生物质热解焦对模拟烟气中汞吸附特性的实验研究

以桑树枝、核桃壳、麦秆和稻秆4种生物质为原料,利用固定床热解实验台制备不同的生物质热解焦,采用比表面积与孔隙度分析仪测量了生物质热解焦的比表面积及其孔隙结构参数.利用固定床吸附实验装置,研究了生物质种类、热解温度、吸附温度及汞初始浓度等因素对模拟烟气中汞吸附性能的影响.结果表明:(1)在相同的热解和吸附条件下,核桃壳热解焦的吸附效果最好,其次是桑树枝热解焦和麦秆热解焦,稻秆热解焦的吸附效果最差;(2)在热解温度为400℃～800℃范围内,600℃热解温度下所得生物质热解焦的吸附效果最好,400℃热解焦吸附效果最差;(3)在吸附温度为60℃～120℃的实验范围内,随着吸附温度的升高,单位生物质热解焦汞吸附量明显降低;(4)在汞初始浓度13.5～38.1μg/m3范围内,随着汞初始浓度的增加,单位生物质热解焦汞吸附量有所减小.

Experimental Study of Mercury Adsorption Characteristics of Biomass-pyrolysis Chars in the Simulated Flue Gas

Different kinds of biomass-pyrolysis chars were prepared from four kinds of biomass named mulberry twig(MT),nut shell(NS),wheat straw(WS),and rice husk(RH) in a fixed-bed pyrolysis reactor.The specific surface areas and pore structure parameters were measured by a surface area analyzer.The mercury adsorption characteristics of the biomass-pyrolysis chars were carried out in a fixed-bed adsorption reactor.The effects of biomass type,pyrolysis temperature,adsorption temperature and initial mercury concentration on mercury adsorption characteristics were investigated.The results indicated that:(1) At the same conditions of pyrolysis and adsorption reaction,the adsorption characteristics of NS char were the best,MT char and WS chars were in middle,and RS char was the worst.(2) At the pyrolysis temperatures of 400℃～600℃,biomass chars pyrolyzed at 600℃ showed the best adsorption characteristics,and biomass chars pyrolyzed at 400℃ performed the worst adsorption characteristics.(3) The unit mercury adsorption capacity of biomass-pyrolysis chars decreased with increasing the adsorption temperature significantly at the adsorption temperature of 60℃～120℃.(4) The unit adsorption capacity of biomass-pyrolysis chars decreased slightly with increasing initial mercury concentration at the initial mercury concentration of 13.5 μg/m3～38.1 μg/m3.