煤温和热解过程中汞释放形态及分布规律研究

The Study of Releasing and Distribution Characteristics of Different Forms of Mercury During Mild Coal Thermal Upgrading

本文选取两种贵州高汞煤,在200～800℃的温度范围内,采用程序升温反应系统加热,利用美国EPA推荐的Ontario-Hydro方法捕捉不同形态汞。研究了在N_2气氛和微氧化性气氛下温和热解过程中汞的释放和形态分布规律。实验结果表明:温度是影响煤温和热解过程中汞释放的主要因素,煤中汞释放率随着温度的升高而明显升高,当热解温度为600℃时,汞释放率可达90%左右。在微氧化性气氛下,汞的释放率随着氧气体积分数的升高而增大。元素汞(Hg^0)是气态汞释放的主要形态,热解停留时间及热解气氛对气态汞的释放形态也存在影响较大。

Two coals from Guizhou province with high mercury content were selected to investigate the mercury releasing and distribution characteristics during mild thermal upgrading under nitrogen and weak oxidizing atmospheres. The experiments were performed by using temperature controlled heating system under temperature range from 200 to 800℃, different forms of mercury were captured by using Ontario-Hydro Method. The results indicated that temperature was the main issue affecting mercury releasing characteristics during thermal upgrading, the releasing ratio of mercury increased obviously with the increasing of temperature, the highest mercury removal ratio could reach to 90% when the temperature was 600℃. Mercury removal ratio also increased with the increasing of oxygen content in the carrier gas. The results also indicated that Hg^0 was the major from of mercury released after mild coal thermal upgrading, but could be affected by the residence time and atmospheres as well.