bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Distribution and RTD in Trickle Bed Reactors: Experiments and CFD Simulations
Authors: Gunjal Prashant R. , Ranade Vivek V. , Chaudhari Raghunath V. 
Published: July 2010

AbstractHydrodynamics and mixing in trickle bed reactors (TBR) are governed by bed porosity, capillary forces, wetting and non‐uniform distribution at the inlet. In this work, experiments were carried out to study pressure drop, liquid hold‐up and residence time distribution for pre‐wetted and non‐wetted bed. CFD models were developed, in which bed heterogeneity and capillary models were incorporated. Mixing and RTD were simulated using the CFD model. This study was further extended to study the flow mal‐distribution in TBR. Based on these results, current capabilities and limitations of the CFD model were discussed. The model and the results discussed here would be useful to extend application of CFD models for simulating mixing in TBR.
Catalysis of Gas Hydrates by Biosurfactants in Seawater‐Saturated Sand/Clay
Authors: Rogers Rudy E. , Kothapalli Chandra , Lee May S. , Woolsey J Robert 
Published: July 2010

AbstractBiosurfactants catalyzed natural gas hydrate formation in sand/clay packs saturated with seawater. Representative samples from the five possible biosurfactant classifications enhanced hydrate formation rate and decreased hydrate induction time. Biosurfactants increased rates 96% to 288% and decreased induction times 20% to 71% relative to the control. Micellar‐forming rhamnolipid reached a critical micellar concentration at 13 ppm at hydrate‐forming conditions; these micelles migrated readily through a seawater‐saturated sand pack to catalyze hydrate formation in another zone. The type of biosurfactant, in conjunction with specific porous media, help determine massive, dispersed, nodular, or stratified forms of hydrates. Results suggested that minimal microbial activity in ocean‐floor sands can greatly influence gas hydrate formation.
Convergence Promotion in the Wang‐Henke Tridiagonal Matrix Method
Authors: Monroy‐Loperena Rosendo , Flores‐Sánchez Patricia 
Published: July 2010

AbstractIn this work, a modification to the well known and extensively used Tridiagonal Matrix Method, proposed since 1966 by Wang and Henke (1966), for simulating vapour‐liquid multi‐stage distillation problems is proposed for promoting the convergence of the original iterative process. The modification, which involves the incorporation of Broyden's method for accelerating convergence based on adjustment of the tear variables, solves the vapour‐liquid multi‐stage distillation problems in a more efficient way. Two promotion schemes are proposed, one uses as the tear variables the temperature and vapour flow profiles and the other uses only the temperature profile. The two promotion schemes are compared to the original iteration scheme proposed by Wang and Henke. Results are reported for distillation and reboiled‐absorption processes.
Non‐Linear Predictive Control of a Three‐Phase Catalytic Reactor
Authors: Costa Aline C. , Filho Rubens Maciel 
Published: July 2010

AbstractIn this work, the predictive control of a three‐phase catalytic reactor is considered. A predictive control algorithm, which has a non‐linear internal model represented by functional link networks, is proposed. This network structure has been shown to have a good non‐linear approximation capability, with the advantage that the estimation of its weight is a linear optimization problem. The results show the potential of the proposed procedure when it is applied to the 2‐methyl‐cyclohexanol production process, which is a non‐linear, distributed parameter and time‐varying process, typical of many important industrial systems.
Hydrocyclone Performance with Complex Oil‐Water Emulsions in the Feed
Authors: Belaidi Abdelhafid , Thew Martin T. , Munaweera Sampath J. 
Published: July 2010

AbstractSeparation performance of an oil‐water hydrocyclone depends very much on the physical properties of the feed emulsion or dispersion. These properties can be influenced by numerous factors, particularly water cut and the type of emulsion.In this exploratory work, the effects of water cut and flowrate on de‐watering capabilities of a hydrocyclone with a complex emulsion in the feed line are investigated. Two flow rates of 25 and 35L/min were studied and the water cut was varied from about 8 to 65%. For each case separation, efficiency was measured, the emulsion characterized and its stability checked for the three hydrocyclone streams. Drop size distribution was also examined. Comparison of performance with a simple emulsion was also made.
Synthesis and Analysis of Triphenylamine: A Review
Authors: Manifar Touraj , Rohani Sohrab 
Published: July 2010

AbstractIn this paper, synthesis and characteristic of arylamine‐type molecules, particularly triphenylamine are discussed. An overview of the physical properties and chemical characteristics of these types of molecules is provided. Different synthesis methods and mechanisms involved for the production of these molecules and their analysis byHPLCare presented. Finally, a brief note about their purification is presented.
Measurement and Prediction of the Solubility of Stearic Acid Polymorphs by the UNIQUAC Equation
Authors: Mirmehrabi Mahmoud , Rohani Sohrab 
Published: July 2010

AbstractThe solubility of stearic acid polymorphs B and C in methanol, 2‐butanone, decane and hexane was measured using a precise gravimetric method. Stearic acid is a molecule with 18 carbons that is highly nonideal in solutions and experimental data show strong deviations from the solubility prediction for ideal systems. It is soluble in both polar and nonpolar organic solvents. From experimental solubility, data the solvent mediated polymorphic transition temperature was found around 30°C. From thermal analysis, temperature and heat of transition from form B to form C and also heat of fusion of form C were found to be 49°C, 20 J/g and 240 J/g, respectively. From experimental solubility data the binary parameters of the universal quasi‐chemical (UNIQUAC) model, for stearic acid were calculated. The UNIQUAC solubility predictions compared very closely with the experimental data.
A General Correlation for the Rise Velocity of Single Gas Bubbles
Authors: Rodrigue Denis 
Published: July 2010

AbstractA correlation for the terminal rising velocity of a single gas bubble in an infinite Newtonian fluid is proposed. The model is an extension to high Reynolds numbers of a model developed recently by the author (Rodrigue, 2001a). This new equation, which is explicit in velocity, is able to predict the velocity for any bubble volume in any Newtonian fluid.
Analysis of Pre‐filter Based Closed‐loop Control‐relevant Identification Methodologies
Authors: Shreesha C , Gudi Ravindra D. 
Published: July 2010

AbstractControl‐relevant identification strategies have been variously proposed for open loop model building. In this paper, issues related to control‐relevant model building in closed‐loop schemes are discussed. Various important aspects such as pre‐filter design and plant friendliness of the perturbation signals have been examined. Simulations involving representative problems have been considered from chemical engineering literature to highlight the applicability of the proposed methods.
Simulation and Modeling of Vegetable Market Wastes Pyrolysis Under Progressive Deactivation Condition
Authors: Ray Ruby , Bhattacharya Pinaki , Chowdhury Ranjana 
Published: July 2010

AbstractThe pyrolysis behaviour of predried vegetable market waste has been investigated using TGA within the temperature range 523 to 923 K under inert atmosphere and a comparison has been made with other lignocellulosic materials in order to point out the difference between the pyrolysis of nearly homogeneous and perfectly mixed heterogeneous biomass. Kinetic parameters of the pyrolysis material have been evaluated from the simulation of the TG data. A reaction mechanism involving two parallel 1st order reactions evolving gaseous products lumped as volatiles and solid products lumped as char has been proposed for prediction of rate constants as a function of normalized fractional change. Four kinetic models incorporating the effect of deactivation have been used for this purpose. In another attempt, using concentration independent model of solid deactivation, simulation has been carried out to predict concentration time history of the system components as well as quantitative change of rate constants with the propagation of time.
MHD‐Buoyancy Aiding and Opposing Flows with Viscous Dissipation Effects from Radiate Vertical Surfaces
Authors: Duwairi H. M. , Damseh Rebhi A. 
Published: July 2010

AbstractThe combined effects of forced and natural convection heat transfer in the presence of transverse magnetic field form a vertical surfaces with radiation heat transfer is studied. The buoyancy aided flow and the buoyancy opposing flows are investigated with viscous dissipation effects included in the governing equations. It is found that four parameters can describe the problem under consideration, the mixed parameter, χ, the radiation‐conduction parameter, Rd, the magnetic field parameter, Ha2x/Rex, and the Eckert number, Ec. The local wall shear stresses and the local Nusselt number variations are drawn for different dimensionless groups.
Reaction Kinetics of Decomposition of Acidic Sodium Chlorite
Authors: Deshwal Bal Raj , Jo Hang‐Dae , Lee Hyung‐Keun 
Published: July 2010

AbstractThe decomposition of sodium chlorite was studied in a well‐stirred reactor in a pH range of 2—3 and a temperature range of 15—35°C varying the chlorite concentration. The reaction rate was evaluated by analyzing the consumption of chlorite iodometrically. The rate law was established. Reaction was found to be of the first order with respect to both chlorite and acid concentration. Temperature dependence of the reaction was also studied and pre‐exponential Arrehenius parameter and activation energy were determined. The optimum conditions to generate chlorine dioxide from sodium chlorite are also highlighted.
Liquid Holdup and Pressure Drop Determination in Structured Packing with CFD Simulations
Authors: Raynal Ludovic , Boyer Christophe , Ballaguet Jean‐Pierre 
Published: July 2010

AbstractIt is discussed how Computational Fluid Dynamics (CFD) can be used for hydrodynamics calculations within structured packings. Three dimensional (3D) simulations, in which the influence of mesh size and turbulence models were tested, have been carried out for dry pressure drop determination. Two dimensional (2D) Volume of Fluid gas‐liquid flow simulations have been used for liquid holdup determination. Numerical results are compared to tomographic liquid holdup measurements. Then, a comparison with data from a gas treatment pilot plant shows that wet pressure drop can be predicted by combining these two types of information (dry pressure drop and liquid holdup).
Modelling Heterogeneous Slurry Flows at High Velocities
Authors: Gillies Randall G. , Shook Clifton A. , Xu Jihuai 
Published: July 2010

AbstractExperiments have been conducted with sand slurries of median diameter 0.09 mm and 0.27 mm in a laboratory test pipeline 0.103 m in diameter. In addition to pressure gradient measurements as functions of mean velocity and in‐situ solids concentration, concentration and velocity profiles have been obtained. The measurements show that the pipeline friction is lower than expected at high velocities. This deviation is of the type that has been predicted in recent theoretical work by Wilson and coworkers. A correlation for the slurry friction at high velocities has been obtained. This correlation has been used to modify the model for predicting friction of heterogeneous slurries at velocities above the deposition condition.
Substitution du chrome dans les bains de passivation de l'acier galvanisé
Authors: Zazoua Ali , Samar Mohamed Elhadi , Kherrat Rochdi , Azzouz Noureddine 
Published: July 2010

AbstractIl est bien connu que le chrome possède une haute toxicité et des effets cancérigènes. Son remplacement constitue donc une priorité majeure. De ce fait, l'objectif de cette étude est la recherche d'un produit de substitution non toxique ou le moins toxique possible. A cet effet, nous avons effectué des essais comparatifs de performance (vis‐à‐vis du chrome) de deux électrolytes, un hétéropolysiloxane (HPS) et un molybdate. Les résultats obtenus montrent, en plus du caractère non toxique, une très nette supériorité de l'HPS par rapport au chromate et au molybdate au point de vue protection contre la corrosion. Le revêtement de conversion par le molybdate est de moindre qualité anticorrosion, à la fois par rapport à l'HPS et par rapport au chromate.
Carbonation of Magnesium Silicate Minerals: An Experimental Study
Authors: Jia Lufei , Anthony Edward J. , Lin Weigang , Ruan Yuhong , Gora Darius 
Published: July 2010

AbstractCO2 sequestration by magnesium silicate mineral is the only known process that can permanently store CO2 using a natural feedstock that exists in sufficient quantities to be used practically. Transporting large amounts of mineral over long distances is uneconomical. For Canada to benefit from such a process, identification of suitable Canadian magnesium silicate mineral deposits is crucial. Only carbonation under pressure in NaCl and NaCl/NaHCO3 solutions results in high Mg conversions (40–80%). Among the minerals examined in this study, the serpentines reacted most easily, and peridotite was the most difficult to carbonate. Increasing carbonation pressure to very high levels reduced the degree of carbonation as hydrolysis reactions became competitive with the carbonation process.
A Comparative Study on Acid Leaching of Low Grade Manganese Ore Using Some Industrial Wastes as Reductants
Authors: Ismail Adel A. , Ali Essam A. , Ibrahim Ibrahim A. , Ahmed Mohamed S. 
Published: July 2010

AbstractLocal pyrolusite ore from Om‐Bogma, Sinai, has been treated by sulfuric acid leaching process using either sawdust (C6H10O5)n or lactose (C12H22O11) as reducing agent to produce manganese sulfate. The manganese recoveries were 92.5 and 90.5% at sawdust and lactose respectively.
Numerical Simulation of Pollutant Formation in Precalciner
Authors: Huang Lai , Lu Jidong , Wang Shijie , Hu Zhijuan 
Published: July 2010

AbstractFor cement plants, great attention is being paid to the emission of the pollutant gases, especially NO, CO and CO2. Precalciner is an important equipment in a cement plant in that it can reduce not only the heat loading of rotary kiln but also the NO emission because of its relative low operating temperature. In this paper, the mechanisms for the formation of NO and CO are analyzed and a numerical simulation technique is applied to model the coal combustion, raw material decomposition and concentration distribution of the pollutant gases in a full scale DD‐PRC (dual combustion and denitrator process precalciner). The predicted results agree well with the measured data.
The Effects of Screw Geometry on the Pumping Efficiency of Micro‐Screw Pump
Authors: El‐Sadi Haifa , Esmail Nabil 
Published: July 2010

AbstractThe design of a novel micro‐screw pump for viscous fluid is described. The device consists of a rotating screw in the centre of the channel, connected with a shaft and micro motor. The objective of this research is to investigate the effect of using various screw geometries on the pump performance. Theoretical analysis by finite volume simulations is carried out to study the influence of pitch, diameter of the screw and the thread (flight depth) to evaluate the optimal dimensions for the pump and to obtain the maximum flow rate. When the screw rotates, a net force is transferred to the fluid due to the differential pressure on the depth of the thread and pressure gradient along the screw axis, thus causing the fluid to displace. The three‐dimensional simulations indicate a gradual increase of the average velocity with increasing the screw diameter. The maximum average velocity can be obtained when the ratio between the pitch and screw diameter (pi/d) is 0.6. Effective pumping is achieved by increasing the thread and pitch at maximum screw diameter. The numerical simulation has been validated experimentally.
Design Considerations for Plate and Frame Ultrafiltration Modules by Computational Fluid Dynamics Analysis
Authors: Dal‐Cin Mauro M. , Darcovich Ken , Caza Daniel 
Published: July 2010

AbstractPressure and flow maldistributions were studied in a full‐scale industrial plate and frame ultrafiltration module, operating in a Z flow pattern, for the recovery of used motor oils. Solutions were obtained using (1) a three‐dimensional solution of the Navier‐Stokes equation using computational fluid dynamics and (2) Bernoulli's equation and a momentum balance in one dimension. Fluid decelerations and accelerations generated pressure increases and decreases in the distributor and collector, respectively, biasing the flow distribution to the last channel. Several modifications to the original design were evaluated; the most effective was larger distributor and collector diameters, which greatly improved the uniformity of the flow distribution and transmembrane pressure, and reduced the overall pressure drop in a bank. A variable diameter distributor and collector module was designed using the 1‐D model. Flow distribution was significantly improved but also yielded an undesirable overall higher pressure drop and a pressure maldistribution in the bank. The maldistribution of the main inlet manifold to the distributors in the first bank was strongly dependent on the module design. The flow distribution across the width of a channel became uniform within a short distance, essentially eliminating the need to consider this design aspect any further. Flows at the bank outlets, and hence inlets of the following bank, showed uniform lateral distribution in all cases, suggesting that future modelling work can be limited to a fraction of the module width, based on symmetry, in order to gain computational efficiency.
A New Method of Eddy Diffusivity Calculation for Droplets of a Venturi Scrubber
Authors: Rahimi A. , Fathikalajahi J. , Taheri M. 
Published: July 2010

AbstractAn analytical model using eddy diffusivity is applied for predicting droplet concentration distribution and liquid film formation in a Venturi scrubber. By comparing experimental data of film formation reported in literature (Viswanathan et al., 1984) and the results obtained from this model, a semi‐empirical correlation for liquid droplets eddy diffusivity is obtained. The validity of this correlation is confirmed by obtaining good agreement between theoretical and experimental data of droplet concentration distribution and film formation in a Venturi scrubber (Viswanathan, 1998; Viswanathan et al., 1984).
Secondary Cracking of C4 Hydrocarbons from Heavy Oil Catalytic Pyrolysis
Authors: Meng Xianghai , Xu Chunming , Gao Jinsen 
Published: July 2010

AbstractFor C4 hydrocarbons from heavy oil catalytic pyrolysis, the cracking behaviours on catalyst CEP‐1 and quartz sand were investigated in a confined fluidized bed reactor. C4 hydrocarbons show a good cracking ability on CEP‐1, and butene is easier to convert than butane. Only at high reaction temperatures can butane present a good cracking ability. On catalyst CEP‐1, C4 hydrocarbons can undergo not only cracking reactions, but also such reactions as hydrogen transfer, polymerization and aromatization. The conversion of C4 hydrocarbons thermal pyrolysis is high, indicating that free radical reactions play an important part in the secondary cracking of C4 hydrocarbons. The product yields of C4 hydrocarbons pyrolysis on quartz sand are usually lower than those on catalyst CEP‐1. For both catalytic pyrolysis and thermal pyrolysis of C4 hydrocarbons, the selectivity of propene is higher than that of ethene.
Studies on Phenol‐Formaldehyde Gel Formation at a High Temperature and at Different pH
Authors: Banerjee Ranjan , Patil Kiran , Khilar Kartic C. 
Published: July 2010

AbstractGel formation characteristic of dilute phenol‐formaldehyde solution in water is studied at an elevated temperature near 140°C. It is experimentally found that at a temperature range of 135°C to 140°C, a solution containing 3.0% phenol with the phenol‐formaldehyde mole ratio 1.0:3.5 forms a gel in the pH range of 9.6 to 12.0. The minimum gelling time is observed at a pH value of 10.4. The gel formation is found to be strongly dependent on the pH at this elevated temperature. An explanation for the gelling behaviour is presented, which is based on an optimum ion concentration of Na+ to initiate the tri‐methylol formation. It is hypothesized that the gel formation begins when concentration of tri‐methylol phenol attains a threshold concentration value. Experimental observations and a kinetic analysis provide support for this hypothesis.
Real‐time Dynamic Optimization of Non‐linear Batch Systems
Authors: Peters Nathaniel , Guay Martin , Dehaan Darryl 
Published: July 2010

AbstractIn this paper, a methodology for designing and implementing a real time optimizing controller for non‐linear batch processes is discussed. The controller is used to optimize the system input and state trajectories according to a cost function. An interior point method with penalty function is used to incorporate constraints into a modified cost functional, and a Lyapunov‐based extremum seeking approach is used to compute the trajectory parameters. Smooth trajectories were generated with reduced computing time compared to many optimizations in literature. In this paper, the theory is applied to general non‐flat non‐linear systems in a true on‐line optimization.
Simultaneous Measurement Bias Correction and Dynamic Data Reconciliation
Authors: Bai Shuanghua , Mclean David D. , Thibault Jules 
Published: July 2010

AbstractThe presence of measurement bias and random noise significantly deteriorates the information quality of plant data. Data reconciliation techniques for steady‐state processes have been widely applied to processing industries to improve the accuracy and precision of the raw measurements. This paper develops an algorithm for simultaneous bias correction and data reconciliation for dynamic processes. The algorithm considers process model error as an important contributing factor in the estimation of the measurement bias and process state variables. It employs black‐box models for the process as would be done when phenomenological models are difficult or impractical to obtain. Simulation results of a distillation column demonstrated that this algorithm effectively compensates constant and non‐constant measurement biases yielding much improved reconciled values of process variables. It has computational advantages over previously proposed algorithms based on non‐linear dynamic data reconciliation because an analytical solution is available when using linear process models to approximate the process.
A Fully Continuous Supercritical Fluid Extraction System for Contaminated Soil
Authors: Ryan M. , Stiver W. H. 
Published: July 2010

AbstractA fully continuous lab scale supercritical fluid extraction system has been designed, built and tested. The system continuously pumps carbon dioxide under supercritical conditions and soil slurry into a counter‐current contacting column. Delhi Loamy Sand, spiked with approximately 10 mg/g of naphthalene, was used as the testing soil. The soil slurry ranged from 0.0028 g dry soil per g slurry to 0.072 g/g. The operating temperature was 43°C and the operating pressure was 7.7 MPa. Near steady state, fully continuous flow was achieved with runs lasting as long as 2 h. All carbon dioxide samples contained measurable quantities of naphthalene and the measured mass transfer coefficients were as high as 4.6×10−4 s−1.