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This study presents the first part of a CFD study on the performance of a downer reactor for biomass pyrolysis. The reactor was equipped with a novel gas-solid separation method, developed by the co-authors from the ICFAR (Canada). The separator, which was designed to allow for fast separation of clean pyrolysis gas, consisted of a cone deflector and a gas exit pipe installed inside the downer reactor.A multi-fluid model (Eulerian-Eulerian) with constitutive relations adopted from the kinetic theory of granular flow was used to simulate the multiphase flow. The effects of the various parameters including operation conditions, separator geometry and particle properties on the overall hydrodynamics and separation efficiency were investigated. The model prediction of the separator efficiency was compared with experimental measurements. The results revealed distinct hydrodynamic features around the cone separator, allowing for up to 100% separation efficiency. The developed model provided a platform for the second part of the study, where the biomass pyrolysis is simulated and the product quality as a function of operating Corresponding author.

This study presents the first experimental investigation of date palm (Phoenix dactylifera) waste fast pyrolysis in a bubbling fluidized bed reactor. The physiochemical characteristics of the feedstock (from cultivars grown in the Emirate of Sharjah in the UAE), including three anatomical parts of the plant, namely, leaves, leaf stems and empty fruit bunches, have been first analyzed and compared to other popular type of biomass. These components have been subjected to fast pyrolysis and mass balances have been derived. The fast pyrolysis products (bio-oil, and non-condensable gas) have been analyzed in terms of their chemical composition, thermogravimetric profiles, and energy content. The overall product distribution in mass percentage at the pyrolysis temperature of 525 ºC was found to be 38.8% bio-oil (including 10.4% reaction water), 37.2% biochar and 24.0% non-condensable gas. The overall energy conversion efficiency (ratio of energy content in the product to that in the feedstock) was found to be 87.0%, thus indicative of the good potential of converting the date palm waste to energy while eliminating the negative environmental impact and cost associated with waste disposal.

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