bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prozessdatenvalidierung in der Rektifikation
Authors: Keller T. , Arlt W. , Paul A. , Bauer M. H. 
Published: March 2009

AbstractDie Bilanzierung stationärer Prozesse wie Rektifikationen führt oft aufgrund von fehlerbehafteten Messwerten zu nicht geschlossenen Massenbilanzen. Mit der Prozessdatenvalidierung steht ein statistisches Tool zur Verfügung, das aus den widersprüchlichen Messwerten den statistisch wahrscheinlichsten Prozesszustand ermittelt. Der vorliegende Beitrag zeigt die Vorgehensweise der Prozessdatenvalidierung einer Rektifikation unter Verwendung von Microsoft Excel.
Oxidation of low concentrations of hydrogen sulfide by air on a fixed activated carbon bed
Authors: Kaliva A. N. , Smith J. W. 
Published: March 2009

AbstractAs part of a study to evaluate the performance of a “dry” catalytic method of removing low concentrations of H2S from cupola gas, the rate of oxidation of low concentrations of H2S by air at room temperature has been studied using a fixed activated carbon bed. Previous studies have presented somewhat contradictory results.It was found that the rate decreased with time, consistent with a rapidly fouling catalyst, and finally attained a steady state value. A mechanism is presented which is in agreement with the results.The oxidation rate was also found to increase drastically by increasing the air humidity, contrary to the published results of some other workers.
Axial dispersion in gases flowing through small bore helical column
Authors: Singh P. C. , Singh S. 
Published: March 2009

AbstractThe results of an experimental study on the axial dispersion of gases flowing in helical columns under laminar flow conditions are reported. The ranges of variables covered are 26.6 < λ < 98; 10 < NRe < 100; 0.176 < NSc < 1.359. The measured dispersion coefficients are correlated with Reynolds, Schmidt and Dean groups. A single dimensionless parameter, NDc (NSe0,5, was found to correlate the data well. Up to NDe (NSc)0,5 =10, dispersions in straight and coiled tubes exhibit very similar axial dispersion behavior.
Numerical analysis of spouted‐bed hydrodynamics
Authors: Kürsad Dündar , Kilkis Birol 
Published: March 2009

AbstractSome of the basic concerns in the analysis of spouted‐bed hydrodynamics are the flow pattern and the pressure field of the fluid and the spout shape. These are closely related with other design concerns such as spoutability, minimum spouting velocity and maximum spoutable bed depth. A computer program was developed in order to determine the flow pattern, pressure distribution in the fluid phase and the spout shape for a given operational condition. The computer program relies upon a two region model with a spout and annulus element for an axisymmetric bed. The paper presents some results for grain drying beds and compares them with the existing experimental data qualitatively.
The axial dispersed plug flow model for continuous counter‐current adsorbers
Authors: Ruthven Douglas M. 
Published: March 2009

AbstractThe theoretical expression for the height equivalent to a theoretical plate is derived for a continuous counter‐current adsorber and compared with the expression for a chromatographic system. The ratio of these quantities is generally about 0.5 under practical operating conditions but the precise relationship depends on the Peclet and Stanton numbers as well as on the counter‐current flow ratio.
Vapor pressure and heat of solution of sulfur dioxide in 1‐methyl‐2‐pyrrolidone and its aqueous solution
Authors: Walker Richard J. , Schwartz Cecil H. , Wildman David J. 
Published: March 2009

AbstractA new method was developed to measure the vapor pressure of sulfur dioxide above various liquid absorbents. It was applied to pure 1‐methyl‐2‐pyrrolidone and its aqueous solution at 50°C to 91°C for SO2 loadings of 3.73 × 10 4 kg/kg to 2.16 × 10 −2 kg/kg. A chemical model was developed. The heat of solution was calculated from the dependence of the vapor pressure on temperature and was 3.98 × 107 J/kmol (exothermic) for pure 1‐methyl‐2‐pyrrolidone. The vapor pressures disagreed with the only previously published set of results but were confirmed by independent measurements with a gas chromatograph.
Flow and mixing in swirling flow in a sudden expansion
Authors: Hallett W. L. H. , Günther R. 
Published: March 2009

AbstractExperiments have been performed on swirling air flow in a sudden expansion in a model of a chemical reactor to study the effect of swirl intensity on flow and mixing. At the highest swirl tested a central recirculation zone was formed, while at swirl intensities below the critical value required for central backflow a precession of the flow was discovered in which the flow entering the expansion was deflected away from the axis of symmetry and caused to precess around it. The effect of these flow patterns on the mixing of a tracer gas with the main flow was studied by measuring both time‐mean values and turbulent fluctuations of the concentration. The time‐mean measurements indicated mixing at all swirl levels to be about equally fast, but measurements of fluctuation intensities showed a much higher unmixedness at low swirl, corresponding to the large‐scale motions of the precessing flow.
Tar sand extractions with microemulsions and emulsions
Authors: Sarbar Mohammad , Brochu Charles , Boisvert Michel , Desnoyers Jacques E. 
Published: March 2009

AbstractExtractions of bitumen from tar sands were studied in parallel with pseudo‐ternary phase diagrams for the dispersion of bitumen in microemulsions. The three components were an active mixture (aqueous solution of surfactant and cosurfactant), a cosolvent and bitumen. Both pure and commercial surfactants were investigated, and, in general, commercial surfactants were more effective than pure ones. There was general correlation between the dispersion phase diagrams and the extractions. The microemulsion using Dowfax 2A1 as surfactant was an exception, being quite effective as an extractant even though not much bitumen could be dispersed in it. Most experiments were made with 2‐butoxyethyanol (BE) as cosurfactant, although a few were also made with phenol and pyridine. The efficiency of the cosolvent decreased in the order toluene > naptha > kerosene. Except for the case where the surfactant was Atlas G3300, extractions were more effective at 80°C than 25°C. With anionic surfactants pH did not seem to have much effect on the extractions.
Direct contact heat transfer – a better way to high efficiency and compactness
Authors: Rao D. N. , Mohtadi M. F. , Hastaoglu M. A. 
Published: March 2009

AbstractA new concept in direct contact heat transfer is proposed which consists of carrying out combustion, and maintaining the resulting flame, directly within a flowing stream of water. The concept has been experimentally demonstrated in a prototype designed to handle 1200 kg/h of water. The system comes to steady state within 30 seconds. The process yields thermal efficiencies up to 97.5% and heat transfer coefficients up to 14 times those found in industrial spray tower contactors. The novel process possesses a great potential for industrial applications, such as process hot water supply, enhanced oil recovery using hot water, and compact steam generators.
Liquefaction behaviour of alberta subbituminous coals
Authors: Moschopedis S. E. , özüm B. 
Published: March 2009

AbstractSubbituminous coals from the major regions of Alberta were evaluated as feedstocks in a direct liquefaction process. Autoclave tests were based on a “two level factorial design” statistical analysis to obtain information on coal liquefaction characteristics. The strongest interaction is found between the liquefaction temperature and time.
Prospects for a high octane gasoline synthesis catalyst
Authors: Ahmad Adnan , Wojciechowski Bohdan W. 
Published: March 2009

AbstractThe thermodynamics of synthesis reactions relevant to the production of alcohols, aldehydes, olefins, paraffins and aromatics lead us to conclude that the direct synthesis of aromatics will be favoured at temperatures around 650 K. We also note that the exothermicity of such a synthesis will be some 20% lower than that in conventional Fischer Tropsch synthesis.
Fluid to particle heat transfer in fluidized beds of mixed‐sized particles
Authors: Chen Peishi , Pei David C. T. 
Published: March 2009

AbstractNew experimental work on fluid to particle heat transfer was carried out in a 13.3 cm diameter bed of narrow‐cut and mixed‐sized ferric oxide particles. It was shown that, the channelling effect should be considered for fine particle systems. A correlation including the channelling effect was obtained from the experimental results. The addition of coarser particles into the fine particle systems provides better fluidization behavior and results in an increase in fluid to particle heat transfer coefficient. The most effective content of coarser particles is about 25%, and the optimum particle diameter ratio is about seven.
Heat transfer from a heating helical coil immersed in a jet‐stirred vessel
Authors: Hsu Yung‐Chien , Shih Ruey‐Fwu 
Published: March 2009

AbstractHeat transfer coefficients for heating helical coils immersed in a jet‐stirred vessel have been investigated. Geometric factors, such as the tube diameter, the pitch of the helical diameter, the jet nozzle diameter and the turn‐down angle of the jet nozzle, have been studied. Four process liquids of quite different physical properties (water, 70% glycerin, isopropyl alcohol, and KSK oil‐260) have been used as the heating mediums. The correlation developed for these Newtonian liquids is similar to that obtained for vessels with conventional mechanical agitators. The jet power requirement was also obtained from experimental data.
Effect of surface resistance on gas absorption accompanied by a chemical reaction in a gas—liquid contactor
Authors: Asolekar Shyam R. , Desai Dilip , Deshpande P. K. , Kumar R. 
Published: March 2009

AbstractAn analysis of gas absorption accompanied by chemical reaction in the presence of interfacial resistance is presented. The analysis indicates that the effect of interfacial resistance on interphase mass transfer is significantly higher in presence of a reaction compared to the pure absorption case. For fixed values of surface resistance and contact time, the difference between the amount of gas transferred across the interface with and without surface resistance increases as the value of reaction velocity increases. For ranges of contact time and surface resistance of practical relevance, the influence of surface resistance is too high to be neglected while designing gas‐liquid contactors.
Isobaric vapor—liquid equilibrium in binary mixtures of m‐ and p‐xylenes with cyclohexene and cyclohexanone
Authors: Comelli Fabio , Francesconi Romolo 
Published: March 2009

AbstractThe vapor‐liquid equilibrium data of the binary mixtures of m‐ and p‐xylenes with cyclohexene and cyclohexanone are determined at P = 40 and 98.67 kPa. The systems show a nearly ideal behavior with no remarkable difference in the activity coefficients of m‐ and p‐xylenes. The experimental data are correlated by the Wilson expression.
Combined heat and mass transfer in free convection about a sphere
Authors: Hasan M. , Mujumdar A. S. 
Published: March 2009

AbstractCombined heat and mass transfer characteristics of laminar free convection flow about a sphere are studied analytically. The analysis assumes negligible interfacial velocities due to mass diffusion as well as insignificant diffusion‐thermo and thermo‐diffusion effects. The surface of the sphere is assumed to be at a uniform temperature and a uniform concentration. Boundary layer equations for the system are solved for the specific cases of convective diffusion of water vapor and naphthalene into air by the local similarity and the local nonsimilarity approaches. Numerical results of the local Sherwood number, the local Nusselt number and local wall shear stress obtained from the local nonsimilarity solutions are reported in a tabular form and the local similarity results are displayed graphically. In the analysis the cases of aiding and opposing thermal and concentration buoyancy forces are considered. Cumulative mass flow rates along with the dimensionless representative profiles of temperature, concentration and tangential velocities are presented for various combinations of parameters.
Catalytic cracking and skeletal isomerization of n‐Hexene on ZSM‐5 Zeolite
Authors: Abbot J. , Wojciechowski B. W. 
Published: March 2009

AbstractThe catalytic cracking and skeletal isomerization of n‐hexenes on 60/80 mesh ZSM‐5 zeolite were studied in the temperature range 350–405°C. By applying the time‐on‐stream theory, the products of the reaction were identified as primary, secondary or both according to their optimum performance envelope (OPE) curves on product selectivity plots.The products of cracking were found to be almost exclusively mono‐olefins and those in the range C3‐C5 were found to be stable primary, or primary plus secondary products. No C1 was found, and only traces of C2 as ethylene. The observed product distributions can be explained by a dimerization‐cracking mechanism with no product species having more than twelve carbon atoms. The probability of a fragment undergoing further cracking before desorption increased with temperature and the observed initial selectivities must be corrected to account for this process.Methylpentenes, formed as unstable primary products, were the main isomers produced by skeletal rearrangement, with those derived from more stable carbenium ions predominating.Paraffins, coke and aromatics were found in small amounts only.
Gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of pseudoplastic liquids
Authors: Hikita Haruo , Ishimi Kosaku , Koroyasu Sadatoshi 
Published: March 2009

AbstractGas absorption accompanied by an instantaneous irreversible chemical reaction into laminar falling films of power‐law liquids was studied theoretically. The convective‐diffusion equations for a solute gas and a liquid‐phase reactant were solved numerically and the numerical solution for the reaction factor was obtained as a function of the Graetz number, the concentration ratio, the diffusivity ratio and the power‐law index of the liquid.
Contribution à l'étude du transfert de chaleur à la paroi dans les récteurs à lit fluidisé gaz‐liquide‐solide à faible vitesse de liquide
Authors: Saberian‐Broudjenni M. , Wild G. , Midoux N. , Charpentier J. C. 
Published: March 2009

AbstractA study has been made of the wall to bed heat transfer in three‐phase fluidized beds with cocurrent upflow of the gas and the liquid, the liquid being the continuous phase. The experiments were done using five different liquids (tetra‐chloroethene, cyclohexane, kerosene, gas oil, water), three different kinds of particles (glass beads, porous alumina spheres and cylinders) at liquid velocities below 30 mm/s and gas velocities from 10 to 150 mm/s. The phenomena observed with a foaming liquid are described. Different literature correlations proved to be non‐applicable at the velocities used in this work; moreover, they are not able to take into account the influence of the nature of the liquid. Therefore, a new correlation which fits well our results is proposed. The areas requiring further investigation before a safe prediction of the wall heat transfer coefficient in three phase fluidized beds can be possible are detailed.
The correlation between the strength factor and the true tensile strength of agglomerate spheres
Authors: Wynnyckyj J. R. 
Published: March 2009

AbstractSpheres were produced from an iron‐ore concentrate by balling and subsequent shaping, and cylinders were cut from these spheres. Experimental data are presented, correlating the factor L/D2 for the spheres with the failure stress of the cylinders. The latter was measured by the diametral compression (Brazilian) test.The results confirm the direct proportionality between the two, but only above a minimum level of agglomerate matrix strength. At less than 120 kPa the relationship may become complex. A qualitative explanation is offered in terms of the stress‐deformation behaviour of the spheres and cylinders.
Performance of combined cobalt—nickel—zirconia and HZSM‐5 catalyst systems for carbon monoxide hydrogenation
Authors: Varma R. L. , Bakhshi N. N. , Mathews J. F. , Ng S. H. 
Published: March 2009

AbstractThe synthesis of hydrocarbons via hydrogenation of carbon monoxide was investigated over cobalt—nickel—zirconia catalysts of various compositions in combination with zeolite HZSM‐5 in “mixed bed” and “follow bed” arrangements. These combinations resulted in the formation of aromatics in amounts as high as 30‐35 wt% under relatively mild operating conditions (1 atm, 250–280°C). Although the olefinicity of C2 and C3 fractions in the product stream was higher in the mixed bed compared to the follow bed arrangement, the selectivities to aromatics were comparable in the two bed arrangements. The aromatic selectivity was found to be sensitive to operating conditions. The formation of aromatics was favored at high HZSM‐5/metal catalyst ratios, low space velocities and high reaction temperatures. The product distributions obtained using various metal/zeolite bifunctional catalysts have been discussed.
The effects of temperature on the partial wet oxidation of peat
Authors: Sheppard John D. , Robey Herbert L. , Mckim Mathew P. 
Published: March 2009

AbstractThe effects of three reaction temperatues, 180, 200 and 220°C, on the partial wet oxidation of peat were investigated. A stirred reactor with a five litre working volume and continuous feed of peat slurry and air was used for the experiments. The effluent was separated into liquid and solid fractions and analyzed to quantify the effects of temperature. The carbon content and heating value of the recovered solids increased with temperature but yields were lower. The composition of the wastewater was only slightly dependent on the reaction temperature, and in all cases contained high concentrations of organics.
Use of opposed jet flame stabilization in a downhole steam generator
Authors: Mohtadi M. F. , Sarkar S. 
Published: March 2009

AbstractUse of opposed jet flame stabilization in a direct contact steam generator which can operate in the borehole of an oil well was successfully demonstrated. Flame stabilization was obtained using a coaxially placed mixing cup from which a jet of premixed methane and air was introduced counter‐currently into the main air stream. Stable combustion was achieved within a wide range of air/fuel ratios. Steam generation rates of up to 75 kg/h, evaporation efficiencies of up to 92% and combustion intensities approaching 12 MW/m3 could be sustained over prolonged periods. A logic ignition control system ensured the safe operation of the generator. Exhaust gas analysis showed only negligible amounts of unburned methane and less than 0.5% carbon monoxide, when operating the generator at equivalence ratios of around 1.2.
Dynamic study and control of crystal size distribution (CSD) in a KCL crystallizer
Authors: Rohani S. 
Published: March 2009

AbstractPrevious works on crystal size distribution (CSD) control have indicated that a successful control scheme requires on‐line measurement of nuclei density. Such measurements can only be performed using an extremely expensive particle size analyzer. Besides the cost, the accuracy of such analyzers is restricted to low concentration slurries.In the present work an attempt is made to replace nuclei density by an alternative process variable which can be measured easily and inexpensively. Theoretical analysis of a KCl crystallizer shows that slurry density in the fines loop is an excellent substitute for nuclei density. Preliminary tests show that a turbidimeter can be used for measurement of slurry density in the fines loop.Proportional direct feedback control based on measurement of slurry concentration in the fines loop and manipulation of fines removal rate is shown to stabilize an inherently unstable crystallizer. The ability of the control scheme to suppress outside disturbances is also verified.
Fonctionnement hydrodynamique d'une cellule d'électrophorèse: Elements de calcul
Authors: Biscans B. , Bertrand J. , Sanchez V. 
Published: March 2009

AbstractL'électrophorèse à écoulement continu utilise un champ électrique pour séparer, selon leur mobilité, les constituants d'un échantillon introduit dans un fluide porteur. Au cours de cette séparation, des difficultés telles que l'électro‐osmose ou la convection thermique perturbent la qualité de la séparation.Cette publication analyse les divers paramètres influençant le fonctionnement hydrodynamique de la cellule d'électrophorèse. Les équations de modélisation et les conditions de frontières correspondantes, leur conditionnement et leur résolution par une méthode aux différences finies, conduisent à mettre en évidence l'effet des perturbations hydrodynamiques générées par un tel système.
Process safety management of a fuel gas conditioning facility using fault tree analysis
Authors: Stevenson Felicia D. , Maher Steven T. , Sharp David R. , Sloane Barry D. 
Published: March 2009

AbstractThis paper discusses a process hazard management study of a fuel gas conditioning facility based on stateof‐the‐art fault tree analysis techniques. This facility lowers the water and hydrocarbon dewpoints of a high pressure fuel gas exposed to frigid temperatures during distribution. Using hazards checklists and guidelines as well as internal reviews, various process hazards were identified for this facility. Computerized fault tree analysis techniques were used to identify the failure sequences which could lead to process hazards, and analysts used these results to evaluate the impact of specific hazards upon process safety. Through recommendations presented in the study, the facility owner gained an increased awareness of potential problems and made modifications to reduce the possibility of a hazardous condition and subsequent catastrophic failure.
Factors affecting the kinetics of the heterogeneous oxidation of ammonium sulfite
Authors: Ahmad Nadeem , Eroǧlu İinci̇ , Gürkan Türker 
Published: March 2009

AbstractAbsorption of oxygen into 0.09 – 0.7 M solutions of ammonium sulfite was measured by utilizing a stirred cell. The concentration ranges of the cobalt sulfate catalyst was 5.5 × 10−5 – 4.7 × 10−3 M and that of oxygen in the gas phase 21 – 100%. The theory of absorption with fast pseudo‐nth order reaction was used to find the order of intrinsic rate of reaction with respect to reactants and the catalyst. Above a critical sulfite concentration the order in sulfite is zero, in O2 is 0.4 – 1, and in CoSO4 is 1. Under those conditions a proposed reaction mechanism yields orders of zero, 1, and 1, respectively. Below the critical point the order in sulfite is 2, indicating that another reaction mechanism is applicable. Although an increase of the ionic strength enhances the reaction rate slightly, an increase of pH from 7.6 to 8.5 causes a 1.4 fold increase. Under oxidative conditions deactivation of the catalyst and insoluble precipitate formation is observed.
Influence de la coalescence électrostatique sur le débit d'une colonne d'extraction à mélangeurs‐décanteurs
Authors: Kumar Anil , Ansermet François , Hartland Stanley 
Published: March 2009

AbstractCe papier décrit les effets d'un champ électrique sur la coalescence d'une dispersion aqueuse formée lors de l'extraction du cuivre à l'aide des réactifs du type LIX*. Les résultats d'expériences en batch sont appliqués à une colonne de mélangeurs‐décanteurs de conception nouvelle (MIXET) pour en améliorer les caractéristiques hydrodynamiques. Les débits peuvent ětre augmentés jusqu'à 3.5 fois pour une vitesse de rotation constante (ou la vitesse de rotation augmentée jusqu'à 1.7 fois à débit constant) par application d'un champ électrique continu pulsé.