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Title	Development of Reducing and Direct Fire Heating Technology
Creator	Suzuki, Yutaka; Kaminaka, Motofumi; Takashima, Hiroyuki
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1991
Spatial Coverage	presented at Honolulu, Hawaii
Abstract	A recent majar problem in continuous heat treatment furnaces for steel sheet is the achievement of high productivity without deterioration of Quality. Therefore, as a heating method, a reducing and direct flame heating technology which leads to non-oxidation and Quick heating is attractive . The conventional technolog with pre-mixed gas burners have some problems, such as the limit of maximum steel sheet temperature, the difficulty of use of hot combustion air and the life of burners. To improve these problems, a new technology has been developed. At the first stage, a high performance burner was developed with a small test furnace which was made up of a heating chamber installed a test burner and a nitrogen gas cooling box for heated steel sheets. The features of the newly developed burner are: - well mixing in a burner nozzle with a swirling airflow. - forming a large single flame with a ring-slit burner nozzle. - stabilizing a flame with swiring flow and a cone type burner tile. At the second stage, various characteristics of the developed burner such as maximum steel sheet temperatures for non-oxidation heating, heat-ing rate and NOx formation were investigated with a continuous annealing furnace model which was made up of a pre-heating chamber by waste gas, a heating chamber installed two burners, a soaking chamber with a radiant tube and a nitrogen cooling chamber. The results are as follows. l) Maximum non-oxidation heating temperature is more than 900°C. 2) Heating rate of 0.8t steel sheet is about 100°C/sec at the condition of 1330°C furnace temperarure. 3) Converted concentration of NOx in the pre-heating chamber is less than 50ppm(11%O2) .
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/s6js9t0r
Setname	uu_afrc
ID	7423
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6js9t0r

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Title	Page 5
Format	application/pdf
OCR Text	Show Therefore type C was employed to examine various characteristics with a continuous annealing furnace model. 2.2.4 Steel surface reduction principle by a reducing flame Reduction by a reducing flame is well-known but the mechanism is not clear. Table 1 shows measured stable components in a reducing flame . The observed compositin gas is oxidizer for steel . Therefore there must be some storong reducing agents such as radicals and ions in the flame . One of the reducing agents seems to be H radicals . Fig . 10 shows a reduction area in a reducing flame by a Bunzen burner. Fig . l1 indicates calculated H radical profile by a premixed flame model. Comparing Fig. 10 and Fig.11 . H radical concentrations are high in the reduction area . Fig . 12 shows the effect of flame temperature on H radical concent-rations calculated by the equilibrium model. H radicals increase with flame temperature and this is in good agreement with the fact that nonoxidation temperature increases with furnace temperature. And so the use of preheated air is considered to be effective for non-oxidation heating . When temperature is the same. H radicals decrease with air ratio as shown in Fig.12. But the flame temperatures of the same fuel increase with air ratio. and so there is a H radical peak at a certain air ratio as following examples. AIR RATIO THORETICAL FLAME TEMP. (k) H RADICAL (ppm) O. 6 1830 50 0.7 1983 410 O. 85 2139 520 1.0 2226 350 This explains the effect of CO concentration on non-oxidation temperat ure. - 5 -
Setname	uu_afrc
ID	7410
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6js9t0r/7410