Influence Of The Length Of The Primary Air Outlet On Combustion Characteristics Of A Swirl Burner

Coal still dominates in the structure of China’s energy. In the process of coalcombustion, a large number of NOx and other pollutants formed，and they bringserious damage to the human environment. To improve the environment pollutionproblem, and meet the new national standard NOx emission standards, thedevelopment of control NOx emissions technology is imperative. The low NOxburner is the economic and effective NOx control technology. In order to furtherreduce NOx emissions, usually combine low NOx burner with air classificationtechnology. Domestic scholars have done a lot of research to he central-fuel-rich(CFR) swirl burner, but the research under the condition of air classification aboutthe affect of the nozzle for the central-fuel-rich (CFR) swirl burner is relatively less.Single phase experiments were carried out, and get the conclusion that primaryair flaring length has a great influence on the burner air dynamic field at the exit,with the increase of the the primary air outlet length, the diameter, length andextension of the recirculation region reduce gradually；in the area of r/d=0-0.5, therelative residual temperature increase as the increase of the flaring length, and themaximum mixing speed decreased significantly as the decrease of the flaring length;on the edge of the jet, the mixing speed and the relative residual temperature wereless affected by the primary air outlet length.The thermal state experiment was test on the0.5MW thermal test bed, bymeasuring the gas and temperature distribution in the furnace, finally come to theconclusion：The primary air flaring length has a significant impact on the fireconditions for the CFR swirl burner, as the primary air flaring length increase,pulverized coal ignition delay, and the NOx concentration increase.