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MERCURY REMOVAL FROM STACK GAS BY AQUEOUS SCRUBBING
Impact/Purpose:
The specific objective of this study is to demonstrate the simultaneous removal by limestone slurry of mercury (Hg?) and chlorine with chlorine injection to the flue gas. In addition, the overall gas phase mass transfer coefficient for mercury removal by chlorine injection will be measured at field conditions.
Combustion of coal and of municipal solid waste releases mercury (Hg) and mercuric chloride (HgCl2) vapors in the flue gas. The flue gas from these sources contains sulfur dioxide (SO2) and hydrogen chloride (HCI) at much higher concentrations than the mercury compounds. Aqueous scrubbing is now used to remove SO2 and HCI from these flue gases. We propose to introduce gases or solution into a conventional aqueous scrubber to generate chlorine (Cl2) or chlorine dioxide (ClO2) in the feed gas. The gaseous chlorine oxidant should react with elemental Hg in the solution at the gas/liquid interface and greatly enhance the rate of absorption of Hg. As a result the existing scrubber technology will also be able to remove Hg emissions at much lower incremental cost than alternative technologies.
Description:
Fundamental results will be obtained on the reaction kinetics in mass transfer
boundary layers for the following systems:
- Hg(g)/Cl2(g)/SO2(g)/sulfite
Hg(g)/ClO2(g)/SO2(g)/sulfite
Hg(g)/Cl2(g)/ClO2(g)/SO2(g)/chlorate/hypochlorite