大直径立式锥底罐变壁厚锥底结构设计

Design of wall thickness-variable bottom of large diameter vertical conical-bottom tank

针对目前没有立式锥底罐变壁厚锥底板设计公式和相关规范的现状,根据回转薄壁壳体的应力计算公式,基于无弯矩理论推导了锥底板在液压作用下的厚度设计公式。有限元数值计算结果表明,锥底罐在锥底与罐壁连接处(大角缝)应力集中程度比较严重。类比球罐设计用弧形母线回转薄壳代替原来的直线母线回转薄壳,并推导了其厚度计算公式。以3 200 m3立式锥底罐的设计为例,采用有限元软件ANSYS分别建立了两种锥底结构计算模型,并对计算结果进行对比分析。研究结果表明,弧形板锥底罐罐体应力值和变形量明显小于直板锥底罐,且大角缝处应力集中程度显著降低。此外,进行了不同长度弧形板锥底罐的数值计算,探寻了弧形板长度与应力和变形的关系。

There is no formula and regulations available for design of wall thickness-variable bottom of vertical conicalbottom tank. In this background, based on the stress calculation formula of the rotary thin-walled shell and the no bending moment theory, the design formula of conical-bottom thickness has been deduced under the hydraulic pressure. The finite element numerical calculation results show that the conical-bottom tank has a serious stress concentration at the joint of the conical bottom and the wall（large angle seam）. Analogy is made with spherical tank, with curved generatrix rotary thin shell to replace original straight generatrix rotary thin shell, and its thickness calculation formula is deduced. Taking the 3 200 m3 vertical conical-bottom tank as an example, two conical-bottom structure models are established using the finite element software ANSYS, and their calculation results are compared. The results show that the stress and deformation of the arc plate conical-bottom tank are much smaller than that of straight plate conical-bottom tank, and the stress concentration at large angle joint mitigates significantly. Moreover, the numerical calculation is made for arc plate conical-bottom tanks with different plate lengths to identify the relationship between the arc plate length and the stress and deformation.