水泥窑窑体表面换热系数的计算方法

A METHOD FOR CALCULATING HEAT TRANSFER COEFFICIENT OF CEMENT KILN SURFACE

提出了一种计算水泥窑窑体表面换热系数的新方法。这种方法充分考虑了强制对流、自然对流、热辐射和窑体大小对换热系数的影响。推导了窑体表面强制对流与自然对流的换热关系式,通过互相比较得到了可忽略强制对流或自然对流的条件。结果表明,大多数情况下窑体表面的强制对流换热与自然对流换热数量级相等。因此利用向量总和法建立了混合对流换热关系式。进一步的研究发现,辐射散热所占的比例很大,采用黑度小的材料可显著降低熟料热耗。该方法的准确性优于其它方法。

A new method for calculating the heat transfer coefficient of cement kiln is proposed. The effect of forced convection, natural convection, thermal radiation and kiln size on the coefficient is considered in the method. Correlations are developed for the heat transfer in forced convection and natural convection heat transfer. The conditions neglecting forced convection or natural convection are obtained through comparison. It is shown that, in most cases, heat transfer in forced and natural convection is of the same magnitude. It is discovered in further research that a major part of heat loss is due to radiation. The heat consumption of clinker would be obviously decreased by taking advantage of low thermal emissivity materials. The new method is more accurate than the others.