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Anand, Vikky
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Anand, Vikky
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Anand, V.
Anand V.
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4 results
Now showing 1 - 4 of 4
- PublicationMitigating Noncoalescence and Chain Formation in an Electrocoalescer by Electric Field Modulation(2022-11-23)
;Hasib, Raunaq; ;Naik, Vijay M. ;Juvekar, Vinay A.Thaokar, Rochish M.In the petroleum industry, dehydration and desalting of a crude oil-brine emulsion are critical to further processing and refining of crude. The process of dehydration and desalting is typically done in large units called electrocoalescers. Enhancing the performance of an electrocoalescer includes the ability to dehydrate the emulsion in a shorter time, that is to increase the rate of separation of water while keeping the operation safe. The work proposes the enhancement of separation based on AC electric field modulation. The modulated waveform is composed of a high amplitude electric field step, followed by a low amplitude electric field step, and the process is repeated. The work demonstrates the efficacy of the technique through several experiments and their analysis. The work includes designing and optimizing the electrical waveform and then demonstrating the faster kinetics of electrocoalescence achieved in comparison with the conventional practice. The main advantage of modulation is facilitation of chaining of drops during the high voltage period, followed by their effective coalescence in the low voltage period. The effect of the modulation field and period has been investigated, and optimization of the time periods of the high field and the low field steps is carried out. Our analysis indicates that an increase in the fraction of the total period spanned by the high field improves the water separation, while a relatively weaker dependence is found on the total period. The electric field was applied both in directions parallel and perpendicular to the gravity, and performances were compared. It was found that the parallel configuration was better than the perpendicular configuration.Scopus© Citations 4 - PublicationDynamics of non-coalescence in unequal sized, conducting multi-droplet system suspended in an insulating medium under an electric field(2022-12-25)
;Roy, Subhankar; Thaokar, Rochish M.An intriguing experimental observation in electrocoalescence of water-in-oil emulsions is the occurrence of a very low critical electric field, beyond which chaining of droplets and shorting of electrodes is observed, as compared with the experimental and theoretical predictions based on two equal sized water droplets in oil. Motivated by these observations, a numerical, analytical and experimental study on the interaction between multiple, unequal sized, perfectly conducting droplets in a perfectly dielectric medium under an electric field is presented here. We show that the critical capillary number , based on the bigger droplet, in a two droplet system, reduces as the radius ratio of the smaller to bigger drop decreases. Secondly, in a system of three equally sized droplets, it is expected that the will be smaller than a two equal sized droplet system, since the electric field experienced by the central droplet is higher when surrounded by two droplets instead of one. Our results show that nonlinearity in the system due to both the asymmetric shape deformation and the electrostatic interaction between the multiple droplets, leads to significant reduction in for onset of non-coalescence in an unequal sized two droplet system or for equal and unequal sized three droplet systems, as compared with for two equal sized droplets. This is possibly one of the underlying mechanisms for observing much smaller in emulsions as compared with a system of two equal sized droplets, and could be responsible for a polydisperse water-in-oil emulsion being exceptionally susceptible to chaining under an electric field.Scopus© Citations 6 - PublicationPlantwide Control of Two Stage Desalting Process for Feed Rate and Grade Disturbances(2022-01-01)
; ;Srivastava, Shashank ;Juvekar, Vinay A. ;Naik, Vijay M. ;Bhartiya, SharadThaokar, Rochish M.The control of crude oil desalting operation in a desalter, especially for the oil-water level control is critical for safe operation. The problem is particularly severe in two-stage desalter, wherein the brine stream from second stage desalter is recycled to first stage desalter. In this work, a dynamic model for the process comprising a kettle and two desalting units is developed. The two control structures are proposed which are differentiated based on the adopted level control strategy. The first control structure is combined with override controllers for increasing the flexibility of process operation with respect to feed rate and grade disturbances. A supervisory layer consisting of two advisory controllers is proposed, which provides the manipulation for manually operated mix valves in the process. - PublicationStability and destabilization of water-in-crude oil emulsion(2021-04-01)
; Thaokar, Rochish M.The crude oil explored from oil wells is in the form of a water-in-oil emulsion. To process the oil for refining into different useful products, the water needs to be separated from the water-in-oil emulsion. There are several procedures reported for breaking the water-in-oil emulsion. Generally, the water present in crude oil is in the form of brine droplets, and the salt concentration may vary from a few hundred to several thousand ppm. The salts present in the crude oil create severe problems in the downstream processing in refineries such as deactivation or poisoning of the catalyst. Therefore, the removal of water from the emulsion is typically the first unit operation in a crude oil refinery. The overall process of separation of water (brine) from crude oil is generally known as desalting. In this chapter, we give a brief discussion on the stability as well as destabilization of the water-in-oil emulsion system. The mechanism of demulsification and the method of breaking water-in-oil emulsion are also discussed in detail.Scopus© Citations 2