(96c) Improving Mercury Removal Efficiency of a Plasma Enhanced Electrostatic Precipotator

Chlorine atom oxidizes elemental mercury to mostly soluble species. Addition of chlorine gas into a plasma enhanced electrostatic precipitator, used to clean flue gas from coal combustion, will thus increase the mercury removal efficiency in the precipitator. Determination of the chlorine atom concentration, formed inside the chamber, is a key to evaluate this efficiency. A series of experiments are performed to dissociate the chlorine gas in a corona-discharge field formed inside a 15 cm by 3 cm flow pyrex tube at P=1atm, and the chlorine atoms formed are measured by reacting them with butane. The reaction products are quantified using a FTIR. Determination of the chlorine atom concentration in the plasma region near the charging electrode, as a function of voltage supplied, quantity of chlorine injected and the residence time allowed to the chlorine gas between the electrodes will be the first step in optimizing the amount of chlorine reagent gas needed to be added to a precipitator to obtain enhanced mercury removal efficiency. Residence time in the order of milliseconds is experimented to track the behavior of the chlorine atoms in chlorine plasma. This aims at understanding if the 1 minute residence time of industrial precipitators is enough or too much to optimally charge elemental mercury in flue gas stream to obtain a more than 99.9% mercury removal efficiency target for a plasma enhanced electrostatic precipitator.