bluuebunny/crossref_metadata_2025_split huggingface dataset:
A continuous process for recovery of sulfur from natural gas containing low concentrations of hydrogen sulfide
Authors: Ghosh Tushar K. , Tollefson Eric L. 
Published: March 2009

AbstractA continuous catalytic process was developed to remove hydrogen sulfide from a natural gas stream using activated carbon as catalyst. The concentration range of hydrogen sulfide in the gas stream studied was 300–3000 ppmv (0.0126–0.126 moles/m3). Virtually 100 percent conversion of hydrogen sulfide was achieved by the combination of various parameters. The “field gas” employed in this study exhibited cracking of some heavier hydrocarbons and made the product sulfur slightly brown. These hydrocarbons should therefore be separated from the gas stream prior to the oxidation reaction. No carbon monoxide or carbon dioxide was produced during the oxidation of hydrogen sulfide.It is concluded that the process described herein has the potential for the removal of hydrogen sulfide as sulfur from a sour natural gas stream on a continuous basis and could therefore eliminate an environmental problem which now exists.
Prediction of the volume correction factor in gas–liquid systems
Authors: Guha D.K. , De P. 
Published: March 2009

AbstractAn expression for the 'volume correction factor', which accounts for the fraction of the liquid volume remaining attached to the nozzle after drop detachment, has been arrived at after making a pertinent force balance. This expression has been compared with expressions of other investigators in the field. The final correlation, based on the derived equation and experimental data covering a wide range of clear liquids and nozzle diameters, gives a value of 0.35 for the volume correction factor. It may be utilised for theoretical estimation of the drop volume.
Performance analysis of the ring furnace used for baking industrial carbon electrodes
Authors: Bui R. T. , Charette A. , Bourgeois T. , Dernedde E. 
Published: March 2009

AbstractA model is developed for the purpose of analyzing the performance of the ring furnace and the effect of various operational parameters on energy consumption, furnace behavior and product quality. The model combines an energy balance on the gaseous stream and a calculation of heat transfer inside the solids. The process is a semi‐continuous counterflow heat exchange, further complicated by other phenomena such as air infiltration into the flue, evolution of volatile matter, and heat losses. Several simulation runs are made which succeed in reproducing the various real‐life operating conditions, and predicting furnace behavior and efficiency for other conditions. The model proves to be a useful tool for the analysis of this important and costly equipment of the aluminium industry.
Transfert de matière liquide‐paroi et hydrodynamique de l'écoulement de couette‐taylor‐poiseuille biphasique
Authors: Legrand J. , Coeuret F. 
Published: March 2009

AbstractLe travail étudie expérimentalement le transfert de matière liquide‐paroi en présence d'un écoulement biphasique (solide‐liquide ou liquide‐liquide) dans un espace annulaire cylindrique avec rotation du cylindre intérieur et débit axial (écoulement de Couette‐Taylor‐Poiseuille). L'existence d'une phase dispersée maintient le régime d'écoulement‐constitué par le mouvement axial de cellules tourbillonnaires toroïdalesNdashsur un domaine hydrodynamique beaucoup plus étendu que dans le cas d'un écoulement monophasique. Les coefficients de transfert de matière augmentent de manière très sensible avec la présence d'une phase disperséde; cette augmentation est měme importante (de 60 à 100 %) dans le cas d'une émulsion.
Sensitivities in representing the phase behaviour of gas‐bitumen systems
Authors: Fu C.‐T. , Puttagunta V. R. , Hsi C. 
Published: March 2009

AbstractTwo well‐known cubic equations of state (PR and MSRK) were used to test the sensitivity in predicting the vapour‐liquid equilibrium (VLE) properties of gas‐bitumen mixtures using a set of published critical parameters for bitumen. The predicted results were inconsistent and indicated the need to develop critical parameters that reflect compositional variations in bitumens. Sensitivity studies were also conducted using critical parameters developed by correlations based on compositional analyses of bitumens. It was shown that with these new parameters, both equations of state predict reliable VLE compositions and liquid phase densities. It was also found that there are minima in the critical temperature and critical pressure for the Athabasca bitumen, indicating that the new parameters are closer to the “true” values.
Gas hold‐up in highly viscous pseudoplastic non‐newtonian solutions in three phase sparged reactors
Authors: Dharwadkar S. V. , Sawant S. B. , Joshi J. B. 
Published: March 2009

AbstractGas hold‐up structure was studied in a three phase sparged reactor of 200 mm diameter. Air and aqueous solutions of carboxymethyl cellulose were used as gas and liquid phases. Spherical glass beads formed the solid phase. The superficial gas velocity, rheological properties, particle size and solid loading were varied over a wide range and their effects on gas hold‐up structure were studied. A correlation for the estimation of the gas hold‐up as a function of superficial gas velocity, apparent liquid viscosity, particle settling velocity and solid loading was established.
Design and optimization of the gel solar pond
Authors: Wilkins E. , Lee T. K. 
Published: March 2009

AbstractThe gel pond concept is a unique modification of the conventional salt gradient solar pond. It replaces the salinity gradient zone by a transparent polymer gel and thereby eliminates all problems of instability associated with the former. A framework for the preliminary design of a gel pond to serve different purposes has been presented here.Heat extraction at constant pond storage zone temperatures of 40°–80°C at storage zone depths of 2–5 m has been considered and optimum pond dimensions have been predicted depending upon maximum and minimum heat load constraints. The computer simulations are carried out with the meteorological conditions for Albuquerque, New Mexico. For example, the simulations show that the gel pond can provide an average heat load of 107 W/m2, a typical domestic water heating requirement, at a constant pond temperature of 40°C with a storage zone depth of 4.0 m and gel thickness of 0.6 m. For the case of power generation, the pond can provide a minimum of 32 W/m2 at a constant pond temperature of 80°C with a storage zone depth of 4 m and gel thickness of 0.6 m. These factors combined with the easy operation and maintenance of the gel pond seem to make it a better alternative compared with the conventional salt gradient pond.
Solution of stiff convection‐diffusion differential equations using marquardt's method
Authors: Hayes R. E. , Tanguy P. A. 
Published: March 2009

AbstractA modified Marquardt method is successfully used to solve a stiff non‐linear convection‐diffusion problem with chemical reaction. An efficient solution strategy is proposed and comparisons are made with classical iterative solution methods based on loading. The performance of the algorithm is illustrated with an implicit finite difference method.
Mathematical model for process design and simulation of dephlegmators (partial condensers) for binary mixtures
Authors: Cave Sergio Di , Mazzarotta Barbara , Sebastiani Enzo 
Published: March 2009

AbstractA mathematical model of dephlegmation processes (i.e. of partial condensation with countercurrent flow of rising vapour and falling condensate) has been proposed and the results of the simulation have been compared with those of five series of experimental runs carried out with two different binary systems. The agreement between calculated and measured values of the variables (compositions, temperatures, heat transfer surface) has been found satisfactory. Moreover, the extent of the rectification obtained from the experimental runs is generally small and appears to be slightly sensitive to both the temperature and the flow rate of the coolant.
Measurement of large gas‐liquid interfacial areas by the light transmission method
Authors: Urua Ini J. , Del Cerro M. C. G. 
Published: March 2009

AbstractTheoretical formulations previously put forward to account for the effect of multiple scattering in the measurement of gas‐liquid interfacial areas, at high AL values, are critically assessed. It is shown that inconsistencies arising from these can be satisfactorily resolved on the basis of the theory of Al Taweel et al. (1984) and experimental data available in the literature for the evaluation of the different parameters associated with the theory. An equation is proposed for the calculation of large gas‐liquid interfacial areas for AL ≤ 280 and excellent agreement between predicted and experimental values is demonstrated.
Viscosity of compressed cold lake bitumen
Authors: Mehrotra Anil K. , Svrcek William Y. 
Published: March 2009

AbstractViscosity data over a temperature range of 37‐115°C and a pressure range of 0‐10 MPa gauge are presented for a Cold Lake bitumen sample. These data show that the compression of Cold Lake bitumen results in a significant increase in its viscosity. Results are compared with those from a similar study on an Athabasca bitumen sample. Also presented are two correlations for the effects of pressure and temperature on the viscosity of Cold Lake bitumen.
Role of capillary and viscous forces in mobilization of residual oil
Authors: Patel K. , Greaves M. 
Published: March 2009

AbstractExperimental results are reported for a series of microemulsion displacement tests carried out in a consolidated core of medium permeability (1.75 μm2). The interfacial tension and viscosity were varied from 0.02 to 32.0 mN/m and 2.0 to 26.0 mN · s/m2, respectively. The amount of oil unrecovered is correlated as a function of capillary number, Nc. Results are compared with those obtained by other workers who used porous media of low permeability and the relative importance of capillary and viscous forces at various stages of oil mobilization is discussed.
Enzymatic hydrolysis of a Populus deltoides Substrate from a Thermo‐mechanical Treatment of Medium Consistency Slurries
Authors: ČApek‐MÉNard E. , Preiss B. , Bouchard J. , Chornet E. , Jaulin L. , Overend R. P. 
Published: March 2009

AbstractGround Populus deltoides was pretreated using a thermo‐mechanical process in which shear forces are applied by rapid passage of concentrated slurries (10‐14%) through homogenizing valves. The process permits accurate control of operational parameters to induce varying degrees of ultrastructure modification in the substrate. The poplar was pretreated at two levels of severity in the absence of mineral acid and a process time of the order of 2 minutes. The high severity pretreated substrate was more susceptible than commercial α‐cellulose to enzymatic saccharification by T. reesei cellulase supplemented with cellobiase (glucose yields of 103 ± 6% and 76.2 ± 1.8% respectively in 48 hours).
The kinetic rate of combustion of electrode carbon in the temperature range of 1000‐1200 k
Authors: Halder P. K. , Basu P. 
Published: March 2009

AbstractKinetic rates of combustion of electrode carbon particles were measured in a temperature range of 1000‐1200 K. Spherical carbon particles of size 7‐9 mm are burnt in hot streams of nitrogen‐oxygen mixtures. The velocity and the temperature of the mixture were varied. To compensate for the mass transfer resistance to the flow of oxygen to the carbon surface a mass transfer experiment was carried out in the same apparatus.By using mass transfer coefficients from the above experiment kinetic rates are analysed statistically to give the following Arrhenius type correlation of the kinetic rate:

where n is in the range of 0.3 to 0.5.
Effects of oil phase viscosity on interfacial tension behaviour of oil/alkaline systems as measured by the spinning drop tensiometer
Authors: Neale Graham H. , Khulbe Kailash C. , Hornof Vladimir 
Published: March 2009

AbstractThis note examines the effects of oil phase viscosity on the interfacial tension of reacting systems (acidic crude oils in contact with alkaline solutions) as measured by the Spinning Drop Tensiometer. Surfactants are produced by chemical reactions at the interface, thereby causing the shape of the oil droplet in the tensiometer to change continuously. The rates of droplet elongation/contraction are necessarily influenced by the oil phase viscosity, thereby affecting directly the measured interfacial tension. The principal conclusion of this work is that although oil phase viscosity exerts a significant effect on the dynamic interfacial tension after attainment of the minimum value, it makes for only a small absolute change in the magnitude of the minimum interfacial tension itself.
Periodic operation of transport reactors for catalytic reactions
Authors: Sivakumar S. , Chidambaram M. , Shankar H. S. 
Published: March 2009

AbstractBased on plug flow of gas and catalyst particles and concentration dependent deactivation kinetics, the performance of transport reactors under a periodic (rectangular pulse) inlet concentration is analysed for improvement in conversion and extent of catalyst decay. The effects of reaction and deactivation orders, reaction and deactivation constant groups, and γ (cycle split) on the performance of the reactors are evaluated theoretically. For reaction orders greater than one, periodic operation improves conversion. Resonance behaviour is observed for certain combinations of parameters. For identical operating conditions vertical upflow, downflow and horizontal flow reactors are compared. Conversion in upflow reactors is higher than that in either horizontal flow or downflow reactors. However, catalyst decay is the least in downflow reactors.
Two classes of anionic surfactants and their significance in hot water processing of oil sands
Authors: Schramm Laurier L. , Smith Russell G. 
Published: March 2009

AbstractIn hot water flotation of bitumen from Athabasca oil sands, two types of primary oil recovery response to sodium hydroxide addition are identified. Natural carboxylate surfactants can promote bitumen separation and flotation under certain process conditions, while a second, more polar, class of natural anionic surfactants can promote separation and flotation under different process conditions. As a result, some oil sands exhibit two recovery peaks as a function of sodium hydroxide addition. The phenomena are explained in terms of different sodium hydroxide additions required to reach critical surfactant concentrations specific to each surfactant class. The concept provides a means for interpreting a wide range of processibility phenomena.
The statistical properties and utility of rational functions models
Authors: Ratkowsky D. A. 
Published: March 2009

AbstractRational functions, also called “inverse polynomials”, have been used as approximations to a wide range of mathematical functions and integrals in computer applications. A fairly general rational functions model with a single regressor variable and three to five parameters, capable of fitting a wide variety of ascending and descending curves, including sigmoidal curves and curves with maxima and minima, was considered here. Good fits to a wide range of data were obtained, and generally, the model exhibited “close‐to‐linear” estimation behavior. Such behavior guarantees convergence to the least squares estimates using the Gauss‐Newton algorithm in only a few iterations starting with a set of “reasonable” initial estimates.
Characteristics of jet fuels produced from hydrogenated shale oils
Authors: Mukherjee N. L. 
Published: March 2009

AbstractShale oils from the United States (Geokinetics, Occidental, Paraho and Tosco II) were hydrotreated, fractionated into jet fuel cuts (boiling range 121–300°C), then characterized to evaluate their suitability as jet fuels. Nitrogen content was considerably higher, though the amount of hydrogen was relatively lower, than in typical petroleum jet fuels. Sulfur content was significantly below the acceptable limit. Trace metal contents in shale oil jet fuels were below the maximum levels for those in petroleum jet fuels. Vanadium, copper, lead and alkali metals were not present. Physical properties, except freezing points, were comparable to those of standard jet fuels.
Traitement par une méthode d'éléments finis de modèles de colonnes de rectification discontinue à garnissage
Authors: Aly S. , Pibouleau L. , Domenech S. 
Published: March 2009

AbstractLes auteurs présenters des modèles mathématiques traduisant différentes représentations du fonctionnement d'une colonne de rectification discontinue à garnissage. On traite dans une première partie le fonctionnement en régime stationnaire à reflux total en considérant un écoulement piston du flux liquide et de la vapeur auxquels on superpose le phénomène de dispersion axiale et radiale. Les équations sont résolues par une méthode d'éléments finis de type Galerkine ainsi que par une méthode de différences finies. L'exploitation du modèle de fonctionnement en régime stationnaire avec dispersion axiale et radiale a permis de constater que cette dernière peut ětre négligée dans la plupart des cas. Par contre, l'étude du fonctionnement dynamique a montré que l'introduction du phénomène de dispersion axiale était toujours nécessaire pour représenter la réalité physique de façon satisfaisante.
Surface phenomena and hydrodynamic effects on the deposition of pseudomonas fluorescens
Authors: Pinheiro M. M. , Melo L. F. , Bott T. R. , Pinheiro J. D. , Leitão L. 
Published: March 2009

AbstractBiofilm adhesion to metals (copper, aluminium and brass) was studied at two different velocities and pH values of 7 and 9. Both bacteria and metals showed negative surface charges at those values of pH, which tends to slow down adhesion. Film densities increased with the fluid velocity and were also affected by the pH and by the growth rate of the bacteria. Long duration tests based on heat transfer measurements were run at five different fluid velocities and at pH = 7, showing in general an asymptotic behaviour and a control of deposition by adhesion and growth phenomena.
The influence of fluid elasticity on wall effects for creeping sphere motion in cylindrical tubes
Authors: Chhabra R. P. , Uhlherr P. H. T. 
Published: March 2009

AbstractExperimental results are presented of wall effect for the slow motion of spheres in elastic, constant‐viscosity liquids. The results are correlated in terms of diameter ratio for d/D < 0.3, and Weissenberg number We < 5. Weissenberg number is defined as We = 2θVm/d, with θ the Maxwellian relaxation time (θ = N1/2τγ).The wall effect is found to be adequately described by Newtonian expressions for small Weissenberg number, We < 0.01. For larger values of the Weissenberg number, We > 0.2, virtually no wall effect is discernible; the small effect observed is correlated by the wall factor expressionThe wall effect observed is ascribed to the influence of fluid elasticity alone, since all the fluids used were elastic to a greater or lesser extent, but showed no shear thinning.
Hydrodynamics and liquid phase axial mixing in orifice pipe reactor
Authors: Lali A. M. , Khare A. S. , Joshi J. B. , Eapen A. C. , Rao S. M. , Yelgaonkar V. N. , Ajmera R. L. 
Published: March 2009

AbstractTwo phase flow in a horizontal pipe, with orifice plates placed at regular intervals as obstructions, was studied for the effect of phase velocities on flow patterns, fractional phase hold‐ups, pressure drop and liquid phase axial dispersion. Radioactive technetium‐99m (as an aqueous solution of sodium pertechnatate) was used as tracer. A pulse injection technique with two point measurements was employed. Three different orifice diameters were used (8 mm, 16 mm, and 20 mm) in a pipe diameter of 32 mm. The orifice spacing was 500 mm in all cases. Superficial gas (air) velocity was varied over a range from 0.02 m/s to 1.0 m/s and superficial liquid (water) velocity from 0.03 m/s to 0.85 m/s.Different flow patterns under different flow conditions were identified and a generalised flow map is presented. Variations in hold‐ups and pressure drop with flow patterns have been explained. Rational correlations have been developed for fractional phase hold‐ups and pressure drop. A preliminary comparison of two phase gas‐liquid flow in a horizontal pipe with orifice obstructions (to be called orifice pipe reactor), as a gas‐liquid contacting device, is made with a conventional bubble column reactor. Recommendations have been made for future work.
An accelerated successive substitution method for single stage flash calculations
Authors: Gupta Anup K. , Bishnoi P. R. , Kalogerakis N. 
Published: March 2009

AbstractAn acceleration technique, based on the Dominant Eigenvalue Method of Orbach and Crowe (1971), is proposed to accelerate a successive substitution method in which liquid and vapor compositions are used as the iteration variables. The performance of this scheme is compared with the accelerated successive substitution method of Mehra et al. (1983) and the General Dominant Eigenvalue Method (GDEM) of Crowe and Nishio (1975) as implemented by Michelsen (1982, 1987) which iterate upon the equilibrium ratios. The proposed acceleration scheme exhibits a less oscillatory behavior during convergence, and requires less storage than the accelerated methods using the K‐factors as the iteration variables. However, the number of thermodynamic evaluations is comparable with that of Mehra et al. (1983) and is more than that of Michelsen (1982, 1987).
Conjugate heat transfer in turbulent falling liquid films
Authors: Gorla R. S. R. , Maloney T. 
Published: March 2009

AbstractHeat transfer characteristics for a falling turbulent liquid film flow over a fin are analyzed using the conjugate convection‐conduction theory. Numerical results are obtained from a simultaneous solution of the energy equations of the fluid and the fin. Results are presented for the fin temperature distribution, dimensionless heat transfer coefficients, local heat fluxes, and fin efficiencies.
A gas‐solid reaction model — Variable temperature, pressure and structural parameters
Authors: Hastaoglu M. A. , Hassam M. S. 
Published: March 2009

AbstractDiffusion and reactions in a porous pellet are treated as transient, nonisothermal, nonisobaric processes. Continuity and energy balance equations are solved simultaneously for temperature and concentration profiles in the pellet. Conductive, convective as well as radiative heat transfer are included. The ‘dusty gas’ flux model is used to describe the transport of diffusing gases. Viscous, bulk and concentration gradient terms have been included. Structural changes with reaction are accounted by considering the effect of changing grain radius on porosity and pore diameter.The model predictions match conversion trends for carbon gasification over a temperature range of 800 to 1100°C investigated experimentally.
Self‐Tuning control of fischer‐tropsch synthesis in a tube‐wall reactor
Authors: Rohani Sohrab , Quail D. W. , Bakhshi N. N. 
Published: March 2009

AbstractThis paper describes the implementation of a self‐tuning controller (STC) on a bench‐scale tube‐wall reactor for the Fischer‐Tropsch synthesis using a plasma‐sprayed iron catalyst. The concentration of the hydrocarbons in the C10 range in the reactor effluent was controlled by manipulating the H2/CO ratio of the inlet synthesis gas. The output of the self‐tuner was cascaded to two PI‐controllers which maintained a constant total inlet gas flow rate as well as ensuring the desired H2/CO ratio. The concentration measurement was performed by an on‐line gas chromatograph with an analysis time of approximately 30 s. The performance of the STC in set‐point tracking, rejection of randomly occurring deterministic disturbances, and estimation and adaptation to the unknown process dead time was investigated. The STC was able to reduce the variance of the process output and of the manipulated variable when compared to the variances obtained with a PI‐controller.