National Energy Sanhe Power Generation Co.,Ltd.
Hebei Province Coal-fired Power Station Pollution Prevention andControl Technology Innovation Center
National Key Laboratory of Coal Combustion and Low Carbon Utilization,Huazhong University of Science and Technology

磁性生物焦已被证明是一种高效脱除单质汞(Hg0)的吸附剂。然而,SO2、NO和HCl是富氧燃烧烟气中的酸性成分,其在磁性生物焦脱除Hg0中的作用尚未确定。研究通过模拟富氧燃烧气氛实验装置,深入探讨了不同反应温度下酸性气体浓度对Hg0吸附、氧化效率的影响,以及磁性生物焦的热再生循环性能。结果表明:120℃下,体积分数为0.4%的SO2可促进磁性生物焦对Hg0的吸附,脱汞率达93.5%,但较高体积分数SO2(>0.4%)则产生抑制作用,且少量Hg0被氧化,部分缓解SO2对Hg0的吸附抑制;同时,NO在富氧燃烧气氛中也表现出类似的规律;气态HCl是一种重要的促进剂,在体积分数为0.02%的HCl存在下脱汞率接近100%,可抵消烟气组分带来的不利影响。然而较高温度下,SO2对磁性生物焦脱汞的作用规律与120℃时相似。350℃,体积分数为1.6%的SO2对Hg0吸附抑制作用更强,吸附效率只有19.5%,低于Hg0氧化效率,主要生成更多的C=O等含氧官能团;NO在较高温度下也表现出较强的抑制作用,随着NO浓度增加脱汞率逐渐降低,最终降至50%左右。可见,高温、高浓度SO2及NO不利于磁性生物焦脱汞。此外,脱汞后失活的磁性生物焦具有优异的热再生稳定性,在450℃下热再生并循环4次后仍有80%左右的脱汞效率。

Magnetic biochar has been proven to be an efficient adsorbent for the removal of elemental mercury (Hg). However,SO2、NO and HCl are acid components of the oxyfuel combustion flue gas,and their roles in magnetic biochar removal of Hg have not beendetermined. By simulating an experimental setup with oxyfuel combustion atmosphere, the effects of acidic gas concentration on theadsorption and oxidation efficiencies of Hg at different reaction temperatures,as well as the thermal regeneration cycling performance ofmagnetic biochar,were thoroughly investigated. The results showed that 0.4% SO2 promoted the adsorption of Hg by magnetic biocharwith 93.5% Hg removal at 120 °C,but higher concentrations of SO2 (>0.4%) produced an inhibitory effect and promoted the oxidation of a small amount of Hg,which partially alleviated the inhibitory effect of SO2 on the adsorption of Hg. Meanwhile,NO shows a similar pattern in oxyfuel combustion atmosphere. Gaseous HCl is an important accelerator,and the mercury removal rate in the presence of0.02% HCl is close to 100%,which counteracts the adverse effects of flue gas components. However,the pattern of action of SO2 on Hg removal from magnetic biochar at high temperatures was similar to that at 120 ℃. At 350 ℃,1.6% SO2 inhibited Hg adsorption evenmore,with an adsorption efficiency of only 19.5%,which was lower than the efficiency of Hg oxidation,and mainly generated more oxygen-containing functional groups such as CO; NO also showed strong inhibition at high temperatures,and the rate of mercuryremoval gradually decreased with increasing NO concentration,with the lowest rate dropping to about 50%. It can be seen that high temperature and high concentration of SO2 and NO are unfavorable for magnetic biochar mercury removal. In addition,the magneticbiochar deactivated by mercury removal has excellent thermal regeneration stability,with about 80% mercury removal efficiency after thermal regeneration at 450 °C and cycling four times.

国家自然科学基金资助项目(42030807)

张军峰,魏书洲,孙道荣,等.富氧燃烧气氛下酸性气体对磁性生物焦脱汞性能影响[J].洁净煤技术,2024,30(10):199−207.

ZHANG Junfeng, WEI Shuzhou, SUN Daorong, et al. Mercury removal performance of magnetic biochar by acid gas during oxyfuel combustion atmosphere[J].Clean Coal Technology,2024,30(10):199−207.