scholarly journals System Approach from Biomass Combustion in Packed Bed Reactor

2007 ◽  
Vol 7 (1 & 2) ◽  
pp. 16 ◽  
Author(s):  
Anhkien Le ◽  
Le Xuan Hai ◽  
V. N. Sharifi ◽  
J. Swithenbank
Keyword(s):  
Steady State ◽  
Transition Period ◽  
Computing Time ◽  
Substrate Inhibition ◽  
Simple Algorithm ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Biomass Combustion ◽  
Stable Steady State ◽  
State Tests

A simple algorithm originally proposed by Choong, Paterson and Scott (2002) was tested on a model of an isothermal controlled-cycled stirred tank reactor with substrate inhibition kinetics, (r = 1 ~c). In previous work, this reacting system had been shown to exhibit steady-state multiplicity. The transition period of this system to the stable steady state is sometimes characterized by very slow change followed by a very rapid convergence to the stable steady state. Tests of the Choong-Paterson-Scott algorithm showed that the feature, which prevents premature termination of the calculations prior to reaching the true steady state, is very useful for this system. However, tests of the stopping criterion showed that the other feature of reducing the computing time was not realized in this system.

scholarly journals Use of a Novel Algorithm to Determine Cyclic Steady State

2006 ◽  
Vol 6 (2) ◽  
pp. 70 ◽  
Author(s):  
Luis E Razon
Keyword(s):  
Steady State ◽  
Transition Period ◽  
Computing Time ◽  
Substrate Inhibition ◽  
Simple Algorithm ◽  
Stable Steady State ◽  
Stopping Criterion ◽  
State Tests ◽  
Substrate Inhibition Kinetics ◽  
State Multiplicity

A simple algorithm originally proposed by Choong, Paterson and Scott (2002) was tested on a model of an isothermal controlled-cycled stirred tank reactor with substrate inhibition kinetics, (r = 1 ~c). In previous work, this reacting system had been shown to exhibit steady-state multiplicity. The transition period of this system to the stable steady state is sometimes characterized by very slow change followed by a very rapid convergence to the stable steady state. Tests of the Choong-Paterson-Scott algorithm showed that the feature, which prevents premature termination of the calculations prior to reaching the true steady state, is very useful for this system. However, tests of the stopping criterion showed that the other feature of reducing the computing time was not realized in this system.

Steady State Model for Heat Transfer in a Packed Bed Reactor of Elliptic Cylindrical Shape

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Laércio G. Oliveira ◽  
Ramdayal Swarnakar ◽  
Antonio G. B. de Lima
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Fixed Bed ◽  
Packed Bed ◽  
Numerical Results ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Dimensionless Temperature ◽  
Cylindrical Shape ◽  
Temperature Profiles

The fixed-bed reactors of circular cylindrical geometry with heated or cooled walls are frequently used to carry out heterogeneous reactions of solid-gas type in engineering applications. The design of a fixed bed reactor requires an extensive knowledge of heat transfer characteristics within the packed bed. In this sense, this work presents a three-dimensional mathematical model to predict the heat transfer inside a fixed bed elliptical cylinder heat exchanger. The model considers uniform velocity and temperature profiles of the fluid phase at the entrance of the reactor, and constant thermo-physical properties. The surface of the equipment convective boundary condition is assumed to be constant. The energy equation, written in the elliptical cylindrical coordinates, was discretized using a finite-volume method considering a fully implicit formulation, and WUDS interpolation scheme. Numerical results of the dimensionless temperature profiles inside the packed bed reactor at a steady state are presented and temperature distribution is interpreted. To validate the model, numerical results obtained for the circular cylinder are compared with analytical results from literature and a good agreement was obtained.

Effect of Concentration by Thermal Swing Adsorption on the Catalytic Incineration of VOCs

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Agustina Campesi ◽  
Carlos D. Luzi ◽  
Osvaldo M. Martínez ◽  
Guillermo Barreto
Keyword(s):  
Computing Time ◽  
Numerical Procedure ◽  
Mass Conservation ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Thermal Swing Adsorption ◽  
Order Of Magnitude ◽  
Intraparticle Mass Transfer ◽  
Air Streams ◽  
Lower Flow Rate

Abstract Among the different processes for elimination of volatile organic compounds (VOCs) from gaseous effluents (mainly air streams), the frequently employed catalytic oxidation is undertaken in this contribution. With the purpose of reducing the amount of catalyst needed for incineration and the surface of recuperative heat exchangers, thermal swing adsorption can be use as a previous step for VOC concentration.By means of simulating the behavior of a conventional packed bed reactor and using kinetic expressions recently developed for the incineration of mixtures of ethyl acetate and ethanol on a laboratory catalyst based on Mn/Cu oxides, it is shown in this paper that the reduction in catalyst volume is significantly larger than the concentration factor, due to the combined effect of the lower flow rate and temperature rise.A second aspect dealt with in this contribution concern the simulation of the packed bed reactor. The intraparticle mass-transfer limitations turn out to be very strong and, consequently, the mass conservation balances of three species inside the particles should be solved numerically and iteratively at each position inside the bed. A precise approximation to circumvent such procedure is developed and shown to reduce computing time in more than one order of magnitude and to avoid convergence troubles otherwise found with the numerical procedure.

scholarly journals Recovery of UAPB from high organic load during startup for phenolic wastewater treatment

2011 ◽  
Vol 17 (4) ◽  
pp. 517-524 ◽  
Author(s):  
Zeinab Bakhshi ◽  
Ghasem Najafpour ◽  
Neya Navayi ◽  
Esmaeel Kariminezhad ◽  
Roya Pishgar ◽  
...  
Keyword(s):  
Steady State ◽  
Removal Efficiency ◽  
Biogas Production ◽  
Phase 1 ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Phenol Concentration ◽  
Synthetic Wastewater ◽  
Organic Load ◽  
Phenol Removal

Biodegradation of synthetic wastewater containing phenol by upflow anaerobic packed bed reactor (UAPB) was studied in this work. The reactor was operated at a hydraulic retention time (HRT) of 24 h and under mesophilic (30?1?C) conditions. The startup operation was conducted for 150 days; split into 4 phases. The phenol concentration was stepwise increased. The concentration of phenol in phases 1, 2, 3 and 4 were 100, 400, 700 and 1000 mg/l, respectively. In phase 1, the reactor reached steady state conditions on the 8th day with a phenol removal efficiency and biogas production rate of 96.8% and 1.42 l/d, respectively. For an increase of the initial phenol concentration in phase 2, a slight decrease in phenol removal efficiency was observed. Similar trends were observed in phases 3 and 4 of startup. Due to the high phenol concentration a sudden decrease in removal efficiency and biogas production was observed. The surviving microorganisms were gradually adapted and acclimated to high phenol concentrations. In phases 3 and 4, the phenol removal efficiency at steady state conditions were 98.4 and 98%, respectively. The maximum biogas production was observed at day 130 with a value of 3.57 l/d that corresponds to phenol concentration of 1000 mg/l.

scholarly journals Steady-state inhibition model for the biodegradation of sulfonated amines in a packed bed reactor

2015 ◽  
Vol 32 (3) ◽  
pp. 379-386 ◽  
Author(s):  
Cleotilde Juárez-Ramírez ◽  
Juvencio Galíndez-Mayer ◽  
Nora Ruiz-Ordaz ◽  
Oswaldo Ramos-Monroy ◽  
Fortunata Santoyo-Tepole ◽  
...  
Keyword(s):  
Steady State ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Inhibition Model

scholarly journals Fast Aqueous Biodegradation of Highly-Volatile Organic Compounds in a Novel Anaerobic Reaction Setup

Environments ◽  
2018 ◽  
Vol 5 (11) ◽  
pp. 115
Author(s):  
Yonhara García-Martínez ◽  
Judith Chirinos ◽  
Christophe Bengoa ◽  
Frank Stüber ◽  
Josep Font ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Substrate Inhibition ◽  
Packed Bed ◽  
Degradation Process ◽  
Inhibitory Effect ◽  
Packed Bed Reactor ◽  
Efficient System ◽  
Biological Activated Carbon ◽  
Volatile Organic

The present work explores the biodegradation of some emerging pollutants (EPs) in an anaerobic slowly-agitated up-flow packed-bed reactor (USPBR) filled with biological activated carbon (BAC). Chlorobenzene (CB) and 2,4-dichlorophenoxyacetic acid (2,4-D) were selected as volatile organic compounds (VOC) and major constituents of many pesticides. Experiments carried out in continuous operation showed that bioconversion up to 90% was achieved for CB and 2,4-D, at space times below 0.6 h and 1.2 h, respectively, at ambient temperature. Overall, removal rates of 0.89 g L−1 d−1 and 0.46 g L−1 d−1 were obtained for CB and 2,4-D, respectively. These results revealed that the degradation of CB and 2,4-D in this anaerobic configuration of bioreactor is an efficient and fast process. The Michaelis–Menten model properly describes the degradation process for CB. Above initial concentrations of 100 mg L−1, 2,4-D presented a considerable inhibitory effect over the biofilm. For this reason, a substrate inhibition factor was included in the Michaelis–Menten equation; the expanded model presented a good fitting to the experimental data, regardless of the inlet concentration. Therefore, USPBR-BAC combination showed to be a highly efficient system for the biodegradation of such compounds.

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