Numerical Simulation of Mercury Conversion During Pulverized Coal Combustion

Abstract

The emission of elemental mercury poses significant risks to both the ecosystem and human health. Therefore, limiting its emission is critical. Although numerous studies have explored various aspects of elemental mercury, the precipitation and transformation characteristics of elemental mercury in pulverized coal under different operating conditions remain poorly understood. This study introduces a novel approach—specifically, the development of a mercury sub-model by integrating thermodynamics, reaction kinetics, and fluid dynamics. Using Fluent, this study simulates the transformation of elemental mercury during the pulverized coal combustion process in a 328.5 MW tangential combustion boiler under varying operating conditions. The study adopts excess air coefficients of 1.11, 1.16, and 1.21, along with corresponding burnout air ratios of 15%, 20%, and 25%. The study investigates three air distribution methods: inverted tower, uniform tower, and positive tower air distribution. The results indicate that lower excess air coefficients and burnout air ratios result in an increased amount of elemental mercury. Additionally, the study demonstrates that inverted tower air distribution can inhibit the precipitation and transformation of mercury.