Risk area classification for flammable gas dispersion in natural gas distribution station

The accidental release of hazardous gases can pose a significant threat to the operational safety of natural gas distribution stations (NGDS). This paper presents a methodology for classifying risk areas associated with the dispersion of flammable gases in NGDS, utilizing Computational Fluid Dynamics (CFD) simulations. Initially, a comprehensive set of scenarios for flammable gas release in NGDS is established, considering various parameters of the leak source and the wind field. The probabilities of different scenarios are estimated based on the probability of a leak occurring and the frequency of the wind field. Subsequently, a CFD model is developed to simulate the dispersion of flammable gas released within NGDS, enabling the prediction of the distribution area of the released gas. Finally, the risk areas within NGDS are classified by combining the dispersion area of the flammable gas and the probability of each leak scenario. In the case study, the area in NGDS can be classified into four levels based on the risk grades. Natural gas metering skid and natural gas pressure regulating skid module can reach level 4. The risk level in other areas ranges from levels 2 to 3. The results of risk area classification can guide the layout of combustible gas detector. It can also support emergency planning for flammable gas release incidents in NGDS.