EFFECT OF FLUE GAS RECIRCULATION ON BURNER PERFORMANCE AND EMISSIONS

Abstract

Flue gas recirculation (FGR) is an effective applicable way to reduce emissions. In the present study, external FGR was employed in non-premixed combustion using kerosene as liquid fuel to investigate its effect on flame stability, appearance and emissions. Flame stability can be attained through a reasonable range of recycling ratios up to 40%. Flame appearance exhibits shorter flame with increasing FGR% due to the increased turbulent mixing. Flame temperature was reduced because of dilution effect and increased specific heat of FGR. The flame luminosity decreased and bluish flame increased by increasing FGR%. As a result of the flame temperature decrease, an obvious reduction of NO emissions can be achieved. The NO can be dropped from about 90 ppm to a single digit number. Emissions of CO and UHC increased at high recycling ratios near to flame blow-off and more increase took place at leaner conditions i.e. lowest flame temperature. INTRODUCTION Flue gases from fossil fuel-fired combustion facilities are major contributors to atmospheric pollution. Nitrogen oxides emissions are produced almost entirely by combustion processes. At common combustion temperatures, the NO x in the product gas is almost completely composed of NO. As this gas leaves the combustion zone, it cools and some NO is oxidized to NO 2. However, the exhaust NO x is still typically over 90 percent NO as it is emitted into the atmosphere. After entering the atmosphere, both NO and NO 2 participate in a series of chemical reactions to form other compounds such as ozone and particulate nitrate [1, 2].