One important aspect of boiler design to which manufacturers given much attention is control of nitrogen oxides emissions by use of low NOX burners and furnace design strategies. Volatile matter content of coal is very important in influencing NOX production. Without air staging, NOX tends to increase with volatile content but with staging NOX emission decreases with increasing volatile content.
The paper outlines the development of these technologies together with the research that has underpinned their development.
For a low NOX burner rapid coal heating is shown to be important. In tests with a semi-anthracite coal (VM 10%) the new CF-a WR burner reduced unburnt loss by 40 to 50%, compared with IHI's conventional low NOX DF burner, but with only a small increase in the level of NOX . Meanwhile, developments of micronising and the wide range burner design promise equally good results with low volatile coals.