INFLUENCE OF 2-STAGE AIR SUPPLY ON BEHAVI OR OF KEROSENE COMBUSTION AND NOX EMISSION IN POROUS CERAMIC BURNER

A porous ceramic burner has already been proposed for high turn down r atio in kerosene combustion. However, at higher loads, considerable am ounts of NOx are found to be emitted. This present paper proposes a tw o-stage air supply system for reducing NOx emitted from kerosene combu stion on a porous ceramic burner, and other combustion characteristic of this burner are experimentally studied. It has been confirmed from experimental works that by introducing two-stage air supply the fuel l ean limit is lowered to as low as 0.2 equivalence ratio and that the s table combustion area ranges from 2.0 to 11.5 kW. Then the correspondi ng turn down ratio achieves 5.8. Since the ratio of primary air to tot al air greatly influences not only the temperature distribution in the burner but also the soot formation, the CO concentration and the NOx emission at the exit of the burner, this value is regarded as an impor tant operating factor in this burner. By using the optimum ratio of pr imary air to total air, the NOx emission is found to be approximately one-quarter to that of the emission with single-stage air supply.