Influencing factors of mercury removal by pure powdered activated carbon on a bag filter

In order to improve the Hg⁰ removal efficiency and utilization of powdered activated carbon (PAC) of the traditional mercury removal technology which applies activated carbon injection based on a bag filter, a new mercury removal technology with pure PAC on a bag filter was put forward in the present study. Mercury removal experiments were conducted on a small-scale bag filter test bed with pure PAC as the absorbent. The results indicated that the average mercury removal efficiency (AMRE) within the first 65 min decreased from 99.6% to 43.2% when the adsorption temperature increased from 80°C to 170°C; and increased from 75.5% to 84.6% when the volume fraction of H₂O (g) increased from 0% to 8% at 100°C, but it decreased when the H₂O (g) content further increased to 12%. The AMRE increased with the increase of the pure PAC load and decrease of the filtration velocity of the bag filter. When the adsorption temperature was 80°C, the AMRE with pure PAC and that with a mixture of 5% PAC and 95% fly ash within the first 85 minutes were respectively 99.1% and 59.6%. When the mercury removal efficiency was above 75%, the accumulated mercury adsorption amount with pure PAC and that with a mixture of 5% PAC and 95% fly ash were respectively 196.1 and 21.7 μg Hg/g AC, indicating that mixing with fly ash had a very significant effect, and the mercury removal technology with pure PAC on a bag filter had obvious advantages as to mercury removal efficiency and utilization of PAC.