考虑保温箱作用的电除尘器壳体顶梁结构优化设计研究

对电除尘器壳体顶梁结构提出了一种优化设计思路:即将保温层与原壳体箱形截面顶梁组合成一个桁架梁系,增加了梁系的整体截面高度,使桁架梁系的抗弯承载能力比原壳体顶梁大幅提高,从而可以减小原箱形截面顶梁的壁厚,以节省钢材。为了研究桁架梁系的设计方法,结合一实际工程,首先,分别采用基于平截面假定的平面梁杆结构体系计算方法和壳单元空间有限元方法对桁架梁系进行内力分析。结果表明,采用平面梁杆结构体系计算方法得到的内力结果是基本准确的。其次,分析外界、保温箱与壳体之间气压差分布以及温差对桁架梁系的荷载作用,得到了最不利的气压差和温差荷载工况。第三,优选桁架梁系构形,在下弦构件集中力作用点处设置竖腹杆,且区格分布较为均匀的构形是较为经济合理的。考虑保温箱的承载作用,将原壳体顶梁优化改造为桁架梁系后,既能保证其承载安全可靠,又能明显节省钢材。

Optimizing Design Study of Top Beam Structure of Electrostatic Precipitator Casing in Consideration of Thermos Cabinet Structural Contribution

An optimizing design idea is produced for the structure of top beam of electrostatic precipitator casing. The thermos cabinet and the original box shaped top beam of casing compose a truss beam system whose overall section height is increased greatly, resultantly, the bend bearing capacity of truss beam increases significantly than that of the original top beam of casing. Consequently, the wall thickness of box section of the original top beam can be reduced so that the steel consumption can be saved. In order to investigate the design method of truss beam, on the basis of a practical project, firstly, the internal force analyses of truss beam are conducted respectively by different methods, including the evaluation method for plane structural system composed of beam and link based on the plane section assumption, and the spatial finite element method based on shell elements. The results comparison indicates that the evaluation results from the method for plane structural system of beam and link are basically accurate. Secondly, the load effects on truss beam are investigated respectively, including the air pressure difference and the temperature difference among external layer, thermos cabinet and interior of casing. The unfavorable load cases of air pressure difference and temperature difference are proposed. Thirdly, the selective preference of truss beam configuration is conducted. The configuration is comparatively more economical whose vertical members are located on the concentrated force action points of bottom member and blocks distribute more uniformly. In consideration of load bearing effect of thermos cabinet layer, the optimized design of truss beam originating from box sectioned top beam can not only ensure the truss works safely but also reduce the steel consumption significantly.