Numerical Simulation Of Spanning Of NO_x In The Process Of Off-stoichiometric Combustion

With the development of natural gas industry, all kinds of domestic appliances have been increasing. At the same time, with the application of natural gas, nitrogen oxides emission from gas appliances do harm to the health. The severe hazard of nitrogen oxides pollution is widely realized worldwide, and the concept of indoor pollution is gradually accepted. With the purpose to solve the problem of indoor nitrogen oxides pollution, conducted to study the low-nitrogen oxides effect of off-stoichiometric combustion technology to domestic appliances.First of all, sources and hazard of nitrogen oxides are introduced, as well as the current research status of low-nitrogen oxides combustion technology home and abroad is introduced. Afterwards, afterwards spanning mechanism and restrain avenue of nitrogen oxides are systematically analyzed, and then analyses the natural gas combustion theory of off-stoichiometric in the abstract.By the numerical simulation of off-stoichiometric combustion theoretical analysis, we can draw optimal premixed air ratio:the premixed air ratio of rich fame was 0.6～0.8, and the premixed air ratio of lean fame was 1.6～1.8. Got the numerical simulation model result using the CFD soft FLUENT, confirm solution procedure as well as boundary condition, with adjusting the premixed air ratio of rich and lean fame, we can know when premixed air ratio increase, the ppm fraction of nitrogen oxides decrease in the process of natural gas off-stoichiometric combustion. Thereinto while the premixed air ratio control at 0.8～1.8, the ppm fraction of nitrogen oxides was 0.2 in the export fume, the maximum temperature of firebox was 1810K, and temperature average was 1260K. But for the tradition atmosphere burner, while total air factor was 1.8, the ppm fraction of nitrogen oxides was 169 in the export fume, the maximum temperature of firebox was 2200K, and temperature average was 1380K. Comparing with tradition atmosphere burning, the ppm fraction of nitrogen oxides of off-stoichiometric combustion depress 70% upwards.Off-stoichiometric combustion could effective reducing the spanning of nitrogen oxides in the process of natural gas combustion, specially when the premixed air ratio rational, this could reducing the spanning of nitrogen oxides effectively.