铁矿粉预还原回转窑气固三维传输行为

Three-dimensional Flow and Heat Transfer Behavior of Gas-Solid inIron Ore Powder Pre-reduction Rotary Kiln

采用数值模拟方法先讨论煤气、物料物性参数以及回转窑运行参数对窑内煤气和物料运动特性的影响规律,再探讨其对窑轴向煤气温度变化趋势和窑横截面温度变化趋势的影响规律。研究表明窑内煤气螺旋式前进,煤气温度在距离窑头0~15 m下降速度较快,随后变缓。随煤气喷吹速度的提高,窑内煤气温度提高。窑内物料体积分数分布呈S形。回转窑倾角过大导致物料颗粒最大速度远离中心弦位置;回转窑转速提高促使物料颗粒最大速度更接近中心弦位置。窑截面温度先平缓降低后迅速下降最后趋于平缓。合理的铁矿粉预还原回转窑工艺和结构参数为:物料质量流量13.88 kg/s、煤气进口风速16 m/s、回转窑倾角3°、回转窑转速0.6 r/min。

In this paper,the influence of physical parameters of gas and material as well as rotary kiln operating parameters on the motion characteristics of gas and material in the kiln were discussed firstly with the numerical simulation method,and the influence on the gas temperature distribution along kiln axial and the kiln cross-sectional temperature distribution were discussed in order to provide theoretical guidance for the pre-reduction process of iron ore powder rotary kiln.The study shows that the gas temperature in the kiln increases with the increase of gas injection velocity.Too large inclination angle of the rotary kiln causes the maximum velocity of material particles to be far from the position of the central chord.The increase of rotational velocity of the rotary kiln impel the location of maximum velocity of material particles to be close to the central chord.Excessively high gas injection velocity or material mass flow are negative to promote the heat exchange process in the kiln.Reasonable process and structure parameters of iron ore powder pre-reduction rotary kiln are as follows:material mass flow of 13.88 kg/s,gas inlet velocity of 16 m/s,rotary kiln inclination of 3°and rotary kiln rotational velocity of 0.6 r/min.