回转窑内物料传输模型的研究

回转窑内物料平均停留时间（MRT）直接决定物料化学反应程度，它是回转窑设计的重要依据之一。在回转窑实验台上对5种不同的固体废弃物料和窑内风速、回转窑转速和回转窑倾角及物性参数改变的情况下进行了实验，获得了不同工况下物料MRT的变化规律：随着回转窑转速的提高、倾角增大和窑内风速增加，MRT减小；物料的物性参数中，休止角对MRT影响较大，休止角大的MRT小，而密度的变化影响相对较小。MRT对于以上各影响因素的敏感性差别也较大：回转窑转速对MRT影响是比较敏感的，特别是转速较小时；转窑倾角对MRT的敏感性则比较均匀；窑内风速在小回转窑转速、低窑内风速时对MRT的影响较为敏感。针对回转窑内物料传输影响因数众多、非线性机理强烈的特性，建立风速条件下物料传输模型（MMCAV），并在回转窑转速倾角和一定风速条件下对模型进行了验证。在次高倾角（α=4.56°）时，MRT随窑内风速变化的情况，其中最大相对误差为7.1％。在低窑转速和高风速情况，总的平均相对误差为2.81％。用稻壳作为输运物料，把实验数据与Perry等模型对比发现：Perry模型在c=0m/s时，Saeman模型在c=0.41m/s附近时与实验值差异较小。风速的影响范围与回转窑倾角有较大关系，倾角α=3.04°时，风速c>0.41m/s必须考虑风速对物料输运的影响；而倾角α=4.56°时，c>0.25m/s就应考虑风速的影响。

Research on the Model of Transport Process in Rotary Kiln

Abstract: The mean residence time (MRT) of particles in rotary kiln affects the chemical reaction of particles directly and it is one of the most import factors for rotary kiln designing. The variation rules of MRT for five different kinds of solid wastes are experimentally studied under changing kiln rotational speed, inclination angle, air velocity inside the kiln and physical properties of raw particles. With an increase of rotational speed, inclination angle and air velocity inside the rotary kiln, the MRT will decrease. The influences of physical properties of particles on MRT are different, a greater repose angle will lead to shorter MRT, but the change of density of particles leads to less change of MRT. The responses of MRT to the factors mentioned above show great differences among them: the kiln rotational speed is comparatively sensitive, especially when the kiln rotational speed is low; the sensitivity of kiln inclination angle to the MRT appears a relatively uniform character; as regards air velocity in the kiln, a combination of low kiln rotational speed and low air velocity inside the kiln is rather sensitive. Many factors can affect the transportation of particles in the rotary kiln and the change of MRT shows nonlinear feature. The MRT model consider air velocity (MMCAV) has been developed and validated under certain kiln rotational speed, slope angle and air velocity. The results show that at the second high slope angle α=4.56°, the maximum relative error that MRT varies with air velocity in the kiln is 7.1%; and under the condition of low kiln rotational speed and high air velocity in the kiln, the total relative error is 2.81%. When rice shell is used as a transport particle, there are no great difference between the experimental date and the predicted values from Perry model as c=0m/s or from Saeman model as c=0.41m/s. The affecting range of air velocity in the kiln has intense relation with rotary kiln inclination angle. When inclination angle α=3.04°, the effect of air velocity on particles transport must be considered as c>0.41m/s; whileα=4.56°, the effect should be considered as c> 0.25m/s.