弹性大补偿密封作用下储罐钢制双盘式浮顶的受力特性

中石化安全工程研究院有限公司 • 化学品安全全国重点实验室

大型储罐;浮顶;弹性大补偿密封;桁架;应力分布;罐体变形

Mechanical characteristics of steel double-deck floating roof for storage tank under the influence of elastic sealing structure with high compensation capability
ZHANG Ruiyu,ZHANG Yuping,SUN Mingyuan,LI Rongbin,WANG Shiqiang,TAO Bin

SINOPEC Research Institute of Safety Engineering Co., Ltd.//State Key Laboratory of Chemical Safety

large storage tank, floating roof, elastic seal with high compensation capacity, truss, stress distribution, tank deformation

DOI: 10.6047/j.issn.1000-8241.2025.01.008

备注

【目的】随着环保排放要求的日益严苛,全接液浮顶与大补偿密封逐步在浮顶罐上使用,在边缘密封、罐壁变形等因素共同作用下,浮顶受力情况复杂且破坏、卡盘等事故时有发生。研究弹性大补偿密封作用下浮顶的受力特性,对保障浮顶安全运行具有重要意义。【方法】设计并搭建了储罐密封效能测试平台,测试不同环形间隙下弹性大补偿密封对浮顶的作用力。基于有限元方法建立了5×104m3储罐双盘式浮顶有限元分析模型,开展正常运行、罐壁变形及极端卡盘工况下浮顶应力与变形分布特性研究,分析了多工况下浮顶的应力集中薄弱区。【结果】随着环形间隙的缩小,大补偿密封结构的压紧程度提升,与罐壁接触区域逐渐上移,浮顶所受摩擦力显著增大;当储罐正常运行时,最大Mises应力位于桁架结构,应力集中区域为靠近底板侧横梁与加强筋的连接处;当罐壁发生椭圆化变形或存在局部变形时,局部卡阻处浮顶变形量增加,当浮顶所受平均摩擦力接近时,储罐的局部变形相比椭圆化变形更易导致浮顶卡盘与失稳;在卡盘工况下,浮顶所受最大Mises应力显著增大,且在极端卡盘条件下浮顶所受应力超过其许用应力,易造成局部强度破坏。【结论】对于存在罐壁变形的储罐,在对其加装高效密封或进行密封改造时,应开展浮顶力学性能评价工作,以确保浮顶储罐的安全运行。(图 14,参[26]
[Objective] With increasingly stringent emission requirements for environmental protection, more floating roof tanks are being equipped with full-contact floating roofs and sealing structures with high compensation capacity. However, these floating roofs are subjected to complex stress conditions due to the combined effects of factors such as rim sealing and tank wall deformation. This situation leads to increasing incidents such as damage and deck jamming. To address these issues, studying the mechanical characteristics of floating roofs under the influence of elastic sealing systems with high compensation capacity is crucial for ensuring their safe operation. [Methods] An experimental platform for evaluating the sealing efficiency of storage tanks was designed and constructed. This platform was subsequently used to assess forces exerted by elastic sealing structures with high compensation capacity on floating roofs with various annular gaps. Utilizing finite element methodology, a finite element analysis model was established to simulate double-deck floating roofs for 5×104 m3 storage tanks. This model was employed to study the stress and deformation distribution characteristics of floating roofs under normal operation, tank wall deformation, and extreme deck jamming conditions. Further analysis focused on identifying weak areas within these roofs due to stress concentration under various conditions. [Results] As the annular gaps narrowed, the sealing structure with high compensation capacity became increasingly compressed, resulting in progressively upward-moving contact areas with the tank wall and a significant increase in the friction force acting on the floating roof. During normal operation, the maximum Mises stress was identified within the truss structure, with stress concentration occurring near the connection between the side beam and the stiffener of the bottom plate. Elliptical or localized deformation in the tank wall led to expanded deformation in the floating roof area, where localized jamming occurred. Under similar average friction forces acting on the floating roof, localized deformation in the storage tank was more likely to cause deck jamming and instability of the floating roof than elliptical deformation. Under deck jamming conditions, the maximum Mises stress experienced by the floating roof increased significantly, and under extreme deck jamming conditions, the stress exceeded the allowable limit, resulting in localized strength failure. [Conclusion] For tanks with wall deformation, mechanical performance evaluation should be carried out on their floating roofs to ensure safe tank operation before installing additional high-efficiency seals or undertaking sealing renovations. (14 Figures, 26 References)
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