Analysis of the Spectral Properties of Premixed, Diffusion, and Hybrid Natural Gas Flames
The spontaneous emission of light by pure premixed flames due to chemiluminescence phenomenon has been widely investigated in order to develop monitoring and diagnostic systems of the combustion process and ultimately to control it. In most cases attention has been concentrated on the lines corresponding to the emissions by OH*, CH* and C2* radicals, which are usually well identified in laboratory scale flames. The present work extends the study to industrial premixed flames, with diffusion pilot flame, at atmospheric and full pressure. The experiments show that for the selected configuration there is a threshold value of the diffusion flame (about 8% over the total amount of the fuel injected in the combustor) under which the diffusion flame has a very low influence in the emission light. The OH* emission is well correlated to the NOx emission while the correlation with the equivalence ratio depends on the combustion condition.