It is estimated that over 300 new fabric filters (FF) are going to be needed for the capture of mercury and fine particulate. We have found that cupric chloride-impregnated activated carbon (CuCl2-AC) demonstrated excellent Hg(0) capture performance. Our previous studies show that mercury adsorption is a sequential process of Hg(0) oxidation and oxidized mercury adsorption over CuCl2-AC. Therefore, it is essential to separately determine the chemical reaction and physical adsorption kinetics for the prediction of Hg(0) vapor removal by CuCl2-AC for sorbent injection.
A model for the physical adsorption of mercuric chloride (HgCl2) onto raw activated carbon (AC), 4% and 10% CuCl2-impregnated activated carbon (CuCl2-AC) sorbents in a fabric filter was studied based on the adsorption equilibrium and kinetics. Sorbent loading, particle size, filtration time, and CuCl2 loading onto AC were found to be the major factors determining an HgCl2 removal efficiency. Although high sorbent loading and small sorbent particle size result in high HgCl2 removal efficiencies, inlet HgCl2 concentration and superficial gas velocity were found to have little impact on HgCl2 removal. Our operation case study result shows that sorbent injection for a short duration at a high loading followed by the discontinuation of the injection until a cleaning cycle can significantly save a total sorbent amount with high sorbent utilization while the same amount of HgCl2 is removed. The adsorption of HgCl2 onto raw AC and CuCl2-AC in the filter cake was found to be primarily governed by the adsorption capacity difference in the Langmuir adsorption kinetic expression. The study results demonstrate how fundamental adsorption equilibrium and kinetics can be used to design a sorbent and predict its performance in a fabric filter. A modeling result for the chemical reaction followed by physical adsorption will also be presented in this talk.
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