Measurement and Calibration of Droplet Size Distributions in Water-in-Oil Emulsions by Particle Video Microscope and a Focused Beam Reflectance Method

Abstract

Water droplet sizes in crude oil emulsions were measured using an in situ particle video microscope (PVM) probe and a focused beam reflectance measurement (FBRM) probe for a variety of oils spanning over two orders of magnitude in viscosity and for varying shear rates. The arithmetic or Sauter mean diameter was found to maintain the same constants of proportionality with the maximum (99th percentile) droplet size for different distributions, previously only shown for water-continuous emulsions. The FBRM values for the mean droplet size, while lower than the PVM values, could be related to the latter by an empirical quadratic relationship with an average error of less than 20%. The droplet size distribution was found to be represented well by a log-normal distribution with good agreement between correlated and measured mean droplet size. Following the agreement between the mean and maximum droplet sizes, the log-normal standard deviation was linearly related to the mean droplet size. The PVM probe was found to be a useful tool for determining droplet sizes in water-in-oil emulsions and as a calibration method for the FBRM probe. The droplet sizes measured provide a useful set of data for comparison with predictive models to determine the mean size or full droplet size distributions.

Experimental investigation of liquid-liquid system drop size distribution in Taylor-Couette flow and its application in the CFD simulation

“…After performing the simulation for 6 seconds in both cases, final results were obtained. Results are in a good agreement with the experimental data from Boxall et al [7]. This model works if the rotational speed goes from the lower speeds to higher one, since there is no coalescence model then simulation is not able to find the correct drop size distribution if the rotational speed is switched from higher speeds to a lower speed.…”

“…To verify the presented approach we compare our numerical simulations with Roudsari et al [10] and Boxall et al [7], who provide detailed simulations and measurements of droplet size distributions in liquidliquid stirred tank reactor. It has to be noted that their system is water-in-oil; however, it is a good verification system, which we can be used as a case study.…”

“…A specific oil so-called 'Conrone oil' was used as the continuous phase From Boxall et al [7] and water was selected as the dispersed phase. The Conrone oil density, viscosity and interfacial tensions are 842 kg/m 3 , 3.1 cP and 20 mN/m, respectively.…”

“…The Conrone oil density, viscosity and interfacial tensions are 842 kg/m 3 , 3.1 cP and 20 mN/m, respectively. The volume fraction of water is 15% in the Boxall et al [7] paper, however in order to avoid the implementation of a model for the coalescence, a linear correction factor (a function of dispersed phase volume fraction) was applied to the Sauter mean diameter (equation (5)), since the correlation was founded for the dispersed phase which has the volume fraction of 1%. Break up model was written as a user-defined function (UDF) to be implemented in ANSYS FLUENT.…”

“…On one hand, some of these works are just focused on the single drop experiment [2][3][4] to define the break up kernel for the Population balance equation [5] . On the other hand, there are studies focused on the drop size distribution in the stirred tank reactor regardless of the event happens to each droplet [6,7]. The well-defined pattern of the Taylor-Couette flow enables the possibility to investigate DSD as a function of the local fluid dynamic properties, such as shear rate, which is in contrast to more complex devices such as stirred tank reactors.…”