The Optimization for Installation of Air Preheater Combination Structure Based on Fluid-Solid-Thermal Coupling Model

High-temperature air preheater is an important energy-saving device during carbon black production. The expansion joint is usually installed at the external pipe connection position to prevent damage from thermal expansion. In this paper, we derived the theoretical expression of the axial stiffness of nonstandard serrated expansion joint through the axial stiffness formula of U-shaped expansion joint. Theoretical analysis showed that non-standard serrated expansion joint was better than traditional U-shaped expansion joint in terms of stiffness, principal stress, and deformation, providing a well theoretical basis for the selection of expansion joints. Then, we verified and modified the theoretical formula for the axial stiffness of the serrated expansion joint through numerical simulation, making it more accurate. Significantly, this paper proposed three different installation methods for the combined structure of serrated pipeline expansion joints. By establishing a Fluid-Solid-thermal coupling model, the response of combination structures under different installation methods under real working conditions is analyzed, and the optimal installation method is given to improve the service life of pipeline expansion joint combination structures. The results show that the installation method of guiding on both sides and constant hanging on the top produces smaller stress concentration, smaller displacement, and less likely to occur large deformation. The fluid-solid-thermal coupling model-based optimization for installation of air preheater combination structure can provide theoretical reference for engineering practice.