Analysis of the oscillatory behaviour of an industrial reactor for the oxonation of propene. Evaluation of flow models based on the response to a pulse signal

1987 ◽  
Vol 52 (6) ◽  
pp. 1454-1460
Author(s):  
Josef Horák ◽  
Zdeněk Bělohlav ◽  
František Madron
Keyword(s):  
Plug Flow ◽  
Pulse Signal ◽  
Radioactive Tracer ◽  
Oscillatory Behaviour ◽  
Back Flow ◽  
Flow Models ◽  
Industrial Reactor ◽  
Best Fit ◽  
Flow Element

The response of an industrial reactor for the oxonation of propene to its spiking with a radioactive tracer was compared with simulated responses obtained for models of various structures, viz. a cascade of two perfectly stirred cells of different size, a cascade of two perfectly stirred cells of the same size with recirculation of the reaction mixture, a cascade of two perfectly stirred cells of the same size with inflow into both cells, and a system of two perfectly stirred cells with back-flow involving a plug-flow element. None of the flow models fitted the experiment perfectly; the best fit was obtained for the combination of perfectly stirred cells and back-flow with a plug-flow element.

Analysis of the oscillatory behaviour of an industrial reactor for oxonation of propene; Combined models

1987 ◽  
Vol 52 (12) ◽  
pp. 2865-2875
Author(s):  
Josef Horák ◽  
Zdeněk Bělohlav ◽  
Petr Rosol ◽  
František Madron
Keyword(s):  
Liquid Phase ◽  
Dynamic Behaviour ◽  
Plug Flow ◽  
Equal Size ◽  
Mixed System ◽  
Oscillatory Behaviour ◽  
Industrial Reactor ◽  
Combined Models ◽  
Analysis Of Stability ◽  
Flow Element

Models have been used of the flow of the liquid phase in the reactor (cascade of two ideally mixed cells of different size, two equal-size cells with recycle, two equal-size cells with inlets to both cells and a model of two equal-size cells preceded with a back flow element with plug flow) to analyze the oscillatory states of an industrial reactor. Stable and instable steady states have been classified using analysis of pseudosteady states of conversion and temperature supplemented with a simulation of the dynamic behaviour. It has been that the deviations of the flow from an ideally mixed system may expand the region of the oscillatory behaviour. The detailed information about the character of the flow in the reactor and the way of feeding the reactor has been also found important for the analysis of stability.

scholarly journals Simple models for the continuous aerobic biodegradation of phenol in a packed bed reactor

2006 ◽  
Vol 49 (4) ◽  
pp. 669-676 ◽  
Author(s):  
Andrew Mark Gerrard ◽  
Jan Páca Júnior ◽  
Alena Kostecková ◽  
Jan Páca ◽  
Marie Stiborová ◽  
...  
Keyword(s):  
Plug Flow ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Aerobic Biodegradation ◽  
Rate Equations ◽  
Phenol Removal ◽  
First Order ◽  
Peak Loads ◽  
Linear Graphs ◽  
Best Fit

This paper proposes the use of a preliminary, phenol removal step to reduce peak loads arriving at a conventional effluent plant. A packed bed reactor (PBR) using polyurethane foam, porous glass and also cocoa fibres as the inert support material was used. Experiments have been carried out where the flow-rates, plus inlet and outlet phenol concentrations were measured. A simple, plug-flow model is proposed to represent the results. Zero, first order, Monod and inhibited kinetics rate equations were evaluated. It was found that the Monod model gave the best fit to the experimental data and allowed linear graphs to be plotted. The Monod saturation constant, K, is approximately 50 g m-3, and ka is around 900 s-1.

A Capillary Electrophoresis Platform With “On-Chip” Electrochemical Detection: Experimental and Computational Flow Studies

2001 ◽  
Author(s):  
Thomas J. Roussel ◽  
Robert S. Keynton ◽  
Kevin M. Walsh ◽  
Mark M. Crain ◽  
John F. Naber ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Electrochemical Detection ◽  
Power Supply ◽  
Electroosmotic Flow ◽  
Plug Flow ◽  
Finite Element Models ◽  
Separation Channel ◽  
Flow Models ◽  
On Chip ◽  
Electrochemical Potentials

Abstract The purpose of this study was to compare experimental electrokinetic plug flow velocities to computational flow models of microfabricated capillaries. Electroosmotic flow studies of dichlorofluorescein and electrophoretic separation of dopamine and catechol in a microfabricated capillary electrophoresis (CE) system were performed both experimentally and computationally. A “balanced cross design” consisting of a bent 2 cm long injection channel and a straight 2 cm long separation channel was used. The geometry of the capillary was 65 μm wide and 20 μm deep. For the fluorescein study, separation voltages ranging between 0.25 kV and 1 kV were applied, while voltages ranging from 100 V to 550 V were used in the separation studies. Laser Induced Fluorescent (LIF) images were obtained for flow visualization and qualitative analysis in the electroosmotic flow studies, while electrochemical potentials were acquired using “on-chip” electrodes interfaced to a custom-designed power supply and electrochemical detection (ECD) circuit. Finite element models of the experimental device were generated and flows were simulated using commercially available software. For the electroosmotic flow studies, the computational results were found to be within ± 11% of the experimentally obtained values. Similarly, the results of the computational separations of catechol and dopamine predicted plug velocities that were within ± 7.6% of the experimentally determined values.

Design Equations for Bod Removal in Facultative Ponds

1987 ◽  
Vol 19 (12) ◽  
pp. 187-193 ◽  
Author(s):  
E. Joe Middlebrooks
Keyword(s):  
Environmental Protection Agency ◽  
Linear Models ◽  
Plug Flow ◽  
Empirical Models ◽  
The Us ◽  
Non Linear ◽  
The Usa ◽  
Using Data ◽  
Removal Model ◽  
Best Fit

Facultative pond performance data collected for the US Environmental Protection Agency (USEPA) at four locations throughout the USA and data collected by others were used to evaluate the most frequently used design equations and to develop non-linear design equations. Empirical models were evaluated as well as the classical plug flow and complete mix models. The first order plug flow model gave the best fit of all the rational models. The empirical non-linear models did not fit the data, nor did the other empirical models with the exception being the areal loading and removal model. Attempts to verify the models developed with the USEPA data using data collected by others were not successful with the exception of the areal loading and removal model.

Ozone mass transfer in water treatment: hydrodynamics and mass transfer modeling of ozone bubble columns

2001 ◽  
Vol 1 (2) ◽  
pp. 123-130 ◽  
Author(s):  
M.G. El-Din ◽  
D.W. Smith
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Liquid Phase ◽  
Plug Flow ◽  
Axial Dispersion ◽  
Bubble Columns ◽  
Algebraic Equations ◽  
Mixed Flow ◽  
Back Flow ◽  
Linear Algebraic Equations

Most of the mathematical models that are employed to model the performance of bubble columns are based on the assumption that either plug flow or complete mixing conditions prevail in the liquid phase. Although due to the liquid-phase axial dispersion, the actual flow pattern in bubble columns is usually closer to being mixed flow rather than plug flow, but still not completely mixed flow. Therefore, the back flow cell model (BFCM), that hypothesises both back flow and exchange flow to characterise the liquid-phase axial dispersion, is presented as an alternative approach to describe the hydrodynamics and mass transfer of ozone bubble columns. BFCM is easy to formulate and solve. It is an accurate and reliable design model. Transient BFCM consists of NBFCM ordinary-first-order differential equations in which NBFCM unknowns (Yj) are to be determined. That set of equations was solved numerically as NBFCM linear algebraic equations. Steady-state BFCM consists of 3 × NBFCM non-linear algebraic equations in which 3 × NBFCM unknowns (qG,j, Xj, and Yj) are to be determined. Those non-linear algebraic equations were solved numerically using Newton–Raphson technique. Steady-state BFCM was initially tested using the pilot-scale experimental data of Zhou. BFCM provided excellent predictions of the dissolved ozone profiles under different operating conditions for both counter and co-current flow modes.

Comparison between dispersion and plug-flow models for fixed-bed enzyme reactors

AIChE Journal ◽  
1992 ◽  
Vol 38 (9) ◽  
pp. 1477-1480 ◽  
Author(s):  
Robert Lortie ◽  
Dominique Pelletier
Keyword(s):  
Plug Flow ◽  
Fixed Bed ◽  
Flow Models ◽  
Enzyme Reactors
Sign in / Sign up

Export Citation Format

Share Document