大型回转窑筒体结构的力学行为分析

ANALYSIS OF THE MECHANICAL BEHAVIOR OF A LARGE ROTARY KILN SHELL

运用理论分析和有限元技术,研究复杂重载、多支承、变刚度和超静定的大型回转窑筒体结构力学行为。基于超静定连续梁模型和赫兹理论,计算筒体支撑与摩擦载荷以及轮带与托轮的接触压力和面积,为筒体有限元建模提供边界条件。综合考虑多个附件对筒体载荷与刚度的复杂影响。通过定义当量密度等效处理重力载荷。由于耐火砖层的松散堆砌特点,在含耐火砖筒体模型中,若将耐火砖作为整体赋以砖块刚度与实际不符,故将弹性模量赋以小值,以减弱其刚度影响。首次解析推导出耐火砖对筒体的压力分布公式,建立效率更高、不含耐火砖的函数加载筒体模型。两种模型相互验证地分析筒体的变形和应力状态,并与文献中同类回转窑的应力结果接近。结果表明,回转转矩和摩擦阻力对筒体变形及应力的影响很小;筒体应力最高和横截面圆度最差的薄弱部位均在中间档支承处,解释了掉碎砖现象和潜在安全问题的发生机理,且与该窑体的维护记录相符。文中分析方法和结果对回转窑筒体的安全评估、补强设计和窑线调整均有参考价值。

The finite element method is applied to analyze the mechanical behavior of a large heavy, multi-supporting, and statically indeterminate rotary kiln shell equipment with varying rigidity. Based on the statically indeterminate continuous beam model, the supporting and friction loads of the kiln shell are calculated, and the contact pressure and areas between the support wheels and kiln tires are obtained as well. These investigations are the preparation of boundary condition data for the FE（finite element） modeling of the shell. The equivalent effect of the various attached structures of the shell on its stiffness and loads is taken into account properly. The weight loads of various attachments are realized in the FE model via the definition of the equivalent density. The layer of firebrick should not be treated as an integrated firebrick structure because of its loose stack characteristic. Therefore, the elastic module of the layer of firebrick is selected as a small parameter to weaken the stiffness effect. Furthermore, a new functionally loading FE model with more efficiency, which eliminates the layer of firebrick, is built up by means of deducing an analytical solution for the pressure loads of the layer of firebrick on the inner surface of the shell. Numerical results of the shell deformation and stress calculated via the two models are in good agreement, which indicate that the rotary torque and friction have little influence on the stress and deformation of the shell; the maximum equivalent stress and the worst circularity of the cross section are at the same location close to the and kiln tire. The mechanisms are also interpreted for the potential safety problems and the phenomena of firebrick fall or broken. The results serve as instructions for the design, repair and the axis alignment of the rotary kiln shell.