复合钙基吸收剂吸附烟气中汞的试验研究

Experimental Study on Mercury Absorbed from Flue Gas with Ca-Based Composite Sorbent

将飞灰和CaO以4∶1(质量比)混合,在室温25℃下消化10 min,在68℃下干燥40 min,制得基础吸收剂,再添加5%的KMnO4(或NaClO2)和15%的水分,制成可吸附燃煤烟气汞的复合钙基吸收剂.研究了KMnO4/NaClO2添加量,吸收剂中水分含量,温度,进口φ(O2)、ρ(Hg0)、ρ(SO2)和ρ(NO)等因素对复合钙基吸收剂吸附烟气汞的影响.结果表明:随着KMnO4、NaClO2添加量从0增至5%,复合钙基吸收剂对烟气汞10 min吸附量从131.75 ng/g分别增至443.00和876.08 ng/g;在KMnO4(或NaClO2)添加量为5%,水分含量为15%,温度为80℃,进口φ(O2)为6%的条件下,模拟烟气进口ρ(Hg0)从18.0μg/m3增至86.4μg/m3时,复合钙基吸收剂对烟气汞的最大吸附量升至1 203.33 ng/g(或2 391.63 ng/g);当进口ρ(SO2)从1 429 mg/m3增至2 286 mg/m3时,KMnO4(或NaClO2)添加剂相对应的烟气汞最大吸附量降至421.50 ng/g(或860.00 ng/g);当进口ρ(NO)从536 mg/m3增至938 mg/m3时,KMnO4(或NaClO2)添加剂相对应的烟气汞最大吸附量降至336.75 ng/g(或776.38 ng/g).

A Ca-based composite sorbent was developed to absorb mercury from coal flue gas. Fly ash and CaO with a mass ratio of 4∶1 were hydrated at 25℃ for 10minutes and were dried at 68℃ for 40minutes to make the basic sorbent. The basic sorbent was further tested with oxidants such as KMnO4, NaClO2and H2O. During this process the resulting composite sorbent had 5% of KMnO4NaClO2and 15% of water respectively. An experimental study was performed to investigate the effects of the dosage of oxidant （KMnO4NaClO2）, water content, temperature, φ（O2）, ρ（Hg0）, ρ（SO2） and ρ（NO） on the mercury capturing capacity of the Ca-based composite sorbent. The experimental results showed that when the addition of KMnO4NaClO2increased from 0to 5%, the mercury absorption for 10minutes by the Ca-based composite sorbent increased from 131.75ngg to 443.00ngg and 876.08ngg, respectively; under the condition of that the addition of KMnO4NaClO2was 5%, water content was 15%, the temperature was 80℃ and φ（O2） was 6%, when the ρ（Hg0） increased from 18.0μgm3to 86.4μgm3, the maximum adsorption of mercury increased to 1203.33ngg with KMnO4as the additive and 2391.63ngg with NaClO2as the additive; when the ρ（SO2） increased from 1429mgm3to 2286mgm3, the maximum adsorption of mercury decreased to 421.50ngg with KMnO4and 860.00ngg with NaClO2; when the ρ（NO） increased from 536mgm3to 938mgm3, the maximum adsorption of mercury decreased to 336.75ngg with KMnO4as the additive and 776.38ngg with NaClO2as the additive.