(32r) Gas Dispersion from Cargo Tank Inerting Systems into Accommodation Air Intakes on Offshore Production Units: A CFD Study

Global economic and social progress has fueled an increase in energy demand, driven primarily by fossil fuels such as oil and gas (O&G). Despite the increasing adoption of renewable energy, the International Energy Agency predicts a 35% increase in global demand for O&G between 2010 and 2040. To meet this growing demand, O&G companies are venturing into increasingly complex environments, such as ultra-deepwater. These operations pose significant safety risks, including gas leaks, fires, and explosions, which can lead to serious human injuries, environmental damage, and structural failures. This paper focuses on analyzing the risks of asphyxiating and toxic gas leaks, as well as deflagration incidents, on a fixed deepwater platform in Brazil. These often overlooked risks can have catastrophic consequences. Furthermore, the history of toxic gas leaks in offshore production units affecting workers underscores the importance of this research. The main objective of this study is to analyze potential gas leak scenarios on an FPSO, which may result in injuries to individuals and, depending on the boundary conditions, the leaked gas cloud may reach the air intakes that serve the air conditioning system, escalating the severity of the accident scenario for the people on board. The CFD Flame Acceleration Simulator (FLACS) code was employed to predict the hazardous loads resulting from the selected leak points. FLACS solves the compressible Reynolds-Averaged Navier-Stokes (RANS) equations on a three-dimensional Cartesian grid. The entire chain accident scenario was simulated, ensuring the conservation of mass, momentum, enthalpy and mass fractions of species. The use of a CFD tool allows the identification of the behavior of the gas cloud formed by the leak and the assessment of the need for recommendations for the impacted areas. To accurately determine the composition of the leaked gas, mass and energy balances were simulated using the commercial process simulator Unisim.