Simulation of Flammable and Toxic Gases Released from Condensate Storage Tank in a Gas Plant Based on Elevation Change

The release of hydrocarbon and toxic vapor from atmospheric storage tanks is considered as a hazardous phenomenon in the chemical and process industries. Most often, detailed meteorological data for a particular location are unavailable, making the application of Pasquill’s atmospheric stability table the only choice for running simulations. The simulation of the flammable and toxic vapor release and cloud dispersion in South Pars, Iran in the 4th Gas plant incident in 2012, is run by applying the PHAST 6.53.1s/w. Meteorological data extracted from Pasquill's stability table. A simple methodology is developed for assessing land elevation difference between release source and gas detectors the obtained results are validated against time and location of recorded alarms in the site. The atmospheric parameters applied in this simulation are compared with wind speed and sky cloudiness data received from the Iranian meteorological institute. The Pasquill's parameters applied in this simulation are verified against local meteorological recorded data. The results indicate that if the vapor cloud is close to the earth's surface before any major change in the land elevation, this change can be neglected. Sensitivity analysis reveals that there will be fewer consequences if atmospheric discharge direction has a vertical upward orientation.