Analytical and experimental research for decreasing nitrogen oxides emissions

Influence of swirl number and fuel equivalence ratio on NO emission in an experimental LPG-fired chamber

“…In fact, the effect of residence time on thermal NO x was already indicated [5]. (ii) Prompt NO x [5,7,11]. At fuel rich conditions, the formation of NO x by the prompt NO x takes place due to unburned hydrocarbons.…”

“…At low swirl numbers, the non-uniform distribution of residence time favors the slow reactions of NO x formation in the high temperature zones. In fact, the effect of residence time on thermal NO x was already indicated [5]. (ii) Prompt NO x [5,7,11].…”

“…In spite of these different procedures, most of them aim to reduce nitrogen oxides formation by modifying either the local air/fuel ratio or the temperature in the combustion region. These technical solutions are mainly based on the wellknown kinetic mechanism of nitrogen oxides formation by thermal fixation of atmospheric nitrogen [5,[8][9][10], which is usually referred in the literature as thermal NO x [2,4,5]. According to it, a statistical positive chemical kinetic effect of temperature [5,11] and oxygen concentration on nitrogen oxides formation is observed [4,12].…”

“…It theoretically modifies both air and fuel entrances to cause the formation of a primary zone at high temperatures, where the lack of oxygen reduces thermal nitrogen oxides formation, and a peripheral region rich in oxygen added by a swirling secondary flow, but with lower temperatures that classically contribute to avoid thermal nitrogen oxides [5,7,10,11,[16][17][18][19].…”

“…Several subsets of combustion modifications, such as novel burner, boiler or furnace design, flue-gas recirculation (FGR), reburning, steam injection (SI), water injection (WI) and staged combustion (SC) have been extensively investigated for NO x reduction [1,2,[4][5][6][7]. In spite of these different procedures, most of them aim to reduce nitrogen oxides formation by modifying either the local air/fuel ratio or the temperature in the combustion region.…”