bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gasification studies of onakawana lignite
Authors: Furimsky Edward 
Published: March 2009

AbstractOnakawana lignite was gasified in air, steam and an air + steam mixture in a fixed bed reactor. The extent of devolatilization was determined by pyrolysis in nitrogen. The composition of products, expressed in terms of H2/CO ratio, was temperature dependent. The ratio decreased with increasing temperature. During steam gasification the ratio decreased from 4.6 to 2.6 when temperature increased from 700° to 990°C. The addition of air to steam resulted in a marked decrease of this ratio.Steam gasification reactivity of chars prepared from Onakawana lignite at 500°C and 800°C were studied in the temperature range of 650°C to 1000°C. The carbon conversion results were fitted into equations describing the continuous and shrinking core models. The char prepared at 500°C was much more reactive than the one prepared at 800°C. Product distribution expressed as the H2/CO ratio, was favourable in the temperature range.For comparison, the Kentucky #9 coal and chars derived from this coal were used as referee materials. The reactivity of these chars was markedly lower than that of chars derived from Onakawana lignite.
Application of lost‐product analysis to liquefaction processes
Authors: Leipziger Stuart , Huang Ching‐Chung 
Published: March 2009

AbstractThermodynamic analyses were carried out for a Linde process for liquefaction of propane and an Expander process for liquefaction of methane. Proposed process modifications increased the Linde process efficiency from 0.039 to 0.132 and the Expander process efficiency from 0.157 to 0.199. The second‐law technique employed was based on the concept of lost‐product which is defined for a fixed power input as maximum possible production rate minus actual production rate.
Water elutriators in materials recycling
Authors: Biddulph Michael W. 
Published: March 2009

AbstractThis paper describes the results of an experimental and theoretical study of a large water elutriator. The earlier eddy diffusion model (Biddulph, 1979) is extended to provide a simple representation of “wall‐flow” of particles. A reasonably good agreement with experimental separations of standard mixtures is achieved at water velocities of interest in the field of materials recycling. The model is used to explore some design parameters including feed location and length of column. The implications of separating mixtures containing a range of particle sizes and shapes is considered.
Peat char reactivity in CO2 atmosphere at high pressures
Authors: Fauteux D. , Chornet E. 
Published: March 2009

AbstractReactivities of peat char have been measured in CO2–N2 gas mixtures at temperatures ranging from 600°C and 900°C and pressures of up to 9.1 MPa using a fixed bed placed in a flow reactor. A semi‐empirical kinetic expression is presented which includes the temperature, CO2 pressure and variation in the specific area of the substrate. An Arrhenius equation is used to obtain an activation energy of 99.1 kJ/mol for the gasification process.
Isomerization of n‐hexane over nickel‐loaded zeolite catalysts
Authors: Jothimurugesan K. , Bhatia S. 
Published: March 2009

AbstractThe isomerization of n‐hexane to branched‐chain isomers was studied over various zeolite supports containing nickel between 1 to 5 wt%. NaA, NaY, CaY and Zeolon 900H were loaded with nickel by an impregnation technique. It was observed that at a nickel content of about 2.5 wt%, all the catalysts showed maximum activity for isomerization. A catalyst containing 1 wt% Ni/CaY gave the maximum selectivity among all the catalysts studied. Increasing the nickel loading beyond 2.5 wt% Ni with CaY and Zeolon 900H led to more hydrocracking. No major change in the activity and selectivity of Ni/NaA catalysts was observed beyond 2.5 wt% Ni, whereas the activity of Ni/NaY catalysts remained almost constant over the range of nickel content studied. A catalyst containing 2.5 wt% Ni on Zeolon 900H gave the maximum yield of isomers at 643°K. The apparent activation energy of the reaction was found to be 48.6 kJ/mol for 1 wt% Ni on Zeolon 900H catalyst.
Influence of carbon on iron in the hydrogenolysis of isopentane
Authors: Monnier Jacques , Dénès Georges , Anderson Robert B. 
Published: March 2009

AbstractThe influence of carbon on the selectivity and reaction rate of Fe catalysts in the hydrogenolysis of isopentane was studied at 325 and 355°C. Used catalysts, characterized by Mössbauer spectroscopy, contained α‐Fe at high feed ratios of H2 to hydrocarbon, and F3C, at low ratios. The formation of bulk iron carbides led to changes in selectivity, less methane and more intermediate hydrocarbons. A power rate expression was obtained for hydrogenolysis at 325°C.
Minimum spouting velocity of scaled‐up beds
Authors: Fane A. G. , Mitchell R. A. 
Published: March 2009

AbstractThis note presents the results for minimum spouting velocity in beds up to 1.1 m diameter. New evidence is provided that for fixed aspect ratio the minimum spouting velocity first falls and then begins to rise as bed diameter is increased. A simple correction factor applied to the Mathur and Gishler minimum spouting velocity correlation is required for beds ≥ 0.4 m diameter.
Hydrodynamics and mass transfer in a bubble column with an organic liquid
Authors: Godbole S. P. , Joseph S. , Shah Y. T. , Carr N. L. 
Published: March 2009

AbstractHydrodynamic and mass transfer data in Soltrol‐130 (a mixture of C9+ iso‐paraffins) were measured in a 0.305 m diameter bubble column. The gas holdup structure (i.e., the contributions to holdup from the small and large bubble fractions of the dispersion) for this hydrocarbon liquid in the churn turbulent flow regime was analyzed using the dynamic gas disengagement technique. The validity of the assumption of axially uniform gas holdup structure was checked. Literature correlations were found inadequate to explain the observed gas holdup and the volumetric mass transfer coefficients for Soltrol‐130. The volumetric mass transfer coefficient per unit volume of large bubbles is shown to be independent of superficial gas velocity for the fully developed churn turbulent regime. The present hydrodynamic and mass transfer data in the churn turbulent regime should be useful in the design and scale‐up of bubble columns used in organic process industries.
Mass transfer at geometrically dissimilar rough surfaces
Authors: Tantirige S. , Trass O. 
Published: March 2009

AbstractMass transfer rates at rough surfaces composed of V‐shaped grooves perpendicular to the direction of flow have been measured in a 25 mm square duct by an electrochemical technique. Roughness heights ranged from 50 to 700 μm, at various pitch/height ratios. The Reynolds number was varied from 2000 to 85,000, at Schmidt numbers of 1600 and 3600. Transfer enhancement depended on both size and shape of the roughness elements; rates four times greater than smooth surface values were observed.
Davy mckee combined mixer settler: Some laboratory studies
Authors: Rao N. V. R. , Baird M. H. I. 
Published: March 2009

AbstractA small (15 cm square) Davy McKee Combined Mixer Settler has been subjected to hydrodynamic and mass transfer experiments. These included measurements of pumping head, power dissipation, holdup, droplet size and mass transfer efficiency. It was found that the holdup in the dispersed region was in general not uniform, with slight dependence on agitator speed, phase flow rates, etc. The droplet sizes in the impeller region were correlated in terms of agitator speed and system properties. The mass transfer efficiency for the system water/n‐butyric acid/kerosene was affected by agitator speed, overall retention time, and the direction of mass transfer (to or from the dispersed phase). However, it was substantially unaffected by the ratio of phases fed.
Grinding of coal‐oil slurries with the szego mill
Authors: Papachristodoulou G. , Trass O. 
Published: March 2009

AbstractGrinding of coal in fuel oil for coal‐oil mixtures (COM) preparation is simpler and may give better slurry properties than dry grinding followed by dispersion in oil. A 42 weight percent slurry of 600–840 μm particles of Pittsburgh coal in #2, #4, and #6 fuel oils has been ground with the novel Szego mill. Particle size distributions at different residence times are reported down to a 10 μm median size, together with energy consumption data. Low mill hold‐ups and high rotational speeds enhanced the rate of grinding.
Oxidation of ethyl alcohol in trickle bed reactors: Analysis of the conversion rate
Authors: Baldi Giancarlo , Gianetto Agostino , Sicardi Silvio , Specchia Vito , Mazzarino Italo 
Published: March 2009

AbstractThe interpretation of results of a chemical reaction carried out in a trickle bed reactor is not immediate when the key reactants are volatile; in fact some authors state that the overall conversion rate increases at very low liquid flow rates, i.e. when the catalyst is unevenly wetted. In these conditions, the reactants may penetrate inside the catalyst pellets directly through the “dry” zones; therefore the mass transfer resistance is diminished and the conversion rate can be increased.To investigate this phenomenon tests on the catalytic oxidation of ethyl alcohol dissolved in water were performed at different operating conditions in a trickle bed reactor. An interpretation of the results was tried by using two different models based on partially wetted particles. This approach considers both the cases in which “dry” zones are active or not for mass transfer and mass transfer rates are affected or not by the chemical reaction.
Dynamic analysis of a fluidized bed reactor for sucrose inversion catalyzed by immobilized invertase
Authors: Doǧu Timur , Kaletunç Gönül , çaǧlar Arif 
Published: March 2009

AbstractAxial mixing characteristics and performance of a liquid fluidized bed reactor for the sucrose inversion reaction, which was catalyzed by immobilized invertase was studied. The invertase enzyme was immobilized in polyacrylamide gel by the bead polymerization technique. Well‐defined spherical gel particles of five different sizes (0.29–3.16 mm) were prepared. Efficiency of the immobilization technique, the optimum working conditions and the kinetic parameters were determined in a batch system. It is shown that as the particle size increases the rate of inversion first increases due to decrease of enzyme loss by leaching and then decreases because of diffusional limitations after a maixmum is reached. The performance of the fluidized bed reactor was investigated dynamically by introducing a step input of substrate at the inlet and analyzing the response curves. These experiments were performed at the optimum temperature (55°C) and using the optimum particle size (2.15 mm). The axial dispersion coefficient was found to increase from 0.45 to 1.26 cm2/s by changing the liquid velocity from 0.32 to 0.58 cm/s.
Fischer‐tropsch synthesis on a precipitated iron catalyst: Influence of silica support on product selectivities
Authors: Egiebor Nosa O. , Charles Cooper W. 
Published: March 2009

AbstractThe influence of silica support on the α‐olefins, internal olefins and branched hydrocarbon selectivities of the gasoline range products of a precipitated iron catalyst in the Fischer‐Tropsch synthesis was investigated. Three catalysts with varying silica content and constant promoter content were studied. It was found that there is a linear relationship between the silica content of the catalysts and the internal olefin and branched hydrocarbon product selectivities. The selectivities of the aromatic and alcohol products remain relatively constant, indicating that the production of these two groups of compounds is not affected by the presence of silica support in the catalysts.
Influence of forced cycling on the fischer‐tropsch synthesis. Part II. Response to feed concentration square‐waves
Authors: Feimer J. L. , Silveston P. L. , Hudgins R. R. 
Published: March 2009

AbstractThe influence of forced feed cycling was investigated on the product distribution from C1 to C9 of the Fischer‐Tropsch synthesis. A promoted iron catalyst in a small‐scale differential reactor at 246°C and 384 kPa total pressure was employed with square‐wave composition cycles generated at a constant flow velocity.Except for methane, the product distribution during feed composition cycling followed the steady‐state Schulz‐Flory model. For some combinations of period, cycle‐split and mean composition, the time‐average methane rate was higher than the corresponding steady‐state rate. Decreasing the period increased the time‐average rate both for methane and other hydrocarbon products. High methane rates, found only during a partial cycle with pure hydrogen, indicated that methane was probably being produced by a parallel reaction path, the hydrogenation of a surface carbide. The methane reaction rate via this mechanism should be strongly inhibited by CO.Product selectivity may be altered by forced composition cycling.
A study of the voltage and current efficiencies of fused salt AlCl3 electrolysis using bench scale cells
Authors: Hauksson Trausti , Foulkes Frank R. 
Published: March 2009

AbstractThe fused salt electrolysis of AlCl3 dissolved in LiCl‐NaCl melts at 700°C was studied using bench scale cells employing graphite electrodes. The effects of AlCl3 concentration, forced convection, interelectrode spacing, and current density on the voltage, current, and energy efficiencies of the process were investigated. At a practical cell voltage of 3.05 V and current density of 15 kA·m−2 the electrical energy consumption per kg of aluminum produced by the AlCl3 process was about 32 MJ, compared with a typical value of 52 MJ·kg−1 for the Hall‐Héroult electrolysis.
Isobaric vapor‐liquid equilibrium in mixtures of m‐and p‐xylenes with carbon tetrachloride
Authors: Francesconi Romolo , Comelli Fabio 
Published: March 2009

AbstractIsobaric vapor‐liquid equilibrium measurements on binary mixtures of m‐ and p‐xylenes with carbon tetrachloride were taken at P = 40, 66.67 and 98.67 kPa.The Wilson expression was used to correlate the experimental data. Only a weak deviation of the liquid phase from ideality is found. Activity coefficients of m‐ and p‐xylenes in carbon tetrachloride show negligible differences.
Computer simulation of fluid and plasma protein transport in the lungs
Authors: Bert Joel L. , Pinder Kenneth L. 
Published: March 2009

AbstractThe mass transfer of fluid and plasma proteins from the blood to the lung tissue and then to the lymphatics was studied using computer simulations. Emphasized were the effects of perturbations in pressure and permeability on the transient and steady state response of the system. Trends with regard to fluid accumulation in lung tissue and sieving of plasma proteins between blood and lymph for isolated and combined perturbations of pressure and permeability are discussed.
Optimization by lumped control of reactors with langmuir‐hinshelwood catalyst deactivation
Authors: González‐Velasco Juan Ramón , Gutiérrez‐Ortiz Miguel Angel , Salvador Arturo Romero 
Published: March 2009

AbstractA method is proposed for solving the problem of temperature optimal control in tubular fixed‐bed reactors with reaction systems described by Langmuir‐Hinshelwood‐Hougen‐Watson kinetic equations. The optimization problem is formulated by N state differential equations corresponding to the N differential fixed‐bed reactors in which the integral reactor is divided. It is solved using the control vector parameterization computational technique. The proposed method when applied to a simple reaction system reported previously in the literature gives analogous results, and thus validates the theory. This theory is applied to the dehydrogenation of benzyl alcohol to benzaldehyde. An analysis of optimality problem shows a strong influence of the temperature dependence of the ratio of reaction rate to deactivation reaction rate on the optimal policy.
Evaluating errors in chemical plant mass balance
Authors: Tinè C. B. D. 
Published: March 2009

AbstractBased on known techniques a simple procedure is developed for adjusting the measured flow rates of the various species entering and leaving a chemical process so as to satisfy the mass conservation equation. The procedure takes into account the error variance of the measurements of any physical quantity involved in the balance. The procedure has been applied to correct the material balance of an industrial catalytic reforming plant where it has been useful in providing a precise evaluation of the process performance and in estimation of the catalyst regeneration time. The procedure may also be used for component or energy balance around a chemical process.
Effects of interaction between circulating or oscillating droplets on drop formation, free fall, and mass transfer
Authors: Skelland A. H. P. , Vasti Nicholas C. 
Published: March 2009

AbstractThe effects of interaction between circulating or oscillating droplets on drop formation, terminal velocity, and the continuous phase mass transfer coefficient during free fall were studied. To examine the mass transfer coefficient during free fall both end effects were eliminated by subtracting the mass transferred in a short column from that transferred in a long column. A correlation for the prediction of drop volume based on the equations of Scheele and Meister (1968) for non‐jetting drops, and of Meister and Scheele (1969a, 1969b) for drops formed under jetting conditions, has been developed. The terminal velocity of the drops was enhanced by vertical interaction with adjacent drops at values of L/dp < 5. The continuous phase mass transfer coefficient for circulating drops was reduced due to vertical interaction at L/dp < 10; however, for slightly oscillating drops it was not affected by vertical interaction over the range of 1.5 < L/dp < 20. By conducting experiments with single and triple nozzle arrangements, horizontal interaction effects were found to be negligible for both systems.
Analysis and performance of a V‐trough solar concentrator
Authors: Hadi M. Issa Abdul 
Published: March 2009

AbstractA thermal analysis of the V‐trough solar concentrator for use in solar heating and cooling is presented. A compact analytical expression for estimating Solar Insolation received by a collector for any day with any sky conditions has been formulated. The estimated values are found to be very close to quantities recorded by solar radiation measuring instruments. The V‐trough concentrator was investigated experimentally and found to be more efficient than a flat plate collector. It provided temperatures higher than 90°C. It is thus more suitable to utilize in absorption refrigeration applications.
Réacteurs de trempe dans les procédés chimiques à haute température. Application à la thermolyse de l'eau
Authors: Lapicque F. , Lede J. , Villermaux J. 
Published: March 2009

AbstractThis paper describes the modelling of a hydrogen production process by direct splitting of water in a dissociation reactor in which the high temperature reaction occurs, followed by quenching with gaseous jets to recover the hydrogen produced. Proposed models, dealing with the dissociation reactor and principally with the two designed quenching devices, take into account the various physicochemical phenomena (heat transfer, complex chemical reaction, gas mixing). The quenching rate (up to 106 K/s) and theoretical gas composition at the outlet of the overall reactor can be calculated in a fairly good agreement with experimental results.
Studies on mass transfer during drop formation in a pulsating gaseous medium
Authors: Guha D. K. , De P. 
Published: March 2009

AbstractTheoretical and experimental investigations have been carried out for the mass transfer to an internally circulating drop forming in a continuously pulsating gas‐phase. Enhancement in mass transfer rate of about 200% has been achieved by increased internal circulation within the large‐sized drop during its formation, through pulsations in the gas‐stream. Effects of pulsation parameters on the overall mass transfer rate have been investigated. The experimental and computed data have also been compared for both the cases of physical absorption and absorption accompanied by fast, irreversible pseudo‐first order chemical reaction. Data show a good agreement for the two systems studied, the agreement being particularly good for the reacting system.
Control of foaming in hydrogen sulfide/water mixtures
Authors: Spagnolo D. A. , Chuang K. T. 
Published: March 2009

AbstractHydrogen sulfide/water mixtures are frequently encountered in the petrochemical and heavy water industries. Such mixtures exhibit an inherent foaminess when operating close to the liquefaction pressure of H2S. This can cause severe problems in fluid handling equipment.Some nonionic surfactants are effective antifoams for these mixtures. The antifoam action is due to surfactant micelle formation which is enhanced by the presence of H2S through a “salting out” mechanism. The pressure at which a particular surfactant becomes an antifoam can be predicted from the hydrophobicity of the surfactant molecule. Such understanding could be applied to control foaming in other systems.
Prediction of operating range of rotor speeds for rotating disc contactors
Authors: Kamath M. S. , Subba Rau M. G. 
Published: March 2009

AbstractThis paper reports on the optimum range of rotor speeds for the operation of Rotating Disc Contactors (RDC). New information based on experimental investigations is presented regarding the existence of a second critical rotor speed which divides the varying characteristic velocity region into rapidly varying and gradually varying characteristic velocity regions of the dispersed phase droplets. New modifications to the reported generalised correlations for the prediction of characteristic velocity at all rotor speeds under conditions of no solute transfer as well as solute transfer between dispersed and continuous phases are suggested.
Upgrading of aspen poplar wood oil over HZSM‐5 zeolite catalyst
Authors: Mathews J. F. , Tepylo M. G. , Eager R. L. , Pepper J. M. 
Published: March 2009

AbstractThermally fractionated components of an oil prepared by the liquefaction of aspen poplar wood have been upgraded using a HZSM‐5 zeolite catalyst to yield products rich in benzene, toluene, xylenes and higher molecular weight aromatics. The effect of reactor temperatures on the relative abundance of these products has been studied.
Estimating friction factors in a fouled annulus
Authors: Melo L. F. , Pinheiro J. D. 
Published: March 2009

AbstractFouling of heat transfer surfaces modifies the associated conductive thermal resistance and convective heat transfer coefficient. Often, the latter varies as a result of changes in the roughness of the deposition surface. If fouling is being studied in an annular heat exchanger, deposits may form on both surfaces of the annular cross section, and an estimation of the friction factors of each fouled surface is needed. In order to evaluate these factors a simple method can be used as described in this paper, based on pressure drop measurements and current equations. Experimental results are reported and appear to support the method.