bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Minimum Fluidization Velocity in Two and Three Phase Inverse Fluidized Beds
Authors: Renganathan Thiruvengadam , Krishnaiah Kamatam
Published: July 2010

Generalized equations for predicting minimum fluidization velocities in two‐phase L‐S and three‐phase G‐L‐S inverse fluidized bed are developed covering a wide range of variables using the experimental data obtained from the present work and that available in the literature. It is found that the classical Wen and Yu equation for predicting minimum fluidization velocity can satisfactorily be used for two‐phase inverse fluidized bed. A model based on empiricism and another based on the gas perturbed liquid model, which reduce to limiting conditions such as liquid solid and three‐phase batch liquid systems are proposed.
CO2 Mineral Sequestration: Chemically Enhanced Aqueous Carbonation of Serpentine
Authors: Park Ah‐Hyung Alissa , Jadhav Raja , Fan Liang‐Shih
Published: July 2010

As one of the greenhouse gases, it is essential to reduce CO2 emissions in order to stabilize CO2 levels in the atmosphere while allowing the continued use of fossil fuels. Abatement of CO2 by mineral carbonation has been proposed as one of the most promising methods for CO2 emission control in the flue gas from coal‐fired power plants. However, little is known about the fundamental characteristics of CO2‐mineral reactions. The overall goal of this study was to investigate the mechanisms of the aqueous reactions of CO2 with Mg‐bearing minerals. Specifically, the focus was on the enhancement of the mineral dissolution.
Modeling the Injection of Gas‐Liquid Jets into Fluidized Beds of Fine Particles
Authors: Ariyapadi Siva , Berruti Franco , Briens Cedric , Griffith Peter , Hulet Craig
Published: July 2010

Contacting of gas‐liquid jets with particles/ catalyst is essential in many fluidization processes. This paper discusses a momentum conservation model to determine the entrainment rate of solids and gas into a gas‐liquid jet, injected in a fluidized bed. A novel experimental technique developed by Felli (2002) is used to verify the model results. Correction factors to the initial momentum calculated from the homogenous model are addressed. The model predictions are in good agreement with the experimental data. The present model can be used to characterize the behaviour of gas‐liquid jets (fine sprays) injected into fluidized beds of fine particles.
Instability due to Viscosity Stratification Downstream of a Centerline Injector
Authors: Cao Qing , Ventresca Amy L. , Sreenivas K. R. , Prasad Ajay K.
Published: July 2010

A common injector geometry upstream of a static mixer is the centerline injector. A flow instability can arise due to viscosity differences between the injected core‐flow and the outer co‐flow. This instability can adversely affect the effectiveness of the mixing operation. An experimental investigation of miscible viscosity‐stratified flow in a circular geometry was performed using Laser Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV). The experimental results for the stable region agree with the analytical results. The unstable region exhibits different modes depending on the viscosity ratio, volume flux ratio, and Reynolds number. The modes include wavy core‐flow with fissures and wavy core‐flow with core breakup. The time‐averaged experiment velocity profiles for the unstable core indicate a broadening of the jet at the centerline, which is consistent with the LIF visualization.
Spray Characteristics of Two‐phase Feed Nozzles
Authors: Ariyapadi Siva , Balachandar Ram , Berruti Franco
Published: July 2010

The present study focuses on understanding the spray characteristics of a turbulent gas‐liquid jet (Reliq = 24,000). Air and water are used as the test fluids. The angles of injection of the two phases upstream of the nozzle are varied (θ = 20°, 45° and 90°) and the effect of carrier gas on the droplet characteristics is are also investigated. The droplet size and velocity are non‐intrusively measured using a Phase‐Doppler Particle Analyzer (PDPA). In some respects, the characteristics of the present two‐phase jet are similar to those noticed in previous studies, while revealing some important differences. The centreline mean droplet velocities (15 ∼ 20 m/s) increase in the initial region of the jet, attain a maximum and then decrease at larger distances from the nozzle exit. Most of the entrainment occurs at the tip of the nozzle and the jet expansion rate decreases significantly at distances where the spray velocity profiles become self‐similar. A Lorentz‐type fit has been used to model the normalized radial velocity profiles. The results indicate that the test configuration with θ = 45° may be beneficial for the scenario discussed.
Hydrodynamic Model for Horizontal Two‐phase Flow Through Porous Media
Authors: Iliuta Ion , Fourar Mostafa , Larachi Faïçal
Published: July 2010

A unidirectional, two‐fluid model based on the volume‐average mass and momentum balance equations was developed for the prediction of two‐phase pressure drop and external liquid hold‐up in horizontally positioned packed beds experiencing stratified, annular and dispersed bubble flow regimes. The so‐called slit model drag force closures were used for the stratified and annular flow regimes. In the case of dispersed bubble flow regime, the liquid‐solid interaction force was formulated on the basis of the Kozeny‐Carman equation by taking into account the presence of bubbles in reducing the available volume for the flowing liquid. The gas‐liquid interaction force was evaluated by using the respective solutions of drag coefficient for an isolated bubble in viscous and turbulent flows. The proposed drag force expressions for the different flow patterns occurring in the bed associated with the two‐fluid model resulted in a predictive method requiring no adjustable parameter to describe the hydrodynamics for horizontal two‐phase flow in packed beds.
Further Understanding of the Chemistry of Manganese‐Induced Peroxide Decomposition
Authors: Wekesa Moses , Ni Yonghao
Published: July 2010

Manganese is the most effective catalyst for the hydrogen peroxide decomposition during peroxide bleaching used in the pulp and paper industry. We studied the chemistry involved in this project. The results showed that Mn2+ and Mn3+ are present during the course of the reaction. We followed the Mn2+ and Mn3+ concentrations during the course. It was found that a steady state of Mn3+ concentration was attained until the hydrogen peroxide concentration was zero. At this time, the Mn3+ concentration was maximum, then it decreased due to the disproportionation to form MnO2. Removal of O2 from the system slowed down the rate of decomposition. The detailed reactions involved were discussed.
Spiral Wound Reverse Osmosis Modules Decomposition into Elementary Units by Analyzing Stimulus Response Experiments: Characterization of the Solute Transfer across the Membrane
Authors: Roth Estelle , Fabre Bernard , Accary Armand
Published: July 2010

A model for spiral wound reverse osmosis modules FT30‐4040 has been developed by analyzing stimulus response experiments. Perfect mixing cells represent edthe flow and dispersed plug flow represented the membrane. The model was based on phenomenological equations describing the permeation. The identification of the Peclet number and the space‐time characterizing each dispersed plug flow led to the estimation of the tracer dispersion coefficient in the membrane. Ones new and two used composite reverse osmosis modules were tested. The decrease of the rejection properties of the used membranes was linked to the apparition of new plug flows with high dispersion coefficients within the membrane.
A Rheological Model for the Interface of Immiscible Polymer Melt in Blending Process
Authors: Zhou Chixing , Yu Wei
Published: July 2010

We used an area density tensor as an interface variable of immiscible polymer blend. A phenomenological model for the evolution of such area density tensor in flow fields was established based on the concept of non‐equilibrium thermodynamics of complex polymeric fluids, without the limitations of passive mixing. Phase deformation, break up, relaxation, coalescence effect, as well as non‐affine deformation of the dispersed phase with matrix are all considered in the model. The model predictions show that interfacial slip greatly affects the morphology evolution. The influences of other factors, such as volume fraction, shear rate, interfacial tension, and viscosity ratio, on interfacial area development are also discussed.
Flow Characterization of a Three‐Phase Circulating Fluidized Bed Using an Ultrasonic Technique
Authors: Vatanakull Maytinee , Zheng Ying , Couturier Michel
Published: July 2010

The axial and radial distributions of solid and gas holdups were investigated in an air‐water‐glass bead circulating fluidized bed (GLSCFB) using a new ultrasonic technique, with a new method based on signal fluctuations. The cross‐sectional averaged gas and solid holdups measured at two axial positions appear to be similar at all studied operating conditions. The radial non‐uniformity decreases with increasing liquid velocity but does not change with an increasing solid circulating rate. The radial distribution of gas holdup was more uniform for 1.3 mm beads than for 433 µm glass beads.
Measurement of Turbulent Mixing in a Confined Wake Flow Using Combined PIV and PLIF
Authors: Hjertager Lene K. , Hjertager Bjørn H. , Deen Niels G. , Solberg Tron
Published: July 2010

Turbulent mixing in a confined wake flow was studied by using the combined PIV/PLIF technique to measure instantaneous concentration and velocity fields. Measurements were performed at two slightly overlapping areas in the initial mixing zone and at an area at the end of the channel. The measurements revealed that there is a recirculation zone right behind the block that gives an increased mixing effect in this area. The measurement at the end of the channel shows that the concentration distribution is quite uniform, but the two streams are not completely mixed.
Amplification of Periodic Temperature Disturbances in a Packed‐Bed Reactor: CO Oxidation over a CuO/Al2O3 Catalyst
Authors: Na‐Ranong Duangkamol , Jaree Attasak , Hudgins Robert R. , Budman Hector M. , Silveston Peter L. , Menzinger Michael
Published: July 2010

Amplification of periodic variations of input temperature in a product‐inhibited reaction — CO oxidation over CuO‐γ‐Al2O3 — was investigated experimentally in an insulated packed‐bed reactor. At steady state the temperature profile was elongated compared with that of a reactant‐inhibited CO oxidation over Pt/Al2O3, studied elsewhere. Under periodic operation, amplitudes of the resulting travelling temperature waves, monitored downstream from the reaction front, were amplified to a greater extent than those in the reactant‐inhibited CO oxidation over Pt/Al2O3. The magnitude of the amplification depended on the perturbation frequency and showed resonance behaviour. The magnitude decreased monotonically with increasing perturbation amplitude.
Experimental Study of Influence of the Impeller Spacing on Flow Behaviour of Double‐Impeller Stirred Tank
Authors: Xueming Shao , Xiaoling Liu , Yulin Li
Published: July 2010

The flow fields in the stirred tank with three different kinds of combined double‐impeller agitators: disc turbine + disc turbine (DT‐DT, radial impeller), pitched blade turbine + pitched blade turbine (PTD‐PTD, axial impeller) and pitched blade turbine + disc turbine (PTD‐DT), were investigated in detail by using laser Doppler anemometry. The two‐dimensional mean velocity field and the distribution of turbulence intensity were obtained for different impeller spacings. The experimental results show that the impeller spacing has a significant influence on the flow field. To improve flow homogeneity and agitator efficiency, the appropriate impeller spacing should be in the range of 1/2 to 2/3 of the tank diameter.
Numerical Simulations of the Effect of Conical Dimension on the Hydrodynamic Behaviour in Spouted Beds
Authors: Yurong He , Guangbo Zhao , Bouillard Jacques , Huilin Lu
Published: July 2010

The flow behaviours of gas‐solids were predicted by means of a hydrodynamic model of dense gas‐solid flow in spouted beds. Constitutive equations describing the particulate solids pressure and viscosity were implemented into a hydrodynamic simulation computer program. The effect of operating conditions (inclined angle and gas spouting velocity) on particle velocity and concentration in the spout, annulus and fountain regions were numerical studied. Both vertical and horizontal particle velocities increased with increasing spouting gas velocity. The diameter of the spout increases with decreasing the inclination angle. As the inclination angle is set greater than 60°, the spout cross‐section starts becoming bottlenecked, limiting the upwards flow of solids.
Removal of SO2 in Semi‐Dry Flue Gas Desulfurization Process with a Powder‐Particle Spouted Bed
Authors: Nakazato Tsutomu , Liu Yunyi , Kato Kunio
Published: July 2010

Semi‐dry flue gas desulfurization was investigated with several kinds of SO2 sorbents, such as slaked lime, limestone, Mg(OH)2 and concrete pile sludge, in a powder‐particle spouted bed. Slurry droplets including sorbent fine particles were fed to a spouted bed of coarse inert particles spouted with hot gas containing SO2. SO2 removal efficiency was strongly affected by the approach to saturation temperature, Ca/S molar ratio and particle size of sorbent. Slaked lime showed the highest desulfurization efficiency. In this process, despite very short gas residence time, more than 90% SO2 removal was easily achieved by choosing appropriate conditions.
The Use of a Population Balance Model in the Study of Inoculation of Soybean Seeds in a Spouted Bed
Authors: Duarte Claudio R. , Murata Valéria V. , Barrozo A. S.
Published: July 2010

The coating of soybean seeds with bacteria and micronutrients favours the vigorous growth of the plant, dispensing with the use of ammoniacal fertilizers. The optimum thickness of the coating should allow the fundamental gaseous interchanges for the germination and the ideal conditions for the activity of the bacteria. The objective of this work was to simulate dynamic mass distribution of soybean seeds covered with bacteria and macronutrients in spouted bed through a specific program developed in Maple V®. The validation of the model is done through 16 experiments carried out in a spouted bed with spray at the top.
Effect of the Equipment Configuration and Operating Conditions on Process Performance and on Physical Characteristics of the Product During Coating in Spouted Bed
Authors: Publio M. C. P. , Oliveira W. P.
Published: July 2010

The effects of the configuration and operating conditions on the performance of the spouted bed tablet coating process have been studied. The configuration parameters analyzed were the ratio between the draft tube diameter and the inlet orifice diameter, dT/di, and the conical base angle, γ. To analyze the equipment performance the adhesion coefficient, η, and the increase rate of the tablet mass, K1, were measured as a function of the mass flow rate of the coating material, Ws, of the ratio between the mass feed flow rate of coating suspension relative to mass feed flow rate of the spouting gas, W*s/W*g, of the air flow rate relative to minimum spouting, Q/Qms, and of the feed flow rate of atomising air, Wat. Procedures for the evaluation of the growth kinetics and for measuring the product uniformity are presented.
Drying of Liquid Feedstocks in a Spout‐Fluid‐Bed with Draft‐Tube Submerged in Inert Solids: Hydrodynamics and Drying Performance
Authors: Osorio‐Revilla G , Elías‐Serrano R , Gallardo‐Velázquez T
Published: July 2010

A spout‐fluid bed with draft tube submerged in a bed of polypropylene beads was used for drying maltodextrin solutions. The hydrodynamics of the dryer were studied by determining the annular air flow vertical profile at different spouting velocities, using an additional air flow rate through the annulus equivalent to 0.5 Umf. The drying performance of the dryer was studied through the determination of several dryer response parameters (product moisture, evaporative capacity and volumetric evaporative capacity). These parameters were compared with those obtained in a conventional spouted bed with inert solids and a spray dryer.
Analysis and Interpretation of Multiple Radioactive Particle Tracking Data on Laboratory Scale Air/Polyethylene Fluidized Beds
Authors: Schober Loni , Kantzas Apostolos
Published: July 2010

Multiple radioactive particle tracking is a noninvasive technique used to study flow phenomena within gas‐solid fluidized beds. Five tagged polyethylene particles were added to a fluidized bed and tracked using two gamma cameras set perpendicular to one another. One camera collected x‐z particle locations and the other collected y‐z particle locations, while both cameras collected particle count rate values. The x‐z and y‐z particle movement information was combined to form three‐dimensional particle trajectories, and in turn used to calculate instantaneous flow information. The information from the five particles was then averaged and used to calculate three‐dimensional information regarding solid circulation parameters.
Pressure Fluctuation Analysis of Laboratory Scale Air/Polyethylene Fluidized Beds
Authors: Schober Loni , Kantzas Apostolos , Hugo Ron
Published: July 2010

Differential pressure fluctuations were studied along the wall of a laboratory scale column filled with a polyethylene resin. Air flow rates to the column were varied in order to examine the changes in wall pressure with respect to superficial gas velocity. Statistical and spectral analysis was used to study the periodic features of column wall pressure measurements in the dense region of a fluidized bed. From the analysis, it is evident that multiple flow regimes exist in the column. These flow regimes are dependent upon the height above the distributor. Results also show a significant peak developing at 1 Hz as superficial gas velocity increases.
Factors Affecting Stable Operation of Counter‐current Multistage Fluidized Bed of Solid‐liquid System — Dimensions of Downspout
Authors: Tokuyama Hideaki , Natsume Masayuki , Nii Susumu , Kawaizumi Fumio , Takahashi Katsuroku
Published: July 2010

For the effective use of an ion exchange resin, a counter‐current multistage fluidized bed has been developed. An appropriate design of the downspout, which works to let particles flow down to next stage, is essential to obtain a stable resin flow. From an experimental study on the particle holdup and pressure drop in the multistage fluidized bed, a method to determine the downspout size has been developed. The relation between the liquid velocity within the downspout and the superficial liquid velocity has been derived from considering the pressure balance between the part of the fluidized bed and that of the downspout.
Emulsion Analysis in a Gas/Liquid/Liquid Reactor With Top Blowing
Authors: Martín Margarita , Rendueles Manuel , Díaz Mario
Published: July 2010

Top blowing is a common operation in metallurgical oxidation processes such as those found in steel production. One advantage of this kind of blowing is the absence of any submerged element in the melt. The analysis of fluidynamics and mass transfer usually requires the employment of cold models. Thus, a GLL' cold model of a steel converter was accordingly designed that illustrated the presence of emulsions likewise reported in real reactors. The characteristics of this system were studied, namely the kinetics of emulsion formation and destruction. A model was subsequently elaborated for the stages of emulsion formation and destruction.
Reverse Micellar Extraction of Lysozyme Using Two Dialkyl Sodium Phosphinates
Authors: Shin Youn‐Ok , Vera Juan H.
Published: July 2010

The extraction of lysozyme was studied using di‐(2,4,4‐trimethylpentyl) sodium phosphinate, R2POONa, and di‐(2,4,4‐trimethylpentyl) sodium dithiophosphinate, R2PSSNa. For a R2POONa reverse micellar system, all lysozyme was removed from the aqueous phase when the pH of the aqueous solution was set below the pI of the protein. The extraction of lysozyme into a R2PSSNa reverse micellar system was independent of the pH of the aqueous phase. A solubilization limit of lysozyme exists in the R2POONa reverse micellar phase. The lysozyme recovery was 70% from the R2POONa reverse micellar phase, and less than 10% from the R2PSSNa reverse micellar phase.
A Laboratory Reactor for Gas‐Phase Olefin Polymerization
Authors: Mannan Tariq M. , Hammawa Hassan , Lynch David T. , Wanke Sieghard E.
Published: July 2010

A new reactor system for gas‐phase ethylene/α‐olefin polymerization is described. Good gas‐phase temperature control at high polymerization rates was achieved with the 2‐L semi‐batch reactor. Ethylene/1‐hexene and ethylene polymerization results showing the effects of operating conditions on temperature profiles are presented. Good gas‐phase temperature control is required to obtain reliable activity profiles. A gas‐sampling and analysis system, which allows relatively rapid (< 3 min) and accurate determination of ethylene/1‐hexene contents in the gas‐phase of the reactor, is also described. Rapid and reliable hydrogen contents were also measured with this relatively inexpensive system.
A Model for Residence Time Distribution of Solids in a Rotary Kiln
Authors: Dinesh V Loni , Sai P. S. T.
Published: July 2010

A five‐parameter model for residence time distribution of low‐density particles in a bed of high‐density particles in a rotary kiln is derived based on combinations of flow regimes in several sub‐regions. The parameters of the model are the number of turnover stages, the cascade volume fraction, the Peclet number, the dead volume fraction in cascade region, and the cross‐flow ratio. The effect of feed rate of solids, rotational speed and inclination of the kiln on the model parameters is evaluated.
Development of a Continuous High‐Efficiency Laboratory Fibre Fractionator
Authors: Young Edmond , Olson James A.
Published: July 2010

This study proposes to develop a continuous, high‐efficiency laboratory fibre fractionator capable of producing large quantities of well‐fractionated fibres. The concept requires modifying a conventional Bauer‐McNett classifier to include feedback and continuous feed flows. A computer model of the proposed fractionator was first constructed using Simulink in MATLAB. Simulations were performed to study effects of six system parameters on two fractionation characteristics. Results indicated that while large screen apertures led to higher cut‐off length, they also resulted in less distinct separation. Simulations were validated with experimental tests performed on a prototype fractionator. Excellent agreement was found between experiment and simulation.
Bubble Formation at a Rotating Cylindrical Surface in Cross‐Flowing Liquid
Authors: Machniewski Piotr M. , Biń Andrzej K. , Evans Geoffrey M.
Published: July 2010

A novel method of gas sparging from a rotating cylinder is proposed, which prevents against formation of large attached gas cavities in cross‐flowing liquids including those flowing downwards. Experimental and theoretical results regarding critical rotation speed necessary to remove the attached cavity, bubble formation process and size distribution of the produced bubbles in a low viscosity system (air‐water) are presented in this study.
Gas‐Liquid Mass Transfer in Pulp Retention Towers
Authors: Rewatkar Vilas B. , Bennington Chad P. J.
Published: July 2010

The volumetric gas‐liquid mass transfer rate, kLa, was measured under batch conditions in a 0.28 m diameter laboratory‐scale retention column. Tests on water, and on unbleached kraft (UBK) pulp suspensions (mass fractions, Cm from 0.013 to 0.09) were made with air or nitrogen sparged through the column at superficial gas velocities between 0.0015 to 0.05 m/s. kLa varied with suspension mass concentration and superficial gas velocity, initially decreasing with increasing mass concentration, reaching a minimum between Cm = 0.03 and 0.06, and then increasing. The minimum in kLa coincided with a change in hydrodynamics within the column, from bubble column behaviour below Cm = 0.03 to porous solid behaviour above Cm = 0.06.
Continuous Toluene Vapor Remediation in a Well‐Mixed Bioreactor
Authors: Bi Yonghong , Hill Gordon A. , Sumner Robert J.
Published: July 2010

Mass transfer and bioremediation of toluene from a contaminated air stream has been investigated using a continuous flow, stirred tank bioreactor. The toluene mass transfer coefficients varied from 3.1 to 3.8 h−1 as the agitation speed increased from 300 to 600 rpm. Using a pure culture, toluene could not be continuously bioremediated as a sole substrate. When ethanol was used as a cosubstrate, toluene was continuously captured and bioremediated at rates up to 90 mg/L·h with removal efficiencies up to 90%, while ethanol was simultaneously degraded at rates up to 250 mg/L·h. Using benzyl alcohol as the cosubstrate, toluene removal efficiencies were above 97% at continuous loading rates of 90 mg/L·h and benzyl alcohol loading rates up to 300 mg/L·h.
Effect of Inlet Type on Shear Stress and Mixing in an Annular Photobioreactor Involving a Swirling Decaying Flow
Authors: Pruvost Jérémy , Legrand Jack , Legentilhomme Patrick , Muller‐Feuga Arnaud
Published: July 2010

Improvement of mixing can lead to an enhancement of photobioreactors productivity, provided that the adverse effect of shear forces is kept below the fragility‐ threshold of cells. Implementation of a swirling decaying flow induced by a tangential inlet in an annular photobioreactor was investigated. The study focused on a compromise solution between the mixing and the resulting shear stress, and various hydrodynamical characteristics were measured for five types of tangential inlets and three Reynolds number values. Comparison with a pseudo‐axial flow induced by a radial inlet indicates that swirling flows are suitable in the particular application of microalgal cultures.
Study of Tire Particle Mixing in a Moving and Stirred Bed Vacuum Pyrolysis Reactor
Authors: Yang Jin , Gupta Murlidhar , Roy Xavier , Roy Christian
Published: July 2010

The paper studies the motion of scrap tire shreds in a moving and stirred bed vacuum pyrolysis reactor. The reactor configuration is a novel concept. The pattern and the residence time distribution (RTD) of the particle motion in the reactor were investigated using tracers, for different feed rates and blade speeds. It was shown that the particle motion in the reactor is plug flow nature with intermediate dispersion (σ2 = 0.02—0.055). The mean residence time is in the range of 7—23 min, depending on the speed of the blades and the feed rate. The ratio of mean particle speed and the speed of blades vm/vb varied between 0.03 and 0.07.
Separation and Characterisation of Problematic Solids from Athabasca Oil Sands and Waste Unit Samples
Authors: Tu Yun , Li Zaifeng , Pleizier Gerry , Ng Samson , Chung Keng H.
Published: July 2010

Traditionally, Athabasca oil sands have been classified by bitumen and fines (<44 µm) contents. However, these markers do not always identify ores with poor processing characteristics. Consequently, there is a need to discover other characteristics to define problem ores. Here we describe a separation scheme for oil sands solids fractions based on their physical and surface properties. Clay material (<3 µm) and its ultra‐fine (<0.3 µm) component are of particular interest. Settling tests on ultra‐fine clay suspensions confirm that this fraction is the major cause of sludging during primary bitumen separation. Waste units, or barren oil sands, are shown to be a major source of this component.
Assessment of Bitumen Re c overy from the Athabasca Oil Sands Using a Laboratory Denver Flotation Cell
Authors: Zhou Z , Kasongo T , Xu Z , Masliyah J
Published: July 2010

A methodology was developed in this study to evaluate the effect of operating parameters on the processability of oil sands using small‐scale laboratory experimental devices. By subtracting bitumen recovered to the froth by entrainment with water, the concept of “true flotation recovery” is proposed to describe bitumen recovery resulting from bitumenbubble attachment. The experimental results indicated that “true flotation recovery” is a more sensitive and meaningful marker than overall bitumen recovery to evaluate the processability of oil sands using small‐scale laboratory test units.
Factors Governing Friction Losses in Self‐lubricated Transport of Bitumen Froth: 1. Water Release
Authors: Sanders R Sean , Ko Taehwan , Bai Runyuan , Joseph Daniel D.
Published: July 2010

Syncrude Canada Ltd. transports bitumen froth, a viscous intermediate product of the oil sand extraction process, 35 km via pipeline. Pipeline transport is feasible because some of the water that occurs naturally in the froth forms a thin lubricating layer around a bitumen‐rich core, thereby greatly reducing friction losses and transportation costs. In this paper, the effect of froth composition (namely, water content) on the formation of the lubricating layer is reported. Tests were conducted with a 25 mm diameter pipe loop and a concentric cylinder froth rheometer. Measurements of pressure gradient and water holdup (free water fraction), along with visual observations, showed that froth containing a lower total water content yielded less free water to the lubricating layer. In the froth rheometer, the conditions for which stable, self‐lubricated flow could be maintained were comparable to those required to maintain self‐lubricated flow in the 25 mm pipe loop.
Monte Carlo Simulation of Coalescence Processes in Oil Sands Slurries
Authors: Friesen Waldemar I. , Dabros Tadeusz
Published: July 2010

Conditioning of an oil sand slurry is a critical step in the extraction of bitumen from oil sand ore. To model the conditioning process, a constant‐number Monte Carlo algorithm is used to simulate the mean‐field kinetics of coalescing bitumen drops and air bubbles. The coalescence rate of drops and bubbles is described by the model of Coulaloglou and Tavlarides (1977). Simulations yield results that are consistent with aerated bitumen drop sizes and conditioning times reported in the literature. The effects of turbulent energy, bitumen concentration, and initial bitumen drop size on the evolution of drop size distributions are investigated.
Rate of Bitumen Film Transfer from a Quartz Surface to an Air Bubble as Observed by Optical Microscopy
Authors: Lelinski Dariusz , Drelich Jaroslaw , Miller Jan D. , Hupka Jan
Published: July 2010

The rate of bitumen transfer from a bitumen‐coated quartz plate to a gas bubble surface in aqueous alkaline solutions was recorded photographically. During bitumen spreading, a bulk layer followed the formation of thin bitumen films (precursor films). The bulk layer spread at the bubble surface with a velocity of about one order of magnitude less than the velocity of the precursor film. The energy of activation for spreading of the bulk layer varied from about 66 to 123 kJ/mol depending on the stage of bitumen spreading but remained constant at about 105 kJ/mol for the precursor film. Results are discussed with respect to fundamental issues associated with flotation recovery of heavy oils.
Breaking Water‐in‐Bitumen Emulsions using Polyoxyalkylated DETA Demulsifier
Authors: Xu Yuming , Wu Jiangying , Dabros Tadek , Hamza Hassan , Wang Sanyi , Bidal Marianne , Venter Johann , Tran Tom
Published: July 2010

Adding demulsifier is currently the most widely used method for breaking water‐in‐oil emulsions. Experimental demulsifiers based on DETA with various PO and EO contents were synthesized and their RSN values were determined. The dehydration efficiency of these demulsifiers was measured in diluted bitumen using both gravitational settling and centrifugation tests. The results indicate that some of the DETA products could perform potentially at least as well or better than the demulsifier currently used in a commercial plant. RSN values are correlated very well with EO and PO numbers. Optimal dehydration efficiency is in the RSN range of 18 to 22, which corresponds to a PO‐to‐EO ratio in the range of 1 to 1.8.
A Novel Approach for Resolving Reverse Emulsions in SAGD Production Systems
Authors: Bosch Ron , Axcell Eric , Little Virgil , Cleary Robert , Wang Sanyi , Gabel Robert , Moreland Bill
Published: July 2010

The standard method for water clarification in SAGD operations involved the injection of latex polymers to break produced reverse emulsions. Operationally, this resulted in large quantities of oil in the water downstream of the first oil and water separation vessel. Problems occurred because this generated large amounts of oily solids and emulsion. This slop material represented a significant additional expenditure. Champion developed a novel approach to treat these systems and reduce slop. This program has been very successful in removing oil from the water stream during primary separation, thus reducing costs associated with reprocessing slop oil, and resulting in greater oil recovery.
The Conductivity and Dielectric Behavior of Solutions of Bitumen In Toluene
Authors: Chow Ross S. , Tse Daniel L. , Takamura Koichi
Published: July 2010

The conductivity and dielectric constant of solutions of bitumen in toluene were determined for bitumens of differing asphaltene content. The results show that the conductivity is primarily controlled by the asphaltene content while the dielectric constant can be described in terms of the polarity and concentration of the various fractions of the bitumen. It is demonstrated that it is possible to determine bitumen content of a solution of bitumen in toluene by measuring the conductivity.
Bubble Size Distributions for Dispersed Air – Water Flows in a 100 mm Horizontal Pipeline
Authors: Sanders R. Sean , Razzaque M. Mahbubur , Schaan Jason , Nandakumar K. , Masliyah Jacob H. , Afacan Artin , Liu Shijie
Published: July 2010

The bubble size distributions of air dispersed in water flowing in a 100 mm horizontal pipeline were studied. Size distributions were obtained with a high‐speed digital camera at axial positions 0.5, 15.3 and 42.3 m from the air injection point. Air was injected into the pipeline through a narrow tube extending into the pipe, perpendicular to the pipe axis. The effects of average water velocity, air concentration, and injection nozzle diameter on the evolution of bubble size distribution with axial pipe position were studied. For the lowest air concentration of 0.07%, equilibrium bubble size distributions were dependent only on water velocity. Nozzle injection diameter did not affect the downstream bubble size distributions at air concentrations of 0.07% and 0.3%. Levich's break‐up theory was found to over‐predict the experimental dmax for each test condition.
A Method for Calculation of Final Film Thickness in Free Coating of Viscoelastic Fluids onto a Vertical Surface
Authors: Savarmand Saeid , Azizmohammadi Siroos , Bahrami Ali , Golkar‐Narenji Mohammad‐Reza
Published: July 2010

A method for the calculation of the final film thickness in free coating of a viscoelastic fluid onto a vertical surface withdrawn from its vessel is developed. The method is based on the definition of an objective function, the minimization of which guarantees that the kinematic as well as the dynamic conditions at the lower boundary of the dynamic meniscus region are simultaneously satisfied. A systematic approach is provided in order to localize the optimum value of the final film thickness within the optimization interval. It was observed that there was a clear relationship between the estimated final film thickness and the value of a parameter A. The closeness of this parameter to zero corresponds to the dynamic constraint being fulfilled at the lower boundary of the dynamic meniscus region. This relationship is used as an objective means of determining the direction to update the interval of optimization to obtain the final thickness of the film. The results of the proposed method are compared to the previous works on the free coating of viscoelastic fluids, which are based on a trial‐and‐error method. The performance of the previously applied rheological models to the formulation of the free coating process, mainly the modified Oldroyd models, is also compared by introducing the present method.
Strategies for Starting Up Azeotropic Distillation Columns with Multiple Steady States
Authors: Benz Sonia J. , Francesconi Javier A. , Scenna Nicolás J.
Published: July 2010

The operability of azeotropic distillation columns with multiplicity is analysed during start‐up by dynamic simulation. Different steady states can be reached by applying different start‐up configurations and/or policies. The well‐known benzene‐heptane‐acetone (BHA) system is studied. The process by which the column reaches these steady states can be seen through the examination of profile evolutions corresponding to the given start‐up policies. Indeed, a clear partition of the start‐up policies space yielding different solutions is achieved. Some properties of this space are explained and start‐up critical values can be identified. Finally, some guidelines for start‐up supervision are outlined for the study case.
Kinetics and Combustion Characteristics of Deinking Sludge in a Thermobalance and an Internally Circulating Fluidized Bed
Authors: Namkung Won , Roh Seon A. H. , Guy Christophe , Kim Sang Done
Published: July 2010

The kinetic parameters (activation energy, pre‐exponential factor and reaction order) of volatile and char of deinking sludge are determined by thermo‐gravimetric analysis. From the Arrhenius plot, the activation energy and the pre‐exponential factor of char are determined. The reaction order is found to be 0.7 with respect to oxygen partial pressures of 507 – 3040 Pa. The effects of riser gas velocity, solid feeding rate and annulus air on combustion efficiency have been determined in an internally circulating fluidized bed (ICFB). The combustion efficiency decreases with increasing riser gas velocity and solid feeding rate, while it increases with increasing annulus air. High combustion efficiency is obtained when the annulus air is injected.
Simulation de la distillation catalytique par un nouveau modèle de transfert – Application à la production d'acétate de méthyle
Authors: Druart Florence , Reneaume Jean‐Michel , Meyer Michel , Rouzineau David
Published: July 2010

Nous présentons un modéle de transfert pour la distillation catalytique utilisant les équations de Maxwell‐Stefan et incluant la diffusion effective dans le catalyseur poreux. L'écriture et la résolution de ce modéle ont été adaptées à son inclusion dans un simulateur commercial. Il est donc robuste et souple. Nous étudions l'influence des caractéristiques du catalyseur, de la configuration de la colonne, de la non‐idéalité du mélange et de la qualité de l'échange liquide/vapeur. La conclusion principale de ces essais est l'existence d'un optimum de fonctionnement notamment pour le taux de reflux et l'emplacement du catalyseur.
A Modular Mixed‐Integer Non‐Linear Programming Algorithm for Synthesis of Chemical Processes
Authors: Li Hehua , Qian Yu , Zheng Shiqing , Cheng Huanong
Published: July 2010

A modular approach to the formulation and a solution of mixed‐integer non‐linear programming (MINLP) problems are presented, which reduce the size of MINLP and the computational expenses effectively. The method decomposes the synthesis task into three hierarchical levels—the superstructure, the structure, and the modules, with the layer of modules being the most critical to the problem solution. The strategy has been implemented in a simulation environment in which the variables of interest are defined as implicit functions of the optimization variables. The implicit relationships are handled using a data‐oriented process simulation technique (DOPS) that significantly simplify the simulation. The method has been effectively applied to two case studies, one from literature for the synthesis of hydrodesalkylation, and another from industrial process manufacturing methylene diphenylene diisocyanates.
Holdup Profile in Multistage Stirred‐Cell Liquid‐Liquid Extraction Column Using Population Balance Model
Authors: Ismail Ashraf S.
Published: July 2010

The drop exit frequency model developed in the literature is modified and simplified to suit the practical situations. An adjusting factor is inserted in the exit frequency model to account for the simplification of the hydrodynamic pattern used in the analysis and the incorrect constants used in the rise velocity model. The holdup profiles calculated in the present analysis are compared with experimental and theoretical results in the literature to evaluate the model. The comparison shows good agreement between the present model and the experimental data. Even for the cases of poor agreement, the breakage and coalescence rates are adjusted, and the stages of quasi‐equilibrium state are determined to improve the results.
The Bed Expansion and Particle Velocity Analysis in the Swirling Fluidized Bed Combustor (SFBC) Cold Model
Authors: Lee S. W. , Liu Y
Published: July 2010

Flow visualization and analysis was extensively conducted in a bench‐scale swirling fluidized bed combustor (SFBC) cold model. An advanced laser‐based particle image velocimetry (PIV) system was used to visualize the gas‐particle flow in SFBC cold model. The robust experiment design method was applied to study the bed expansion in the SFBC cold model in relationship with secondary airflow ratio. It was found that the secondary airflow ratio did not affect the bed expansion in the SFBC cold model. Based on the PIV velocity profiles analysis, it was observed that particle velocities increased when secondary airflow ratio is increased. The secondary air was definitely generating the high tangential particle velocity.
Power‐Law Fluid Flow Over a Sphere: Average Shear Rate and Drag Coefficient
Authors: Renaud Maurice , Mauret Evelyne , Chhabra Rajendra P.
Published: July 2010

Based on the consideration of the rate of mechanical energy dissipation, an expression for the average shear rate for a sphere falling in a power‐law fluid in the creeping flow regime has been deduced. The average shear rate in a power‐law fluid (n<1) appears to be higher than that in an equivalent Newtonian fluid. This in turn has been combined with the numerical predictions of drag coefficient (up to Reynolds number of 100) of a sphere to develop a generalized drag correlation for power‐law liquids encompassing both n > 1 and n < 1 which appears to apply up to much higher values of the Reynolds number. The available experimental data have been used to demonstrate the reliability and accuracy of the new correlation for shearthinning liquids. Also, in the limit of n = 1, this expression reproduces the standard drag curve with a very high accuracy.
Wood Pulp as Model Fluid to Mimic the Oxygen Mass Transfer in Aspergillus Niger Fermentation
Authors: Patel Nilesh , Goudreault Julie , Bagchee Shohini , Thibault Jules
Published: July 2010

To characterize the oxygen mass transfer in a fermentation system and to study the efficiency of mixing devices, model fluids are often used so that experimental conditions can be better controlled. In this study, wood pulp suspensions were used in an attempt to mimic the rheological properties of fermentation broths of Aspergillus niger. Two different types of bioreactor were used: a reciprocating plate bioreactor and a stirred (Rushton) bioreactor. The oxygen mass transfer coefficient (KLa) was measured for various mixing intensities, airflow rates and wood pulp concentrations, and a correlation of KLa as a function of the power input per unit volume and the superficial gas velocity was derived for each bioreactor and each pulp concentration. KLa was found to increase with agitation and air flow rate, and was adversely affected by an increase in pulp concentration in the case of the reciprocating plate bioreactor.
A Novel Photometric Technique to Detect the Onset of Asphaltene Precipitation at Low Concentrations: The Effect of Maltenes and Water
Authors: Horvath‐Szabo Geza , Masliyah Jacob H. , Czarnecki Jan
Published: July 2010

A photometer was utilized to measure the intensity of scattered light in toluene / heptane / asphaltenes mixtures. On the scattering‐intensity versus heptane‐to‐toluene ratio functions, two linear regions can be observed. The intersection of these regions determines the heptane‐to‐toluene ratio at which the precipitation of asphaltenes starts. The onset of asphaltene precipitation was determined as a function of asphaltene concentration in the presence and in the absence of maltenes as well as water. The onset is dependent on the asphaltene concentration. The presence of water promoted while the presence of maltenes inhibited the precipitation of asphaltenes.
Generalized Mathematical Modeling of Fluid‐Solid Non‐Catalytic Reactions Using Finite Volume Method: Multiple Reactions
Authors: Gupta Parthapratim , Saha Ranjit Kumar
Published: July 2010

Multiple Fluid Solid Non‐Catalytic (FSNC) reactions have been analyzed in a single particle based on sharp interface model (SIM) using Finite Volume Method (FVM), which is shown to be a suitable technique for solving moving boundary problems involving multiple chemical reactions and diffusion. The effect of various model parameters, like the order of reaction, Thiele modulus, thermicity and Arrhenius parameters, c20/c10, are found to have significant effects on independent, parallel and consecutive reactions.
Periodic Operation of Three — Phase Catalytic Reactors
Authors: Silveston Peter L. , Hanika Jiri
Published: July 2010

Periodic operation of three phase reactors has been explored for more than two decades. This type of forcing changes selectivity and can increase either conversion or throughput. Experiments and simulation demonstrate periodic flow interruption or variation enhances reaction rates for concurrent trickle beds provided reactants are in the gas phase or can be volatilized under bed operating conditions. Temperature excursions in trickle beds can be controlled by either flow variation or switching the feed between an inert and a reactant. Several approaches to increasing rate through faster mass transfer using flow pulsing have been studied. Pulsing flow can be induced by low amplitude modulation. Periodic switching of flow direction in airlift reactors increases gas hold up and thereby the mass transfer rate. Periodic operation of three phase reactors, thus, appears to be a fertile area for engineering research.
Applications of Markov Chains in Particulate Process Engineering: A Review
Authors: Berthiaux Henri , Mizonov Vadim
Published: July 2010

Processes involving particles, are known to exhibit extremely unpredictable behaviour, mainly due to the mesoscopic nature of granular media. Understanding particulate processes, not only for intellectual satisfaction, but also for process design and operation, basically requires a systems approach in modelling. Because they combine simplicity and flexibility, the stochastic models based on the Markov chain theory are very valuable mathematical tools to this respect. However, they are still largely ignored by the whole core of chemical engineering researchers. This motivates the existence of this review paper, in which we examine the three traditional issues: mixing and transport, separation and transformation.
Theoretical Analysis of the Onset of Gas Entrainment from a Stratified Region through a Single Side‐Oriented Branch at Moderate Froude Numbers
Authors: Ahmed Mahmoud , Hassan Ibrahim , Esmail Nabil
Published: July 2010

A theoretical investigation has been conducted for the prediction of the critical height at the onset of gas entrainment during single discharge from a stratified, two‐phase region, through a branch installed on an inclined flat wall. The predicted critical height at the onset of gas entrainment was proven to be a function of Froude number (Fr) and density ratio of the interface fluids. Three different experimental data sets at wall inclination angles of zero, 45 and 90 degrees (i.e. side, inclined and bottom branches) were used for comparisons. A good concurrence was illustrated between the experimental and theoretical values.