ECO Process

Powerspan Corporation has developed an integrated air pollution control technology that achieves major reductions in emissions of NOZ (90%), SO2 (98%), fine particulate matter (95%), and mercury (80-90%) from coal-fired power plants; it has been tested in a 1-MW slipstream [100]. The patented technology, Electro-Catalytic Oxidation (ECO), also reduces emissions of air toxic compounds such as arsenic and lead as well as acid gases such as hydrochloric acid (HCl).

In commercial operation, the ECO process is to be installed downstream of a power plant's existing ESP or baghouse [100]. It treats the flue gas in three steps to achieve multipollutant removal. In the first process step, a barrier discharge reactor oxidizes gaseous pollutants to higher oxides (i.e., nitric oxide to nitrogen dioxide, a portion of the sulfur dioxide to sulfuric acid, and mercury to mercuric oxide). Following the barrier discharge reactor is the ammonia scrubber, which removes unconverted sulfur dioxide and nitrogen dioxide produced in the barrier discharge. A WESP follows the scrubber and it, along with the scrubber, captures acid aerosols produced by the discharge reactor, fine particulate matter, and oxidized mercury. The WESP also captures aerosols generated in the ammonia scrubber. Liquid effluent from the ammonia scrubber contains dissolved sulfate and nitrate salts, along with mercury and captured particulate matter. It is sent to a by-product recovery system, which includes filtration to remove ash and activated carbon adsorption for mercury removal. The treated by-product stream, free of mercury and ash, can be processed to form ammonia sulfate/nitrate fertilizer. Powerspan's capital cost estimate is ~$200/kW, including balance of plant modifications [100]. The levelized operating and maintenance costs are estimated to be $2.0 to $2.5 mills/kWh.

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