Experimental investigation on oxygen diluted partially premixed and oxygen enriched supplemental combustion for low emission

As one of the main sources of the air pollution, the NOx emission from combustion is difficult to avoid. In this research, a combustion method, named as Oxygen Diluted Partially Premixed and Oxygen Enriched Supplemental Combustion (ODPP/OESC) was proposed to reduce the NOx generation by adjusting the oxygen concentration. The relationships between the operating parameters were deduced. The effects of the ODPP/OESC on the NOx and CO emission were evaluated experimentally. Design of Experiments (DoE) was conducted to obtain the optimal operating parameters through the Response Surface Methodology (RSM). Further statistical analysis indicated that as the dominant operating parameter, the lower oxygen mole fraction of oxygen diluted air (Yod) resulted in lower NOx but higher CO emission. The Yod makes the most contribution to the NOx and CO emission, then the oxygen mole fraction of oxygen enriched air (Yoe) does, and the equivalence ratio of premixed gas (ERp) does the least. The regression analysis yielded two relationships between the NOx(CO), Yod, Yoe, and ERp. The optimal operating parameters were obtained by the RSM and verified experimentally. NOx and CO emission were 22.6 mg/m3 and 362 mg/m3 under the optimal condition, respectively. So the ODPP/OESC was promising and feasible for the low emission of the CH4/air combustion and the RSM can be used to control the combustion emissions.