Particle dispersion behavior of biomasss in a dual-stage swirl gasifier

The distribution of biomass particles in the gasifier significantly influences the conversion efficiency and soot generation during gasification. Numerous studies have confirmed that a single-stage swirl combustor can significantly improve conversion efficiency and is widely used in the coal industry. However, the turbulent structures and shear layers in dual-swirl reactors are highly complex, and existing research lacks systematic investigation into the interactions of biomass particles and recirculation zones. In this paper, a novel dual swirl gasifier is built to investigate the dispersion behavior of biomass particles that would shed light on new generation high-temperature gasification. Both co-swirl and counter-swirl gasifiers with different swirl angles (40°, 50°, and 60°) are investigated. In addition, the influences of inflow rate and the physical property of biomass particles on the two-phase flow behavior are also systematically studied. The vortex structures and particle dispersion in the flow field are quantitatively analyzed. It is found that the counter-rotating vortex structures disrupt the formation of the central exhaust tube vortex, leading to poorer particle dispersion, and the injection of biomass particles apparently changes the size of the central recirculation zone. Moreover, it is also observed that the interparticle distance conforms to a normal distribution. When the biomass particle size is less than 500 μm, the interparticle distance is very small and particles tend to adhere to the wall of the gasifier. The current work provides valuable insights for optimizing the operating conditions of dual-stage gasification.