scholarly journals Modeling of adsorber/desorber/catalytic reactor system for ethylene oxide removal

2004 ◽  
Vol 69 (12) ◽  
pp. 1129-1144 ◽  
Author(s):  
Zorana Arsenijevic ◽  
Zeljko Grbavcic ◽  
Bosko Grbic
Keyword(s):  
Ethylene Oxide ◽  
Draft Tube ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Catalytic Reactor ◽  
Combined System ◽  
One Dimensional ◽  
Computational Fluid Dynamics Cfd ◽  
The One ◽  
Oxide Removal

The removal of ethylene oxide (EtO) in a combined system adsorber desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the "hot" section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator while the "cold" section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two sections by use of a draft tube riser. The Computational Fluid Dynamics (CFD) program package FLUENT was used for simulations of the operation of the combined system. In addition, a one-dimensional numerical model for the operation of the packed bed reactor was compared with the corresponding FLUENT calculations. The results of the FLUENT simulations are in very good agreement with the experimental observations, as well as with the results of the one-dimensional numerical simulations.

Reaction-driven instabilities in down-flow packed beds

1995 ◽  
Vol 450 (1938) ◽  
pp. 1-21 ◽  
Keyword(s):  
Hot Spots ◽  
Three Dimensional ◽  
Packed Bed ◽  
Operating Conditions ◽  
Packed Bed Reactor ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
Packed Bed Reactors ◽  
First Order ◽  
The One

Flow maldistributions and corresponding hot spots may cause adverse effects in the operation of down-flow packed-bed reactors. To avoid these phenomena it is necessary to know when and how they occur. In this work, a three-dimensional model that considers the effects of fluid flow, mass transfer by diffusion, heat transfer by conduction and reactant consumption by an exothermic irreversible first-order reaction is used to analyse an adiabatic packed-bed reactor with down-flow. It is shown that the one-dimensional uniform down-flow can become unstable to three-dimensional stationary and time-dependent perturbations, giving rise to non-uniform flow fields that lead to fixed as well as moving hot spots. The boundary of the region of the operating conditions at which these instabilities occur is determined as a function of the various physicochemical parameters that characterize the packed-bed reactor.

scholarly journals CFD tool application in predicting the behavior of a centrifugal fan designed by one-dimensional theory

2021 ◽  
Vol 10 (12) ◽  
pp. e412101219653
Author(s):  
Henrique Marcio Pereira Rosa ◽  
Gabriela Pereira Toledo
Keyword(s):  
Velocity Distribution ◽  
Cfd Simulation ◽  
Centrifugal Fan ◽  
Dimensional Theory ◽  
Recovery Coefficient ◽  
Characteristic Curves ◽  
One Dimensional ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd ◽  
The One

Computational fluid dynamics (CFD) is the most current technology in the fluid flow study. Experimental methods for predicting the turbomachinery performance involve greater time consumption and financial resources compared to the CFD approach. The purpose of this article is to present the analysis of CFD simulation results in a centrifugal fan. The impeller was calculated using the one-dimensional theory and the volute the principle of constant angular momentum. The ANSYS-CFX software was used for the simulation. The turbulence model adopted was the SST. The simulation provided the characteristic curves, the pressure and velocity distribution, and the static and total pressure values at impeller and volute exit. An analysis of the behavior of the pressure plots, and the loss and recovery of pressure in the volute was performed. The results indicated the characteristic curves, the pressure and velocity distribution were consistent with the turbomachinery theory. The pressure values showed the static pressure at volute exit was smaller than impeller exit for some flow rate. It caused the pressure recovery coefficient negative.  This work indicated to be possible design a centrifugal fan applying the one-dimensional theory and optimize it with the CFD tool.

scholarly journals Low concentration volatile organic pollutants removal in combined adsorber-desorber-catalytic reactor system

2008 ◽  
Vol 62 (2) ◽  
pp. 51-58
Author(s):  
Zorana Arsenijevic ◽  
Gordan Savcic ◽  
Dragan Rankovic ◽  
Bosko Grbic ◽  
Nenad Radic ◽  
...  
Keyword(s):  
Energy Consumption ◽  
High Efficiency ◽  
Draft Tube ◽  
Physical Adsorption ◽  
Reactor System ◽  
Catalytic Reactor ◽  
Combined System ◽  
Adsorption And Desorption ◽  
Volatile Organic ◽  
Catalytic Incineration

The removal of volatile organic compounds (VOCs) from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be?nign products, low energy consumption and absence of secondary polluti?on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT) unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.

scholarly journals A packed bed Reactor Combined with Membrane Unit for the Elimination of Toluene Vapours using a Novel Packing Material

2020 ◽  
Vol 9 (1) ◽  
pp. 1679-1683
Keyword(s):  
Membrane Fouling ◽  
Membrane Separation ◽  
Packed Bed ◽  
Polymer Processing ◽  
Packing Material ◽  
Packed Bed Reactor ◽  
Membrane Unit ◽  
Membrane Array ◽  
The One ◽  
Oily Liquid

Toluene is a colorless and aromatic oily liquid primarily used in the petrochemical and polymer processing industries and has been used in this study as the target compound. Continuous experiments were performed in a biofilter on a laboratory scale, followed by a membrane reactor to monitor toluene as one single contaminant. This bioreactor device included a reactor with a packed bed and a membrane array. Pearl millet stacks and berl saddles have been used as packing material for the development of the attached microorganism. Toluene was efficiently treated, with toluene effluent concentrations held at less than 0.4 g m-3 and a Total Removal Efficiency (TRE) of more than 96 % achieved when fluctuating loads were faced by the packed bed reactor. The combined packed bed reactor system had a maximum RE of 93.8 g m -3 h -1 , which was higher than the one obtained with the packed bed reactor alone. In this work the influences on gas membrane separation were also explored in the combined bioreactor and membrane fouling.

Selective Oxidation of Ethylene in an Industrial Packed-Bed Reactor: Modelling, Analysis and Optimization

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Omar Galan ◽  
Vincent G Gomes ◽  
Jose Romagnoli ◽  
Kian F Ngian
Keyword(s):  
Ethylene Oxide ◽  
Catalyst Deactivation ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Coolant Temperature ◽  
Modelling Analysis ◽  
Composition Profiles ◽  
Plant Data ◽  
Personnel Safety ◽  
Optimal Set

This work is focused on the modelling, analysis and optimization of industrial ethylene oxide production in a packed bed reactor. The aim is to identify the critical variables that maximize the reactor productivity in an existing facility without compromising personnel safety and equipment integrity. The chemical reactions involved are highly exothermic making the internal temperature control of this unit a challenging task. Temperature excursions at dangerous levels have been experienced due to variations in composition and temperature of fresh feed to the reactor. Therefore, the prediction of dynamic temperature and composition profiles in the reactor are important for its safe operation. The model we developed incorporates catalyst deactivation and the effect of an inhibitory agent: 1,2-dichloroethene. The model predictions were found to be in good agreement with the plant data. Our model-based optimization studies show that the optimal set point for the inlet coolant temperature is suitable for preventing reactor hot spots and maximizing ethylene oxide selectivity. The heat integration aspects of the process were addressed.

scholarly journals Model Capabilities for In-Situ Oil Shale Recovery

1981 ◽  
Vol 103 (2) ◽  
pp. 138-146 ◽  
Author(s):  
P. J. Hommert ◽  
C. E. Tyner
Keyword(s):  
Oil Shale ◽  
Maximum Yield ◽  
Packed Bed ◽  
The United States ◽  
Packed Bed Reactor ◽  
One Dimensional ◽  
Operating Strategies ◽  
Dimensional Simulation ◽  
Shale Recovery

The extensive oil shale reserves of the United States are now under development as an energy source. One of the approaches for extracting oil from shale is the so-called modified in-situ retort. The operation of such retorts for maximum yield requires an understanding of oil loss mechanisms so that operating strategies that minimize these losses can be developed. The present modeling capabilities for describing the behavior and yield from a modified in-situ retort are discussed. Two models that have been subject to comparison with laboratory retorts are described. The first is a one-dimensional model that treats the retort as a packed bed reactor; the second is a quasi-two-dimensional examination of block retorting. Both models are capable of predicting retorting rates, off-gas composition and oil yield losses to coking and combustion. The major need for modeling now is expansion to multi-dimensional simulation.

scholarly journals Transient one-dimensional model of coal carbonization in a stagnant packed bed

2013 ◽  
Vol 34 (2) ◽  
pp. 39-51 ◽  
Author(s):  
Sylwia Polesek-Karczewska ◽  
Dariusz Kardaś ◽  
Izabela Wardach-Święcicka ◽  
Arkadiusz Grucelski ◽  
Sławomir Stelmach
Keyword(s):  
Flow Characteristics ◽  
Coke Oven ◽  
Packed Bed ◽  
Coal Bed ◽  
Dimensional Model ◽  
One Dimensional ◽  
Measurement Results ◽  
Theoretical Predictions ◽  
Coal Charge ◽  
The One

Abstract In the present paper, the one-dimensional model for heat and mass transfer in fixed coal bed was proposed to describe the thermal and flow characteristics in a coke oven chamber. For the purpose of the studied problem, the analysis was limited to the calculations of temperature field and pyrolytic gas yield. In order to verify the model, its theoretical predictions for temperature distribution during wet coal charge carbonization were compared with the measurement results found in the literature. In general, the investigation shows good qualitative agreement between numerical and experimental data. However, some discrepancy regarding the temperature characteristics at the stage of evaporation was observed.

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