煤热解过程中汞和硫的释放特性

Release Characteristics of Mercury and Sulfur During Coal Pyrolysis

采用热分析和动力学分析方法,选取宁武煤田某洗煤厂原煤及其洗选产物为研究对象,考察了在煤热解过程中汞和硫的释放特性。结果表明:汞和硫释放与煤成分有关,在相同热解条件下煤泥和精煤中汞和硫释放率大于矸石和原煤;汞和硫的释放特性受其赋存形态的影响,煤中汞和硫均以无机物结合态为主,精煤和煤泥中的汞更易在低温阶段释放;汞和硫释放率均随温度升高而提高,汞与其赋存体的结合程度弱于硫,温度为500℃时汞释放率已经超过50%,而800℃下硫释放率仅为20%左右;反应时间对汞和硫释放率的影响不大;在煤热解过程中汞释放的反应活化能低于硫,热分析实验结果与动力学推断相吻合。

By means of thermal analysis and kinetic analysis method, the raw coal and its washing products from a coal washing plant in Ningwu coalfield were selected as the research object, so as to investigate the release characteristics of mercury and sulfur during coal pyrolysis. Results show that the release of mercury and sulfur is related to the composition of coal, and the release ratio of mercury and sulfur in slime and clean coal is higher than that of gangue and raw coal at the same pyrolysis conditions. The release characteristics of mercury and sulfur are affected by their occurrence forms. Mercury and sulfur in coal mainly exist as inorganic bound state, while mercury in clean coal and slime is more likely to release at low temperature. The release ratio of mercury and sulfur increases with the rise of temperature, the bonding degree of mercury with its occurrence form is weaker than that of sulfur. Thus, the removal efficiency of mercury is more than 50% at the temperture of 500 ℃, while the removal efficiency of sulfur is only about 20% at the temperture of 800 ℃. Reaction time has limited effect on release ratio of mercury and sulfur in coal. The reaction activation energy released by mercury during pyrolysis is lower than that of sulfur, indicating that the experimental results of thermal analysis are consistent with the kinetic inference.