bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Correlations for Mass Transfer Coefficient in Ultrafiltration Systems
Authors: De S. , Bhattacharjee S. , Bhattacharya P. K. 
Published: August 2010

AbstractCorrelations for the determination of the mass transfer coefficient in ultrafiltration systems are developed. This was done by the inclusion of a new dimensionless number relevant for ultrafiltrative systems; namely, the Peclet number based on the test cell experimental flux. The incorporation of this group altered the estimate of the mass transfer coefficient significantly. The development of the present correlations was done by regression analysis over the experimental data obtained in our laboratory as well as those reported in the literature for both laminar and turbulent regimes. Experimental estimates of mass transfer coefficients in a number of UF devices using various feed solutions were used to develop the correlations. Detailed statistical analyses were carried out to test the adequacy of the developed correlations and the model parameters. Correlations are also developed for an industrial effluent (black liquor) for different flow configurations and regimes. Values of mass transfer coefficients obtained from the developed correlations were also compared with those obtained from the standard correlations and velocity variation technique. Developed correlations should be useful for ultrafiltration system design.
Composite Membrane Systems for High‐Temperature Chemical Catalytic Processing
Authors: Gobina E. , Hou K. 
Published: August 2010

AbstractA study has been carried out to assess the relative performance characteristics of dense and porous composite membranes for high‐temperature alkane dehydrogenation. Rigorous two‐dimensional mathematical models have been developed and applied to describe the various processes of transport and chemical reaction taking place in these complex novel reactor systems. The orthogonal collocation technique has been used to simulate the industrially important dehydrogenation of ethylbenzene to styrene as the model reaction. The results have clearly demonstrated superior performance of dense composite membranes below a thickness of 50 μm. However, above this thickness porous composite systems are preferable in terms of conversion enhancement, but all the systems depict identical performance at a separation layer thickness of 150 μm. The performance of the systems is also studied by obtaining the conversion level as a function of the contact time parameter using various feed compositions. These findings have demonstrated that exclusive hydrogen permeability is important, provided the separation layer thickness is not too great.
Diffusional Analysis during Air Drying of a Starch Food System
Authors: Mcminn W. A. M. , Macgee T. R. A. 
Published: August 2010

AbstractStarch, as a major component of several food products of plant origin, was used as a simulant for investigation of the basic physical and engineering properties of particulate and porous foods. An experimental tunnel dryer was used to investigate the drying‐rate and temperature profiles developed within potato starch gel cylinders during convective drying. The experimental diffusional data were characterised using Fick's second law and an empirical model was developed to predict the effective moisture diffusivity as a function of air temperature, air velocity and sample radius. The experimental and predicted results were in good agreement. The temperature distribution developed within the sample were measured and presented as a function of both drying time and dimensionless distance.
Limitations on the Applications of Advanced Process Control in Mineral Processing Operations
Authors: Tade M. O. , To L. C. , Ray M. S. 
Published: August 2010

AbstractThe development of advanced control theory has received considerable attention in academia over the past two decades, and extensive applications can be found in the literature for systems other than industrial process control, for example, vehicle control, robot control, electrical machines and systems control. Applications in the process industry are gradually increasing, see for example [I]. However, relatively few industrial examples of advanced control applications have been reported for the mineral processing industry. A review of the current status of modern control as applied to mineral processing operations (MPO) is given in this paper. The limitations of these techniques which have caused reluctance in their acceptance by the industry are discussed. Two case studies of our experiences in applying modern control techniques in alumina refineries are presented. Insights are also provided on how to bridge the gap between academia and industrial practice of process control in this area.
Technical and Economic Considerations of Solid Oxide Fuel Cell Systems
Authors: McCahey S , McMullan J. T. , Williams B. C. 
Published: August 2010

AbstractThe ECLIPSE process simulator has successfully evaluated the technical and economic performance of a number of systems based on a natural gas fed Solid Oxide Fuel Cell (SOFC). These systems differ in their approach to reforming of the natural gas feedstock and in their use of anode gas recycle. The most efficient system is the direct internal reforming SOFC with an efficiency of 48.0% giving C02emissions of 420 g/kWh. The indirect internal reforming and the external reforming SOFC have efficiencies about 3.5 to 4 percentage points lower. The total energy efficiencies vary between 87.2% and 91.0% and if the useful, high grade heat could be converted into electricity via steam turbines then the electrical efficiency increases by about 10 % points. The effect of anode gas recycle is to improve the electrical efficiency by on average 7.5 % points and to reduce C02emissions by 15%.Compared to conventional power generation technologies, the efficiency of, and C02emissions from, a direct internal reforming SOFC are vastly superior to the small scale gas turbine and gas engine systems and slightly better than the large scale gas turbine combined cycle systems. However, from the point of view of cost of electricity, for the SOFC to compete with the small scale systems the SOFC capital cost must be reduced to less than either 500/kWe with a lifetime of greater than 15 years or 600/kWe with a lifetime of greater than 20 years. For SOFC systems to compete with large scale gas turbine combined cycle systems they must be used in a combined heat and power configuration with a similar capital cost as above. Current estimates for SOFC costs are around 1000/kWe with an uncertain lifetime. Therefore, at this stage, the economic viability of SOFC power generation systems depends on cost reduction and lifetime enhancement, probably via materials development and operating temperature reduction.
The Development and Characterisation of Sorbents from Irish Sphagnum Moss Peat
Authors: Whitten L. J. , Allen S. J. 
Published: August 2010

AbstractA range of carbon chars was produced from sphagnum moss peat by heating in a furnace with a reduced oxygen atmosphere. A series of heating times and temperatures were selected for the preparation of the chars. Comparative porosity and surface area studies, based on nitrogen sorption isotherms and mercury porosimetry data, were carried out to characterise the chars. Further characterisation studies were condućted by electron microscopy techniques. Optimum charring conditions, yielding maximum surface area for N2 adsorption, were observed at a charring temperature of 800°C and charring time 30 minutes. Using the optimum charring conditions, a further series of chars was produced. Prior to charring the raw peat was chemically pre‐treated with a range of metal salt solutions of varying percentage concentration. The resulting chars were characterised as above. The adsorptive capacity of these chars for N2 was investigated on the Sorptomatic 1900 (Fisons Instruments). The adsorption isotherms were compared to the standard isotherms of Langmuir. Adsorbate uptake was seen to vary with surface area availability, pore volume, pore type and the nature of the adsorbate.
A Revised Analysis of the Effect of Surfactants on Two‐Phase Phenomena in Horizontal Air‐Water Pipe Flow
Authors: Spedding P. L. , Hand N. P. 
Published: August 2010

AbstractFlow regimes, hold‐up and pressure loss measurements in two‐phase air‐water co‐current horizontal flow have shown that the effect of surfactant was to: a. suppress the formation of ripples or gravity waves; b. progressively extend the range of the smooth stratified pattern at the expense of the ripple flow regime, as the gas rate was increased; c. increase the liquid hold‐up above that for water alone over the wavy regimes from the top end of the smooth stratified pattern to the onset of film‐plus‐droplet flow, and there was a corresponding reduction in pressure loss. The mechanism responsible for the suppression of waves resulted in a reduction in the ability of the gas to scour out the liquid. The fundamental cause for these effects was linked to local variations in surface tension as the surface film on the liquid was alternatively expanded and compressed by the ripples. Additional effects of surfactant at other flow conditions were that: d. drag reductions occurred in the slug and plug regimes with the surfactant affecting the liquid slug nose regions; e. drag reduction also occurred in the annular regime at high gas and liquid flow rates, caused by the damping of waves at the base of the annular film. These results help explain a number of apparent anomalies presented in the literature.
Recent Developments in Photocatalysis
Authors: Howe R. F. 
Published: August 2010

AbstractThis article reviews some recent developments in the area of photocatalysis. These include the development of methods for preparing nanocrystalline (Q‐sized) TiO2, the doping and promotion of titania to improve its photoreactivity, recent studies of reaction mechanisms, the introduction of other oxide photocatalysts, and recent advances in the design of reactors for photocatalysis. It is concluded that practical implementation of photocatalysis, particularly in environmental applications, is now close to reality.
Modeling of Fluidized Bed Reactors for the Polymerization Reaction of Ethylene and Propylene
Authors: Abasaeed A. E. , Al‐Zahrani S. M. 
Published: August 2010

AbstractPolyethylene and polypropylene are used worldwide due to their versatile physical and chemical properties. A simplified dynamic model is developed to describe the polymerization reactions in a fluidized bed reactor. The effect of two important operating parameters, i.e. catalyst injection rate and superficial velocity, on the performance of the unit are investigated. Qualitatively as well as quantitatively different bifurcation diagrams are obtained for each case. However, in both cases, operation of the reactor is confined to the stable low monomer conversion region due to polymer softening temperature limitation.
Removal of Lead(II) by Mordenites
Authors: Dai S. , Kato Y. , Guang D. , Amal R. 
Published: August 2010

AbstractBatch studies were conducted to investigate the removal of Pb2+ using mordenite. Effects of lead concentration, solution pH, particle size and dosage of mordenite on the removal kinetics and the removal capacity of lead were investigated. It was found that the main removal mechanism was ion exchange, with Na, Ca, and K as major exchange cations. The exchange kinetics and the exchange capacity of lead with the cations in mordenite increased as the lead concentration increased. The solution pH affected the exchange rate but not the lead exchange capacity. The reaction rate at pH 5 was faster than that at pH 3. As the particle size of mordenite decreased, the reaction rate increased. The exchange rate of lead also increased as the mordenite dosage increased. A significant removal of lead by mordenite was observed. For a lead concentration of 3 ppm, 99% of the lead was removed, and for a high lead concentration (200ppm), 70% lead removal can still be achieved. It can be concluded that mordenite has a great potential to remove lead from wastewaters.
Partial Oxidation of Propylene Over Hydrophobic Catalysts in a Slurry Reactor
Authors: Liang W. , Chuang K. T. , Zhou B. 
Published: August 2010

AbstractPropylene partial oxidation over hydrophobic catalysts was studied in a slurry reactor. Due to the hydrophobicity of the catalyst, a direct reaction mechanism between the gas phase reactants and the catalyst was proposed for the reaction. The experimental results and the predictions based on this model are consistent, indicating that the proposed mechanism is reasonable for propylene oxidation over the hydrophobic catalyst. Also, due to the hydrophobicity and the low density of the catalyst, it is observed that there is non‐uniform catalyst particle distribution in the reactor. The effect of the catalyst particle non‐uniformity on the reaction is discussed and predictions are made based on the model. The effect of different operating conditions for the slurry reactor on propylene conversion, selectivity to CO2, and acrylic acid yield have been studied. A comparison between results obtained using the hydrophobic and hydrophilic catalysts shows the advantage of using the hydrophobic rather than hydrophilic catalysts for propylene partial oxidation in the slurry reactor, which is attributable to the direct reaction mechanism over the hydrophobic catalysts.
The Production and Characterisation of Activated Carbons: A Review
Authors: Allen S. J. , Whitten L. , Mckay G. 
Published: August 2010

AbstractThe uses of active carbons and carbon chars for liquid and gas phase applications has been presented. Their application for decolourising, water treatment, solvent recovery, military uses, nuclear industry, air purification, domestic uses, precious metal recovery and catalysis, have been outlined. A detailed review of the production and manufacture of activated carbons from a wide range of carbonaceous sources is given. Methods of activation are discussed based on a range of chemicals and how these chemicals influence surface activity, pore size and pore distribution. The techniques for characterising activated carbons are reviewed in detail and include porosimetry, sorptometry, topography, pore size distribution, isotherms and surface area measurements. The specific results of some active carbons derived from lignocellulosic materials (peat and lignite) are also presented.
In‐situ Regeneration of Phenol‐Saturated Activated Carbon Using Ethanol
Authors: Matheickal J. T. , Yu Q. , Linden J. 
Published: August 2010

AbstractIn‐situ regeneration of spent activated carbon can be a more cost effective alternative than the thermal regeneration method. This paper studies the suitability of ethanol for the regeneration of a granular activated carbon (Filtrasorb‐400), that was saturated with phenol from wastewater. Ethanol is less hazardous, completely miscible with water and offers convenient solvent recovery. The adsorption capacity of fresh activated carbon for phenol was found to be 208 mg g−1. The recovery of phenol adsorption capacity of the carbon, operated cyclically using a sequence of phenol adsorption, desorption with ethanol, and rinsing with water, was determined in both batch and fixed‐bed processes. The kinetics of the regeneration process were also studied. In the fixed‐bed process, the regeneration efficiency by using ethanol was 98% after the first regeneration cycle and 94% after the third regeneration cycle. The corresponding values for batch operations were 89% and 85%, respectively. The kinetics of regeneration in batch processes were fast, and 90% of the total regeneration was complete within 30 minutes. The results from this study indicate that ethanol could be used to regenerate granular activated carbon in‐situ with only marginal loss of adsorption capacity.
Dissolution of Phosphate Rock by Mixtures of Sulfuric and Phosphoric Acid
Authors: Jamialahmadi M. , Emam S. H. , Müller‐Steinhagen H. 
Published: August 2010

AbstractThe dihydrate process for the production of phosphoric acid is increasingly important as the basis for phosphate fertilizer plants. The process involves dissolution of phosphate rock in an aqueous mixture of phosphoric and sulfuric acid and subsequent crystallization of calcium sulfate dihydrate from the product phosphoric acid solution. In this study the mechanisms of dissolution of phosphate rock are studied using reagent grade and plant acids. The effects of various operating parameters such as temperature, particle size and excess sulfuric acid concentration on the rate of dissolution of rock are investigated. The results show that the dissolution of the rock occurs in two stages of different rates. Initially, the dissolution process is fast and is controlled by chemical reaction between rock and acid. In the second stage, when the particles are coated by calcium sulfate dihydrate the dissolution process is slow and controlled by mass transfer of acid through the coating layer.
Vertical Two Phase Flow
Authors: Woods G. S. , Spedding P. L. , Watterson J. K. , Raghunathan R. S. 
Published: August 2010

AbstractData are presented on flow regimes, holdup and pressure drop for vertical co‐current two phase flow in a 0.026 m i.d. pipe. A universal flow regime map was not possible but flow regime transitional equations were developed for the slug to churn, churn to semi‐annular, semi‐annular to annular and annular to annular ripple boundaries. Holdup was shown to be predicted by the Nicklin [15] relation for intermittent regimes and the Spedding‐Chen [16] relation for annular flows. Pressure drop in the slug regime was shown to be subjected to an uplifting effect due to liquid being held in the wake of the rising gas bubble. Pressure loss prediction was possible for bubble, slug and annular regimes only.
Reaction Hysteresis: A New Cause of Output Multiplicity in Reactive Distillation
Authors: Sneesby M. G. , Tadé M. O. , Smith T. N. 
Published: August 2010

AbstractJacobsen and Skogestad (1991) described two causes of multiple steady states in binary distillation via an analysis of the fundamental equations of the equilibrium stage model for distillation processes. Later, Bekiaris and Morari (1993) described multiple steady states in azeotropic distillation using a geometric analysis based on the conditions of perfect fractionation (infinite number of stages and infinite reflux ratio). Commercial process simulators (Pro/IITM and Speed UpTM) were used to investigate multiple steady states in reactive distillation via the construction of bifurcation diagrams (the locus of solutions obtained by varying a single continuation parameter). These results indicate that the mechanisms described by Jacobsen and Skogestad (1991) and Bekiaris and Morari (1993) are each pertinent to reactive distillation processes. However, some examples of multiple steady states cannot be adequately explained with the available explanations and a fourth cause of output multiplicity, applicable only to hybrid reactive distillation, was proposed. Supplementary simulation studies indicate that the proposed explanation is sound.
The Use of Metallocene Catalysed Polyethylene as a Blend Material in Blown Film Extrusion
Authors: Beagan C. M. , Mcnally G. M. , Murphy W. R. 
Published: August 2010

AbstractMetallocene catalysed polyethylenes are the latest addition to the polyethylene family and are reported to have superior mechanical properties over conventional polyethylenes. This paper sought to investigate the effect of blending these materials with conventional low density polyethylene for use in thin films, suitable as packaging materials and produced by the blown film process. Two grades of Metallocene catalysed polyethylene were used in the study. Films containing increasing percentages of these resins were produced at various processing conditions and their mechanical properties considered. These films were then characterised using Differential Scanning Calorimetry and Dynamic Mechanical Thermal Analysis techniques. This work showed that increasing the percentage of metallocene catalysed polyethylene in a low‐density polyethylene film improved the mechanical properties of the resultant film.
The Relevance of Predictive Techniques to Industrial Combustion and Heat Transfer Problems
Authors: Mullinger P. J. 
Published: August 2010

AbstractControl of fire is the very foundation of our industrialised society, and whilst most processes will continue to rely on fossil fuel combustion for the foreseeable future, a wide range of organic wastes is being used, and more can potentially be used, to supplement fossil fuels. Landfilling waste liquids such as cleaning solvent, used lubricating oil and hydrocarbon wastes from various manufacturing processes potentially pollute the soil, water courses and the air (by evaporation). By comparison the use of waste liquids as fuel can result in significant environmental benefits and provide cost savings for the plant. Burning these liquids eliminates these sources of pollution and recovers heat for the process ‐ hence saving fossil fuels, such as coal, natural gas and fuel oil, for the future. An effective and low cost technique is to burn wastes directly in suitable process plants. To utilise these resources effectively however requires a good understanding of the combustion and heat transfer processes in the plant to ensure production capacity and emissions are not adversely affected. Successful application of wastes as supplementary fuel requires careful analysis of the effect on plant operation and the environmental impact well ahead of permit applications, or a trial burn. The complexity of the combustion and heat transfer processes make such an analysis technically difficult, but no less essential.
Large‐Scale Structure in Turbulent Diffusion Flames ‐ Evidence, Implications, Origins
Authors: Mungal M. G. 
Published: August 2010

AbstractThis work reviews some evidence for the existence of large‐scale structures in turbulent diffusion flames, at low and high Reynolds numbers, for free jets and jets in crossflow over a range of buoyancy conditions. The striking differences between the velocity field and the scalar field will be highlighted and implications for mixing and reaction are explored. The origins of these differences are discussed by analogy to simple large‐scale wave motions in the velocity field leading to complex mixing patterns in the scalar field.
Modeling of Infra‐Particle C‐CO2 Reaction: An Application of the Random Pore Model
Authors: Liu G.S. , Tate A.G. , Rezaei H.R. , Beath A.C. , Wall T.F. 
Published: August 2010

AbstractThe Random Pore Model developed by Bhatia et al. was applied to intra‐particle gasification reactivity of carbon with carbon dioxide in present contribution. Instead of the conventional n‐th order equation, the Langmuir‐Hinshelwood equation, which treats reaction to be an adsorption and desorption two‐step reaction, was employed as an expression for the carbon and carbon dioxide surface reaction in the model. A balance between gas diffusion and consumption for each position in the particle was established as derived in the Thiele analysis. Numerical calculations were carried out to solve the integrated equations. The results show that a big difference of reaction rate is exhibited between using the n‐th order rate expression and the Langmuir‐Hinshelwood (L‐H) equation. The results also show the distributions of CO2 partial pressure, surface area, reaction rate and carbon conversion within the particle during the gasification. The overall conversions at different structure parameters, which are correspondent to initial porosity of 0.05, 0.2 and 0.4, are also presented in the paper. A small deviation of the effectiveness factors obtained between using the Langmuir‐Hinshelwood and the n‐th order equation is indicated with the carbon burn‐off between 0–85%.