Mechanical Study On Fixed Tubesheet Of Tubular Heat Exchangers And Calculation Of Thickness Of Double-Tubesheets

Tubular heat exchangers are widely applied in the petrochemical, energy industry and so on. For a tubular heat exchanger, tubesheet is an important pressurized part, which plays an important role in the rational design of the equipment for enhancing the safety, saving materials and facilitating manufacture process. Based on the present design codes, the calculated tubesheets are usually thick with heavy weight and the double-tubesheets are also designed conforming to the traditional tubesheet design codes, which is obviously not so rational. In this thesis, finite element analysis was performed for the mechanical behaviors of the fixed tubesheet.Firstly, a FEA model of tubesheet on a fixed tubesheet heat exchanger was established. Effects of size of the unpierced part, thickness of the tubesheet, thickness of cylindrical shell and boundary conditions on the strength and deflection of the tubesheet are studied. It is found that the number of tubes makes a big contribution to the strength of the tubesheet. The transition or concave chamfer angle structure at tubesheet-to-shell junction could reduce the maximum stress intensity at the tubesheet and the bending stress intensity at the center part, but the radius of concave chamfer angle must be limited.Secondly, the thickness of the tubesheets in a double-tubesheets heat exchanger was designed according to GB151-2012(draft) and also FEA. The results show that using FEA, the thickness of the inner tubesheet can be greatly reduced. Meanwhile, parametric analysis of double-tubesheets’ structure shows that the distance between adjacent tubesheets L has a huge effect on the stress intensity at the center of the tubesheet, and the variance of temperature difference ΔT between the inner and outer surfaces of tubesheet would cause remarkable fluctuation of the tubesheet bending stress intensity.Finally, based on VB programming language and ANSYS finite element analysis software, a software for the assessment of the tubesheet strength in a fixed tubesheet heat exchanger has been developed, which could conduct the finite element analysis of the tubesheet with specific structure through an interactive interface, and generate stress analysis report automatically.