Dilution Effects of a Steam Curtains on an Accidental Dense Gas Release

Accidental releases of dense gases represent a critical hazard in the process industry due to their tendency to form ground-hugging vapor clouds with limited vertical dispersion. Substances such as isobutane, chlorine, and liquefied natural gas may generate clouds denser than ambient air, whose behaviour is governed by the balance between gravitational slumping and turbulent diffusion. After an initial collapse, dense gas clouds spread radially in a stratified layer, exhibiting a liquid-like creeping motion along the terrain and accumulating in low-lying or confined areas. Under weak wind or stable atmospheric conditions, dilution is strongly limited, leading to persistent hazardous concentrations at ground level. In such scenarios, upward‑directed steam‑curtain systems, which rely on high‑momentum flows to entrain and dilute flammable gases, may experience reduced effectiveness, particularly when obstacles or ducts are located near the release zone. Steam curtains are active mitigation devices that promote air entrainment through high-velocity vapor jets, combining aerodynamic, turbulent, and thermal effects. In this work, computational fluid dynamics simulations were performed using ANSYS Fluent® to investigate the interaction between a dense gas cloud and an industrial steam curtain system implemented in the BASF® facilities in Ludwigshafen am Rhein (Germany), with the aim of analysing the key mechanisms and variables influencing mitigation performance.