Morphological classification of coke formed from the castilla and jazmín crude oils

Amorphological classification of cokes from the Castilla and Jazmín Colombian crude oils was completed. These heavy-nature crude oils, after being fractioned during the refining stages, were physicochemically characterized and submitted to the coking process. The conclusions of this work are based on the characterization of the feedstock chemical composition according to the type of aromatic carbon. UV visible spectrophotometry and the corresponding micrographs obtained by a Scan Electron Microscope (SEM), in amplification intervals from 100X to 5000X for the samples of formed cokes, were analyzed. Results of this work allowed the determination of the morphological classification intervals in function of the polyaromatic compound concentration ratio (tetraromatic / triaromatic, and diaromatic / triaromatic) of the different coked feedstocks. Furthermore, high content of calcium and sulfur in the feedstocks promotes morphologies of the associated - shot type.Se realizó una clasificación morfológica de los coques obtenidos a partir de los crudos colombianos Castilla y Jazmín. Estos crudos de naturaleza pesada, luego de ser fraccionados en las diferentes etapas de refinación, fueron caracterizados fisicoquímicamente y sometidos al proceso de coquización. Las conclusiones de este trabajo se basan en los resultados de la caracterización de la composición química de la carga por tipo de carbono aromático, empleando espectrofotometría ultravioleta visible y las correspondientes micrografías adquiridas con un Microscopio Electrónico de Barrido (SEM); en un intervalo de ampliación de 100X a 5000X para las muestras de los coques formados. Los resultados de este trabajo permitieron establecer los intervalos de clasificación morfológica, en función de la relación de concentración de poliaromáticos (tetra aromático a tri aromático y di aromático a tri aromático) de las diferentes cargas coquizadas. Además, se pudo determinar que los altos contenidos de calcio y azufre en las cargas promueven morfologías tipo perdigón asociado

Design and evaluation of oxygen transference processes in wastewater treatment

Aprocess of air injection to bodies of water was developed and evaluated. The system is composed of ejectors operated by pressurized water (where atmospheric air is drawn in), a network of contact and distribution pipelines (tubing), and a dispersion system. The influence and importance of each of these parts, especially the ejectors, was studied in order to create a model system that was compared with the most common types of aerators (oxygenators) used in industrial processes for water treatment. The energy efficiency (expressed as kilograms of oxygen transferred per kilowatt/ hour consumed) is used as the unit of comparison of the different processes studied. Furthermore, the comparative advantages of each of the systems were evaluated, namely maintenance, service factor, operation and installation viability, homogeneity, operational stability, adaptability to changing operating conditions among others. It was found that the appropriate industrial installation of an aeration system like the one proposed here, can generate over 30% in energy savings and a 90% reduction in maintenance costs among some of its major advantages.Se desarrolló y evaluó un proceso de inyección de aire a cuerpos de agua, el sistema esta compuestos por eyectores operados por agua a presión (en donde se succiona el aire atmosférico), la red de tubería de contacto y distribución y el sistema de dispersión. La influencia y la importancia de cada una de estas partes, en especial los eyectores, se estudió con el fin de lograr un sistema modelo que fue comparado con los principales tipos de aireadores usados en procesos industriales de tratamiento de agua. Se usó la eficiencia energética, expresada en kilogramos de oxígeno transferido por kilovatio-hora consumido, como unidad de comparación de los diferentes procesos estudiados. También se evaluarón las ventajas comparativas de cada uno de los sistemas como mantenibilidad, factor de servicio, facilidad de operación, facilidad de instalación, homogeneidad, estabilidad operacional, adaptabilidad a cambios de condiciones de operación entre otras. Se encontró que la adecuada instalación industrial de un sistema de aireación como el propuesto puede generar ahorros de energía de más del 30% y reducción de costos de mantenimiento del 90% entre sus principales ventajas

Kinetic analysis of the termal decomposition of colombian vacuum residua by termogravimetry

Five different Colombian vacuum residues were thermally decomposed in a thermogravimetric analyzer. Three heating rates were employed to heat the sample up to 650°C. The kinetic analysis was performed by the Coats-Redfern method to describe the non-isothermal pyrolysis of the residua, a reaction model where the reaction order gradually increases from first to second order is proposed and an excellent agreement of the experimental with the calculated data is presented. The results also indicate that the pyrolysis of a vacuum residue cannot be modeled by a single reaction mechanism

Cfd simulation of a pilot plant delayed coking reactor using an in-house cfd code

ABSTRACT A simulation of a pilot plant delayed coking reactor was performed using an in-house computational fluid dynamics (CFD) code. The reactor was modeled as a three-phase dynamic system where the coke is the porous solid phase, the vacuum residue the liquid phase and the distillable product the gas phase. Equations of continuity, momentum, and energy proposed to describe the coking dynamic process where discretized employing the finite volume method and the domain was defined by a 2D structured axisymmetric grid. A PEA algorithm was developed to account for the drag between the fluid phases, and a modified SIMPLEC algorithm achieved the pressure-velocity coupling. The CFD simulator was programmed in C++ code for Linux operating system; all the graphics were constructed in ParaView visualization platform. A full run of 12 hours and the cooling of the resulting coke bed for three different vacuum residues were simulated, the results were compared with experimental data and a good agreement was observed, the simulator demonstrated great potential to be scaled up to industrial level.RESUMO Foi realizada uma simulação de uma planta piloto de um reator de coqueamento retardado aplicando um código interno de fluidodinâmica computacional (CFD). O reator foi modelado como um sistema dinâmico de três fases, estando o coque em fase sólida, o resíduo de vácuo em fase líquida, e os destiláveis em fase gasosa. As equações de continuidade, de momento e de energia propostas para descrever o processo de coquemento dinâmico foram discretizadas utilizando o método dos volumes finitos, e a área foi definida por uma grade de eixo de simetria estruturada em 2D. Foi desenvolvido um algoritmo PEA para representar o arrasto entre as fases fluidas, e um algoritmo SIMPLEC modificado atingiu o acoplamento pressão-velocidade. O simulador CFD foi programado em código C++ para o sistema operacional Linux. Todos os gráficos foram construídos em uma plataforma ParaView. Simulando a operação de 12 horas e o arrefecimento do leito de coque resultante para três resíduos de vácuo diferentes, os resultados foram comparados com os dados experimentais e foi observado uma boa correlação, o simulador mostrou grande potencial de ser escalado no nível industrial.RESUMEN Una simulación de un reactor piloto de coquización retardada fue realizada empleando un código propio de dinámica de fluidos computacional (CFD). El reactor fue modelado como un sistema dinámico de tres fases donde el coque es una fase sólida porosa, el fondo de vacío es la fase líquida y los productos destilables son la fase gaseosa. Los balances de continuidad, momento y energía propuestos para describir la dinámica del proceso de coquización fueron discretizados mediante el método de los volúmenes finitos sobre una malla axisimétrica de dos dimensiones. Un algoritmo tipo PEA fue desarrollado para describir el arrastre entre las fases fluidas y un algoritmo SIMPLEC modificado llevó a cabo el acoplamiento entre la presión y la velocidad. El simulador de CFD fue programado en lenguaje C++ para sistema operativo tipo Linux; todos los gráficos fueron construidos en la plataforma de visualización Paraview. Una corrida completa de 12 horas y el posterior enfriamiento de la cama de coque obtenida para tres fondos de vacío fue simulada, los resultados fueron comparados con datos experimentales y un buen acuerdo fue encontrado, el simulador demostró gran potencial para ser escalado a nivel industrial

Kinetic analysis of the termal decomposition of colombian vacuum residua by termogravimetry

Five different Colombian vacuum residues were thermally decomposed in a thermogravimetric analyzer. Three heating rates were employed to heat the sample up to 650°C. The kinetic analysis was performed by the Coats-Redfern method to describe the non-isothermal pyrolysis of the residua, a reaction model where the reaction order gradually increases from first to second order is proposed and an excellent agreement of the experimental with the calculated data is presented. The results also indicate that the pyrolysis of a vacuum residue cannot be modeled by a single reaction mechanism.Cinco fondos de vacío colombianos fueron procesados mediante descomposición  térmica en una balanza termogravimétrica. Tres tasas de calentamiento fueron empleadas para calentar la muestra hasta una temperatura de 650 °C. El análisis cinético fue realizado mediante el método de Coats-Redfern para describir la pirólisis no isotérmica del residuo, se propuso un modelo de reacción donde el orden de la reacción aumenta gradualmente de primer a segundo orden y se encontró un  excelente ajuste de los datos calculados con los datos experimentales. Los resultados también indican que la pirólisis de un fondo de vacío no puede ser modelada por un solo mecanismo de reacción

Design and rationale of the XIENCE short DAPT clinical program: An assessment of the safety of 3-month and 1-month DAPT in patients at high bleeding risk undergoing PCI with an everolimus-eluting stent

Dual antiplatelet therapy (DAPT) is key for the prevention of recurrent ischemic events after percutaneous coronary intervention (PCI); however, it increases the risk of bleeding complications. While new generation drug-eluting stents have been shown superior to bare-metal stents after a short DAPT course, the optimal DAPT duration in patients at high bleeding risk (HBR) remains to be determined. TRIAL DESIGN: The XIENCE Short DAPT program consists of three prospective, single-arm studies (XIENCE 90, XIENCE 28 Global and XIENCE 28 USA) investigating 3- or 1-month DAPT durations in HBR patients undergoing PCI with the XIENCE stent. The XIENCE 90 study is being conducted in the US and enrolled 2047 subjects who discontinued DAPT at 3 months if they were free from myocardial infarction (MI), repeat coronary revascularization, stroke, or stent thrombosis. The XIENCE 28 program includes the USA study, enrolling 642 patients in US and Canada, and the Global study, enrolling 963 patients in Europe and Asia. In XIENCE 28, patients were to discontinue DAPT at 1 month post-PCI if event-free. The primary hypothesis for both XIENCE 90 and XIENCE 28 is that a short DAPT regimen will be non-inferior to a conventional DAPT duration with respect to the composite of all-cause death or MI. Patients enrolled in the prospective multicenter post-market XIENCE V USA study will be used as historical control group in a stratified propensity-adjusted analysis. CONCLUSIONS: The XIENCE Short DAPT Program will provide insights into the safety and efficacy of 2 abbreviated DAPT regimens of 3- and 1-month duration in a large cohort of HBR patients undergoing PCI with the XIENCE stent

3- or 1-Month DAPT in Patients at High Bleeding Risk Undergoing Everolimus-Eluting Stent Implantation.

OBJECTIVES The aim of this study was to evaluate 2 abbreviated dual-antiplatelet therapy (DAPT) regimens in patients at high bleeding risk (HBR) undergoing percutaneous coronary intervention (PCI). BACKGROUND Current-generation drug-eluting stents are preferred over bare-metal stents for HBR patients, but their optimal DAPT management remains unknown. METHODS The XIENCE Short DAPT program included 3 prospective, multicenter, single-arm studies enrolling HBR patients who underwent successful PCI with a cobalt-chromium everolimus-eluting stent. After 1 month (XIENCE 28 USA and XIENCE 28 Global) or 3 months (XIENCE 90) of DAPT, event-free patients discontinued the P2Y12 inhibitor. The postmarketing approval XIENCE V USA study was used as historical control in a propensity score-stratified analysis. RESULTS A total of 3,652 patients were enrolled. The propensity-adjusted rate of the primary endpoint of all-cause mortality or myocardial infarction was 5.4% among 1,693 patients on 3-month DAPT versus 5.4% in the 12-month DAPT historical control (Pnoninferiority = 0.0063) and 3.5% among 1,392 patients on 1-month DAPT versus 4.3% in the 6-month DAPT historical control (Pnoninferiority = 0.0005). Bleeding Academic Research Consortium (BARC) types 2 to 5 bleeding was not significantly lower with 3- or 1-month DAPT, while BARC types 3 to 5 bleeding was reduced in both experimental groups. The rate of definite or probable stent thrombosis was 0.2% in XIENCE 90 (P < 0.0001 for the performance goal of 1.2%) and 0.3% in XIENCE 28. CONCLUSIONS Among HBR patients undergoing PCI with cobalt-chromium everolimus-eluting stents, DAPT for 1 or 3 months was noninferior to 6 or 12 months of DAPT for ischemic outcomes and may be associated with less major bleeding and a low incidence of stent thrombosis