bluuebunny/crossref_metadata_2025 huggingface dataset:
An accelerated successive substitution algorithm
Authors: Mehra R. K. , Heidemann R. A. , Aziz K.
Published: March 2009

Three related proposals are made for accelerating the familiar successive substitution procedure for phase equilibrium flash calculations. Basic to the development of the acceleration procedures is the observation that successive substitution can be regarded as a method of steep descent for free energy minimization. Acceleration is obtained by choosing an optimal step length. Results show a significant decrease in the number of iterations required for convergence, even in difficult problems near the mixture critical point.
Saturation and metastable properties of the van der waals fluid
Authors: Shamsundar N. , Lienhard John H.
Published: March 2009

Modern applications require accurate thermodynamic equations of state that portray stable and metastable states of fluids. Earlier work has shown that the famous van der Waals equation, contrary to widely held views, finds its natural niche in the rank of real substances ordered according to their values of the acentric factor. In this note, the saturated and metastable state properties of a van der Waals fluid are presented in the form of a temperature table and a pressure table. A comparison of these results with the available data for mercury is made and it is established that mercury is approximated rather well as a van der Waals fluid.
Effects of temperature and time on interfacial tension behavior between heavy oils and alkaline solutions
Authors: Babu Dasari Ram , Hornof Vladimir , Neale Graham
Published: March 2009

Heavy oils contain significantly more acidic components than conventional crude oils. Upon contact with aqueous alkaline solutions, water‐soluble surfactants are formed in‐situ at the interface. These surfactants have the ability to reduce the oil/water interfacial tension to ultra‐low values. This work studies the significant effects of time and temperature on the interfacial tension between alkaline solutions and two Canadian heavy oils (Lloydminster and Cold Lake). The results obtained indicate that the time period during which interfacial tension remains ultra‐low is just as important as the magnitude of the minimum attainable interfacial tension in determining the potential success of an alkaline flooding process in the field.
Experimental design techniques applied to the domtar dryformer
Authors: Grandmaison E. W. , Kerr R. B. , Robillard M.
Published: March 2009

The variables affecting the peformance of the Domtar pilot plant dryformer have been examined using experimental design techniques. A total of fifteen variables were incorporated in a 215−11 fractional factorial design with a reverse sign design to obtain the main effects of variables free of aliasing with other main effects and two‐factor interactions. An estimate of experimental error was obtained from repeated runs of the primary 215−11 design conditions.

The experiments were performed with bleached softwood kraft pulp and the dependent variables included the production rate at good formation, the production rate with adequate nit removal, the machine direction basis weight variation and the average formation characteristics of the dryformed web product. Of the fifteen variables examined, all but three have some effect on at least one of the dependent variables and there were strong indications that two‐factor interactions played an important role in describing the operation of this dryformer.
Holdup and flooding in reciprocating plate extraction columns
Authors: Baird M. H. I. , Shen Z. J.
Published: March 2009

Measurements of dispersed phase holdup and flooding conditions have been carried out in a 5 cm diameter reciprocating plate extraction column. A simplified predictive model for holdup and flooding has been developed assuming uniform hydrodynamic conditions throughout the column. The model has been confirmed for several systems but may be limited in application by the following factors: (a) mass transfer, particularly from dispersed to continuous phase (coalescence effect), (b) wettability of plates by dispersed phase, (c) axial non‐uniformity of holdup (noticed particularly for high interfacial tension systems), (d) the use of exceptionally high frequencies or low amplitudes of agitation.
Continuous fermentation — And new horizons
Authors: Dawson P. S. S.
Published: March 2009

Continuous processes for cultivating microbes have not been very successful in application because the variable nature of microbial activities do not conform to the rigid stoichiometrics of chemical reactions and fixed physical constants. Such difficulties require enlightened approaches and new perspectives with emphasis on inter‐ and multi‐disciplinary interactions. The new area of continuous synchronized growth, which enables cellular activity to be focussed, used and exploited on the basis of the cell, and life processes to be considered on an absolute basis, is discussed.
Characterization of helical impellers by circulation times
Authors: Guérin P. , Carreau P. J. , Patterson W. I. , Paris J.
Published: March 2009

Measurements of the circulation time during batch mixing of Newtonian and non‐Newtonian fluids were used to analyse and compare the performance of six different helical‐ribbon impellers and a screw impeller inside a draft coil. The distribution of circulation times obtained from two hundred repeated measurements is shown to depend markedly on the impeller geometry. Mixing time data with the helical‐ribbon impellers are correlated with the mean value and the reduced standard deviation of the circulation times. Effective (rapid) mixing corresponds to a large circulation capacity and a wide distribution of the circulation times. The mixing mechanism of Newtonian fluids with the helical‐ribbon impellers is qualitatively described by the Voncken model.

The helical impellers' circulation capacities are not affected by the shear‐thinning properties of non‐Newtonian fluids. However, in highly shear‐thinning fluids, the presence of important stagnant zones is responsible for much longer mixing times which consequently do not correlate with the circulation parameters.

The relative efficiencies of the different impellers in Newtonian fluids are compared using a criterion based on the the total energy required to achieve a certain degree of mixing. The wide blade impeller is the most efficient of the helical‐ribbon impellers but is considerably less efficient than the screw impeller in a draft coil.
Forced convection heat transfer to a power‐law fluid in arbitrary cross‐section ducts
Authors: Lawal Adeniyi , Mujumdar Arun S.
Published: March 2009

A numerical method is developed to predict the three‐dimensional forced convection laminar incompressible flow of a power law fluid in arbitrary cross‐section straight ducts. The continuity equation and boundary layer forms of the energy and momentum equations in rectangular coordinates are transformed into new orthogonal coordinates with boundaries coinciding with the coordinate surfaces. The resulting equations are solved using the finite difference technique.

The numerical scheme is capable of handling different hydrodynamic and thermal entry boundary conditions but results are only presented for uniform inlet velocity and temperature profiles and isothermal wall.

To demonstrate the wider applicability of the method local heat transfer coefficients and pressure drop in square, trapezoidal and regular pentagonal ducts are computed as functions of pertinent thermal and hydrodynamic parameters.
The continuous flash pyrolysis of biomass
Authors: Scott Donald S. , Piskorz Jan
Published: March 2009

A continuous atmospheric pressure flash pyrolysis process for the production of organic liquids from cellulosic biomass has been demonstrated at a scale of 1–3 kg/hr of dry feed. Organic liquid yields as high as 65–70% of the dry feed can be obtained from hardwood waste material, and 45–50% from wheat straw. The fluidized sand bed pyrolysis reactor operates on a unique principle so that char does not accumulate in the bed and treatment of the sand is not necessary. The product gas, about 15% of the yield, has a medium heating value. The liquid product is an acidic fluid, which pours easily and appears to be stable. A preliminary economic analysis suggests that if the pyrolysis oil can be used directly as a fuel, its production cost from wood waste is probably competitive with conventional fuel oil at the present time.
Prediction of flow pattern for the co‐current flow of gas and non‐newtonian liquid in horizontal pipes
Authors: Chhabra R. P. , Richardson J. F.
Published: March 2009

Previous work on delineating flow patterns for the horizontal two‐phase flow of gas and Newtonian liquid is briefly described. One of the flow pattern maps has been slightly adjusted to take account of the evidence from more recent studies. It is shown that physical properties of the system have relatively little influence on flow regime. It is then established that this map is also applicable when the liquid shows shear‐thinning non‐Newtonian properties.
Transfert de l'oxygène dans l'eau à température et pression élevées étude cinétique en réacteur agité par la méthode au sulfite
Authors: Foussard Jean‐Noel , Debellefontaine Hubert , Besombes‐Vailhe Jean
Published: March 2009

This paper examines the rate of absorption of molecular oxygen in an aqueous solution of sodium sulphite as a function of temperature over the range of 20–240°C. First, we determined the effect of the various parameters (oxygen partial pressure, sulphite and catalyst concentration, agitation) on the enhancement factor,E.It was observed that an Arrhenius' type relationship could describe the dependence of the physical absorption rate on temperature. According to the degree of agitation, two values for the activation energy: 22.8 and 12.7 kJ · mol−1are obtained. Our results validate the various models formerly proposed only for the range 10–40°C, but show that they cannot be extrapolated above 50°C. The results also show that a simple test at ambient temperature can be used to predict the oxygen transfer capability of a reactor at temperatures up to 240°C.
An experimental investigation of minimum fluidization velocity at elevated temperatures and pressures
Authors: Nakamura Masaaki , Hamada Yoichi , Toyama Shigeki , Fouda A. E. , Capes C. E.
Published: March 2009

Minimum fluidization data at elevated temperatures and pressures are relatively scarce in the literature. This study was undertaken to provide some new data under these conditions. Minimum fluidization velocities at temperatures up to 800°K and pressures up to 5 MPa were measured for uniformly‐sized glass beads with diameters between 0.2 mm and 4 mm in beds ranging in diameter from 30 mm to 50 mm. The experimental results are compared with a number of empirical correlations from the literature to determine the validity of the correlations under these elevated temperature and pressure conditions.
Correlations for bubble characteristics in fluidized beds
Authors: Viswanathan K.
Published: March 2009

For fluidized bed reactors the available equations for superficial bubble velocity (UB), bubble fraction (δ), and absolute bubble rise velocity (ub) do not include bed diameter as a variable. Based on the gross solid circulation model new expressions are derived for UB, δ, and ub which explicitly account for bed diameter. Existing data are compared to predicted values from these correlations.
Dynamic simulation of a multicomponent distillation column with asymmetric dynamics
Authors: Stathaki Anna , Mellichamp Duncan A. , Seborg Dale E.
Published: March 2009

The dynamic behavior of an existing industrial distillation column with eight components and twenty trays has been investigated. The column exhibits “asymmetric dynamics”, since the time required to move from one steady state to another can vary significantly depending on the direction of the change. The column also exhibits highly nonlinear behavior and very long response times for intermediate ranges of step disturbances. These long response times are associated with the migration of key components through the column.
Shear‐Thinning effects on dip coating
Authors: Tanguy P. , Choplin L. , Fortin M.
Published: March 2009

The dip coating operation with shear‐thinning fluids is simulated by the Augmented Lagrangian Method coupled to a finite element discretization. Numerical predictions of coating thickness and meniscus shape compared with experimental data exhibit a very poor agreement. The discrepancy of results is explained by the inadequacy of shear‐thinning rheological models to describe the dynamics of the coating process in a non‐purely viscometric situation and also by the presence of a weak level of elasticity in the fluids used.
Modelling and adaptive control of fed‐batch penicillin fermentation
Authors: Montague G. A. , Morris A. J. , Wright A. R. , Aynsley M. , Ward A.
Published: March 2009

This paper describes a study to investigate the application of state estimation and parameter adaptive control in fed‐batch fermentation for penicillin production. A model of the penicillin fermentation process is outlined and shown to be capable of matching industrial data. The penicillin mould biomass is controlled to a reference trajectory by applying self‐tuning control to an estimate of biomass, obtained from measurements of carbon dioxide production rate and fermenter volume and by using the fermentation model with an extended Kalman filter. The manipulated variable, sugar feed to the fermenter, is calculated by an adaptive algorithm. Simulation results compare the performance of self‐tuning control with that obtained using digital Proportional plus Integral control.
The metabolism of lidocaine in the liver: Steady‐state and dynamic modelling
Authors: Saville B. A. , Gray M. R. , Tam Y. K.
Published: March 2009

The elimination of the drug lidocaine by the liver was modelled as a chemical reactor system, using data from in‐vitro tests of liver metabolism. A network of reactions, based on the known metabolic pathways, was used to account for the observed concentrations of drug and reaction products in steady state. The rates of reaction were substantially higher than in a liver homogenate, and some pathways showed considerable variation between individual livers. The steady‐state behavior of the liver was consistent with a well‐mixed reactor. The dynamic behavior could only be represented by including the additional mechanisms of enzyme deactivation and binding of drug to liver tissues.
Mixed‐culture microbial protein from waste sulfite pulping liquor II: Its production on pilot‐plant scale and use in animal feed
Authors: Lo S. N. , Moreau J. R.
Published: March 2009

This paper describes a pilot plant system set up to produce a mixed‐culture biomass having a very high content of protein (43%), for use in animal feed. Waste liquor from sulfite pulping was used as substrate. Conversion of carbohydrates in the said liquor to biomass was carried out in a 1200‐liter, nonaseptic, aerated, continuous flow tank fermentor. Fermentation conducted at pH = 6.5 gave rise to better settling of microorganisms than at the other pH's studied. The air input was a very important factor affecting fermentor productivity. Under the operating conditions used, the results for carbohydrate conversion, BOD5 reduction, biomass yield coefficient, and productivity were respectively, 90%, 85%, 0.53 kg/kg, and 3.67 kg/(m3d). With respect to the whole production system, operating and/or control problems were identified and useful technical data were collected in view of an eventual industrial implantation.

The final product consisted of about the same varieties of microorganisms (yeasts, bacteria and microfungi) obtained in our previous work, Its nutritive qualities were not affected by the scale‐up of fermentor, i.e., from the previous 400 liters to the present 1200 liters. Animal feeding experiments were conducted using 240 chickens fed 4 diets. At least 50% of the soybean protein in commercial diet could be replaced with the biomass protein, without creating a significant effect on growth performance, on the health status of animals examined ante‐mortem and post‐mortem, and on the organoleptic quality of chicken meat.
Prandtl number effect on combined free and forced laminar convection in the thermal entrance region of a horizontal rectangular channel
Authors: Chou F. C. , Hwang G. J.
Published: March 2009

A numerical method employing an axial‐direction vorticity function and three velocity components is applied to study the Prandtl number effect on the combined free and forced laminar convection in the thermal entrance region of a horizontal square channel. The channel wall is heated with a uniform heat flux. Local Nusselt number variations are shown for Rayleigh numbers Ra = 104, 3 × 104, 6 × 104 and 105 with the Prandtl number as a parameter. It may be concluded that the large Prandtl number assumption is valid for Pr = 10 when Ra≤104 but for a larger Prandtl number when the Rayleigh number is higher.
High alcohol synthesis from CO and H2 on ruthenium catalysts
Authors: Chen Yu‐Wen
Published: March 2009

A Ru/MoO2 catalyst was found to be active for the synthesis gas conversion to straight chain primary alcohols. Potassium carbonate was effective for enhancing high alcohol formation. The carbon number distribution of the alcoholic products followed the Anderson‐Schulz‐Flory distribution which gave chain growth probabilities of 0.27–0.35. In addition, the Ru/MoO2 catalysts are significantly more sulfur resistant than a Ru/Al2O3 catalyst. The higher sulfur resistance of these catalysts is mainly due to their higher sulfur adsorption capacities.
Measurement of particle movement in a spouted bed using a new microprocessor based technique
Authors: Waldie B. , Wilkinson D.
Published: March 2009

A new experimental technique for measuring particle cycle times, times of occurrence of particles at different levels, and particle velocities in the spout of a spouted bed is described. A magnetized marker particle and search coil or coils are employed together with a microprocessor system for ease of data collection and processing. The magnetic particles have the same diameter, density and similar surface texture to bed particles to ensure proper representation.

Data is presented on distributions of cycle time and particle velocity and implied particle mass circulation rates at different levels in a spouted bed. Comparisons are made with photographic and laser–doppler anemometry techniques.
A mathematical model for the dehydrogenation of methylcyclohexane in a packed bed reactor
Authors: Touzani A. , Klvana D. , BÉLanger G.
Published: March 2009

A model for the dehydrogenation of methylcyclohexane in a tubular reactor over an industrial catalyst Pt‐Sn/Al2O3 has been established. This model takes into account the axial dispersion at the inlet of the catalytic bed reactor as well as the heat transfer at the wall of the reactor. The heat transfer at the wall is satisfactorily represented by using a heat transfer coefficient correlation for which the parameters are obtained by fitting to the experimental data. The model provides a good representation of the radial and axial temperature profiles in the packed bed and can be also used to calculate the conversion.
Permanent jet formation in beds of particulate solids
Authors: Grace J. R. , Lim C. J.
Published: March 2009

The simple criterion proposed by Chandnani and Epstein (1984, 1986) for stable spouting, dor/dp ≤ 25.4, is shown to give a good separation between gas‐solid systems which form permanent jets and those that bubble, for a wide range of experimental data reported in the literature. The criterion is suggested as a necessary but not sufficient condition for permanent jet formation in fluidized, spout‐fluid and spouted beds.
Axial mixing and scaleup of reciprocating plate columns
Authors: Karr A. E. , Ramanujam S. , Lo T. C. , Baird M. H. I.
Published: March 2009

Axial mixing measurements in single phase (water) flow have been taken in open‐type reciprocating plate columns of diameters 25.4 and 508 mm. In the case of the smaller column, two‐phase axial mixing was measured, both in the dispersed phase (water dispersed in n‐heptane) and the continuous phase (with n‐heptane dispersed in water). Pulse injection of a tracer solution of ammonium chloride and methanol in water was used.

Under single phase conditions, the axial dispersion coefficients were found to go through a minimum as the agitation level was increased from zero. The coefficients were nearly an order of magnitude higher in the 508 mm column than in the 25,4 mm column. In two phase flow in the 25,4 mm column, the continuous phase axial dispersion coefficients also went through a minimum as agitation was increased. The dispersed phase axial dispersion coefficients decreased monotonically as agitation was increased from zero. The results of this work and previous data are used in modelling the scale‐up of reciprocating plate columns by means of Pratt's simplified technique. The existing empirical scale‐up equation is consistent with an assumption that continuous phase mixing increased with column diameter but dispersed phase mixing remains unchanged.
Study of a novel uniflow cyclone design
Authors: Sumner R. J. , Briens C. L. , Bergougnou M. A.
Published: March 2009

A 5 cm diameter scale‐down model of a new uniflow cyclone for the ultra‐rapid fluidized (URF) reactor with a gas residence time under 20 milliseconds has been tested at high solids loading (5/1 wt. solids/wt. gas) under cold modeling conditions. The body length, gas exit diameter and amount of gas withdrawn with the existing solids (gas underflow) were varied to obtain high separation efficiency (over 99.9%). Silica sand of 55 and 105 micrometer Sauter mean diameter was used. Grade efficiency curves were determined for several specific configurations to get a deeper understanding of the mechanisms influencing the separation.
Solids mixing kinetics and segregation in a vibrostabilized fluid bed
Authors: Beeckmans J. M. , Chu J. C. H.
Published: March 2009

The vibration‐induced reduction in internal mobility of a fluidized bed, which was reported in a recent paper (Beeckmans and MacWilliam, 1986), has been confirmed using a larger bed. It has now been found that above a particular fluidization velocity internal mobility is not affected by vibrations. Distributor grid geometry was found to have a small effect on the fluidizing gas velocity at which bubbles are first observed at the surface of the bed, but it had an insignificant effect on solids mixing rates. The extent of segregation at steady state was reduced by vibrations with both flotsam and jetsam tracer particles.
A mixing model for diagnosing reacting tracers and tracing reactants in chemical and biochemical processes
Authors: Tanner Robert D. , Debelak Kenneth A. , Rohani Sohrab , Dunn Irving J. , Bourne John R.
Published: March 2009

It has previously been shown (Tanner et al., 1985) that biochemical and chemical reaction processes of the Type A → B → C can lead not only to kinetic hysteresis between the rate of formation of C and the concentration of species B in batch processes, but also hysteresis between those variables in a closed, imperfectly mixed (two zone) batch reactor. Furthermore, crossplotting the intermediate reactant, B, in one region of the poorly mixed reactor against B from the other major region leads to a clockwise hysteresis curve which is defined by both its area and the coordinate phase angle. This paper shows that the earlier analysis (Tanner et al., 1985) can be extended to the more general system A → B, where A in one region of the vessel is crossplotted against A measured in the other region. With an initial concentration of A* in one zone equal to its highest concentration, the inscribed area double‐valued crossplot of A, uniquely defines the system in terms of the inter‐vessel flowrate to reaction rate constant ratio, D/k.
Experimental investigation of cocurrent two‐phase flow in a vertical rectangular channel
Authors: Moujaes S. , Dougall R. S.
Published: March 2009

New time averaged data of two‐phase flow in bubbly and slug regimes are presented. A modified dual spherical tipped optical fiber probe is used to measure local void fractions, gas velocity and bubble sizes. Hot film anemometry was used to measure the local mean liquid velocity axially. The void fraction, gas and liquid velocities values were presented as averages over the long and short dimensions respectively. Also core values of these variables are presented along the smaller dimension of 12.7 mm, near the plane of symmetry of the longer dimension, to show the most general trend of the different bubbly and slug flow runs. Bubble sizes obtained experimentally were compared with predictive models applied to circular geometries and were found to have a reasonable agreement. It was also interesting to find that local void fractions measured using hot film anemometers were comparable to those found by optical fiber probes.

Frequencies of interfacial passage of bubbles and slugs are presented which show rather flat profiles across the channel. It is hoped that these data can be further used in predictive two‐phase two‐fluid models in the future. Lastly of interest is the fact that slip values near the boundaries were shown to be less than 1.0 for some cases in bubbly flow similar to those observed in circular geometries.
Motion of a two‐phase bubble through a quiescent liquid
Authors: Wanchoo R. K. , Raina G. K.
Published: March 2009

The motion of a two‐phase bubble in immiscible liquids is associated with the development of three‐phase heat exchangers applicable for heat transfer at low driving forces.

An analytical expression for the instantaneous velocity of a two‐phase bubble moving through a quiescent, less viscous, immiscible liquid has been developed. This expression predicts, very well, the available experimental data over the whole operational range of temperature and initial drop diameter.
Formation and growth mechanism of porous, amorphous, and fine particles prepared by chemical vapor deposition. Titania from titanium tetraisopropoxide
Authors: Kirkbir Fikret , Komiyama Hiroshi
Published: March 2009

The formation and growth mechanism of porous, amorphous, and fine particles were investigated. TiO2 particles were produced in a tubular flow reactor by a chemical vapor deposition technique using titanium tetraisopropoxide as a starting material at low temperatures (573‐973 K) and atmospheric pressure. Prepared particles were of submicron size and had large surface area (as large as 270 × 103 m2/kg). According to the proposed mechanism, reactions begin on the reactor wall and then the primary particles form in the gas phase by chemical reactions. The primary particles collide, coalesce with each other and grow. However, significant experimental deviations from the Brownian collision and coalescence theory imply that other processes, such as the surface reactions on the particle, play an important role in the growth, in addition to coalescence. Intraparticle reactions decreased the surface area by filling the pores.
On the determination of kinetic parameters for the regeneration of cracking catalyst
Authors: Morley K. , De Lasa H. I.
Published: March 2009

In the study of the regeneration of cracking catalyst, two approaches may be taken when determining the kinetic rate constant for the coke combustion reaction. A global coke burning rate equation may be considered, based on the observed oxygen concentration and carbon dioxide to carbon monoxide molar product ratio. This reaction may also be represented by an intrinsic coke burning equation which is a function of the oxygen concentration and the carbon dioxide to carbon monoxide molar ratio at the reaction site, combined with a carbon monoxide postcombustion equation. It is proposed in this paper that the rate constant for intrinsic coke burning, kc, is essentially equal to the global coke burning rate constant, kc, and that its value is independent of the rate equation chosen for the carbon monoxide post‐combustion reaction.
Prediction of mass diffusivity of CO2 into bitumen
Authors: Mehrotra Anil K. , Garg Anju , Svrcek William Y.
Published: March 2009

The infinite dilution and mutual diffusion coefficients for the CO2/bitumen system were predicted using existing correlations. Out of seven semi‐empirical correlations tested, the Umesi‐Danner correlation was found to be best suited for the prediction of gas‐liquid infinite dilution diffusion coefficient. For the mutual diffusion coefficient, Teja's method based on the generalized corresponding states principle was successfully used. The predictions are compared with the limited CO2/bitumen diffusivity data available in the literature.
Use of sewage sludge for manufacturing adsorbents
Authors: Chiang P. C. , You J. H.
Published: March 2009

This paper demonstrates that digested sludge can be reclaimed as an adsorbent for the removal of organic vapors (MEK, TOL and TCE) through the use of a pyrolysis. The manufactured adsorbent products were characterized by Brunauer, Emmentt and Teller (BET) surface area, carbon tetrachloride activity (ANSI/ASIM D3467–76'), and an elemental analysis test. Both the determination of CCl4 activity and BET surface area were regarded as the useful means for estimation of the adsorption capacity of organic vapors on the reclaimed adsorbents.

From the view point of specific surface area (CCl4 activity number or adsorption capacity), it was concluded that the optimum condition for manufacturing the reclaimed adsorbent was by adding 5 kmols/m3 ZnCl2 to the treated sludge and then heating the mixture at 550°C for 1 hour.
Ventilation of a dead‐end duct having a porous barrier
Authors: Ryan J. T. , Griffin Wayne H.
Published: March 2009

Analytic expressions for the flow and pressure in a dead‐end duct which has loss of fluid through a porous wall are developed. The presence of an obstruction or auxiliary fan at the end of the duct is included. In either case there is a maximum permissible length of duct. As the duct length approaches this maximum, the main supply fan power and flow increase dramatically.

There is no recirculation within the duct when there is an obstruction at the end of the duct. If an auxiliary fan is used, there is always recirculation. However the use of an auxiliary fan can yield major savings in total power requirements.
Influence of operating conditions on particulate fouling
Authors: Müller‐Steinhagen H. , Reif F. , Epstein N. , Watkinson A. P.
Published: March 2009

The influence of flow velocity and particle size on the deposition of suspended alumina particles onto heat transfer surfaces was measured with two fouling probes, namely, a heated cylindrical rod in an annulus and a coiled wire in crossflow. Additionally, the response of the fouled probes to such changes as may occur in operating heat exchangers was investigated. The measured influence of flow velocity, wall temperature, bulk temperature, heat flux, particle concentration and particle size on the fouling behaviour as described in this paper and in a companion paper is compared to the predictions of several fouling models from the literature, and recommendations are made for further improvement of these models.
Cinétique de dégagement des matières volatiles lors de la pyrolyse d'électrodes de carbone industrielles
Authors: Tremblay FrançLois , Charette Andre
Published: March 2009

Dans un complexe de fabrication d'aluminium, le procédé de cuisson des anodes donne lieu à une libération importante de matières volatiles combustibles. Le présent travail vise à mieux comprendre la cinétique de dégagement de ces substances. À cette fin, un dispositif thermogravimétrique de grandes dimensions a été mis au point de façon à pouvoir simuler le mieux possible l'environnement industriel. Des échantillons de deux masses distinctes ont été soumis à la pyrolyse à différents régimes de chauffage. La perte de poids et les concentrations des gaz dégagés ont été enregistrées tout au long de la montée en température. Les résultats cinétiques sont rapportés pour le méthane, l'hydrogène et le goudron. L'ordre de réaction ne varie pas avec la vitesse de chauffage alors que l'énergie d'activation et le facteur pré‐exponentiel augmentent. De plus, pour les grosseurs d'échantillons étudiés, il a été trouvé que la masse du solide n'influence pas la valeur des paramètres cinétiques.
Liquid‐liquid equilibria of the system water + acetic acid + methyl propyl ketone
Authors: Bianco A. , Correa J. M. , Arce A. , Correa A.
Published: March 2009

This article reports equilibrium data for the binary liquid‐liquid system water + methyl propyl ketone at temperatures in the range 20‐55°C, together with solubilities and equilibrium compositions of the ternary system water + acetic acid + methyl propyl ketone at 25, 35, 45 and 55°C. NRTL and UNIQUAC equations have been fitted to the experimental data for the ternary system, which are likewise compared with the values predicted by the group contribution method UNIFAC.
Determination and correlation of axial‐mixing parameters in an agitated liquid‐liquid extraction column
Authors: Steiner Ladislav , Kumar Anil , Hartland Stanley
Published: March 2009

Dispersion coefficients were measured in a pilot‐plant sized agitated liquid‐liquid extraction column of the Kuhni type. Available techniques were considered, and the axial mixing in both phases obtained over a broad range of operating conditions, both with and without mass transfer and with two sets of stator plates. Earlier correlations for backmixing in the continuous phase were checked and improved, the final equation being successfully tested on available published data.
Hydrocracking of n‐heptane with a NiO‐MoO3/HYUS zeolite as catalyst. Kinetic study
Authors: Vázquez M. I. , Escardino A. , Aucejo A.
Published: March 2009

The hydrocracking of n‐heptane has been carried out in a fixed bed reactor at 2.45 MPa pressure and with a H2/n‐heptane molar ratio of 5.0 using a 4 wt% NiO ‐ 8 wt% MO3/HYUS zeolite as a catalyst. The W/F10 ratio was varied between 75.3 and 1624 kg · s/kmol at different reaction temperatures: 573, 588, 603 and 623 K.

The kinetics of the reaction has been studied by two different procedures due to the slight deactivation of the catalyst. One of them uses the conversion and yield values extrapolated at time on stream to zero and the other uses a kinetic equation where the deactivation of the catalyst has been included. The experimental data were fit well by a pseudo‐first order kinetic equation and the kinetic constant values obtained by both methods coincide. The apparent activation energy of the reaction has a value of 105.8 + 5.0 kJ/mol.
Gas holdup in a two‐phase vertical tubular reactor at high pressure
Authors: De Bruijn T. J. W. , Chase J. D. , Dawson W. H.
Published: March 2009

Gas holdup in a tubular reactor was measured at pressures from 5 to 14 MPa at 300°C using a differential pressure cell. The effects on gas holdup of gas density, liquid superficial velocity and gas superficial velocity were studied using vacuum tower bottoms from a Venezuelan feedstock with 95.1 wt% +524°C material. Hydrogen was used at superficial gas velocities from 0.7 to 2.0 cm/s.

The feed density at 15°C (0.1 MPa), 300°C (5.57 MPa) and 400°C (13.9 MPa) was measured and showed a linear decrease with temperature. Increased gas density at a constant temperature of 300°C increased the gas holdup at all superficial gas velocities. An increase in the liquid flow rate from about 0.04 to 0.1 cm/s did not affect the gas holdup.
Performance of packings for water distillation
Authors: Chuang K. T. , Miller A. I.
Published: March 2009

Distillation of water has been investigated in packed columns of 300, 500 and 750 mm diameter. Both ordered packings (Goodloe, Mellapak and Sulzer CY) and random packings (Hy‐Pak, Mini‐ring and Pall‐ring) were studied and performance compared. It was found that, with surface treatments, phosphor bronze packings show good performance and insignificant scale‐up factors. Plastic materials are not suitable for water distillation because of their poor wetting characteristics.
Kinetics of reactions involved in pvrolvsis of cellulose II. The modified kilzer‐bioid model
Authors: Agrawal Ravindra K.
Published: March 2009

At temperatures below 300°C, it has been shown that the pyrolysis of cellulose can be modeled in terms of a modified Kilzer‐Broido ((K‐B) Model. According to this model, cellulose decomposes via two competitive reactions, a dehydration reaction to form anhydrocellulose and a depolymerization reaction to form levoglucosan. Anhydrocellulose later decomposes to chars and gaseous products via two competitive reactions. Arrhenius parameters and a technique of estimating empirical constants from experimental data for the K‐B type reactions are presented. Comparison of the ability of the modified K‐B model and the three reaction model to predict weight loss, product yields and heat pretreated results are also made.
A method for the design of flexible distillation sequence
Authors: Wagler R. M. , Douglas P. L.
Published: March 2009

A simple method has been developed to optimally design a distillation sequence with a fixed degree of flexibility in feed composition and flowrate, and accounts for uncertainty in stage efficiency, K‐value and beat transfer coefficient calculations. The method minimizes a weighted cost function and ensures both optimal and feasible operation in the range of flexibility/uncertainty by using an approach termed “practical feasibility”. The method was tested on a 4 column distillation sequence separating a 5 component light alkane feed mixture. Results are presented to illustrate the effect of uncertainty on sequence cost and column overdesign.
Correlation and prediction of gas solubility in cold lake bitumen
Authors: Mehrotra Anil K. , Svrcek William Y.
Published: March 2009

The solubility data for pure light gases, namely N2, CH4, CO2 and C2H6, in Cold Lake bitumen are correlated by use of the Peng‐Robinson equation of state. Modeling Cold Lake bitumen as a mixture of three pseudocomponents adequately matched two sets of the gas‐solubility data. The critical properties and acentric factor for the bitumen pseudocomponents were estimated using the Kesler‐Lee correlations. For each gas‐bitumen pair, a single constant value of the binary interaction parameter is shown to predict the gas‐solubility data with average deviations ranging from 2 to 8%. Subsequently, these calculations were extended to predict the solubility of CO2+CH4 gas‐mixtures in Cold Lake bitumen. It is shown that the solubility predictions for the gas mixtures data are higher by approximately 6 to 9%.
Correlations for wall and particle shape effects on fixed bed bulk voidage
Authors: Dixon Anthony G.
Published: March 2009

Correlations have been derived, by both geometrical arguments and empirical treatment of data, for the bulk void fraction in a fixed bed. The void fraction has been correlated as a function of particle‐to‐tube diameter ratio for packings of spheres and equilateral solid cylinders. Prediction of void fraction for equilateral hollow cylinders can be made from the solid cylinder correlation, provided a correction factor is included that allows for internal voidage and interpenetration of packings.
Jet penetration and pressure drops in water spouted beds of fine particles
Authors: Morgan M. H. , Littman H. , Sastri B.
Published: March 2009

New expressions for the maximum spoutable height and spout pressure drop ratio are developed for fine particles spouted in water. The maximum spoutable height in both water and air systems is found to be dependent upon two dimensionless parameters, β and ALim. For fine particles spouted with water, the dimensionless pressure drop ratio depends only upon the voidage, ϵ at the bottom of the spout.
Experimental study of a new mechanically resistant adsorbent
Authors: Iovtchev K. , Nikolov L. , Elenkov D.
Published: March 2009

A new mechanically resistant adsorbent for SO2, removal from tail gases has been developed based on a solid porous support. The effect of the gas mixture composition on the dynamics of sulphur dioxide adsorption on this new adsorbent has been studied.

The results show that the behaviour of the new adsorbent, used in a fixed bed adsorption, is similar to that of classical carbon‐containing adsorbents. The values of mass transfer coefficients have been calculated for different experimental data. The breakpoint time can be determined from the solution of the differential equations of the system.
Characterization of dilute and dense phase vertical upflow gas‐solid transport based on average concentration and velocity data
Authors: Mok S. L. K. , Bergougnou M. A. , Molodtsof Y. , Large J.‐F.
Published: March 2009

Dilute, ‘dense phase 1’, and possibly a third regime‐‘dense phase 2’, were observed in a vertical 0.02 m diameter pneumatic conveyor using 210 μm sand particles. The transitions were marked by the alterations in the trend of the measured average solids hold‐up while varying the solids mass flowrate at constant air velocity. Hydrodynamic characteristics together with the transition criteria for the various transport modes were established. A novel regime diagram based on average gas velocities and solids mass flowrates was developed to identify the operating conditions for these regimes, as well as the limiting solids carrying capacities of the present conveyor. A probable cause of the dilute to dense phase transition is speculated upon.
Kinetic analysis of the liquid phase hydrogenation of 2‐ethyl‐hexenal in the presence of supported Ni, Pd and Ni‐S catalysts
Authors: Smedler Gudmund
Published: March 2009

The kinetics of the consecutive hydrogenation reactions 2‐ethyl‐hexenal → 2‐ethyl‐hexanal → 2‐ethyl‐hexanol were studied in the liquid phase in presence of commercial Ni, Pd and Ni‐S catalysts. The Pd and Ni‐S catalysts were extremely selective with respect to the formation of 2‐ethyl‐hexanal, while the full reaction sequence was readily catalyzed by nickel.

A Langmuir‐Hinshelwood model with dissociative hydrogen adsorption was found to be the most probable model, for all three catalysts. The proposal of dissociative hydrogen adsorption of the Ni‐S catalyst was supported by an independent gas‐phase experiment, using the H2/D2 exchange reaction as a model reaction for the hydrogen àdsorption process.
PRSV: The stryjek‐vera modification of the peng‐robinson equation of state. Parameters for other pure compounds of industrial interest
Authors: Proust P. , Vera J. H.
Published: March 2009

Pure ‐ compound ‐ parameters for the Stryjek‐Vera modification of the Peng‐Robinson equation of state, PRSV, are reported for sixty‐nine additional compounds of industrial interest. Errors in the reproduction of pure compound vapor pressure are normally below 1% at reduced temperatures lower than 0.7 At reduced temperatures higher than 0.7, for a few compounds for which data are scarce, errors are somewhat higher than 1%.
Pneumatic transport of solids in an inclined geometry
Authors: Klinzing G. E. , Rohatgi N. D. , Myler C. A. , Dhodapkar S. , Zaltash A. , Mathur M. P.
Published: March 2009

Flow studies were conducted in 0.0266‐m and 0.0504‐m glass pipes held at various angles of inclination. Measurements in these experimental setups included particle velocities, solid mass flow rates, and pressure drops in both the upper and the lower halves of the pipe. Visual observations of the flow patterns were made through the glass section. Particles used in this system included glass particles of 67‐, 450‐, and 900‐μm diameter, as well as iron oxide of 400‐μm diameter. Mass flows from the two halves of the pipe were obtained by splitting the flow with a knife‐edged separator. Experiments were also performed in a 0.0095‐m transfer line in an inclined loop. The angle of inclination of the test loop was varied from 0 to 90 degrees from the horizontal. The effect of angle of loop inclination, tube diameter, and particle characteristics on basic flow parameters were studied.
Hydrodynamics of three‐phase fluidized bed containing cylindrical hydrotreating catalysts
Authors: Song Gyung‐Ho , Bavarian Farshad , Fan Hang‐Shih , Buttke Robert D. , Peck Lawrence B.
Published: March 2009

Experiments were performed to study the hydrodynamic characteristics of a cocurrent, gas‐liquid‐solid fluidized bed containing cylindrical hydrotreating catalysts under conditions of high gas holdup. These conditions were established using an aqueous t‐pentanol (0.5 wt. %) solution as the liquid phase in an attempt to simulate reaction conditions for hydrotreating of residual oils and coal liquefaction. Separate three‐phase experiments were performed with air and water to investigate the effect of surface tension on hydrodynamic behavior.

A mathematical model was developed to describe the minimum fluidization velocity behavior. Bed voidage, gas holdup and terminal velocity of the particles were analyzed and correlated empirically to investigate the effect of particle shape and liquid surface tension. A bubble‐wakes interaction coefficient defined by Jean and Fan (1987) was determined for cylindrical particles.
Extraction and absorption with a vibrating perforated plate
Authors: Baird M. H. I. , Vijayan S. , Rao N. V. Rama , Rohatgi A.
Published: March 2009

Mass transfer rates and hydrodynamic behaviour have been measured for liquid‐liquid and gas‐liquid dispersions formed at small perforations (0.3 to 1.5 mm diameter) in plates vibrating at frequencies of 10–100 Hz and amplitudes in the order of 0.1 mm. The light phase (liquid or gas) is fed beneath the plate which is provided with a skirt so that the light phase passes through the perforations to form discrete drops or bubbles. Sauter mean diameter was generally in the range 1–2 mm.

Mass transfer efficiency for liquid‐liquid transfer (acetic acid from kerosene to water) was found to be in the order of 70% for a single plate; the effect of cell depth on efficiency was small, indicating that most of the mass transfer occurred near the plate. In the case of gas‐liquid mass transfer (oxygen uptake by water), the volumetric mass transfer coefficient was in the order of 0.1 s−1, which compares well with conventional equipment.
Catalytic reactions of methylcyclopentane on HY zeolite
Authors: Abbot J. , Wojciechowski B. W.
Published: March 2009

Catalytic reactions of methylcyclopentane have been studied on HY Zeolite at 500°C. Initial reactions include ring cleavage, the formation of paraffins and the formation of methylcyclopentane. Aromatic species are formed as both primary and secondary products. In contrast to the reaction of methylcyclopentane under reforming conditions, benzene is not a dominant initial aromatic product formed under cracking conditions. Unlike the reaction of cyclopentane on HY, the cracking of methylcyclopentane produces molecular hydrogen as an initial product. This we attribute to the presence of a hydrogen atom bonded to a tertiary carbon in the methylcyclopentane molecule.
Modelling of decomposition of a synthetic core of methane gas hydrate by coupling intrinsic kinetics with heat transfer rates
Authors: Jamaluddin A. K. M. , Kalogerakis N. , Bishnoi P. R.
Published: March 2009

Decomposition of a synthetic core of methane hydrate has been modelled by Selim and Sloan (1985) and Ullerich et al. (1987) based on heat transfer considerations. In the present work, the decomposition is modelled by coupling intrinsic kinetics with heat transfer rates. Numerical simulation results are presented to show the effects of incorporating the intrinsic kinetic rate of decomposition. Simulation results indicate that by changing the system pressure we can move from a heat transfer controlled regime to a regime where both heat transfer and intrinsic kinetics have a significant effect on the global rate of decomposition.