Influence of jet characteristics nozzle on penetration behavior to vapor film in secondary cooling zones of continuous casting
MA Fan1, LIU Qing1, ZHANG Jiang-shan1, WANG Chao2, SUN Jian-kun1, LI Ming3
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. School of Advanced Engineers, University of Science and Technology Beijing, Beijing 100083, China; 3. Institute of Technology, Nanjing Iron and Steel Co., Ltd., Nanjing 225267, Jiangsu, China
Abstract：The surface temperature of the slab in the second cooling zone of continuous casting is usually higher than 900 ℃. At this temperature,the spraying droplets will not wet the surface of the slab when they contact the high-temperature slab,but only form a vapor film on it,which prevents the subsequent heat transfer between the droplets and the slab surface. In view of the above problems,a nozzle jet simulation calculation model is established based on the flat water nozzle in the secondary cooling zone of continuous casting in a domestic steel plant. The model is verified by theoretical calculation and laboratory experiments. The flow field distribution in the free jet area of the nozzle is studied by numerical simulation and the evolution law of the jet droplet size is measured by the continuous casting nozzle cooling detection system. Combined with the numerical simulation results and laboratory measurement results,the variation law of the depth of the vapor film on the surface of the billet by the jet droplets impacted by the nozzle under different working conditions is quantitatively analyzed. The results show that the maximum jet velocity of the nozzle is at the nozzle outlet. The jet can maintain a large jet velocity near the nozzle outlet. With the increase of water volume,the distance of the jet to maintain a high jet velocity also increases. The axial velocity of the whole jet accounts for more than 80%. When the amount of water is larger, the particle size of jet droplets becomes smaller. As the distance from the nozzle outlet increases,the droplet size at the center of the jet increases gradually and reaches the maximum value. When the water flow rate is 9 and 12 L/min,respectively,the droplet size is basically the same,indicating that the increase of the cooling water does not affect the droplet size distribution when the water flow rate increases to a certain amount. Under different initial flow rates,the depth of droplet penetration through the steam film on the billet surface increases firstly and then decreases slightly with the increase of spray distance. When the spray distance is between 100-200 mm,the penetration depth of droplet is the largest,which indicates that the spray cooling effect is the best when the nozzle spray height is within this range.
马樊, 刘青, 张江山, 王超, 孙建坤, 李明. 喷嘴射流特征对连铸二冷区蒸汽膜穿透行为的影响[J]. 钢铁, 2022, 57(10): 101-109.
MA Fan, LIU Qing, ZHANG Jiang-shan, WANG Chao, SUN Jian-kun, LI Ming. Influence of jet characteristics nozzle on penetration behavior to vapor film in secondary cooling zones of continuous casting[J]. Iron and Steel, 2022, 57(10): 101-109.
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2022, Vol. 57 
