bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Method for Identifying Osmotically Limited and Gel Layer Controlled Pressure Independent Flux in Ultrafiltration
Authors: Zaidi S. K. , Karode S. K. , Kirpalani D , Kumar A
Published: July 2010

An unequivocal determination of whether pressure independent flux regime is osmotically controlled or gel layer dominated, is still open for discussion in the membrane literature. The present work reports a method that could be used to address this issue. It is shown that analysis of post steady state transient filtration data leads to clear demarcation of osmotically limited and gel layer controlled filtration. The method proposed in this work can also be used to estimate the additional filtration resistance offered by the polarization layer to the permeate flow in macromolecular ultrafiltration and has been verified experimentally. It has also been shown that the polarization layer thickness is not sensitive to the feed pressure but varies as a function of the bulk solute concentration; higher the bulk concentration, thicker is the polarization layer.
Evaluation of Polyester Resin as a New Compatibilizer for SBR/PVC Blends
Authors: Abd‐El‐Messieh S. L. , Mansour S. H. , El‐Nashar D , Ikladious N. E.
Published: July 2010

A polyester (PE) based on the glycolyzed products of PET was prepared and added in different concentrations to a series of SBR/PVC blends. The addition of the polyester showed that all properties of SBR/PVC blends were improved by incorporation of PE. Highest mechanical strength values were obtained at a polyester concentration of 7.5 phr. Thermal analysis as well as dynamic mechanical properties of SBR/PVC blends after the addition of 7.5 and 10 phr polyester indicated one single glass transition temperature. The dielectric losses (ϵ") were analyzed in the frequency domains in the two terms of Fröhlich related to the Maxwell Wagner effect and the orientation of the aggregates caused by the movement of the main chain. The permittivity (ϵ') values were found to increase by increasing the polyester content. This increase was followed by a decrease in the ϵ" up to a 7.5 phr polyester content after which no pronounced change was noticed.
Numerical Investigation of Resonance Behaviour of a Tubular Packed‐Bed Reactor with Non‐Uniform Activity
Authors: Jaree Attasak , Hudgins Robert R. , Budman Hector M. , Silveston Peter L. , Menzinger Michael
Published: July 2010

The effects of periodic temperature perturbations at the inlet of a packed‐bed catalytic reactor were investigated for a system of non‐uniform catalyst activity that could arise through catalyst deactivation. A simplified model consisting of zones of active catalyst and inert packing of similar thermal properties was assumed. Simulations showed that large amplification, expressed as gain, can occur. The largest gain is observed at a resonance frequency. Both gain and resonance frequency depend on the number of layers of active catalyst and inert packing, the depth of the inert packing and catalyst layers.
Size Segregation of Nickel Pellets Flowing into a Packed Bed
Authors: Moysey Paul A. , Rama Rao Nadella V. , Baird Malcolm H. I.
Published: July 2010

The size segregation of nickel pellets fed to a packed bed has been measured with mixtures of sizes ranging from less than 1 mm to about 10 mm. The pellet mixture is fed to one side of a rectangular cell and then samples are removed from different lateral positions in the cell for screen analysis. During the feeding process the finer pellets tend to percolate vertically downwards while the larger pellets tend to roll down the sloping surface of the bed. The resulting segregation has been correlated with the size distribution of the feed pellets and the lateral position in the cell, using polynomial equations with three or four adjustable coefficients.
Kinetics of Bitumen‐Derived Gas Oil Upgrading Using a Commercial NiMo/Al2O3 Catalyst
Authors: Botchwey Christian , Dalai Ajay K. , Adjaye John
Published: July 2010

Hydrotreating (HT) kinetics of Athabasca bitumen‐derived gas oil has been studied between 340 to 420°C using a commercial NiMo/γ‐Al2O3 catalyst. The kinetics analyses included overall conversion of high‐boiling species into low‐boiling products, hydrodenitrogenation (HDN) of total, basic and non‐basic nitrogen compounds and hydrodesulfurization (HDS). Three temperature regimes were marked out for the kinetic analyses: low (340‐370°C), intermediate (370‐400°C) and high (400‐420°C). The mechanism for the conversion of high to low‐boiling species was observed to change from one temperature regime to the other, giving rise to different activation energies. HDS and HDN activation energies increased in the order: high < low < intermediate severity temperature regime.
Comparison of Internal and External Mixer Spargers in a Laboratory De‐inking Flotation Column
Authors: Hardie C. A. , Gomez C. O. , Finch J. A.
Published: July 2010

Column flotation has been introduced for waste paper de‐inking to take advantage of low capital cost and excellent separation performance. Bubble generation employs a variety of systems, broadly divided into two types: internal and external. An external in‐line static mixer sparger was tested against an internal porous stainless steel sparger. They were compared in an industrial de‐inking facility using a 10 cm diameter column. Operating conditions were defined and the effect of gas rate, retention time, wash water rate, and froth height on de‐inking was investigated. Both spargers gave similar ink recovery and fiber loss as a function of bubble surface area flux. However, the static mixer gave stable operation while the porous sparger showed evidence of plugging over a 6h test. Combined with some ability to control bubble size, overall the in‐line static mixer gave superior performance.
Optimization of Reaction Conditions in a Fluidized‐Bed for Silane Pyrolysis
Authors: Tejero‐Ezpeleta Maria P. , Buchholz Sigurd , Mleczko Leslaw
Published: July 2010

The fluidized‐bed chemical vapor deposition (CVD) process for polycrystalline silicon production is considered to be the most attractive alternative to the conventional bell‐jar process. In order to obtain stable operation, high space‐time‐yields and high purity of the product several obstacles have to be eliminated. Reaction conditions must be optimized to avoid the homogeneous decomposition of silane and minimize silicon dust formation. The effect of temperature, silane partial pressure, gas velocity and the size of bed particles has to be identified. These dependencies and the interaction between hydrodynamics and kinetics of homogeneous and heterogeneous CVD‐reactions were studied in a laboratory‐scale fluidized‐bed reactor.
A Hydration Shell‐Based Thermodynamic Model for Aqueous Two‐Phase Systems
Authors: De Alcântara Pedro , Filho Pessôa , Mohamed Rahoma S.
Published: July 2010

In this work a Flory‐Huggins model modified to account for some unique features of Aqueous Two‐Phase Systems is presented. The model takes into account observed solvation between water and polymer molecules through the incorporation of a hydration shell to express the number of water molecules bonded to each polymer molecule. The parameters of the modified equation were determined using experimental data of ATPS containing poly (ethylene glycol) and dextran. The results revealed remarkable improvement in the correlation ability of the model. A general expression that defines the number of water molecules in the hydration shell was also obtained.
Understanding Water‐Based Bitumen Extraction from Athabasca Oil Sands
Authors: Masliyah Jacob , Zhou Zhiang Joe , Xu Zhenghe , Czarnecki Jan , Hamza Hassan
Published: July 2010

The current state of knowledge on the fundamentals of bitumen recovery from Athabasca oil sands using water‐based extraction methods is reviewed. Instead of investigating bitumen extraction as a black box, the bitumen extraction process has been discussed and analyzed as individual steps: Oil sand lump size reduction, bitumen liberation, aeration, flotation and interactions among the different components that make up an oil sand slurry. With the development and adoption of advanced analytical instrumentations, our understanding of bitumen extraction at each individual step has been extended from the macroscopic scale down to the molecular level. How to improve bitumen recovery and bitumen froth quality from poor processing ores is still a future challenge in oil sands processing.
Interaction between Bitumen and Fines in Oil Sands Extraction System: Implication to Bitumen Recovery
Authors: Liu Jianjun , Xu Zhenghe , Masliyah Jacob
Published: July 2010

Colloidal interactions between bitumen and fines, extracted directly from oil sand ores, were investigated with zeta potential distribution measurement and surface force measurement using an atomic force microscope (AFM). Fines from good processing ores exhibit a negligible attachment to bitumen surfaces, due to hydrophilic nature of the fines. Fines from poor processing ores exhibit a stronger attachment to bitumen surfaces by an attractive hydrophobic force between bitumen and fines, due to hydrophobic nature of the fines and the presence of high concentration divalent cations in the processing water.
Fines/Water Interactions and Consequences of the Presence of Degraded Illite on Oil Sands Extractability
Authors: Wallace Dean , Tipman Robert , Komishke Brad , Wallwork Vince , Perkins Ernie
Published: July 2010

The chemical composition of the aqueous phase in oil sand slurries influences bitumen recovery from oil sands, especially those containing greater than 10% fines. The composition is controlled by a combination of mixing and dilution, ion exchange with clay surfaces and precipitation of divalent ions as carbonate minerals. Elevated levels of soluble potassium in the oil sand, which appear to be a marker for degraded illite or smectitic clays, are associated with depressed bitumen recovery. These clays have a swelling character and can contribute divalent ions to the slurry by ion exchange between the clay mineral surfaces and the process water.
A Perspective on the Selection of Froth Treatment Processes
Authors: Shelfantook William E.
Published: July 2010

Treating of froths produced in extraction plants processing surface‐mined oilsand presents an interesting and challenging array of problems. Much of what we do to the feed ore to maximize recovery of bitumen creates surfactant/biwettable solids mixtures that stabilize water‐in‐oil emulsions. These persist despite our most strenuous attempts to break them. Temperature and solvent selection both influence the performance of froth treatment processes. However, often we do not look at the broader implications of either in new or expanding ventures. This paper presents another perspective, showing how both temperature and solvent selection influence the outcome of froth treatment.
Investigation of Oil Sands Froth Treatment
Authors: Romanova Uliana G. , Yarranton Harvey W. , Schramm Laurier L. , Shelfantook William E.
Published: July 2010

Two oil sand froth treatment methods are investigated: 1) dilution with an aromatic solvent followed by centrifugation (AS Method); 2) dilution with a paraffinic solvent followed by gravity settling (PS Method). The effectiveness of the methods is assessed in terms of bitumen recovery and the water content in the recovered diluted bitumen. The optimum solventto‐bitumen ratios are identified considering process type, ore quality, temperature, and residence time.
Effects of Sand Fraction on Toluene‐diluted Heavy Oil in Water Emulsions in Turbulent Flow
Authors: Angle Chandra W.
Published: July 2010

The impact of the presence of sand on emulsification of toluene‐diluted heavy oil in simulated process water was systematically studied as a function of agitation time, in a stirred tank. Droplet size distributions were measured by light scattering technique. Optical microscopy and high‐speed video micrography were used to visually monitor agitation and emulsion stability. Results showed that the Sauter mean diameters of the droplets decreased with increasing sand content. Droplet breakage followed a first‐order kinetic model for all mixing speeds. Plots of droplet volume percent frequency versus droplet size followed lognormal distribution. The distribution span broadened into lower sizes with increased sand content. Emulsions were stable for over 48 h after formation.
A Bench‐Scale Study of Conditioning Behaviour in Oil Sands Slurries
Authors: Friesen Waldemar I. , Dabros Tadeusz , Kwon Teddy
Published: July 2010

Proper conditioning of an oil sand/water slurry is essential for the efficient extraction of bitumen. The conditioning process depends on such variables as ore grade, temperature, mixing intensity, mixing time, and water composition. A technique has been developed in which a microscope and video cameras are used to observe a slurry stirred in a glass cell to evaluate, on a comparative basis, the effect of conditioning parameters on bitumen recovery. Several ores and their blends were studied and found to exhibit large differences in their conditioning behaviour. The method offers the capability of diagnosing ore processability problems and optimizing slurry conditioning.
Analysis of Solvent‐Diluted Bitumen from Oil Sands Froth Treatment Using NIR Spectroscopy
Authors: Long Yicheng , Dabros Tadeusz , Hamza Hassan
Published: July 2010

Process control and optimization of bitumen froth treatment during oil sands processing require rapid analysis of asphaltene content in bitumen, solvent‐tobitumen ratio (S/B), and the density of solvent‐diluted bitumen. NIR spectroscopy was employed to meet this requirement. The NIR system comprised a spectrometer with no moving parts coupled with a double‐pass transflectance probe via a fiber‐optic cable. Quantitative calibration models were established using partial leastsquares regression in latent variables. The standard errors of calibration were 0.20 wt% for 0 to 20 wt% asphaltenes in bitumen, 1.1 wt% for 20 to 100 wt% asphaltenes in bitumen, 0.1 for S/B of solvent‐diluted bitumen, and 0.0017 g/mL for density of solvent‐diluted bitumen. It was shown that the process conditions could be monitored through the spectral scores from principal component analysis.
Adhesion of Bitumen to a Metal Surface in a Flowing Oil Sands Slurry
Authors: Xu Yuming , Dabros Tadeusz , Friesen Waldemar I. , Maciejewski Waldemar B. , Czarnecki Jan
Published: July 2010

Bench‐scale experiments were conducted to study the behaviour of oil sands slurries. While a slurry was being stirred with a standard impeller, the mass of bitumen, Mad, that adhered to a steel probe dipped into the slurry was measured. Mad remained small up to a critical adhesion time, τad, and then increased rapidly. τad depended on ore grade, temperature, pH, and clay content. The implication for hydrotransport of oil sands is clear: τad should be greater than the residence time of the slurry to avoid the problem of bitumen coating the pipe wall and the attendant increase in pumping pressure.
Langmuir and Langmuir‐Blodgett Asphaltene Films at Heptane‐water Interface
Authors: Lawrence Steven , Zhang Li Yan , Xu Zhenghe , Masliyah Jacob
Published: July 2010

Monolayer characteristics of subfractions and unfractionated whole asphaltenes from Athabasca oil sands bitumen were studied at heptane‐water interface. The transferred Langmuir‐Blodgett films of asphaltenes were characterised with atomic force microscopy and contact angle measurements. Monolayers prepared from the three asphaltene samples are found to behave similarly at heptane‐water interface. The high molecular weight asphaltene monolayer is the most expanded one whereas the low molecular weight asphaltene monolayer is the most condensed one. An asphaltene monolayer behaves differently at an airwater interface to a heptane‐water interface. The presence of the bulk heptane phase renders the interfacial asphaltene monolayer more flexible as compared to that at air‐water interface.
Performance of Sand Slurry Pipelines in the Oil Sands Industry
Authors: Sanders R Sean , Schaan Jason , Hughes Roxby , Shook Clifton
Published: July 2010

Operating data for several slurry pipelines in the Alberta oil sand industry have been sampled and interpreted with the assistance of the Saskatchewan Research Council (SRC) Two‐Layer model. The slurries are described within the industry as normal tailings, dense tailings, or oil sand slurries. All are of the so‐called heterogeneous or settling slurry type. The pipelines considered ranged in diameter between 0.483 m and 0.737 m. The useful operating data included water and slurry pressure drop measurements recorded during periods in which velocities and densities were nearly constant. The data reveal that the friction is often higher than predicted by the SRC Two‐Layer model, which makes no allowance for the effect of large particles (>50 mm) which are known to be present. This friction increment appears to be higher when the pipelines have sections with upward slopes.
Flow Regime Identification in a Slurry Bubble Column from Gas Holdup and Pressure Fluctuations Analysis
Authors: Barghi S , Prakash A , Margaritis A , Bergougnou M. A.
Published: July 2010

Analysis of gas holdups and pressure fluctuations are conducted in a slurry bubble column to study changes in flow regimes and comparisons are made with solid‐free bubble column. The pressure fluctuations are measured by fast response pressure transducers mounted on the column wall in the distributor and bulk regions. Air, tap water and 35 micron glass beads are used as the gas, liquid and solid phases respectively. Statistical analysis of pressure fluctuation data combined with gas holdup analysis provided information about flow regime transition and interesting insights into bubble size distributions and changes in flow structure.
Oxygen Transfer in a Baffled Rectangular Air‐Lift Loop Reactor
Authors: Couvert Annabelle , Bastoul Dominique , Roustan Michel , Chatellier Patrice
Published: July 2010

The objective of this study is to characterize mass transfer in a rectangular air‐lift loop reactor in two‐phase flow. In a previous work, it has been shown that the reactor presents a complex gas flow pattern. Therefore, first, the global mass transfer volumetric coefficient kLa was measured in two‐phase flow, by three methods (two based on the liquid phase mass balance, one based on the gas phase mass balance). Then, second, a localized analysis was implemented in order to obtain more information about the phenomena governing the gas phase flow.
Determination of Nucleation and Crystal Growth Kinetics in Hostile Environment – Application to the Tetravalent Uranium Oxalate U(C2O4)2. 6H2O
Authors: Bertrand‐Andrieu Murielle , Plasari Edouard , Baron Pascal
Published: July 2010

A specific apparatus and an original batch method are developed for, respectively, nucleation and crystal growth rate measurements in a hostile environment, such as glove box. Primary nucleation and crystal growth kinetic rates for uranium oxalate are measured over a wide range of temperatures and solution concentrations. The nucleation rate obeys the Volmer‐Weber equation, with activation energies of 182 kJ.mol−1 for the homogeneous nucleation and 102 kJ.mol−1 for the heterogeneous one. The crystal growth rate is first order with respect to the supersaturation and controlled by a surface integration mechanism, characterized by a 29 kJ.mol−1 activation energy.
Dehydration of Methanol to Dimethyl Ether by Catalytic Distillation
Authors: An Weizhu , Chuang Karl T. , Sanger Alan R.
Published: July 2010

The kinetics of liquid catalytic dehydration of methanol over an ion exchange resin (Amberlyst 35) has been determined for the temperature range 343 to 403 K using a batch reactor. The experimental data are described well by an Eley‐Rideal type kinetic expression, for which the surface reaction is the rate‐determining step. A catalytic distillation process for methanol dehydration to dimethyl ether (DME) has been modeled using the experimentally determined kinetic data. The results were incorporated into the rate‐controlled reaction mode for RadFrac, a part of the commercial simulation program Aspen Plus. It was shown that synthesis of high purity DME can be achieved using a single catalytic distillation column. Thus there is significant potential for reduction of overall capital cost for a plant for methanol dehydration to DME when compared to conventional production facilities that involve separate reaction and distillation processes.
Analysis of Drying Kinetics of Iron Ores using Irreversible Thermodynamics and Transport Phenomena Principles
Authors: Oliveira Idalmo M. , Seshadri Varadarajan , Mansur Marcelo B.
Published: July 2010

Drying kinetics of iron ores, the primary raw material for the iron and the steel industry, has been studied in this work. Experimental drying kinetics and equilibrium moisture content data have been obtained using thermogravimetric techniques at controlled conditions of humidity, temperature and gas flow. A theoretical model based on the principles of irreversible thermodynamics and transport phenomena, and a computer program for the simulation of drying process has been developed (SimDry 1.0 for Windows). The results of simulation have been compared with the experimental results and there has been reasonable agreement between them.
Experimental and Numerical Modeling Studies of Arsenic Removal with Wood Ash from Aqueous Streams
Authors: Rahman Mohammod H. , Wasiuddin Nazimuddin M. , Islam M Rafiqul
Published: July 2010

Most of the arsenic removal processes are not cost‐effective and/or not efficient in removing As (III). In this research, it was found that Maple wood ash has the potential to adsorb both As (III) and As (V) from contaminated aqueous streams at low concentration levels without any chemical treatment. Static tests showed up to 80% arsenic removal and in various dynamic column tests the arsenic concentration was reduced from 500 ppb to lower than 5ppb. Finally, the ash column was modeled using the surface excess theory. The identified model significantly facilitates practical design of arsenic adsorption system.
Water‐Based Bitumen Recovery from Diluent‐Conditioned Oil Sands
Authors: Hupka Jan , Miller Jan D. , Drelich Jaroslaw
Published: July 2010

Important process development aspects leading to more efficient bitumen recovery from diluent‐conditioned oil sands by water‐based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand‐diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low‐viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase.
Dispositif de déposition de couches de suspensions de céramiques appliqué à la stéréolithographie
Authors: Dufaud Olivier , Corbel Serge
Published: July 2010

Un dispositif de déposition de couches uniformes de suspensions de céramiques a été mis au point en vue d'applications pour le prototypage rapide. Le système de raclage se compose d'une buse d'injection de gaz de hauteur, d'angle d'attaque et de pression réglables. L'homogénéité des couches étalées ainsi que la reproductibilité du procédé ont été étudiées. La mise en place d'un plan d'expérience a également conduit à la caractérisation de l'influence de chaque paramètre sur l'épaisseur de couche déposée et a permis de proposer un modèle mathématique fiable en vue d'optimiser le dispositif de dépôt.
Surface Tensions of Hydrocarbons and Bitumens at High Temperatures and Pressures
Authors: Millette Jacques , Scott Donald S. , Radlein Desmond , Piskorz Jan , Majerski Piotr , Reilly Irvine G. , Debruijn T. J. W.
Published: July 2010

A maximum bubble pressure apparatus, described in a previous publication, has been used at pressures to 13.9 MPa (2000 psig) and temperature to 623 K (350°C) to measure the static surface tension of several alkanes and paraffinic petroleum fractions, and two types of Alberta bitumens in contact with hydrogen, helium and hydrogen/methane mixtures. With hydrogen, the surface tensions of alkanes or mixtures of alkanes were nearly independent of pressure, whereas with helium surface tension increased significantly. With hydrogen/methane mixtures, the surface tension decreased in value as pressure increased, with the effect increasing at the higher methane concentrations. For the two bitumens used, the surface tension with hydrogen showed a 10–15% increase as pressure increased at constant temperature. Some discussion is also given concerning methods of predicting the effects of pressure and temperature in hydrogen/hydrocarbon systems.
Pressure Fluctuations in Jet Spouted Beds
Authors: Leu Lii‐Ping , Pan Rong‐Shyan
Published: July 2010

Jet spouted beds that consisted of a transparent Plexiglas cylindrical column of 1 m high and a conical base with cone angles of 30°, 36°, and 40° were used in this study. The particles used were spherical glass beads with an average diameter of 1.7, 2.1 and 3 mm, respectively, and particle size of 2.2 – 3.1 mm, non‐spherical rice particles. The effect of size and shape of particles, and static bed height on the minimum jet spouting velocity, and standard deviation of pressure fluctuations, was investigated. The results show that the minimum jet spouting velocity and pressure drop increased as the bed height and particle size increased. The minimum jet spouting velocity could be determined from the plot of standard deviation of pressure fluctuations vs. superficial gas velocity. The results obtained were in close agreement with the results of other methods in the literature.
Homogeneous Fluidization Characteristics of Vibrating Fluidized Beds
Authors: Jin Haibo , Tong Zemin , Zhang Jiyu , Zhang Bijiang
Published: July 2010

The effects of vibration parameters, operating conditions and material properties on fluidization quality were investigated by the measurement and analysis of voidage fluctuation signals in a vibrating fluidized bed with a diameter of 148 mm. The fluctuation deviation of the bed voidage and the enhancement index of the bed derived can describe bed homogeneity and its extension. A new criterion of homogeneity, consisting of the material parameter (Ar), operating parameters (H0, u/umf) and vibration parameters (a, ω), is proposed to predict a suitable range of homogeneous fluidization. Experimental results on eight kinds of solids, five static bed heights and different vibration parameters were used to propose guidelines for the reasonable selection of operating conditions for vibrating fluidization and better operating conditions.
Effect of Non‐Newtonian Characteristics on Convective Liquid‐Solid Heat Transfer in Packed and Fluidised Beds of Spherical Particles
Authors: Shukla Rupali , Chhabra R. P.
Published: July 2010

In this work, the field (continuity, momentum and thermal energy) equations togetherwith a cell model have been solved numerically to elucidate the influence of non‐Newtonian (Power law rheology) liquid characteristics on liquid‐solid heat transfer in packed and fluidised beds of spherical particles. The results presented herein relate to wide ranges of conditions of bed voidage, power‐law index and Peclet number but are limited to low Reynolds number (≤1) flow conditions. Within the range of conditions, the effect of power‐law index is found to be small and this is also consistent with the available experimental results on liquid‐solid mass transfer in these systems.
Efficient Phase Equilibrium Calculation in a Reduced Flash Context
Authors: Nichita Dan Vladimir , Minescu Florea
Published: July 2010

A new and efficient method for phase equilibrium calculations using cubic equations of state (EOS) has been developed. The reduced flash technique presented here takes into account non‐zero binary interaction coefficients (BIC's), and requires the iterative correction of a reduced number of independent variables (2m+3, where m is the number of components with non‐zero BIC's), irrespective of the number of components in the mixture. A new extrapolation procedure, called the Direct Reduced Flash Calculation (DRFC) is formulated. Calculations performed for several hydrocarbon mixtures with emphasis to the near‐critical region prove the robustness and the efficiency of the proposed method.
Fault Detection and Diagnosis in a Food Pasteurization Process with Hidden Markov Models
Authors: Tokatli Figen Kosebalaban , Cinar Ali
Published: July 2010

Hidden Markov Models (HMM) are used to detect abnormal operation of dynamic processes and diagnose sensor and actuator faults. The method is illustrated by monitoring the operation of a pasteurization plant and diagnosing causes of abnormal operation. Process data collected under the influence of faults of different magnitude and duration in sensors and actuators are used to illustrate the use of HMM in the detection and diagnosis of process faults. Case studies with experimental data from a high‐temperature‐short‐time pasteurization system showed that HMM can diagnose the faults with certain characteristics such as fault duration and magnitude.
The Effects of Power Law Fluid Rheology on Coil Heat Transfer for Agitated Vessel in the Transitional Flow Regime
Authors: Ricci Eric , Kelly William J.
Published: July 2010

A CFD model of heat transfer from power‐law fluids to helical cooling coils in the transitional flow regime of a baffled tank mixed with a pitched blade turbine was developed with FluentTM. The model captured local temperature and velocity gradients. Simulations were run, varying Re, Pr, K and n. The results indicate that a Sieder‐Tate type correlation, with the exponent on and the coefficient in front of the Reynolds number being a function of n, is recommended for estimating ho. Also, a new two coil bank design was found to be more efficient when 450 < Re < 650.
The Impact of Local Phenomena on Mass Transfer in Gas‐Liquid Systems
Authors: Bork Olaf , Schlueter Michael , Raebiger Norbert
Published: July 2010

The impact of local phenomena on mass transfer from single bubbles and bubbles rising under swarm conditions with the bubble diameter and the viscosity as variation parameters is investigated by using laser‐induced fluorescence. It is reported that the wake shedding frequency of ellipsoid bubbles is decisively responsible for the convective mass transfer. A novel mass transfer correlation is developed considering the Strouhal number and swarm conditions.
Heat Removal from Reverse Flow Reactors Used in Methane Combustion
Authors: Balaji Sukumar , Lakshminarayanan S.
Published: July 2010

The idea of using Reverse Flow Reactors (RFR) for methane reduction in exhausts has been well elucidated in the past. However, there are intricacies in such operations to maintain the ignited state of the reactor along with maintaining low outlet concentrations of methane. This is especially true under rich feed conditions where combustion reactions liberate more heat leading to possible catalyst deactivation. Under favourable conditions, it is possible to continuously extract heat from the RFR system‐this is a viable way of maintaining acceptable thermal conditions in the reactor and consequently retaining catalyst activity. This paper elaborates upon the optimal amount of heat that can be removed from the system without losing the sustainability while preventing overheating of the catalyst bed. A simple event based control strategy is implemented for switching the inlet and outlet ports (flow reversal). Issues relating to the operation of reverse flow reactors with side feeding and the possibility of extraction of useful heat from such systems are also discussed. Methane combustion reaction and a continuous two dimensional heterogeneous model of the reactor have been employed in this study.
Simulation of Radiation Field in Multilamp Photoreactor Using the LSDE Model
Authors: Yang Quan , Pehkonen S. O. , Ray Madhumita B.
Published: July 2010

Determination of a radiation field in a multilamp photoreactor is rather difficult due to the blockage of light by the neighbouring lamps in the reactor. Shadow zones in the photoreactor caused by the lamp blockage vary according to the different lamp arrangements. In addition, the reactor shape also has an effect on the average light intensity, since light is absorbed by the reactor wall if it reaches the wall. In this study, selected aspects of reactor configuration and lamp arrangement were investigated in order to achieve the maximum average light intensity. A line source with a diffused emission (LSDE) model, which shows sufficient accuracy and simplicity, was selected to simulate the light field in the test reactor. Simulation indicates that the square and cylindrical reactors with two and four lamps installed symmetrically exhibited superior performance to elliptical and rectangular reactors. For a multilamp reactor, a triangular pitch of lamp arrangement with 33° is recommended for maximum average light intensity.
A Comparison of PID Controller Tuning Methods
Authors: Foley Michael W. , Julien Rhonda H. , Copeland Brian R.
Published: July 2010

The derivative mode is often omitted in PID control strategies because it proves difficult to arrive by trial‐and‐error at a set of constants which meet plant requirements. The primary objective of this paper was to evaluate several model‐based PID tuning methods. For lag‐dominant processes, it was recommended that the SIMC algorithm first be employed to determine whether satisfactory performance can be obtained with PI control. If it cannot, then derivative action should be introduced using the DS‐d technique. For delay‐dominant systems, IMC tuning is preferred. It was observed that when configured with the same derivative filter factor, the series form of the PID controller produces smoother valve adjustments than the parallel version, at the expense of a slight decrease in best achievable performance. Increasing this parameter improves the control effort but limits achievable performance.
Méthodologie d'étude et de modélisation de la déphosphatation d'effluents aqueux
Authors: Montastruc L. , Domenech S. , Pibouleau L. , Azzaro‐Pantel C.
Published: July 2010

En raison de l'impact des phosphates sur la pollution des eaux, un procédé de récupération par précipitation d'un phosphate de calcium a été développé. Le réacteur du procédé est un lit fluidisé, dans lequel le phosphate précipite en continu et s'enrobe sur des grains de sable. Le pilote réalisé permet de traiter des débits de rejet aqueux synthétique ([P]in = 50 mg/l) de l'ordre de 0,1 m3/h. La méthodologie découple les phéno‐mènes physico‐chimiques présents. La précipitation dans le lit fluidisé est modélisée à l'aide de concepts thermodynamiques tenant compte des différents phosphates de calcium susceptibles de précipiter en fonction des conditions opératoires (pH, [P], [Ca], T). L'enrobage est modélisé par une réaction cinétique du premier ordre entre les fines et les grains de sable, couplée avec un réseau de réacteurs idéaux traduisant l'hydrodynamique du système.
The Effect of Particle Size Distribution on Pressure Drop through Packed Beds of Cooked Wood Chips
Authors: Lee Quak Foo , Bennington Chad P. J.
Published: July 2010

The pressure drop of process liquors through columns of wood chips determines the operability, efficiency and control of both batch and continuous pulp digesters and the quality of the pulp produced from them. Pressure drop was measured through columns of industrial white spruce chips (produced with a chipping head‐rig) as a function of the chip size distribution and the extent of delignification. Flow resistance depended on the porosity of the chip bed which was affected by the kappa number of the chips (which affected their flexibility) and chip size distribution, the compaction forces applied to the column, and the liquid superficial velocity. The chip beds were compressible and inelastic. Previous work from the literature using the Ergun equation to characterize pressure losses through chip beds is examined and compared with results of this work.
Décantation assistée par ultrasons des eaux résiduaires
Authors: Augis Nicolas , Hus Philippe , Thivel Pierre‐Xavier , Viau Jean‐Yves
Published: July 2010

Cette étude consiste à mettre en évidence l'impact des ultrasons sur le traitement des eaux par décantation. Elle a permis d'une part, d'identifier les effets déjà mesurés des ultrasons sur les propriétés de décantabilité de différents effluents et d'autre part, d'observer ces effets lors d'une étude statique puis dynamique. Des conditions de sonification favorables à l'optimisation d'un tel procédé ont été déterminées. Les résultats mettent en évidence le rôle fondamental joué par les systèmes d'ondes stationnaires dans l'amélioration de la décantabilité des effluents (floculés ou non, de synthèse ou réels). Dans le cas d'effluents floculés, un impact réel sur la décantation est visible.
A Novel Predictive Technique for Estimating the Hydrate Inhibition Effects of Single and Mixed Thermodynamic Inhibitors
Authors: Mohammadi Amir H. , Tohidi Bahman
Published: July 2010

A new correlation has been developed for predicting hydrate inhibition characteristics, as well as water freezing point depression of aqueous solutions containing salts and/or organic inhibitors. The correlation has been developed using hydrate inhibition/freezing point depression data at different concentrations of salt and/or organic inhibitor generated using a previously reported thermodynamic model. Independent data have been used in examining the reliability of this method. The predictions of this correlation are in acceptable agreement with the independent experimental data, demonstrating the reliability of this predictive technique for estimating the hydrate inhibition effects of salts and/or organic inhibitors.
Phase Equilibria for Ternary Liquid Systems of (Water + Carboxylic Acid + 1‐Heptanol) at 293.15 K: Modelling Considerations
Authors: Senol Aynur
Published: July 2010

Liquid‐liquid equilibrium data of the solubility curves and tie‐line end compositions are presented for mixtures of [water (1) + formic acid, or acetic acid, or propanoic acid (2) + 1‐heptanol (3)] at T = 293.15 K and P = (101.3 ± 0.7) kPa. The properties and liquid‐liquid equilibria (LLE) of associated ternary systems have been correlated using a solvatochromic approach SERLAS. The tie‐lines were also predicted using the UNIFAC‐original model. The proposed model appears to be an improvement in data fit for the ternary systems yielding a mean error of 3.8% for all the systems considered.
Dry‐Reforming of Ethanol in the Presence of a 316 Stainless Steel Catalyst
Authors: De Oliveira‐Vigier K. , Abatzoglou N. , Gitzhofer F.
Published: July 2010

Dry‐reforming is a known process for the production of synthetic gas from natural gas or other volatile fossil fuels. Another possible application is the reforming of hydrocarbons contained in the synthetic gas produced from biomass or waste gasification. The absence of wide industrial process applications is mainly due to the high endothermicity of the reactions involved and technical problems associated with carbon formation. In this work, the target reaction is:

The principal challenge is that of using a 2D catalyst formulation favouring the target reaction and permitting easy retrieval of deposited carbon while, at the same time, preserving the catalyst's activity and structural integrity.

This paper presents the results obtained from the use of a 316 stainless steel catalyst. The catalyst is active in ethanol dry reforming as the yield of hydrogen reached 98% of the theoretical value. Moreover, the co‐product carbon is of a filamentous form and can be easily retrieved without risk of modification to the catalyst properties. This catalyst is recyclable; it can be used several times over in the dry‐reforming of ethanol process without detectable change in its activity and selectivity.
Analytic Expressions of Ultimate Gains and Ultimate Periods with Phase‐Optimal Approximations of Time Delays
Authors: Lee Jietae , Park Ho Cheol , Sung Su Whan
Published: July 2010

Ultimate gains and ultimate periods have long been used to tune PI/PID controllers since the Ziegler‐Nichols tuning. Recently, very simple analytic equations for ultimate gains and ultimate periods by approximating the arctangent function have been presented, which can be used to obtain simple tuning rules. Here, by applying the Routh stability method and phase‐optimal approximations of the time delay term, we present analytic expressions of ultimate parameters that are as simple as the existing ones, showing better accuracy.
Three‐Dimensional CFD Simulation of Stratified Two‐Fluid Taylor‐Couette Flow
Authors: Vedantam Sreepriya , Joshi Jyeshtharaj B. , Koganti Sudhir B.
Published: July 2010

Two‐fluid Taylor‐Couette flow, with either one or both of the co‐axial cylinders rotating, has potential advantages over the conventional process equipment in chemical and bio‐process industries. This flow has been investigated using three‐dimensional CFD simulations. The occurrence of radial stratification, the subsequent onset of centrifugal instability in each phase, the cell formation and the dependency on various parameters have been analyzed and discussed. The criteria for the stratification, Taylor cell formation in each phase have been established. It can be stated that the analysis of single‐phase flow acts as the base state for the understanding of radial stratification of the two‐fluid flows. The extent of interface deformation also has been discussed. A complete energy balance has been established and a very good agreement was found between dissipation rate by CFD predictions and the energy input rate through the cylinder/s rotation.
Mass Transfer and Bioremediation of Naphthalene and Methyl Naphthalenes in Baffled and Bead Mill Bioreactors
Authors: Yu Ruihong , Nemati Mehdi , Hill Gordon , Headley John
Published: July 2010

Mass transfer and bioremediation of naphthalene, 2‐methylnaphthalene and 1,5‐dimethylnaphthalene have been studied in a rotating bioreactor modified with the addition of baffles and beads. Mass transfer rates of these low solubility organic particles dissolving in water (based on the working volume of the bioreactor) were highest in the bioreactor that combined beads and baffles, with the overall mass transfer coefficient (KLa) reaching up to 25 h−1. Based on its capacity to hold the largest volume of polluted media, the simple baffled bioreactor was considered to be the optimum roller bioreactor design. Using Pseudomonas putida, the bioremediation rate of naphthalene reached 61 mg/l‐h in this vessel and using mixed substrates, the bioremediation rate of 2‐methylnaphthalene reached 30 mg/l‐h. The dissolution rates for hydrophobic particles into the culture media during the bioremediation process were up to four times higher compared to mass transfer rates into abiotic controls, which was likely due to the production of biosurfactants by P. putida.
Steady Flow of Power Law Fluids across a Circular Cylinder
Authors: Bharti Ram Prakash , Chhabra R. P. , Eswaran V.
Published: July 2010

The momentum equations describing the steady cross‐flow of power law fluids past an unconfined circular cylinder have been solved numerically using a semi‐implicit finite volume method. The numerical results highlighting the roles of Reynolds number and power law index on the global and detailed flow characteristics have been presented over wide ranges of conditions as 5 ≤ Re ≤ 40 and 0.6 ≤ n ≤ 2. The shear‐thinning behaviour (n < 1) of the fluid decreases the size of recirculation zone and also delays the separation; on the other hand, the shear‐thickening fluids (n > 1) show the opposite behaviour. Furthermore, while the wake size shows non‐monotonous variation with the power law index, but it does not seem to influence the values of drag coefficient. The stagnation pressure coefficient and drag coefficient also show a complex dependence on the power law index and Reynolds number. In addition, the pressure coefficient, vorticity and viscosity distributions on the surface of the cylinder have also been presented to gain further physical insights into the detailed flow kinematics.
A Quantitative Measure to Evaluate Competing Designs for Non‐linear Dynamic Process Identification
Authors: Rollins Derrick K. , Pacheco Liza , Bhandari Nidhi , Nguyen Justin
Published: July 2010

The strategy for the collection of information (i.e., data) for model development is called experimental design. Optimal design seeks to maximize the information content under constraints of time and sampling. In the system identification literature the dominant strategy has been the method of pseudo random sequences (PRS). However, this work demonstrates that statistical design of experiments (SDOE) can provide greater information content as quantitatively measured by the D‐optimal criterion.
A Mortality Model for Penicillium bilaiae Subjected to Convective Air Drying
Authors: Friesen T. , Hill G. , Pugsley T. , Holloway G.
Published: July 2010

Drying of microbial cells for storage purposes is a widely practised technology. A new statistical model is proposed for survivability of microbial cells during convective air drying, where mortality is predicted by hazard functions and acceleration factors applied to temperature, moisture content and drying rate variables. The model is based on experimental survivability data generated from drying Penicillium bilaiae conidia at temperatures from 20 to 60°C and air relative humidities from 3 to 75%. Experimental data using “one at a time” variable manipulation was used to obtain five model parameters. Despite several simplifications to reduce the number of variable cross‐dependencies, the model was successfully validated using combined stress trials with maximum deviations of ±15%.
Biosorption of Phenol onto Posidonia oceanica (L.) Seagrass in Batch System: Equilibrium and Kinetic Modelling
Authors: Ncibi Mohamed Chaker , Mahjoub Borhane , Seffen Mongi
Published: July 2010

In this research, the biosorption of phenol using the fibres of a Mediterranean seagrass Posidonia oceanica (L.) was studied. Batch experimental procedures were made to investigate the ability of this novel marine biomass to remove phenol from aqueous phase. The influences of pH and contact time at different initial concentrations were evaluated. The results showed that biosorption capacity was enhanced using solution pH equal to 5.2. The modelling results showed that pseudo‐second‐order and Redlich‐Peterson models were found to be the most suitable to satisfactory describe the kinetic and equilibrium adsorption data, respectively.