bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for bulk‐phase nitrogen dissolution in iron in catalytic ammonia synthesis
Authors: Jain A. K. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractExperiments were carried out in which the reactants, nitrogen and hydrogen were admitted to a fixed bed of triply‐promoted iron catalyst in the form of concentration step‐functions. Temperature was about 400°C, and total pressure was 2.38 MPs. The bed was stabilized with equimolal flows of hydrogen and nitrogen and then stepped up to pure hydrogen or down to pure nitrogen. From the rate of ammonia production, catalyst properties, and bed temperature behaviour, it was inferred that nitrogen is dissolved by the bulk phase of the iron catalyst. This result has important implications for a general model of transient and forced cyclic operation of catalyst beds.
Stabilization and destabilization of mineral fines‐bitumen‐water dispersions in tailings from oil sand extraction plants that use the hot water process
Authors: Hall E. Stanley , Tollefson Eric L. 
Published: March 2009

AbstractEffects of acid and polyvalent cations on flocculation and settling of tailings dispersions from an oil sand extraction plant are used to develop a model for previously puzzling pH dependent aspects of the hot water process. The model features calcium‐bicarbonate surface complexes that reduce mineral fines‐bitumen interactions, destabilize bitumen‐water emulsions and enhance attachment of air bubbles to bituminous surfaces. Protonation of bicarbonate allows agglomeration through formation of calcium‐carboxylate bridging complexes at mineral‐bitumen interfaces.
Kinetics of the catalytic hydrogenation of 2‐Ethyl‐2‐Hexenal
Authors: Collins Dermot J. , Grimes David E. , Davis Burtron H. 
Published: March 2009

Abstract2‐Ethyl‐2‐hexenal was hydrogenated over Raney Nickel and nickel boride in a batch slurry reactor. Using Raney Nickel, the reaction went to completion, and the formation of both 2‐ethylhexanal and 2‐ethylhexanol followed zero order kinetics.Using nickel boride, the reaction ceased at the saturated aldehyde, with saturation of the double bond a zero order reaction. Unsaturated alcohol was not detected in any of the reaction mixtures.
Adsorption/desorption models: How useful for predicting reaction rates under cyclic operation
Authors: Jain Anil K. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractA computational study is reported of the behaviour of three catalytic reaction models containing conventional adsorption, desorption, and surface reaction steps under conditions of forced composition cycling in a mixed reactor. The models contained varying degrees of non‐linearity. With long cycle periods, the time‐average rate of reaction asymptotically approached the quasi‐steady state. Time‐average rate behaviour was found to be bounded by the asymptotes of quasi‐steady state rate under slow cycling, and the relaxed steady state under rapid cycling. It is concluded that the approach used until now to model catalytic reactions is very likely inadequate to describe the dynamics of forced cyclic operation observed in a number of experimental systems
Laminar dispersion in helically coiled tubes of square cross‐section
Authors: Saxena Alok K. , Nigam K. D. P. 
Published: March 2009

AbstractIn coiled tubes of non‐circular cross‐section the orientation of the cross‐sectional plane with respect to the direction of the centrifugal force has a significant effect on residence time distribution (RTD) which has been recognized for the first time. This aspect has been experimentally investigated in helically coiled tubes of square cross‐section, under the conditions of negligible and significant molecular diffusion.
Surface diffusion as rate determining step in activated chemisorption
Authors: Birnholtz Hella , Nir Avinoam , Lotan Noah , Aharoni Chaim 
Published: March 2009

AbstractIt is assumed that heterogeneous surfaces contain regions with various activation energies for adsorption. Adsorbate is taken up at regions of low activation energy and it migrates subsequently to regions of higher energy by surface diffusion. Surface diffusion is activated and it determines the rate of the overall adsorption process. Expressions derived on the basis of this model are consistent with Aharoni–Ungarish (1976) rule concerning the kinetics of chemisorption, viz the plot of the reciprocal of the rate against the time is sigmoid and the kinetics obey successively the Bangham Equation, the Elovich equation, and a first order equation.
Gasification of peat in a steam plasma reactor
Authors: De Matons P. Grosdidier , Gauvin W. H. 
Published: March 2009

AbstractThe gasification of finely‐divided peat (30‐micron and 48‐micron sizes respectively, and 11.4% moisture) was studied in a reactor 30.5‐cm ID and 178‐cm high, in the presence of a plasma flame consisting of nitrogen and steam, at an initial temperature of 4000 K, decreasing to 1200 K in the reaction zone. For a carbon‐to‐steam molar ratio of 1.37, a conversion of 81% of the carbon was achieved, yielding a gas analyzing 43% H2, 44% CO, 8% CO2, 4% CH4 and 1% C2H6, with a calorific value of 266 kJ/g mol (319 Btu/ft3). The results indicated that higher temperatures and a lower C/H2O ratio were required to achieve near total carbon conversion.
Spray cone angle and its correlation in a high pressure fuel spray
Authors: Varde K. S. 
Published: March 2009

AbstractAn experimental study was conducted to determine the effects of nozzle orifice size and operating parameters on the cone angle of a liquid fuel spray injected into a gaseous environment. High fuel pressures in the range 55 to 130 MPa and background gas density ranging from atmospheric to 40 kg/m3 were used in the study. The results show the spray cone angle to depend on the orifice dimensions as well as on the operating conditions such as the injection velocity and the background gas density. A correlation is derived to predict spray cone angles in terms of Reynolds and Weber numbers. The predicted results are shown to agree well with the experimental findings of other investigators.
An axisymmetric model of flow in the annulus of a spouted bed of coarse particles. Model, experimental verification and residence time distribution
Authors: Littman Howard , Morgan Morris H. , Narayanan Pallassana V. , Kim Seung Jai , Day Jenn‐Yuan , Lazarek G. M. 
Published: March 2009

AbstractAn axisymmetric model of flow in the annulus of a spouted bed of coarse particles which takes into account non‐Darcy flow and utilizes a new and general axial pressure boundary condition at the spout‐annulus interface is presented. The pressure boundary condition and the annulus pressure distribution are experimentally verified and the model used to calculate the residence time distribution and the flowrate at the top of the annulus. In addition, the average axial velocity profile in the annulus is calculated and compared with predictions of several one‐dimensional flow models.
Liquid phase axial mixing in a bubble column with viscous non‐newtonian liquids
Authors: Devine W. D. , Shah Y. T. , Morsi B. I. 
Published: March 2009

AbstractThis paper presents some new data for the liquid phase axial dispersion coefficient in a bubble column with highly viscous non‐Newtonian liquids (μL > 0.03 Pa · s). The data were obtained in a 0.15 m diameter column operating in the slug flow regime, and the dispersion measurements were conducted using heat aas a tracer. The experimental results show that the dispersion coefficients increase with both gas and liquid velocities and quantitatively they are about three times higher than those obtained for the air‐water system. The results are explained based on a known hydrodynamic model of vertical gas‐liquid slug flow.
Liquid diffusion measurement by holographic interferometry
Authors: Ruiz‐Bevia F. , Fernandez‐Sempere J. , Celdran‐Mallol A. , Santos‐Garcia C. 
Published: March 2009

AbstractThe use of classic interferometry to study liquid diffusion has been well known since the 1940's. Much more recently holographic interfereometry was introduced in this field of study. In this paper a description of the general characteristics of holographic interferometry is presented. The evolution as well as the improvements of the technique are describged.
Vapor pressures of heavy liquid hydrocarbons containing nitrogen or sulfur
Authors: Chandar S. C. R. , Singh R. P. 
Published: March 2009

AbstractThe extended SWAP (Smith‐Winnick‐Abrams‐Prausnitz) correlation for vapor pressure has been applied in the region 1300‐266,000 Pa to a large number of hydrocarbon derivatives containing either nitrogen or sulffur as heteroatoms. With a minimum of experimental information including approximate characterization of molecular structure and one vapor pressure datum, vapor pressures can be estimated within ± 10%.
Experiments with concentrated slurries of particles with densities near that of the carrier fluid
Authors: Shook C. A. 
Published: March 2009

AbstractExperimental investigations of headlosses and particle velocity distributions have been undertaken for water slurries of polystyrene particles of diameter d50 = 0.3 and 1.4 mm. At concentrations greater than 40–45% by volume, nearly linear headloss vs. velocity relationships were obtained. These suggested laminar flow but the particle velocity measurements showed the flow to be turbulent.The results have been interpreted with an approximate theory based upon lubrication mechanics. The investigation illustrates the limitations of slurry viscometry in predicting pipeline behaviour for slurries of particles of this size.
The effect of temperature and moisture on the rheology of black coal‐oil suspensions
Authors: Ghosh Ajit K. , Bhattacharya S. N. 
Published: March 2009

AbstractRheological properties of black coal‐KC220 oil suspensions have been investigated using a Contraves rheometer over a temperature and coal volume fraction range of 18–200°C and 0.247‐0.385, respectively. The suspensions behaved as Newtonian fluids. Variation of viscosity with temperature does not follow any regular trend and peak viscosity values occur in the temperature range of 80–140°C for dry coal and 70–130°C for moist coal, depending upon the concentrations of coal in the suspension. Freshly prepared suspensions of moist coal exhibit viscosity peaks at a temperature lower than that of the corresponding suspension with dry coal. However, when aged, the suspensions of moist coal exhibit very small peak viscosity and follow an Arrhenius type behavior. For both dry and moist coal, the maximum volume fraction, ϕm, continues to decrease with an increase in temperature.
Laboratory study of solvent enhanced communication in oil sands
Authors: Isaacs E. E. , Green K. 
Published: March 2009

AbstractMiscible displacement experiments were carried out to evaluate the potential of solvents in enlarging fractures between wells to allow for larger volumes of steam to be injected during in situ recovery operations in the Athabasca oil sands deposit. The solvents tested included carbon disulfide, toluene and a series of refinery streams and diesel oils. Since incomplete miscibility between bitumen and some solvents caused asphaltenes to precipitate, solvents were ranked in terms of bitumen compatibility.Solvents such as diesel DP‐40 and diesel DC‐40, which are intermediate in terms of solubilizing bitumen, were the most efficient in developing zones of low bitumen saturation around an initial fracture and at the same time not extracting bitumen from other regions of the bed. The effects of flow rate and cell orientation on solvent efficiency and permeability are also described. Solvent losses corresponded to about the residual saturation of oil after waterflooding.
Phoretic phenomena in tar vapor‐particulate mixture separation from fuel gas streams
Authors: Vasudevan T. V. , Gokhale A. J. , Mahalingam R. 
Published: March 2009

AbstractAnalytical models were developed to predict the performance of a spray scrubber for separation of tars from gasifier off‐gas streams. The models included heat transfer, mass transfer, condensation, nucleation, temperature and flow fields, and various phoretic phenomena involved in droplet‐particle and droplet‐vapor interaction and collection. The models indicate that for the tar particulates, both Brownian diffusion and inertial impaction, rather than diffusiophoresis and thermophoresis, are the more important phoretic forces causing the collection. For the limiting case of all tars being present only as vapor, the efficiency of their removal by condensation on water spray droplets could be extremely high.Scrubbing experiments were carried out on the hot gas/tar stream evolved from the simulated devolatilization section of a laboratory fixed bed gasifier. The combined overall collection efficiency for a mixed particulates and vapor stream compares satisfactorily with the model predictions.
Biodegradation of organic compounds in fluidized bed reactors
Authors: Wong Shu‐Lun Simon , Tien Chi 
Published: March 2009

AbstractBiodegradation of organics in fluidized bed reactors was studied experimentally. Both single‐substrate and mixed‐substrate systems were considered. With the use of a previously developed biofilm model, parameters pertinent to the degradation of mixed‐substrate systems and their single substrate system counterparts were evaluated and compared.Two approaches attempted to predict the degradation of a mixed‐substrate system. One assumed independent biodegradaion and diffusion of individual substrates while the other used a lumped concentration approach. The latter approach was found to give better agreement with experiments than the former.
Influence of forced feed composition cycling on catalytic methanol synthesis
Authors: Nappi A. , Fabbricino L. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractStudies have been carried out between 230 and 270°C and 1.97 and 2.93 MPa total pressure on the synthesis of methanol over an industrial catalyst of the copper‐zinc oxide‐alumina type using a gradientless reactor. Two modes of forced feed composition cycling were explored: periodic variations of the mole fraction of H2 and CO and periodic variation of the CO2 content. The latter mode substantially improved methanol production and suppressed the parasitic formation of methane, while the former mode had just the opposite effect. Measurements of methanol, methane and CO during a cycle as well as separate observations of the response to step‐changes in concentration indicated substantial storage of CO on the catalyst surface. Rapid response of methane to the CO2 content suggests over‐reduced areas of the catalyst surface are responsible for methane formation and that these regions are readily oxidized. CO2 or H2O associated with methane formation appear to relate to the dynamics of methanol formation.
Comparison of the sulfation rates of calcium, magnesium and zinc oxides with SO2 and SO3
Authors: Kocaefe D. , Karman D. , Steward F. R. 
Published: March 2009

AbstractThe sulfation rates of reagent grade calcium and zinc oxides and technical grade magnesium oxide with sulfur trioxide and sulfur dioxide ‐ oxygen mixtures have been measured thermogravimetrically.Experiments have been conducted to determine the rate of reaction for various particle radii (0.071‐0.151 mm), temperatures (450‐1100 K.) and concentrations of sulfur dioxide, sulfur trioxide (0.075‐0.62 moles/m3), oxygen (0‐1.5 moles/m3).Experimental results are presented which compare the sulfation rates of each basic oxide with sulfur dioxide and sulfur trioxide at different temperatures. The rate of sulfation of different oxides are compared under the same experimental conditions.
Simple calculation technique to solve the leung/wiles equations for the choking load of multisize particles in pneumatic transport lines
Authors: Briens C. L. , Bergougnou M. A. 
Published: March 2009

AbstractLeung and Wiles (1976) proposed a quantitative procedure to calculate the maximum flowrate or “choking load” of solids which can be conveyed by a gas flowing at a given velocity in a vertical pneumatic transport line. However, no simple way of solving their equations was given by them. A new calculation method is proposed here to solve their equations to obtain the choking load of multisize particles.
Discharge composition and concentration profiles in a continuously operating spouted bed
Authors: Rovero Giorgio , Piccinini Norberto 
Published: March 2009

AbstractThe cause of segregation at the discharge in a continuously operating spouted bed has been investigated. Radial concentration profiles of the coarse component have been detected in a two‐component mixture of glass ballotini at different spouting regimes, at different bed levels and discharging from openings at several bed depths. The annulus of a spouted bed has been shown to move in a fashion close to a plug flow without altering the concentration gradients existing below the bed free surface. Consistent with previous results, percolation induced segregation was negligible under these experimental conditions. The concentration existing at the column wall has been shown to be identical to that in the outgoing stream of solids and segregation phenomena at the outlet cannot explain a discharge composition different from the mean concentration in the bed. The particle trajectories in the fountain are believed to be responsible for the radial concentration gradient in the annulus of the spouted bed.
Flow behaviour of oil‐in‐water emulsions
Authors: Pal R. , Bhattacharya S. N. , Rhodes E. 
Published: March 2009

AbstractThe rheological behaviour of concentrated oil‐in‐water emulsions has been investigated using the Weissenberg Rheogoniometer. The oil concentration has been varied from 40 to 95 volume percent. The effects of shear rate and oil concentration on the viscosity have been determined. From the rheological data, the maximum attainable oil concentration in the emulsion has been estimated and is introduced as a parameter in the relationship between relative viscosity and oil concentration to account for certain variations in the emulsion characteristics. Empirical equations have been obtained which correlate zero shear rate viscosity and infinite shear viscosity as a function of reduced oil concentration. Comparison has been made between the emulsion viscosity and the solid‐liquid suspension viscosity at high dispersed phase concentration. Estimated maximum attainable oil concentration is found to be in close agreement with the actual maximum concentration that could be achieved experimentally.
Discharge characteristics of orifice meters in sediment‐laden flows
Authors: Kapoor B. S. , Garde R. J. , Ranga Raju K. G. 
Published: March 2009

AbstractExperimental results on the discharge characteristics of concentric orifice meters placed in circular pipes carrying sediment‐laden flow in homogeneous and heterogeneous regimes are reported. The experiments were carried out using water as the carrying medium and sand and coal as the sediments. The data cover a range of concentration from 0.5% to 7.0% by volume. The analysis of the data has resulted in graphical predictors which enable determination of the discharge to fairly good accuracy.
Gas—liquid pressure drop studies in a reciprocating plate column
Authors: Rama Rao N. V. , Baird M. H. I. 
Published: March 2009

AbstractTwo‐phase pressure drop in a 93 mm diameter reciprocating plate column (RPC) was studied for the air‐water system, and to a lesser extent for air‐kerosene. Amplitudes (strokes) in the range 14 to 63.5 mm and frequencies from 0.75 to 4.0 Hz were investigated for between 2 and 10 brass plates with hole diameters from 3 to 8 mm and free flow area between 0.09 and 0.306. Continuous phase velocity was varied from 1.24 to 3.72 cm s−1 and dispersed phase velocity varied from 0.04 to 5.10 cm s−1. The measured pressure head was subjected to a static head correction based on the measured holdup of the dispersed phase and densities of the phases. The data were correlated by regression analysis as a friction factor expressed in terms of loading ratio, Reynolds number and Froude number; they were also compared with an earlier theoretical prediction by Noh and Baird for single phase flow in a RPC. The two‐phase pressure drop was found to increase with agitation both in the mixer‐settler and emulsion regions and reached a maximum at vibrating speeds around 10 cm s−1. Beyond this point, it decreased in the unstable region preceding flooding. It was concluded that the RPC could be effectively used in the emulsion region for optimum performance.
Kinetics of oil extraction from canola (rapeseed)
Authors: So George C. , Macdonald Douglas G. 
Published: March 2009

AbstractThe extraction of oil from canola (rapeseed) using hexane as a solvent can be described by a two stage washing/diffusion model. Oil which is at the surface of the seed as a result of pressing or cooking is removed rapidly at the beginning of the extraction process by simple washing by the solvent. This is followed by a slow extraction of the oil from the seed by a diffusional process. This latter process appears to be controlled by two mechanisms: slow, unhindered diffusion of oil held in the ruptured cells in the seed; and very slow, hindered diffusion of oil held within unruptured cells in the seed. To evaluate this model, rapeseed was extracted with commercial hexane in a simple bench scale batch extractor and the effects of variables such as particle thickness, temperature, cooking, degree of agitation, and solvent‐to‐seed ratio were studied.
Model for continuous drying of solids in fluidized/spouted beds
Authors: Viswanathan K. 
Published: March 2009

AbstractA mathematical model is presented for predicting the dynamics of continuous drying of solids in fluidized and spouted beds (start‐up period). The outlet solids moisture content \documentclass[article]\pagestyle[empty]\begin[document]$ \bar Q $ \end[document], the outlet humidity and the solids temperature are predicted as a function of time for both falling (internal diffusion controlled) and constant rate drying periods. It is shown that the initial moisture content of the solids in the bed, Qd, is a critical variable. Three characteristic types of dynamic behaviour are identified depending upon the value of Qd. For falling rate, a large Qd results in unacceptably high \documentclass[article]\pagestyle[empty]\begin[document]$ \bar Q $ \end[document] in the initial periods whereas a small Qd results in excessive temperature rise which may cause damage to solids. For constant rate, the responses of outlet humidity and solids temperature are independent of Qd. Analytical expressions are derived for the time required to reach steady state, the solids moisture content, and temperature at steady state. The model should also be useful for control of dryers.
Absorber simulation and design using a nonequilibrium stage model
Authors: Krishnamurthy R. , Taylor R. 
Published: March 2009

AbstractA nonequilibrium stage model of multicomponent separation processes is used to simulate three representative nonisothermal gas absorption processes: (i) the absorption of ammonia from air using water, (ii) the purification of an acid gas stream using cold methanol and (iii) a process in which a heavy hydrocarbon oil is used to absorb a mixture of lighter hydrocarbons. The temperature profiles and terminal stream compositions predicted by the model compare well with experimental measurements on the ammonia/air/water and acid gas/methanol systems. The case study involving the absorption of light hydrocarbons is used to demonstrate that there can be large differences between designs based on the nonequilibrium stage model and the efficiency‐modified‐equilibrium‐stage model.