Boosted Over Fire Air
A BOFA (Boosted Over Fire Air) plant is currently being installed at Ratcliffe Power Station in order to reduce emissions of Nitrogen Oxides (NOx) into the atmosphere. NOx is released as a result of the combustion process and the BOFA plant will reduce the level of NOx released into the atmosphere due to the coal burning at a lower temperature. This technology is being introduced because the LPCD (Large Plant Combustion Directive) and environmental policy require sites such as Ratcliffe to reduce emissions to less than 500 milligrams of NOx per cubic metre by 2008 to reduce their impact on the environment.
BOFA works by forcing air into a higher section of the boiler. This causes coal to burn at a lower temperature and as a result reduces the amount of NOx which is produced.The over fire air which is injected into the boiler above the main burner mixes with the tails of the flames and this increases the area available for nitrogen oxide levels to be reduced. The boosted air is transported from the secondary air duct to the air duct at the top of the boiler by two fans found at the basement of the boiler.
