Effect of fuel heap shape on air flow in a side-fed biomass gasifier based on dem-cfd simulation

In recent years, because of the rapid reduction of other conventional energy and growing earth population, biomass usage has increased considerably. As a promising renewable energy technology, biomass gasification offers the highest efficiency among all biomass conversion routes. The subjects in this paper are updraft, side-fed and fixed bed gasifiers based on the method of air supply and the position of the feeding system. It is assumed in most research that the fuel bed's upper surface is even and smooth. In this case, simulative investigation of gasification with idealized conditions may differ from real applications. Even so, studies with respect to the effect of slope form on air flow within the fuel heap cannot be found in published research. To investigate the effect of the fuel heap shape on local gasification conditions, a small-scale fixed-bed updraft gasifier was modeled. The simulation model consists of a cylindrical container as the gasifier, with a default lateral feeding position and air supply from below. Based on DEM/CFD co-simulations in two open source software, LIGGGHTS® and OpenFOAM®, the air flow was examined. The simulation results were investigated qualitatively and quantitatively in terms of air flow pattern, including the uneven pressure and temperature distribution at/over the slope surface. Besides, the effects of operating parameters of the feeding system have been highlighted with respect to modification of the slope form. The results showed that the combustion efficiency at the side of the feeding system is the lowest due to insufficient air flow. According to these first investigations, real fuel heap shape should be taken into consideration for the simulative study of gasification affected by air flow in the future.