Large eddy simulation of biomass gasification in a bubbling fluidized bed based on the multiphase particle-in-cell method

Numerical simulations of biomass gasification in a bubbling fluidized bed have been performed using a hybrid approach, where filtered gas-phase governing equations are solved in a Eulerian framework, and solid particles are modeled based on the multiphase-particle-in-cell method following Lagrangian stochastic parcel approach. A solver has been developed in OpenFOAM after incorporating both homogeneous and heterogeneous gasification reactions. Filtered governing equations of gas-phase variables are solved within the LES framework, where unresolved subgrid stresses and fluxes are obtained using the subgrid kinetic energy equation closure model. The solver could demonstrate transient flow characteristics of gas-solids flows in a fluidized bed, including formation, coalescence, and the eruption of bubbles at the bed surface. For different operating conditions such as steam/biomass ratio, equivalence ratio, and gasifier temperature, predicted concentrations of product gases at the gasifier outlet yield a good agreement with the experimental measurements.