جستجوی مقالات مرتبط با کلیدواژه « Coalescence » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »
تکرار جستجوی کلیدواژه «Coalescence» در نشریات گروه «فنی و مهندسی»-
در این تحقیق، شکست امولسیونهای نفتی با استفاده از اعمال میدان الکتریکی جریان AC در یک سل آزمایشگاهی مورد بررسی قرار گرفت. تاثیر پارامترهای میدان الکتریکی، دما، غلظت سورفکتانت، شوری فاز آب و درصد حجمی آب موجود در امولسیون نفت خام پایدار غرب بر روی بازده جداسازی بررسی شده است. برای این منظور، امولسیون 20% حجمی آب در نفتخام ساخته شد. برای کاهش تاثیر حضور آسفالتن و رزین موجود در نفتخام از محلول 30% وزنی SDS در آب استفاده گردید. نتایج نشان داد با افزایش میدان الکتریکی از صفر تا kV/cm 6، در دمای C 22 بازده جداسازی امولسیون تا 62% و در دمای C 44 تا 86% افزایش پیدا کرد. افزایش دما تا C 53، باعث افزایش بازده جداسازی امولسیون تا حدود 92% تحت میدان kV/cm 6 شد و دما بیشتر از C 53، موجب کاهش بازده جداسازی گردید. افزایش غلظت ماده فعال سطحی از صفر تا 3/2% حجمی در امولسیون تحت میدان kV/cm 6 و دمای C 28، بازده جداسازی را تا 75% افزایش داد و افزایش بیشتر ماده فعال سطحی، باعث کاهش بازدهی شد. افزایش شوری آب در امولسیون نفتخام پایدار غرب موجب کاهش بازده جداسازی گردید. از طرفی، افزایش درصد حجمی آب موجود در امولسیون از 10% تا 30%، بازده جداسازی را از 30% تا 84% افزایش داد.کلید واژگان: شکست امولسیون, جداسازی الکترواستاتیکی, امولسیون آب در نفت, انعقاد, نفت خام}In this study, demulsification of water-in-crude oil emulsions was investigated under various conditions by means of electrostatic dehydrator. The effects of various parameters including temperature, voltage, surfactant concentration, salinity, and water content of the West Paydar crude oil emulsion on the separation efficiency were evaluated. To evaluate the effect of temperature, concentration of surfactant and salinity, emulsions of 20 vol% of water in crude oil were prepared. To overcome the effect of asphaltene and resin of the crude oil in stabilizing the emulsions, SDS was used as a demulsification reagent. Emulsions containing 30 wt% of SDS in water were prepared. By increasing the electrice field from 0 to 6 kV/cm, at 22˚C, efficient separation of West Paydar crude oil emulsions was occurred. The normal separation at ambient temperature was 62% which was increased to 86% at 44˚C. Increasing the temperature up to 53 °C increased the separation of water up to about 92% while applying 6 kV/cm. Increasing the concentration of surfactant from 0 to 2.3 vol% at 6 kV/cm and 28˚C increased the water separation up to 75%. Increase in the water salinity of the West Paydar crude oil emulsion decreased the water separation. Increasing the water content of the emulsion from 10 to 30 vol% increased the water separation from 30 to 84%.Keywords: Demulsification, Electrostatic Separation, Water, in, Crude Oil Emulsion, Coalescence, Crude Oil}
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The coalescence of water droplets in oils may be enhanced by application of an electric field. This approach is commonly used in the crude oil and petroleum industry to separate water from crude oil extracted from oil well. By application of an electric field two patterns of drop-interface coalescence may occur: complete coalescence and partial coalescence. The former is obviously the desirable pattern for industrial coalescers. However in practice, the process of coalescence could actually produce smaller droplets which become more difficult to remove, and hence undesirable. This is caused by either necking, due to extensive elongation of the droplet, or reaction to a fast and energetic coalescence and is referred to as partial coalescence. The volume of the droplets formed in this way has been analyzed as a function of the initial droplet size, electric field strength and change in interface tension between two phases as a result of surface active agents. There is a considerable growth in secondary droplets volume. Expansion speed of the neck connecting the droplet and interface at the beginning of the pumping process has also been quantified and partial coalescence has been explained as a result of competition between pumping and necking processes. These results are useful in optimizing the electro-coalescence process.Keywords: Coalescence, Electric Field, Electro, Coalescer, Interfacial Tension, Pumping Process}
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Bitumen as a binder in coating and insulating materials is modified with polymers to improve its performance in service conditions. Almost all polymers are incompatible with bitumen, and at high temperatures due to relatively very low viscosity of the bitumen phase, are separated from it. These lead to a considerable limitation in the use and handling of polymer-modified bitumens. An understanding of the mechanisms of phase separation of these incompatible mixtures help to improve methods of transportation and handling of polymer-modified bitumens. According to direct observations of the behavior of polyethylene particles in medium of molten bitumen confirm the indirect conclusion already made by others, (coalescence based phase separation) and reject any possibility of occurring Ostwald ripening. This conclusion can also generalized to viscoelastic incompatible polymer blends.Keywords: Polymer, modified bitumen, Phase, separation mechanism, Coalescence, Ostwald ripening, Morphology}
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