped particle model. Validation of the model with experimental data showed great accordance, thus the model could be used for the prediction of final pyrolysis yields and temperatures.