燃尽风和喷水/蒸汽对重油燃烧NO_x排放和火焰稳定性的影响

Influence of Over Fire Air and Water/Steam on NO_x Emission and Flame Stability in a Heavy Oil Fired Combustion System

重油火焰的低NOx排放非常重要,另外,油气锅炉容积热负荷大,极易发生燃烧振动。文中在9?MW燃烧重油试验台上进行试验,研究了投运燃尽风、喷水和喷蒸汽对重油NOx排放的影响,同时利用光谱仪进行火焰闪烁和火焰稳定性的研究。结果显示,投运燃尽风(over fire air,OFA)可有效降低NOx的排放浓度,不过,在开启OFA条件下,喷水法和喷蒸汽法对尾部NOx浓度影响都很小,喷水使火焰振荡频率升高,开启OFA下喷蒸汽会使火焰振荡频率降低,火焰振荡频率越小,火焰稳定性越差。试验结果证实了火焰频谱特性测试系统的有效性。

The low NOx emission of heavy-oil-fired flame is an important physical parameter associated with the characteristics of a combustion process. The steam boiler using heavy oil fuel or gas fuel is prone to thermoacoustic instability. Experiments were carried out on a 9MW heavy-oil-fired combustion test facility. The impact of over fire air （OFA）, water and steam on the NOx emission was studied. The flame flicker signal was obtained by fiber optic spectrometer. Results show that OFA can effectively reduce the NOx emission. However, water and steam both have little effect on the NOx emission when OFA is applied. The flame oscillation frequency is increased when water is injected, while the flame oscillation frequency is decreased when steam is injected. The flame instability becomes worse with the flame oscillation frequency decreasing. The experimental results provide a reliable basis for laboratory research and industrial application. The results also demonstrate the effectiveness of the system for monitoring the flame spectral characteristics.