bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic analysis of changes in diffusion and sorption parameters in the reaction of SO2 with activated soda ash
Authors: Doǧu Gülsen , Keskin Alne , Doǧu Timur 
Published: March 2009

AbstractVariations in pore structure cause significant changes in diffusion resistance and adsorption characteristics during the reaction of SO2 with activated soda. Breakthrough and moment analysis of the SO2‐activated soda ash reaction showed that the effective diffusion coefficient of SO2 in the solid product (mostly Na2SO3) was about three times smaller than its value in the original activated soda. About 30% of the diffusion flux of SO2 in the solid product was found to be due to surface diffusion. The adsorption equilibrium constant of SO2 on the solid product was found to be about half the value of the adsorption equilibrium constant on activated soda. It was also determined that SO2 was irreversibly adsorbed on the solid product Na2SO3 at 200°C and 3.7 atm. The gaseous product CO2 was not adsorbed on the solid product while it was slightly adsorbed on activated soda.
On‐line estimation of microbial specific growth‐rates: An illustrative case study
Authors: Dochain D. , Pauss A. 
Published: March 2009

AbstractThis paper deals with the on‐line estimation of the specific growth rate in a fermentation process in the case when a soluble product is measured on‐line. The proposed algorithm belongs to a larger class of on‐line estimation algorithms which present the following advantages: they do not require any analytical expressions for the specific growth rate; their theoretical stability and convergence have been emphasized; since their structure includes a filtering effect, the estimation results exhibit less erratic values for the specific growth rate than when obtained by direct calculation from the biomass concentration equation. Real‐life results on an ethanol producing process are presented. Finally. it is shown how estimation results can be used for modelling purposes.
Effect of benzene and thiophene on rate of coke formation during naphtha pyrolysis
Authors: Sahu Durjyogharan , Kunzrw Deepak 
Published: March 2009

AbstractThe effect of benzene or thiophene addition to the feed on the rates of coke formation during naphtha pyrolysis has been investigated in a jet‐stirred reactor at atmospheric pressure in the temperature range of 1073‐1103 K. In addition, the effect of temperature, space time, weight ratio of steam to naphtha and the material of construction on the rate of coke deposition was also studied.The rate of coke formation increased as the temperature, space time and aromatic content of the feed was increased whereas it decreased with an increase in the weight ratio of steam to naphtha or the thiophene content of the feed. Addition of thiophene increased the rate of naphtha pyrolysis and significantly reduced the aromatic yields. Rates of coke formation for both thiophene‐free and thiophene‐containing naphtha could be modeled by power law expressions involving the aromatics.
Preparation and characterization of Pt/silicalite catalysts with high Pt loadings
Authors: Rangwala H.A. , Szymura J.A. , Wanke S.E. , Otto F.D. 
Published: March 2009

AbstractMethods for preparing Pt/silicalite catalysts are described. Equilibration of silicalite, a pentasil zeolite, in aqueous solutions of Pt(NH3), Cl2 containing excess ammonia resulted in Pt/silicalite catalysts with Pt loadings of ≥7 wt%. The Pt/silicalite catalysts were characterized by hydrogen chemisorption, X‐ray diffraction and transmission electron microscopy. The characterization studies showed that the majority of the Pt in the heavily loaded catalysts was located in the silicalite pores, and the Pt dispersions in these catalysts exceeded 0.8.
Coal surface conditioning for electrostatic separation
Authors: Zhou G. , Brown J. D. 
Published: March 2009

AbstractIn analogy with froth flotation using chemical agents to enlarge the difference of hydrophobicity, this study was undertaken to examine the feasibility of enlarging the differences in surface work function of coal components to improve the electrostatic separation. Two coal specimens from Alberta having medium ash and low sulfur contents were used. Chemical agents having different physical and chemical properties were investigated in both batch and continuous operation. The results show that either maceral or ash forming mineral separations can be improved by surface treatment with organic chemicals. Improvements of more than 10% were observed. The results also show that some aromatic chemicals are better for coal maceral separation while some aliphatic agents improve ash forming mineral separation.
V‐L‐S multiphase equilibrium in bitumen‐diluent systems
Authors: James Neil E. , Mehrotra Anil K. 
Published: March 2009

AbstractA multiphase flash algorithm is developed for the prediction of V‐L‐L‐S equilibrium. The algorithm uses the Patel‐Teja equation of state for the fluid phases and a separate model, based on vapour pressure, for the solid phase. A novel technique is presented for avoiding the phase disappearance problem commonly encountered in multiphase equilibrium calculations involving multiple fugacity models. The predictions are shown to be in good agreement with the data for several CO2 and hydrocarbons V‐L‐S systems.This paper also presents new experimental data for the solubility of Peace River bitumen in n‐pentane, n‐heptane and n‐octane at atmospheric conditions, and these are compared with the model predictions.
Hydrodynamics of liquid‐liquid dispersion in ejectors and vertical two phase flow
Authors: Mukherjee Dibyendu , Biswas Manindra N. , Mitra Arun K. 
Published: March 2009

AbstractMixing of two immiscible liquids can be conveniently achieved in a liquid‐jet ejector system which utilizes the kinetic energy of a liquid‐jet to simultaneously aspirate and interdisperse the immiscible phases. In such a dispersion process energy dissipation occurs due to friction on the walls of the ejector throat and divergent diffuser, as well as due to mixing and interdispersion of the two phases. The paper deals with the analysis and quantification of these different energy losses.Measurements have also been reported on pressure drop and holdup of two phase liquid‐liquid flow in a vertical column fitted to the ejector system. Correlations have been developed for predicting the irreversible pressure drop (in terms of a two‐phase friction factor) and the holdup on the basis of the physical and dynamic variables of the system. A term ‘degree of mixing’, defined as the ratio of the actual holdup fraction to the homogeneous holdup fraction, has been used to estimate the extent of mixing.
Biofluidization: Application of the fluidization technique in biotechnology
Authors: Schügerl K. 
Published: March 2009

AbstractThe applications of solid/liquid and/or solid/liquid/gas fluidized beds are considered in such areas as environmental biotechnology for the nitrification and denitrification of wastewater, denitrification of drinking water, anaerobic digestion, production of cell mass and primary and secondary metabolites with microorganisms, and cultivation of animal cell lines. Cell mass and alcohol, glutathion, and enzyme production in gas/solid fluidized beds are also considered. The performance and modelling of these reactors are discussed.
Minimum fluidization velocity of binary mixtures
Authors: Chyang Chien‐Song , Kuo Chen‐Chung , Chen May‐Yann 
Published: March 2009

AbstractThe fast defluidization method was used to measure the minimum fluidization velocities of binary systems. Based on the experimental data obtained from the published literature and from this work, different correlations used for predicting the minimum fluidization velocities of binary systems were evaluated and compared.
The imaginary planes method for the calculation of radiative heat transfer in industrial furnaces
Authors: Charette A. , Erchiqui F. , Kocaefe Y. S. 
Published: March 2009

AbstractRadiation is usually the dominant mode of heat transfer in furnace enclosures. The imaginary planes method is one of the new methods for calculating the radiative heat transfer in such systems. In this study, a general procedure was developed for its application in furnace modelling. Various case studies were carried out for a number of furnaces, and the results were compared with those of the zone method. It was found that the new method combines good accuracy with low computation time and appears to be a promising method for the determination of heat flux and temperature distributions within furnace enclosures.
Phase equilibrium in the system water‐hydrogen sulphide: Experimental determination of the LLV locus
Authors: Carroll John J. , Mather Alan E. 
Published: March 2009

AbstractExperimental data are presented for the liquid‐liquid‐vapour (LLV) equilibrium for the system water‐hydrogen sulphide. Conditions ranged from the hydrate‐liquid‐liquid‐vapour quadruple point (29.4°C and 2.23 MPa) to beyond the critical temperature of hydrogen sulphide (100.3°C). The maximum temperature at which three phases can exist is 106.2°C at 9.39 MPa. This is 6°C higher than previously believed.
The structure‐breaking effect on oxygen diffusion coefficients in electrolyte and polyelectrolyte solutions
Authors: Ju Lu‐Kwang , Ho Chester S. 
Published: March 2009

AbstractBy employing a membrane‐covered polarographic oxygen electrode, the oxygen diffusion coefficients and solubilities in aqueous solutions of ammonium chloride, potassium iodide, sodium alginate, sodium carboxymethylcellulose (CMC), and xanthan gum have been measured with a newly developed methodology. Experimental results showed that in all systems studied, oxygen solubilities decrease on addition of solutes. Oxygen diffusion coefficients in aqueous solutions of KI and NH4C1 are found to be higher than that in pure water. In sodium alginate solutions, dilute xanthan solutions, and solutions containing more than 0.3 wt% of CMC, oxygen diffusion coefficients decrease with an increase in polymer concentrations. Interestingly, in dilute CMC solutions and concentrated xanthan solutions containing more than 0.5 wt% of xanthan gum, oxygen diffusion coefficients increase with increasing polymer concentrations, and values exceeding that in pure water are generally observed.
Mass transfer from cylindrical pellets submerged in parallel flowing fluid streams
Authors: Narayan K. A. , Prasad B. K. , Sharma R. N. 
Published: March 2009

AbstractA model is proposed wherein overall mass transfer from single cylinders of benzoic acid placed in parallel flowing water streams depends on different hydrodynamic regimes prevailing along the surfaces of the cylinder. The results for laminar and turbulent conditions are correlated in terms of Sherwood and Reynolds numbers. The mass transfer in the wake region of the cylinder is observed to be significantly different from the boundary layer mass transfer through the lateral surface or the stagnation and boundary layer mass transfer through the leading frontal area.
Determination of potash crystallization kinetics in a laboratory‐scale continuous cooling crystallizer
Authors: Paine K. , Rohani S. 
Published: March 2009

AbstractCrystallization kinetics of KCl in a 21.8L continuous mixed‐suspension‐mixed‐product‐removal (CMSMPR) potash cooling crystallizer are determined using the method of s‐plane analysis (Tavare, 1986). Feed saturated in refined potash, nearly saturated in NaCl and containing 0.75 g of MgSO4 per 100 g of water is cooled from 54°C to 38°C by two concentric cooling coils. The crystallizer is brought to steady‐state and then perturbed by a change in the crysallizer temperature from 38°C to 32°C. Samples are withdrawn every 15 minutes by means of a specially devised sample trap which permits representative sample removal. Samples are sized using sieve‐analysis. The crystallization kinetics are correlated as B° = 49,618 G0,982.
Application of periodic operation to maleic anhydride production
Authors: Lang Xiaosu , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractTwo‐step and multi‐step feed composition cycling of the partial oxidation of butadiene to maleic anhydride have been studied. Multi‐step cycles were created by N2 flushes between steps containing just one reactant. Both production and selectivity to maleic anhydride are decreased over a cycle in this type of periodic operation. Selectivity to furan is increased, however. N2 flushing concentrates production of maleic anhydride in the butadiene step, which may have process advantages.
Thermal stability of morpholine additive in the steam‐water cycle of CANDU‐PHW nuclear power plants
Authors: Gilbert Roland , Lamarre Claude 
Published: March 2009

AbstractThe thermal decomposition of morpholine, an additive used in the steam‐water cycles of nuclear power plants, was studied using a laboratory high‐pressure reactor. The measured decomposition rate constants are 2.67, 8.73 and 21.25 × 10−7s−1at 260, 280 and 300°C respectively. The kinetics were found to be first‐order and the activation energy was 131.9 kJ/mol. Ammonia, ethanolamine, 2‐(2‐aminoethoxy) ethanol, methylamine, ethylamine, ethylene glycol, and acetic and glycolic acids were identified as the major breakdown products. The decomposition route proposed was validated in the field by tracking these breakdown products in water samples taken at Gentilly 2 power plant.
Hydrodynamic studies with foaming and non‐newtonian solutions in bubble columns
Authors: Bukur Dragomir B. , Patel Snehal A. 
Published: March 2009

AbstractExperiments were conducted in 0.05 m ID and 0.23 m ID by 3 m tall bubble columns to study the effect of surfactants and viscosity of liquid medium on gas hold‐up and Sauter mean bubble diameter. The addition of n‐butanol (0.5 and 1 wt.%) to water leads to the formation of foam and consequently produces higher gas hold‐ups. The foam could be eliminated completely with the addition of a sufficient quantity (0.5 wt.%) of carboxymethyl cellulose to the aqueous alcohol solution. In the absence of foam, gas hold‐ups were similar to those obtained with pure liquids. Sauter mean bubble diameters, obtained using the dynamic gas disengagement technique, increase with viscosity of liquid medium.
Effect of interfacial velocity and interfacial tension gradient on momentum, heat and mass transfer
Authors: Hirata Akira , Kawakami Madoka , Okano Yasunori 
Published: March 2009

AbstractThe effect of interfacial velocity and interfacial tension gradient on momentum, heat and mass transfer was studied theoretically. After reviewing current knowledge regarding interfacial velocity effects, the interfacial tension gradient effect is discussed as a numerical solution of the laminar boundary layer equations. The enhancement and suppression of interfacial mobility, and the rates of interphase momentum, heat and mass transfer were related to the Marangoni number. A diagram showing the effect of interfacial tension gradient on momentum, heat and mass transfer is presented.
An adaptive strategy for solving kinetic model concomitant estimation — Reduction problems
Authors: Maria Gheorghe 
Published: March 2009

AbstractIn order to simultaneously estimate the parameters and to reduce a complex kinetic model, an adaptive strategy which combines effective adaptive random search (ARS) and statistical ridge analysis steps is developed. As demonstrated, this strategy can save computational time because the estimation is not repeated with each reduced model. The use of ARS is preferred for highly nonlinear models and cases having multiple parameter constraints, guaranteeing reliability for interactively obtaining the global reduced model parameter solution.
Interfacial viscosity and the stability of emulsions
Authors: Campanelli John R. , Cooper David G. 
Published: March 2009

AbstractA viscous traction interfacial viscometer was constructed to study a mineral oil‐water‐emulsifier system. The effect on interfacial viscosity of the synthetic emulsifiers Span 80 and Pluronic L42 were investigated, along with the bioemulsifier produced by the yeast Torulopsis petrophilum. In the case of the synthetic emulsifiers, it was found that conditions which maximized interfacial viscosity also maximized emulsion stability. The same relation held for T. petrophilum emulsifier once all free fatty acids had been removed from the broth. Emulsion stability was measured by calculating mean diameters, as well as emulsion indices.
Mixing indices in coflowing plane jets: High momentum conditions
Authors: Ng S. , Grandmaison E. W. 
Published: March 2009

AbstractMixing indices describing the completeness of mixing between pairs of plane jets in a triple coflowing jet array have been measured using marker nephelometry. This work is an extension of the results reported by Grandmaison and Zettler (1989) for the case where the centre jet in the array has a higher velocity than the adjacent outer jets. Results include centreline measurements of the static pressure, mean velocity and mean and fluctuation concentration fields, as well as transverse measurements of these properties and concentration intermittency in the near field region where there is significant mixing between the jet streams.
Analysis of an RF induction plasma torch with a permeable ceramic wall
Authors: Mostaghimi Javad , Dostie Michel , Jurewicz Jerzy 
Published: March 2009

AbstractAn analysis is made for an rf plasma torch with a permeable ceramic tube as the contaminant tube. The temperature, flow, and electromagnetic fields in the rf torch are obtained along with the argon flow, the gas and matrix temperatures. The results show that about 80% of the plasma radiation losses are trapped by the ceramic wall. For optimum cooling, a wall with variable thickness is proposed. The results also indicate that argon is not a suitable gas for cooling the permeable wall.
Mixing time of liquid in horizontal stirred vessels with multiple impellers
Authors: Ando K. , Obata E. , Ikeda K. , Fukuda T. 
Published: March 2009

AbstractA method of estimating the mixing time of multiple‐impeller vessels from that of a single‐impeller vessel was proposed. According to the model assumed, the vessel has completely mixed cells separated by impellers, and the exchange flow rate of liquid across two adjacent cells controls the over‐all mixing. The mixing time of multiple‐impeller vessels of various diameters was measured and analyzed on the basis of the model. The range of application of the model was determined experimentally.
Catalytic pyrolysis of almond shells: Influence of temperature and CoCl2 to almond shell ratio
Authors: Font R. , Marcilla A. , Verdú E. , Devesa J. 
Published: March 2009

AbstractTwo different types of equipment were used in this work: an Analytical Flash Pyrolysis Apparatus (AFPA) and a fluidized bed reactor. Using the AFPA a new screening of catalysts impregnated in almond shells has been carried out. Three catalysts — NaOH, MnCl2 and CoCl2 — were selected to study the influence of the impregnated catalyst/almond shell ratio. With MnCl2 and CoCl2, high yields of 2‐furaldehyde were obtained. With CoCl2, the influence of the catalyst/almond shell ratio and the temperature was studied in both types of equipment. The following yields were obtained using the fluidized bed reactor (14.1 g CoCl2/100 g total) within the temperature range 425–610°C: 2‐furaldehyde 6.9–7.2%, acetic acid 5.5–7.2%. Tests have proved that total recovery of the CoCl2 can be achieved.
Recovery of fatty acids by immobilized solvent extraction
Authors: Lav Isaac , Hayward Gordon 
Published: March 2009

AbstractThe use of silicone rubber tubes swollen with solutions of TOPO (trioctyl phosphine oxide) in kerosene as membranes for the recovery of fatty acids from anaerobic digesters was investigated. The flux of acetic and propionic acids was found to increase with the concentration of TOPO when the concentration was low. At very high TOPO concentrations, the flux decreased indicating the existence of an optimum TOPO concentration. The relationship between the flux and concentration of unionized propionic acid did not agree with that expected for pure diffusion. This was due to the reversible reaction between TOPO and propionic acid in the membrane. The flux of propionic acid was measured as a function of time for new membranes and for membranes removed from storage. Rather long times, 70 to 300 hours, were required to achieve steady acid fluxes. This time was required to fully develop the concentration profiles within the membranes.
Unified entry length for newtonian and power–law fluids in laminar pipe flow
Authors: Mehrotra Anil K. , Patience Gregory S. 
Published: March 2009

AbstractA numerical method based on finite differencing is used for investigating the steady–state entrance region laminar flow of incompressible Newtonian and power–law fluids in a circular pipe. The Solution method is validated by comparing the results for Newtonian fluids with those reported in the literature. For power–law fluids, the entry length results are compared with other approximate solutions in the literature. On the basis of the calculated results, a generalized entry length ξ99 = 0.056 is shown to be valid for the laminar flow at Re > 200 of both Newtonian and power–law fluids with 0.75 < n < 1.5.
Analysis of particle trajectories of small particles in flotation when the particles and bubbles are both charged
Authors: Okada Kenji , Akagi Yasuharu , Kogure Masahiko , Yoshioka Naoya 
Published: March 2009

AbstractThe trajectory of a small particle moving to a bubble surface was analyzed by taking into account the effects of surface charges of the bubble and particle and the short range hydrodynamic interaction near the bubble surface, in a flotation process. The particle trajectories obtained theoretically were in good agreement with those obtained by direct observation. Even if the signs of the surface charges of the bubble and particle were the same, the particle adhered to the bubble surface when the net surface force, that is, the sum of the electrostatic force and the van der Waals force, was attractive. Particle capture efficiency, ηS, per bubble was estimated by trajectory analysis and the flotation efficiency, ηT, was calculated. The values of ηT calculated by the particle trajectory analysis were in reasonable agreement with those obtained experimentally. The dependence of particle diameter on ηT was also examined by the particle trajectory analysis.
Formation of fine magnetite particles by oxidation of aqueous suspensions of ferrous hydroxide
Authors: Sada E. , Kumazawa H. , Cho H.‐M. 
Published: March 2009

AbstractFine magnetite particles were prepared by oxidation of aqueous ferrous hydroxide suspensions in a bubble column equipped with an internal concentric draft tube. The oxidation reaction rate could be expressed apparently as zero‐order with respect to the concentration of total ferrous species and first‐order with respect to the concentration of dissolved oxygen. The final particle size generally decreased with increasing reaction rate. The geometric Standard deviation of size‐distribution ranged from 1.20 to 1.35 under the present experimental conditions, and increased with an increase in reaction rate.
Analysis of the lumped and distributed optimal temperature trajectories for packed bed reactors with concentration dependent catalyst deactivation
Authors: Gonzalez‐Velasco Juan R. , Gutierrez‐Ortiz Miguel A. , Gutierrez‐Ortiz Jose I. , Gonzalez‐Marcos Jose A. 
Published: March 2009

AbstractAlgorithms published previously by the authors for solving the problem of spatially uniform and non‐uniform temperature optimal control in tubular fixed bed reactors have been applied to three systems with series catalyst deactivation and different ratios between the activation energies of the main and deactivation reactions. The optimal temperature and conversion trajectories as well as the maximum production obtained have been compared at the same final duration of operation. Systems with slow deactivation obtain maximum production with spatially uniform control, whilst for systems with rapid deactivation the temperature trajectory distributed both in space and time improves the production obtained with lumped control.