Modeling of hydrogen sulfide formation in pulverized coal combustion and its application to a full-scale opposed-firing boiler

In pulverized coal-fired power plants, sulfur-induced corrosion of water wall tubes remains a significant operational issue. Accurate prediction of hydrogen sulfide (H 2 S) concentration distributions within the furnace is essential for evaluating corrosion risks and planning maintenance strategies. However, detailed reaction mechanisms for H 2 S prediction are computationally expensive, and simplified models have not been sufficiently validated for large-scale boilers, leaving a practical research gap. In this study, a simplified global reaction model was developed based on detailed chemical reaction analysis. We introduce a reduced model that preserves predictive accuracy while improving computational efficiency for furnace-scale simulations. The model's validity was evaluated by comparing simulation results with experimental data at two vastly different scales, differing by three orders of magnitude, under two-stage combustion conditions: a 760 kW (thermal input) single-burner test facility and a full-scale 2500 MW (thermal input) opposed-firing boiler. The results demonstrated good agreement with experimental data, including trends in H 2 S peak concentrations due to variations in coal properties such as fuel ratio and sulfur content. Subsequently, the influence of coal properties on the wall-side distribution of H 2 S concentration in the boiler was also investigated. The analysis revealed that while the effect of fuel ratio on H 2 S distribution was limited, sulfur content had a strong positive linear correlation with wall-peak H 2 S concentrations across all cases. These findings indicate the practical applicability of the simplified model for corrosion risk assessment and support its potential use as a tool for coal selection and furnace operation optimization in utility boilers. • Elementary reaction analysis enabled development of a three-equation global model. • The global model accurately predicts H 2 S distribution for various coal types. • Model application to full-scale boilers validated H 2 S predictions on furnace walls. • Thermal-fluid analysis clarified how H 2 S forms and spreads on furnace walls.