CCC/227 ISBN 978-92-9029-547-1

November 2013

copyright © IEA Clean Coal Centre

Abstract

Pollutants, such as nitrogen oxides (nitrogen dioxide (NO2) and nitric oxide (NO)), sulphur dioxide

(SO2), sulphur trioxide (SO3), carbon dioxide (CO2), mercury (Hg) and particulate matter (PM), are

formed when coal is combusted in a power plant boiler. With the concern over the environmental and

health consequences of these pollutants, legislation and regulations have been implemented limiting

the amounts that can be emitted to the atmosphere. Emission control systems on conventional

coal-fired power plants typically employ technologies designed to remove one specific pollutant.

These are then combined, in series, to remove several pollutants in order to meet the emission

regulations. This report discusses multi-pollutant systems which remove two or more of the principal

regulated pollutants (SO2, NOx, mercury, particulate matter and CO2) in a single reactor or a single

system designed for the purpose. The emphasis is on commercial or near commercial processes, and

those that are under active development. Ways to improve the co-benefit removal of oxidised mercury

in conventional limestone wet scrubbers, spray dry scrubbers and circulating dry scrubbers are also

included. Multi-pollutant systems can have lower capital and operating costs than a series of

traditional systems to remove the same number of pollutants. Nevertheless, many of the

multi-pollutant technologies rely on by-product sales to be economically competitive. Their footprint

is often smaller than conventional single pollutant counterparts treating a similar volume of flue gas,

making them easier to install in retrofit applications. Some of the systems use modular designs that

ensures easy scalability for larger boilers.