燃煤飞灰汞吸附动力学及其模型研究  

Adsorption kinetics and models of coal-fired fly ash for mercury removal

作　　者：顾永正[1] 张永生[1] 张振森[1] 徐鸿[1] 潘伟平[1,2] 

机构地区：[1]华北电力大学能源动力与机械工程学院,北京102206 [2]西肯塔基大学燃烧科学与环境技术研究所,美国肯塔基42101

出　　处：《热力发电》2015年第12期11-18,共8页Thermal Power Generation

基　　金：国家高技术研究发展计划(863计划)(2013AA065404);中央高校基本科研业务费专项资金(13ZD04);高等学校学科创新引智计划(B12034)

摘　　要：为了更好地了解汞在燃煤飞灰表面上复杂的氧化吸附机制,在固定床反应器上进行了汞吸附实验,采用表观吸附动力学模型对不同工况下的动态吸附过程进行了模拟,并将模拟结果与实验结果进行对比。结果表明:随着吸附环境温度的升高,燃煤飞灰对汞的初始吸附速率先降低后升高,这与准二级吸附速率常数呈现的规律相符;入口气体流量的增加可降低外扩散阻力;入口汞质量浓度的增加可提高传质推动力,促进飞灰对汞的吸附;粒内扩散控制作用较小;Bangham动力学模型适用于各种工况下飞灰对汞的吸附,最适合于描述固定床中飞灰对汞的动态吸附过程。To better understanding the complicated oxidation/adsorption mechanism of mercury removal on surface of coal-fired fly ashes,the mercury adsorption tests were carried out on a fixed bed reactor.Moreover,apparent adsorption kinetics models were applied to simulate the dynamic adsorption processes of different operation conditions.The results show that,with an increase in temperature,the initial adsorption rate decreased first and then increased,which agreed well with the regularity shown in the pseudo-second order rate constant.The external diffusion resistance reduced with the increasing inlet flow rate.Furthermore,the effective adsorption time might cause the deviation of fitting parameter for pseudo-first order kinetic model.The inlet mercury concentration was beneficial to promoting the mercury adsorption due to the improvement of mass transfer driving force.Result of intra-particle diffusion model shows that the controlling effect of intra-particle diffusion was small.All results in this study were consistent in that the mercury adsorption rate-determining step was given priority to the adsorption of active sites on the surface,external and intra-particle diffusion should be complementary.

关 键 词：燃煤飞灰 汞 吸附动力学 动态吸附 速控步骤 表面活性点位 外扩散 粒内扩散 

分 类 号：X773[环境科学与工程—环境工程]