Reversal Flow in Fixed-Bed Reactors Operating Under Reaction-Regeneration Cycles

The unsteady state simulation of a set of industrial fixed-bed reactors is presented. The catalytic dehydrogenation of 1-butene into 1-3-butadiene is selected as case study. These reactors operate under reaction-regeneration cycles. Each stage of the process, i.e., dehydrogenation (deactivation by coking), steam purge, oxidative regeneration and evacuation, is simulated by means of the corresponding dynamic model. The kinetic parameters used in the dehydrogenation and regeneration stages for a Cr2O3/Al2O3 catalyst are taken from the literature. The performance of the reactors is investigated for two different operation modes: conventional (CO) and periodic flow reversal (PRFO). The PRFO mode shows significantly lower values for the average bed temperature and residual coke concentrations than those corresponding to the CO mode. This behaviour has a favourable effect on the production rate of butadiene. In addition, the influence of the catalyst sintering is analysed in this paper for both operation modes. The deactivation rate by thermal degradation is lower in the case of PRFO due to the lower average temperature of the catalyst bed. Periodic flow reversal strategies provide an economical and efficient alternative to optimise cyclic processes

Production of biodiesel from acid oil using sulfuric acid as catalyst: Kinetics study

Biodiesel production is becoming more relevant due to its environmental advantages together with the global petroleum situation regarding decreases of the reserves, instability of the prices and so on. The kinetics of the esterification and transesterification reaction of an acid oil (10% of initial free fatty acid) was studied using ethanol and a homogenous acid catalyst. The controlling step method was employed to obtain the kinetic equations, and nonlinear multiparametric routine was implemented to estimate the kinetic parameters. The selected reaction rate represented the experimental data for several operating conditions satisfactorily.Fil: Marchetti, Jorge Mario. Norwegian University of Science and Technology; NoruegaFil: Pedernera, Marisa Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Schbib, Noemi Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Infecciones y trauma ocular

Se describe una serie de infecciones y traumatismos oculares

Simulation of a Silicon CVD Spouted Fluidized Bed Reactor: Semi-Batch Operations

A comprehensive multiphase gas-solid mathematical model that successfully describes the batch growth of silicon particles in a chemical vapor deposition (CVD) submerged spouted bed reactor is extended to simulate semi-batch operations with periodic seeds additions and product extractions. This model takes into account the fluidized bed reactor as well as a population balance equation representing particle growth and agglomeration. Experimental data obtained from semi-batch operation in a pilot scale reactor at REC Silicon Inc. are used to evaluate the proposed mathematical model

Simulation of an Industrial Packed Column for Reactive Absorption of CO2

The steady-state simulation of a reactive absorption column is presented. The absorber is used in a large-scale ammonia plant to remove CO2 from the process gas stream. To enhance the absorption process, high pressures and low temperatures are commonly used (T = 45-80 °C, P = 30-40 bar). At the outlet of the absorber, the CO2 content in the process gas must be reduced to less than 500 ppm (dry basis) to avoid an excessive temperature rise in the methanation reactor (downstream of the absorption section). To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory is considered. The heat effects are taken into account. The behaviour of different process variables for a reference operating condition is analyzed. The influence of changes in some operating variables is evaluated.Fil: Gómez, C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Borio, Daniel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Schbib, Noemi Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Dynamics and control of a radial-flow ammonia synthesis reactor

The steady- and non steady-state simulation of an industrial ammonia converter is presented. The reactor includes two adiabatic radial-flow catalyst beds in series. An interbed (gas-gas) heat exchanger is used to preheat the feed stream. The steady-state results showed good agreement with plant data. The influence of different disturbances (feed composition and temperature, reactor pressure) on the dynamic evolution of the main variables is analysed. The open-loop and closed-loop operation is compared from the standpoint of the reactor stability. © 2001 Elsevier Science Ltd. All rights reserved.Fil: Schbib, Noemi Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Pedernera, Marisa Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Borio, Daniel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin