زهره خلیفات

Multi-phase gravity separators are one of the most useful equipment used to separate immiscible phases in different industries. Debottlenecking of the separation process was investigated in this study, to improve the performance of an industrial three-phase boot separator. So, the effect of altering the inlet diverter (replacing the slopped inlet diverter with a vane inlet diverter), placing a baffle at the middle, and placing a mist extractor at the end of the separator, were considered. Results of this research showed that by using the new design, the performance of the separator improved so that the liquid amount at the gas outlet decreased by 83.8% compared to the current design of the industrial separator. This new design was successful in improving the flow behavior at the inlet zone, improving the droplet size distribution at the outlet zone, and preventing the impressive decrease of the separator performance while increasing the inlet flow rate.

Gravity multiphase separators are one of the most important equipment in different industries. Due to the limitations related to semi-empirical models and the high-performance cost of experimental tests in finding the optimized design, computational fluid dynamics (CFD) has been widely used recently. In this research, after a total review on gravity separators, a review of CFD studies on these apparatuses, to find the appropriate model for simulation and optimization, are considered. Results show that, although CFD is a powerful technique for modeling and improving the separator design, some disadvantages like using incorrect models, simplified assumptions and inappropriate optimization methods lead to inaccurate simulation and optimization results, which should be considered in future works.

Three-phase separators are used to separate immiscible phases in petroleum industries. Computational fluid dynamics (CFD) simulation of industrial separators are rather limited in the literature and most of them are based on Eulerian-Eulerian (E-E) or Eulerian-Lagrangian (E-L) approaches with poor agreement between simulation and industrial data. In this research a coupled E-E and E-L method, i.e., the combination of the volume of fluid (VOF) and dispersed phase model (DPM) was developed to simulate an industrial three phase boot separator. Noted that despite the wide usage of boot separators in petroleum industry, no research has been performed on it. In order to develop the coupled model, effects of different sub-models including virtual mass force, droplet break up and also discrete random walk (DRW) model which was ignored in most of the researches, were considered. Liquid droplet entrainment in the gas outlet taken from data of Borzoyeh Petrochemical Company in the south of Iran, was the criteria for evaluating the CFD model. It is concluded that the coupled model using three mentioned sub-models with the high importance of applying DRW, is a successful way in predicting the separator efficiency so that considering all sub-models decreases the simulation error from 40.81% to 12.9%. Using the validated model, effects of inlet droplet size and flow rate on the separation performance were considered. Results demonstrated that decreasing droplet size (by 20%) and increasing flow rate (from 5800-6475 kg/hr), decreased the efficiency, such that the liquid entrainment in the gas outlet increased by 29% and 38 % respectively

Multiphase separation in gravity separators is one of the important processes in different industries. This study presents a computational fluid dynamics (CFD) simulation of an industrial three-phase boot separator applying a coupled volume of fluid (VOF)- dispersed phase model (DPM) method for hydrodynamic analysis and troubleshooting of the separation process. Noted that despite the wide application of the boot separator in different industries, no research has been performed on this type of separator to investigate the macroscopic and microscopic behavior of the separation process. The results of numerical calculations based on three-phase flow profile, secondary phase behavior, separator performance, and size distribution of the droplets were investigated in this research. Results showed that the CFD model is well capable of estimating the separation behavior in a threephase boot separator. Troubleshooting of the studied separator was also investigated to detect the parameters that might decrease the separation performance. Based on the results, it is concluded that the separator suffers from the type of the inlet diverter, lack of an efficient mist extractor at the gas outlet and also lack of an appropriate vortex breaker at the oil outlet. The effect of increasing the inlet water flow rate on the separator performance was another parameter that was studied in this research. Results demonstrated that increasing the inlet water flow rate from 11823-47295 kg/hr caused an increase in the mass of droplets at the gas outlet from 0.09 to 1.6 kg/hr, but this increase did not lead to a significant decrease in the separation efficiency.