bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of silver cementation yield in fixed bed reactor using factorial design and central composite design
Authors: Yahiaoui I. , Aissani‐Benissad F. , Aït‐Amar H. 
Published: July 2010

AbstractThis work deals with cementation of silver onto iron grid in fixed bed reactor. The influence of several parameters is studied namely: initial concentration of silver [Ag+]0, flow rate, solution pH, and mass of iron. Moreover, their influence on the yield of the reaction of cementation is investigated statistically by the experimental design in view of industrial application. The estimation and the comparison of the parameter's effects are realised by using two‐level factorial design. The analysis of these effects permits to state that the most influential factor is the mass of iron with an effect of (+5.642), the second in the order is the initial concentration of silver ions (Ag+) with an effect of (+4.005), the third is the flow rate of the electrolytic solution with an effect of (+3.824). A central composite design methodology is employed to determine the optimum conditions for a silver cementation yield onto iron grid. For this end, the experimental results were approximated by a second‐order model as well as the surface contour plots and surface responses are drowned. The optimal conditions found for initial silver concentration, such as a flow rate, pH of the solution and mass of iron, are respectively: 21.25 mg/L, 4.43 L/min, 3.6 and 50 g. Under these conditions, the obtained silver cementation yield is 96.851%.
Interfacial area for concurrent gas–liquid upflow through packed bed
Authors: Raghavendra Rao A. V. , Kishore Kumar R. , Sankarshana T. , Khan Ahamed 
Published: July 2010

AbstractInterfacial area is measured for a large range of column packing (Raschig rings, Intalox saddles, and two sizes of spheres) for concurrent gas–liquid upflow through packed bed covering bubble, pulse and early spray flow regimes using air–aqueous sodium sulfite solution. It was observed that the interfacial area increased with increase in fluids flow rate and decreased with the increase in the particle size for the same type of packing. A correlation (3 ≤ Rel ≤ 165, 0.5 ≤ Reg ≤ 210) was developed using present data (120 data points) and literature data (100 data points), which predict the interfacial area with an rms deviation of 16%.
Retrofit of absorption heat pumps into manufacturing processes: Implementation guidelines
Authors: Bakhtiari Bahador , Fradette Louis , Legros Robert , Paris Jean 
Published: July 2010

AbstractIntegration of absorption heat pumps (AHP) in industrial processes has not yet been fully exploited due to the lack of clear implementation guidelines for this technology. In this work, a systematic methodology for the integration of AHPs in a process has been developed and is presented. Guidelines are formulated for the proper selection of heat sources and sinks that will maximise the benefit derived from heat pumping while respecting process constraints and operating requirements of the AHP. The principles of AHP operation and its efficient process integration are thus described. The methodology relies on data extracted from a Pinch Analysis of the plant. The advantages and outputs of the methodology are illustrated using an AHP implementation in a Kraft pulping process. Two realistic implementation options are presented along with their detailed design and preliminary economic evaluation.
Modelling and control of different types of polymerization processes using neural networks technique: A review
Authors: Noor R. A. Mat , Ahmad Z. , Don M. Mat , Uzir M. H. 
Published: July 2010

AbstractPolymerization process can be classified as a nonlinear type process since it exhibits a dynamic behaviour throughout the process. Therefore, it is highly complicated to obtain an accurate mechanistic model from the nonlinear process. This predicament always been a “wall” to researchers to be able to devise an optimal process model and control scheme for such a system. Neural networks have succeeded the other modelling and control methods especially in coping with nonlinear process due to their very conciliate characteristics. These characteristics are further explained in this work. The predicament that is encountered by researchers nowadays is lack of data which consequently lead to an imprecise mechanistic model that scarcely conforms to the desired process. The implementations of the neural network model not only restrict to polymerization reactor but to other difficult‐to‐measure parameters such as polymer quality, polymer melts index and mixture of initiators. This work is aimed to manifest ascendancy of neural networks in modelling and control of polymerization process.
A kinetics study in CSTR using simultaneous temperature scanning and composition modulation: The alkaline hydrolysis of ethyl acetate
Authors: Jaree Attasak , Nuammaneerat Chonthida 
Published: July 2010

AbstractThis work presents a new technique for reaction kinetic studies of liquid phase reactions in a CSTR. By simultaneously varying the reaction temperature (temperature scanning—TS) and reactant feed concentration (composition modulation—CM) while recording the output concentration, the technique allows, through the least‐square fitting of computer‐generated model data to the experimental time‐series, to obtain from a single experiment the reaction orders as well as both Arrhenius parameters. The alkaline hydrolysis of ethyl acetate was chosen to illustrate the technique, assuming a rate law in the form of a simple power law. The set of parameters that resulted in the minimum sum of squared errors was selected. These values were very close to those reported in literature. The technique saves much time and experimental resources.
On MHD heat and mass transfer over a moving vertical plate with a convective surface boundary condition
Authors: Makinde O. D. 
Published: July 2010

AbstractIn this paper, the magnetohydrodynamics (MHD) boundary layer flow with heat and mass transfer over a moving vertical plate in the presence of magnetic field and a convective heat exchange at the surface with the surrounding has been studied. The similarity solution is used to transform the system of partial differential equations, describing the problem under consideration, into a boundary value problem of coupled ordinary differential equations, and an efficient numerical technique is implemented to solve the reduced system. The results are presented graphically and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters.
Computer calculation of heat capacity of natural gases over a wide range of pressure and temperature
Authors: Dranchuk P. M. , Abou‐Kassem J. H. 
Published: July 2010

AbstractThis paper presents a method whereby specific heats or heat capacities of natural gases, both sweet and sour, at elevated pressures and temperatures may be made suitable to modern day machine calculation. The method involves developing (1) a correlation for ideal isobaric heat capacity as a function of gas gravity and pseudo reduced temperature over the temperature range of 300 to 1500 K and (2) a mathematical equation for the isobaric heat capacity departure based on accepted thermodynamic principles applied to an equation of state that adequately describes the behavior of gases to which the Standing and Katz Z factor correlation applies. The heat capacity departure equation is applicable over the range of 0.2 ≤ Pr ≤ 15 and 1.05 ≤ Tr ≤ 3. The significance of the method presented here lies in its utility and adaptability to computer applications.
Hydrogenation of carbon dioxide on iron catalysts doubly promoted with manganese and potassium
Authors: Lee Jyh‐Fu , Chern Wen‐Shing , Lee Min‐Dar , Dong Teng‐Yuan 
Published: July 2010

AbstractThe effect of addition of manganese and potassium promoters onto iron catalysts for hydrogenation of carbon dioxide was investigated. Catalyst characterizations were performed using BET surface area measurement, carbon monoxide chemisorption, temperature‐programmed reduction and Mössbauer spectroscopy. It was noted that metallic iron catalysts were carburized to θ‐Fe3C and χ‐Fe5C2 as well as oxidized to Fe3O4 during the course of reaction. The promotional effect of manganese was reflected in stabilization of catalytic behavior owing to a higher resistance to bulk oxidation. However, the distribution of hydrocarbon products did not change significantly in the presence of manganese promoter. With further addition of potassium promoter, the bulk phase was more likely to transform to carbides, and the selectivity toward olefins and long‐chain hydrocarbons was remarkably enhanced.
A study of the pressure balance around the loop of a circulating fluidized bed
Authors: Rhodes M. J. , Laussmann P. 
Published: July 2010

AbstractPressure measurements around the loop of a circulating fluidized bed with 152 mm ID riser and L‐valve fecuer were analysed to determine the effect of operating parameters (superficial gas velocity in the range 2.2 ‐ 4.0 m/s, solids circulation flux in the range 5 ‐ 50 kg/m2 · s and solids inventory, in the range 80 ‐ 180 kg) on the components of the pressure balance. The riser pressure drop, and hence, riser solids holdup were not affected by changes in the inventory of solids in the system, provided riser superficial gas velocity and solid circulation flux were held constant. The mean suspension concentration in the riser was found to be directly proportional to the ratio of solids flux to superficial gas velocity (G / U) in the riser.
Optimal stationary states in thermalhydraulics: Total reflux condensation
Authors: Venugopalan D. , Girard R. , Kirkaldy J. S. 
Published: July 2010

AbstractReflux condensation in a weakly fluctuating stationary mode can be classified with dissipative. pattern‐forming structures. In those states which possess a single phase region topping the two‐phase region the steady state conservation equations do not uniquely determine the length of the two‐phase column. This degeneracy can be removed in accord with the principle of maximum path probability by optimizing the rate of entropy production. Models of reflux condensers with one and several cooling jackets which possess a maximal state are presented. The model predicts the general features of the experimental data without recourse to empirical correlations.
Modeling of solid—liquid adsorption: Effects of adsorbent loads on model parameters
Authors: Leitão Anabela , da Conceição Euridice , Santos Rosalinda , Rodrigues Alirio 
Published: July 2010

AbstractThe adsorption of cobalt phthalocyanine dye onto activated carbon in a continuous stirred tank adsorber was studied.The variables investigated were: adsorbent mass, adsorbent particle size and fluid flowrate.Several models based on film, pore and surface diffusion were constructed and fitted to the experimental data.Experimental results showed: (i) the increasing importance of the film mass transfer resistance for increasing adsorbent loads; (ii) the increasing importance of the surface diffusion mechanism for increasing adsorbent loads; and (iii) the better discrimination among different models for higher adsorbent loads and lower flowrate.
Adsorption of water vapour on activated alumina. I —‐ equilibrium behaviour
Authors: Desai R. , Hussain M. , Ruthven D. M. 
Published: July 2010

AbstractEquilbrium isotherms are reported for adsorption of water vapour on several different activated alumina adsorbents. The experimentally measured isotherms represent the sum of the contributions from water vapour held in several ways but these contributions can be resolved by detailed analysis. The individual isotherms conform closely to simple idealized models (Langmuir for chemisorption, BET for physisorption), thus providing a rational basis on which to compare different samples and the effects of different regeneration procedures. The apparent complexity in the behaviour of these systems arises from the superposition of the different contributions, the relative importance of which depends upon the nature of the sample and the regeneration conditions. By contrast, the behaviour of the resolved isotherms is relatively straightforward.
Adsorption on activated alumina. II — kinetic behaviour
Authors: Desai R. , Hussain M. , Ruthven D. M. 
Published: July 2010

AbstractThe kinetics of adsorption of water vapour, dimethyl ether, isobutylene, and methanol on activated alumina have been investigated by gravimetric uptake rate and breakthrough curve measurements. Intraparticle diffusivities were determined by matching the experimental response curves to appropriate theoretical models. At low concentration the kinetic‐behaviour is straightforward. The sorption rate is controlled by macropore diffusion with contributions from both the Knudsen and molecular mechanisms, depending on the conditions. For water vapour at higher pressures beyond the point of inflection of the isotherm there appears to be a significant contribution from surface diffusion.
Characterization of the reactivity of limestones with SO2 in a fluidized bed reactor
Authors: Garciá‐Labiano F. , Adánez J. , Rubiera F. , Fuertes A. B. , Pis J. J. 
Published: July 2010

AbstractThe reaction between SO2 and calcined limestone particles has been studied in a fluidized bed combustor. Measurements of sorbent reactivity with SO2 were made for small batches of limestone injected into the combustor. Simultaneous continuous combustion of bituminous coal provided conditions like those of a boiler for study of the sulphation reaction. A semi‐empirical rate model of the CaO‐SO2 reaction has been developed. External mass transfer of SO2, diffusion within the particles and chemical reaction are taken into account. The limestone reactivity with SO2 is characterized by two parameters which are dependent on the temperature and sorbent particle size.A model for predicting the limestone requirements in a fluidized bed boiler has been developed. Parameters from the batch experiments are included. The predictions for sulfur retention agree with the experimental results. In addition, effects of operating conditions (gas velocity, recycle, limestone particle size) on the retention of SO2 were simulated using the model.
The movement of solids through flighted rotating drums. Part II solids‐gas interaction and model validation
Authors: Sherritt Richard G. , Caple Rod , Behie Leo A. , Mehrotra Anil K. 
Published: July 2010

AbstractA residence time model for a rotating drum with lifting flights which includes axial displacement of airborne particles due to the drag of the gas stream has been developed in Part I of this study (Sherritt et al., 1993). Because the particles fall in curtains, the equations for single particle drag overestimated the effect of the gas stream on the displacement of the falling particles. In this paper, large scale wind tunnel experiments, which involved pouring a curtain of particles into a gas stream, indicated that the shielding effect of the curtain could be represented by a lower‐than‐average gas velocity within the curtain. The magnitude of the curtain shielding effect is related to the flight discharge rate, the fall distance and the flight length. Incorporating the results of the experiments into the residence time model provides a significant improvement on the effect of the gas velocity, and hence the best model available, especially for industrial‐scale equipment.
Measurement of gas and liquid flows in stirred tank reactors with multiple agitators
Authors: Manikowski M. , Bodemeier S. , Lübbert A. , Bujalski W. , Nienow A. W. 
Published: July 2010

AbstractThe gas flow in a 3:1 aspect ratio vessel agitated by triple Rushton turbines has been measured by an ultrasound Doppler probe and by means of residence time studies. Strong recirculation around each impeller is found which fits in well with the compartmentalisation found in earlier liquid mixing studies. Surprisingly, when two axial A315 impellers above a Rushton turbine were used, gas recirculation around each impeller was still found. Study of the liquid phase mixing by a decolourisation technique confirmed that the gas flow essentially destroyed the strong axial liquid flow expected. Indeed, even under unaerated conditions, compartmentalisation was found between each impeller.
Effect of restrictive diffusion on hydrodesulfurization of heavy residue oils over CoMo/Al2O3
Authors: Chen Yu‐Wen , Tsai Ming‐Chang , Li Chiuping , Kang Ben‐Chang 
Published: July 2010

AbstractThe effect of the ratio of reactant molecular diameter to catalyst pore diameter (λ) on the restrictive diffusion under hydrodesulfurization (HDS) reactions of heavy residue oils over CoMo/Al2O3 catalysts was investigated. A series of Al2O3 with various pore structures were used as supports of CoMo sulfide. The HDS reaction was carried out in a semi‐batch Carberry type reactor at 648 K and 10.3 MPa. Two empirical correlations for restrictive diffusion under HDS reaction conditions were developed depending on the value of λ. The results showed that the restrictive diffusion effect under HDS reaction conditions is severe for the lower values of λ. However, this effect seems not prominent for higher values of λ. The order of the magnitude of the effective diffusivity was in the range of 10−6‐10−7 cm2/s for the sulfur‐containing compounds of residue oil in CoMo/Al2O3 catalysts at 648 K.
Effect of Technological Factors on Electrochemical Hydrogenation of Lignin
Authors: Zhang Jianan , Zhang Xiaoyong , Xie Dongming , Liu Dehua , Li Zuohu 
Published: July 2010

AbstractLignin properties were improved by electrochemical hydrogenation. Various technological factors, such as cathode materials, temperature and concentrations of water, solvent, substrate, on the electrochemical hydrogenation of lignin in divided electrolytic cell were studied. The results showed that the hydrogen content (H %) and ratio of hydrogen to carbon (H/C) of hydrogenated lignin (HL) increased by 1.7 % and 0.04, respectively, and the softening point (SP) decreased by 24°C in comparison with lignin raw material. It was feasible for lignin to be electrochemically hydrogenated.
Flocculation Monitoring: Focused Beam Reflectance Measurement as a Measurement Tool
Authors: Blanco A , Fuente E , Negro C , Tijero J 
Published: July 2010

AbstractA methodology to study flocculation processes and floc properties using a non‐imaging scanning laser microscope is presented in this paper. This methodology allows us to study floc stability and resistance to shear forces, re‐flocculation tendency and reversibility of the flocs. Furthermore, optimal dosage of any polymer and the associated flocculation mechanism can be determined. In order to illustrate the technique, some examples applied to flocculation in papermaking are described. Although in this paper all the examples have been applied to papermaking, the developed methodology can be used in any process in which flocculation phenomena is involved.
Determination of the Optimum Conditions for Zinc Extraction from Ore Containing Sphalerite by HCL Solutions
Authors: Ata Osman Nuri , Yeşilyurt Murat , Çolak Sabri , Beşe Ayşe Vildan 
Published: July 2010

AbstractThe Taguchi method has been used to determine optimum conditions for the zinc and iron extraction from ore containing sphalerite by HCI solutions. After determining the important parameters in extraction efficiency, an experimental series with two steps was carried out. The optimum conditions for the first series of experiments were found to be reaction temperature 90°C, solid‐to‐liquid ratio 0.091 g/mL, acid concentration 25 mass%, particle size ‐100+200 mesh, stirring speed 300 rpm and reaction time 120 min. Under these conditions, zinc extraction efficiency from ore was approximately 60%. The optimum conditions for the second series of experiments were found to be reaction temperature 90°C, acid concentration 32.5 mass%, solid‐to‐liquid ratio 0.1 g/mL, and reaction time 180 min. Under these conditions, zinc extraction efficiency from the ore was approximately 100%. Alternative working conditions reducing the total cost were also determined.
Measuring Volumetric Phase Fractions in a Gas‐Solid‐Liquid Stirred Tank Reactor Using an Impedance Probe
Authors: Brunazzi Elisabetta , Festa Umberto Di , Galletti Chiara , Merello Cesare , Paglianti Alessandro , Pintus Sandro 
Published: July 2010

AbstractA probe based on the measurement of the electrical impedance has been developed to determine the phase hold‐ups in gas‐solid‐liquid stirred tank reactors. The idea was to take advantage of the complex nature of electrical impedance to derive two independent data (conductance and capacitance) from one measurement. Particular attention has been paid to the calibration of the probe and two semi‐empirical equations have been given to relate measurement to hold‐ups. Subsequently, experiments were performed on three‐phase and two‐phase (gas‐liquid and solid‐liquid) systems and the results have been critically analysed.
Diagnosis of Solid Distribution in Vessels Stirred with Multiple PBTs and Comparison of Two Modelling Approaches
Authors: Montante Giuseppina , Pinelli Davide , Magelli Franco 
Published: July 2010

AbstractThe features of solids concentration distribution were investigated in two baffled vessels of different scale. The vessels were of high aspect ratio and were stirred with multiple PBTs. Both steady‐ and unsteady‐state experiments were performed. The experimental data were compared with the previsions of the one‐dimensional sedimentation‐dispersion model and of CFD tools. The former approach provides good estimates only of the average, steady‐state vertical profiles, while the latter describes the local variations much more accurately. Both approaches give fairly good estimates of the transient solids concentration distribution. The dynamic CFD simulations allowed us also to tune the value of the turbulent Schmidt number as a relevant parameter. Finally, both simulation approaches have confirmed that the particle settling velocity in a stirred liquid is a correct parameter to be used instead of the terminal settling velocity.
Experimental Analysis of Hydrodynamics Induced by a Moritz HAS Impeller in Laminar and Turbulent Regimes
Authors: Escudié Renaud , Liné Alain , Kiener Pierre 
Published: July 2010

AbstractThe hydrodynamics induced by a Moritz HAS impeller are investigated using the PIV technique. The purpose of this study is to extend the knowledge of this kind of impeller, well known in turbulent flow, to the transition regime and laminar flow. Measurements of instantaneous velocity fields are synchronized with the position of the blade of the impeller. The periodic motion induced by the impeller blade rotation is measured by this conditional averaging. A triple decomposition is used to analyze the levels of turbulent kinetic energy and periodic kinetic energy induced by the impeller. In a turbulent regime, the impeller induces axial flow: the magnitude of periodic fluctuation is low compared to the turbulent one. In a laminar regime, the impeller induces a tangential‐radial discharge flow, and periodic velocity fluctuations are limited to the vicinity of the impeller.