bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Studies on Hydration of Partially Sulphated CFBC Ash
Authors: Wu Yinghai , Anthony Edward J. , Jia Lufei
Published: July 2010

The hydration of partially‐sulphated fluidized bed combustor (FBC) ash with water was carried out at laboratory scale. The bottom ash fractions and the as‐received fly ash were hydrated for different lengths of time, at different temperatures between 5°C and 80°C. The free lime and calcium hydroxide content in the samples were analyzed before and after the hydration process. Scanning electron microscopy (SEM) with an energy dispersive X‐ray system (EDX) was employed to investigate the physical characteristics of the samples. X‐ray diffractograms (XRD) were used to obtain information on the phase composition. The current results show that, during the hydration treatment, the unreacted CaO in the partially‐sulphated material can be almost quantitatively converted to Ca(OH)2 but that the free lime content is not constant. It is also clear that effectiveness of the hydration depends on hydration time and temperature. In addition, the behaviour of different particle size fractions is different and there is evidence that the hydration of CaO is not the only reaction occurring in this system.
Régimes d'écoulement et mesure de l'épaisseur d'un film liquide ruisselant autour d'un tube horizontal
Authors: Louahlia‐Gualous Hasna , Baonga Jean Bosco , Panday Prabodh Kumar
Published: July 2010

Cet article présente les résultats d'une étude expérimentale sur la structure de l'écoulement et sur la mesure de l'épaisseur d'un film liquide ruisselant autour d'un tube horizontal. Il décrit la technique utilisée pour mesurer l'épaisseur du film en se basant sur la méthode de fluorescence induite par laser. Les essais ont été effectués avec le mélange eau/fluorescéine à une température constante et à la pression atmosphérique. En faisant varier le débit d'écoulement, plusieurs régimes d'écoulement sont identifiés. Nous avons mesuré la longueur d'onde en fonction du nombre de Reynolds du film. Les transitions entre les différents régimes d'écoulement sont étudiées en mettant en évidence le phénoméne d'hystérésis. Les valeurs des longueurs d'onde adimensionnelles sont comparées aux résultats de Hu et Jacobi (1998). Les résultats obtenus montrent l'évolution locale de l'épaisseur du film autour du cylindre. Ils sont comparés aux résultats de Rogers et Goindi (1989), Rogers (1986) et de Chyu et Bergles (1987). Une expression de l'évolution locale de l'épaisseur du film liquide est proposée en se basant sur les résultats des mesures.
Evolution of the Population of Bubbles in 2D Fluidized Beds
Authors: Prieto Juan J. , García Mónica , Ramos Guadalupe , Guardiola Jesús
Published: July 2010

The size of the bubbles in a solid‐gas 2D fluidized bed was estimated by image capture and digitalization using a CCD camera. It was confirmed that the size distribution for the bubbles in a slice of the bed was skewed, varying with the location of the slice. The results were analyzed using the Agarwal (1985) model, which is based on a population balance. For this model, four adjustable parameters are required, as well as the knowledge of bubble size just above the distributor. Experimental data were compared with values predicted by the model. The parameters that the model needs were obtained by three procedures: i) the constants supplied by Agarwal (1985) and Rowe and Everett (1972); ii) the parameters obtained from experimental data for a 1 cm wide slice bed; and iii) the parameters obtained by fitting the bubble diameter to all the bubbles in the bed. The second and third methods provided the best results.
Determination of Minimum Spouting Velocities in Conical Spouted Beds
Authors: Wang Zhiguo , Bi Hsiaotao T. , Lim C Jim , Su Pengcheng
Published: July 2010

Minimum spouting velocities in conical spouted beds have been obtained from pressure drops versus the superficial gas velocity curves, based on both increasing and decreasing the superficial gas velocity. It has been shown that the minimum spouting velocity from decreasing the superficial gas velocity is lower than from increasing the superficial gas velocity in most cases. This phenomenon is similar to that in conventional spouted beds and different from the early works. The experimental results also showed that there isn't significant difference in the pressure drop and Ums under identical operating conditions between semi‐circular and circular conical spouted beds, and the same Ums can be obtained from absolute pressure drops at any position above the gas inlet. The Ums is found to increase with increasing the cone angle and static bed height, as well as the gas inlet diameter to a less extent.
Characterization of Gas Spouted Beds Using the Rescaled Range Analysis
Authors: Xu Jian , Bao Xiaojun , Wei Weisheng , Shen Shikong , Bi H. T. , Grace J. R. , Lim C. J.
Published: July 2010

Differential pressure fluctuation measurements were conducted in a gas spouted bed of 120 mm in diameter at different axial and radial positions. Hurst's rescaled range analysis of the differential pressure fluctuation signals was successfully employed to recognize different flow regimes, i.e. packed bed, stable spouting and unstable spouting, and characterize their transitions. Obvious two‐phase behaviour, as suggested by two Hurst exponents, was observed in the stable spouting regime. It had also been found that the spouting behaviour in deeper spouted beds was significantly different from that in shallow spouted beds. The influences of measurement location and bed height on the Hurst exponents were discussed.
Voidage Profiles in a Slot‐Rectangular Spouted Bed
Authors: Freitas Luiz A. P. , Mitsutani Kenji , Lim C Jim , Grace John R. , Wei Weisheng
Published: July 2010

Local voidages were determined using optical fibre probes for 1.4 and 2.4 mm glass beads in slot‐rectangular spouted beds of width 150 mm. The effects of air inlet flow rate, slot width and bed thickness were investigated. Spout widths were determined from standard deviations of local voidage fluctuations. Both spout and annulus voidages increased with increasing air flow. Annulus voidages were usually higher than corresponding loose‐packed voidages and decreased with increasing height. Annulus and spout voidages were very sensitive to the air entry slot width and particle diameter. With increasing height, spouts became increasingly circular (three‐dimensional), despite the initial rectangular geometry.
Behaviour of Cohesive Powders in a Powder‐Particle Spouted Bed
Authors: Ishikura Toshifumi , Nagashima Hiroshi , Ide Mitsuharu
Published: July 2010

Behaviour of cohesive powders in a powder‐particle spouted Bed (PPSB) has been investigated under several operating variables and solids properties. The elutriation rate constant based on the hold‐up of fine powders in the bed decreased with a decrease in the size of fine powders, and with an increase in the size of coarse particles under a constant superficial gas velocity. This finding is quite different from the elutriation phenomena of particles more than 100 µm in size. Moreover, the mean residence time of fine powders increased with a decrease in the superficial gas velocity and the size of fine powders, and decreased with a decrease in the size of coarse particles.
Microcapsule Processing in a Spouted Bed
Authors: Baracat Marcela M. , Nakagawa Adriana M. , Freitas Luis A. P. , De Freitas Osvaldo
Published: July 2010

The aim of this study was to verify the feasibility of drying pharmaceutical microcapsules in a spouted bed with the aid of inert particles. The morphological character and total recovery of the drug model, indomethacin, were compared for spray and spouted bed dried microcapsules. Clusters formed by microcapsules coalescence in the spouted bed showed to have their size dependent on bed height. The total recoveries for three different bed heights were 53.18%, 60.76%, 70.70%, as compared to 95.65% for the spray drying process. The results showed that spouted beds are promising for the preparation of slow‐release drug systems.
Antimony Solubility and Speciation in Aqueous Sulphuric Acid Solutions at 298 K
Authors: Casas Jesús M. , Crisóstomo Gloria , Cifuentes Luis
Published: July 2010

This work is an experimental and theoretical study of antimony speciation and the solubility of Sb2O5, Sb2O3 and Sb2(SO4)3 at 298 K in aqueous sulphuric acid solutions (0 to 6 kmol/m3). A thermodynamic model was developed to quantify the solubility products and aqueous metal speciation. Main dissolved species were H3SbO3(aq) and H3SbO4(aq). The solubility of antimony increases with increasing solution acidity and with the presence of hydrogen peroxide in the solution. The following standard equilibrium constants at 298 K were obtained: Log K0(Sb2O5) = 11.7±0.5, Log K0(Sb2O3) = 32±1, and Log K0(Sb2(SO4)3) = 55±2.
Suggestion of a New Correlation for the Height of Shallow Dispersion Bed Formed in a Rotating Disc Contactor
Authors: Khadiv‐Parsi Parissa , Moosavian Mohammad‐Ali
Published: July 2010

A rotating disc contactor (RDC) was designed and constructed. The obtained experimental results for the heights of shallow dispersion beds formed in the separation zone of the extraction column, suggested a new correlation. It was found that any increase in dispersed phase flow rate or rotor speed caused an increase in the dispersion height. Also, the results revealed the profound effect of the continuous phase viscosity on the height of the bed. Within the ranges of experimental results, the proposed correlation was in good agreement with the data of shallow beds compared to previous proposed relations.
LDA Measurements on a Turbulent Gas/Liquid/Fibre Suspension
Authors: Pettersson Johan , Rasmuson Anders
Published: July 2010

Detailed continuous phase flow measurements (mean and RMS velocities) by Laser Doppler Anemometry (LDA) of a turbulent gas/fibre/liquid suspension in a rotary shear tester have been performed with simultaneous torque measurements. The model system comprises a refractive‐index matched suspension in the 4‐12% wt. range with gas contents up to 15% vol. The two transition points, found by Andersson and Rasmuson (2000), were detected also with gas present and appear at higher impeller speeds with increasing gas and fibre concentrations. Plotting RMS and mean velocities versus impeller speed and power input, it is found that both decrease with increasing gas and fibre contents.
Some Characteristics of Stirred Vessel Flows of Dilute Polymer Solutions Powered by a Hyperboloid Impeller
Authors: Cavadas A. S. , Pinho F. T.
Published: July 2010

Measurements of the power consumption and mean and turbulent velocities in the wall jet of a stirred vessel flow, powered by a hyperboloid impeller, were carried out. The fluids were aqueous solutions of tylose, CMC and xanthan gum (XG), at weight concentrations ranging from 0.1% to 0.6%, which exhibited varying degrees of shear‐thinning and viscoelasticity. The hyperboloid impeller parameter k of Metzner and Otto (1957) was found to be equal to 27.2 ±4. In the Reynolds number range of 103 to 3 × 104 the mixing power was reduced for all non‐Newtonian fluids, but never by more than 13%. The flows of the 0.2% CMC and 0.2% XG solutions were found to be less turbulent than those of water, especially for the latter fluid where a reduction in axial rms in excess of 50% was found in the wall jet. This was attributed to elasticity effects and especially to the high zero shear viscosity of the latter fluid.
Heat Transfer to an Isolated Bubble Rising in a High‐Temperature Incipiently Fluidized Bed
Authors: Wu Wenyuan , Agarwal Pradeep K.
Published: July 2010

Very few experimental data are available on the heat transfer between bubble and emulsion phases; no data are available at high temperatures. The effects of bed particle type and size, bubble size, and bed temperature on the heat transfer coefficient were examined in this experimental and modelling study. The heat transfer coefficient was found to increase to a maximum, and then decrease as the bubble mass increased in the bubble mass range investigated. Increase in bed temperature led to a significant decrease in the heat transfer coefficient. The simple mathematical model developed earlier was extended to include operation at high temperature.
Stability of Homogeneous Fluidization Under Extreme Conditions of Operation
Authors: Foscolo Piero , Gibilaro Larry
Published: July 2010

Recently reported results for the behaviour of fluidized beds under extreme conditions of operation are shown to be in good quantitative agreement with the predictions of a long established fluid‐dynamic criterion for the onset of instability of the homogeneously fluidized state. The four sets of experiments relate to fluidization under very high pressure conditions (by supercritical fluids), at very high and very low effective gravitational field strengths, and at very low particle concentrations.
Drying of Suspensions in the Draft Tube Spouted Bed
Authors: Arsenijević Zorana L. J. , Grbavcić Zeljko B. , Garić‐Grulović Radmila V.
Published: July 2010

A draft tube spouted bed dryer with inert particles was used for drying suspensions. The effects of the operating conditions on dryer throughput and product quality were investigated. Experiments were performed in a cylindrical column 215 mm in diameter with a draft tube 70 mm in diameter and 900 mm in length. The bed was made of polyethylene particles, 3.3 mm in diameter with a density of 921 kg/m3. The fungicide Zineb, calcium carbonate, calcium stearate and pure water were used as feeding materials. A drying model using the continuity and momentum equations for turbulent accelerating two‐phase flows and conventional rate equations is proposed and discussed. The work is relevant for estimating dryer performance.
Development of Two‐point Dynamic Method for Evaluating Extraction Columns
Authors: Li Hongbo , Tang Xiaojin , Luo Guangsheng , Wang Jiading
Published: July 2010

The steady‐state method by measuring the concentration profile along the column height is an effective way, but it is a time and material consumption method for large extraction columns. In order to investigate the axial‐mixing and mass transfer performances in a large pulsed‐sieve‐plate extraction column with the diameter of 150mm, a two‐point dynamic method with mass transfer based on the diffusion model has been developed. The results proved that the two‐point dynamic method has the advantages of good accuracy, simple boundary equations and flexible sampling position over the traditional single‐point dynamic method. It is a reliable tool for studying the axial‐mixing and the mass transfer performances.
New Approach to Solve a Model for the Effective Solid Stress Distribution in Conical Spouted Beds
Authors: Costa Esly F. , Passos M. Laura , Biscaia Evaristo C. , Massarani Giulio
Published: July 2010

Charbel et al. (1999) have investigated the flow stability in conical spouted beds by modeling the effective solid stress distribution in the annular region as a function of the failure state under which the spout‐annulus interface is formed. However, due to the complexity in solving the momentum balance equations for the solid phase, the model application has been restricted to one case. This work is aimed at developing a new methodology to solve this set of algebraic differential equations, using optimization techniques to determine the model parameter. This methodology has improved the model solution extending its application for any other case.
Multiobjective Optimization of Simulated Moving Bed Reactor and its Modification — Varicol Process
Authors: Subramani Hariprasad J. , Zhang Ziyang , Hidajat Kus , Ray Ajay K.
Published: July 2010

A comprehensive optimization study on a Simulated Moving Bed Reactor (SMBR) system is reported in this article for the direct synthesis of Methyl Tertiary Butyl Ether (MTBE). In addition, the SMB technology, which is based on synchronous switching of ports, was modified to a new more flexible Varicol process based on non‐synchronous switching. Multi‐objective optimization has been performed for both SMBR and Varicol and their efficiencies were compared. A state‐of‐the‐art optimization technique, viz., Non‐dominated Sorting Genetic Algorithm (NSGA) that allows handling of these complex optimization problems is employed in this study.
Neural and Hybrid Neural Modeling and Control of Fed‐Batch Fermentation for Streptokinase: Comparative Evaluation under Nonideal Conditions
Authors: Patnaik Pratap R.
Published: July 2010

Fermentations involving competition between two or more kinds of cells under nonideal conditions show complex profiles that are sensitive to the extra‐cellular environment. These fermentations therefore require accurate and rapid on‐line data acquisition and control. However, both on‐line measurements and modelling are difficult and expensive for large bioreactors, thus limiting the usefulness of model‐based control. While neural networks offer an alternative, they require extensive training and can be difficult to optimize for large arrays. Hybrid networks combining a few neural networks with some mathematical equations offer a good compromise. The possibility of using a hybrid model for simulation‐cum‐control has been examined here for the fed‐batch production of streptokinase. Under noideal conditions, hybrid neural models outperformed both mathematical models and arrays of neural networks, thus suggesting their viability for large‐scale fermentation monitoring and control.
Relationship between Riser and Downcomer Gas Holdups in Semi‐batch Circulating Bubble Columns
Authors: Al‐Masry Waheed A. , Al‐Dughaither Abdullah A. , Al‐Samari Turki A.
Published: July 2010

Gas holdups were measured in a circulating bubble column (CBC) using air‐water system with various additives. The liquid volume in the gas separator affected downcomer gas holdup up to volume ratio equal to 6%. Presence of surface active agents, alcohols, solid particles had little effects on the gas holdups ϵgd — aϵgr relationships. The gas holdups relationships are theoretically related by a single parameter model ϵgd = aϵgr — a + 1, and empirically by two parameter model ϵgd = aϵgr — constant. The theoretical model yielded a values ≅ 0.45, while the empirical model yielded a values ≅ 1.16. Analogy between the two models (Contreras et al., 1998) will lead to incorrect conclusions.
Processibility of Athabasca Oil Sand Using a Laboratory Hyd ro t ransport Extraction System (LHES)
Authors: Wallwork Vince , Xu Zhenghe , Masliyah Jacob
Published: July 2010

A novel laboratory scale apparatus has been developed and used to assess the extraction performance of oil sands under conditions analogous to current industrial processes. The apparatus can be used to investigate independently, the liberation of bitumen from the sand as well as air‐bitumen attachment and bitumen recovery. Experiments show that lower operating temperatures have a detrimental effect on bitumen recovery and controlled air addition is beneficial for recovery. The liberation of bitumen from sand grains has been found to proceed faster than air attachment and bitumen recovery, making the flotation the ratelimiting step in the extraction process. The potential benefit of staged air injection into hydrotransport pipelines as a possible process aid is discussed.
A New Device to Determine Bitumen Extraction from Oil Sands
Authors: Luthra Manoj , Lopetinsky Robert J. G. , Sanders R Sean , Nandakumar K , Masliyah Jacob H.
Published: July 2010

The Batch Extraction Unit (BEU) has been in use since the 1970's for studying the extraction of bitumen from oil sand. The present study investigates an alternative method for estimating bitumen recovery, based on visualization of oil sand slurry undergoing digestion. A Couette flow device is loaded with known amounts of oil sand and water. Air is bubbled through the oil sand slurry, while it is subjected to controlled chemical conditions and shear environment. Images of the slurry are captured at various time intervals and then analyzed using image analysis software, which selects black areas based on the gray scale intensities of the area in view. The variation of the black area with time is used as a measure of bitumen recovery. The technique provides quick estimates of final recovery, while enabling kinetic studies of the liberation and recovery processes. The experimental set‐up offers great flexibility in selecting conditions for the digestion of oil sands.
A Two Level Fractional Factorial Design to Test the Effect of Oil Sands Composition and Process Water Chemistry on Bitumen Recovery from Model Systems
Authors: Fong Nelson , Ng Samson , Chung Keng H. , Tu Yun , Li Zaifeng , Sparks Bryan D. , Kotlyar Luba S.
Published: July 2010

To overcome the compositional variability inherent to natural oil sands we use extraction tests with model oil sands (MOS) systems in a systematic, experimental design study. Eight significant variables from screening tests in earlier work are tested here. Namely, concentrations of bitumen, silica fines, sodium kaolinite, illite and montmorillonite. In addition, we tested different concentrations of Ca2+, Mg2+, and Na+ in the synthetic process water used with bitumen separation tests. A two level, fractional factorial experimental design allowed testing of the selected variables using only 16 runs. In addition, sodium hydroxide was added as a ninth variable and four repeat tests allowed evaluation of precision. The resulting bitumen recovery model explained 94% of the data variation. The associated parameter estimates were in general agreement with previous experimental observations and with actual operational experience.
Effect of Temperature on the Stability of Froth Formed in the Recycle Process Water of Oil Sands Extraction
Authors: Choung Jaewon , Walker Justin , Xu Zhenghe , Masliyah Jacob
Published: July 2010

The formation of a stable froth on the top of separation vessels plays an important role in bitumen flotation during bitumen recovery from oil sands. The effect of temperature on the stability of froth using recycle process water employed in bitumen extraction was investigated using a water column. The froth became less stable with increasing solution temperature. Once the solution temperature increased above 50°C, irreversible precipitation of the surfactants present in the recycle process water was observed, resulting in a less stable froth.
Determining Bitumen Viscosity Through Drop Shape Recovery
Authors: Moran Kevin , Yeung Anthony
Published: July 2010

In determining the viscosity of bitumen using conventional methods, the measurements must be conducted at extremely slow shear rates to avoid dissipative heating. In this study, bitumen viscosity is measured at room temperature using a drop shape recovery technique which, as will be shown, is immune to any problem of dissipative heating. The method involves stretching a small droplet of bitumen (and in general, of any viscous liquid) with micropipettes and allowing it to recover to its original spherical shape; the dimensions of the droplet can be as small as several micrometres. The shape recovery process is driven by capillary forces and rate‐limited by the droplet viscosity. As such, knowing the interfacial tension, the droplet viscosity can be determined accurately from the relaxation dynamics. With conventional viscometers, the problem of dissipative heating often increases linearly with the viscosity and quadratically with the shear rate. This is in contrast with shape recovery experiments, where dissipative heating is independent of shear rate and varies inversely with the viscosity.
Hydrogen and Oxygen Bubble Attachment to a Bitumen Drop
Authors: Gu Guoxing , Sanders R. Sean , Nandakumar K. , Xu Zhenghe , Masliyah Jacob H.
Published: July 2010

Air bubble – bitumen attachment is a critical step in the flotation of bitumen from mined oil sand. In this study, single bubble – bitumen drop attachment was observed directly using a novel experimental technique. Induction time is determined and used as an indication of bubble‐bitumen attachment potency for both hydrogen and oxygen bubbles. The attachment tests were conducted in deaerated municipal water (City of Edmonton tap water) at temperatures ranging from 22–50°C. Induction times measured for hydrogen bubble attachment were shorter than those for oxygen bubbles. Coalescence tests were also conducted in the absence of bitumen, and showed that hydrogen bubbles coalesced more rapidly than oxygen bubbles in both deaerated municipal water and clear (solids‐free) process water.
Determination of Decompression Wave Speed in Rich Gas Mixtures
Authors: Botros Kamal K. , Studzinski Wojciech , Geerligs John , Glover Alan
Published: July 2010

Experimental data on the decompression wave speed of a conventional gas mixture and three other rich gas mixtures with varying C1 from 70 to 82% have been collected. An NPS 2 stainless steel expansion tube test rig has been constructed at TCPL Gas Dynamic Test Facility (GDTF) in Didsbury, AB, Canada, specifically for this task. Decompression wave was generated by a rupture disc at the end of the tube, which was instrumented with eight high frequency response pressure transducers located along the tube. The facility has the following three distinct capabilities: high initial pressures of up to 22 MPa, low initial temperature down to ‐20°C, and flexibility in testing any rich gas mixtures. The decompression wave speed data are presented in terms of the decompression expansion pressure ratio for all four gas mixtures and three initial line pressure of ∼ 10, 14 and 20 MPa. Comparison between experimentally obtained decompression wave speeds and those predicted by GASDECOM is also made for each test.
Mixing Time Studies in Multiple Impeller Agitated Reactors
Authors: Kasat Gopal R. , Pandit Aniruddha B.
Published: July 2010

Mixing time studies have been carried in a 0.3m diameter and 0.9m tall vessel equipped with three impellers. Conductivity measurement technique has been used for the measurements of mixing time. Effect of the various parameters i.e. tracer density, tracer volume, speed of rotation and impeller combination on mixing time has been studied for two impeller combinations used viz. PTD‐PTD‐PTD and PTD‐PTD‐DT. A compartment model (with one fitted parameter, the exchange flow rate QE) with single compartment per agitation stage has been used to predict the conductivity response and the exchange coefficients are calculated from the model parameter. An attempt has been made to explain the experimental results on the basis of the liquid phase axial dispersion coefficient and cell residence time, calculated from the model parameter QE
Effects of Gas‐Agitation and Packing on Hydrodynamics and Mass Transfer of Extraction Column
Authors: Xiong Jieming , Zhang Liping
Published: July 2010

The effects of gas‐agitation and packing on hydrodynamics and mass transfer were investigated through experiments with air‐kerosene (benzoic acid)‐water system and corrugated‐packing of calendering plate with hole. The holdup of gas, holdup of dispersed liquid phase and mass transfer coefficient increase and the flooding velocity decrease with the increase in superficial gas velocity. Over‐agitation of gas causes over‐dispersion and emulsification of dispersed liquid phase, reduction of mass transfer performance and even flooding. The mass transfer performance of a packed column is far better than that of an unpacked column.
Penetration of Shear Flow Into an Array of Rods Aligned With the Flow
Authors: Davis Anthony M. J. , James David F.
Published: July 2010

Shear flow over a square array of widely‐spaced rods aligned with the flow is investigated using singularity methods to solve Stokes equation. The flow field is determined for various arrays occupying a fraction of a Couette channel, for solid volume fractions from 0.001 to 0.1. Flow penetration into an array is quantified by the slip velocity at the array edge. This velocity is much greater than when the flow is across the array but still less than the value predicted by the use of Brinkman's equation.
A New Application of the Severity Factor Kinetic Model: Thermal Plasma Treatment of Black Liquor
Authors: Yargeau Viviane , Marcos Bernard , Soucy Gervais
Published: July 2010

The kinetic analysis of the treatment of black liquor by a thermal process can be performed in the conventional overall kinetic approach. However, while the detailed reaction mechanism remains unknown, the experimental analysis of black liquor treatment by submerged plasma demonstrates that the operating conditions (catalyst, plasma gas, temperature…) modify the kinetics and render this approach inefficient. The phenomenological approach based on the severity factor developed for the kinetic analysis of lignocellulose decomposition, is then proposed as an alternative to the conventional approach. The 3‐parameters model is validated for decomposition of formic acid and for sulfur oxidation.
Extraction of Gold (III) Ions from Aqueous Solutions Using Polyamine Type Surfactant Liquid Membrane
Authors: Kargari Ali , Kaghazchi Tahereh , Soleimani Mansoureh
Published: July 2010

Experimental results of extraction of gold (III) ions from aqueous solutions by a polyamine type liquid membrane are presented. The effects of various parameters such as concentration of gold ions in the external phase, concentration of carrier, concentration of the internal phase reagents, pH of the external phase and the speed of agitation on the extraction rate were studied. The results show that by proper selection of the extraction conditions, nearly all of the Au (III) ions present in a highly concentrated feed solution was extracted within a few minutes.
Adiabatic Calorimetric Decomposition Studies of 35 Mass% Hydroxylamine Hydrochloride/water
Authors: Cisneros Lizbeth O. , Rogers William J. , Mannan M Sam
Published: July 2010

The HH (35 mass% hydroxylamine hydrochloride/water solution) and HH‐ind (stabilized 35 mass% hydroxylamine hydrochloride/water solution for industrial use) decomposition reaction has an onset temperature of ∼145°C. The measured gas phase decomposition products are 0.25 mol N2 and 0.06 mol O2 per mol of hydroxylamine hydrochloride with small quantities of N2O and H2, and a trace amount of NO for a total noncondensable gas production of ∼0.39 mol/mol of hydroxylamine hydrochloride. The reaction system is tempered by the evaporation of the solvent (water) and the reaction is drastically catalyzed by stainless and carbon steel.
Review on Mixing Characteristics in Solid‐Liquid and Solid‐Liquid‐Gas Reactor Vessels
Authors: Kasat Gopal R. , Pandit Aniruddha B.
Published: July 2010

Mechanically agitated reactors with single and multiple impeller systems are used in the industry for the various three‐phase mixing processes such as crystallization, fermentation, and hydrogenation, etc. The paper reviews the experimental work reported in the literature along with different techniques used for the measurement of the specific quantities such as minimum or critical impeller speed for solid suspension. The work critically surveys the literature and makes specific recommendations for the use of appropriate correlations and conditions to be used for the success of such equipment. This assessment will put all the relevant literature on a common footing and will help to validate work reported earlier.
Dibenzothiophene HDS Over Sulphided CoMo on High‐Silica USY Zeolites
Authors: Lara Gerardo , Escobar José , De Los Reyes José A , Barrera María C. , Colín José A. , Murrieta Florentino R.
Published: July 2010

USY faujasites (SiO2/Al2O3 = 12, 30 and 80) were used as hydrodesulphurization (HDS) catalyst supports. Mo, Co and P were impregnated at two concentrations: ∼12.5, ∼3 and ∼1.6 mass %; ∼18, ∼5.5 and ∼2.2 mass % (CL and HL series, respectively). Surface acidity decreased after Co‐Mo‐P deposition. Sulphided catalysts were tested in dibenzothiophene (DBT) HDS (320°C, 5.59 MPa). The HDS rate slightly increased with both SiO2 content and Co‐Mo‐P loading. High selectivity to hydrogenated products suggested deficient Mo promotion in CL solids. Improved Mo promotion by Co (HL series) could be responsible for higher activity and marked selectivity to desulphurization to biphenyl.
Viscoelastic (Non‐Fickian) Diffusion
Authors: De Kee D. , Liu Q. , Hinestroza J.
Published: July 2010

This review paper deals with mass transport in macromolecular materials. The study of mass transport through polymeric composite materials for example has applications in a variety of areas such as coatings, packaging and gas separations, to name just a few. Here we discuss several models for diffusion as well as several experimental techniques. In particular, we discuss models for case II diffusion, from a continuum mechanics point of view as well as via a mesoscopic theory. Variables such as temperature, molecular structure and mechanical deformation, affecting mass transport are also discussed.
Geometrical Models for Tortuosity of Streamlines in Three‐Dimensional Porous Media
Authors: Yun Meijuan , Yu Boming , Xu Peng , Wu Jinsui
Published: July 2010

Based on the assumption that some particles in porous media are unrestrictedly overlapped and hence of different configurations, this paper presents three three‐dimensional geometry models for tortuosity of streamlines in porous media with spherical, cubic and plate‐like particles, respectively. The proposed models are expressed as a function of porosity with no empirical constant, and they are helpful for understanding the physical mechanism for tortuosity of flow paths in three‐dimensional porous media. The model predictions are compared with those from the available correlations obtained by experimental data, and good agreement is found between them.
Cometabolic Transformation of 2‐Chlorophenol and 4‐Chlorophenol in the Presence of Phenol by Pseudomonas putida
Authors: Loh Kai‐Chee , Wu Tingting
Published: July 2010

Biotransformation of 2‐chlorophenol (2‐cp) and 4‐chlorophenol (4‐cp) in the presence of phenol by Pseudomonas putida (ATCC 49451) was investigated. Strain ATCC 49451 was unable to utilize 2‐cp and 4‐cp as the sole carbon and energy source. In the presence of phenol as a growth substrate, 2‐cp and 4‐cp could be transformed through cometabolism. It was found, however, that cell growth and phenol degradation were strongly inhibited by the presence of 2‐cp and 4‐cp. A much longer lag phase (19 h versus 3 h) occurred with the mere addition of 40 mg/L 2‐cp and 100 mg/L 4‐cp. Further increase in 2‐cp and 4‐cp concentrations resulted in incomplete transformation: only 80% of the initial 100 mg/L 4cp and 50% of the initial 40 mg/L 2‐cp could be degraded in the presence of 200 mg/L phenol. Interactions between substrates affected cell growth and substrates degradation significantly and both 2‐cp and 4‐cp were toxic to the cells. Kinetic models for cell growth as well as substrate transformation were established to simulate the experimental data. The form of the kinetic models and magnitude of the model parameters (K2 = 5.62 mg/L > K3 = 3.57 mg/L; kd2 = 17.8 mg/L < kd3 = 51.5 mg/L) indicate that 2‐cp and 4‐cp exhibited different inhibition and toxicity effects on the cells and their degradation capacities. Kinetics also revealed that the toxicity effect of the chlorophenols dominated over the competitive inhibition effect.
A Short Note on Steady State Behaviour of a Petlyuk Distillation Column by Using a Non‐Equilibrium Stage Model
Authors: Abad‐Zarate Erika Fabiola , Segovia‐Hernández Juan Gabriel , Hernández Salvador , Uribe‐Ramírez Agustín R.
Published: July 2010

A Petlyuk distillation column, considering equilibrium and non‐equilibrium stage models, was studied. Rigorous simulations were conducted using Aspen Plus™ RATEFRAC Module for the separation of ternary mixtures. According to the equilibrium model, the energy‐efficient design of the Petlyuk column requires that the intermediate component be extracted from the maximum point in the composition profile in the main column. It was found that, for the intermediate component, mass transfer occurs from the vapour to the liquid phase from the top of the column to the stage where the side stream is extracted, from this point mass transfer occurs in the opposite direction. This point, considering the non‐equilibrium model, corresponds to the stage in which the net mass transfer rate is zero. For the case of two segments per stage, it was found that the heat duties predicted by the equilibrium model are significantly lower than those obtained by using the non‐equilibrium model, which is consistent with previous reported results. However, it is important to say that despite the higher energy duty predicted by the non‐equilibrium model; both models predict significant energy savings.
Comparison of Antioxidant Activity of Ethanolic Extracts of Propolis Obtained by Different Extraction Methods
Authors: Jun Xi
Published: July 2010

The antioxidant activities of the ethanolic extracts of propolis obtained by different extraction methods (high hydrostatic pressure extraction, leaching at room temperature and heat reflux extraction) were investigated in relationship to their total polyphenol and flavonoid contents by two different assays, namely, the β‐carotene bleaching and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical scavenging assay systems. The results showed that the ethanolic extracts of propolis obtained by high hydrostatic pressure extraction and leaching at room temperature had relatively strong antioxidant activities, which may be correlated with the total polyphenol and flavonoid contents. Antioxidant activities of ethanolic extracts of propolis obtained by high hydrostatic pressure extraction were the same as those of ethanolic extracts of propolis obtained by leaching at room temperature. Leaching at room temperature usually needs a few days, and can take even more than 7 d, while high hydrostatic pressure extraction needs only 1 min. These findings further illustrate that the high hydrostatic pressure extraction has a bright prospect for extracting flavonoids from propolis.
Mass Transport Through PDMS/Clay Nanocomposite Membranes
Authors: Liu Quan , de Kee Daniel
Published: July 2010

Poly(dimethylsiloxane)/clay nanocomposite membranes have been synthesized and mass transport properties through those nanocomposite membranes have been investigated. The effect of mechanical deformation on the transport properties of the PDMS (nanocomposite) membranes has also been studied. With the introduction of clay particles into the polymer matrix, mass transport is reduced, likely due to the longer diffusion path, which slows the diffusion process. The effect of membrane extension on diffusion is more complicated. Under small deformation, the permeation flux decreases, but under high deformation, it shows an enhanced diffusion. As the clay particle concentration increased, the effect of external deformation is reduced, and an enhanced diffusion is observed.
Association Equation of State for Hydrogen‐Bonded Substances
Authors: Vafaie‐Sefti Mohsen , Modarress Hamid , Meibodi Majid Emami , Mousavi‐Dehghani Seyyed Ali
Published: July 2010

An association equation of state (AEOS) has been proposed for hydrogen‐bonded compounds. To obtain this AEOS, the compressibility factor was assumed to consist of two parts: the physical part due to physical interactions of molecules; and the chemical part due to molecular association by hydrogen bonding of molecules. The physical part of the compressibility factor was represented by the MMM EOS for non‐polar compounds proposed by Mohsen‐Nia et al., Fluid Phase Equilib. 206, 27‐39 (2003), and the chemical part of the compressibility factor was deduced by proposing a molecular association model of infinite series.
A Simple Modification of the Pitzer Method to Predict Second Virial Coefficients
Authors: Vetere Alessandro
Published: July 2010

A simple modification of the Pitzer relation to calculate second virial coefficients of polar compounds is proposed. The proposed modification is based on the use of a new parameter, β, which embodies both the contributions of acentricity and polarity to second virial coefficient values. The analytical form of the Pitzer relation is preserved and its performances are improved. Rules are given to calculate β for several classes of compounds which require only the knowledge of a few well known properties of pure compounds. A comparison between the new method and the Pitzer‐Tsonopoulos relation is made on the basis of the experimental Bi data of nearly 50 compounds.
Frictional Pressure Drop of Air Non‐Newtonian Liquid Flow through Helical Coils in Horizontal Orientation
Authors: Biswas Asit Baran , Das Sudip Kumar
Published: July 2010

Investigations have been carried out to evaluate the two‐phase frictional pressure drop for air non‐Newtonian liquid flow through helical coils in horizontal orientation. The experiments performed using 36 different helical coils and 4 different concentrations of sodium salt of carboxymethyl—cellulose (SCMC) as non‐Newtonian liquids. The effects of air and liquid flow rate, coil diameter, helix angle and liquid properties‐ on two‐phase frictional pressure drop have been discussed. An attempt has been made to fit the experimental two‐phase frictional pressure drop data by the Lockhart and Martinelli, Chem. Eng. Prog. 45, 39–48 (1949) correlation and the modified Lockhart‐Martinelli correlation as presented by different authors. In another approach, friction factor method was adopted to correlate the experimental data by dimensional analysis. The correlation developed predicts the two‐phase frictional pressure drop with acceptable statistical accuracy.
Detection and Diagnosis of Plant‐Wide Oscillations
Authors: Shoukat Choudhury M. A. A. , Kariwala Vinay , Thornhill Nina F. , Douke Hisato , Shah Sirish L. , Takada Haruo , Forbes J. Fraser
Published: July 2010

This paper presents some emerging techniques for detection and root‐cause diagnosis of plant‐wide oscillations, and demonstrates their efficacy through a successful industrial case study. The recently proposed autocorrelation function based method (Thornhill et al., J. Proc. Control 13, 91–100, 2003a) is used for detection of oscillations in the process measurements. Signals having common oscillations are analyzed for the presence of valve stiction using higher order statistical methods (Choudhury et al., Automatica 40, 1719–1728, 2004b). A method employing changes in controller gain is proposed for distinguishing an internally generated oscillation from an external oscillatory disturbance. This method of changing controller gain is used to confirm the presence of control valve stiction. The proposed techniques have been used successfully to identify the root cause of plant‐wide oscillations in an industrial case study using routine operating data.
Miscibility Determination from Gas‐Oil Interfacial Tension and P‐R Equation of State
Authors: Ayirala Subhash C. , Rao Dandina N.
Published: July 2010

Recently a new experimental technique of vanishing interfacial tension (VIT) has been developed to enable rapid and cost‐effective determination of miscibility in gas‐oil systems. In this study, VIT experiments have been extended to two standard gas‐oil systems of n‐decane‐CO2 and live decane‐CO2 at elevated pressures and temperatures. The VIT miscibilities of the two standard gas‐oil systems and the two reservoir crude oil‐gas systems, namely Rainbow Keg River (RKR) and Terra Nova, were compared with Peng‐Robinson (P‐R) equation of state (EOS) calculations. The close match of VIT miscibilities with other conventional experimental techniques in the standard gas‐oil systems, as well as the reasonable match obtained with untuned PR‐EOS calculations for several systems studied, clearly demonstrates the sound conceptual basis of VIT technique to determine fluid‐fluid miscibility in multi‐component hydrocarbon systems.
Modelling Gas Holdup in Flotation Column Froths
Authors: Bhole Manish R. , Joshi Jyeshtharaj B.
Published: July 2010

A one‐dimensional steady‐state model is developed for the prediction of axial variation of the gas holdup in flotation column froths. Froth is considered as an inverse fluidized bed of bubbles and hence the frictional pressure gradient is obtained based on the energy balance. Pressure gradient can also be obtained from the Ergun equation with adjustable constants. The model correctly captures the effect of superficial gas velocity, superficial liquid velocity and bubble diameter on the variation of the gas holdup along the froth height. The predictions of the model are in agreement with the experimental data from the literature.
The Use of Simplified or Misspecified Models: Linear Case
Authors: Wu Shaohua , Harris T. J. , Mcauley K. B.
Published: July 2010

Simplified models have many appealing properties and sometimes give better parameter estimates and model predictions, in sense of mean‐squared‐error, than extended models, especially when the data are not informative. In this paper, we summarize extensive quantitative and qualitative results in the literature concerned with using simplified or misspecified models. Based on confidence intervals and hypothesis tests, we develop a practical strategy to help modellers decide whether a simplified model should be used, and point out the difficulty in making such a decision. We also evaluate several methods for statistical inference for simplified or misspecified models.
On‐Line Feedback Control for Optimal Periodic Control Problems
Authors: Höffner Kai , Hudon Nicolas , Guay Martin
Published: July 2010

In this paper a method for generating periodic orbits for a class of non‐linear systems is presented. A periodic Hamiltonian system is defined as the target equilibrium for non‐linear systems in strict feedback form. A parameter dependent non‐linear periodic system description is introduced for a two‐dimensional subsystem and extended to higher dimensions using backstepping. Extremum seeking is used as a parameter update law that guarantees the convergence of the system to the optimal periodic orbit with respect to a given parameterization. The procedure resulted in an on‐line feedback control implementation that typically steers the system to a suboptimal solution that nevertheless improves the static optimization solution. Typical examples from optimal periodic control literature are used to illustrate the application of this approach.
Simulation‐Based Design of Dual‐Mode Controller for Non‐Linear Processes
Authors: Lee Jong Min , Lee Jay H.
Published: July 2010

This paper presents a simulation‐based approach for designing a non‐linear override control scheme to improve the performance of a local linear controller. The higher‐level non‐linear controller monitors the dynamic state of the system and calculates an override control action whenever the system is predicted to move outside an acceptable operating regime under the local controller. The design of the non‐linear override controller is based on a cost‐to‐go function, which is constructed by using simulation or operation data. The cost‐to‐go function delineates the admissible region of state space within which the local controller is effective, thereby yielding a switching rule.
Approximate Pole Placement with Dominance for Continuous Delay Systems by PID Controllers
Authors: Wang Qing‐Guo , Liu Min , Hang Chang Chieh
Published: July 2010

It is well known that a continuous‐time feedback system with time delay has infinite spectrum and it is not possible to assign such infinite spectrum with a finite‐dimensional controller. In such a case, only the partial pole placement may be feasible and hopefully some of the assigned poles are dominant. But there is no easy way to guarantee dominance of the desired poles. In this paper, an analytical PID design method is proposed for continuous‐time delay systems to achieve approximate pole placement with dominance. Its idea is to bypass continuous infinite spectrum problem by converting a delay process to a rational discrete model and getting back continuous PID controller from its discrete form designed for the model with pole placement. Simulation results are included to illustrate the effectiveness of this method.