Dynamic behavior of a counter-current fixed-bed reactor with sustained oscillations

2000 ◽  
pp. 205-210
Author(s):  
M. Mangold ◽  
F. Klose ◽  
E.D. Gilles
Keyword(s):  
Dynamic Behavior ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Sustained Oscillations ◽  
Counter Current

scholarly journals Dynamic Simulation of Adiabatic Catalytic Fixed-Bed Tubular Reactors: A Simple Approximate Modeling Approach

2014 ◽  
Vol 14 (1) ◽  
pp. 25
Author(s):  
Wiwut Tanthapanichakoon ◽  
Shinichi Koda ◽  
Burin Khemthong
Keyword(s):  
Dynamic Model ◽  
Dynamic Behavior ◽  
Dynamic Simulation ◽  
Flow Rate ◽  
Fixed Bed ◽  
Axial Dispersion ◽  
Fixed Bed Reactor ◽  
Inlet Temperature ◽  
Acetylene Hydrogenation ◽  
Tubular Reactors

Fixed-bed tubular reactors are used widely in chemical process industries, for example, selective hydrogenation of acetylene to ethylene in a naphtha cracking plant. A dynamic model is required when the effect of large fluctuations with time in influent stream (temperature, pressure, flow rate, and/or composition) on the reactor performance is to be investigated or automatically controlled. To predict approximate dynamic behavior of adiabatic selective acetylene hydrogenation reactors, we proposed a simple 1-dimensional model based on residence time distribution (RTD) effect to represent the cases of plug flow without/with axial dispersion. By modeling the nonideal flow regimes as a number of CSTRs (completely stirred tank reactors) in series to give not only equivalent RTD effect but also theoretically the same dynamic behavior in the case of isothermal first-order reactions, the obtained simple dynamic model consists of a set of nonlinear ODEs (ordinary differential equations), which can simultaneously be integrated using Excel VBA (Visual BASIC Applications) and 4th-order Runge-Kutta algorithm. The effects of reactor inlet temperature, axial dispersion, and flow rate deviation on the dynamic behavior of the system were investigated. In addition, comparison of the simulated effects of flow rate deviation was made between two industrial-size reactors.Keywords: Dynamic simulation, 1-D model, Adiabatic reactor, Acetylene hydrogenation, Fixed-bed reactor, Axial dispersion effect

scholarly journals Investigation of the Olive Mill Solid Wastes Pellets Combustion in a Counter-Current Fixed Bed Reactor

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1965 ◽  
Author(s):  
Mohamed Mami ◽  
Hartmut Mätzing ◽  
Hans-Joachim Gehrmann ◽  
Dieter Stapf ◽  
Rainer Bolduan ◽  
...  
Keyword(s):  
Reaction Front ◽  
Mass Loss Rate ◽  
Fixed Bed ◽  
Solid Wastes ◽  
Fixed Bed Reactor ◽  
Electricity Production ◽  
Wood Pellets ◽  
Bed Temperature ◽  
Counter Current ◽  
Olive Mill

Combustion tests and gaseous emissions of olive mill solid wastes pellets (olive pomace (OP), and olive pits (OPi)) were carried out in an updraft counter-current fixed bed reactor. Along the combustion chamber axis and under a constant primary air flow rate, the bed temperatures and the mass loss rate were measured as functions of time. Moreover, the gas mixture components such as O2, organic carbon (Corg), CO, CO2, H2O, H2, SO2, and NOx (NO + NO2) were analyzed and measured. The reaction front positions were determined as well as the ignition rate and the reaction front velocity. We have found that the exhaust gases are emitted in acceptable concentrations compared to the combustion of standard wood pellets reported in the literature (EN 303-5). It is shown that the bed temperature increased from the ambient value to a maximum value ranging from 750 to 1000 °C as previously reported in the literature. The results demonstrate the promise of using olive mill solid waste pellets as an alternative biofuel for heat and/or electricity production.

Role of filter media in an anaerobic fixed-bed reactor

1995 ◽  
Vol 31 (9) ◽  
pp. 137-144 ◽  
Author(s):  
T. Miyahara ◽  
M. Takano ◽  
T. Noike
Keyword(s):  
Anaerobic Bacteria ◽  
Fixed Bed ◽  
Methanogenic Bacteria ◽  
The Other ◽  
Fixed Bed Reactor ◽  
Filter Media ◽  
Fixed Bed Reactors ◽  
Attached Bacteria ◽  
The Relationship

The relationship between the filter media and the behaviour of anaerobic bacteria was studied using anaerobic fixed-bed reactors. At an HRT of 48 hours, the number of suspended acidogenic bacteria was higher than those attached to the filter media. On the other hand, the number of attached methanogenic bacteria was more than ten times as higher than that of suspended ones. The numbers of suspended and deposited acidogenic and methanogenic bacteria in the reactor operated at an HRT of 3 hours were almost the same as those in the reactor operated at an HRT of 48 hours. Accumulation of attached bacteria was promoted by decreasing the HRT of the reactor. The number of acidogenic bacteria in the reactor packed sparsely with the filter media was higher than that in the closely packed reactor. The number of methanogenic bacteria in the sparsely packed reactor was lower than that in the closely packed reactor.

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

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