Numerical investigation of mixing and heat transfer of mixed biomass and silica sand particles in a bubbling fluidized bed combustor

Abstract

Using fluidized bed combustion technology, biomass is being promoted for electricity production. However, a lack of biomass in a particular location or season poses a problem, leading to low thermal efficiency when using a single biomass. Thus, mixed biomass is considered a potential solution. This study uses CFD-DEM simulation to investigate the effects of various biomass types, loadings, and blending ratios on hydrodynamics and heat transfer in a bubbling fluidized bed. Coarse bagasse size provides the most efficient mixing behavior for a single biomass mixture. A blending ratio of 1:3 wood chip to coarse bagasse with 5% biomass loading, using 1 mm silica sand, is the appropriate condition. The primary factor for mixing is the difference in biomass sizes, while different biomass loadings have no significant influence. Smaller sand particles enhance the mixing and heat transfer. These findings provide useful guidelines for efficient biomass conditions in fluidized bed combustors.