(736c) Hybrid Lagrangian-Eulerian Simulation of Biomass Gasification in a Bubbling Fluidized Bed Reactor

Biomass is a promising fuel resource through gasification to produce synthesis gas. There are several types of gasifier reactors under study. Fluidized Bed Gasifiers are the one that has the potential to scale up to a production capacity more than 15 tons per day. Modeling and simulation of fluidized bed reactors is essential to scale up and optimize the operating condition. Dense Discrete Phase Model (DDPM) is a new computational fluid dynamic (CFD) approach to simulate the hydrodynamic of industrial scale fluidized bed reactors considering particle size distribution in a reasonable computational time. It is a hybrid Lagrangian-Eulerian approach tracking the particles using the Lagrangian approach while interactions between particles are estimated by kinetic theory of granular flows (KTGF).

In this work, the gas and the bed material are modeled as continuum phases whereas biomass particles are simulated as a discrete phase in Lagrangian domain using Dense Discrete Phase Model. Different drag models were used to accurately estimate the mixing of biomass and bed material. The model predictions were compared with experimental results reported for a pseudo two dimensional fluidized bed. The accuracy of motion of the biomass particles in a bubbling condition was evaluated by comparing mixing index and probability of their presence at different points with experimental results. Moreover, the effect of particle size distribution of biomass particles on gasification was studied. Finally, the results showed that the hybrid model had a good prediction of outlet gas composition.