Experimental Study Of The Modified Kaolin Sorbents On The Reduction Of Ultrafine Particulate Matters Emissions During Pulverized Coal Combustion

Currently, many of the cities in China appeared heavy haze, the heavy haze has become a serious environmental issue and caused the overwhelming public concerns in China. There are various control methods to reduce the PM emission of coal-fired power plants. To reduce the fine PMs, the sorbent addition during coal combustion is proposed as a supplementary technology.The main work is trying to improve the particulate matter(PM) captured efficiency of kaolin by the modification for the first time. In this study, several kinds of typical modification methods are used, namely, sulfate modification, acid modification, alkali modification and intercalation modification. After the modifications, coal burns with the raw and the modified kaolin sorbents separately in an electrical heated drop-tube furnace, and then the mass size distribution of the fly ash particulate is obtained. Then, the sorbent samples burn with sodium acetate in the drop-tube furnace. And then, the raw and modified kaolin are analyzed by some test methods. The results indicated that compared with the raw material, in addition to the alkali modified kaolin, other modified kaolin can significantly improve the PM0.2(particles with the aerodynamic diameter less than 0.2 ?m) captured efficiency.For the modification by aluminum sulfate, this modification method has weakened most functional groups of kaolin, and enhanced the reaction of kaolin adsorbing alkali metals, which effectively reduce the PM0.2 emissions. Compared to the case with the addition of the raw kaolin, the total mass of PM0.2 decreases by 19.84% with the addition of the ASMK samples. After the modification by acid, some functional groups of kaolin are weakened, as a result, these changes enhance the reaction of kaolin adsorbing alkali metals, separately, thus the PM0.2 is obviously decreased. Compared to the case with the addition of the raw kaolin, the total mass of PM0.2 decreases by 41.44% and 31.11% with the addition of the HAMK and HPMK samples. After the modification by alkali, the Al-OH bond and Al-O-Si bond of kaolin are strengthened, the strengthened functional groups inhibit the sectional capture processes of alkali metals by kaolin, so the the reduction of PM0.2 emissions is inhibited. The modification of intercalating has weakened the Al-OH bond, and enhanced the process of dehydroxylation, which enhanced the reaction of kaolin adsorbing alkali metals, so the reduction of PM0.2 emissions is enhanced.