纯氧助燃预热铁包中废钢过程气流特性的数值模拟

低热值煤气铁包内燃烧预热废钢是提高转炉废钢入炉量的有效措施之一。基于标准k-ε湍流模型耦合涡-耗散燃烧模型,针对铁包内转炉煤气纯氧燃烧过程进行数值模拟研究,探讨气流分布特性及其对烘烤效果影响。结果表明,纯氧燃烧时高温气流速度大,从料堆中心进入、边缘排出,换热距离大,可有效提高低热值煤气燃烧的热利用效率;燃烧过程中铁包盖-体间隙存在空气卷吸、烟气外溢现象。通过调整煤气流量或出口负压,可减少高温烟气外溢、调节烟气回收温度,实现废钢烘烤的最佳气流分布和效果。本预热装置出口负压为-50 Pa、煤气流量约为3 500 m3/h时综合效果较佳。

Numerical simulation of flow characteristics during scrap preheating in hot metal ladle by oxy-fuel combustion

Preheating scrap in hot metal ladle by burning low calorific value gas is one of the effective measures to increase the amount of scrap entering the converter. Based on the standard k-ε turbulence model coupled with vortex-dissipative combustion model, numerical simulation research on oxy-fuel combustion process in hot metal ladle was conducted, and the gas flow distribution characteristics and its influence on baking effect was discussed. The result showed that under the condition of pure oxygen combustion, the velocity of high-temperature flue gas increased and entered from the center of the material pile and discharges from the edge, making a large heat exchange distance, which could greatly improve the heat utilization efficiency of low calorific value gas combustion. During the combustion process, air entrainment and flue gas overflow occurred in the gap between the ladle and its cover. By adjusting the BOF gas flow rate or outlet negative pressure, the overflow of flue gas could be reduced, the flue gas recovery temperature could be adjusted, and the optimal gas flow distribution and the effect of scrap baking could be realized. In this preheating device, the comprehensive effect was better when the outlet negative pressure was -50 Pa and the BOF gas flow rate was about 3 500 m3/h.