Study On Quantitative Estimation Methods For Fugitive Emission From Tanks In Petrochemical Industry

As a pillar industry in the national economy, petrochemical industry supplies the oil and chemical products which are necessary for social development. But at the same time, it’s also one primary industrial pollution source. The air pollution is mainly in the form of fugitive emission, with the major pollutants of various high-concentration Volatile Organic Compounds (VOCs) and especially multifarious Hazardous Air Pollutants (HAPs), which bring great harm to the ecological environment and human’s health. Tanks are widely used in the petrochemical plants and they are also one of main fugitive emission sources, so it is significant to have research on methods of fugitive estimation for Tanks in petrochemical plants.The research project aims at: (1) Analyzing the key parameters which impact the loss from fixed roof storage tanks and floating roof tanks, in order to provide basis for estimation research and developing technology to reduce emissions; (2) Establishing a working procedure to estimate the fugitive emissions of VOC for existing petrochemical plants, in order to provide methods for auditing atmospheric pollution sources and planning regional environment; (3) Deducing a new VOC-emissions-from-Tanks estimation method which is suitable for domestic petrochemical plants under construction, in order to provide technical means for environmental impact assessment. For fixed-roof tanks, working loss takes 80-90% of the total emissions and the key parameters include: turnovering times per year (N), working loss product factor (K_p) and vapor pressure (P_v). Standing storage loss takes 95% of floating roof tanks emissions. The key parameters of standing storage loss from external floating tanks include types of rim seal system and wind speed (v).The key parameter of working loss is shell clingage factor (C); The key parameters of standing storage loss from internal floating roof tanks include liquid property (including Species, Vapor Pressure (P_v) and Molecular Weight (M_v)).The key parameters of working loss include: shell clingage factor (C) and number of turnovers per year (N).On the basis of the on-site investigation and analysis on the storage and transferring program in petrochemical plants, the dissertation establishes a working procedure to estimate the fugitive emissions of VOC for existing petrochemical plants: Choosing a working object, investigating and analyzing, confirming estimation method, establishing data form, collecting data, computing with models and analyzing results. At the same time the dissertation compiles Tank information tables suitable for actual production status and solves common problems in the application process. Take Shanghai Petrochemical Company as an example, the total VOC emissions achieves 803.95 ton per year.The feasibility report of newly constructed petrochemical project often includes the types and yield (consumption) of major raw materials and products. The dissertation chooses suitable type for Tanks according to the lighting points of organic liquid. On the basis of Clapeyron equation and considering key parameters of working loss, the dissertation deduces annual total emission from fixed-roof tanks. The estimation of floating roof tanks is on the basis of global experience in petrochemical storage and transportation, to set the norm tank for internal and external floating roof tanks, and to calculate the total emission of norm tank with method recommended by EPA. Tank farm cubage is calculated according to the consumption and production of storage liquid, and annual total emission is achieved in the setting that only norm tank is applied in the tank farm.Total fugitive emission is dearth of proper monitoring technologies tobe validated, so the dissertation compares my method with the other onewhose quality has been certificated. Take Shanghai PetrochemicalCompany as a test and comparing with TANK software, the result of mymethod has windage of 10.02%, which proves that my method is efficientand accurate. Comparing with the newly developed measure by RTI andEPA, the emission of oil refining with my method has windage of 9.7%,which proves that the parameters deduced by this dissertation is rational.