圆环形对撞流干燥器的流体动力学特性分析

Analysis of hydrokinetics characteristics in circular impinging stream dryer

为了得出颗粒状物料在对撞流中的运动规律 ,以及对撞流干燥器加载后流动特性的变化规律 ,设计了圆环形对撞流干燥试验台 ,并进行了流动特性的试验研究。试验测定了系统压力降随载带率的变化情况 ,并利用高速摄影技术 ,对颗粒物料在对撞室内的运动速度沿运动方向的变化规律进行了分析。建立了物料颗粒的动力学模型 ,计算了颗粒在对撞室内的穿透深度 ,并将计算结果与试验结果进行了对比。结果表明 ,颗粒动力学模型计算结果与试验结果基本吻合 ,能较好地反映颗粒在对撞区内的流动特性。同时 ,该模型可用来确定加速管长度和端面距离、颗粒平均滞留时间等干燥器重要参数。另外颗粒在对撞区内作减幅振荡运动 ,在第一次振荡时气固相对速度较大 ,干燥强度最高。

In order to study the movement of granular material in impinging stream and the flowing characteristics of material in impinging dryer during drying, a circular impinging stream dryer was designed, and experiments were also carried out with the dryer. Variations of the system pressure drop versus ratio of material taken were measured. The material velocity variation along its movement direction was analyzed with high speed photograph camera. Kinetic model of the material was developed, and the material penetration length and its velocity at various positions were calculated. The calculated results agreed well with the experimental results, thus the model can be used to analyze the flowing characteristics in impinging dryer. This model can also be used to obtain parameters, such as accelerating pipe length, the distance between end faces, mean residence time of particle, etc.. Moreover, the particles vibrated with damping amplitude in the impinging section, and during the first vibration, drying rate was the highest with high relative velocity between the airflow and the particles.