Determination and Dispersion Modeling of VOC Emissions from Liquid Storage Tanks in Asalouyeh Zone

There are many environmental challenging problems for environmental scientists in Asalouyeh which is located in the south of Iran. In Asalouyeh zone, a large number of petroleum, petrochemical and natural gas industries are operating and as side effect air pollution is one of the most challengeable problems in this industrial area. Therefore, efficiently reduction and control of air pollutants are the most important programs for related organizations. In order to reduce emissions of air pollutants and their effects it is necessary to recognize the amount and spatial dispersion of air pollutants. Volatile organic compounds (VOCs) are one of the most significant pollutants in this industrial area and organic liquid storage tanks are one of the emission sources. Hence in this paper, evaporative losses of the stored liquids from tanks of an oil company in Asalouyeh zone are determined using storage tank emissions calculation software (TANKS 4.0.9d) and the dispersion of volatile organic compounds (VOCs) emissions from liquid storage tanks are simulated by AERMOD dispersion model. In this research, 16 tanks containing organic liquids are considered and dispersion of their VOC emissions are simulated over an area with dimension of 1515 km2 with resolution of 150 m. Results for concentration of VOCs are presented at 5 vertical layers including ground surface, 2 m, 10 m, 20 m and 30 m layers. Model is run for 12 months meteorological data (year 2009) and results are presented for 1 hr, 3 hr, 8 hr, 24 hr, 1 month, and 12 months averaging concentrations of VOCs.