bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquefaction of coal by SRC‐II process: Part I: A new kinetic model
Authors: Singh C. P. P. , Shah Y. T. , Carr N. L. , Prudich M. E. 
Published: March 2009

AbstractThe kinetic experiments were carried out in a continuous stirred tank reactor. Practically important ranges of SRC‐II reactor temperature (444–466°C), pressure (10.4–20.8 MPa), nominal slurry residence time (0.54–1.62 h), coal concentration in the feed slurry (25–35 wt%), and inorganic mineral matter concentration (4.75–13.43 wt%) were covered in a total of 43 experimental runs. In each of the experimental runs, the feed slurry was formulated by using vacuum tower bottoms from SRC‐II pilot plants using the same feed coal (Powhatan No. 5), to obtain feed compositions similar to those obtained in SRC‐II pilot‐plant recycle operation.The kinetic model considers the overall conversion to be achieved in two stages. The first stage is the instantaneous dissolution of coal and in the rate controlled second stage all the reactive organic components in the liquid phase are initially assumed to react, each yielding components lighter than itself. The distribution of products in each reaction stage is considered to be independent of the operating conditions. The best rate controlled (second stage) reaction scheme and values of the unknown parameters are obtained by minimizing the overall difference (i.e. for all the components over all the runs) between the measured and model predicted mass fractions of the various components in the reactor. This analysis identifies the reaction of solvent refined coal (pyridine soluble organic matter boiling above 482°C) to be the only significant reaction in the second stage and its rate is determined to be‐rSRC= 1.567 × 105exp (‐79.16/RT) ·p0.28·XASH, kg/L h. Overall error in this analysis yielding the reaction scheme, rSRCand values of product distribution coefficients for both the reaction stages is less than 8% absolute i.e. ±4%.
Liquefaction of coal by SRC‐II process: Part II: Simulation of an SRC‐II recycle system
Authors: Singh C. P. P. , Shah Y. T. , Carr N. L. 
Published: March 2009

AbstractThe kinetic model, described in the preceeding paper, is used in this work to obtain a general simulation of an SRC‐II recycle system. The present simulation considers the reactor to be isothermal and fully backmixed, reactions in the preheater to have insignificant influence on yields, and separation of the products into various fractions to be ideal. The concept of degrees of freedom is used to evaluate the number of independent variables for the complete (recycle) system. The model is validated against data from three different pilot plants on Powhatan, Kentucky, and Ireland Mine coals. The effects of various variables on yield behavior and distribution of solids throughout the system are illustrated. Operational difficulties encountered in increasing the recycle ratio of bottoms, containing solids, above 0.75 is explained.
A Chemical equilibrium model for interfacial activity of crude oil in aqueous alkaline solution: The effects of pH, alkali and salt
Authors: Chan Mankin , Yen Teh Fu 
Published: March 2009

AbstractA chemical equilibrium model is proposed to describe the effects of acid content, pH and sodium ion concentration on the interfacial activity of crude oil in aqueous alkaline solutions. The model is based on an equilibrium among the dissociation of acids in the crude, the dissociation of the sodium salt containing the active species and the dissociation of water. It is shown that once the pH of the interface reaches the pKa of the acids, the interfacial tension (IFT) drops steeply and that further addition of sodium ions increases the IFT by shifting the equilibrium to form undissociated soap.
Study of the catalytic effects of impregnated metals in the pyrolysis of peat
Authors: Roy Christian , Chornet Esteban 
Published: March 2009

AbstractA case study is presented and thoroughly discussed to show that through rigorous application of statistical criteria it is possible to: (a) unambiguously identity the effect of each catalyst tested upon overall yields; (b) determine the extent of the effect on individual product yields and (c) classify the catalysts on a performance basis.The study focuses on the pyrolysis of naturally occuring peat doped with small amounts of finely dispersed metals (K. Fe, Co and Ni) introduced by impregnation with their nitrate salts. The pyrolysis has been conducted on the air‐dry material under reduced pressure conditions at a heating rate of 10°C/min up to a temperature of 925°C.The statistical analysis resulted in rejection of the initial underlying hypothesis which considered that the metallic additives will exert an influence on the overall peat tar yield and composition. Presence of important amounts of silica (as ash) might have been responsible for the lack of catalytic effects observed. The work stresses the usefulness of repetitive runs to determine the inherent experimental error when conducting catalyst screening on real substrates.
Forced convection heat transfer in low prandtl number turbulent flows: Influence of axial conduction
Authors: Lee Shong‐Leih 
Published: March 2009

AbstractThe effect of axial conduction was investigated for turbulent heat transfer in a round pipe with uniform wall temperature. Exact solutions were obtained by using the method of separation of variables for the two cases with and without the axial conduction term.The solutions show that the effect of axial conduction is important at low Peclet numbers, say Pe < 100, but negligible in the thermally fully‐developed region. Also, the fully developed Nusselt numbers depend only on Reynolds number at low Peclet numbers and the interpolation formula is proposed:

which fits the calculated data well in the liquid metal range 0.001 < Pr < 0.022 for Pe < 100.
Entrainment by a concentric jet with particles in the secondary stream
Authors: Subramanian Viswanath , Ganesh Raman 
Published: March 2009

AbstractIn a two‐phase concentric jet the second phase, consisting of solids, influences the development of the jet and the effect of its presence needs to be assessed quantitatively. An experimental study of such a jet with particles in the secondary stream was therefore undertaken. It is seen that particles enhance the mixing.
Biotraitement aerobie, en reacteur completement agite, d'une eau residuaire de laiterie
Authors: Mayer R. C. , Rouleau D. , Royer G. 
Published: March 2009

AbstractSynthetic residual waters from dairies have been subjected to a laboratory‐scale treatment study.A thoroughly‐stirred continuous‐flow reactor involving no recirculation of the biomass has been used. The operation‐control two parameters have been (a) the mean residence time of the biomass and (b) the bioreactor temperature. The variables have been (i) the substrate removal expressed in terms of the chemical demand in oxygen (D.C.O.) and (ii) the biomass production expressed in terms of volatile suspended matters.The Monod model has adequately described the system behavior. The kinetic constants k, kd. Y, K, have been determined at 5, 15 and 25°C. The values of the substrate maximum rate of assimilation per biomass unit (k) and of the specific rate of the biomass deterioration rate (kd) have characterized the constants according to the Arrhenius Law in the range covered. The values of the half‐rate constant Ks have been high at the above‐mentioned three temperatures in comparison with the conventional values. The maximum coefficient of the yield (Y) has varied little with the temperature.
The flash pyrolysis of aspen‐poplar wood
Authors: Scott D. S. , Piskorz J. 
Published: March 2009

AbstractA continuous fluidized bed bench scale flash pyrolysis unit operating at atmospheric pressure and feed rates of about 15 g/h has been successfully designed and operated. A unique solids feeder capable of delivering constant low rates of biomass has also been developed. Extensive pyrolysis tests with hybrid aspen‐popular sawdust (105–250 μm) have been carried out to investigate the effects of temperature, particle size, pyrolysis atmosphere and wood pretreatment on yields of tar, organic liquids, gases and char. At optimum pyrolysis conditions high tar yields of up to 65% of the dry wood weight fed are possible at residence times of less than one second.
Recovery of residual bitumen from oil sand sludges
Authors: Denis C. E. St. , Kessick M. A. 
Published: March 2009

AbstractFactorial experiments were conducted to examine the effects of dilution, caustic addition and lime addition on the recovery of residual bitumen by flotation from oil sands tailings sludges. Dilution was found to be the most significant variable, and it was established that close to 100% recovery of the substantial quantity of residual bitumen could be achieved by flotation, after diluting 1 volume of sludge with 2 volumes of water. These results indicate that physical and chemical changes in the sludges may have occurred, during the storage period, to place the residual bitumen in a more accessible form. Atomic absorption analysis and infra‐red data on the sludge fractions indicate that the changes could have resulted from the interaction between calcium ion, present in the system in low concentrations, and surface active materials responsible for stabilizing the bitumen dispersed in the tailings.
Interfacial tension and phase behaviour characteristics of petroleum sulfonate/lignosulfonate mixtures
Authors: Son J. E. , Neale Graham H. , Hornof Vladimir 
Published: March 2009

AbstractThe interfacial tension and phase behaviour characteristics of mixed‐surfactant formulations containing petroleum sulfonate and lignosulfonate were investigated. Low interfacial tensions between oil and aqueous surfactant solutions were found to be closely related to the occurrence of a third phase, and hence to the general phase behaviour of the surfactant system. Ultralow interfacial tensions (>0.01 mN/m), which are well known between oil and pure petroleum sulfonate solutions, could still be achieved when using mixtures of petroleum sulfonate containing lignosulfonate. It is considered that these findings will have important economic implications in the recovery of oil from partially depleted oil fields.
The transfer of potassium chloride from n‐butanol to water
Authors: Sagert Norman H. , Lucy Charles A. 
Published: March 2009

AbstractA rotating diffusion cell was used to study the transfer of potassium chloride from water to n‐butanol to water under conditions of known interfacial area and hydrodynamics. Experiments were conducted at 25°C using 1.0, 2.0, 3.0 and 4.0 mol/dm3 KCl in the first aqueous phase. The system displayed no measurable interfacial resistance to mass transfer. This is understandable since the primary solvation spheres of both potassium and chloride ions are composed almost exclusively of water molecules, so no solvation needs to occur when the ions cross the interface. Since this result is consistent with earlier studies of the same system by a different technique, confidence in the validity of the rotating diffusion cell technique is increased.On a employé une cellule de diffusion rotative pour étudier le transfert de chlorure de potassium de l'eau au n‐butane, puis à l'eau, dans des conditions connues de surface interfaciale et d'hydrodynamique. On a fait ces expériences à 25°C, en employant 1.0, 2.0, 3.0 et 4.0 mol./dm3 de KCl dans la première phase aqueuse. Le système n'a présenté aucune résistance interfaciale mesurable au transfert de masse; ce fait est compréhensible, vu que les sphères de solvatation primaire des ions potassium et chlorure se composent presqu'exclusivement de molécules d'eau et qu'il n'est pas nécessaire qu'il se produise de solvatation lorsque les ions traversent l'interface. Etant donné que ce résultat concorde avec les résultats d'études antérieures du měme système par une méthode différente, il y a lieu d'avoir plus confiance en la validité de la méthode basée sur la cellule de diffusion rotative.
Stability of jets in liquid‐liquid systems
Authors: Kitamura Yoshiro , Mishima Hiroyuki , Takahashi Teruo 
Published: March 2009

AbstractExperiments were carried out to study the stability of jets in immiscible liquid systems under conditions where the jet velocity relative to continuous phase was zero. The laminar breakup lengths and the diameter of drops formed from laminar jets are in good agreement with the stability analysis for stationary column while breakup data for jets injected into quiescent liquids disagree with it. An approximate solution for theoretical drop size is presented. The experiment also showed that the hydrodynamic resistance of continuous phase increases the growth rate of disturbances but does not affect the wave length.
Operating characteristics and energy distribution in a nitrogen transferred arc plasma
Authors: Tsantrizos P. , Gauvin W. H. 
Published: March 2009

AbstractThe electrical characteristics of a nitrogen transferred arc plasma were measured in a closed chamber, which simulated a plasma furnace. The total arc voltage depended strongly on the arc length and much less on current and plasma gas volumetric flow rate, with a voltage gradient of about 12 V/cm. The various mechanisms accounting for the transfer of the energy in the arc to the system were identified and measured. The two major components of the energy distribution were by electron transfer to the anode (whether water‐cooled solid copper or molten metal) and by radiation from the plasma column.The significance of these measurements for the design and optimization of plasma furnaces is discussed.
Liquefaction of coal by SRC‐II process: Part IV: Steady‐state thermal behavior of the reactor
Authors: Singh Chandra P. P. , Carr Norman L. 
Published: March 2009

AbstractAn axial dispersion thermal model of an SRC‐II reactor is developed. The model is validated by simulation of steady‐state temperature profiles in the Fort Lewis (Tacoma, Washington) pilot‐plant SRC‐II reactor. The simulation shows that normal operations of the SRC‐II reactors are thermally unstable. Changes in the process conditions can be utilized to achieve thermal stability for the reactor at normal SRC‐II operating temperatures, i.e., reactor outlet temperature of less than 465°C and average reactor temperature of about 455°C. However, thermal stability of the reactor would always result in reduction in the rate of reaction. Regions of unstable steady‐state reactor temperature over large ranges of ash concentrations in the reactor and reactor feed temperatures are also illustrated.
Hydrolyse enzymatique du lactose dans un réacteur type réservoir agité
Authors: Ma Hung , Monsan P. , Mayer R. , Rouleau D. 
Published: March 2009

AbstractL'étude cinétique de l'hydrolyse enzymatique du lactose a été réalisée dans un réacteur agité de type réservoir en écoulement continu, dans des conditions isothermes pour des températures comprises entre 30° et 50°C pour un pH égal à 4.5. L'utilisation d'un panier contenant l'enzyme immobilisée, permet de réduire considérablement les résistances de transfert externe. L'enzyme utilisée provenant d'une souche d'Aspergillus Niger a été immobilisée sur des billes de silice. Les caractéristiques de mixtion parfaite du réacteur ont été confirmées par une étude hydrodynamique pour les mémes conditions opératoires. Une analyse statistique a été effectuée afin de différencier les modèles possibles et celui qui s'ajuste le mieux aux données expérimentales correspond au modèle de Michaelis‐Menten avec inhibition compétitive par le produit, le galactose:
The stability of a steam‐water front in a porous medium
Authors: De La Cruz V. , Spanos T. J. T. , Sharma R. C. 
Published: March 2009

AbstractWe present a first order stability analysis of a steam‐water front moving through a porous medium. The interplay between gravity, mobility and phase change are investigated. Several new phasical effects are observed in this dynamic study (e.g. oscillatory solutions, multiple solutions, etc.) and a number of specific limiting solutions are also considered.
Carbon number distribution of fischer — Tropsch CO‐hydrogenation products from precipitated iron catalysts
Authors: Egiebor N. O. , Cooper W. C. , Wojciechowski B. W. 
Published: March 2009

AbstractIt is shown that in a series of precipitated iron catalysts, some show a break in the Anderson‐Schulz‐Flory (ASF) plot of the distribution of linear products and others do not. It is also shown that the above break is due solely to the change in slope of the linear paraffins and that no such break occurs in the distributions of α or β‐olefins.Our conclusion is that the paraffins and olefins are all primary products and that each has a characteristic rate of termination, but all have a common rate of propagation. A growth scheme which explains our observations is presented.
Oxi‐ammoniation of pine‐bark particles
Authors: Coca J. , Alvarez R. , Fuertes A. B. , Alonso F. J. 
Published: March 2009

AbstractPine‐bark sawdust was oxidized with nitric acid (5‐20% by weight) and further ammoniated with NH3 or NH4OH. Ammoniation with NH3 was carried out in a fluidized bed reactor at 100 and 250°C and a NH, flow of 126 L/h (0°C; 101.3 kPa). Ammoniation with NH4OH was carried out in a batch reactor by reacting the oxidized sample with NH4OH (2 kmol/m3) at total reflux. Data on total nitrogen, ammonia nitrogen and KMnO4 soluble nitrogen content are reported for the resulting product.
A generalized solution method for the quasi‐chemical local composition equations
Authors: Abusleme J. A. , Vera J. H. 
Published: March 2009

AbstractThe work of Abusleme and Vera based on the Quasi‐Chemical Theory of Guggenheim in terms of groups is extended to multicomponent multigroup mixtures. The nonlinear equations arising from the theory are rearranged in a particular way that allows them to be solved using a generalized Newton‐Raphson method. Initial estimates of the values of the non‐random factors are obtained with a Taylor expansion around the random values. No more than five iterations are required for typical systems. Practical applications of the method are presented for ternary group systems.
Uniformity of fluidization on a multi‐orifice gas distributor
Authors: Baskakov A. P. , Tuponogov V. G. , Philippovsky N. F. 
Published: March 2009

AbstractAs the gas flow rate is increased through a bed of particles lying on a multi‐orifice gas distributor, several gas pressure maxima arise in the plenum chamber which correspond to the occurrence of fluidization in different sections of the bed. The gas pressure at the distributor orifices may considerably exceed the quantiy ρsg(1 − ϵ0)H. A formula has been derived for the complete‐fluidization index at which all caps come into play.
A stochastic model for the filtration of dilute suspensions using non‐woven cloths
Authors: Wilkinson E. T. , Davies G. A. 
Published: March 2009

AbstractA model is described to simulate a non‐woven unneedled fibre filter which describes the basic random structure of these materials. Good agreement is obtained between the observed structure of non‐woven filter fabrics and the predictions of the model. Data on the pore structure, pore area, perimeter and hydraulic radius can be predicted from the model.This description of a non‐woven filter is used in a stochastic trajectory model to calculate particle filtration. The analysis applies to filtration of dilute suspensions in the regime where particle screening is the predominant mechanism of filtration. The model predicts that the penetration into the filter decays exponentially with depth in the direction of flow. The interaction between the particle distribution on filter media (pore distribution) is taken fully into account in the analysis. The computational method allows the effect of particle size distribution on filtration efficiency, pore blockage and pore binding to be evaluated.
Study of complexing reactions causing the depletion of gadolinium ions from the moderator of CANDU‐PHW nuclear reactors
Authors: Gilbert Roland , Lépine Louis , Laurin Michel , Ouellet Lorenzo , Gauthier Rosanne 
Published: March 2009

AbstractThe addition of gadolinium nitrate solution in the moderator of Hydro‐Québec's Gentilly 2 reactor led to an unexpected depletion of gadolinium (Gd) by precipitation. Analysis of moderator samples revealed that bicarbonate (HCO3−) was the main anionic impurity. A study of the complexing reactions of Gd in concentrated solutions (0.0509M) of Gd(NO3)3 showed that in the absence of HCO3− and at pH < 6, the species in equilibrium are distributed as follows: predominant: Gd3+, NO3− and [GdNO3]2+; and traces: [GdOH]2+ and [Gd(NO3)2]+. An increase in pH over 6.4 led to the formation of the solid phase: Gd2(OH)5.1(NO3)0.9. In the presence of bicarbonate, the solid phase Gd2(OH)5.0(NO3)1.0 is visually detected at a pH as low as 5.8. In other respects, analysis of dilute solutions (0.00065M) of Gd(NO3)3 containing bicarbonate allows the solid phase precipitating between pH 5.5 and 6.6 to be ascribed to the formula Gd2(OH)4CO3·3H2O. In the absence of HCO3−, no precipitation occurred up to pH 6.8. Finally, the loss of Gd from the moderator was established as being due to the formation of a hydroxide carbonate salt.
Contacting modes and behaviour classification of gas—solid and other two‐phase suspensions
Authors: Grace John R. 
Published: March 2009

AbstractAn attempt is made to extend schemes for classifying the behaviour of gas—solid contacting modes and other two‐phase systems. The regime diagram approach of Reh (1971) is modified and extended to cover the operating regions of common reactors and contactors where a gas flows upwards through a bed of solids including fixed and moving packed beds, conventional fluidized beds, circulating beds, spouted beds, and pneumatically conveyed suspensions. New boundaries are proposed between groups A and B and between groups B and D of the Geldart (1972, 1973) powder classification scheme. These boundaries reflect more recent data and allow the classification scheme to be used for gases other than air and for temperatures and pressures other than atmospheric.
The permeability of fibrous porous media
Authors: Jackson Graham W. , James David F. 
Published: March 2009

AbstractThe literature was searched for experiments and theories related to low‐Reynolds‐number flow through fibrous porous media, particularly highly porous structures. Experimental data were found for a wide range of materials, from polymer chains to fiberglass, and the results collapse reasonably well when the appropriate dimensionless co‐ordinates are employed. Of the theories, accurate solutions of Stokes equation are available for regular arrays of parallel rods, either aligned with or normal to the flow. For irregular arrays and three‐dimensional media, approximate permeabilities can be calculated from several flow models.
The geometrical evaluation of effective diffusion coefficient in the liquid phase for porous bodies consisting of spherical elementary particles
Authors: Kobayashi Jun‐Ichi , Katsuzawa Hideo 
Published: March 2009

AbstractTo evaluate the intraparticle diffusion coefficient, De, of a component in a liquid, it was assumed that the pore structure of a porous catalyst was a space between an assembly of fine particles. This structure has been found for the metal oxide catalysts. The diffusivity ratio, δ (= De/D), was geometrically estimated in the direction normal to the representative plane (100), (110) or (111) of cubic closed, body centered cubic, simple cubic, or diamond packing of spherical elementary particles. The value δ was found to approximate the porosity ϵ. Larger pore constrictions gave smaller δ/ϵ values. Reaction rates were measured for the hydrogenation of nitrobenzene in ethanol. The efficiency of this evaluation of De was supported by the agreement of the experimental effectiveness factor with the theoretical factor.