Investigation of ash deposition characteristics on rough membrane wall surface coupled with impact-detachment mechanisms

Ash deposition presents significant operational challenges in radiant syngas cooler (RSC) of entrained-flow coal gasification systems. The combined effects of particle impaction, corrosive interactions, and incomplete deposit removal collectively drive progressive surface roughening of membrane wall, complicating accurate prediction of deposition processes. This study developed a comprehensive modeling framework incorporating ash particle melting characteristics to impact dynamics and established random rough surface structures for detachment analysis. The integrated impact-detachment ash deposition model demonstrates good agreement with industrial operational data. Results reveal that the thickness distribution is correlates with impact rate distribution of ash particles, showing over 80 % deposition rates in the middle-upper zone. The dimension of the deposited ash particles is within the range of 0–300 μm. The drag forces govern particle movement at St < 1, while inertial forces dominate at St > 1. Parametric analysis indicates surface roughness and ash viscosity primarily influence deposit thickness in upper zones, where viscosity effects surpass roughness impacts. The interaction between roughness and viscosity exhibits negligible synergistic effects on deposition. These findings elucidate the impact-detachment mechanisms governing ash deposition on rough surfaces, providing a theoretical basis for effective prediction of ash deposition in industrial RSC for entrained-flow coal gasification.