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Gas–liquid separators are one type of surface facility among those used in oil fields. In this paper, the study of gas–liquid separation in a cylindrical cyclone separator (GLCC) using computationa...

In our previous articles (Energy & Fuels 2017, 31, 133–139 and Energy & Fuels 2017, 31, 8997–9005), it was presented that the asphaltenes of the Colorado field have different chemical structures, and these change the properties of crystallization of the paraffins. In this paper, we present a new way to understand the effects of the chemical structure of the asphaltenes on crude oil rheology, which includes correlating the average molecular parameters (AMPs) and the concentration of the asphaltenes with rheological properties using chemometric methods such as the partial least squares method. The asphaltenes were separated from six crude oil samples (average °API of 38) and were characterized using nuclear magnetic resonance to determine their main molecular parameters. Rheological properties including viscosity, yield stress, and gel temperature were experimentally determined for each of the crude oil samples and their respective maltenes. The results of a multivariate analysis show that the AMPs of the a...

In a previous article (Molina V., D.; Energy Fuels 2017, 31, 133−139; DOI: 10.1021/acs.energyfuels.6b01887) the structural differences of asphaltenes in Colombian light crude oils from the same field, i.e., the Colorado oilfield, were presented. Colorado crude oil is a light crude with very low content of asphaltenes (

This study embraces the evaluation of the rheological and magneto-rheological properties of heavy and extra-heavy crude oils by applying nanotechnology and magnetism as technological solutions in reducing viscosity. Mixtures of heavy oils with ferrofluids were used to study the viscous effects induced by the action of external magnetic fields. The rheological evaluation covered rotational and oscillatory tests as a function of time and temperature. In the magneto-rheological characterization, there were analyzed the magnetoviscous effects. The results revealed that the crude oils are viscoelastic materials that follow the Generalized Maxwell Model over a wide range of temperatures (-5 to 60 °C). It was also proved that the synergy between the carrier liquid and the nanoparticles promoted a significant reduction of viscosity (~98–99%) and viscoelasticity, which was directly related to the simultaneous action of the solvent and the asphaltene adsorption onto the nanoparticles surface. Critical concentrations of nanoparticles (0.2 wt% and 0.6 wt%) were proved to promote the maximum decrease in viscosity (additional ~ 0.3–0.5% or 1000-3000 cP) and the elastic storage modulus, which was crucial evidence of their effect on hindering the aggregation mechanisms of asphaltenes. In the heavy oil–ferrofluid mixtures, a magneto-rheological effect was demonstrated. The magnetic field attenuated the initial relaxation processes, leading to an increase in the viscosity and shear stress. The phenomenon was attributed to the formation of magnetic chains, such as that observed in magneto-rheological fluids. These results were supported by Scanning Electron Microscopy, which showed the formation of magnetic-field induced thick columnar assemblies of nanoparticles-asphaltene complexes.

The simulation of an industrial boiler in CFD (Computational Fluid Dynamics) is usually done by stages due to the extensive size and the different physical phenomena that occur in different locations of the equipment. In this work, the simulation of an industrial grate boiler is done in three stages, one for the primary air circuit, another one for the secondary air circuit and the final one is the furnace. The combustion of sugarcane bagasse is a complex phenomenon that involves moisture vaporization, devolatilization and char combustion, in order to account for those phenomena, bagasse particles were modeled in a Eulerian-Lagrangian approach. The simulations were performed in commercial software ANSYS FLUENT and the devolatilization model were programmed in C language as a User Defined Function (UDF). When the results of the simulations were compared with experimental data, a satisfactory agreement was observed. Simulations were performed with primary and secondary air inlets modifications in order to optimize the boiler performance, the results of those simulations showed significant improvement in the combustion parameters. La simulación de una caldera industrial en CFD se realiza, usualmente, por etapas debido al gran tamaño y a los diferentes fenómenos físicos que ocurren dentro del equipo. En este trabajo, la simulación de una caldera industrial de parrilla se realiza en tres etapas, la primera es el circuito de aire primario, la segunda es el circuito de aire secundario y la tercera corresponde a la caldera. La combustión de bagazo de caña es un fenómeno complejo que involucra vaporización de la humedad, devolatilización y combustión del carbón, de forma que para evaluar esos fenómenos las partículas de bagazo fueron modeladas en un marco Euleriano-Lagrangiano. Las simulaciones fueron desarrolladas en el software comercial ANSYS FLUENT y la tasa de devolatilización fue programada en lenguaje C como una función definida por el usuario. Cuando los resultados de las simulaciones se compararon con datos experimentales, se observó una concordancia satisfactoria. Se realizaron simulaciones con modificaciones en las entradas de aire primario y secundario buscando optimizar el funcionamiento de la caldera y los resultados de esas simulaciones presentaron una mejoría significativa en los parámetros de combustión.