An Experimental Study of Flame Characteristics of Jet Diffusion Flames in Cylindrical Furnaces (1st Report, The Effect of Inner Diameter of Furnace on NOx Emission Property)

Autor: Yoshiaki Onuma, Junya Inohae, Kenichi Nakano, Susumu Noda
Rok vydání: 2005
Předmět:
Zdroj: TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B. 71:303-309
ISSN: 1884-8346
0387-5016
DOI: 10.1299/kikaib.71.303
Popis: The combination of burner and combustion chamber is one of important factors controlling flame characteristics, which has never been to our knowledge investigated systematically. In the present study, coaxial jet diffusion flames in cylindrical combustion chambers have been studied in terms of inner diameter of the combustion chamber, global equivalence ratio and turbulence in air flow. A fuel nozzle is composed of a stainless steel tube of an inner diameter of 2mm with a coaxial pilot burner of 3.19mm i.d., surrounded by two air coaxial tubes of 12mm i.d. and 30 mm i.d. The inner and outer air tubes are for higher and lower air flows, respectively, and the turbulence in air flow is changed by the velocity difference. The main fuel is propane. Hydrogen is used for the pilot flame, with a volumetric fuel ratio of 0.3. The wall of combustion chamber is made of heat-resistant glass to visualize the flames and the inner diameter is changed in a range between 95 mm and 182 mm to investigate the effect of size of furnace on flame characteristics. It has been found that the increase in the diameter of combustion chamber enhances the exhaust gas self-recirculation, as the result decreases the NOx emission. The increase in turbulence in air flow strengthens the entrainment of the exhaust gas transported by the recirculation vortex to the flame. The increase in the global equivalence ratio from 0.2 to 0.8 in the present study decreases the oxygen concentration of the exhaust gas and leads to the diluted combustion through the exhaust gas self-recirculation. It has been found that a proper combination of these factors can yield the low NOx combustion.
Databáze: OpenAIRE
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