Determination of the emission rate and modeling of benzene dispersion due to surface evaporation from an oil pit

Air pollution is considered as one of the important challenges in oil fields and, determination of the emission levels and to identify the way of their dispersion is the first step to control and reduce the air pollutants more effective and efficient. The objective of this study was to determine the emission rate and analysis of VOCs due to surface evaporation from oil pit at one of the petroleum companies. This study was conducted in four seasons in 2017 on the Kharg island. The environmental benzene from the pit surface was measured then, dispersion method, analysis of the emissions of these pollutants was conducted using TANKS 4.0.9d and AERMOD dispersion model in an area of 10×10 km2 with a network spacing of 200. The maximum average concentration of airborne benzene at station A (0.53 ppm) and the station H (0.59 ppm) were obtained in the spring and, station M (0.72 ppm) and the station P (0.81 ppm) were obtained in the summer which are higher than the standard limit determined by DOE and EPA. The rate of emission from the oil pit was calculated as 0.0012 g / s. The motion of the pollutant plume is from the average hourly to yearly direction to the south and the results shows that the pollutant plume is moving in the direction of the wind,and because of low height of source of pollutants, the pollutant plume has remained in the oil pit area and has not moved. In general, considering the estimation of predictions, theperformance of the AERMOD dispersion model can be considered acceptablein predicting the concentration of benzene in the target area