bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multistage multicomponent separation calculations using thermodynamic properties evaluated by the srk/pr equation of state
Authors: Shah M. K. , Bishnoi P. R. 
Published: March 2009

AbstractA computational procedure using thermodynamic properties evaluated by the Soave‐Redlich‐Kwong' (SRK) equation of state or the Peng‐Robinson (PR) equation of state is developed for multistage multicomponent separation processes. The procedure makes use of the Ishii‐Otto convergence scheme with the proposed modifications for application with the equation of state. A new technique is developed to improve an initial estimation of temperature profile in a column. The computational procedure is tested on CDC CYBER 172 computer for a wide range of problems including lean oil absorbers, reboiled absorbers and fractionators and a debutaniser operating in a natural gas processing plant in Alberta. The computational results are compared with those obtained using the Chao‐Seader model for generating the required thermodynamic properties. It is concluded that the present computational procedure can be used more reliably over a wider range of processing conditions such as those involved in the cryogenic separation of natural gases and in the separation of heavy hydrocarbon mixtures.
Application des chaînes de markov discrétisées à la simulation des réacteurs chimiques
Authors: Masson H. A. , Tolley M. D. 
Published: March 2009

AbstractGibilaro et al(1) ont montré l'intérět du formalisme des chaǐnes de Markov(2), discrétisées dans le temps, pour la simulation de distribution de temps de séjour d'éléments fluides dans des mélangeurs imparfaits.La présente note reprend brièvement les points essentiels de leur travail. On décrit ensuite quelques extensions de la théorie originale. On montre comment introduire les temps morts, une alimentation continue en traceur, et comment généraliser au cas de systèmes sièges de réactions chimiques.Trois exemples simple illustrent la mise en oeuvre de l'algorithme et permettent de juger de la précision obtenue, par comparison avec les solutions analytiques (méthodes) de Merson et de Runge‐Kutta).
A kinetic model for continuous‐flow stirred biological reactors
Authors: Lo S. N. , Marchildon L. , Lakshmanan R. , Garceau J. J. 
Published: March 2009

AbstractA kinetic model is proposed to describe the mechanisms of substrate removal in continuous‐flow, stirred bioteactors for bacterial autocatalytic reactions. A lumped parameter, defined as the average number of contacts between microorganisms and limiting substrate per unit time per unit of biomass, is used to study the overall effect of mixing on reactor performance. Under all the conditions studied, the overall effect is such that the larger the value of the parameter the better the reactor performance. The influence of formation and decomposition of cell‐substrate intermediate on substrate removal is also presented.
The influence of precipitated asphaltenes on sedimentation of particles in coal liquids
Authors: Verhoff F. H. , Lui S. S. , Henry J. D. 
Published: March 2009

AbstractAntisolvent addition to coal liquids causes the precipitation of asphaltenes on mineral particles and increases their sedimentation rate. This paper develops a mathematical model of the sedimentation rate of a single particle or agglomerate of particles. It was found that if the difference in density between the solid and the precipitate is more than twice the difference in density between the precipite and the liquid, the sedimentation rate would decrease initially upon precipitation. A simple experiment was performed to confirm the prediction. Further it was found that the agglomeration of particles had a stronger effect upon the sedimentation than the changes in particle size.
Height and structure of the fountain region above spouted beds
Authors: Grace J. R. , Mathur K. B. 
Published: March 2009

AbstractThe height and structure of the fountain which forms in the freeboard region above the annular surface of a spouted bed is predicted based on equations of motion for particles entrained in the spout. Predicted fountain heights are in good agreement with a wide range of experimental values covering polystyrene particles, wheat, millet, glass beads and ammonium nitrate spouted in columns of diameter up to 0.292 m. A simplified procedure in which drag is ignored gives good results also under most circumstances of practical importance. The theoretical niodel proposed can be used to predict the voidage profile in the fountain core and the holdup of particles ill the freeboard, both of which may be useful in estimating the performance of spouted bed reactors.
Correlating parameters for axial dispersion in liquid fluidized systems
Authors: Krishnaswamy P. R. , Ganapathy R. , Shemilt L. W. 
Published: March 2009

AbstractThe dispersion coefficient, the time delay and the time constant, as parameters associated with models of liquid phase axial dispersion in fluidized systems, have been correlated using available literature data for fluidization involving a wide range of fluid and particle properties. The results permit prediction of these parameters from only a knowledge of the bed voidage. A comparison with Chung and Wen's1 correlation demonstrates the superiority of the present correlation.
Conversions and temperature rises in a laminar flow reactor for the hydration of acetic anhydride
Authors: Golding J. A. , Dussault R. 
Published: March 2009

AbstractThe hydration of acetic anhydride in concentrated solutions has been studied in a vertical laminar flow reactor. The effects of flowrate, reactant concentration and reaction conditions on conversions and temperature rises were studied. An effect of the initial acetic acid concentration was observed. Thus at low acid concentrations there was good agreement between experimental and prediction values. However, at high acid concentrations, above 1.2 mole/l acid, the reaction was apparently inhibited and experimental results were lower than predicted. Radial teniperatnre profiles were measured and found to be relatively flat despite the low Reynolds numbers existing iu the reactor.
Calculations of gas phase diffusion and reaction in heterogeneous catalysts the importance of viscous flow
Authors: Haynes Henry W. 
Published: March 2009

AbstractThe problem of multicomponent gas phase diffusion fora single overall reaction in porous catalysts is analyzed using the dusty‐gas theory. Recent authors have shown that neglecting internal pressure gradients results in modeling inconsistencies and errors in computation in small pore catalysts. However, calculations based upon kinetic theory estimates of the transport coefficients reveal that the viscous flow contribution to the component i molar flux can be neglected with excellent justification. The resulting equations are internally consistent and greatly simplified. For illustrative purposes the multicomponent example of P. Schneider7 is reformulated to take into account nonuniform pressure (but negligible viscous flux), and as a consequence the inconsistency noted in the original reference is removed. Two methods for computing the effectiveness factor are discussed.
Comparison of catalytic cracking on lax and lay catalysts
Authors: Yeh Jer‐Jeng , Wojciechowski B. W. 
Published: March 2009

AbstractA comparison of the cracking activity and gasoline selectivity on LaX and LaY has shown that LaY is a superior catalyst both in terms of activity and in terms of gasoline selectivity at high conversions.There is reason to believe that the LaX catalyst used in this work was partly diffusion limited within the crystallite and that the activity and selectivity of X catalysts can be improved by producing X sieves in microcrystalline form.
Vapor‐liquid equilibrium behavior of the ethane—n‐butane—n‐hexane system
Authors: Dingrani J. G. , Thodos George 
Published: March 2009

AbstractA high pressure visual cell was designed and constructed for the study of vapor‐liquid equilibria of rnulticomponmt systems at elevated temperatures and pressures. One of the unique features of this vapor‐liquid equilibrium cell facility resides in the ability to measule pressures using a transducer connectcd directly to the equilibrium chamber of this cell. In addition, the design of this cell, incorporated the capability to permit the withdrawal of vapor and liquid microsamples from the respective phases in equilibrium. The composition of these microsamples was established with a gas chromatographic facility provided with a thermal conductivity detector. The overall performance of this vapor‐liquid equilibriiini facility was tested on the system ethane‐n‐butane for which reliable vapor‐liquid equilibrium data are already available in the literature.Five different charges of the ethane‐n‐butane‐n‐hexane system were investigated with this facility for temperatures ranging from 48.3 up to 143.5°C and pressures up to 7619 kPa (75.19 atm). For these conditions, K‐values were established from the experimental measurements on this ternary system. K‐values calculated using the BWR‐method for conditions corresponding to the experimental measurements produced K‐constants that were in good agreement with the measured values. For these calculations, the original BWR‐equation, constants and mixing rules were employed.
Decompression wave velocities in natural gases in pipe lines
Authors: Groves T. K. , Bishnoi P. R. , Wallbridge J. M. E. 
Published: March 2009

AbstractThe events following rupture of a pipeline containing gas at high pressure are very similar to those following rupture of the diaphragm in a simple shock tube. A description of the decompression wave resulting from such a rupture, and its rate of propagation in natural gases is the primary purpose of this paper. A computer program is written to calculate decompression wave velocities. The required thermodynamic properties are calculated using the Soave‐Redlich‐Kwong (SRK) equation of state and the results of computed wave velocities are presented and compared to values observed in the decompression zone of a shock tube.
Comparison of several turbulence models for predicting flow patterns within confined jets
Authors: Tennankore K. N. , Steward F. R. 
Published: March 2009

AbstractNumerical solutions of the differential equations governing isothermal and nonisothermal confined jets have been obtained for three different models of the turbulence correlation terms. The models used were1) mixing length model2) k‐l model3) k‐e modelA comparison of the predictions with experimental data taken in a confined jet system indicates that in the absence of a measured distribution of the kinetic energy of turbulence at the entrance section the mixing length model provided the best results for the isothermal case. For the nonisothermal jets, however, it was found that the k‐e model gives better prediction than the other two models in spite of the lack of measured distributions for the kinetic energy of turbulence at the entrance.
The coalescence of n‐Hexane droplets in aqueous electrolyte solutions
Authors: Sagert Norman H. , Quinn Michael J. 
Published: March 2009

AbstractCoalescence times, measured by high speed cinematography, are reported for n‐hexane droplets formed on adjacent nozzles in pure water and in dilute aqueous solutions of the electrolytes KCl, KBr, KI, NaCl, and Na2SO4. Coalescence times in pure water were 17 + 11 ms, in satisfactory agreement with recent theories of Ivanov and of Reed, Riolo and Hartland. Coalescence times increased on addition of electrolytes, except for KI. Limiting values of coalescence times in electrolyte solutions could be accounted for by the theories of Marrucci. Thus the Marrucci parameter crk2/λ may be taken as a guide to droplet coalescence in solutions of solutes such as electrolytes which only change interfacial tensions slightly. The coalescence times are larger than for air‐electrolyte solutions, largely because of the lower Hamaker‐London attraction with the present system.
Absorption of sulfur dioxide into limestone slurry in a stirred tank reactor
Authors: Uchida S. , Moriguchi H. , Maejima H. , Koide K. , Kageyama S. 
Published: March 2009

AbstractAn experimental study on the absorption of low concentration sulfur dioxide into limestone slurries in a stirred tank reactor has been performed. The absorption rates under various experimental conditions were measured and the absorption processes have been discussed. The analysis of the experimental data shows that the limestone dissolution process seems to play a very important role in the absorption.
Separation by thermodialysis of acetic acid aqueous solutions
Authors: Bellucci F. , Bobik M. , Drioli E. , Gaeta F.S. , Mita D.G. , Orlando G. 
Published: March 2009

AbstractThe effect of thermodialysis has been investigated in non‐ideal liquid mixtures, employing coarse, unselective porous partitions.For the case investigated — aqueous solutions of acetic acid — the temperature differences applied across the partition induced remarkable separations of the components. This effect may be applicable to the purification of industrial wastes. Furthermore, the investigation of thermodialysis in non‐ideal solutions has provided valuable data, aiding to our understanding of the physical basis of the phenomenon.
Poisoning and regeneration of claus alumina catalysts
Authors: George Zacheria M. 
Published: March 2009

AbstractSamples of poisoned alumina catalysts obtained from Claus sulfur recovery plants in Alberta have been regenerated. Poisoned catalysts had SO4=, NO3−, sulfur and carbon deposits, discoloration, and low surface areas. Whereas the Claus catalytic activity of the poisoned catalysts varied widely, regeneration uniformly enhanced the catalytic activity to the same level as fresh alumina. The activity comparisons were made under conditions similar to those of a third Claus converter of low partial pressures of H2S and SO2 and high partial pressure of H2O, where maximum catalytic activity is required to promote Claus reaction.
Gas‐solid reactions I: A grain‐cell model for complex reactions
Authors: Fahim M. A. , Wakao N. , Ford J. D. 
Published: March 2009

AbstractA mathematical model has been developed to describe the progress of a consecutive reaction taking place in a porous spherical pellet composed of two solids. Two basic parameters are derived: a Thiele type modulus (H), and a kinetic‐structural parameter (γ). The system of partial differential equations representing the model has been solved numerically, to obtain conversion‐time relations as a function of the physical and kinetic parameters of the system. Highest conversions are obtained at low values of both γ and H.
Gas‐solid reactions II: Reduction of cobalt sulfide in the presence of calcium oxide
Authors: Fahim M. A. , Ford J. D. 
Published: March 2009

AbstractThe results of an experimental program to test the applicability of the grain‐cell model to complex gas‐solid reactions are presented. The hydrogen reduction of solid cobalt sulfide (CO9/8S) in the presence of calcium oxide was chosen for study. Powders of both solids were mixed in a molar ratio of 3.0 (CaO:Co9/8S), compressed into pellet form, then reduced by hydrogen in the temperature range 600‐800°C. The experimental results at different operating conditions were compared with the grain‐cell model, using the Thiele type modulus (H) as an adjustable parameter. In the presence of excess calcium oxide, the structural‐kinetic parameter (γ) was essentially zero, and (H) was found to be the effective parameter, controlling reduction rates. Good agreement between experimental results and model was obtained.
The discrete residence time distribution of a distillation colum operated with microprocessor controlled periodic cycling
Authors: Furzer I. A. 
Published: March 2009

AbstractThe fluid flow in a distillation column was studied by measurements of the discrete residence time distribution. The column, 100 mm in diameter was fitted with 5 sieve plates of 14.8% free area with a 6.1 mm hole diameter on a 635 mm plate spacing. The periodic control was obtained using a JOLT microprocessor system. An analysis of the discrete residence time distribution yielded the parameters in the (2S) model that describes the fluid flow. Modifications to the column internals are required to alter these parameters, if the maximum separation improvements are to be obtained.
Separation of organic mixtures by sequential gas‐liquid chromatography
Authors: Barker P. E. , Liodakis S. E. , Howari M. I. 
Published: March 2009

AbstractA new sequential continuous chromatographic refiner (SCCR‐2) for high temperature production scale G.L.C. (gas‐liquid chromatographic) separations is described. In this equipment the counter‐current movement between the gas and liquid phase is simulated by sequencing a system of inlet and outlet port functions around twelve static 2.54 cm internal diameter and 61 cm long stainless steel columns. The versatility of the equipment has been demonstrated by the separation of equivolume mixtures of the halocarbons arklone P/genklene P, methylchloroacetate/ethyl lactate and ethyl caprate/ethyl laurate at temperatures of 60°, 105° and 160°C respectively. Throughputs between 21–75 cm3h−1 have been explored with product purities in excess of 99.8% achieved under certain process conditions.
Mixing of large particles in two‐dimensional gas fluidized beds
Authors: Fan L. T. , Chang Y. 
Published: March 2009

AbstractThe fluidization and solids mixing characteristics of very large particles were investigated in a two‐dimensional gas fluidized bed. Bubble or slug induced drift and gross solids circulation appeared to be the predominant solids mixing mechanisms in this large particle bed. The contribution from wake mixing appeared to be negligible and radial mixing was more rapid than axial mixing. Apparently, segregation in the axial direction resulted from preferential transportation of the lighter particles upwards with rising bubbles and from interparticle competition to fill the voidage created by the rising bubbles. No appreciable segregation occurred in the radial direction. A nonstationary random walk model has been developed to characterize mixing and segregation of fluidized large particles.
Integral conversion of SO2: Hysteresis and rate discontinuities
Authors: Kovenklioglu S. , Delancey G. B. 
Published: March 2009

AbstractThe oxidation of SO2 was carried out over an American Cyanamid V2O5 catalyst in an insulated integral reactor without significant interparticle resistances under the following conditions: 10 percent SO2‐air feed, feed temperatures in the range of 430°C to 590°C, 108 kPa pressure, and entrance temperatures of the gases in the annular heat exchanger from 400°C to 450°C, with one set of conversions being obtained without annular air flow. Gas analysis was accomplished by the oxidation of SO2 to SO3 with potassium permanganate. The method was fully tested before adoption. Final conversions in the range of 5 to 60 percent were observed. A hysteresis loop was found in the plane of outlet conversion versus the average feed temperature. The multiplicity is possibly stable but probably decays with the time constants in the order of days which is evident from the transient data that were obtained. A one dimensional model was able to correlate the conversion data through the Arrhenius rate parameters in the Boreskov‐Sokolova(8) rate expression which changed from A = 1.92 × 107 m3/(s·kg) and E = 151 MJ/kmol to A = 0.344 m3/(s·kg) and E = 33.5 MJ/kmol at a calculated temperature at the surface of the catalyst of 517°C. Similar behavior has been observed in other studies concerned with basic kinetic studies over catalyst pellets. The analogy between the behavior of the catalyst pellets and the behavior of the integral reactor can thus be fully drawn with respect to hysteresis and rate discontinuities.
Behaviour of V2O5 — catalyzed CO oxidation in the presence of inert, diluent gases
Authors: Silva A. E. M. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractA study was conducted on the oxidation of CO over an industrial potassium‐promoted V2O5 catalyst in order to study the influence of He, Ar, Kr, SF6 and C4F8 diluents on the reaction rate. A differential flow reactor was used between 400° and 440°C with partial pressures of CO2, O2 and diluents varied from approximately 7 to 150 kPa. All the diluents inhibited the reaction rate to varying degrees. Experiments were also performed in which one diluent gas was displaced by another in the reaction mixture. These experiments indicated that the diluents could be arranged in the following increasing order of sorptive interaction with the catalyst:He or Ar < Kr < SF6 or C4F8It was concluded that conventional site‐blockage was unable to explain the influence of the diluents. An adsorption interaction between the diluent and the surface complex of the rate limiting step was postulated to explain the inhibition of diluents in CO oxidation and the enhancement of diluents in SO2 oxidation on the same catalyst.
Ion exchange with irreversible reaction in deep fluidized beds
Authors: Koloini T. , ŽUmer M. 
Published: March 2009

AbstractThe exchange of CI− ion between dilute aqueous solutions of hydrochloric acid and the ion exchange resin IRA‐425 in fluidized beds was studied in a laboratory size column. Analysis of the experimental data showed that axial mixing of particles in deep beds was incomplete and also that packed and fluidized bed break‐through curves were similar. A model is proposed describing the bed as a series of mixing stages for solids with axially dispersed flow of liquid. Data are presented in support of such a concept.An empirical method is proposed for prediction of the break‐through curves at various operating conditions, requiring only a very limited amount of experimentation.
A fluidized bed catalytic cracking regenerator model
Authors: Effects Grid , Errazu A. F. , Lasa H. I. De , Sarti F. 
Published: March 2009

AbstractA grid model including thermal effects is proposed. The aim is the simulation of a fluidized catalytic cracking regenerator similar to the industrial unit of Destileria La Plata, YPF, Argentina.It is demonstrated that a simple C.S.T.R. model without bypass of gas feed entering the bed provides a good approach for representing the fluidized bed including the grid region.In addition, by means of the C.S.T.R. model, it is shown that there exist two characteristic operating regions: a zone where (Coo – Co) depends on the initial coke concentration and a zone where (Coo – Cc) is controlled by oxygen supply.
Thermodynamic properties of the system toluene — 1, 1, 1‐trichloroethane
Authors: Sundaram S. , Viswanath D. S. 
Published: March 2009

AbstractData on molar excess enthalpy on mixing at 298.15 K and 308.15 K, vapor‐liquid equilibrium, latent heats of vaporization at 91.444 kPa and vapor pressures for the system toluene – 1, 1, 1‐trichloroethane are presented. A simple adiabatic calorimeter designed for molar excess enthalpy measurements is described, tested and used.
Flow of slurries of coarse particles at high solids concentrations
Authors: Televantos Y. , Shook C. , Streat M. , Carleton A. 
Published: March 2009

AbstractUsing a lock hopper feeding system, gravel and coal shale slurries containing particles of median diameter approximately 4 mm were transported at high concentrations through a pipe of I.D. 7.87 cm at velocities below 3.5 m/s−1. In addition to the usual measurements of velocity, delivered concentration and hydraulic gradient, in‐situ concentrations and particle velocities were determined. With these measurements, a two‐layer model of stratified flow of the type proposed by Wilson was examined and found to give satisfactory predictions. Coefficients of wall friction were found to vary with velocity. Minimum values of these coefficients agreed with the results of direct shear tests. This variation could be attributed to stick‐slip processes at low velocities and a change in the nature of the interparticle stress at higher velocities.