On the Influence of Flue-Gas Recirculation on Pollutant Emissions from a Small-Scale Laboratory Furnace

Mário Costa; Marcos Alexandre Crespo Meireles; Maria da Graça Martins da Silva Carvalho

Key information

Authors:

Mário Costa (Mário Manuel Gonçalves da Costa); Marcos Alexandre Crespo Meireles (Marcos Alexandre Crespo Meireles Ruão); Maria da Graça Martins da Silva Carvalho (Maria da Graça Martins da Silva Carvalho)

Published in

1996

Abstract

This paper describes an experimental study undertaken to investigate the effect of flue-gas recirculation (FGR) on pollutant emissions. The trials have been performed in a small-scale laboratory furnace fired by an industry-type gas swirl burner. Two fuels were used: propane and ethylene. Baseline flames of the two fuels without FGR have been established at three excess air levels and then various degrees of FGR were applied to each of them. To this end, dry flue-gases were injected directly into the secondary air stream before the burner. The data reported includes simultaneous flue-gas concentrations of O2, CO, CO2, unburnt hydrocarbons (UHC) and NOx and of the Bacharach Index for several furnace operating conditions. Overall, the results show, for both fuels, a decrease in NOx emissions with FGR without negative effects on CO, UHC and soot emissions, combustion efficiency and flame stability. For both fuels, it is concluded that there is an optimum value of FGR rate for simultaneously reducing NOx, CO, UHC and soot emissions.