Study on Behaviors of Mercury Emission During Combustion/Gasification Processes of Coal and Sludges

Mercury emissions from combustion/ gasification processes of solid fuels and wastes have been concerned worldwide. First, thermo-gravimetric(TG) experiments were carried out to understand fundamentals of mercury evolution behaviors under the combustion and gasification conditions, using three types of coal and three types of dried sewage sludge as the samples. Then, one sample was burnt in an electric drop tube furnace to study the evolution behavior of mercury in semi-practical combustion processes. Moreover, chemical equilibrium calculation predicted the tendency of mercury evolution under the same experimental conditions. The results obtained show that sulfur content in the fuels inhibits the evolution behaviors of mercury during sludge combustion. For coal, while, the fixed carbon content and Cl concentration in the coal play an important role for the mercury evolution. Under the gasification condition, however, mercury evolves quickly because the elemental mercury is easily formed in the low temperature.