(166e) Thermodynamic Model of Sediment Deposition in the LC-Fining Process

In residue hydrocracking processes such as LC-FINING, sediment deposition in equipment downstream of the reaction system sometimes limits conversion and therefore, plant economics. The sediment is measured by SHFT value (Shell Hot Filtration Test), which mainly measures that portion of asphaltene that is insoluble in the oil. A solubility theory based thermodynamic model is developed to predict SHFT. According to this model, asphaltene is in equilibrium (in solution) with the surrounding fluid. The model parameters are asphaltene molecular weight and its solubility parameter. Solubility parameter is modeled as a function of the H/C atomic ratio of the heavy oil. The molecular weights are estimated from analysis of pilot plant data. The simple model is able to explain the observed trends with respect to different catalyst systems, feed sources and diluent effects. Commercial data is compared with the pilot plant data and the model prediction.