Swirling stabilisation cuts nitrogen oxide emissions
15 Jan 2000
A combination of two combustion technologies could be the key to reducing NOx emissions from coal-fired furnaces. Fortum, a Finnish engineering firm, claims that its new burner design can reduce NOx production by up to 70 per cent compared woith conventional burners, producing levels as low as 65mg NO2/MJ, while also reducing the amount of unburned carbon in the fly ash.
The system, designed for burners which use pulverised coal from several sources, combines over-fire air and rapid ignition technologies, which both work to stabilise the flame. The air stream supporting combustion is split into three streams: a primary stream, within the flame itself; a secondary, swirling stream, which transfers hot combustion gases from the flame to speed up ignition; and a tertiary zone, separated from the primary zone by a guide sleeve, which forms a reducing flame.
The result of this is a very intense flame with a sub-stoichiometric zone near the burner tip, which reduces NOx production within the flame and the burner.
