Mercury removal by biochar prepared under biomass reburning in a simulated flue gas

摘要

Biochar prepared under biomass reburning in a high-temperature entrained flow reactor was used as mercury sorbent. The effects of biomass species, adsorption temperature, initial mercury concentration and HC1 content on elemental mercury (Hg~0) removal characteristics were investigated in an in-duct sorbent injection apparatus. The results showed that biochars have a certain mercury removal performance, whose efficiency is around 30%. Mercury removal efficiency of RH-biochar is little bit larger than that of WH-char, increasing reburning temperature is helpful for mercury removal. Mercury removal efficiency increases continuously to 34.2% during injecting RH1050 as adsorption temperature increase from 80 °C to 160 °C. but it shows fluctuant pattern and achieves the maximum of 36.75% at adsorption temperature of 100 °C during injecting RH1150. Mercury removal efficiency presents a pattern of increase first and decrease latter during injection of RH1050 and RH1150 as initial mercury concentration increases from 15 μg/m~3 to 40 μg/m~3, and the maximum average mercury removal efficiencies of 35.6% and 37.35% achieve at the initial mercury concentration of 25 μg/m~3. HC1 has an obvious promotion on elemental mercury removal. The average mercury removal efficiency during injecting RH1050 can be achieved more than 90% while HC1 content of N_2+HCl is larger than 50 μL/L.