Biomass and Bioenergy

This paper presents a CFD study of a fast pyrolysis process in a pilot-scale auger reactor. By providing a detailed CFD simulation of this reactor, we are capable to obtain a clearer insight into the complex physical phenomena associated with multi-phase flow dynamics, heat transfer and chemical kinetics. The three main products of the process are solid bio-char, condensable vapours and non-condensable gases. Therefore, a multi-fluid model coupled with a chemical solver is a suitable approach for the simulations. The feedstock is a lignocellulosic biomass which composed of cellulose, hemicellulose and lignin. The biomass decomposition is simplified to ten reaction mechanisms. Three different phases that are taken into account are condensable/non-condensable phase or the gas phase as the primary phase, solid reacting phase or biomass phase as a secondary phase and non-reacting solid phase (steel shots) or heat carrier as the other secondary phase. Each phase composed of different species. The results for the product yield shows a good agreement between the CFD results and the experimental data previously received for the simulated reactor. The outcome of this study provides a validated CFD model for industry and researchers that may apply to optimize the operating conditions of the auger reactors in future.