bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on chains of bubbles rising through quiescent liquid
Authors: Miyahara Toshiro , Kaseno Satoru , Takahashi Teruo 
Published: March 2009

AbstractThe liquid velocity profile induced by a chain of bubbles is studied theoretically and a comparison with measurements is made. The wake velocity and the bubble shape involved in the theoretical development are considered based on the wake theory and the previous empirical relation for single bubbles, respectively.The shape and wake volume of chain bubbles can be treated in the same manner as those of single bubbles by using relative velocity. As a result, using the previous results of the drag coefficient and shape of single bubbles enables the prediction of the rising velocity of chain bubbles.
Gas absorption in laminar falling films of pseudoplastic liquids
Authors: Hikita H. , Ishimi K. , Hara M. , Matsunami T. 
Published: March 2009

AbstractGas absorption into laminar falling films of power‐law liquids was studied theoretically and experimentally. The convective‐diffusion equation was solved by the method of separation of variables and the analytical solution for the average Sherwood number was obtained as a function of the Graetz number and the power‐law index of the liquid. Experiments were carried out on the absorption of pure carbon dioxide, hydrogen and helium into aqueous kaolin slurries by using a long wetted‐wall column and the average absorption rates were measured as a function of the mass flow rate of the liquid. The experimental results were in good agreement with the theoretical predictions.
A classification of fischer–tropsch synthesis product distributions
Authors: Egiebor N. O. , Ungar K. R. , Wojciechowski B. W. 
Published: March 2009

AbstractTwo types of product distributions in Fischer–Tropsch synthesis have been observed; the “classical” distribution where successive carbon numbers contain homologous groups of compounds and the “non‐classical” where the product spectrum deviates from the above picture. It is proposed that the non‐classical distributions arise on bifunctional catalysts on which primary synthesis products are rapidly converted to isomeric secondary products.
Errors associated with the measurement of dew‐point loci for wide boiling mixtures
Authors: Veeranna Doddipatla , Husain Asghar 
Published: March 2009

AbstractThe normal practice to measure the dew‐point locus of a mixture is to use a static phase equilibrium still. In this technique, the condensate needed to observe cloud formation completely changes the composition of the mixture, leading to inaccurate dew‐point measurements. A careful analysis is made in this work to show the extent of the error in the dew‐point measurement using the static phase equilibrium still.
Grid leakage (weeping and dumping) in a pilot plant size gas fluidized bed
Authors: Briens C. L. , Bergougnou M. A. 
Published: March 2009

AbstractSubstantial grid leakage in large industrial fluidized beds is highly undesirable because it can lead, among other things, to grid erosion or plugging. Experiments have been carried out to study grid leakage using a cracking catalyst (arithmetic mean diameter 65 μm) in a 0.6 m diameter column. The flow pattern under the grid was charted with a hot wire anemometer. Micro‐isokinetic probes were developed to study the particle flux returning from the windbox towards the grid. Particles were sucked in isokinetically, recovered in a filter, weighed and analyzed for particle size in a Coulter counter. Upward particle fluxes at the grid were determined by extrapolation of the flux at various distances below the grid. Grid leakage was studied for grids of various geometries which had holes of 1.27 cm diameter. Various measurement methods, a model for re‐entrainment and correlations are given.
A new lubricants extraction process
Authors: Sankey B. M. 
Published: March 2009

AbstractDevelopment of a new process for the solvent extraction of lubricating oils, known as EXOL N, is described. The selection of N‐methyl‐2‐pyrrolidone (NMP) as solvent, the determination of its relevant properties, and its application through engineering and pilot‐plant studies are reviewed. This EXOL N process is now employed internationally in over a dozen full‐scale lube extraction plants.
Flow patterns for cylinders immersed in an aerated vibrated bed
Authors: Malhotra K. , Mujumdar A. S. 
Published: March 2009

AbstractPressure drop measurements and results of an extensive flow visualization study to examine the particle‐free air gap formation around horizontal, rigidly‐mounted circular cylinders in a two dimensional vibrated bed, are presented. Effects of particle size and surface stickiness as well as other key operating parameters viz. aeration rate and vibrational frequency were examined for single as well as multiple cylinder configurations in staggered and in‐line arrangements.
Multidimensional heat, mass and flow phenomena in gas stirred reactors
Authors: Salcudean M. , Lai K. Y. M. , Guthrie R. I. L. 
Published: March 2009

AbstractComputations are presented for multi‐dimensional flows in gas‐stirred liquids contained in vertical cylindrical vessels. Mass, momentum, energy and concentration equations were solved for the buoyancy driven transient flows under investigation. Turbulence was simultated by using zero order and differential models of turbulence. The use of convective and diffusive time scales was analyzed. Reasonable agreement with available experimental data was observed.
Pyrolysis of western canadian coals in a spouted bed
Authors: Jarallah A. , Watkinson A. P. 
Published: March 2009

AbstractCoal pyrolysis has been studied to determine conditions for maximum liquid yields from some Western Canadian coals. Gas, tar and char yields were determined for four coals in a 12.8 cm dia. reactor. A characteristic temperature for maximum tar yield existed for each coal at a fixed feed rate and particle size. A steady increase in tar yield was found as the average coal particle size was reduced from 2.28 to 0.65 mm. Composition of gas, and ultimate analyses of tar and char are presented as a function of operating temperature. A simple first‐order devolatilization model adequately describes the effects of coal feed rate, reaction time, and temperature on the yield of volatiles, but is insufficient to describe particle size effects.
Catalytic cracking and skeletal isomerization of n‐hexenes on HY zeolite
Authors: Abbot J. , Wojciechowski B. W. 
Published: March 2009

AbstractThe catalytic cracking and skeletal isomerization of n‐hexenes on 80/100 mesh HY zeolite has been studied in the temperature range 350–405°C, and compared with results previously obtained on ZSM‐5 zeolites.Species with less than three carbon atoms were not observed as primary cracking products, with traces of ethylene formed only as a secondary product. Although propylene and propane may be formed partially by monomolecular cracking of n‐hexenes, the dominant cracking process is bimolecular. Dimerization, followed by disproportionation gives stable C3, C4 and C5 species, in addition to C9, C8 and C7 fragments. The probability of these larger fragments undergoing further cracking before desorption increases with temperature, but is significantly less than found on ZSM‐5 zeolites.The main products of skeletal isomerization were monomethylpentenes, with those isomers which can originate from tertiary carbonium ions dominant. Dimethylbutenes were formed mainly as secondary products.The rate of the dimerization‐cracking process in which two n‐hexene species participate is ⋍ six times slower than the reaction involving a monomethylpentene species and a linear hexene. The increase in the rate of the latter process with respect to the former is reduced on ZSM‐5, and this can be attributed to the narrower pore size within this zeolite.In contrast to ZSM‐5, there is significant formation of alicyclics, paraffins and aromatic species. The residual coke was found to be considerably poorer in hydrogen content than comparable material formed on ZSM‐5.
The dissolution of activated titanium slag in dilute sulfuric acid
Authors: Toromanoff Ivo , Habashi Fathi 
Published: March 2009

AbstractFinely ground titanium slag (–400 mesh) dissolves slowly in dilute H2SO4 (2–10 mol/L) in the temperature range 70–110°C, but attrition ground slag dissolves much faster under similar conditions. The process is strongly dependent on the speed of agitation in the region 345–1035 rpm, and has an activation energy of 28 kJ/mole TiO2, thus suggesting that the dissolution is controlled by diffusion through the boundary layer.
Particle residence times in the continuous spouting of mixtures
Authors: Cook H. H. , Bridgwater J. 
Published: March 2009

AbstractA magnetic labelling technique has been used to examine particle residence time distributions in a continuous spouted bed. For a single particle species, the nearly perfect mixing observed found by others is confirmed. For a binary particle system, perfect mixing of each component is found, but the mean residence times are not equal. The ratio of mean residence times is found to be dependent on the fountain height and bed depth; the influence of some of the underlying physical mechanisms in the fountain, free surface and outlet regions can be seen.
Simulation of discontinuous population balance equation with integral constraint of growth rate expression
Authors: Chang Rong‐Yeu , Wang Maw‐Ling 
Published: March 2009

AbstractAn effective method based on the concept of continuous characteristics is developed to solve the continuous population equation with integral constraint of growth rate expression. This method can also be extended to solve a general form of a first order partial differential equation. A typical example of a class II MSMPR crystallization process at transient state is modelled and analyzed. The system which possesses originally a discontinuous population density function is transformed into a continuous one by appropriate treatment of the initial condition. The partial differential equation of the continuous population density function is solved by the shifted Legendre polynomials approximation and moments method simultaneously. The original discontinuous population density function is then transformed back from the calculated continuous one by the system characteristics. Very satisfactory computational results are obtained.
The thermal decomposition of granular and fluid soybean lecithins
Authors: Ross Robert A. , Lemay Réjean , Takacs Aniko M. 
Published: March 2009

AbstractThe effect of heat on the decomposition of two grades of soybean lecithin has been examined up to 600°C using differential scanning calorimetry and thermogravimetry. Studies were carried out in both air and argon and a kinetic analysis of the isothermal rates of reaction was attempted. Three principal decomposition stages were distinguished in argon and four in air for a water‐dispersible lecithin typical of the quality of the material used in many industrial applications. Gas chromatography showed that the principal gases evolved from 50 to 600°C in argon from the water‐dispersible lecithin in contact with aluminum surfaces were C1‐C6 hydrocarbons, carbon dioxide, carbon monoxide, water and traces of hydrogen.
Operating behaviour and crystallization mechanism of a sodium sulphate sodium phosphate mixture in a heat storage system
Authors: Fouda A. E. , Capes C. E. , Nakamura M. 
Published: March 2009

AbstractThe operating behaviour of a new salt hydrate mixture in a pilot heat storage unit using direct contact heat exchange has been investigated. The new storage medium is based on diluted Glauber's salt in which the excess water has been replaced by Na2HPO4 ṁ 12H2O as an active participant in the storage process.Improved heat storage properties have been found with the new salt mixture. Sampling of the salt solution and deposited crystals during operation indicated that alternate independent crystallization of Glauber's salt and of the phosphate salt occurs. Simulations of the crystallization behaviour based on this assumed mechanism are described.
Modelling glucose/fructose isomerization with immobilized glucose isomerase in fixed and fluid bed reactors
Authors: Beck M. , Kiesser T. , Perrier M. , Bauer W. 
Published: March 2009

AbstractImmobilized glucose isomerase is used to convert glucose to fructose in the production of “High Fructose Corn Syrup (HFCS)” by enzymatic starch hydrolysis. A reactor model was established analogous to heterogeneous catalytic reactor models, taking into account the effects of fluid/particle mass transfer, intraparticle transport, fluid bed expansion, backmixing and reversible kinetics. The kinetic data either for free enzymes and the biocatalyst particles were evaluated using laboratory scale stirred tank reactors. Fixed‐and fluid bed reactor experiments were performed. The comparison of calculated and experimental data show some deviation indicating that the correlations for mass transfer and back‐mixing for complex media, as used here, have to be checked.
Functional design of activated sludge processes with heavy metal inhibition
Authors: Tyagi R. D. , Couillard D. , Villeneuve J. P. 
Published: March 2009

AbstractBased on a laboratory study of simulated synthetic waste, a kinetic model to describe the inhibitory effects of heavy metals on growth of microorganisms during the activated sludge process was developed. The kinetic equation involves the four biokinetic constants, μm, Ks, Kd and Y, and the two metal inhibition constants, n and c, which are respectively characteristic of a specific wastewater and the metals in question. The two control variables, cell recycle ratio and cell concentration in the recycle stream, can be used to minimize the inhibitory effects without increasing either the volume of the bioreactor or the residence time.
A comparison of the energy and product distribution from biomass gasifiers
Authors: Esplin G. J. , Fung D. P. C. , Hsu C. C. 
Published: March 2009

AbstractA detailed analyses of the raw producer gas streams generated by a downdraft gasifier and by a fluidized‐bed gasifier are presented and are discussed in terms of raw gas clean‐up considerations and of energy conversion efficiency.The major gasifier operating parameters such as fuel/air ratio, carbon conversion efficiency, net energy conversion efficiency, and producer gas heating value are then compared between seven operational gasifiers and a computer simulation model of a fluidized‐bed gasifier developed by Queen's University.It is concluded that the Queen's University model correctly predicts that the fuel/air ratio is the single most important parameter for determining gasifier performance. Downdraft gasifiers exhibit superior energy conversion efficiency and producer gas quality because they utilize a higher fuel/air ratio than do fluidized bed gasifiers.
Hydrodynamique des contacteurs gaz—Liquide du type venturi à émulsion fonctionnant en autoaspiration
Authors: Labit C. , Lebeault J. M. , Zoulalian A. , Besson G. 
Published: March 2009

AbstractLes contacteurs gaz–liquide du type venturi à émulsion peuvent ětre employés comme élément de transfert d'oxygène dans un bioréacteur.Pour un fonctionnement du dispositif en autoaspiration, l'extrapolation nécessite la connaissance du débit gazeux autoaspiré en fonction de certains paramètres géométriques et opératoires.À partir de mesures hydrodynamiques effectuées sur trois Venturis de diamètres de col différents, nous proposons une méthode expérimentale d'extrapolation permettant, pour un venturi de géométrie donnée, de calculer le débit gazeux autoaspiré en fonction du débit liquide recirculé.
Fischer—tropsch studies on a plasma‐sprayed iron catalyst in a tube‐wall reactor
Authors: Kapoor A. , Goyal S. K. , Bakhshi N. N. 
Published: March 2009

AbstractConversion of synthesis gas to gaseous and liquid fuels via Fischer–Tropsch (FT) synthesis is becoming increasingly important for future energy needs. Tube‐wall reactors (TWR) are gaining importance for FT synthesis because of simple construction and improved temperature control. In the literature, studies have been reported on the FT synthesis in a TWR using a flame‐sprayed iron catalyst. In the present work, we have examined the effect of temperature (250–275°C), pressure (3.45 × 105 – 6.89 × 105 Pa), exposure velocity (0.61 – 2.44 m3/h of gas at STP/m2 of catalyst superficial area) and feed composition (H2/CO ratio of 2 and 3) on the product yield and selectivity using a plasma‐sprayed iron catalyst in the TWR. The plasma‐sprayed iron catalyst gave slightly lower conversions but showed much higher C5 + product selectivity as compared to the flame‐sprayed catalyst. The product distribution shifted towards higher hydrocarbons at lower temperatures, higher pressures and lower exposure velocities. The product distribution followed Shultz‐Flory relationship and the chain growth probability factor α decreased slightly with increase in temperature. The catalyst also showed good regeneration characteristics.
Cyclic gasification of coal in a moving bed. A bench scale study
Authors: Parés José A. , Rodríquez Daniel A. , Gordon Alfredo L. 
Published: March 2009

AbstractIn an experimental gasifier with 3 kg/h of conversion capacity, studies were made in order to get experimental data on the production of combustible gas from coal by a cyclic gasification process. The material and energy balances and the composition data are presented for 8 runs gasifying coke or coal. An acceptable reproducibility of data was observed. It is possible to obtain a fuel gas with a high calorific value of 10 MJ/m3 using air.
Viscosity of compressed athabasca bitumen
Authors: Mehrotra Anil K. , Svrcek William Y. 
Published: March 2009

AbstractNew data for the effect of pressure and temperature on Athabasca bitumen viscosity are presented. The viscosity data cover a temperature range of 43–120°C and pressures up to 10 MPa. It is shown that the compression of bitumen results in a significant increase in its viscosity but only a small increase in its density. Also presented are correlations that include the effect of pressure and temperature on the viscosity of the bitumen.
Vented combustion of hydrogen—oxygen—diluent mixtures in a large volume
Authors: Kumar R. K. 
Published: March 2009

AbstractCombustion of hydrogen‐oxygen‐diluent mixtures was carried out in a 2.3‐m‐diameter sphere with venting to a cylinder of 10.3‐m1 volume. It was found that stoichiometric hydrogen‐oxygen mixtures with helium as the primary diluent led to detonation for all hydrogen concentrations above 20% by volume. Addition of small amounts (5 to 10%) of a secondary diluent such as carbon dioxide or steam suppressed detonation. Carbon dioxide, because of its higher molecular weight, was found to be a better detonation suppressant than steam. Transition to detonation was more difficult to achieve at 100°C than at room temperature.
The mode of combustion of coal in a fluidised bed
Authors: Tomeczek Jerzy , Remarczyk Leonard 
Published: March 2009

AbstractIn this paper investigations of the mode of combustion of coal char in a fluidised bed at temperatures of 973–1173 K are presented. A reactor of 80 mm diameter has been continuously fed with particles of three different size ranges: 0.5–1.0 mm, 1.0–2.0 mm and 2.0–3.0 mm. Carbon loadings were in the range 20–60%. It has been shown that the particles of coal and of partially devolatilized char combust in the form of a shrinking sphere.
Prediction of drop size in rotating disc extractors
Authors: Kumar Arun , Hartland Stanley 
Published: March 2009

AbstractBased on published drop size data in the absence of mass transfer, two equations for the prediction of drop diameter with a break‐point at disc Reynolds number equal to 50 000 are presented which predict the drop diameter to within 14%. The total range of disc Reynolds number covered is 1200 to 282 000. The same equations may be used when mass transfer occurs if only the preconstants are modified. The ranges of disc Reynolds number covered are 28 000 to 434 000 for transfer from the continuous to the dispersed phase and 9300 to 290 000 for transfer from the dispersed to the continuous phase, the average absolute relative deviation being 11% in both cases.
High resolution measurement of particle velocities in a spouted bed using laser‐doppler anemometry
Authors: Boulos M.I. , Waldie B. 
Published: March 2009

AbstractA novel means of measuring particle velocities in spouted beds using laser‐doppler anemometry (L.D.A.) is described. L.D.A. is applied mainly in a back‐scatter mode to the spout and fountain of a half‐section bed. The fountain of a three dimensional bed can also be studied. L.D.A. is shown to be a powerful tool for measuring particle velocities in spouted beds. Statistically significant quantities of data are obtained with much higher resolution and in time scales orders of magnitude lower than with previous techniques. Previously unresolved aspects of particle motion, including wall effects in half‐section beds, can be quantified.
Hydrogenation of benzene, mono‐, di‐, and trimethylbenzenes over nickel catalysts supported on porous glass
Authors: Takahashi Takeshige , Yamashita Koji , Kai Takami , Fujiyoshi Issei 
Published: March 2009

AbstractThe hydrogenation of benzene and methyl‐benzenes was performed over a nickel catalyst supported on the porous glass prepared from borosilicate glass with an alumina content ranging from 3% to 5%. The micropore size of the porous glass decreased with increasing alumina content. Although the overall reaction rates of benzene and toluene did not significantly change with the alumina content in the borosilicate glass, the rate of 1,3,5‐trimethylbenzene, which is the bulkiest molecule among the hydrocarbons tested, decreased as the content of the alumina in the support increased. This result indicates that a catalyst support with molecular shape selectivity can be prepared from borosilicate glass containing alumina.
A finite element model of the ventilation pattern inside an industrial building I: Isothermal case
Authors: Tanguy P. A. , Dupuis M. 
Published: March 2009

AbstractA numerical simulation of the air flow pattern in a building at constant temperature having several openings for air inlet and a chimney is presented. The modelling is based on the use of a Galerkin‐Uzawa finite element method (FEM) with quadratic elements, for reliability and cost‐effectiveness. Four different cases of ventilation conditions are investigated. Numerical results are compared to existing finite difference predictions and experimental data, and exhibit a noteworthy agreement.
A recycle reactor for measuring hydrogen isotope exchange kinetics under vapour phase and trickle bed conditions
Authors: Suppiah S. , Chuang K. T. 
Published: March 2009

AbstractA recycle reactor system has been developed to measure the activities of catalysts for isotope exchange between hydrogen gas and water vapour. To allow testing of reasonably large quantities of catalysts, the reactor was operated with a high recirculating flow of hydrogen gas passing through a saturator to provide the water vapour required for the reaction. In this mode of operation, only a small spiking gas flow was required as feed compared to the very high feed flow that would be required for once‐through operation. The reactor was also operated as a trickle bed by recirculating the saturator water. By testing catalysts under both vapour and trickle bed modes, it was possible to investigate the effect of trickling water over the catalyst on the catalytic activity.Kinetic exchange rates under vapour phase operation were calculated from both plug flow and well‐mixed reactor models. The former model was found to be the appropriate one for the ranges of operating conditions investigated. However, for trickle bed operation, the well‐mixed reactor model was found to be the suitable one.Vapour phase and trickle bed tests done with random bed and structured bed catalysts indicated that the gas phase isotope exchange reaction was not impaired by the presence of liquid water in the reactor.