Combustion Characteristics Of High Temperature Oxygen-Enriched For Gas Fuel

Combustion process based on oxygen-enriched and high-temperature is an effective method to utilize energy efficiently. The combustion characteristics of natural gas and coke oven gas are analysed by experiments and numerical simulations. The influnces of oxygen concentration, excess oxygen coefficient and rotational or irrotational flow on emission, heat transfer and fuel consumption are discussed. Comparisons between atmospheric and oxygen-enriched condition and between heat storage condition and not are also conducted.The experimental study of oxygen-enriched gas combustion characteristics in high temperature condition is conducted. The results display that, with oxygen concentration increasing, the flame color turned brighter and combusting location moved closer to the fuel outlet. When furnace center temperature deceleration rate increased, the amount of NO_x increased slightly, smoke enthalpy would decrease and the average radiation heat transfer coefficient of deceleration increased, of which the inflection appears at the point of24%oxygen concentration. In addition, flame fold increase with the increase in excess oxygen coefficient, in the meantime the color would be brighter. When excess oxygen coefficient is increased from1.0to1.1, furnace center temperature and NO_x formation rate are increased. Meanwhile the rate of smoke enthalpy and average heat transfer coefficient are further decreased with the excess oxygen coefficient incresaing. However, when excess oxygen coefficient is increased from1.1to1.2, the range of temperature, NOx formation rate and so on variation will be smaller. With heat storage introduced into combustion process, the flame length, center temperature and average heat transfer coefficient will be increasedNumerical simulations of high-temperature oxygen-enriched combustion of coke oven gas in the glass melting furnace are conducted. The results show that: with the increase of oxygen concentration, the overall average temperature of the furnace and the amount of NOX would rise up. On the other hand, distribution uniformity of temperature and NO_x dropped. A gradual increase of the average radiation heat transfer coefficient in flue gas for the glass surface and the furnace wall appears, of which the heat transfer coefficient of flue for the radiation of furnace wall is greater than that in the glass surface. When the oxygen concentration reaches25%, if we continue to increase the oxygen concentration, the average radiation heat transfer coefficient would speed up slowly. If excess oxygen coefficient increased from1.1to1.2, the average temperature of the furnace and NO_x forming mole fraction would also be highly promoted. However, when it is increased1.2to1.3, the change will be smaller. What’s more, the average radiation heat transfer coefficient of glass surface and furnace wall enhanced simultaneously.Under irrotational combustion situation, with the fuel saving ability increasing, the overall average temperature in the furnace and NO_x formation declined and uniformity of the distribution decreased. On the contrary, the average radiation heat transfer coefficient decreases gradually. When oxygen concentration was of25%, excess oxygen coefficient of1.1and fuel savings of10%, the combustion condition is similar to the actual operating conditions. When swirl combustion introduced, fuel savings rate was almost20%, under the condition that the process was similar to the standard one.Simulation results and the furnace operating data collected are in good agreement. The results of this study can provide basic data on further study about the characteristics of high-temperature and oxygen-enriched combustion, and also can offer guidance for transformation and operation of glass melting furnace.