Análise CFD de defletor de flange na dispersão de nuvens de hidrocarbonetos

Abstract

This work presents an evaluation of the effectiveness of a flange deflector or protector in dispersing clouds containing hydrocarbons on offshore oil and gas production platforms, using computational fluid dynamics (CFD) techniques through the Ansys Fluent software. The research aims to contribute to improving risk analyses and consequence studies in scenarios involving flammable gas leaks. The study investigates whether a rectangular-shaped flange deflector can direct the hydrocarbon cloud in the opposite direction of the leak, even under wind conditions that favor the leak direction. The deflector is designed without one of its walls to avoid the confinement of explosive gases. The representative leak has a circular section with a diameter of 1 inch, consists of pure methane, and the pipeline process data are a pressure of 2 MPa and a temperature of 100 °C. The study begins with a comprehensive literature review on operational risks, gas dispersion in offshore environments, and CFD modeling applied to industrial safety scenarios. The mathematical modeling and the models used for the CFD analysis are also discussed. Next, a methodology is developed for the geometric model representing a typical pipeline section on a platform, a flange, the leakage area, and the proposed flange protector. The analysis of the results assesses whether the methane mass fraction contours and 20% LFL (Lower Flammability Limit) methane isosurfaces, under wind speeds of 0, 0.5, 1, 2, 3, and 4 m/s, are not directed along the leak path, indicating that the flange deflector successfully guided the cloud in the opposite direction. The study’s conclusions highlight the importance of flange protectors as a risk mitigation measure on offshore platforms, quantifying their effectiveness in reducing hydrocarbon cloud dispersion. Finally, directions for future research are suggested, including the investigation of innovative geometric parameters for flange protectors, the influence of pipeline process data (pressure and temperature), the influence of different types of leaks (position and shape), and fluid-structure evaluation to assess impacts on the flange deflector.