Ash deposition characteristics of flue gas across a tube using the Eulerian multiphase model with dynamic mesh technique

Abstract

The ash deposition problem majorly affects the stability, safety, and economy of industrial production processes. To investigate the transient ash deposition characteristics of the flue gas flowing across a tube, the Eulerian multiphase model combined with a dynamic mesh technique is first used in this work. The deposition and the removal processes are both taken into account. Four deposition mechanisms are considered in the deposition process, including Brownian and eddy diffusion, gravity, thermophoretic, and turbophoretic forces. Based on the experimental verification results, it is found that the Eulerian multiphase model combined with a dynamic mesh technique can more accurately predict the ash deposition behavior. The overall fouling characteristics are analyzed by the changes in net deposition mass and deposition morphology under seven different working conditions. The results showed that the ash deposits are mainly formed in two regions: β = 165° ∼ 195° and β = 305° ∼ 55°. In addition, one peak is observed in the deposition region on the windward side, and three peaks exist in the deposition region on the leeward side. The periodic shedding regularity of vortices, the separation process of the boundary layer, and the flow patterns of each feature point on the tube surface are studied to investigate the influence of the flow field characteristics on the deposition characteristics. In addition, the causes of the ash deposition in various locations are discussed in detail from the perspective of the deposition mechanism. The findings of this study are beneficial for understanding the ash deposition process and provide an improved approach for ash deposition simulation.