New Design and Performance Improvement of Components of Heat Treatment Process in Steel Industry

Abstract

For the steel preheating process, the three new gas torch models were designed to enhance the exit flow uniformity of a gas torch with multiple exit holes for effective heating of a steel plate. The objective of this study is to design and to improve performance of new components of heat treatment process in steel industry. The flow uniformity (γ) of the velocity distribution of the multiple exit holes was investigated with the pressure drop ranging from 100 to 500 Pa. The basic model had flow uniformity ranging from 0.849 to 0.852, but the three new models had γ1 = 0.901 - 0.912, γ2 = 0.902 - 0.911, and γ3 = 0.901 - 0.914, respectively. The maximum percentage difference of the flow uniformity index between the three new models and the basic model was 7.3%. The basic model with non-uniform flow distribution made a temperature difference of the back side of the steel plate from the center to the edge of around 229oC, while the modified model with uniform flow distribution had a smaller temperature difference of 90oC. For the annealing furnace, the three new models were designed to reduce the temperature difference among the steel pipes by modifying the inlet structure of a furnace and arranging pertinently a bundle of the inside steel pipes. The elbow inlet generated the swirl flow horizontally and a downward injection angle ranging from 0 to 45 degrees generated the downward jet flow followed by the upward buoyancy flow. The temperature difference of a bundle of steel pipes for the basic model was 55.4oC. On the other hand, the temperature differences of a bundle of steel pipes for the three modified models with the downward inlet angle of 0 degrees, 30 degrees, and 45 degrees were 15.3oC, 13oC, and 23.6oC, respectively. Therefore, the elbow angle inlet of 30 degrees was selected to be the optimized angle to reduce the temperature difference among the bundle of steel pipes. The more increased Reynolds number at the inlet the more increased the temperature difference among the steel pipes. Effect of the horizontal (Sh/d) and vertical (Sv/d) steel spacing on the temperature difference of steel pipes was also examined. The lowest temperature difference of the bundle of steel pipes was achieved in Sh/d = 3.13 and Sv/d = 1.56. In short, presently modified annealing furnaces had uniform temperature distribution on the bundle of steel pipes than the basic one.