bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of forced cycling on the fischer‐tropsch synthesis. Part I. Response to feed concentration step‐changes
Authors: Feimer J. L. , Silveston P. L. , Hudgins R. R.
Published: March 2009

The response of the Fisher‐Tropsch synthesis to composition step‐change was studied as part of a larger study on the influence of forced feed composition cycling on the product distribution from this synthesis reaction. Using a promoted iron catalyst, studies were conducted at 384 kPa total pressure in a fixed‐bed differential reactor held at 246°C by means of an oil bath. It was determined that the reaction rate was not influenced by mass or heat transfer effects.

The maxima in the curves of steady state rate versus feed composition for various products occurred considerably above the stoichiometric ratio for each product olefin. This fact suggested that the rate was probably controlled by hydrogen adsorption in the initiation sequence. Support for this interpretation was also found from the response of the rates of production of light hydrocarbons (C2 to C5) to the step‐changes in feed concentration.
Gasification studies of onakawana lignite
Authors: Furimsky Edward
Published: March 2009

Onakawana lignite was gasified in air, steam and an air + steam mixture in a fixed bed reactor. The extent of devolatilization was determined by pyrolysis in nitrogen. The composition of products, expressed in terms of H2/CO ratio, was temperature dependent. The ratio decreased with increasing temperature. During steam gasification the ratio decreased from 4.6 to 2.6 when temperature increased from 700° to 990°C. The addition of air to steam resulted in a marked decrease of this ratio.

Steam gasification reactivity of chars prepared from Onakawana lignite at 500°C and 800°C were studied in the temperature range of 650°C to 1000°C. The carbon conversion results were fitted into equations describing the continuous and shrinking core models. The char prepared at 500°C was much more reactive than the one prepared at 800°C. Product distribution expressed as the H2/CO ratio, was favourable in the temperature range.

For comparison, the Kentucky #9 coal and chars derived from this coal were used as referee materials. The reactivity of these chars was markedly lower than that of chars derived from Onakawana lignite.
Application of lost‐product analysis to liquefaction processes
Authors: Leipziger Stuart , Huang Ching‐Chung
Published: March 2009

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

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

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

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

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

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

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

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

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

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

The interpretation of results of a chemical reaction carried out in a trickle bed reactor is not immediate when the key reactants are volatile; in fact some authors state that the overall conversion rate increases at very low liquid flow rates, i.e. when the catalyst is unevenly wetted. In these conditions, the reactants may penetrate inside the catalyst pellets directly through the “dry” zones; therefore the mass transfer resistance is diminished and the conversion rate can be increased.

To investigate this phenomenon tests on the catalytic oxidation of ethyl alcohol dissolved in water were performed at different operating conditions in a trickle bed reactor. An interpretation of the results was tried by using two different models based on partially wetted particles. This approach considers both the cases in which “dry” zones are active or not for mass transfer and mass transfer rates are affected or not by the chemical reaction.
Dynamic analysis of a fluidized bed reactor for sucrose inversion catalyzed by immobilized invertase
Authors: Doǧu Timur , Kaletunç Gönül , çaǧlar Arif
Published: March 2009

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

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

The influence of forced feed cycling was investigated on the product distribution from C1 to C9 of the Fischer‐Tropsch synthesis. A promoted iron catalyst in a small‐scale differential reactor at 246°C and 384 kPa total pressure was employed with square‐wave composition cycles generated at a constant flow velocity.

Except for methane, the product distribution during feed composition cycling followed the steady‐state Schulz‐Flory model. For some combinations of period, cycle‐split and mean composition, the time‐average methane rate was higher than the corresponding steady‐state rate. Decreasing the period increased the time‐average rate both for methane and other hydrocarbon products. High methane rates, found only during a partial cycle with pure hydrogen, indicated that methane was probably being produced by a parallel reaction path, the hydrogenation of a surface carbide. The methane reaction rate via this mechanism should be strongly inhibited by CO.

Product selectivity may be altered by forced composition cycling.
A study of the voltage and current efficiencies of fused salt AlCl3 electrolysis using bench scale cells
Authors: Hauksson Trausti , Foulkes Frank R.
Published: March 2009

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

Isobaric vapor‐liquid equilibrium measurements on binary mixtures of m‐ and p‐xylenes with carbon tetrachloride were taken at P = 40, 66.67 and 98.67 kPa.

The Wilson expression was used to correlate the experimental data. Only a weak deviation of the liquid phase from ideality is found. Activity coefficients of m‐ and p‐xylenes in carbon tetrachloride show negligible differences.
Computer simulation of fluid and plasma protein transport in the lungs
Authors: Bert Joel L. , Pinder Kenneth L.
Published: March 2009

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

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

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

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

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

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

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

Hydrogen sulfide/water mixtures are frequently encountered in the petrochemical and heavy water industries. Such mixtures exhibit an inherent foaminess when operating close to the liquefaction pressure of H2S. This can cause severe problems in fluid handling equipment.

Some nonionic surfactants are effective antifoams for these mixtures. The antifoam action is due to surfactant micelle formation which is enhanced by the presence of H2S through a “salting out” mechanism. The pressure at which a particular surfactant becomes an antifoam can be predicted from the hydrophobicity of the surfactant molecule. Such understanding could be applied to control foaming in other systems.
Prediction of operating range of rotor speeds for rotating disc contactors
Authors: Kamath M. S. , Subba Rau M. G.
Published: March 2009

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

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

Fouling of heat transfer surfaces modifies the associated conductive thermal resistance and convective heat transfer coefficient. Often, the latter varies as a result of changes in the roughness of the deposition surface. If fouling is being studied in an annular heat exchanger, deposits may form on both surfaces of the annular cross section, and an estimation of the friction factors of each fouled surface is needed. In order to evaluate these factors a simple method can be used as described in this paper, based on pressure drop measurements and current equations. Experimental results are reported and appear to support the method.
Trickle‐bed reactors: Effect of wetting geometry on overall effectiveness factor
Authors: Ring Z. E. , Missen R. W.
Published: March 2009

Calculations of the overall effectiveness factor in a trickle‐bed reactor are given that take into account liquid distribution on the external catalyst surface. Two cases are examined: nonvolatile limiting reactant (A), and limiting reactant present in both fluid phases (B). Parameters investigated, for first‐order, isothermal kinetics, are: number of wetted and nonwetted zones, particle shape, Thiele Modulus, wetting efficiency, and Biot numbers. The calculated results fall within the range of limiting solutions obtained independently. For case A the difference between 2‐ and 8‐zone models may reach 40% within the commercially important range of the Thiele modulus. For case B it probably does not exceed 25%. Comparison is also made with experimental data. It is concluded that a multizone model can be useful in the analysis. A new form of approximate model is proposed for case A.
A comparison between a conventional submerged culture fermenter and a new concept gas/solid fluid bed bioreactor for glutathione production
Authors: Bauer Werner
Published: March 2009

Glutathione is produced conventionally by submerged culture fermentation with yeast S. cerevisiae using L‐cysteine, L‐glutamate, and glycine as precursors. To obtain high glutathione concentrations, as well as high reaction rates, optimum temperature and high precursor concentrations have to be applied. Therefore, due to dilution in submerged culture, large quantities of precursor are needed. On the other hand, in solid state fermentation, increased precursor concentration is reached by the reduction of the water holdup in the fermenter. Experiments were performed to compare submerged culture fermentation in a stirred tank reactor with solid state fermentation in a gas/solid fluid bed bioreactor. In a 1.5 L stirred tank reactor the influence of temperature, substrate composition, and precursor concentration on reaction rate and maximum glutathione accumulation in the yeast cells was evaluated. A laboratory scale fluid bed fermenter of 0.15 m diameter and a pilot scale fermenter of 1.0 m diameter with 42 kg of yeast load were used to evaluate the optimum feed strategy to optimize glutathione yield with respect to precursor feed and glutathione accumulation in the yeast cells. In submerged culture, the maximum glutathione yield with respect to the precursor cysteine at maximum glutathione accumulation ranged from 4 to 8 mole %, whereas, with the gas/solid fermentation, yields of up to 40 mole % were obtained.
Modelling of the acetone‐butanol fermentation with cell retention
Authors: Mulchandani A. , Volesky B.
Published: March 2009

A mathematical model for the kinetics of the acetone‐butanol fermentation by Clostridium acetobutylicum was developed reflecting the biochemical pathway and culture behavior.

Steady‐state concentration of the process parameters in a cell‐retention (CR) fermentation were predicted by computer process simulation. It was established that the product concentrations are independent of the dilution rate ((DF), whereas the accumulated biomass concentration increased linearly with respect to the dilution rate. The predicted effect of the glucose feed concentration (So) on steady‐state concentrations of the process parameters showed that for values of So greater than 52.0 g/L the CR fermentor cannot attain a steady‐state.
Generalized linearization technique for first order process systems control analyses
Authors: Deyoung Thomas , Whitney Sarah , Schruben Dale
Published: March 2009

First order systems have primary elements such as generic flows and driving forces, as well as derived quantities such as capacitance and resistance. A text on control theory (Coughanowr and Koppel, 1965) describes the latter two quantities as primary elements denoted in differential form. This work extends that differential concept to nonlinear first order systems. Results of classical linearization theory (for example, linearized time constants) are then obtained with more ease.
Mixed convection flow of a power‐law fluid in horizontal ducts
Authors: Tomcej R. , Nandakvmar K.
Published: March 2009

The laminar mixed convection heat transfer of a non‐Newtonian fluid modelled by a power‐law constitutive equation is studied. The equations of motion subject to the Boussinesq approximation and an axially uniform heat flux and peripherally uniform wall temperature condition are discretized by finite difference approximation and are solved by the successive relaxation method. Dual solutions with two‐cell and four‐cell patterns have been observed in certain regions of the parameter space. The secondary flow caused by the buoyancy force has a shear thinning effect for pseudoplastic fluids. The Nusselt number, however, always increases with increasing Grashof number.
Air classification of rapeseed meal using the tervel separator
Authors: Diosady L. L. , Rubin L. J. , Tar C. G. , Etkin B.
Published: March 2009

The University of Toronto Tervel Separator was used to fractionate ground, defatted rapeseed meal into protein enriched, and high‐fibre products suitable for inclusion into food products and feed respectively. The meal was screened into fractions of a narrow range of particle size and classified at air speeds chosen to utilize as much of the collection area of the separator as possible. The meat‐rich and hull‐rich cuts were chosen arbitrarily, the cut point being a compromise between pure meat fraction and the greatest possible yield of the meat‐rich fraction. All meat‐rich samples had an increased protein content compared to the original oil‐free meal (43.1%). The 300/425 μm, 425/600 μm, and 600/850 μm meat‐rich fractions had a protein content (moisture‐, and oil‐free basis) of 54.4%, 55.6% and 49.5%, respectively. These meat‐rich fractions contained 28.7%, 20.9% and 15.3% of the protein present in the feed material for a total protein recovery of 64.9% in approximately 55% of the meat weight. The protein‐rich fraction is competitive with dehulled soya meal on the basis of protein content.
Anisole production by alkylation of phenol over ZSM5
Authors: Renavd M. , Chantal P. D. , Kaliaguine S.
Published: March 2009

The alkylation of phenol with methanol was performed in a microcatalytic reactor using the H‐ and Na‐forms of a ZSM5 zeolite. Conditions were found in which the selectivity of the O‐alkylation yielding anisole was as high as 80%. Some results are also reported for the alkylation of 2,4‐dimethylphenol.
Prediction of vapour pressure of aqueous solutions of single and mixed electrolytes
Authors: Kumar Anil , Patwardhan V. S.
Published: March 2009

A simple method is proposed for estimating the vapour pressures of aqueous single electrolyte solutions at 25°C. The method is based on a single empirical parameter, K. The treatment is extended to include different temperatures as well as solutions of mixed electrolytes. The estimation of vapour pressures in mixed solutions requires knowledge of the K values of constituent electrolytes and the vapour pressure of aqueous solutions of two reference electrolytes, viz. LiBr and NH4NO3 at 25°C. The calculated vapour pressures of single and mixed electrolyte solutions are in agreement with experimental data within 1.6% in general.
Correlations for prediction of diffusion in liquids
Authors: Siddiqi M. A. , Lucas K.
Published: March 2009

Based on an extensive experimental data collection (about 1925 points), empirical correlations for the estimation of binary liquid diffusion coefficients have been developed. The new correlations for organic mixtures and for aqueous solutions (including dissolved gases) require only well known and simple parameters like the viscosity of the solvent and the molar volumes of solute and solvent at the normal boiling point. They are shown to predict the limiting diffusion coefficients with the same or sometimes better accuracy than established correlations which make use of additional parameters. The concentration dependence of the mutual diffusion coefficients can be estimated from the knowledge of the two limiting diffusion coefficients and thermodynamic data. Established equations are investigated and classified for different groups of systems e.g. nonpolar + nonpolar, nonpolar + polar and polar + polar liquid mixtures.
Hydrodynamic investigations of gas–liquid contacting in a reciprocating plate column
Authors: VeljkoviC Vlada , Skala Dejan
Published: March 2009

The maximum pressure variation at the bottom of a reciprocating plate column of the Karr type was investigated in single phase liquid and two phase gas–liquid systems. In the gas–liquid system the gas hold‐up was also measured. The power consumption was calculated on the basis of the pressure variation at the bottom of the column.

It was shown that the power consumption depends on the vibration intensity, liquid density and geometrical characteristics of the column in a non‐gassed single phase liquid system and on the same factors, as well as gas hold‐up, in gas–liquid systems. Semiempirical correlations were derived for the purpose of predicting power consumption in both single and two phase systems in a reciprocating plate column.
Effect of time/temperature history on char reactivity
Authors: Katta Satyanarayana , Keairns Dale L.
Published: March 2009

The effect of heating rate, pyrolysis atmosphere, maximum heat treatment temperature (HTT) in different pyrolysis atmospheres used during char preparation, pressure of char preparation and holding time at maximum HTT on char reactivity was studied using Wyoming Sub‐C coal on a thermogravimetric analyzer (TGA). All these factors were found to have marked influence on char reactivity. Reactivity data are presented with rate as a function of carbon conversion and carbon conversion as a function of time or dimensionless time.
A novel curve fitting technique applied to drying curves
Authors: Rajan T.S. , Narayanaswamy S.
Published: March 2009

This Note discusses the problems associated with analysing drying curves during the falling rate period. Attempts at fitting the drying curves with purely exponential or polynomial relations to find empirical solutions have not always been satisfactory. In this context, a novel curve fitting technique is suggested. This technique, while ensuring the condition of maximum drying rate at the critical point, helps to depict the true trend of drying, agreeing very closely with experimental results. The technique uses an iterative computer program and yields a 99.9% fit as per chi‐square test.
Forced cycling of catalytic reactors: Number of cycles to reach cycle invariance
Authors: Lynch David T.
Published: March 2009

Pathologically slow convergence to cycle invariance during forced composition cycling of catalytic reactors is investigated using a mathematical model for carbon monoxide oxidation on platinum. It is shown that a very simple relationship quantitatively describes the details of this phenomenon.
Liquid holdup measurements in turbulent bed contactors by a tracer technique
Authors: Paterson A. H. J. , Clift R.
Published: March 2009

An experimental technique to eliminate the effects of sensor dynamics when a tracer is used to measure the hydrodynamics of a turbulent bed contactor is described. The resulting liquid holdup data are compared both with predictions from the pressure drop measurements and with the available correlations in the literature. The results show that the pressure drop method and Handl's (1976) equation under‐predict liquid holdup, while Rama et al.'s (1983) and Kito et al.'s (1978) equations over‐predict the results.
Kinetics of absorption of sulfur dioxide in dimethylaniline solution
Authors: Basu Ranjan K. , Dutta Binay K.
Published: March 2009

Absorption of sulfur dioxide accompanied by reversible reaction in dimethylaniline has been studied using a short falling‐film apparatus. Solutions of the amine in kerosene were used for this purpose. The effects of gas and liquid concentrations, contact time and temperature on the rate of absorption were investigated. Reaction equilibrium constant values were obtained at different temperatures from separate measurement of solubility of sulfur dioxide gas in kerosene as well as in dimethylaniline solutions. The heat of reaction was also calculated from these data. The absorption data could be satisfactorily interpreted by using the penetration theory of mass transfer with simultaneous pseudofirst order chemical reaction. The rate equations for the forward and reverse reactions were established.
Optimal temperature policies by distributed control for reactors with lhhw catalyst deactivation
Authors: Gonzalez‐Velasco Juan R. , Gutierrez‐Ortiz Miguel A. , Gutierrez‐Ortiz Jose I. , Gonzalez‐Marcos Jose A.
Published: March 2009

An approximate procedure for solving the problem of temperature optimal control distributed in both space and time coordinates is presented. It is applied to chemical reactors suffering from catalyst decay whose model is described by a complex second order partial differential equation deduced from LHHW kinetics. The proposed algorithm uses a finite‐difference approximation method to solve the state equation, and the control vector parametrization technique to obtain the optimal control. Numerical examples are computed and the results obtained show that distributed control reaches significantly higher production than lumped control.
Gasification of coal by a pilot flame in a modified fluidized bed
Authors: Chou Tse‐Chuan , Uang Yuh‐Ming
Published: March 2009

Coal is successfully gasified in the presence of a pilot flame in a modified fluidized bed. Except for the pilot flame, no external heat is required to operate this gasifier. The results showed that increasing the solid‐to‐air ratio in the feed increased the temperature and the products, carbon monoxide and hydrogen. About 95% of the volatile materials and 80% of the fixed carbon of the feed coal could be gasified by this pilot‐flame gasification method. The ash could be efficiently separated during gasification by a distributor within the dead‐zone collector of this gasifier.
Fischer‐tropsch synthesis in slurry phase: Effect of CO2 inhibition on performance of bubble column slurry reactors
Authors: Sanders Ernst , Deckwer Wolf‐Dieter
Published: March 2009

Fischer‐Tropsch Synthesis (FTS) was studied on a precipitated Fe/K catalyst in a bubble column slurry reactor (10 cm in diameter, suspension height ≤ 150 cm) with a perforated plate sparger. The rate data for syngas consumption obtained at low H2 to CO inlet ratios ( < 0.8) cannot be described by first order kinetics. However, a multicomponent model which considers rate inhibition by CO2 chemisorption gives an excellent description of the data. The optimized kinetic parameters are in agreement with recent findings from an autoclave unit. The multicomponent model and the kinetic parameters can be successfully applied to describe previous results from a bench‐scale pilot plant. The results indicate the importance of rate inhibition by CO2 if syngases of low H2 to CO ratio from advanced gasifiers are converted by FTS. Two‐stage processes with intermediate CO2 absorption are recommended.
Catalytic nitroxidation of para‐xylene over chromium oxide based catalysts
Authors: Zine S. , Sayari A. , Ghorbel A.
Published: March 2009

The synthesis of para‐tolunitrile (PTN) and terephthalonitrile (TPN) by reacting nitrogen monoxide with para‐xylene was studied in presence of three chromium oxide catalysts. The Cr2O3—Al2O3 catalyst was prepared under the form of aerogel or xerogel and shows excellent selectivities in nitriles along with good stability. However, the unsupported Cr2O3 catalyst showed much less performance and, in particular, produced no TPN. The beneficial action of alumina was explained in terms of stabilization of the Cr5+ species. Kinetic results seemed to indicate a redox‐type mechanism of the reaction. Moreover the PTN was shown to be an intermediate in TPN formation.
Measurement of solid concentration of a soluble compound in a saturated slurry
Authors: Rohani Sohrab , Paine Kevin
Published: March 2009

A method is proposed to measure the solid concentration of a soluble compound in a saturated slurry. The solution is gradually heated up while its temperature and monochromatic light transmittance are continuously being measured. The temperature at which the measured transmittance of the solution reaches a plateau is used to determine the solid concentration by using the solubility data of the solution. The method is successfully applied to the measurement of crystal concentration of a pure KCl slurry. The crystal concentration of two industrial slurries obtained from overflow of potash crystallizers have also been predicted. The technique has proven to be accurate in the absence of other soluble heat sensitive compounds.
Density of molten salt hydrates—experimental data and an empirical correlation
Authors: Sharma S. K. , Jotshi C. K. , Singh Amrao
Published: March 2009

The density of molten sodium salt hydrates which are suitable for energy storage applications has been determined by using a modified Sprengel pycnometer. The variation of density as a function of temperature shows linear behaviour. An empirical generalised correlation between reduced parameters of density and temperature is reported. This correlation predicts the density of salt hydrate melts of Na, Ca, Zn, Co, Ni, Cr and Fe ions from the density at the melting point, within an accuracy of ± 0.5 percent, for temperatures from the melting point to about 40 K above the melting point.
Prediction of steady‐state dispersion height in the disengaging section of an extraction column from batch settling data
Authors: Dalingaros W. , Jeelani S. A. K. , Hartland S.
Published: March 2009

The decay of a dense dispersion formed under calm conditions is given by

Experiments in a batch vessel with different liquid‐liquid systems and initial drop diameters show that the dimensionless constant K is equal to 26,000. This agrees with the value previously determined from the variation in steady‐state dispersion height with throughput in spray columns, the analogous equation being

The results can thus be used to predict the height of the dispersion formed in the disengaging section of extraction columns.
Heat transfer between very shallow fluidized beds and an immersed horizontal tube
Authors: Konrad K. , Huang H.
Published: March 2009

A new correlation is proposed for the heat transfer coefficient between an immersed horizontal tube and very shallow fluidized beds (static bed heights of 10‐40 mm). The correlation is based upon experimental data obtained in this work for a horizontal tube with an outside diameter of 13.1 mm, immersed in beds of spherical alumina particles with mean particle sizes of 335‐1261 microns. The maximum bed pressure drop was 92.5 mm water. The effects of tube elevation, static bed height and distributor design were investigated. Nine different distributors were used, with maximum pressure drops ranging from 3 to 800 mm water and open areas from 2.2 to 36%. A comparison between the proposed correlation and data reported in the literature showed an agreement of approximately ±10%.
Degradation of aqueous DEA solutions in a heat transfer tube
Authors: Chakma A. , Meisen A.
Published: March 2009

To study the degradation of aqueous diethanolamine (DEA) solutions in heat transfer equipment, DEA solutions were passed through a coiled heat transfer tube (2.032 mm ID, 3.175 mm OD, 4.8 m long) immersed in a constant temperature bath. The operating conditions were: DEA flow rate 0.011 to 0.0172 L/s, DEA concentration 20 to 40 wt%, DEA temperature 60 to 200°C, CO2 partial pressure 1.38 to 4.18 MPa. The degradation rate was found to increase with temperature, DEA concentration and CO2 partial pressure; it decreased slightly with solution flow rate. The degradation was accompanied by the formation of a fouling deposit. A simple mathematical model is presented for predicting DEA degradation.
Effect of surface resistance arising due to surfactant on gas absorption accompanied by a chemical reaction in a foam‐bed‐reactor
Authors: Biswas Jyotirmay , Asolekar Shyam R. , Kumar R.
Published: March 2009

On the basis of an idealized foam bed, a model to predict conversion in a foam‐bed‐reactor containing surfactant has been developed. The model takes into account the effect of surface resistance, arising due to the presence of a surface active agent, on gas absorption accompanied by a chemical reaction in a foam matrix. To verify the theory, experiments have been carried out in a semi‐batch foam‐bed‐reactor for the absorption of air‐carbon dioxide mixture in a foam of sodium hydroxide solution containing finite; concentrations of different surfactants. The surface resistance offered by the molecules of surfactant at the gas‐liquid interface reduces the mass transfer rates significantly. The proposed model predicts fairly well the experimentally found depletion values of sodium hydroxide.
Kinetics of the pyrolysis of utah tar sands
Authors: Lechner C. A. , Findley M. E. , Liapis A. I.
Published: March 2009

Utah tar sands have been pyrolyzed experimentally in a tubular furnace into a stream of nitrogen. Various condensate products have been collected and analyzed, and the pyrolyzed sands have been analyzed for coke and unreacted bitumen. The kinetics of the pyrolysis appeared to be second order under conditions of approximately constant temperature and in experiments with continuously changing temperatures. A lighter product with less sulfur, nitrogen, and arsenic was produced when more rapid heating rates were used. Other characteristics of the reaction and products are presented.
A chemical and thermal pretreatment process for the dewatering of fuel‐grade peat
Authors: Glass D. S. , Cooper D. G. , Sheppard J. D.
Published: March 2009

Using a batch heating system raw peat was heated to temperatures below 200°C before mechanical dewatering. Variations were made in heat up time, residence time and helding temperature. After heat treatment, dewatering could be further enhanced by the addition of chitosan, a polycationic biopolymer.
An empirical equation of state for gases and vapours
Authors: Sandri Robert
Published: March 2009

A simple pressure‐explicit equation of state for gases and vapours is presented which contains eight empirical constants in addition to the gas constant. It has been applied to four substances and reproduces their behaviour very well over a wide range of temperature (several hundred degrees), density (up to critical) and pressure (maximum 600 to 900 bar). For application above critical temperature only, a shorter version of the equation is presented for four more substances. Simple expressions are derived for entropy and internal energy.
Effect of acid strength distribution on de‐t‐butylation rate and catalyst fouling rate
Authors: Takahashi Takeshige , Kuramoto Kenji , Kai Takami , Tashiro Masashi
Published: March 2009

De‐t‐butylation of t‐butylbenzenes was carried out over a pyridine poisoned solid acidic catalyst to determine the effect of acid strength distribution on the reaction rate and catalyst fouling rate. The acid sites on the solid acidic catalyst were divided into three groups by their acid strength. Moderate acid sites, which were effective for the de‐t‐butylation but ineffective for the coke formation, were exclusively left on the catalyst surface by the partial poisoning.

It is found that the present modification of the catalyst is useful in preparing an acid catalyst without catalyst fouling by coke deposition.