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Title	Thermal and NOx Characteristics of High Performance Oxy Fuel Flames
Creator	Fujisaki, Wataru ; Nakamura, Tsuneaki
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1996
Spatial Coverage	presented at Baltimore, Maryland
Abstract	This paper describes an investigation on the characteristics of oxy-natural gas flames. Experimental investigations were conducted to gain a detailed understanding of oxy-fuel combustion and to develop high performance oxy-fuel flames. The investigation used a semi-industrial scale test furnace with a thermal input of 265 kW and tested various types of flames while monitoring the characteristics of thermal radiation and NOx emission from the flames. A generic burner with an annular oxygen injector and a single-hole gas nozzle in the center was used. A wide range of velocities of gas as well as oxygen was tested to generate various flame characteristics. Gas and oxygen velocity demonstrated a great influence on the radiative heat flux and NOx emission from flames. A lower velocity of oxygen and gas gave a higher total radiative flux with a relatively higher luminous flame and higher NOx emission which was mainly due to air leakage into the furnace. A novel combustion technique was then used based on the results gained from the generic burners. The FDI (fuel direct injection) technique was used, which was already utilized for ultra low NOx emission from high temperature preheated-air combustion. Along with the experimental approach, numerical analysis was made to gain understanding of the flame characteristics. CFD calculation showed an the effect of entrainment of the combustion products into the main stream of the flame on the thermal radiation and NOx characteristics of flames. The results are expected to help the design of optimum high performance oxy-natural gas flames for high temperature processes such as glass melting furnaces.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6f47rq3
Setname	uu_afrc
ID	10608
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6f47rq3

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Title	Page 7
Format	application/pdf
OCR Text	Show Figure 11 shows the recirculation ratio along the furnace axis calculated from the results of CFD calculation. The local recirculation ratio denotes the net mass flow rate of recirculating flow at a certain axial cross section divided by the total mass flow rate (gas and oxygen) discharged through the burner. The net mass flow rate of recirculating flow is defined as the summation of the axial positive mass flow rate at a certain cross section minus the mass flow rate of oxygen and gas at the burner. A recirculation ratio of 0% indicates no recirculation of combustion products into the flame. The recirculation ratio is used to quantify the effect of so-called selfinduced exhaust gas recirculation. Flame A shows the maximum recirculation ratio of about 3900% while flame E shows only 900%. This large difference in the recirculation ratio is thought to greatly affect the flame temperature. Assuming that the combustion products at 1673K, in the range of the flue gas temperature, are recirculated into the flame with the maximum recirculation ratio calculated above, then the estimated adiabatic flame temperature is 1800K and 2200K for flames A and E respectively. Though this estimated temperature may not exactly be the real flame temperature, the recirculation of combustion products appears to greatly affect the flame temperature. A higher velocity of gas and oxygen promotes the recirculation of combustion products, thereby reducing peak flame temperature, total radiative heat flux and NOx emission. Lower velocity of gas and oxygen degrades the recirculation of combustion products, thereby generating higher flame temperature, total radiative flux and NOx emission. Selfinduced exhaust gas recirculation appears to playa more important role on the combustion characteristics of oxy-fuel flames than air-fuel combustion. APPLICATION OF FDI TECHNIQUE TO OXY-FUEL COMBUSTION The FDI (Fuel Direct Injection) technique, which is already utilized for low NOx emission from high temperature preheated air combustion, was tested.
Setname	uu_afrc
ID	10595
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6f47rq3/10595