Experimental Study of Bubble-Droplet Interactions in Improved Primary Oil Separation

2019 ◽  
Author(s):  
Joel R. Karp ◽  
Ernesto Mancilla ◽  
Paulo H. D. Santos ◽  
Moisés A. Marcelino Neto ◽  
Rigoberto E. M. Morales
Keyword(s):  
Contact Angle ◽  
Tap Water ◽  
Bubble Radius ◽  
Gas Bubbles ◽  
Terminal Velocity ◽  
Continuous Phase ◽  
Major Influence ◽  
Oil Droplets ◽  
Pure Nitrogen ◽  
Dispersed Phases

Abstract The interactions between dispersed oil droplets and gas bubbles was experimentally studied in this work. An experimental set-up was built in the Multiphase Flow Research Center (NUEM) in the Federal University of Technology – Paraná (UTFPR) to conduct a fundamental evaluation of the interactions between sessile gas bubbles and oil droplets employing side-view flow visualization. Tap water was used as the continuous phase, whereas pure nitrogen and colored vegetable oil were employed as the dispersed phases. The bubble-droplet attachment consisted in the encapsulation of the bubble by the droplet, presenting phenomenological similarities to droplet-droplet coalescence. The contact between the dispersed phases induces the formation of a connecting bridge, which grows rapidly with time, with the height of the bridge being comparable to the size of the droplet after 57.0 ms. The inherent asymmetry of the phenomenon induced a significant horizontal displacement of the bubble towards the droplet, whose position remained unaltered. The evaluation of the bridge meniscus corroborated to this observation, since the contact angle on the droplet side decayed faster with time in comparison to the contact angle on the bubble side. The hydrodynamics of the rising aggregate is also evaluated, by the obtainment of its size, three-dimensional trajectory and terminal velocity. The stable aggregates formed presented an increase factor of 150 to 180%, based on the terminal velocity of the individual droplet. The radius of the bubble was found to be the major influence on the hydrodynamics of the aggregate, allowing the definition of a critical bubble radius based on trajectory instabilities.

Measurements of the Terminal Velocity of Bubbles Rising in a Chain

1973 ◽  
Vol 95 (1) ◽  
pp. 17-22 ◽  
Author(s):  
C. H. Marks
Keyword(s):  
Bubble Size ◽  
Tap Water ◽  
Bubble Radius ◽  
Terminal Velocity ◽  
Bubble Velocity ◽  
Distilled Water ◽  
Rise Velocity ◽  
Sugar Water ◽  
A Chain ◽  
Made In

Measurements were made of the effect of frequency of formation on the velocity of air bubbles rising in a chain through distilled water, lap water, and sugar water. In all cases, increasing the frequency increased the rise velocity for a given bubble size. Measurements made in distilled water showed that the increase of velocity with frequency dropped off with bubble size until it was negligible for the smaller bubbles. It was shown that the variation of bubble velocity with frequency and size can be fairly well correlated with the velocity of rise of solitary bubbles by means of a model based on turbulent wake theory. Tap-water measurements showed the same effect of impurities in the water on the bubble rise velocity as had been observed for solitary bubbles; however, the bubble radius at which the effect became apparent decreased with frequency. Measurements made in sugar water showed that the effect of fluid properties on the rise velocity decreased as frequency increased. At the highest frequencies, no difference could be seen between the distilled water and the sugar water rise velocity curves.

Numerical Simulation of Droplet Generation in Series Co-Flow Capillaries

2009 ◽  
Author(s):  
Yanxi Song ◽  
Jinliang Xu
Keyword(s):  
Reynolds Number ◽  
Disperse Phase ◽  
Weber Number ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Disperse Flow ◽  
Double Emulsions ◽  
Wide Range ◽  
In Series ◽  
Dispersed Phases

We study the production and motion of monodisperse double emulsions in microfluidics comprising series co-flow capillaries. Both two and three dimensional simulations are performed. Flow was determined by dimensionless parameters, i.e., Reynolds number and Weber number of continuous and dispersed phases. The co-flow generated droplets are sensitive to the Reynolds number and Weber number of the continuous phase, but insensitive to those of the disperse phase. Because the inner and outer drops are generate by separate co-flow processes, sizes of both inner and outer drops can be controlled by adjusting Re and We for the continuous phase. Meanwhile, the disperse phase has little effect on drop size, thus a desirable generation frequency of inner drop can be reached by merely adjusting flow rate of the inner fluid, leading to desirable number of inner drops encapsulated by the outer drop. Thus highly monodisperse double emulsions are obtained. It was found that only in dripping mode can droplet be of high mono-dispersity. Flow begins to transit from dripping regime to jetting regime when the Re number is decreased or Weber number is increased. To ensure that all the droplets are produced over a wide range of running parameters, tiny tapered tip outlet for the disperse flow should be applied. Smaller the tapered tip, wider range for Re and we can apply.

Behavior of Inert Gas Bubbles in Forced Convective Liquid Metal Circuits

1976 ◽  
Vol 98 (1) ◽  
pp. 5-11 ◽  
Author(s):  
W. J. Minkowycz ◽  
D. M. France ◽  
R. M. Singer
Keyword(s):  
Liquid Metal ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Liquid Sodium ◽  
Gas Bubble ◽  
Flowing Liquid ◽  
Argon Gas ◽  
The Core

Conservation equations are derived for the motion of a small inert gas bubble in a large flowing liquid-gas solution subjected to large thermal gradients. Terms which are of the second order of magnitude under less severe and steady-state conditions are retained, thus resulting in an expanded form of the Rayleigh equation. The bubble dynamics is a function of opposing mechanisms tending to increase or decrease bubble volume while being transported with the solution. Diffusion of inert gas between the bubble and the solution is one of the most important of these mechanisms included in the analysis. The analytical model is applied to an argon gas bubble flowing in a weak solution of argon gas in liquid sodium. Calculations are performed for these fluids under conditions typical of normal and abnormal operation of a liquid metal fast breeder reactor (LMFBR) core and the resulting bubble radius, internal gas pressure, and mass of inert gas are presented in each case. An important result obtained indicates that inert gas bubbles reaching the core inlet of an LMFBR will always grow as they traverse the core under normal and extreme abnormal conditions and that the rate of growth is quite small in all cases.

Experimental Evaluation of Control Fluid Fallback During Off-Bottom Well Control

2002 ◽  
Author(s):  
Fernando S. Flores-Avila ◽  
John Rogers Smith ◽  
Adam T. Bourgoyne ◽  
Darryl A. Bourgoyne
Keyword(s):  
Liquid Flow ◽  
Liquid Droplet ◽  
Drilling Fluid ◽  
Terminal Velocity ◽  
Continuous Phase ◽  
Flow Conditions ◽  
Fluid Accumulation ◽  
Well Control ◽  
Water Based ◽  
Control Fluid

This study measured the liquid fallback during simulated blowout conditions. The purpose of the study was to establish a basis for developing a procedure for controlling blowouts that relies on the accumulation of liquid kill fluid injected while the well continues to flow. The results from full-scale experiments performed with natural gas and water based drilling fluid in a vertical 2787-foot deep research well are presented. The results show that the critical velocity that prevents control fluid accumulation can be predicted by adapting Turner’s model of terminal velocity based on the liquid droplet theory to consider the flow conditions, velocity and properties of the continuous phase when determining the drag coefficient. Similarly, the amount of liquid that flows countercurrent into and accumulates in the well can be predicted based on the concept of zero net liquid flow (ZNLF) holdup.

scholarly journals Electron Microscopy of Bubbles and Dislocations in Helium Implanted Metals

2021 ◽  
Author(s):  
◽  
Kevin John Stevens
Keyword(s):  
Electron Diffraction ◽  
Bubble Radius ◽  
Gas Bubbles ◽  
Foil Thickness ◽  
Dislocation Loops ◽  
Displacement Fields ◽  
Imaging Parameters ◽  
Transmission Electron ◽  
Wide Range ◽  
Isotropic Elasticity

<p>The theoretical contrast in transmission electron microscope of a superlattice of helium gas bubbles in copper is computed using the two-beam and many-beam dynamical theories of electron diffraction with the aim the aim of measuring the density and size of dislocation loops associated with the bubble array. A wide range of parameters (foil thickness, diffraction vector, excitation error, defocus, and depth, radius, and strain-field of the bubble) is considered to considered to construct a library of theoretical images and intensity profiles for a single, isolated bubble. Various criteria are applied to obtain a measurement of the bubble radius from the simulations but the results are inaccurate because of the sensitive dependence of the intensity profile on the imaging parameters. A better measurement is profiles from a single stack of bubbles are modeled and electron diffraction from superlattices simulated. The results obtained suggest that the bubble ordering is of limited extent. A library is made of the theoretical contrast when imaging a system of dislocation loops punched out along the <110> directions by the growth of gas bubbles ordered on a superlattice aligned with the host fcc matrix. These image simulations use the displacement fields surrounding loops and bubbles predicted by isotropic elasticity theory. For a variety of structures involving loops and bubbles, the following imaging parameters were investigated: beam direction, foil normal, diffracting vector, excitation error, number of beams, and defocus, These simulations indicate that it should be possible to image the small dislocations at high density thought to be present in the bubble lattice, provided well focused micrographs taken under strong two-beam conditions can be obtained. In Practice it proved difficult to tilt specimens containing superlattices to strong two-beam conditions because of the deterioration in crystallinity resulting from the implantation. However, the lower concentrations by low dose implantations.</p>

scholarly journals Impact of the Hydrophobicity of the Particles on the Formation and Behavior of Oil Particle Aggregates (OPA)

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Wen Ji ◽  
Lin Zhao ◽  
Kenneth Lee ◽  
Thomas King ◽  
Brian Robinson ◽  
...  
Keyword(s):  
Contact Angle ◽  
Crude Oil ◽  
Marine Environment ◽  
Bottom Layer ◽  
Trapping Efficiency ◽  
Oil Droplets ◽  
Particle Aggregates ◽  
And Behavior

ABSTRACT Oil droplets in marine environment interact with particles to form oil particle aggregates (OPA). As it was argued that the hydrophobicity of particles impacts the formation of OPA and subsequently the entrapment of oil and the transport of OPA, this study altered the hydrophobicity of kaolinite through the addition of chitosan and the contact angle was increased from 28.8° to 57.3°. Modified kaolinite was mixed with 500 mg/L crude oil in 200 rpm for 3 hours, then bottom layer was separated and extracted. Observations of the settled OPA microscale structure and calculations of oil trapping efficiency (OTE) were accomplished. Results indicated that with higher hydrophobicity of kaolinite, oil droplets were maintained in larger sizes in OPAs. This could increase the buoyancy of formed OPAs, thus decrease the amount of settled OPAs.

Zero Dimensional Model for the Growth of Heterogeneous Gas Bubbles

2006 ◽  
Author(s):  
Hatem M. Wasfy ◽  
Tamer M. Wasfy
Keyword(s):  
Contact Angle ◽  
Bubble Growth ◽  
Growth Stage ◽  
Bubble Radius ◽  
Wait Time ◽  
Contact Radius ◽  
Ambient Conditions ◽  
Spherical Cap ◽  
Second Stage ◽  
The Third

A zero dimensional energy based model for heterogeneous gas bubble growth from conical surface pits is presented. The spherical cap bubble growth is divided into 3 stages. In the first stage, the bubble is within the surface pit. In the second stage, the bubble is anchored to the circular opening of the surface cavity and the apparent bubble contact angle decreases while the bubble's contact radius remains the same. The third growth stage starts when the apparent contact angle becomes the same as the contact angle under the ambient conditions. In the third growth stage, the contact radius increases while the contact angle remains constant. The predicted bubble radius versus time since the detachment of the previous bubble was found to be in good agreement with published experimental data for CO2 bubbles growing in water. The long wait time observed in the experiments before a measurable bubble appears after the detachment of the previous bubble was also calculated.

scholarly journals Drop formation in microfluidic cross-junction: jetting to dripping to jetting transition

2019 ◽  
Vol 23 (8) ◽  
Author(s):  
Nina M. Kovalchuk ◽  
Masanobu Sagisaka ◽  
Kasparas Steponavicius ◽  
Daniele Vigolo ◽  
Mark J. H. Simmons
Keyword(s):  
Interfacial Tension ◽  
Capillary Number ◽  
Continuous Phase ◽  
Flow Rate Ratio ◽  
Dispersed Phase ◽  
Flow Focusing ◽  
Jet Formation ◽  
Relative Contribution ◽  
Power Law Function ◽  
Dispersed Phases

AbstractThe regimes of drop generation were studied in a Dolomite microfluidic device which combined both hydrodynamic and geometrical flow focusing over a broad range of flow rates. A series of aqueous dispersed phases were used with a viscosity ratio between continuous and dispersed phases of close to unity. Surfactants were added to alter the interfacial tension. It was shown that the transition from dripping to jetting is well described by the capillary numbers of both the dispersed and continuous phases. Only the jetting regime was observed if the capillary number of the dispersed phase was above a critical value, whereas at smaller values of this parameter a jetting → dripping → jetting transition was observed by increasing the capillary number of the continuous phase. The analysis performed has shown that the conditions for a dripping to jetting transition at moderate and large values of the capillary number of the continuous phase can be predicted theoretically by comparison of the characteristic time scales for drop pinch-off and jet growth, whereas the transition at small values cannot. It is suggested that this transition is geometry mediated and is a result of the interplay of jet confinement in the focusing part and a decrease of confinement following entry into the main channel. The flow fields inside the jet of the dispersed phase were qualitatively different for small and large values of the capillary number of the continuous phase revealing the relative contribution of the dispersed phase flow in jet formation. The volume of the drops formed in the jetting regime increased as a power law function of the flow rate ratio of the dispersed to continuous phase, independent of the interfacial tension.

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