钙基类吸附剂脱除烟气中气态汞的试验研究

Ca-based sorbents for mercury vapor removal from flue gas

用恒温水浴中汞渗透管的汞蒸气发生装置和其他烟气主要气体成分模拟烟气条件，在小型固定床试验台上开展钙基类物质作为吸附剂脱除单质汞的试验研究。结果表明，无SO2时，两种钙基吸附剂以及飞灰和熟石灰混合物对单质汞的吸附效率不高；当SO2存在时，对单质汞的脱除效率可增加15％-20％，30min时吸附量可增加50％以上，且吸附在较高温度下更有利。其原因在于SO2同钙基吸附剂之间的化学反应，在钙基物质表面产生了活性区域，有利于提高对Hg^0的捕捉效率，化学吸附起到了促进吸附的作用。

The characteristics of mercury adsorption by Ca-based sorbents were experimentally measured in a bench-scale fixed-bed mercury adsorption facility with a mercury permeation tube embedded in an isothermal water bath and simulated flue gas compositions. The adsorption performance of calcium-based sorbents including lime, hydrated lime and a mixture of fly ash and hydrated lime is better in the presence of SO2. The presence of SO2 in the simulated flue gas can enhance the Hg^0 capture efficiency from about 15% to 20%, and the adsorption capacity is increased more than 50% at 30 rain of exposure of sorbents to flue gas. It is found that there is a higher capture effect at higher temperature. It is supposed that heterogeneous reactions of Ca-based sorbents and SO2 can increase Hg^0 capture , the sites for Hg^0 capture are influenced positively by the presence of SO2. The behavior can be correlated with the chemisorption mechanism. The potential of Ca-based sorbents used to control Hg and SO2 emissions cost-effectively is great.