(34a) Effective Mitigation of Cavitation-Induced Vibrations in Stg Condenser Return Lines Using CFD Analysis

This study investigates the use of Computational Fluid Dynamics (CFD) to address and resolve cavitation-induced vibration issues of the STG-3 upper condenser return line in the Ruwais industrial Complex. Initial CFD analysis identified cavitation occurring downstream of the butterfly valve as the primary cause of significant pipeline vibration, with pressure levels dropping to cavitation levels even at a 42% valve opening. To mitigate these effects, two alternative solutions were proposed: Alter-1, involving the installation of an orifice, and Alter-2, incorporating both an orifice and a 4-inch vent. The CFD results for Alter-1 showed reduced fluid velocity around the valve but continued cavitation occurring. Conversely, the Alter-2 configuration demonstrated a significant improvement, maintaining seawater pressure above cavitation levels for most of the flow path. This solution effectively mitigated the vacuum within the pipeline, reducing the incidence of cavitation. Upon implementation of Alter-2 on-site, the measured pipeline vibrations decreased from 30mm/s to 3.5mm/s, well within the allowable limit of 12.7 mm/s, thereby resolving the vibration problem. This case study highlights the effectiveness of CFD analysis in diagnosis and addressing complex fluid dynamics challenges, such as cavitation, in industrial piping system. The methodologies and findings from this study provide valuable insights and a reference framework for similar future applications. Moreover, the rigorous validation process through CFD simulations and on-site measurements highlights the robustness of the proposed solutions and underscores the practical applicability of CFD in solving real-world engineering problems.