Investigation on NO reduction behavior within complex atmosphere during pilot ignition of low calorific gas

Abstract

Low calorific gas (LCG) is largely produced in industries and agricultures, but its utilization is difficult due to the poor combustibility and high NO _x emission. The pilot ignition combustion has the potential to improve LCG’s combustibility and also reduce NO production with combining air stage approach. However, the complex atmosphere created under pilot ignition condition could complicate the NO reduction (by CH₄) behavior and should be clarified. This paper is aimed at gain a deep insight on this issue by exploring the interaction between temperature and atmosphere, the individual role of α and CH₄ concentration (or its ratio to NO), and the influence of CO and CO₂ presence. The results show that with dropping α, the maximum NO reduction ratio increases, but a higher temperature is needed to achieve this value. Under fuel rich condition, NO reduction was accompanied with HCN formation, which must be considered to analyze the effective reduction. The CO₂ generated from pilot flame or originally contained in LCG could inhibit the NO reduction, with this effect being more pronounced at a fuel rich atmosphere. For a CO/CH₄ duel reactive LCGs, CO reduces the NO reduction ratio at lower temperature, but improves at higher temperature.