Characteristics of Gaseous and Liquid Fuel Combustion in Laboratory-scale Furnaces

摘要

The flame appearance, temperature profile, and NOx emission associated with gaseous and liquid fuel furnace combustion are investigated through a series of experiments. Numerical simulations are also conducted, for several cases, in order to complement the experimental data. Three fuels, namely, hydrogen, propane, and Jet-A (C_(12)H_(23)), which is a liquid fuel, are examined. Combustion is carried out in two 840-mm long furnaces with diameters of 95 and 182 mm, respectively. Combustion air is introduced to the furnace through two coaxial air nozzles, which generate air velocity difference ΔUa . The flame appearance, temperature profile, and emission index of NOx (EINOx) of gaseous fuel combustion are found to depend strongly on the furnace diameter, D . The results indicate that gaseous fuel combustion can be characterized according to the furnace volume. In addition, the temperature profiles reveal that larger values of D and ΔUa result in lower temperatures. The EINOx is demonstrated to be well scaled with a parameter DU_(f) ΔUa . Finally, the normalized EINOx is shown to be inversely proportional to DU_(f) ΔUa because of the effects of dilution and flame stretch. However, the vaporization process in liquid fuel combustion appears to weaken the sensitivity of the normalized EINOx of Jet-A combustion on the parameter DU_(f) ΔUa .