Pollutant Dispersion: Oil Storage Tank Explosion

Description

Explosions in oil storage tank farms represent a persistent safety hazard in reacting flow modeling, where a rapid, energetic chemical reaction consumes fuel and releases heat along with multiple gaseous combustion products into the surrounding environment. This CFD study uses ANSYS Fluent to simulate the explosion of oil storage tanks and the subsequent dispersion of combustion pollutants across an urban area, addressing a real safety concern for regions where tank farms sit close to residential neighborhoods and industrial units. The analysis evaluates how far and in what concentrations explosion-generated pollutants such as carbon dioxide and other combustion gases reach the surrounding population, providing a basis for risk assessment and emergency planning.

Methodology

The three-dimensional urban domain, measuring 6.6 km in length, 4.6 km in width, and 200 m in height, is built in Design Modeler and includes a dedicated zone containing eighteen cylindrical oil tanks alongside separate zones representing residential and industrial districts. The domain is discretized with an unstructured mesh of 1,746,979 elements. Because the explosion involves chemical reactions among several gaseous constituents, the Species Transport model forms the core of the setup, tracking seven species — CO₂, SO₂, NO₂, CO, H₂O, C, and air, with air serving as the background fluid. The explosion is represented through defined energy and mass sources within the tank region: a heat source of 139,072.7 W/m paired with production rates for each pollutant, including CO₂ at 0.1358 kg/m³·s, H₂O at 0.0679 kg/m³·s, CO at 0.0047 kg/m³·s, SO₂ at 0.000131 kg/m³·s, C at 0.0068 kg/m³·s, and a small NO₂ contribution. Wind-driven dispersion is captured by setting the northern and western domain faces as airflow inlets and the eastern and southern faces as outlets, with air entering at 300 K and 20 m/s directed at a 60° angle, decomposed into corresponding x- and y-velocity components.

Results Analysis

The simulation produces three-dimensional contours of temperature and of the volume fraction for each gaseous species throughout the domain. Results show that the released pollutants are carried by wind into the surrounding residential and industrial zones, confirming potential population exposure following such an explosion event. The study demonstrates how species transport combined with defined energy and mass sources can reproduce the generation and atmospheric spread of combustion products, offering a practical basis for evaluating explosion hazards and informing the siting, spacing, and protection of facilities located near populated areas.