CFD Analysis of Bed Textural Characteristics on TBR Behavior: Kinetics, Scaling-up, Multiscale Analysis and Wall Effects

A simulation of a trickle bed reactor aided by computational fluid dynamics was implemented. With a Eulerian approach, geometrical characteristics were explicitly considered and two simultaneous heterogeneous reactions were included, hydrodesulphurization (HDS) and hydrodenitrogenation (HDN). This was performed in order to achieve the following: (1) attain further insight into a proper scaling‐up procedure to be able to obtain the same hydrodynamics and kinetics behavior in two reactors of different length and diameter scales; (2) develop a multiscale analysis regarding the communication of information between scales through the construction of a porous microstructure model from which the geometrical information of the microscale is captured by the effective transport coefficients (which affect the overall reactor behavior); (3) investigate the effect of operation conditions variations on hydrodynamics and kinetics; (4) and assess the deviations and further differences observed from average to punctual conversion values and the assumptions from kinetic literature models through a preliminary multiscale analysis. The CFD results were validated against experimental pressure drops data as well as HDS and HDN conversions theoretical data. An excellent agreement was found. The model produces a significant improvement in hydrodynamic parameters prediction, achieving 5 times better accuracy in predicting pressure drops and 50% improvement in holdup prediction. The fully coupled model predicts HDS conversion with 96% accuracy and HDN conversion with 94% accuracy. Results suggest that the best way to obtain similar kinetic and hydrodynamic behavior in TBRs with different length and diameter length scales is by equaling the liquid holdup (εγ) or the mass velocities (L‐G)

Estimation of effective diffusion coefficient and its effect on effectiveness factor for hds catalytic process: a multi-scale approach

Effectiveness factors have great relevance in multiphase reactors modeling since they are the conventional way of incorporating the effects of intra-particle resistance reaction rate. This work determines the description level effect of catalytic pellet microstructure on mass and energy effective transport coefficients prediction, isothermal and no isothermal. For such a purpose some results about on evaluation of the effective diffusivity and conductivity with the methodology of volume averaging were applied. The obtained results along with a Langmuir–Hinshelwood/Hougen–Watson kinetic expression were applied to establish the concentration and temperature fields in a catalytic particle. The evaluation of concentration field and effectiveness factors were developed using two different models: pseudohomogeneous mass and energy transport model for a catalytic particle with reaction in all domain, and heterogeneous mass and energy transport model with fluid-catalytic surface interphase reaction for a realistic porous structure model. The results show the differences in concentration and temperature profiles between both models and consequently in effectiveness factors. This could be ascribed to the form of evaluation of effective transport coefficients used in the pseudo-homogeneous model, and presumably to the simple shape of the unit cells used for the solution of the closure problem for the average transport equations with homogeneous reaction

Degradation of 4-Chlorophenol in a Batch Electrochemical Reactor Using BDD Electrodes

The influence of current density (j) (0.25, 0.30, 0.25 and 0.40 A/cm2), initial pH (2.6, 6.5 and 12), stirring speed (As) (400, 500 and 600 rpm), and initial concentration of 4-chlorophenol ([4-CP]0) (300, 500 and 700 mg/L) on degradation of persistent pollutant in a batch electrochemical cell without divisions is presented in this paper. The electrochemical cell was composed of two boron-doped diamond electrodes (BDD). The results of the study showed that best conditions for total degradation of 4-CP were: j of 0.40 A/cm , initial pH of 6.5, As of 500 rpm, and [4-CP]0 of 500 mg/L, after 150 min of reaction time. Removal of total organic carbon (TOC) was 83% at these conditions. The byproducts were identified by UHPLC. This allowed for the proposal of a degradation pathway of 4-CP at the best conditions. Furthermore, these results demonstrate that the electrochemical method employed in this study allows high percentages (96%) of degradation of 4-CP and that the process is applicable to wastewater treatment.CONACYT 26909

Clínica Integrada - ME210 - 202101

Curso de especialidad, de la carrera de medicina, de carácter teórico- práctico del ciclo 7, en el que los estudiantes integran conocimientos previos con la anamnesis, el examen físico y establecen el diagnostico por síndromes o problemas y el plan de trabajo. El curso de Clínica integrada busca desarrollar las competencias generales de comunicación escrita y comunicación oral(nivel 2) y las competencias específicas de práctica clínica-diagnóstico (nivel 2) y profesionalismo-sentido ético y legal y responsabilidad profesional(nivel 2). La integración de conocimientos en la historia clínica, permitirá al estudiante, plantear un adecuado diagnóstico, plan de trabajo para la atención de su futuro paciente