The research on NO generation mechanism in MILD combustion of primary combustion gas of waste incinerator by NO-LIF method

Abstract

NO generation mechanism and NOx formation of the inversed diffusion flame (IDF) and MILD combustion formed in the secondary combustion area of waste incinerator were experimentally investigated in order to clarify the NO generation mechanism in the waste incinerator. NO generation mechanism of secondary combustion near the nozzle exit was characterized by NO planar laser induced fluorescence (PLIF), temperature distribution. Besides, ammonia was used as the additives in fuel for understanding the effects of flame structure on NOx formation. The amount of NOx in the exhaust was sampled and analyzed. In order to eliminate the effect of ammonia decomposition, ammonia was replaced with formamide. Results showed that in the case of MILD combustion without ammonia, the NO-LIF signal intensity was weaker than that in IDF without ammonia because the temperature of MILD combustion was more uniform and lower. Furthermore, the NO-LIF signal intensity in downstream of the flame is stronger than that the upstream flame. On the other hand, MILD combustion with ammonia showed larger region of NO-LIF signal intensity than that of IDF with ammonia because the spatially homogeneous reaction region was formed in the condition of MILD combustion. the NO-LIF signal intensity in downstream of the flame is weaker than that the upstream flame. By comparing NO-LIF and OH-LIF in IDF, we found that NO-LIF signal intensity is stronger on the outside of the flame zone than inside. Additionally, IDF and MILD combustion reverse the tendency of NO-LIF signal intensity in the height direction. By comparing with the NO-LIF signal intensity when formamide and ammonia is added, ammonia is not decomposed because there is almost no effect of NO-LIF signal intensity.

Keywords

• two-staged combustion
• mild combustion
• inverse diffusion flame
• no
• no-plif
• nox measurement
• temperature