Effect of Leak Diameter and Season on Flammable Cloud Mass in Consequence Analysis: A Process Facility Case Study in Abadan, Iran

Seasonal meteorology can shift the extent of a flammable cloud and therefore alter vapour cloud explosion (VCE) consequences. This paper investigates the combined influence of leak diameter and seasonal ambient conditions on the flammable cloud mass predicted in PHAST for a real process equipment located in Abadan, Iran. A hydrogen-rich process gas (H۲/CO/CO۲/CH۴/N۲, water-saturated) at ۲۲ barg and ۴۰ °C is considered. Seasonal inputs (temperature, relative humidity, and mean wind speed) were derived from the ۲۰۲۴ daily historical archive of Weather Underground and aggregated to seasonal representative values; atmospheric stability was held constant at class D to isolate seasonal effects attributable to the meteorological inputs. PHAST flammable mass outputs were evaluated as a function of distance to the explosion centre, and consistent comparisons were ensured by using the common distance range shared by all seasons. A focused diameter sweeps around the transition region (۴۵–۴۹.۵ mm) shows that winter consistently produced the minimum flammable mass over the common distance range, while the season associated with maximum flammable mass shifts from spring-dominant behaviour at ۴۹.۰–۴۹.۲۵ mm to summer-dominant behaviour across the full distance range at ۴۹.۵ mm. The identified transition supports defensible selection of conservative seasonal scenarios in consequence analysis for similar hydrogen-rich gas releases.

کلیدواژه ها:

Consequence analysis ، PHAST ، vapour cloud explosion ، flammable mass ، seasonal meteorology ، leak diameter ، Abadan