Drop size distributions in dispersed liquid-liquid pipe flow

Chemical Engineering Research and Design, 2010

The theory of Kolmogorov-Hinze is the base for many studies that have been done on mean drop size and drop size distribution of liquid-liquid dispersions in agitated vessels. Although this theory has been used extensively in the literature, but it does not always give a satisfactory result in the studies and therefore needs to be modified. This paper addresses the effect of phase fraction on drop size distribution in agitated vessels and on the proportionality coefficient and Weber number exponent in the relation d 32 /D ∝ We m. The experimental data that were taken from Pacek et al. (1998) and Desnoyer et al. (2003) have been applied to this relation to investigate the effect of phase ratio. It is shown that even at low phase fractions, the Kolmogorov-Hinze theory necessarily does not give the best result with the −0.6 exponent for the Weber number. Furthermore, for the non-coalescing system, a range of exponent for the Weber number typically from −0.6 to −0.43 can be considered where the system may be approximated as a pseudo-coalescing system at˚= 0.4 in which the obtained results are in good agreement with the results of Pacek et al. (1998).

Two correlations for the prediction of Sauter mean diameter in liquid-liquid dispersion have been proposed in terms of physical properties, batch sedimentation velocity, and hold–up of dispersed phase. These correlations were verified with 127 data points for nine liquid–liquid systems from four different sources and gave the lowest deviation in mean drop sizes compared with other correlations from literature.

AIChE Journal, 1977

Chemical Papers, 2017

Agitating two immiscible liquids or a solid-liquid suspension is an operation frequently performed in the chemical and metallurgical industries, for example, in suspension/emulsion polymerization, heterogeneous/phasetransfer catalytic chemical reactions, and hydrometallurgical solvent extraction. For emulsification, suspension polymerization, solid particle dispersion, and crystallization, it is essential to be able to predict the mean drop/particle size and the drop/particle size distribution. A simple model was proposed for predicting the time evolution of drop size distribution during drop breaking, and was successfully tested on data published by Ruiz and

ISIJ International, 1995

Cold model studies have been carried out to characterize the drop-size distribution in liquid-liquid emulsions formed by bottom gas injection. The emulsion was formed by injecting compressed air through the bottom of a tank containing water and kerosene. A polycondensation technique was used to take samples of the dispersed water drops inside the plume, using a specially designed pneumatic trap. Thedrop samples were photographed and size analysis was done using an image analysis software. The drop-size distribution closely obeyed the Gaudin-Schuhmann equation. Correlations have been developed between the drop size distribution characteristics (the Sauter diameter and standard deviation) and appropriate dimensionless numberscharacterizing the operating conditions. Theexperimental conditions covered the industrial range of these dimensionless numbers. Typical drop diameters were in the range of 0.5 to 8mm.The values of the Sauter diameter were between 4 and 6mm and those for the standard deviation were between 0.8 and I .6 mm.

AIChE Journal, 1980

Experimental measurements of transient drop size distributions in a stirred liquid-liquid dispersion (with low dispersed phase fraction) have been used concomitantly with population balance theory to recover the transition probability of droplet breakage, based on a similarity concept. The data remarkably uphold the proposed similarity hypothesis, and the estimated probability function displays the same qualitative trend as the model due to Narsimhan et al. (1979).

Journal of Petroleum Science and Engineering, 2018

New data on streamwise droplet velocity profiles for low liquid loading pipe flows are reported. The fluids used in the experiments are SF6 (gas-phase) and Exxsol D60 (oil-phase). Experiments are conducted in a 10 cm pipe diameter high-pressure (~780 kPa, absolute) flow loop to reproduce gas-condensate field conditions. Instantaneous streamwise velocity data, obtained using the non-intrusive Laser Doppler Anemometry (LDA) technique, are used to calculate mean and root-mean-squared (RMS) local velocities. Asymmetric droplet velocity profiles with respect to the pipe center-line are observed especially for the stratified low atomization flow conditions. However, as the flow momentum increases, the droplet velocity profiles seem to become more symmetric. Also, these data suggest that, irrespective of the conditions studied, the single-phase gas flow characteristics are preserved closer to the top pipe wall. The data from the LDA imply that the bottom pipe half region is highly influenced by the gas-liquid interfacial characteristics. This results in high streamwise turbulence intensity in the region influenced by the interfacial waves (interfacial turbulence). An isokinetic sampling instrument is also used to measure the local instantaneous dynamic pressure. The dynamic pressure and the locally extracted liquid (droplets) volume rate under isokinetic conditions are used to calculate local fluid velocity. Excellent agreement has been obtained when comparing this calculated local velocity from the isokinetic instrument to the LDA data.

AIChE Journal, 1968

N e w Y o r k Part 1. Prediction of A correlation is presented for predicting Drop Volume the drop volume for injection at low velocities of one Newtonian liquid into a second stationary immiscible Newtonian liquid in the absence

Biotechnology and Bioengineering, 1972

In this work, a radiometric method is used for the determination of the oil drop size distribution in agitated hydrocarbon-water systems. The influence of the counter position, the oil concentration, and the rotation speed of impeller were studied. An experimental parameter is proposed for the definition of the drop size distribution. It was observed that an unsymmetrical distribution represents the drop size distribution better than the normal distribution law.

AIChE Journal, 2007

This work addresses the drop fragmentation process induced by a cross-sectional restriction in a pipe. An experimental device of an upward co-current oil-in-water dispersed flow (viscosity ratio ≈ 0.5) in a vertical column equipped with a concentric orifice has been designed. Drop break-up downstream of the restriction has been studied using a high-speed trajectography. The first objective of this work deals with a global analysis of the fragmentation process for a dilute dispersion. In this context, the operating parameters of the study are the orifice restriction ratio , the flow Reynolds number, Re and the interfacial tension, . The break-up domain has been first mapped on a (Re) graph and drop size distributions have been measured for different flow Reynolds numbers. It was observed that the mean drop diameter downstream of the restriction linearly increases as a function of the inverse of the square root of the pressure drop. This behaviour is in agreement with the observations previously made by Percy and Sleicher [A.I.Ch.E. Journal, 1983, 29(1), 161-164]. In addition, experiments based on the observation of single drop break-up downstream of the orifice have allowed the identification of different breakup mechanisms, and the determination of statistical quantities such as the break-up probability, the mean number of fragments and the daughter drop distribution. The drop break-up probability was found to be a monotonous increasing function of the Weber number based on the maximal pressure drop through the orifice. The mean number of fragments is also an increasing function of the Weber number and the reduced mean daughter drop diameter decreases as the Weber number increases. The daughter drop distributions are multimodal at low and moderate Weber numbers as a result of asymmetrical fragmentation processes. The statistical analysis of single drop break-up experiments was implemented in a simple global population balance model in order to predict the evolution of the size distribution across the restriction at different Reynolds numbers, in the limit of dilute dispersions.