role of oil storage tank structure in the prevention emission of hydrocarbon pollution

during recent years oil products has decreased because of growing population and increasing demand to oil products and decreasing of crude oil extraction at compare to export. however, to achieve suitable levels of production, the use of improved technologies should be considered. another way to prevent the evaporation and leakage from oil storage tanks and their products are using of storage tanks. storage tank of hydrocarbons are important evaporation source of volatile organic compounds.in the present investigation the methods of hydrocarbon evaporation calculation is studied. subsequently hydrocarbon evaporation is computed from tehran's north-west storage tanks using tank-4 software. all necessary parameters which influence evaporation from storage tanks are introduced into the software. estimation of the evaporation rate of oil products from storage tanks requires comprehensive information. the required data has been provided from national iranian oil product company. tehran's north-west storage tanks is located in shahran region and provide oil products of west of tehran. there are 11 tanks, including five fixed roof and six floating roof tanks. the tanks are contained gas oil, gasoline and kerosene. ten tanks are active and one of them is under overhaul. the cylindrical tanks are with diameter of 44 meters and height of 14.64 meters. this software is designed to estimate evaporation from organic liquid storage tanks and need to specific information about tank (dimensions, construction conditions and color ...), type of liquid (chemical components and liquid temperature ...) and position of the tank (nearest city, temperature and ...) to present the evaporation from these tanks to the air. final report is included monthly and annual emission for each chemical material or combination of chemicals is stored in the tank. evaporation rate is considered from three tanks with number one, five and six, respectively containing gas oil, gasoline and kerosene.