bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coupled optimization and evaluation of phase equilibria and thermodynamic properties of the benzene‐cyclohexane system
Authors: Sangster J. , Talley P. K. , Bale C. W. , Pelton A. D. 
Published: March 2009

AbstractAn extensive review of reported vapour‐liquid equilibrium, solid‐liquid equilibrium, excess enthalpy, excess heat capacity and other phase equilibrium and thermodynamic data for the system benzene‐cyclohexane is presented. Selected phase equilibrium and thermodynamic data have been simultaneously optimized and fitted to a single polynomial series expression in composition and temperature for the excess Gibbs energy of the liquid. This expression has been used to evaluate all the diverse types of data known for this system. This single expression gives a self‐consistent description of all known data in the very wide temperature interval 232–500 K.
Axial dispersion models for displacement washing of packed beds of wood pulp fibres
Authors: Poirier N. A. , Douglas W. J. M. , Crotogino R. H. 
Published: March 2009

AbstractAxial dispersion models were developed for displacement washing of black liquor from packed beds of wood pulp fibres using pure wash water. For high initial bed liquor concentrations, the simple axially dispersed plug flow model was satisfactory for describing the experimental displacement washing breakthrough curves. For low initial bed liquor concentrations, the model was modified by the addition of a source term to account for the release of adsorbed and absorbed solutes which are transferred from the fibres to the wash fluid, and which become significant at low concentrations. Equilibrium between the fibres and the surrounding liquor was assumed. The highest Peclet numbers corresponding to the highest displacement washing efficiencies were obtained at high bed heights and low bed consistencies, for any superficial velocity.
Modeling of naphtha pyrolysis in swaged coils
Authors: Parameswaran Ayalur K. , Sharma Vimal K. , Kunzru D. 
Published: March 2009

AbstractPyrolysis of naphtha in uniform diameter and swaged reactors has been modeled. Pyrolysis and coking models available for naphtha cracking were used to calculate the reactor profiles of pressure, process gas temperature, tube metal temperature, conversion and the product yields. For the swaged coil, not only was the inlet pressure and maximum tube wall temperature in the clean condition lower than for a uniform diameter reactor, but the increase in the inlet pressure and maximum tube wall temperature due to coke deposition was also less. Swaging the reactor can result in a significant increase in the run length between decokings.
The use of the simplex method to characterize dry cellulose acetate membranes for gas separations
Authors: Tremblay A.‐Y. , Fouda A. , Lui A. , Matsuura T. , Sourirajan S. 
Published: March 2009

AbstractThe normal and log‐normal distributions are used to describe the pore size distribution of dry asymmetric cellulose acetate membranes for CO2/CH4 separations. Various optimization techniques are implemented to determine the distribution parameters R and σ as well as the constants A1, and A2, related to pore structure and surface transport. respectively. By using the Simplex method, a unique solution for the characterization parameters is easily obtained irrespective of the starting search point. The permeation data of helium was used to characterize the membranes and determine the flow parameters which can be used to predict the performance of those membranes in separating CO2/CH4 mixtures.
Mass transfer in tube bundles with liquid fluidized particles
Authors: Nieva Isabel A. , Böhm Ursula 
Published: March 2009

AbstractExperimental studies were conducted of overall and local tube‐to‐liquid mass transfer for bundles of horizontal tubes in staggered and in‐line arrays in a liquid fluidized bed. The mass transfer coefficients are compared with those obtained using a fixed packing and those obtained without particles at the shell‐side of the bundle.
Experimental study of dispersion in a consolidated sandstone
Authors: Kinzel Douglas L. , Hill Gordon A. 
Published: March 2009

AbstractDispersion experiments were conducted on a Berea sandstone core having a permeability of 0.28 (μm)2, using chloride ion as the water soluble tracer to provide quantitative information useful to the prediction of the motion of reservoir fluids in enhanced oil recovery. Both single phase (water only) and two phase (water plus oil) experiments were completed under identical operating conditions in order to observe flow differences. The theory of Ebach and White (1958) was used to determine the dispersion coefficients. It has been found that over a wide range of fluid velocities, low concentrations of oil have no effect on the dispersion of chloride ions in the water phase but high concentrations of oil (S0 ˜ 0.55) resulted in a dispersion coefficient 2.2 times higher than for chloride ions in water alone.This work indicates that the presence of an immiscible phase has a pronounced affect on the dispersion coefficient in porous media and must be accounted for in quantitative modeling of reservoir flows.
Mass transfer and selectivity of ozone reactions
Authors: Mehta Y. M. , George C. E. , Kuo C. H. 
Published: March 2009

AbstractThe present research concerns the behavior of mass transport in absorption of ozone accompanied by decomposition and ozonation reactions in aqueous solutions. On the basis of the film theory, a mathematical model has been formulated for the transport process taking into account molecular diffusion and the simultaneous decomposition and ozonation reactions of different orders. Analytical approximate and finite difference methods have been employed to predict concentration profiles, enhancement factor and selectivity of the chemical mass transfer in gas‐liquid systems.The rate of mass transfer is enhanced by the chemical reactions as well as the availability of liquid reactant in the aqueous phase. When the ozonation reaction is much faster than the decomposition reaction, a large fraction of the absorbed ozone is utilized effectively in reacting with the liquid constituent and a high selectivity of the gas‐liquid reactions can be obtained. Calculated results indicate that removal of certain organic pollutants by the oxidation process may be effective only in acidic or neutral solutions where a high mass transfer rate and selectivity is achieved.
Expansion behaviour of confined fluidized beds of fine particles
Authors: Donsì G. , Ferrari G. , Formisani B. 
Published: March 2009

AbstractThe expansion behaviour of fluidized beds of fine particles confined within packings of coarse spheres has been studied experimentally. An expansion law of the Richardson‐Zaki type has been demonstrated to be valid in a wide range of voidages for fine particles belonging to A as well as to B group of Geldart's classification. Parameters of the proposed correlation have been evaluated and their dependence on fines properties discussed.
The reaction network for the oxidation of propylene over a bismuth molybdate catalyst
Authors: Tan H. S. , Downie J. , Bacon D. W. 
Published: March 2009

AbstractAn initial‐rate study was conducted to determine the kinetics of the oxidation of acrolein over a bismuth molybdate catalyst. The results were combined with results from a previous initial‐rate study of propylene oxidation on the same catalyst to develop a quantitative description of the reaction network for propylene oxidation.The redox steady‐state model with half‐order in oxygen which provided the best fit to the propylene oxidation data also provided the best fit to the acrolein oxidation data. The disappearance of propylene occurs through parallel reactions to acrolein, carbon oxides, and acetaldehyde, with subsequent oxidation of the acrolein to carbon oxides.
Pyrolysis of grain screenings in a batch reactor
Authors: Utioh Alphonsus C. , Bakhshi Narendra N. , Macdonald Douglas G. 
Published: March 2009

AbstractA preliminary study of the pyrolysis of grain screenings (wheat) has been carried out using a batch pyrolysis unit operating at atmospheric pressure. Grain screenings are the materials removed mechanically from grains (wheat, rapeseed, barley, etc.) by cleaning or separating equipment in grain elevators. Reaction conditions were varied to determine the effect of these changes on the final product (tar, gas, and char). The reaction variables manipulated included temperature (600–800°C), nitrogen carrier gas velocity, and potassium carbonate catalyst. It was found that the yields of ethylene were higher than those of ethane. These hydrocarbons were accompanied by smaller but significant yields of hydrogen and C4 to C6 hydrocarbons. The grain screenings impregnated with 15 wt% potassium carbonate catalyst gave higher synthesis gas yields with a H2/CO mole ratio up to 4.1. With the experimental set up used in the present study, the mass balances achieved were low and ranged between 65 and 77% of the weight of the grain screenings used.
Gibbs energy of mixing from empirical models
Authors: Peng Ding‐Yu 
Published: March 2009

AbstractThe Gibbs energy of mixing loci for selected nonideal binary systems at low pressures have been calculated using the gamma‐phi approach. It is shown that, in order to yield correct results which are consistent with both the Gibbs energies for the pure components and the theory of representing the coexisting phases by a simultaneous tangent line, the fugacities of the pure components must be properly defined. Each of the Gibbs energy of mixing loci so calculated consists of two distinct curves for the homogeneous vapor and liquid phases and the simultaneous tangent line(s) for the heterogeneous region(s).
Mathematical model for gas flow through a packed bed in the presence of sources and sinks
Authors: Osinski E. J. , Barr P. V. , Brimacombe J. K. 
Published: March 2009

AbstractFlow within a packed bed is normally calculated by attempting to simultaneously satisfy the continuity and Ergun equations. However, the presence of gas sources/sinks within the bed escalates the complexity of the problem, particularly when the flow is two‐dimensional and a solution to the full Ergun equation is required. In quest of an efficient and dependable algorithm for the calculation of gas flow, a critical review of existing solution methods was undertaken and a new method, ‘FLOW’, is now proposed. The technique retains the viscous and inertial pressure gradient terms of the Ergun equation, and both are treated as linear functions of the flow. Solutions are approached iteratively; using finite difference techniques, the continuity and linearized Ergun equations are solved for the pressure field; a new flow field is then calculated from which is derived an adjustment to the inertial resistance term of the Ergun equation. The sequence is repeated until satisfactory convergence is obtained. Relatively few iterations are normally required and, for the case of negligible inertial pressure drop, one calculation cycle is sufficient. A comparison of results obtained using the ‘FLOW’, modified ‘SIMPLE’ and vorticity procedures is presented. The proposed method allow flexibility in the specification of boundary conditions and can be applied to compressible or incompressible flow, as well as for the case of nonisothermal beds.
Experimental study of the elutriation of particles from rotary kilns
Authors: Tackie E. N. , Watkinson A. P. , Brimacombe J. K. 
Published: March 2009

AbstractThe elutriation rate of fine solids from a rotary cylinder was studied as a function of air flowrate, rotational speed, percentage of solids fill, wall roughness and fine solids fraction. Local fines concentrations measured in the gas phase showed that solids travelled predominantly in saltation within 2 cm of the bed surface. The elutriation rate was influenced by cylinder exit dam geometry, wall roughness and segregation patterns in the bed. Gas velocity showed a very strong effect, with elutriation rate varying with velocity to a power of 4.6. An entrainment mechanism has been formulated based primarily on the collision of saltating particles on the solids bed.
Assessment of control loop performance
Authors: Harris Thomas J. 
Published: March 2009

AbstractFor processes described by linear transfer functions with additive disturbances, the best possible control in the mean square sense is realized when a minimum variance controller is implemented. It is shown that an estimate of the best possible control can be obtained by fitting a univariate time series to process data collected under routine control. No ‘identifiabüity’ constraints need be imposed. The use of this technique is demonstrated with pilot plant and production data.
Flow characterization of a flotation column
Authors: Pal Rajinder , Masliyah Jacob 
Published: March 2009

AbstractThe flow characteristics of a froth flotation column have been experimentally studied using air and aqueous surfactant solutions without the presence of solids. The hold‐up behaviours of the bubbly and the froth zones of the column were linked together using the drift‐flux model. The ratio of the gas drift‐flux, jgf, to the bubble terminal velocity, V, for both the bubbly and the froth zones was found to be well correlated by the Richardson–Zaki equation:
Phase equilibrium in the system water‐hydrogen sulphide: Modelling the phase behavior with an equation of state
Authors: Carroll John J. , Mather Alan E. 
Published: March 2009

AbstractIn the light of the information presented by Carroll and Mather (1989), a new interpretation is presented for the often‐quoted, smoothed data of Selleck, Carmichael and Sage (1952) for the phase equilibrium in the system water‐hydrogen sulphide. The data of Carroll and Mather show that the liquid‐liquid‐vapour locus extends to higher temperatures than believed by Selleck et al. Experimental data from several sources are correlated using the Stryjek‐Vera (1986a) modification of the Peng‐Robinson (1976) equation of state. It is demonstrated that the fit of the raw data via the equation of state is as good as the smoothing of Selleck et al.
A numerical solution for the dispersion in laminar flow through a circular tube
Authors: Takahashi Teruo , Korenaga Takashi , Shen Fenghua 
Published: March 2009

AbstractA numerical solution based on the method proposed by Bailey and Gogarty was developed to describe the solute dispersion in laminar flow through a straight tube of circular cross section. Many studies have been carried out since Taylor (1953) first presented a partial differential equation to describe the problem. The advantages of the present numerical solution are that it involves less numerical computation than others and can give very accurate results. It is also convenient to use because of its simplicity. The results obtained by this solution are in excellent agreement with those of Yu's solution, which is considered to be the most satisfactory approximation among the previous studies. The numerical solution also agrees very well with the experimental results for a finite slug of dye solution dispersed into water in laminar tube flow. A method was developed to check the computing error by means of a mass balance on the solute.
Hydrodynamic and thermal modelling of a high temperature spouted bed reactor with a draft tube
Authors: Stocker Rudolf K. , Eng John H. , Behie Leo A. 
Published: March 2009

AbstractA new multi‐region, nonisothermal computer model of a spouted bed reactor with a draft tube has been developed. The model rigorously accounts for the mass, momentum, and energy interactions between the annulus and the spout both above and below the base of the draft tube. Additional reaction due to the residence time of the gases in the fountain region is also accounted for. Investigations involving the ultra‐rapid ultrapyrolysis of propane indicate that a spouted bed reactor with a draft tube is ideal for very fast reactions of this type as both high heating rates and short reactant gas residence times can be achieved within the reactor. Simulations indicate the reactor to be capable of heating the spout gases at maximum rates between 50 000 and 90 000 K/s. Gas residence times of 30 ms or less within the draft tube and 400 ms or less in the reactor were predicted by the model for conditions typical of those required for propane ultrapyrolysis.
Chemical enhancement in the determination of KLa by the sulfite oxidation method
Authors: Thibault Jules , Leduy Anh , Denis Alain 
Published: March 2009

AbstractResults obtained by Ogut and Hatch (1988) for oxygen transfer rate into mechanically agitated Newtonian fluids are examined. Results indicate that volumetric oxygen transfer coefficients measured by the sulfite oxidation method can be much higher than the oxygen transfer coefficients obtained by other methods if the concentration of cobalt, used to catalyse the reaction, is above a certain critical concentration.
On structural changes of lignite char during fluidised bed combustion
Authors: Haldar S. , Saha R. K. 
Published: March 2009

AbstractExperiments were conducted to study structural changes (diameter, specific surface area and density) and mode of combustion of lignite char in a fluidised bed combustion process. Analysis of data demonstrates the effect of attrition along with combustion. Internal burning at least to the extent to which burn off has been studied, does not play a significant role. Despite attrition effects, the change in diameter approximates that of an idealised shrinking sphere.
Performance of combined mesh packing and sieve tray in distillation
Authors: Chen G. X. , Afacan A. , Xu C. , Chuang K. T. 
Published: March 2009

AbstractThe hydraulic and mass transfer performance of a combined knitted mesh packing and sieve tray has been measured for the distillation of methanol‐water mixtures. It was found that by adding a shallow bed of packing, the Murphree tray efficiency increased by 40–50% over a wide range of concentrations and flow rates. This increase in tray efficiency can be attributed to a much smaller and more uniform bubble formation on the packed tray. Hydraulic measurements have shown that the packed trays have lower weeping and entrainment, as well as slightly higher froth heights and pressure drops.
Modelling a uranium ore bioleaching process
Authors: Chien Daniel C. H. , Douglas Peter L. , Herman Dennis H. , Marchbank Andrew 
Published: March 2009

AbstractA dynamic simulation model for the bioleaching of uranium ore in a stope leaching process has been developed. The model incorporates design and operating conditions, reaction kinetics enhanced by Thiobacillus ferrooxidans present in the leaching solution and transport properties.Model predictions agree well with experimental data with an average deviation of about ± 3%. The model is sensitive to small errors in the estimates of fragment size and ore grade. Because accurate estimates are difficult to obtain a parameter estimation approach was developed to update the value of fragment size and ore grade using on‐line plant information.
Reactive crystallization of calcium carbonate by gas‐liquid and liquid‐liquid reactions
Authors: Kotaki Yasushi , Tsuge Hideki 
Published: March 2009

AbstractCrystallization of calcium carbonate by gas‐liquid and liquid‐liquid reactions in a continuous MSMPR crystallizer was conducted over a wide range of suspension densities. The effects of operating factors and reaction mechanism on the cyrstallization kinetics were investigated.The crystallization kinetics for both reaction systems are correlated by the power law model and these correlations depend on the suspension density regions. The kinetic orders in the power law model are correlated with carbonate alkalinity irrespective of the reaction mechanism and the suspension density.
Implications of standard states and ideal solution in terms of Raoult's law
Authors: Peng Ding‐Yu 
Published: March 2009

AbstractTraditionally, Raoult's law has always been considered to describe the vapor‐liquid equilibrium of ideal solutions. This treatment not only is awkward but also is not in complete agreement with the definition of an ideal solution in the sense of the Lewis‐Randall rule.In this study, the characteristics of a model system of Raoult's law are analyzed. The analysis is based on the application of the Lewis‐Randall rule in which the actual states of the pure components are used as the standard states. It is shown that, in the region where vapor‐liquid equilibrium exists, neither the vapor nor the liquid is an ideal solution in the strict sense of the Lewis‐Randall rule.
A corresponding states treatment of saturated density, surface tension and capillary constant of cryogenic liquids and refrigerants
Authors: Srinivasan K. 
Published: March 2009

AbstractUsing a new set of energy (kT) and length (σ) parameters, a corresponding states treatment is applied to the calculation of some thermophysical properties in a generalised non‐dimensional form. The saturated density is well represented by the following equation:

for all the liquids studied here. The surface tension correlations are \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _r^* = 2.055\left({1.219 - T_r^*} \right)^{1.240} $\end{document} for cryogenic fluids and hydrocarbons and \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _r^* = 2.322\left({1.228 - T_r^* } \right)^{1.244}$\end{document} for refrigerants. An interpretation of the index in the density equation and the constants in the surface tension equations is given. Using these correlations, an equation is also proposed for the capillary constant.
Absorption of CO2 by aqueous diethanolamine (DEA) solutions in a high shear jet absorber
Authors: Chakma A. , Chornet E. , Overend R. P. , Dawson W. H. 
Published: March 2009

AbstractCO2 diluted with N2 was absorbed by aqueous DEA solutions in a high shear jet absorber consisting of a high pressure stainless steel vessel with a pressure nozzle at the top. The results show that equilibrium conditions can be rapidly reached under high shear conditions. CO2 removal expressed by moles of CO2 absorbed per mole of DEA increased with gas flow rate and decreased with liquid flow rate. The overall mass transfer capacity coefficient Kg a was found to increase with gas flow rate and solution concentration. Kg a went through a maximum with solution flow rate. Increasing the CO2 partial pressure was found to decrease Kg a.
Deactivation of ICI low temperature methanol catalyst in an industrial reactor
Authors: Islam K. A. , Earl W. B. 
Published: March 2009

AbstractThe deactivation behavior of one of the ICI low temperature methanol catalysts (ICI‐51‐Z) in a typical ICI multibed quench reactor has been studied in relation to methanol production with respect to time of operation, using some representative sets of plant data collected over two years time span. A pseudo‐homogeneous first order model of the methanol synthesis reactor was formulated for this purpose. The best set of catalyst deactivation parameters for different beds was found using a nonlinear parametric estimation technique. Catalyst in the entering bed was found to deactivate most with the time of operation, while subsequent beds deactivate progressively less quickly.