Keywords: particulate matter, pollution controls, control costs, hybrid particle collection systems
Advances in control of PM2.5 and PM2.5 precursors generated by the combustion of pulverised coal
Particulate matter smaller than 2.5 mm in aerodynamic diametre (PM2.5) from coal-fired boilers is composed of directly emitted (primary) particles and particles formed from precursors (secondary particles). Technologies to reduce emissions of precursors to secondary PM2.5 emitted by coal-fired utility plants include wet and dry flue gas desulphurisation (FGD). Limestone forced oxidation (LSFO) systems are the predominant wet FGD technology in use, and lime spray dryers (LSDs) represent the predominant dry FGD systems. A predictive model indicates that LSD systems have lower annualised costs than LSFO systems for coals with less than 2% sulphur and for plants smaller than 300 MWe. Control technologies for primary PM2.5 include hybrid systems such as the combined hybrid particulate control system and an electrostatically enhanced fabric filter (ESFF) system. The ESFF can provide improved PM2.5 collection and lower fan power requirements compared to a conventional pulse-jet baghouse.