فهرست مطالب amir hossein nikoo

Hydrocarbon fouling of preheat exchangers causes several detrimental impacts on operation, environment, safety, as well as economy of oil refineries. To investigate threshold fouling models, a variety of hydrocarbon fouling data, such as temperature, oil flow, fluid properties, and geometries of such exchangers, has been gathered from the literature. The most accurate models for predicting the fouling rate are the Polley, Ebert, and Panchal models, with slopes of 0.352, 0.108, and 0.022, respectively, based on fitted curves on the computational fouling rates in terms of comparable experimental values. The sensitivity analysis indicates that the two factors that profoundly affect the fouling rate are the surface temperature and Reynolds number. Using the Polley's equation, the fouling rate in preheat exchangers may be predicted with the highest degree of accuracy, mean sensitivity analysis of 0.29, based on the consistency of calculated and experimental data.

Asphaltene precipitation and deposition in oil reservoirs, wells, transportation, and refineries pose severe problems. Thus, it is important to evaluate its influence by using cutting-edge techniques such as surface treatment. The purpose of the current investigation is to demonstrate how the alteration of casings composition can influence the threshold at which asphaltene can be dislodged from the well column. This can be accompolished by changing surface energy properties. To evaluate the kinetic changes in the removal velocities of asphaltene particles, the intermolecular asphaltene-oil-casing adhesive forces were calculated using the surface energy characteristics of the casings. A study on the experimental size distribution of asphaltene particles was also conducted as a supplement to the theory of surface energy. The mean size of asphaltene particles decreased from 0.6 to 0.4 microns in live oil while the pressure decreased from 5500-4500 psia at 80°C for 260 minutes, before reaching an asumptote. The results showed that particle rebound has a significant impact on the critical velocity of asphaltene removal from the well column which are profoundly influenced by the casing substrate. This can be considered as a viable physical-based surface treatment method to mitigate the deposition of asphaltene in well columns.

Dust storms are increasingly becoming one of the worst and chronic phenomena that endanger human life and the environment. Some of the detrimental impacts, but are not limited to, include inhalation diseases; cancer; and pollution of air and water resources. This, in turn, requires prompt and plausible action. Human activities that intensified the occurrence of dust storms made the present solutions ineffective to contrast with this phenomena, it is imperative to firstly get an in-depth understanding of the phenomenon in terms of mechanisms of dust movement and attachment to various surfaces. The present study endeavors solely to discern the mechanisms of movement and surface deposition and discovers the existing challenges based on previous studies. Then according to the theory of DLVO, the various adhesion forces between dust particles and deposition surfaces are calculated in different situations. The resultant findings of this study reveal that the measurement of determination of such forces is prone to uncertainty to some extent which is discussed in detail. Surface energy and humidity are the most complex factors in dust deposition.