Application of powdered activated carbon coating to fabrics in a hybrid filter to enhance mercury removal

초록

Elemental mercury (Hg-0) is predominant constituent of flue gas emitted from coal-fired power plants. Adsorption has been considered the best available technology for removal of He from flue gas. However, adsorbent injection increases the amount of ash generated. In the present study, powdered activated carbon (PAC) was coated on polytetrafluoroethylene/glass fiber filters to increase Hg-0 removal while concurrently reducing the amount of ash generated. The optimal PAC coating rate was determined in laboratory experiments to ensure better Hg(0 )removal with low pressure drop. When PAC of particle size less than 45 gm was used, and the areal density was 50 g/m(2), the pressure drop remained under 30 Pa while the Hg-0 removal efficiency increased to 15.8% from 4.3%. The Hg-0 removal efficiency also increased with decrease in filtration velocity. The optimal PAC coating rate was applied on a hybrid filter (HF), which was combined with a bag filter and an electrostatic precipitator in a single chamber. Originally designed to remove fine particulates matter, it was retrofitted to the flue gas control device for simultaneous He removal. By employing the PAC coating, the Hg removal efficiency of the HF increased to 79.79% from 66.35%. Also, a temporary reduction in Hg removal was seen but this was resolved following a cleaning cycle in which the dust layer was removed. (C) 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

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