bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethanol production by extractive fermentation – solvent identification and prototype development
Authors: Kollerup Finn , Daugulis Andrew J. 
Published: March 2009

AbstractThe in situ removal and recovery of inhibitory fermentation products by solvent extraction has numerous beneficial effects (increased reaction rate, fermentation of concentrated feeds, decreased water usage, etc.) which have been confirmed on theoretical grounds. For the development of such an extractive fermentation process, the identification of solvents having desirable physical properties as well as complete biocompatibility with the microorganism is an absolute prerequisite, which, to this point, has not been adequately met. By means of a computer data base, we have systematically screened 1,361 solvents for their suitability for use in an extractive ethanol fermentation, and, through subsequent experimental evaluation of 70 of these solvents, have identified 19 as being appropriate for use in a continuous extractive fermentation process.Details of this screening procedure, and physico‐chemical data of the suitable extraction solvents are presented. A prototype extractive fermentation system, the first to employ a Continuous Stirred Tank Fermentor, is described. Results from mass transfer experiments in this prototype system, together with extractive fermentation experiments involving medium‐strength (ca. 150 g/L) glucose feeds are discussed.
Transient forced convection in laminar channel flow with stepwise variations of wall temperature
Authors: Cotta R. M. , Özişik M. N. 
Published: March 2009

AbstractTransient laminar forced convection of Newtonian fluids inside circular ducts and parallel‐plate channels subjected to stepwise variations of wall temperature is considered. Approximate analytical solutions are developed by making use of the generalized integral transform and the classical Laplace transform techniques. Higher order solutions are given for the case of a step change in wall temperature. A second‐order accurate finite‐difference solution is developed to assess the accuracy of the available approximate solutions. The Sign‐Count method is used to solve the resulting eigenvalue problems and determine as many eigenvalues and eigenfunctions as needed. Results are presented for the local Nusselt number, average fluid temperature and the wall heat flux over a wide range of the dimensionless axial coordinate.
Crystallization kinetics from transients of an MSMPR crystallizer
Authors: Tavare N. S. 
Published: March 2009

AbstractTransient population density curves from a continuous MSMPR crystallizer obtained in response to an application of external non‐homogeneous forcing functions (like changes in feed concentration or flowrate) were used to deduce simultaneously nucleation and growth kinetics. Several simplified parameter estimation procedures were examined using simulated experimental observations of population densities and gave consistent results. Results however obtained from an experiment performed in a small continuous MSMPR crystallizer for the precipitation of calcium oxalate showed apparent scatter in all the algorithms. Methods using transient population density information by themselves may be useful to determine and also to provide an independent check on the reliability of kinetic parameter estimates.
A modified “inside‐out” algorithm for simulation of multistage multicomponent separation processes using the UNIFAC group‐contribution method
Authors: Saeger Roland B. , Bishnoi P. R. 
Published: March 2009

AbstractA computational procedure using a modification of Boston and Sullivan's “inside‐out” multistage multicomponent separation algorithm (1974) is developed. In order to improve convergence behavior for problems involving mixtures with highly nonideal liquid phases, a two‐parameter model is used to describe liquid‐phase compositional effects upon the K‐factor. The quasi‐Newton methods of Mehra et al. (1983) and Nghiem (1983) are applied to solving various sets of solution variables in the proposed algorithm. Activity coefficients are calculated using the UNIQUAC activity‐coefficient model (1975) with parameters obtained from the UNIFAC group‐contribution method (1975). The computational procedure is applicable to distillation, absorption and reboiled‐absorption configurations. The proposed algorithm was implemented in a FORTRAN 77 program and tested on the Honeywell DPS 8/70M computer at the University of Calgary. Inclusion of the liquid‐phase model resulted in improved convergence behavior for nonideal systems in which the original “inside‐out” method failed to converge.
Effect of drop size and physical properties on dispersion height in the separating section of a liquid/liquid extraction column
Authors: Dalingaros W. , Hartland S. 
Published: March 2009

AbstractThe height of the dispersion formed in the separating section of an extraction column is given byH = K/g (σ/Δρg)1/2 I/ϕo (Qd/A)2Since calm conditions prevail the height of the sedimentation zone can be neglected and the dispersion is essentially dense‐packed. The effect of physical properties was investigated in a spray column using nine different liquid/liquid systems. A distributor divided into seven equal sectors enabled the effect of drop size and dispersed phase flow rate to be independently investigated.
Kinetics and reaction mechanism of hydrogen sulfide oxidation over activated carbon in the temperature range of 125–200°c
Authors: Ghosh Tushar K. , Tollefson Eric L. 
Published: March 2009

AbstractThe kinetics and reaction mechanism of the oxidation of hydrogen sulfide over activated carbon were studied in the temperature range 125–200°C. The heats of adsorption of oxygen and H2S were found to be 73.8 and 16.0 kJ/mol, respectively, in the above temperature range. The sorption constants and the reaction constant have been expressed as a function of temperature. The role of water in the oxidation reaction has been clarified. No evidence was found to show that sulfur catalyzes the oxidation reaction.
Velocity profiles at the exit of circular tubes
Authors: Leung S. K.‐L. , Esmail M. N. 
Published: March 2009

AbstractAn investigation has been carried out on velocity profiles of Newtonian liquids at the exit of circular tubes for Reynolds numbers from about 50 to 1000. A simple expression which asymptotically approaches a Poiseuille parabolic distribution for higher Reynolds numbers is obtained. Experimental measurements of extrudate swell ratios were used as criteria for convergence to the solution. Comparison with jet shapes from previous experimental and theoretical studies supports the obtained results. The work also illustrates a straightforward method for simplifying and solving the governing equations for laminar flows of thin liquid layers.
High shear jet‐mixers as two‐phase reactors: An application to the oxidation of phenol in aqueous media
Authors: Jaulin L. , Chornet E. 
Published: March 2009

AbstractJet‐mixers are known as devices capable of greatly enhancing the gas‐liquid interfacial areas. Their application to chemical reactions is discussed in this paper. The oxidation of phenols in aqueous media is considered.Rates of oxidation fifty times higher than those previously observed can be achieved through a jet‐mixer discharging a fine mist into the reactor side operating at plug flow regime. The presence of hydrogen peroxide accelerates the oxidation. Kinetic information is provided.
On interpreting ft product distribution data
Authors: Rice N. M. , Wojciechowski B. W. 
Published: March 2009

AbstractIt is shown that a CSTR is essential for the correct evaluation of kinetic parameters in the Fischer‐Tropsch (FT) synthesis. Furthermore, a rather complicated expression is required in order to extract the correct growth probability at low carbon number in cases where a “break” is observed in the Anderson‐Schulz‐Flory (ASF) distribution.It is shown that if product molecules can readsorb and continue to grow on a variety of locations where competing processes occur, the linearities of the ASF plot are preserved but the slopes of the plot no longer have a simple interpretation in terms of processes governing chain growth on the surface.Finally, results obtained using an integral Plug Flow Reactor (PFR) are shown to yield “growth probabilities” which have no fundamental significance and are a function of the level of conversion and of the input H2/CO ratio.
Coal slurry fuel technology
Authors: Papachristodoulou G. , Trass O. 
Published: March 2009

AbstractVolatile oil markets experienced in the seventies have promoted renewed interest in coal‐based fuel technologies. Coal‐slurry fuels have emerged as viable technical alternatives for oil and gas in utility and industrial boilers. Despite current low prices and the abundance of oil, concerns over its long‐term availability and price, as well as strategic considerations, make coal‐slurry technology attractive. Initially, coal‐slurry fuels were based on coal‐oil mixtures, now the emphasis is largely on coal‐water fuels.This review assesses the status of the relevant technology. It covers the preparation of coal‐slurry fuels, slurry properties, combustion characteristics, emissions, current applications and concludes with their future outlook.
A correlation for hydrogen solubility in alicyclic and aromatic solvents
Authors: Shaw J. M. 
Published: March 2009

AbstractA correlation for hydrogen solubility in aromatic, alicyclic, and heterocyclic hydrocarbon solvents is presented. This correlation, employing corresponding state theory, provides reliable estimates for hydrogen solubility, in simple and multicomponent solvents, over the temperature interval 0.45 ≤ Tr ≤ 0.97, and for pressures from 0.1 to 30.0 MPa. The correlation was found to have an average absolute error of 5.9% for 14 simple solvents, and 6.8% for 11 multicomponent solvents which include coal liquids and bitumen. Solvent specific coefficients are not employed, and the correlation is well suited for predicting hydrogen solubility in multicomponent ill defned solvents, or in simple solvents where experimental data are unavailable.
New analysis of non‐newtonian turbulent flowndashyield‐power‐law fluids
Authors: Thomas A. D. , Wilson K. C. 
Published: March 2009

AbstractThe writers' new analysis of non‐Newtonian turbulent flow is extended to the yield‐power‐law model. As the value of the exponent of the yield‐power law decreases from unity, the calculated friction factor begins by converging toward the Newtonian line at high velocity, then parallels it, and finally diverges downward. This prediction agrees with previously unexplained experimental results.
Effect of circulation rate on mass transfer in a forming drop
Authors: Guha D. K. , Vyarawalla F. , De P. 
Published: March 2009

AbstractThe prediction of mass transfer rate in an internally circulating drop forming in a continuous gaseous medium depends upon the residence time of a liquid element on the drop surface. A theoretical analysis has been made for the estimation of this contact time. The experimental results on comparison with the model show that the mass transfer rate is inversely proportional to the square‐root of the contact time as conceived by a modified penetration theory.
Film and penetration theories for a first‐order reaction in exothermic gas absorption
Authors: Chatterjee Siddharth G. , Altwicker Elmar R. 
Published: March 2009

AbstractFilm and penetration models for simultaneous heat and mass transfer are developed for the absorption of gas with a first‐order chemical reaction in the liquid phase with temperature‐dependent solubility and reaction rate coefficient. These two models represent two extreme conditions of interfacial temperature rise and gas solubility and they are compared with some previous models (Allan and Mann, 1979; Asai et al., 1985). The approximate analytical expressions of the penetration model of Asai et al. (1985) are in good agreement with the numerical results of this work. The results reveal that under many practical circumstances the gas‐liquid interfacial temperature may be several degrees Kelvin higher than the bulk liquid temperature. The degree of deviation of the enhancement factor from its isothermal value at the bulk liquid temperature depends on the degree of difference of a certain dimensionless activation energy group from zero, which confirms the previous finding of Asai et al. (1985).
Gas‐bubble hold‐up and axial dispersion coefficient of emulsion phases in fluidized beds
Authors: Kawase Y. , Moo‐Young M. 
Published: March 2009

AbstractA model for liquid mixing in a gas‐liquid bubble column is extended to predict gas‐bubble hold‐up and axial dispersion coefficient of emulsion phases in fluidized beds. Reasonable agreement is found between the proposed model which includes no adjustable parameter and the available experimental data and correlations.
Predicting collection efficiency of separation cyclones: A momentum analysis
Authors: Li P. M. , Lin S. , Vatistas G. H. 
Published: March 2009

AbstractThis paper uses a quantity of moment of momentum to combine various parameters interacting in a separation cyclone. Due to construction features and flow characteristics, the swirl flow in the cyclone is essentially frictionless and, hence, the incoming momentums of both the transporting fluid and suspended particles are conserved. Visualizing a 50%‐separation screen installed, and employing a stability‐radius theory, the momentums are expressed in terms of distributed masses in the cyclone. Further, in conjunction with the continuity equation, the collection efficiency is determined. The predicted value differs from the experimental one by about 6%.
On the particle terminal velocity in a gas‐liquid medium with liquid as the continuous phase
Authors: Jean Rong‐Her , Fan Liang‐Shih 
Published: March 2009

AbstractA mechanistic model was developed to describe the terminal velocity of spherical particles in a gas‐liquid medium with liquid as the continuous phase. The model was established based on the momentum balance of a single particle taking into consideration the drag and buoyancy forces due to the liquid phase and the bubble‐wake and particle interaction. The bubble‐wake and particle interaction coefficient was shown to be a function of the particle properties only. A comparison of the particle terminal velocity between the model prediction and experimental data obtained in this study was also made over a wide range of particle size and gas velocity.
Overall effectiveness factor of heterogeneous‐homogeneous chain reactions with one limited species in a catalytic slurry reactor
Authors: Hwang Bing Joe , Chou Tse‐Chuan 
Published: March 2009

AbstractThe analysis of the overall effectiveness factor for the reaction system involving heterogeneous‐homogeneous chain reactions at low concentration of one species is studied. A more general theoretical analysis for estimating the overall effectiveness factor of reaction systems which can be a heterogeneous‐homogeneous chain reaction system at low concentration of one species in a slurry reactor is presented, incorporating all the transport parameters. The concepts of overall effectiveness factors for reactions have been extended from the traditional heterogeneous reaction system to the heterogeneous‐homogeneous chain reaction system. The effects of reaction mechanism and kinetic models on the overall effectiveness factor are also proposed. Comparisons of the overall effectiveness factor for a slurry reactor with or without considering the reaction mechanism are also obtained.
Vapor‐liquid equilibrium of the binary mixtures CnH2n + 1(OH) (n = 2,3,4) + Propyl Ethanoate and + Ethyl Propanoate
Authors: Ortega J. , Ocon J. , Pena J. A. , De Alfonso C. , Paz‐Andrade M. I. , Fernandez J. 
Published: March 2009

AbstractThe compositions of the vapor‐liquid equilibria have been obtained in a small‐capacity recirculating still for the binary systems comprised of ethanol, propan‐l‐ol and butan‐l‐ol with propyl ethanoate and ethyl propanoate at a constant pressure of 101.32 ± 0.07 kPa. The experimental data were correlated with suitable equations and the azeotropes and their minimum boiling temperatures found were: ethanol + propyl ethanoate (x = y = 0.923; T = 351.5 K), propan‐l‐ol + propyl ethanoate (x = y = 0.610; T = 361.7 K), ethanol + ethyl propanoate (x = y = 0.875; T = 350.9 K) and propan‐l‐ol + ethyl propanoate (x = y = 0.534; T = 366.2 K).
Mass transfer at erosion‐corrosion roughened surfaces
Authors: Postlethwaite J. , Lotz U. 
Published: March 2009

AbstractRates of pipewall oxygen mass transfer in a 39 mm ID vertical pipe carrying an aqueous slurry containing 20 vol% 30‐50 mesh sand have been determined electrochemically with twin in‐line flow cells, one containing a mild steel specimen previously roughened by erosion‐corrosion and the other a smooth specimen. Measurements were also made without the solids present.The three‐dimensional rough surface, with roughness height approximately 0.2 mm, and pitch/height in the range 5 to 10, resulted in mass transfer enhancement up to 100%, in both the slurry and the solution, with the maximum effect occurring at the dimensionless roughness height e+ ≈︁ 30.
Liquefaction of lignocellulosics in model solvents: Creosote oil and ethylene glycol
Authors: Vanasse C. , Chornet E. , Overend R. P. 
Published: March 2009

AbstractThe UDES‐S liquefaction process treats concentrated pastes (20% of initially present solids) of finely divided (dp < 0.5 mm) lignocellulosics in organo‐solvolytic media by means of thermo‐mechanical action in homogenizing valves.The work described in this paper was carried out with Populus Deltoides in a process development unit capable of processing up to 4 kg of dry wood per hour. The model solvents used were creosote oil and ethylene glycol, which represent solvents that could be derived from the process or its products. Liquefaction mechanisms depend upon the solvent‐substrate interaction: with creosote oil, pyrolysis mechanisms predominate and lead to integral liquefaction of the wood while with ethylene glycol only fractional liquefaction was possible, apparently as a result of a complex formation between ethylene glycol and cellulose which protects the chain polymeric from being solubilized.
Vapor‐liquid equilibrium, excess gibbs energy and excess enthalpy of 1, 3 dioxolane‐methylcyclohexane at t = 313.15 k
Authors: Castellari Carlo , Francesconi Romolo , Comelli Fabio 
Published: March 2009

AbstractData on vapor‐liquid equilibrium and enthalpy of mixing HE are, obtained for the mixture 1, 3 dioxolane‐methylcyclohexane at 313.15 K (40.0°C). Correlation of the data is given by using Redlich‐Kister expressions and the excess functions GE = RT(X1 In γ1 + X2 In γ2) and TSE = HE ‐ GE are thereby calculated. A comparison is made between this mixture and those formed by 1, 3 dioxolane with cyclohexanol and cyclohexanone.
Mass transfer characteristics in a gas‐liquid reciprocating plate column. I. Liquid phase volumetric mass transfer coefficient
Authors: Skala Dejan , Veljković Vlada 
Published: March 2009

AbstractIn a series of two papers the results of investigating the mass transfer characteristics of two gas‐liquid reciprocating plate columns of the Karr type by different methods are presented. The subject of the first part is a study of the liquid phase volumetric mass transfer coefficient, kLa, while the second part deals with the interfacial area.The volumetric coefficient kLa was investigated using the sulphite method, the pure physical absorption of oxygen, and a dynamic method under culture conditions, the second of these three methods being the most favorable.Very good agreement among these methods was found. Generally, kLa increased with increasing vibration intensity, superficial gas velocity, and the number of perforated plates. Liquid‐phase properties appeared to affect kLa only slightly. The coefficient kLa was correlated in terms of the maximum power consumption and the superficial gas velocity:
The plasma production of ultrafine silica particles
Authors: Gans I. , Gauvin W. H. 
Published: March 2009

AbstractA process for producing ultrafine silica particles incorporating a plasma transferred‐arc reactor of novel design (Plas‐macan) was developed. The process consisted of vapourizing small particles of sand (99.5% SiO2) which subsequently dissociated into SiO gas and oxygen in the presence of an argon plasma. Quenching of this gaseous mixture reconstituted SiO2 in the form of an aerosol. Various reacting media (H2, steam or NH3) were tested to assist the dissociation and to enhance the properties of the particles produced. The quenching of the particles was effected with oxygen or steam. A feedrate of 1.3 kg/h SiO2 and a power of 30 kW for plasma generation were used throughout the work. Amorphous silica particles, average 0.07 μm in diameter, were produced.
The effects of ferrous iron, dissolved oxygen, and inert solids concentrations on the growth of thiobacillus ferrooxidans
Authors: Liu M. S. , Branion R. M. R. , Duncan D. W. 
Published: March 2009

AbstractThe effects of suspended, inert solids concentration, ferrous iron concentration and dissolved oxygen concentration on the kinetics of iron oxidation by Thiobucillus ferrooxidans are reported. It is shown that the maximum specific growth rate for this organism, oxidizing ferrous iron, is of the order of 0.1 h−1. Competitive inhibition by femc iron is demonstrated. The dissolved oxygen concentration below which the bacteria will not grow is 0.20 mg/L. The dissolved oxygen concentration below which O2 availability is limiting is around 0.29‐0.7 mg/L. 10.4 millimols of CO2 are fixed by the bacteria per mol of ferrous iron oxidized. 0.0185 mg of bacterial carbon are generated per mg of O2 consumed. Comparative mass transfer rates for O2 and CO2 are discussed. Oxidation rates decreased significantly in shake flasks as suspended solids concentrations rose above 0.5%, whereas in stirred tanks solids concentrations up to 15% had little effect on oxidation rate.
Optimal temperature policies for catalytic transport reactors under periodic operation
Authors: Sivakumar S. , Chidambaram M. , Shankar H. S. 
Published: March 2009

AbstractThe influence of inlet gas concentration cycling on the optimal temperature policy of catalytic transport reactors is studied theoretically. The model considered is based on plug flow of gas and catalyst particles with negligible interand intra‐particle diffusional resistances and concentration dependent deactivation kinetics. To utilise the concentration of the reactant and the activity of the deactivating catalyst fully a proper temperature sequence along the reactor is needed. Thus, a general optimal temperature policy using the continuous minimum principle is derived for the reactor under periodic operation. The model equations are solved analytically for gas concentration, activity and temperature profiles. Resonance behaviour (maximum in conversion with pulse width) is obtained using the optimal temperature policy for certain sets of parameters. The effects of activation energy groups, reaction and deactivation constant groups and inlet temperature on the optimal temperature policy under periodic operation are evaluated. In all cases an improvement in conversion with the optimal temperature policy under periodic operation over that with an isothermal policy under periodic operation is obtained. A suboptimal policy, comprising constant temperature over different reactor sections, which is useful for implementation purposes is also discussed.