Prediction And Analysis On The Solubility Of Water In Straight Run Gasoline

The mutual solubility of water and oil are basic properties in bulk industrial applications,such as chemical engineering,energy,environment,food,pharmacy,and so on.Reliable solubility for real mixtures provides an essential database for process design.That is,the water content dissolved in oil is not only a dominant parameter for refinery system,but also the critical operating index of oil products.Experimental measurement is the most reliable method to obtain phase equilibrium data,however,it is impossible to obtain the solubility for all kinds of systems by experiments because it is quite laborious and time-consuming.For hydrocarbon-water systems,the accuracy of the analysis and measure method determines the reliability of the data for the lower mutual solubility.Therefore,theoretical prediction can greatly improve the database for making up the shortage of measuring method.In this thesis,the COSMO-RS model was employed to calculate the mutual solubility of water and C₅^C₁₀0 hydrocarbons at different temperatures,thus allowing the investigation of the model's applicability for hydrocarbon-water system.Then,we analyzed the solubility of water in hydrocarbons and proposed a model for predicting the solubility of water in gasoline.Specifically,the mutual solubility of water and C₅^C₁₀0 hydrocarbons was calculated using BP-RI-DFT method and the TZVP basis sets,where the predicted values agrees well with the experimental ones.It indicates that COSMO-RS model is applicable for quantitatively calculating the solubility of water in hydrocarbon and that of hydrocarbons in water.According to the discussion of the influence factors on water solubility in hydrocarbon,we can drew the conclusion that water solubility is affected by two aspects.One is external conditions,including temperature and pressure;the other is internal factors,involving intermolecular forces.For hydrocarbons from different families,intermolecular forces are the main influencing factors on the solubility.The solubility of water in hydrocarbons is generally linear with the reciprocal of temperature in logarithmic coordinates,whereas the pressure has little effect on the solubility of hydrocarbon-water system.If the pressure doesn't change notably,the temperature just need to be taken into account for the solubility of water in hydrocarbons.Thus,the models of the solubility of water in gasoline was presented,including improved API empirical correlation,PNA approximation,fitting formula and ASPEN simulation are presented.There are 5 kinds of gasoline samples were selected to validate the calculation methods.It can be found from the results that the method of calculating the solubility of water in gasoline in this work is much better than the empirical correlation proposed by API,and it can be used in industry with a high reliance.