A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator — I: Hydrodynamic performance

Abstract

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.

A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator-II thermochemical performance and products

“…To provide a robust tool for the development, optimization and scale up analysis domain can be found in part I of this study [7]. This is described briefly here as a column of 6.9 cm diameter and 133.5 cm height connected at the lower part to a solid receiving tank.…”

“…In the first part of this study, Yu et al [7] theoretically studied a downer reactor equipped with a novel solid gas separation mechanism. The study presented a valid computational fluid dynamic (CFD) model to predict the reactor multiphase flow features and provide the platform for further development to predict biomass pyrolysis behaviour and products.…”

“…In this second part of the study, the CFD hydrodynamic model developed in part I [7] has been extended to include equations describing the heat transfer and thermochemical reactions taking place during fast pyrolysis of biomass. The main objectives of this paper are:…”

Modeling and Performance Analysis of Biomass Fast Pyrolysis in a Solar-Thermal Reactor

“…The solid-gas separation method applied in this study is relatively new and its application in chemical reactors has only been reported in few recent studies by Huard et al 27 and Yu et al [28][29] . In these studies, it was shown that the separation device can achieve more than 99% separation efficiency in downer reactors.…”

“…27,28 Figure 7. Temporal evolution of the solid separation efficiency measured at the tip of the gas exit pipe.…”