Technical Market Support » Thermal Coal
Electrostatic precipitation is currently the most common method applied throughout the world for collection of fly ash from power station boilers. Electrostatic Precipitators (ESP) are available in capacity suitable for the largest boilers, are relatively cheap to construct, may achieve very high collection efficiencies and generally have low operating costs.
However, it is well recognised that ESPs are sensitive to coal properties and it is necessary to ensure that coal and plant are properly matched.
ACARP have been advised that the marginal precipitator performance of some Australian Coals is being raised as a concern by certain export customers. In particular it is believed that sodium oxide (Na2O) in ash can play a key role in determining ESP performance and this has been recognised by evaluation criteria used by some utilities. However it is not clear what constitutes a critical level, what the role of other ash constituents may be and what is the relative influence of other factors such as fly ash sizing.
As a consequence ACARP initiated this technical review of the impacts of ash quality on ESP performance focussing particularly on the issues of Na2O in ash, the role of other constituents and the relative influence of factors such as particle sizing.
The literature on ESP performance and related matters is extensive and the present review is not intended to be comprehensive. Rather, the approach taken was to seek to document the phenomena at play in the ESP and to identify papers representative of the state of the art in each of these areas. Based on this information tentative conclusions are drawn regarding knowledge gaps and the need for these areas to be addressed.