Experimental validation of complex mathematical model of screw reactor coupled with particle model describing pyrolysis of lignocellulosic biomass

Abstract

Abstract As in every complex technological process design, pyrolysis reactor design and optimization require a mathematical model of sufficient complexity. Aside from properties of utilized feedstock, reaction temperature and residence time of solid and gaseous phase are the main parameters in pyrolysis reactor design. Screw pyrolysis reactor, also known as auger reactor, is a well-known and studied reactor type suitable for pyrolysis of heterogeneous materials. In this work, a complex mathematical model of a screw pyrolysis reactor coupled with a particle model is proposed. Primary pyrolysis reactions as well as secondary tar cracking reactions were taken into account. In addition, heat and mass transfer inside a solid particle and heat transfer between both phases and the reactor wall were considered. Experimental results obtained at a pyrolyzer temperature of 650, 700 and 750 °C and residence time of solid phase of 7, 9.6 and 15\xa0min were compared with data predicted by the mathematical model. Both, tar and gas yield predicted by the model at 700 and 750 °C showed a good agreement with experimental data at all solid phase residence times. However, the model predicted higher gas production compared to the experimental one at 650 °C. The value of relative deviation of char yield remained under 2% under all pyrolysis conditions. The proposed model can be used for simulation and optimization of industry-scale screw pyrolyzers. However, its validity should be verified on wider operation temperature range.