bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of partial poisoning of acid sites on selectivity in the multiple reactions of mono‐substituted‐t‐Butylbenzenes
Authors: Takahashi Takeshige , Kuramoto Kenji , Kai Takami , Tashiro Masashi
Published: March 2009

The decomposition reaction of p–t‐butylcumene and t‐butylbromobenzene have been carried out over pyridine poisoned silica‐alumina and HY zeolite in order to examine the effect of acid strength on selectivity.

Since the catalyst deactivation rate for isomerization over the poisoned silica‐alumina was greater than that of de‐t‐butylation in the reaction of p–t‐butylcumene, the selectivity of de‐t‐butylation gradually improved with process time.

In the reaction of t‐butylbromobenzene over poisoned HY zeolite, the de‐bromination rate was suppressed by the poisoning because the nature of active sites was different between silica‐alumina and HY zeolite. The poisoned HY zeolite was found to be favorable for the de‐t‐butylation of halogenated‐t‐butylbenzenes.
Thermodynamic aspects of the utilization of coal‐based raw materials within the system of the petrochemical industry
Authors: Sokić Milorad , Cvetković Ružica , Trifunović Zoran
Published: March 2009

The system of processes for producing olefins and aromatics was investigated in order to assess the thermodynamic aspects of the substitution of actual petrochemical raw materials by coal.

As coal conversion technologies offer several alternative processing routes for the production of olefins and aromatics, a mathematical model of the system was used to generate the optimum, as well as suboptimum system structures, with respect to the objective of efficient energy utilization, expressed as the minimum total lost work rate.

The relative importance of direct, as well as indirect, coal liquefaction processes was discussed considering both raw materials and energy utilization efficiency.
Zinc electrowinning with 2‐butyne‐1,4‐diol
Authors: Piron D. L. , Mathieu D. , D'Amboise M.
Published: March 2009

The beneficial effect of 2‐butyne‐1,4‐diol on zinc current efficiency in the presence of nickel impurity has been examined. Several techniques including HPLC, absorption spectrophotometry and constant current deposition experiments have shown that a trimer of 2‐butyne‐1,4‐diol is responsible for the removal of Ni ions from the electrolyte, thus increasing the current efficiency of the zinc electrowinning process from sulphate solutions (60 g/L Zn + 200 g/L H2SO4) in the presence of Ni ions.
Gas‐liquid mass transfer in “dead‐end” autoclave reactors
Authors: Chaudhari R. V. , Gholap R. V. , Emig G. , Hofmann H.
Published: March 2009

Gas‐liquid volumetric mass transfer coefficients, (kLa), have been obtained for “dead‐end” autoclave reactors operated in two different modes: (a) gas introduced into the gas phase, and (b) gas introduced through a dip‐tube in the liquid. Three different methods of kLa determination have been compared. Effects of agitation speed, impeller diameter, gas to liquid volume ratio (Vg/VL), position of the impeller and reactor size on kLa have been investigated. The kLa data were found to be correlated as:

kLa = 1.48 × 10−3 (N)2.18 (Vg/VL)1.88 (dI/dT)2.16 (h1/h2)1.16

The critical speed of surface breakage, at which transition from the surface convection to the surface entrainment regime occurs, was also determined for different impeller positions, impeller diameters and gas to liquid volume ratios.
Axial dispersion, holdup and flooding characteristics in pulsed extraction columns
Authors: Yu Yong‐Ho , Kim S. D.
Published: March 2009

The effects of interactions between the perforated and baffle plates, of pulse amplitude and of pulse frequency on axial dispersion in the continuous phase, on the dispersed phase holdup and on the flooding condition have been determined for a 10.2 cm 1D pulsed extraction column. The axial dispersion coefficient increased with both the pulse amplitude and the frequency, but it decreased with the decrease in baffle spacing in the unit module. Dispersed phase holdup increased with the number of perforated plates in the unit module at the lower pulsation velocities and increased with the pulse velocity. The baffle plate reduced the total throughputs, but baffle spacing did not have any significant effect on the total throughput.
Oxygen‐steam gasification of coals in a spouted bed
Authors: Watkinson A. P. , Cheng G. , Lim C. J.
Published: March 2009

A bituminous and a sub‐bituminous coal from Western Canada have been gasified in oxygen‐steam and air‐steam mixtures in a 0.30‐m diameter, 50 kg coal/h continuous spouted bed reactor. Results are presented to show the effects of the blast composition and reactor temperature on gas heating value and carbon conversion. Operation in the ash agglomeration mode is illustrated, and the role of K2CO3 as catalyst explored. Results from a wide range of experimental gasification conditions are compared with predictions of an equilibrium model.
Application of orthogonal collocations to some transport phenomena problems in co‐axial cylinders and spheres
Authors: Goyal S. K. , Esmail M. N. , Bakhshi N. N.
Published: March 2009

Collocation methods are developed for the solution of some differential equation models for transport phenomena problems in one‐and two‐dimensions in co‐axial annuli of spherical and cylindrical shapes. General formulae are developed to obtain orthogonal polynomials over an arbitrary interval using two types of weighting functions. The convergence and accuracy of the methods are demonstrated using two test problems, i.e., calculation of effectiveness factors in (a) a spherical pellet with peripherally deposited catalyst and (b) a Raschig ring type cylindrical catalyst pellet. Comparisons of results obtained from the present methods with analytic solutions for the first‐order reactions indicate good agreement. Numerical solutions are also obtained for the second‐and the third‐order reactions for which analytic solutions are not available. Results obtained in terms of a new Thiele modulus involving the ratio of volume of peripherally deposited part of catalyst to exterior surface area indicate that this normalization brings effectiveness factor versus Thiele modulus curves close together for co‐axial spherical and long cylindrical pellets, as it does for these geometries without the inner co‐axial portion.
Modélisation et simulation de la décomposition catalytique du méthanol dans un réacteur à lit fixe
Authors: Thérien Normand , Tessier Patrick
Published: March 2009

Un modèle à paramètres distribués représentant le comportement dynamique d'un réacteur tubulaire catalytique dans lequel a lieu une réaction endothermique de décomposition du méthanol en hydrogène est présenté. Les prévisions obtenues tant au niveau thermique qu'au niveau cinétique, en régime permanent et en régime transitoire ont été comparées à des résultats expérimentaux et montrent l'aptitude du modèle à reproduire les comportements du réacteur étudié. Une étude de sensitivité a permis de montrer l'importance de certains paramètres du modèle sur les résultats.
The fischer—tropsch synthesis over a ruthenium catalyst under composition cycling
Authors: Ross Gerald S. , Hudgins R. R. , Silveston P. L.
Published: March 2009

The influence of feed composition cycling on the activity and selectivity of the Fischer‐Tropsch synthesis over an alumina‐supported ruthenium catalyst was investigated using a fixed‐bed reactor at 211°C and 446 kPa total pressure. Forced composition cycling suppressed the overall synthesis rate but increased the rates of formation of the C1 to C4 paraffins and shifted the paraffin/olefin ratio.
An analysis of simultaneous absorption of two gases reacting between themselves in a semi‐batch reactor
Authors: Bhattacharya A. , Chaudhari R. V.
Published: March 2009

The problem of simultaneous absorption of two gases reacting between themselves in a semi‐batch reactor has been analysed. An exact analytical solution for the enhancement factor has been obtained which requires neither a prior knowledge of the regime of absorption nor arbitrary choice of bulk liquid phase concentrations of gaseous reactants. The methodology developed here can easily be extended to a continuous flow reactor.
Distinctive burning characteristics of carbon particles
Authors: Annamalaim K. , Caton J. A.
Published: March 2009

Several reaction mechanisms exist in the literature for the gasification of char/carbon particles. The general procedure for modelling particle gasification is to assume a mechanism of combustion, obtain the theoretical burning rate and particle temperature, and then validate the mechanism by comparing the results with experimental data. The present work shows that the burning rate and particle temperature are independent of heterogeneous and homogeneous reaction mechanisms and their rate kinetics as long as the oxygen (O2) and carbon dioxide (CO2) concentrations at the burning surface are low compared to carbon monoxide (CO) concentration. Experimental data are cited which are in agreement with the model's predictions for both particle temperatures and burning times. The relevance of the results to industrial combustors is discussed.
Frictional loss in multiplate bubble columns
Authors: Chen B. H. , Wakao N.
Published: March 2009

Gas holdup and pressure loss were measured for various gas‐liquid systems in a batch, multistage bubble column. Experimental results show that the use of screen plates (α = 0.64) considerably increases the gas holdup but introduces a significant pressure loss for the two‐phase mixture. The pressure loss was found to be independent of physical properties of the mixture, and predictable either from the modified separated flow model (Chen et al., 1986) or from the kinetic energy loss based on the liquid circulation velocity.
Drop size distribution in a liquid‐liquid spray column via a photographic technique
Authors: Lin F. , Ford J. D.
Published: March 2009

A photographic technique was devised for obtaining drop size distribution in a liquid‐liquid (kerosene‐water) spray column. Drop sizes were determined with the aid of a reference ball, using a double‐flash technique with side lighting. Experimentally analyzed Sauter mean diameters were in good agreement with those predicted by the Kumar and Hartland correlations. The technique was applied up to a holdup of about 6% in this countercurrent flow study
Boundary element prediction of the free surface shape between two particle plugs in a horizontal pneumatic transport pipeline
Authors: Konrad K.
Published: March 2009

A method is presented to predict the shape of the gas‐particle interface between two plugs of cohesionless particles conveyed pneumatically through a horizontal pipeline. The method assumes that the moving solids are limiting equilibrium at the interface and that, therefore, the interfacial slope depends on the normal pressure gradient which can be used as a boundary condition for the numerical solution of Laplace's equation. The height of stationary material between the plugs cannot be predicted by the method, since this material is not in a state of limiting equilibrium. However, an analogy with a gas‐liquid system can be used to predict this height. The method as presented is restricted to plugs of constant voidage and to systems which obey Darcy's law (packed bed Reynolds numbers less than 10). The boundary element numerical technique is used to apply the method to a 2‐dimensional example of flow through a 50 mm I.D. pipe. The predictions are qualitatively in agreement with photographs of the observed shape in the true (3‐dimensional) situation. However, further numerical and experimental work on the 3‐D situation is required for a full assessment of the proposed method.
Mass transfer characteristics in a gas–liquid reciprocating plate column. II. Interfacial area
Authors: Veljković Vlada , Skala Dejan
Published: March 2009

This paper is the second part of a continuing study on mass transfer in a reciprocating plate column. The first part dealt with kLa. The bubble size distribution, the Sauter mean diameter and the interfacial area are the subject of this paper.

The bubble size increases slightly with gas flow rate and decreases with agitation intensity above a “critical” level. The interfacial area increases with increasing agitation and aeration intensities, while the liquid flow rate and coalescing properties of the liquid have no significant effect. The specific interfacial area is correlated in terms of the superficial gas velocity and the maximum power consumption.

The correlations obtained for kLa and a were used to calculate kL. It was found that kL depends on the agitation intensity and the bubble size.
Gas filtration in granular moving beds — an experimental study
Authors: Tsubaki J. , Tien Chi
Published: March 2009

An experimental study was conducted of gas filtration in cross‐flow moving‐bed granular filters. Variables examined included both the gas and solid velocities as well as filter‐grain size. The triboelectric effect was found to play an important role in determining the extent of particle collection.
A finite element model of the ventilation pattern inside an industrial building: Non‐isothermal case
Authors: Tanguy P. A. , Dupuis M.
Published: March 2009

A finite element investigation of the ventilation conditions in a heated building in which the flow is characterized by the existence of a strong effect of natural convection at high Grashof number is presented. The computation of the velocity and the temperature pattern is performed in an intertwined manner, the coupling being performed by a time stepping technique. The proposed solution strategy allows computations at a very reasonable cost. Numerical predictions are compared to experimental data, and exhibit a very good agreement for the velocity field and a fairly good agreement for the temperature.
Heat transfer modelling of sieve trays
Authors: Spagnolo D. A. , Plaice E. L. , Neuburg H. J. , Chuang K. T.
Published: March 2009

A heat transfer model that accounts for both gas and liquid phase resistance was developed for sieve trays where the overall heat transfer coefficient is expressed as a function of Sauter‐mean bubble diameter. These diameters, obtained from pilot plant data, were correlated and used to predict point efficiencies on production plant trays. Applying the appropriate liquid flow distribution model allows the prediction of overall tray efficiencies. Predicted temperature profiles have agreed well with measured plant profiles and tray changes at the production plant have resulted in steam savings that were adequately predicted by the model.
Flotation kinetics for titanium, zirconium and bitumen recovery from oilsand tailings
Authors: Ityokumbul M. T. , Bulani W. , Kosaric N.
Published: March 2009

The kinetics of heavy mineral and bitumen recovery from oilsand tailings are presented. The results show that the recovery rates for titanium, zirconium and bitumen were affected by addition of surfactants Tretolite F46 and E3453. Recoveries were a function of time and of the minerals and bitumen present.
Kinetics of reactions involved in pyrolysis of cellulose I. The three reaction model
Authors: Agrawal Ravindra K.
Published: March 2009

Kinetics of reactions involved in pyrolysis of cellulose has been modeled in terms of a three reaction model. In this model it is assumed that cellulose decomposes to tars, chars and gaseous products via three competitive first‐order reactions. Arrhenius parameters have been obtained to describe the rate constants of these reactions. The three reaction model predicts the weight loss data reasonably well. Product yields of tars, chars and gases predicted by the three reaction model are compared over the temperature range 250 to 360°C. In this communication a technique for analyzing experimental data of a solid state reaction is presented.
Heats of mixing of amine/alkane and amine/alcohol systems at 288.15 and 308.15 K. Correlation and prediction with AGSM and with the quasi‐chemical theory
Authors: Chamblain J. F. , Vera J. H.
Published: March 2009

Experimental heats of mixing data for n‐amylamine with n‐heptane and n‐nonane and with 1‐hexanol, 1‐octanol and 1‐decanol at 288.15 and 308.15 K are reported. The data were obtained using a semicontinuous isothermal dilution Van Ness type calorimeter. Experimental data from this work along with the data from other sources were used to test the predictive potential of the Analytical Group Solution Model (AGSM) and of the Quasi‐Chemical theory.
Adsorption of 1‐Butanethiol from kerosene oil on red mud
Authors: Singh A. P. , Singh P. C. , Panday K. K. , Singh V. N.
Published: March 2009

Adsorption studies indicate that low concentration and high temperature favour the removal of 1‐butanethiol from kerosene oil by adsorption on red mud. A first order mechanism has been proposed to describe the adsorption in the present system. Equilibrium data at different temperatures fit well in the Langmuir isotherm equation. Thermodynamic parameters for the present system indicate the feasibility of removal of 1‐butanethiol from kerosene oil by adsorption on red mud.
Gamma‐Ray method for measuring liquid expansion coefficient at high temperatures and pressures
Authors: Liu D. D. S. , Patmore D. J. , Yuyitung T. S. , Lipsett J. J. , Chapman K.
Published: March 2009

Expandable vessels were designed to measure the density and thermal expansion coefficients of liquid at elevated temperatures and pressures by the gamma‐ray attenuation method. Light Arabian vacuum bottoms was tested from 70°C to 300°C at 13.8 MPa. Results agree well with literature data.
Generalized solutions for a dead‐end duct having a permeable barrier
Authors: Ryan J.T. , Griffin Wayne H.
Published: March 2009

This paper presents an analytical method for calculating the flow and pressure in A dead‐end duct which has a perforated, porous barrier and an auxiliary fan or an obstacle at the end of the duct. The solutions involve two infinite series which can be applied to a general class of differential equations. It is shown that the duct length may be bounded if the barrier is porous only. No such bound exists if there are holes in the barrier. There is a minimum in the flowrate through the duct when there is a fan at the dead end. No such minimum exists when there is an obstacle
The kinetics of the oxidation of propylene over a bismuth molybdate catalyst
Authors: Tan H. S. , Downie J. , Bacon D. W.
Published: March 2009

Using statistical design procedures an initial‐rate study of the oxidation of propylene over a silica‐supported bismuth molybdate catalyst was carried out using a differential‐bed reactor over the following range of conditions: temperatures from 350 to 390°C, oxygen and propylene concentrations from 1.0 to 8.0 mmol/L. Among the models considered a Redox Steady‐State Model (with half‐order oxygen concentration) involving oxygen adsorption and reaction with propylene from the gas phase was found to provide the best fit to the data.
The development of a mini‐plant chlorinator for ferric chloride leach processes
Authors: Tan K. G. , Bedard P. L.
Published: March 2009

A packed column reactor was designed and tested for the chlorination of ferrous chloride leach solutions in a co‐current contacting mode. The reaction is exothermic and gas film controlled, and the size of the reactor can be estimated using literature data. The target throughput of 1 L/min solution containing about 1 rnol FeCl2/L, 3 rnol NaCI/L, and 0.5 rnol HCI/L (plus some PbCl2, ZnCl2, and CaSO4) was adequately treated in a 5 cm diameter column packed to a height of 50 cm with 1 cm Raschig rings. Further process development work and kinetic measurements were conducted in smaller (2 cm) diameter columns. These investigations yielded reliable mass transfer data which are useful both for scale up purposes and for a fundamental understanding of the reactions involved.
Viscosity of n‐alcohol binary mixtures
Authors: Orts M. J. , Medina P. , Aucejo A. , Burguet M. C.
Published: March 2009

In this paper liquid mixture viscosities at 25 °C for 18 binary systems formed by primary n‐alcohols have been measured. These values were fitted to Topological Treatment of Mixtures (T.T.M.) The pure compound topological description is obtained following the DARC system rules. A weighting function was introduced to obtain the topological description of a mixture. The results obtained with this model agree with experimental data (average deviation less than 2% in all cases).
An improvement on the quraishi‐fahidy method of dimensional analysis
Authors: Chen J. J. J.
Published: March 2009

An improvement on the Quraishi‐Fahidy method of dimensional analysis is given which is based on the systematic use of basic matrix algebra. This allows the construction of dimensionless groups to be carried out on the computer using standard matrix algebra software, a procedure which would be most effective when the constitutive matrix is very large. While this is not generally the case with many physical systems, the method illustrates the direct application of matrix algebra to an engineering problem.
Flocculation of kaolin suspension with cationic polymer
Authors: Kage Hiroyuki , Matsuno Yoshizo , Higashitani Ko
Published: March 2009

Flocculation experiments have been carried out using cationic polymers and kaolin suspensions. The effects of polymer dosage, kaolin concentration, pH, agitation, molecular weight and charge density of polymer, concentration of polymer solution, and addition of inorganic salt were systematically examined. It was found that two optimal points of polymer dosage exist between 0 to 8 × 10−3 kg/kg‐kaolin. The flocs formed at each optimal dosage are different from each other in shape and in size. It is concluded that these two kinds of flocculation are respectively caused by the neutralization of the surface charge of the particles due to the adsorption of free polymer and by the incomplete neutralization owing to the presence of polymer droplets.
Pressure drop through multiorifice gas distributors in fluidized bed columns
Authors: Briens C. L. , Tyagi A. K. , Bergougnou M. A.
Published: March 2009

Good grid design is essential for the satisfactory performance of large gas fluidized beds and requires the accurate prediction of the grid pressure drop. Experiments conducted with various perforated plate distributors in a 0.6 m I.D. fluidized bed column showed that the presence of fluidized solids could increase the grid pressure drop by more than 100%. This increase was around 25% for a grid pressure drop to bed pressure drop ratio of 0.4. It was greatly affected by the bed height. An investigation of various possible causes for this increase demonstrated that it is primarily caused by the backflow of fluidized solids into the grid holes under the influence of waves at the bed surface.
Kinetics and selectivity of reactions of 1‐alkenes on HY zeolite: The influence of chain length
Authors: Abbot J. , Wojciechowski B. W.
Published: March 2009

Catalytic reactions of 1‐alkenes on HY have been studied at 400°C. Skeletal isomerization to the corresponding rnonornethylalkene is the dominant initial process. Cracking and coke formation are also observed as initial processes. Initial cracking selectivity can be accounted for by monomolecular β‐scission processes involving a carbenium ion intermediate. However, the initial cracking product distribution for l‐hexene must be explained by assuming some contribution from a dimerization‐cracking mechanism.

The kinetics of these processes have been fitted by a model previously used to describe the reactions of n‐alkanes. It is found that the rate constants for both skeletal isomerization and cracking increase with chain length of the feed alkene.
Coupled optimization and evaluation of phase equilibria and thermodynamic properties of the benzene‐cyclohexane system
Authors: Sangster J. , Talley P. K. , Bale C. W. , Pelton A. D.
Published: March 2009

An extensive review of reported vapour‐liquid equilibrium, solid‐liquid equilibrium, excess enthalpy, excess heat capacity and other phase equilibrium and thermodynamic data for the system benzene‐cyclohexane is presented. Selected phase equilibrium and thermodynamic data have been simultaneously optimized and fitted to a single polynomial series expression in composition and temperature for the excess Gibbs energy of the liquid. This expression has been used to evaluate all the diverse types of data known for this system. This single expression gives a self‐consistent description of all known data in the very wide temperature interval 232–500 K.
Axial dispersion models for displacement washing of packed beds of wood pulp fibres
Authors: Poirier N. A. , Douglas W. J. M. , Crotogino R. H.
Published: March 2009

Axial dispersion models were developed for displacement washing of black liquor from packed beds of wood pulp fibres using pure wash water. For high initial bed liquor concentrations, the simple axially dispersed plug flow model was satisfactory for describing the experimental displacement washing breakthrough curves. For low initial bed liquor concentrations, the model was modified by the addition of a source term to account for the release of adsorbed and absorbed solutes which are transferred from the fibres to the wash fluid, and which become significant at low concentrations. Equilibrium between the fibres and the surrounding liquor was assumed. The highest Peclet numbers corresponding to the highest displacement washing efficiencies were obtained at high bed heights and low bed consistencies, for any superficial velocity.
Modeling of naphtha pyrolysis in swaged coils
Authors: Parameswaran Ayalur K. , Sharma Vimal K. , Kunzru D.
Published: March 2009

Pyrolysis of naphtha in uniform diameter and swaged reactors has been modeled. Pyrolysis and coking models available for naphtha cracking were used to calculate the reactor profiles of pressure, process gas temperature, tube metal temperature, conversion and the product yields. For the swaged coil, not only was the inlet pressure and maximum tube wall temperature in the clean condition lower than for a uniform diameter reactor, but the increase in the inlet pressure and maximum tube wall temperature due to coke deposition was also less. Swaging the reactor can result in a significant increase in the run length between decokings.
The use of the simplex method to characterize dry cellulose acetate membranes for gas separations
Authors: Tremblay A.‐Y. , Fouda A. , Lui A. , Matsuura T. , Sourirajan S.
Published: March 2009

The normal and log‐normal distributions are used to describe the pore size distribution of dry asymmetric cellulose acetate membranes for CO2/CH4 separations. Various optimization techniques are implemented to determine the distribution parameters R and σ as well as the constants A1, and A2, related to pore structure and surface transport. respectively. By using the Simplex method, a unique solution for the characterization parameters is easily obtained irrespective of the starting search point. The permeation data of helium was used to characterize the membranes and determine the flow parameters which can be used to predict the performance of those membranes in separating CO2/CH4 mixtures.
Mass transfer in tube bundles with liquid fluidized particles
Authors: Nieva Isabel A. , Böhm Ursula
Published: March 2009

Experimental studies were conducted of overall and local tube‐to‐liquid mass transfer for bundles of horizontal tubes in staggered and in‐line arrays in a liquid fluidized bed. The mass transfer coefficients are compared with those obtained using a fixed packing and those obtained without particles at the shell‐side of the bundle.
Experimental study of dispersion in a consolidated sandstone
Authors: Kinzel Douglas L. , Hill Gordon A.
Published: March 2009

Dispersion experiments were conducted on a Berea sandstone core having a permeability of 0.28 (μm)2, using chloride ion as the water soluble tracer to provide quantitative information useful to the prediction of the motion of reservoir fluids in enhanced oil recovery. Both single phase (water only) and two phase (water plus oil) experiments were completed under identical operating conditions in order to observe flow differences. The theory of Ebach and White (1958) was used to determine the dispersion coefficients. It has been found that over a wide range of fluid velocities, low concentrations of oil have no effect on the dispersion of chloride ions in the water phase but high concentrations of oil (S0 ˜ 0.55) resulted in a dispersion coefficient 2.2 times higher than for chloride ions in water alone.

This work indicates that the presence of an immiscible phase has a pronounced affect on the dispersion coefficient in porous media and must be accounted for in quantitative modeling of reservoir flows.
Mass transfer and selectivity of ozone reactions
Authors: Mehta Y. M. , George C. E. , Kuo C. H.
Published: March 2009

The present research concerns the behavior of mass transport in absorption of ozone accompanied by decomposition and ozonation reactions in aqueous solutions. On the basis of the film theory, a mathematical model has been formulated for the transport process taking into account molecular diffusion and the simultaneous decomposition and ozonation reactions of different orders. Analytical approximate and finite difference methods have been employed to predict concentration profiles, enhancement factor and selectivity of the chemical mass transfer in gas‐liquid systems.

The rate of mass transfer is enhanced by the chemical reactions as well as the availability of liquid reactant in the aqueous phase. When the ozonation reaction is much faster than the decomposition reaction, a large fraction of the absorbed ozone is utilized effectively in reacting with the liquid constituent and a high selectivity of the gas‐liquid reactions can be obtained. Calculated results indicate that removal of certain organic pollutants by the oxidation process may be effective only in acidic or neutral solutions where a high mass transfer rate and selectivity is achieved.
Expansion behaviour of confined fluidized beds of fine particles
Authors: Donsì G. , Ferrari G. , Formisani B.
Published: March 2009

The expansion behaviour of fluidized beds of fine particles confined within packings of coarse spheres has been studied experimentally. An expansion law of the Richardson‐Zaki type has been demonstrated to be valid in a wide range of voidages for fine particles belonging to A as well as to B group of Geldart's classification. Parameters of the proposed correlation have been evaluated and their dependence on fines properties discussed.
The reaction network for the oxidation of propylene over a bismuth molybdate catalyst
Authors: Tan H. S. , Downie J. , Bacon D. W.
Published: March 2009

An initial‐rate study was conducted to determine the kinetics of the oxidation of acrolein over a bismuth molybdate catalyst. The results were combined with results from a previous initial‐rate study of propylene oxidation on the same catalyst to develop a quantitative description of the reaction network for propylene oxidation.

The redox steady‐state model with half‐order in oxygen which provided the best fit to the propylene oxidation data also provided the best fit to the acrolein oxidation data. The disappearance of propylene occurs through parallel reactions to acrolein, carbon oxides, and acetaldehyde, with subsequent oxidation of the acrolein to carbon oxides.
Pyrolysis of grain screenings in a batch reactor
Authors: Utioh Alphonsus C. , Bakhshi Narendra N. , Macdonald Douglas G.
Published: March 2009

A preliminary study of the pyrolysis of grain screenings (wheat) has been carried out using a batch pyrolysis unit operating at atmospheric pressure. Grain screenings are the materials removed mechanically from grains (wheat, rapeseed, barley, etc.) by cleaning or separating equipment in grain elevators. Reaction conditions were varied to determine the effect of these changes on the final product (tar, gas, and char). The reaction variables manipulated included temperature (600–800°C), nitrogen carrier gas velocity, and potassium carbonate catalyst. It was found that the yields of ethylene were higher than those of ethane. These hydrocarbons were accompanied by smaller but significant yields of hydrogen and C4 to C6 hydrocarbons. The grain screenings impregnated with 15 wt% potassium carbonate catalyst gave higher synthesis gas yields with a H2/CO mole ratio up to 4.1. With the experimental set up used in the present study, the mass balances achieved were low and ranged between 65 and 77% of the weight of the grain screenings used.
Gibbs energy of mixing from empirical models
Authors: Peng Ding‐Yu
Published: March 2009

The Gibbs energy of mixing loci for selected nonideal binary systems at low pressures have been calculated using the gamma‐phi approach. It is shown that, in order to yield correct results which are consistent with both the Gibbs energies for the pure components and the theory of representing the coexisting phases by a simultaneous tangent line, the fugacities of the pure components must be properly defined. Each of the Gibbs energy of mixing loci so calculated consists of two distinct curves for the homogeneous vapor and liquid phases and the simultaneous tangent line(s) for the heterogeneous region(s).
Mathematical model for gas flow through a packed bed in the presence of sources and sinks
Authors: Osinski E. J. , Barr P. V. , Brimacombe J. K.
Published: March 2009

Flow within a packed bed is normally calculated by attempting to simultaneously satisfy the continuity and Ergun equations. However, the presence of gas sources/sinks within the bed escalates the complexity of the problem, particularly when the flow is two‐dimensional and a solution to the full Ergun equation is required. In quest of an efficient and dependable algorithm for the calculation of gas flow, a critical review of existing solution methods was undertaken and a new method, ‘FLOW’, is now proposed. The technique retains the viscous and inertial pressure gradient terms of the Ergun equation, and both are treated as linear functions of the flow. Solutions are approached iteratively; using finite difference techniques, the continuity and linearized Ergun equations are solved for the pressure field; a new flow field is then calculated from which is derived an adjustment to the inertial resistance term of the Ergun equation. The sequence is repeated until satisfactory convergence is obtained. Relatively few iterations are normally required and, for the case of negligible inertial pressure drop, one calculation cycle is sufficient. A comparison of results obtained using the ‘FLOW’, modified ‘SIMPLE’ and vorticity procedures is presented. The proposed method allow flexibility in the specification of boundary conditions and can be applied to compressible or incompressible flow, as well as for the case of nonisothermal beds.
Experimental study of the elutriation of particles from rotary kilns
Authors: Tackie E. N. , Watkinson A. P. , Brimacombe J. K.
Published: March 2009

The elutriation rate of fine solids from a rotary cylinder was studied as a function of air flowrate, rotational speed, percentage of solids fill, wall roughness and fine solids fraction. Local fines concentrations measured in the gas phase showed that solids travelled predominantly in saltation within 2 cm of the bed surface. The elutriation rate was influenced by cylinder exit dam geometry, wall roughness and segregation patterns in the bed. Gas velocity showed a very strong effect, with elutriation rate varying with velocity to a power of 4.6. An entrainment mechanism has been formulated based primarily on the collision of saltating particles on the solids bed.
Assessment of control loop performance
Authors: Harris Thomas J.
Published: March 2009

For processes described by linear transfer functions with additive disturbances, the best possible control in the mean square sense is realized when a minimum variance controller is implemented. It is shown that an estimate of the best possible control can be obtained by fitting a univariate time series to process data collected under routine control. No ‘identifiabüity’ constraints need be imposed. The use of this technique is demonstrated with pilot plant and production data.
Flow characterization of a flotation column
Authors: Pal Rajinder , Masliyah Jacob
Published: March 2009

The flow characteristics of a froth flotation column have been experimentally studied using air and aqueous surfactant solutions without the presence of solids. The hold‐up behaviours of the bubbly and the froth zones of the column were linked together using the drift‐flux model. The ratio of the gas drift‐flux, jgf, to the bubble terminal velocity, V, for both the bubbly and the froth zones was found to be well correlated by the Richardson–Zaki equation:
Phase equilibrium in the system water‐hydrogen sulphide: Modelling the phase behavior with an equation of state
Authors: Carroll John J. , Mather Alan E.
Published: March 2009

In the light of the information presented by Carroll and Mather (1989), a new interpretation is presented for the often‐quoted, smoothed data of Selleck, Carmichael and Sage (1952) for the phase equilibrium in the system water‐hydrogen sulphide. The data of Carroll and Mather show that the liquid‐liquid‐vapour locus extends to higher temperatures than believed by Selleck et al. Experimental data from several sources are correlated using the Stryjek‐Vera (1986a) modification of the Peng‐Robinson (1976) equation of state. It is demonstrated that the fit of the raw data via the equation of state is as good as the smoothing of Selleck et al.
A numerical solution for the dispersion in laminar flow through a circular tube
Authors: Takahashi Teruo , Korenaga Takashi , Shen Fenghua
Published: March 2009

A numerical solution based on the method proposed by Bailey and Gogarty was developed to describe the solute dispersion in laminar flow through a straight tube of circular cross section. Many studies have been carried out since Taylor (1953) first presented a partial differential equation to describe the problem. The advantages of the present numerical solution are that it involves less numerical computation than others and can give very accurate results. It is also convenient to use because of its simplicity. The results obtained by this solution are in excellent agreement with those of Yu's solution, which is considered to be the most satisfactory approximation among the previous studies. The numerical solution also agrees very well with the experimental results for a finite slug of dye solution dispersed into water in laminar tube flow. A method was developed to check the computing error by means of a mass balance on the solute.
Hydrodynamic and thermal modelling of a high temperature spouted bed reactor with a draft tube
Authors: Stocker Rudolf K. , Eng John H. , Behie Leo A.
Published: March 2009

A new multi‐region, nonisothermal computer model of a spouted bed reactor with a draft tube has been developed. The model rigorously accounts for the mass, momentum, and energy interactions between the annulus and the spout both above and below the base of the draft tube. Additional reaction due to the residence time of the gases in the fountain region is also accounted for. Investigations involving the ultra‐rapid ultrapyrolysis of propane indicate that a spouted bed reactor with a draft tube is ideal for very fast reactions of this type as both high heating rates and short reactant gas residence times can be achieved within the reactor. Simulations indicate the reactor to be capable of heating the spout gases at maximum rates between 50 000 and 90 000 K/s. Gas residence times of 30 ms or less within the draft tube and 400 ms or less in the reactor were predicted by the model for conditions typical of those required for propane ultrapyrolysis.
Chemical enhancement in the determination of KLa by the sulfite oxidation method
Authors: Thibault Jules , Leduy Anh , Denis Alain
Published: March 2009

Results obtained by Ogut and Hatch (1988) for oxygen transfer rate into mechanically agitated Newtonian fluids are examined. Results indicate that volumetric oxygen transfer coefficients measured by the sulfite oxidation method can be much higher than the oxygen transfer coefficients obtained by other methods if the concentration of cobalt, used to catalyse the reaction, is above a certain critical concentration.
On structural changes of lignite char during fluidised bed combustion
Authors: Haldar S. , Saha R. K.
Published: March 2009

Experiments were conducted to study structural changes (diameter, specific surface area and density) and mode of combustion of lignite char in a fluidised bed combustion process. Analysis of data demonstrates the effect of attrition along with combustion. Internal burning at least to the extent to which burn off has been studied, does not play a significant role. Despite attrition effects, the change in diameter approximates that of an idealised shrinking sphere.
Performance of combined mesh packing and sieve tray in distillation
Authors: Chen G. X. , Afacan A. , Xu C. , Chuang K. T.
Published: March 2009

The hydraulic and mass transfer performance of a combined knitted mesh packing and sieve tray has been measured for the distillation of methanol‐water mixtures. It was found that by adding a shallow bed of packing, the Murphree tray efficiency increased by 40–50% over a wide range of concentrations and flow rates. This increase in tray efficiency can be attributed to a much smaller and more uniform bubble formation on the packed tray. Hydraulic measurements have shown that the packed trays have lower weeping and entrainment, as well as slightly higher froth heights and pressure drops.
Modelling a uranium ore bioleaching process
Authors: Chien Daniel C. H. , Douglas Peter L. , Herman Dennis H. , Marchbank Andrew
Published: March 2009

A dynamic simulation model for the bioleaching of uranium ore in a stope leaching process has been developed. The model incorporates design and operating conditions, reaction kinetics enhanced by Thiobacillus ferrooxidans present in the leaching solution and transport properties.

Model predictions agree well with experimental data with an average deviation of about ± 3%. The model is sensitive to small errors in the estimates of fragment size and ore grade. Because accurate estimates are difficult to obtain a parameter estimation approach was developed to update the value of fragment size and ore grade using on‐line plant information.
Reactive crystallization of calcium carbonate by gas‐liquid and liquid‐liquid reactions
Authors: Kotaki Yasushi , Tsuge Hideki
Published: March 2009

Crystallization of calcium carbonate by gas‐liquid and liquid‐liquid reactions in a continuous MSMPR crystallizer was conducted over a wide range of suspension densities. The effects of operating factors and reaction mechanism on the cyrstallization kinetics were investigated.

The crystallization kinetics for both reaction systems are correlated by the power law model and these correlations depend on the suspension density regions. The kinetic orders in the power law model are correlated with carbonate alkalinity irrespective of the reaction mechanism and the suspension density.
Implications of standard states and ideal solution in terms of Raoult's law
Authors: Peng Ding‐Yu
Published: March 2009

Traditionally, Raoult's law has always been considered to describe the vapor‐liquid equilibrium of ideal solutions. This treatment not only is awkward but also is not in complete agreement with the definition of an ideal solution in the sense of the Lewis‐Randall rule.

In this study, the characteristics of a model system of Raoult's law are analyzed. The analysis is based on the application of the Lewis‐Randall rule in which the actual states of the pure components are used as the standard states. It is shown that, in the region where vapor‐liquid equilibrium exists, neither the vapor nor the liquid is an ideal solution in the strict sense of the Lewis‐Randall rule.
A corresponding states treatment of saturated density, surface tension and capillary constant of cryogenic liquids and refrigerants
Authors: Srinivasan K.
Published: March 2009

Using a new set of energy (kT) and length (σ) parameters, a corresponding states treatment is applied to the calculation of some thermophysical properties in a generalised non‐dimensional form. The saturated density is well represented by the following equation:

for all the liquids studied here. The surface tension correlations are \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _r^* = 2.055\left({1.219 - T_r^*} \right)^{1.240} $\end{document} for cryogenic fluids and hydrocarbons and \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _r^* = 2.322\left({1.228 - T_r^* } \right)^{1.244}$\end{document} for refrigerants. An interpretation of the index in the density equation and the constants in the surface tension equations is given. Using these correlations, an equation is also proposed for the capillary constant.
Absorption of CO2 by aqueous diethanolamine (DEA) solutions in a high shear jet absorber
Authors: Chakma A. , Chornet E. , Overend R. P. , Dawson W. H.
Published: March 2009

CO2 diluted with N2 was absorbed by aqueous DEA solutions in a high shear jet absorber consisting of a high pressure stainless steel vessel with a pressure nozzle at the top. The results show that equilibrium conditions can be rapidly reached under high shear conditions. CO2 removal expressed by moles of CO2 absorbed per mole of DEA increased with gas flow rate and decreased with liquid flow rate. The overall mass transfer capacity coefficient Kg a was found to increase with gas flow rate and solution concentration. Kg a went through a maximum with solution flow rate. Increasing the CO2 partial pressure was found to decrease Kg a.
Deactivation of ICI low temperature methanol catalyst in an industrial reactor
Authors: Islam K. A. , Earl W. B.
Published: March 2009

The deactivation behavior of one of the ICI low temperature methanol catalysts (ICI‐51‐Z) in a typical ICI multibed quench reactor has been studied in relation to methanol production with respect to time of operation, using some representative sets of plant data collected over two years time span. A pseudo‐homogeneous first order model of the methanol synthesis reactor was formulated for this purpose. The best set of catalyst deactivation parameters for different beds was found using a nonlinear parametric estimation technique. Catalyst in the entering bed was found to deactivate most with the time of operation, while subsequent beds deactivate progressively less quickly.
Modélisation et simulation du séchage en continu des couches minces par rayonnement infrarouge
Authors: Cote Benoit , Broadbent Arthur D. , Therien Normand
Published: March 2009

Basé sur des concepts de transferts simultanés de masse et d'énergie, un modèle différentiel est posé pour le séchage en continu des couches minces par rayonnement infrarouge. Des essais conduits sur le séchage d'une nappe de coton non‐mercerisé dans un séchoir semi‐industriel d'une capacité maximale de 20 kW ont servi à la calibration du modèle. Les simulations, par intégration numérique des bilans de masse et d'énergie, fournissent les conditions à la sortie du séchoir: température de l'air, température du tissu et degré d'humidité résiduelle dans la nappe. Une étude de sensibilité indique que la température des émetteurs infrarouges est le paramètre qui influence le plus significativement le séchage. Les résultats montrent également que l'air alimenté sert presqu'uniquement à évacuer la vapeur produite, le transfert de chaleur par convection étant faible par rapport au rayonnement.