固定管板式热交换器应力分析

Stress Analysis of Fixed Tubesheet Heat Exchanger

管壳式热交换器因其可靠性高、适用性广泛成为很多工业部门中应用最广的热交换器。常规设计采用GB151—1999《管壳式换热器》中当量等效近似方法,该当量等效力学模型和实际结构存在较大差异,尤其对于大型高参数热交换器,若无法应用常规设计方法,必须进行分析设计。有限元方法是最常见的分析设计方法。本文应用ANSYS通用有限元软件,对某实验台用热交换器建立了有限元模型,模型分别采用实体单元和梁、壳单元对固定管板式热交换器的壳体、管板和换热管所构成的固定连接结构进行了应力分析研究,以及温度载荷和压力载荷同时作用下的有限元分析。在实验台上进行与有限元分析中引用载荷相同的温度和压力载荷进行实验,并将实验结果与有限元分析结果进行比较,研究表明采用梁、壳单元或实体单元均能获得较精确的结果。考虑到热交换器的建模难度、工程精度需求和计算时间,对于大型高参数热交换器有限元分析采用梁、壳单元进行模拟,既可保证计算精度,又可降低建模难度,是切实可行的处理方法。

Shell and tube exchanger is widely used in many industrial fields because of its high reliability and wide applicability. In a conventional design based on the code of GB 151--1999 ＂shell and tube heat exchanger＂, a method of equivalent approximation is used. There is a great difference between the equivalent mechanical model and the actual structure, especially for large or high parameter heat exchanger. If the conventional design method fails, we must find a new method of design. The finite element analysis is the most common method. In this paper, a finite element model is built for the heat exchanger test-bed by ANSYS. The stress analysis for the fixedly connected structure of shell, tube plate and tube is carried out. In the model, the solid element and the beam-shell element are used respectively. Both models are under a same temperature load and a same pressure load. Under the same conditions, the diffrent experiments are carried out. The experimental results are compared with the results of the finite element analysis. It is shown that with both the beam-shell element and the solid element, accurate results can be obtained. Considering the difficulty of modeling, engineering accuracy and calculation time, for the large or high parameter heat exchanger, the use of the beam-shell element can ensure the calculation accuracy and reduce the difficulty of modeling. It is a practical and feasible method.