Modelling of ash deposition formation on the surface of superheaters during combustion of Zhundong coal

This study aims to predict the ash deposition rate on the windward and leeward sides of a tube in a two-dimensional computational domain of single row tube array. Based on particle viscosity criterion, an ash deposition model with considering the salt vapour condensation was developed and extended into computational fluid dynamics (CFD) calculation by user-defined function. The transport behaviour of ash particles was numerically described with the Lagrangian method under the effects of inertial force, turbulent eddy, Saffman's lift force, thermophoretic force and Brownian force. The results show that fine particles easily enter into the leeward part of tubes due to the combination effect of turbulent vortex and thermophoresis force. The ash deposition rate and the salt vapour condensation rate on the windward side of the first tube are equally important in the initial stage of ash deposition. While for other tubes downstream, the contribution of vapour condensation to the initially deposited mass is much greater than that of ash deposition. Ash deposition mass on the stagnation position of tubes is mainly from larger particles with the diameter over 10 μm and salt vapour condensation. [Received: September 18, 2021; Accepted: February 14, 2023]