Modeling fast biomass pyrolysis in a gas–solid vortex reactor

Abstract

Conversion of biomass via fast pyrolysis and other methods is positioned to be an important part of the energy landscape in the future. Pyrolysis of lignocellulosic biomass in a gas/solid vortex reactor (GSVR) is modeled to assess the potential of this centrifugal fluidization reactor technology and to explore its process intensification abilities. The production of pyrolysis gases, tar/liquids, and char/ash are examined for various operational scenarios using a simple reaction network. A brief comparison with traditional fluidization technologies is performed. The applied CFD model has been previously validated for non-reacting flows using experimental data from an in-house cold-flow apparatus. The product distribution from biomass pyrolysis between 450 and 500°C was determined to be 14–17wt.% char, 73–76wt.%tar, and 8.5–9.5wt.% pyrolysis gas, depending on the specific conditions of the process simulation, with all conditions yielding complete biomass conversion. The calculated convective gas/solid heat transfer coefficients in the GSVR were determined to be ∼650W/(m2K), which is significantly larger than in non-rotating fluidization reactors. The GSVR exhibited the ability to intensify the biomass pyrolysis process with respect to both production per reactor volume and selectivity toward the desired products, indicating that further investigations with more detailed kinetics and/or experimental reactors is warranted.