Mercury and other trace elements removal characteristics of dc and pulse-energized electrostatic precipitator

Removal of zinc-rich ash and mercury from a gas stream using prototype electrostatic precipitators (ESPs) has been investigated. Dust particles collected from the thermal plasma ash volume reduction system of the Matsuyama, Japan, municipal incineration plant were used to study the performance of an ESP to collect zinc-rich ash. The ash was analyzed by neutron activation analysis using the nuclear reactor at McMaster University, Hamilton, ON, Canada. Collection efficiency as high as 99.9% was obtained in the removal of Zn from the flue gas with dc energization of the ESP. The mercury concentration was measured using a cold vapor atomic absorption spectrometer after sampling (OSHA-140 method) from the flue-gas stream. As a function of concentration, the mercury collection efficiency was higher at a higher concentration of mercury. Higher collection efficiency was obtained under negative dc energization compared to other modes of energization of the ESP; however, power consumption under the pulse application was much smaller compared to dc energization. Index Terms--Coal-fired power plant, electrostatic precipitator, fly ash, flue gas, mercury, particle charging, particulate contamination, pulse power, trace elements, zinc.