THE CONTRASTIVE STUDY ON MERCURY REMOVAL BY WET, SEMIDRY AND CIRCULATING FLUIDIZED BED COMBUSTION FURNACE TECHNOLOGY

摘要

IntroductionMercury is one of the most volatile trace elements in coal combustion. Based on data from the US Geological Survey's Coal Qual database, the mean concentration of mercury in US coal is approximately 0.2 mg/kg[1]. The EPA [2] estimated that during the period 1994-1995 annual emissions of mercury from human activities in the United States were 158 tons. Approximately 87% of these emissions were from combustion sources. Coal-fired utilities in the United States were estimated to emit 52 tons of mercury per year into the air during this period, or about one-third of anthropogenic emissions. Wang [3] pointed out that the average mercury content of Chinese coal is 0.22 mg/kg. From 1978 to 1995 the total emitted mercury emission in China reached 2493.8 tons with an average increasing rate of 4.8 % per year during the process of coal combustion. Mercury pollution from coal-fired power plant has become a hot issue for China's scientific research workers and research. At present, wet flue gas desulphurization technology was the mainly technique to control SOX in flue gas emitted from the coal-fired power plant in China. As mercury pollution endangered environment is understood and emphasized by human being, the research on characteristics of mercury emissions from desulphurization system in coal-fired power plant is of great significance.