bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trickle‐bed reactors: Effect of wetting geometry on overall effectiveness factor
Authors: Ring Z. E. , Missen R. W. 
Published: March 2009

AbstractCalculations 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

AbstractGlutathione 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

AbstractA 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

AbstractFirst 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractBased 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

AbstractThe 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

AbstractThe 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

AbstractThis 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.
Liquid holdup measurements in turbulent bed contactors by a tracer technique
Authors: Paterson A. H. J. , Clift R. 
Published: March 2009

AbstractAn 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

AbstractAbsorption 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

AbstractAn 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

AbstractCoal 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

AbstractFischer‐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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractTo 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

AbstractOn 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

AbstractUtah 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

AbstractUsing 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

AbstractA 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

AbstractDe‐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.