改性煤基活性炭对燃煤烟气中汞的脱除

本文以无烟煤为前驱体,采用KOH活化法制备了煤基活性炭,并以NH4I为改性剂对活性炭进行改性,用于燃煤烟气中汞的脱除。实验研究了负载的NH4I的质量分数、烟气温度以及烟气成分对改性活性炭脱汞性能的影响。研究结果表明,最佳的NH4I负载质量分数为0.07;在80~180℃的温度范围内,随着温度的升高,活性炭的脱汞效率逐渐降低。烟气中的O2、CO2、NO、HCl等组分对改性后的活性炭的脱汞效率具有一定的促进作用,SO2则有明显的抑制作用;但由于改性活性炭具有较好的抗硫效果,当烟气中含有微量的SO2时,活性炭的平均脱汞效率仍可达到87.95%。采用热再生法对改性活性炭进行再生,结果表明,400℃下再生的活性炭的脱汞率为95.82%,但随着再生次数的增加,活性炭脱汞效率不断降低。

Removal of Elemental Mercury from Flue Gas by Modified Coal-based Activated Carbon

In order to develop high-efficiency mercury removal sorbent,coal based activated carbon was prepared by KOH activation method with anthracite as precursor and modified by NH4I.The effect of NH4I loading amount,sorption temperature and flue gas composition on Hgo removal efficiency were evaluated.The results showed that modified activated carbon had the highest mercury removal efficiency when the mass percent of NH4I was 0.07,and the mercury removal efficiency of adsorbent decreased with the increase of temperature at temperatures of 80~180℃.The existence of O2,CO2,HCl and NO in simulated flue gas promoted the removal of Hg0,while SO2 had an adverse influence on mercury removal.However,the sorbent has a certain anti-sulfur effect.The mercury removal efficiency was still 87.95%while slightly SO2 presented in flue gas.The regeneration performance of the sorbent was investigated by thermal regeneration method.The mercury removal efficiency was 95.82%after regeneration at 400℃and gradually decreased with the increasing regenerative times.