Numerical Study on the Homogeneous Reactions of Mercury in a 600 MW Coal-Fired Utility Boiler

Abstract

The homogeneous oxidation of elemental mercury (Hg0) can promote Hg pollution control in coal-fired power plants, while the mechanisms and quantitative contributions of homogeneous reactions in Hg0 oxidation, especially the reactions between Hg and chlorine (Cl), are still unclear. Here, a numerical study on the homogeneous reactions of Hg was conducted within a 600 MW tangentially fired boiler for the first time. A novel Hg sub-model was established by coupling the thermodynamics, reaction kinetics and fluid dynamics. The results showed that the higher Cl content in coal was beneficial to the oxidation of Hg0. The homogeneous reactions of Hg mainly occurred in the vertical flue pass at low temperature. Hg0 was still the dominant Hg-containing species at the boiler exit, and the concentration of mercury chloride (HgCl2) was the highest among the oxidized mercury. When low-Cl coal was fired, the addition of a small amount of chlorine species into the boiler at the burnout area increased the ratio of HgCl2 by over 16 times without causing serious chlorine corrosion problems.

Review on Mercury Control during Co-Firing Coal and Biomass under O2/CO2 Atmosphere

“…Unlike the conditions in traditional power plants where coal is For BECCS systems, mercury not only poses threats to the ecological environment and human health, but also can lead to metal amalgamation, causing serious safety accidents [4]. Mercury is well known to have harmful effects on human health and the environment [5][6][7]. Globally, the current mercury emission standards for coal-fired power plants are mostly in the range of 5-30 µg/m 3 [8][9][10].…”