Deposition characteristics of particles in backward-facing step flow and a radiant syngas cooler

Abstract

Investigation of the mechanism of particle transport and deposition in backward-facing step (BFS) flow is conducive to enhancing the understanding of the deposition characteristics of fly ash in the radiant syngas cooler (RSC). In this study, the regional characteristics of particle deposition in BFS and RSC are deeply studied by numerical simulation. The results show that the deposition of small particles in the recirculation (RC) zone and most particles in the reattachment and redevelopment (RR) zone is promoted while that of large particles in the RC zone is inhibited by the main flow. The variation curves of dimensionless deposition velocity gradually approach to that in straight channel with the increase in deposition length, but they are little affected by the step height and inlet velocity. The differences in particle deposition rates and size distributions between the two zones in RSC are analyzed. The average deposition rate in the RC zone is 21% lower than that in the RR zone, and the proportion of particles smaller than 45.03 μm in the RC zone is higher than that in the RR zone by 24%. This study can provide a basis for the establishment of ash deposition control strategies.