Nathalie Le Sauze

• Université Toulouse III - Paul Sabatier

Investigations of the settling of liquid droplets in another liquid phase have to deal with the potential contamination of the interfaces with residual impurities. It is shown in this Letter that the use of a centrifugal field to generate the drop settling may overcome this issue: the drop terminal velocity and shape are reached at much shorter tim...

Numerical simulations of a drop crossing a plane liquid-liquid interface in a centrifugal field have been performed by using the Level-Set method. The objective is to characterize the hydrodynamical parameters controlling the coating volume of the droplet, which results from the rupture of the liquid column of lighter phase entrained by the droplet...

Coagulation is a key process particularly in the field of polymer production. Controlling this phenomenon at industrial scale is a significant challenge because it is highly dependent on the operating conditions and the equipment used for the coagulation process. Poor control of coagulation may strongly affect the quality and the reproducibility of...

This study compares the hydrodynamics in three millimeter-scale continuous reactor geometries that can be easily used in laboratories and industries – a straight tube, a coiled tube and a Dean-Hex reactor – via numerical simulations and analyses the data in a way that is specifically relevant to coagulation processes, thereby offering insights for...

Axial dispersion is a key phenomenon in reactor engineering that can affect yield and selectivity when reactions are carried out. Therefore its characterization is necessary for an adequate modelling of the reactor. The development of compact reactors to fit with process intensification expectations requires the use of characterization methods adap...

Aggregation of acrylic latex is investigated inside tubular millireactors working under laminar hydrodynamic conditions. The size distribution and fractal dimension of aggregates are measured using light scattering. Results show that the equilibrium between rupture and aggregation is achieved quickly, allowing the study of cluster size distribution...

A computer simulation of a bubble column is established to determine the residual ozone concentration in the air and the dissolved ozone residual in the water. This study is aimed to improve the control of ozonation systems, both technically and economically. The program is based on mass balances along the contact column, which take into account th...

The aim of this paper is to investigate the influence of physico-chemical parameters on liquid–liquid dispersion at high dispersed phase concentration in Sulzer SMV™ mixer. Four different oil-in-water systems involving two different surfactants are used in order to evaluate the effect of interfacial tension, densities and viscosities ratio on mean...

This paper deals with comparing performances of three different static mixers in terms of pressure drop generated by both single-phase flow and liquid–liquid flow in turbulent flow regime and in terms of emulsification performances. The three motionless mixers compared are the well-known SMX™ and SMV™ and the new version of the SMX called SMXPlus™....

This paper presents an experimental study of pressure drop of single-phase flow and liquid−liquid dispersion through a Sulzer SMX mixer in the turbulent flow regime. Emulsification experiments are performed with various numbers of mixing elements from 2 to 20 and different flow rates ranging from 204 to 600 L/h. Pressure drop in single phase flow w...

Residence time distribution (RTD) experiments are carried out in a pilot plant (QL = 1 m3.h−1). The RTD curves are analyzed by the completely mixed reactors in series model or by the axial dispersion model. Measurements are performed either on the overall bubble column or on four equal parts of the reactor. The bottom part (gas introduction) is com...

A treatment process of gas polluted by hydrogen sulfide or alkyl sulfide is described in this paper. It includes pollutant absorption by an aqueous solution and a continuous regeneration by an ozone oxidation of absorbed compounds. The effects of the main parameters of the process are discussed (pH, concentrations, flow rate,… ). Results are linked...

Emulsions are of great importance to industry. They are involved in many engineering operations, including chemical reactions, extraction, emulsification and suspension polymerization, etc. However, an important problem for these processes is how to control the size distribution of the dispersed phase. Indeed, off-line analysis of the emulsion may...

Liquid phase hydrodynamics in an aerated tank stirred by a down- and an up-pumping pitched blade turbine have been investigated using Particle Image Velocimetry. The effect of agitator configuration and the gas phase on the mean velocity fields and turbulent quantities in the vessel have been investigated. The global mean gas holdup has also been e...

Particle image velocimetry (PIV) and computational fluid dynamics (CFD) have been used to investigate the single phase and gas-liquid flow generated by a Scaba SRGT turbine. The key details of the trailing vortices, the turbulent flow around the impeller blades and the accumulation of gas have been studied by using PIV measurements and CFD simulati...

Axial-flow impellers, like pitched-blade impellers, are being increasingly used for gas−liquid systems in stirred vessels. In this work we have used particle image velocimetry (PIV) and computational fluid dynamics (CFD) models to investigate gas−liquid flow generated by a downflow pitched-blade turbine. PIV measurements were carried out in a fully...

Very numerous and various emulsification processes are currently available. In some rare cases, spontaneous emulsification can occur or require very low amount of energy and induce phase inversion. More often, the quantity of energy involved to produce then break-up droplets to yield a dispersion of sufficient kinetic stability is out of proportion...

In this paper, a new gas–gas mixer, Oxynator, is characterized. The performance of this mixer is compared with two static mixers: Sulzer SMI and Chemineer KMA. In order to study these three gas–gas mixers, first the pressure drop is measured. Secondly, the mixing efficiency is characterized by laser sheet visualizations at the outlet of the mixer....

Trailing vortices behind rotating impeller blades play crucial role in determining gas accumulation behind them. The gas accumulation behind blades affects the pumping and power dissipation capacity of the impeller and thus significantly affects the performance of gas–liquid stirred reactors. Understanding fluid dynamic characteristics of these tra...

Understanding fluid dynamic characteristics of trailing vortices behind impeller blades and the capability to computationally simulate these vortices is essential for reliable design and scale-up of stirred reactors. In this paper, trailing vortices behind the blades of a standard Rushton turbine were studied using particle image velocimetry (PIV)....

Particle Image Velocimetry (PIV) is a technique which enables the instantaneous 2D flow velocity field to be measured. A statistical treatment of a sufficient number of instantaneous flow fields gives the local mean velocity and the root mean square (RMS) velocity of the flow. This technique is now successfully used to study the flow in a stirred t...

Local concentrations are measured at the outlet of different configurations of Sulzer SMV static mixers placed in a tube. Laser Induced Fluorescence is the non intrusive technique used to measure mean and RMS concentrations. The two fluids mixed are miscible and the flow regime is turbulent. The influence of the number of elements, their position a...

The modelling of ozone transfer in water must take into account classical ozonization parameters as well as the type of the fluid flow in the reactor. Even if the disinfection norm proposed in 1987 by the American Agency for the Environmental Protection favours the plug flow reactor, many industrial reactors differ from that ideal reactor. Some of...

The experiments involved the anions SO42-, PO43-, BO33-, SiO22-, NO3-, HCO3-, and CO32- at concentrations identical to those usually found in drinking water. The manipulations were carried out with a simple experimental procedure which allowed one to determine whether the mineral species had an influence on this decomposition and to observe thereof...

L'influence des anions minéraux sur la décomposition de l'ozone est étudiée. Les expériences mettent en oeuvre les anions SO 4 ²⁻ , PO 4 ³⁻ , BO 3 ³⁻ , SiO 2 ²⁻ , NO3-, HCO 3 -+ CO 3 ²⁻ à des concentrations identiques à celles habituellement rencontrées dans le domaine des eaux potables. Un plan d'expérience simple qui permet d'attribuer ou non une...

The modeling of the gas-liquid flow in agitated reactor by the most performing numerical and experimental techniques achieving a tri-dimensional trajectography system was proposed in this paper. Numerous agitators can be utilized in gas-liquid applications. There was chosen the study of Rushton turbine, which represented a model in this research. R...

Axial flow impellers, like pitched blade impellers, are being increasingly used for gas-liquid systems in stirred vessels. In this work we have used particle image velocimetry (PIV) and computational fluid dynamics (CFD) models to investigate gas-liquid flow generated by a down-flow pitched blade turbine. PIV measurements were carried out in a full...

A process to produce continuously microcapsules made of polyurea shell and containing cyclohexane as oil phase is proposed. The polymeric microcapsules are obtained via a two-step process involving emulsification of two immiscible fluids in static mixers followed by interfacial polycondensation in an empty pipe. The use of static mixers in turbulen...