Experimental analysis of the effect of flue gas recirculation on NOx emissions in a 0.2-MW liquid-fuelled furnace

The implementation of flue gas recirculation strategies for the reduction of NOx emissions in practical liquid fuelled burners is investigated. A laboratory furnace is used and the analysis is based on detailed spatial-resolved measurements of temperature and gaseous species concentrations. It is observed that, while air staging provides major reductions in NOx emissions, with reductions up to about 30%, the effect of adding hot combustion products to the air flow is mainly due to the increase in temperature which facilitates fuel vaporization, rather than to the expected effect of oxygen dilution. However. the aerodynamics of the near burner, which is determined by the operating conditions of the burner, has a greater effect on the NOx emissions than the vitiation of the combustion air.