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International audienceThe pulsed column is a widely used technology for liquid-liquid extraction processes in various industries. In this work, the use of this technology has been extended to perform continuous precipitation. An original process of continuous precipitation in emulsion in a pulsed column is thereby developed. A thorough understanding of the behaviour of the dispersed phase inside the column helped to achieve process optimisation and is the purpose of this paper. In this aim, a coupled computational fluid dynamics (CFD)-population balance equation (PBE) approach was developed for the simulation of this original process, and allows the determination of the mean droplet size, which is a key parameter. On one hand, breakup and coalescence kernels for the PBE were selected by performing homogenous type experiments in a stirred tank reactor. The parameters of those kernels were adjusted by fitting the models' parameters to the measured droplets size distribution (DSD) in the stirred tank. One another hand, the continuous phase flow inside the pulsed column was investigated by CFD and has been validated using particle image velocimetry (PIV) data. The latter helped us to choose the best turbulence model representing the flow inside the pulsed column. Finally, the coupled CFD-PBE model was implemented using the quadrature method of moments (QMOM) in the CFD code ANSYS-Fluent (R) to determine the mean droplet size inside the column

In this work, a pressure responsive poly­(α-octadecene-co-maleic acid azobenzene amide) (Azo-MAC) was synthesized and able to enhance the flowability of waxy crude oil with asphaltenes significantly under high pressure. High-pressure UV–vis spectrometer was used to characterize its pressure response under pressures. The onset temperature and enthalpy during wax crystallization of Liaohe waxy crude oil under various pressures were determined by using high-pressure differential scanning calorimeter. The viscosity and yield stress were measured by high-pressure rheometer. On the basis of our experimental data, a mechanism was propounded that the conformation transformation from cis to trans of azobenzene groups in Azo-MAC at enhanced pressure may destroy the assembly of asphaltenes, disturb the crystallization of paraffins and thus improve the flowability of oils. Azo-MAC should be an ideal additive for exploitation and transportation of oils under high pressure.

Catalytic aquathermolysis in situ upgrading and reducing the viscosity of heavy oil in the reservoir remarkably enhances the recovery and is considered as a promising technology. However, the low catalytic efficiency and inferior dispersity in both water and oil limit its applications. In the present work, spherical polymer brush nanocatalysts were synthesized, in which nano-TiO2 is the core and poly­(vinyl imidazole) (PVI)-loading nickel cations are polymer brushes. The chemical characteristics, polymer-grafting content, nickel-loading content, and morphology of as-prepared catalysts were characterized by infrared (IR) spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectrometry, scanning electron microscopy, and transmission electron microscopy. The polymerization degree of PVI was analyzed by proton nuclear magnetic resonance (1H NMR) spectra. The effects of the nickel-loading content, catalytic conditions, and hydrogen donor on the viscosity of heavy oil were studied. The results show that the heavy oil is catalytically cracked by the synthesized catalysts, which leads to the reduction of oil viscosity. The viscosity reduction is enhanced by the increase of the nickel-loading content, catalytic temperature, dosage of catalyst, and hydrogen donor. The rheological behaviors in terms of flow curve, thixotropy, viscoelasticity, and time dependence of cracked oil were studied. To explore the cracking mechanism, the four compositions of heavy oil before and after aquathermolysis were compared. The extracted asphaltenes and resins were further analyzed by elemental analysis, 1H NMR spectra, and IR spectroscopy. The organic compounds in reacted water were characterized by gas chromatography–mass spectrometry. It is found that the content of light saturates is much increased after aquathermolysis, along with the distinct decrease of resins. From the structure change of resins, such as the decrease of hydrogen/carbon and methylene/methyl ratios and increase of aromaticity and aromaticity condensation, the increased light saturates are due to the dissociation of alkyl side chains in resins. In addition, the aromaticity and aromaticity condensation in asphaltenes are found decreased, which is because of the fragmentation and depolymerization of large aromatics. Meanwhile, the loss of oxygen in both asphaltenes and resins is connected with the phenols found in the reacted water, indicating the breakage of the C–O bond and heteroaromatic ring-open reaction in both asphaltenes and resins during aquathermolysis.

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

The kerosene spray generated by a pressure swirl fuel nozzle embedded in a swirling airflow in a swirl cup typical of aeroengine combustors was investigated at different levels of air pressure to assess the counter-acting effects of increasing air density and transfer of centrifugal momentum from airflow to spray. Hardware parameters investigated included air swirl angle and fuel nozzle flow number. Measurement techniques included spray visualization, Phase-Doppler Anemometry (PDA) for spray analysis and Laser-Doppler Anemometry (LDA) for investigation of the air flow field. Operating conditions for PDA measurements were 6, 12, and 18 bar at 700 K. Spray visualizations and LDA measurements were performed at scaled operating conditions. It was found that fuel placement is governed by the presence or absence of a recirculation zone inside the swirl cup and hence by the swirl angle of the airflow. Analysis of temporal aspects of the spray showed the existence of droplet clusters. Configurations characterized by strong swirl furthermore exhibited a preferred frequency of inter-particle times.

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.