bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation of solubility of hydrogen in hydrocarbon solvents
Authors: Sebastian H. M. , Lin H. M. , Chao K. C. 
Published: June 2004

AbstractA correlation is developed for the solubility of hydrogen in hydrocarbon solvents at temperatures from 310 to 700 K and pressures to 30 MPa (300 bar). The fugacity of dissolved hydrogen at zero pressure is correlated as a function of solubility parameter and temperature. The high‐pressure fugacity is obtained upon applying a Poynting factor for which the required partial molal volume of hydrogen is also correlated in terms of solubility parameter and temperature. The Henry constant of hydrogen is included in the correlation. The correlated results are compared with experimental data for 22 systems of binary and ternary solutions and five narrow‐boiling cuts of coal liquids. The overall average absolute deviation for all systems studied is approximately 6%.
Measurement of mass flux in two‐phase flow using combinations of pitot tubes and gamma densitometers
Authors: Hau K‐F F‐L , Banerjee S. 
Published: June 2004

AbstractNew experimental data indicate that mass flux in cocurrent gas‐liquid flows may be determined by the use of Pitot tubes in conjunction with a local mixture density measurement technique. The data were taken over a wide range of flow regimes in a horizontal pipe and included separated patterns such as stratified and annular flows. Local mixture densities were obtained by a computer‐assisted algebraic reconstruction technique that used chordal average densities measured by traversing gamma beam attenuation.The results extend the applicability of this mass flux measurement technique well beyond the relatively homogeneous, high‐pressure, steam‐water flow situations originally studied by Banerjee and Nguyen (1977).
Efficiency of mixing from data on fast reactions in multi‐jet reactors and stirred tanks
Authors: Ottino J. M. 
Published: June 2004

AbstractSome fluid mechanical information concerning mixing generation in complex flow fields can be obtained from conversion data of fast chemical reactions. Computation of such information and averages required in the procedure are presented here. Complex turbulent flow fields present deterministic‐like behavior when analyzed in average sense with regard to mixing generation.
A review of process synthesis
Authors: Nishida Naonori , Stephanopoulos George , Westerberg A. W. 
Published: June 2004

AbstractProcess synthesis is the step in design where the chemical engineer selects the component parts and how to interconnect them to create his flowsheet. This paper reviews the rapidly growing process synthesis literature of over 190 articles, almost all of which have been produced in the last decade.The paper first introduces the nature of the synthesis problem and outlines the variety of approaches which have appeared to solve aspects of it. The problems include developing a representation, a means to evaluate alternatives, and a strategy to search the almost infinitely large space of possible alternatives. As the article demonstrates, effective solutions are very dependent on the nature of the synthesis problem being addressed.The article covers in detail the following five synthesis topics: chemical reaction paths, separation systems, heat exchanger networks, complete flowsheets, and control systems. Readily apparent are the development of industrially significant insights to aid in the design of heat exchanger networks. Reasonable progress exists in the synthesis of separation systems based on nearly ideal distillation technology and in the development of computer aids by chemists for reaction path synthesis leading to desired complex organic molecules. More work is needed for the remaining areas to become industrially significant.
Drag force measurement of single spherical collectors with deposited particles
Authors: Pendse Hemant , Tien Chi , Turian R. M. 
Published: June 2004

AbstractThe hydrodynamic drag force in a uniform flow field acting on a spherical body with small particles attached to its surface was determined experimentally. The experimental data are used to substantiate the approximate force expressions derived from available theories for several types of collector‐particle geometries. Procedures for applying these results to the prediction of the pressure drop across a filter bed with various degrees of particle deposition are also developed.
Pressure fluctuations in a fluidized bed
Authors: Fan L. T. , Ho Tho‐Ching , Hiraoka S. , Walawender W. P. 
Published: June 2004

AbstractAn on‐line statistical study of the pressure fluctuations in fluidized beds was conducted by using pressure transducers, a correlation and probability analyzer and a Fourier transform analyzer. The causes of the fluctuations were explored, and the effects of the gas velocity, bed height, particle size and distributor design on the major frequency and amplitude of the fluctuations were investigated. The results indicate that the motion of bubbles appears to be the major cause of the pressure fluctuations in the upper portion of a fluidized bed. In the lower portion, the combined effects of the formation of large bubbles in the middle portion of the bed, the formation of small bubbles near the distributor, and the jet flow immediately above the distributor appear to be the major causes of pressure fluctuations.
Bacterial film growth in adsorbent surfaces
Authors: Andrews G. F. , Tien Chi 
Published: June 2004

AbstractSimultaneous biological and activated‐carbon treatment of organic wastewaters appears promising. The effects of bacterial film growth on adsorbent particles is investigated by laboratory work and mathematical modelling. Regeneration of the adsorbent due to film growth does occur, but faster than predicted. The discrepancy reflects uncertainty about the structure of bacterial films.
Minimum reflux conditions, part I: Theory
Authors: Nandakumar K. , Andres R. P. 
Published: June 2004

AbstractThis paper presents a new formulation of the infinite plate or minimum reflux limit of a multicomponent distillation column. Based on this model, two new calculation methods are developed. The first is a short‐cut method which extends Underwood's classic minimum reflux treatment to variable molar overflow situations. The second is a rigorous method which is similar to a multicomponent flash calculation and represents a significant computational advance over other rigorous methods.
Steady‐State uniqueness and multiplicity of nonadiabatic gas‐liquid CSTRs, part I: Second‐order reaction model
Authors: Huang D. T.‐J. , Varma Arvind 
Published: June 2004

AbstractSteady‐state behavior of a non‐adiabatic gas‐liquid CSTR is classified applying a second‐order reaction model without any limitation on the reaction regime. Uniqueness and multiplicity regions are determined in the parameter space of reactivity versus liquid residence time, with the ignition and extinction points explicitly shown. An isola with five steady states is found possible for the adiabatic reactor; however, even a small heat loss reduces the number of steady states to three.
II: Discrimination among rival reaction models
Authors: Huang D. T.‐J. , Varma Arvind 
Published: June 2004

AbstractThe discrimination of the fast second‐order, pseudo‐first‐order and fast pseudo‐first‐order reaction models on the basis of the second‐order reaction model justifies the use of the pseudo‐first‐order model in the prediction of the multiplicity regions. The use of the fast second‐order reaction model leads to a certain pitfall regarding uniqueness and multiplicity. Finally, the use of the fast pseudo‐first‐order reaction model is justifiable not only because of the fair agreement between the multiplicity regions predicted by this model and the second‐order model but also because of the analyticity of the uniqueness and multiplicity regions obtained by this model.
An approximate approach to design and analysis of fixed‐bed catalytic reactors
Authors: Lee Hong H. 
Published: June 2004

AbstractAn approximate approach is proposed for the design and analysis of fixed‐bed catalytic reactors in which the intraphase diffusion is important. This approach makes it possible to transform the design and analysis problem of nonisothermal reactors with inter‐ and intraphase mass and heat transfer resistance into one of simply integrating a single equation with respect to concentration. This transformation is applicable to general from of kinetics. Exceptions are reaction rate forms that can exhibit empirical or approximate negative order behavior. The transformation is based on a generalized effectiveness factor or a reactor point effectiveness factor. While the design and analysis of two‐dimensional reactors requires simultaneous solution of conservation equations for mass and heat which are transformed into the equivalents of homogeneous reactors, the problem of one‐dimensional reactors with axial dispersion involves simple integration of a single mass conservation equation.
Effect of fluid drag on low reynolds number discharge of solids from a circular orifice
Authors: Altenkirch R. A. , Eichhorn Roger 
Published: June 2004

AbstractA dimensionless solids flowrate for discharge from an orifice in the bottom of a containing vessel is shown to be a function of a parameter that measures the importance of fluid drag to particle inertia. The analysis assumes a linear relation between presure gradient and slip velocity and compares favorably to experiment within its supposed region of applicability for three experimental situations: the self‐induced, air‐impeded discharge of fine particles from a conical hopper; the discharge of particles from a sealed egg‐timer‐like vessel; and the air‐assisted discharge of particles through an orifice.
Diffusivity and solubility of carbondioxide in diluted polymer solutions
Authors: Lohse M. , Alper E. , Quicker G. , Deckwer W.‐D. 
Published: June 2004

AbstractDiffusion coefficients of CO2 in aqueous Newtonian solutions of polyvinyl alcohol and polyethylene glycol with molecular weights varying from 1500 to 100,000 were obtained from absorption rate measurements in a wetted‐wall column and the CO2 solubilities determined independently. The exponent A of the diffusivity‐viscosity relation is found to be a strong function of the molecular weight of the applied polymer. The data suggest the following correlation:

which indicates that the exponent may vary from 0.04 to 0.4 for the solutions studied.
Slow migration of a gas bubble in a thermal gradient
Authors: Subramanian R. S. 
Published: June 2004

AbstractThe steady migration velocity of a gas bubble placed in a liquid with a linear temperature field in the absence of gravity is obtained for small Marangoni Numbers using a matched asymptotic expansion procedure for solving the governing equations. A result good to 0(N) is obtained, and in the limiting case of zero Marangoni Number, the results of Young, Goldstein and Block are recovered.
Analysis of control‐output interactions in dynamic systems
Authors: Tung L. S. , Edgar T. F. 
Published: June 2004

AbstractA general theory for examining the dynamic as well as static interactions among inputs and outputs in a multivariable control system has been developed. Both state space and frequency domain approaches are used, and at steady state the interaction equations assume the same form as the relative gain array developed by Bristol. Implications of selecting input‐output pairings with regard to steady state vs. dynamic consideration are discussed. The application of the method of analysis to a distillation column control system is presented.
Diffusion effects in initiator decomposition in highly viscous and macromolecular solutions
Authors: Kulkarni M. G. , Mashelkar R. A. 
Published: June 2004

AbstractDiffusional limitations in single bond and multibond initiators were experimentally investigated. The concept of “microviscosity” was proposed to account for diffusional resistance in different media. This was then used to obtain a unified correlation of the diffusional phenomena regardless of the nature of viscogen. Parameters related to the kinetic and diffusive processes were evaluated and interpreted giving clear fundamental and pragmatic implications of the findings.
Exclusive tear sets for flowsheets
Authors: Motard Rodolphe L. , Westerberg Arthur W. 
Published: June 2004

AbstractA new implicit enumeration algorithm locates the minimum weighted tear sets among those which belong to the nonredundant families of Upadhye and Grens (1975). Theoretical developments support the algorithm and give a new insight relating nonredundancy to the tearing of unit loops in a flowsheet. If all loops can be torn exactly one time, the nonredundant family is unique and a member of it is trivial to find. If not possible, two or more nonredundant families exist and the above algorithm discerns among them, picking a tear set which minimizes the maximum number of times any unit loop is torn.
Exact calculation methods for systems of interlinked columns. Part I: Separation of binary heterogeneous azeotropes
Authors: Hsu Hsien , Tierney J. W. 
Published: June 2004

AbstractA mathematical model and iterative correction algorithm are described for the exact solution of separation systems which contain interlinked columns in which some stages have two liquid phases and others have a vapor and liquid phase. The correction algorithm is based on Newton's method and provides for simultaneous correction of all iteration variables. The derivatives are calculated analytically from the model equations. The separation of a binary mixture which forms a heterogeneous azeotrope is analyzed. Modifications to the correction algorithm which provide for fixed condenser temperature and fixed product flows are described. The separation of butanol and water is used to illustrate the method.
Asymptotic expansions for the description of gas bubble dissolution and growth
Authors: Subramanian R. S. , Weinberg M. C. 
Published: June 2004

AbstractA new asymptotic expansion is presented to describe the dissolution or growth of an isolated, stationary gas bubble in a liquid. With the exception of long times, bubble radii calculated via this expansion are in excellent agreement with values obtained by numerical methods over a wide range of gas under(super)‐saturations.
Esterification of butanol in a two‐phase liquid‐liquid system. PART I: Quaternary phase equilibria studies
Authors: Al‐Saadi A. N. , Jeffreys G. V. 
Published: June 2004

AbstractThe phase equilibria of the systems are discussed:

n‐butanol‐acetic acid‐water and n‐heptane
Water‐acetic acid‐benzene and carbon tetrachloride
Water‐methanol‐p.cresol and methyl naphthalene have been studied and a correlating procedure has been developed that utilizes binary and ternary experimental data to predict the composition of the quaternary equilibrium mixtures. Allowance is made for the different salting effects and the agreement between the experimental and predicted quaternary data is in all cases very good.
An analytical Carnahan‐Starling‐van der Waals model for solubility of hydrocarbon solids in supercritical fluids
Authors: Johnston K. P. , Eckert C. A. 
Published: June 2004

AbstractData have been taken by a new flow technique for the solubility of nonpolar hydrocarbons in nonpolar supercritical fluids. These results for molecularly simple molecules provide a basis for the analytical representation of such systems by relatively simple equations of state.
Measurement of effective diffusivity from effluent concentration of a flow through diffusion cell
Authors: Frost A. C. 
Published: June 2004

AbstractThe overall effective diffusion coefficient for 3.3 mm extrudates of 5A Zeolite and CO2/N2 at 292°K and 142 kN/m2 was measured in a continually purged, well mixed, constant volume diffusion cell. The change of CO2 concentration in the effluent stream resulting from a step change in the influent stream was used with appropriate parameters in the analytical solution to calculate diffusion coefficients for the 0 to 0.1 vol. % and 0.1 to 1.0 vol. % CO2 concentration ranges.
Characterization and analysis of continuous recycle systems: Part II. Cascade
Authors: Mann Uzi , Rubinovitch Michael 
Published: June 2004

AbstractA general analysis of a cascade of identical recycle units is presented by means of studying the fluid history inside the system. This is an extension of Part I (Mann et al., 1979) in which a single recycle unit was analyzed. The history of a fluid element is expressed in terms of the number of cycles it completes, the time it resides in the system and the total time it resides in a specific section of the system—all are random variables. Concepts from probability theory and stochastic processes are used to derive the number of cycles distribution (NCD), residence time distribution (RTD) and various total regional residence time distributions (TRRTDs) as well as their means and variances. Expressions for the joint distributions of pairs of these random variables are also derived as well as explicit expressions for their covariances and correlation coefficients. Two applications of the results are illustrated: one in analyzing a continuous spouted‐bed coating unit and the second in using the cascade as a flexible, physically based multi‐parameter flow model.
Multistage membrane separation processes for the continuous fractionation of solutes having similar permeabilities
Authors: Noda Isao , Gryte Carl C. 
Published: June 2004

AbstractA new cascade configuration for the continuous membrane fractionation of solutes having similar permeabilities is proposed. In this scheme, solute selectivity is amplified by combining a concentrator and several mass exchangers (e.g., a reverse osmosis unit and hollow fiber dialyzers) to achieve a desired degree of separation. Separation efficiency of the new cascade is compared with that of a conventional counter‐current cascade.
Modeling of three phase reactors: A case of oxydesulfurization of coal
Authors: Joshi J. B. , Abichandani J. S. , Shah Y. T. , Ruether J. A. , Ritz H. J. 
Published: June 2004

AbstractMathematical models have been developed for the design of bubble column slurry reactors, wherein the solids take part in the reaction and follow the shrinking core model. The cases of liquid film control, ash diffusion control, and chemical reaction control have been analyzed. Experiments were performed in a 22.2 mm i.d. continuous cocurrent bubble column slurry reactor for the removal of pyritic sulfur by oxidation from aqueous slurries of Upper Freeport, Lower Freeport, Kentucky No. 9, and Pittsburgh seam coals, in the temperature range of 430‐480°K at 6.8 MPa total pressure. The theoretical predictions are found to be in good agreement with experimental results.
Hydrodeoxygenation of dibenzofuran and related compounds
Authors: Krishnamurthy S. , Panvelker S. , Shah Y. T. 
Published: June 2004

AbstractThe catalytic hydrodeoxygenation (HDO) of dibenzofuran was examined on a presulfided NiMo/γAl2O3 catalyst. Based on the reaction intermediates identified in the present study a reaction network for the removal of oxygen from dibenzofuran has been established. In view of the failure to detect certain key reaction intermediates an approximate network has been proposed for kinetic analysis. Using the approximate network the effects of temperature in the range 616–649K, hydrogen pressure in the range 6.89–13.78 MPa and initial concentration of dibenzofuran in the range 9.78 × 10−5 − 21.39 × 10−5 g mol/g oil were examined upon the individual steps.The removal of oxygen from dibenzofuran under the above conditions proceeded via direct oxygen extrusion without hydrogenation of the adjacent benzene rings as well through the formation of hydrogenated intermediates, with the catalyst showing selectivity towards the latter mode of oxygen removal. Presulfiding the catalyst as well as addition of CS2, to maintain a partial pressure of H2S during the reaction, enhanced the activity of the catalyst. The effect of initial concentration of dibenzofuran indicated a retarding influence on its HDO, possibly due to the formation of refractory reaction intermediates.The HDO of two key reaction intermediates in the network for dibenzofuran, namely, o‐phenyl phenol and o‐cyclohexyl phenol, was also examined on a presulfided NiMo/γAl2O3 catalyst to establish the reaction network for dibenzofuran. The primary mode of oxygen removal from both the phenols, in the temperature range of 561–644K and 10.34 MPa hydrogen pressure, was through the formation of highly reactive hydrogenated intermediates. All the primary reactions for o‐phenyl phenol were catalytic in nature, whereas, o‐cyclohexyl phenol was found to crack to phenol and cyclohexane even under purely thermal conditions. The rates of decomposition of the above phenols were fairly rapid and highly temperature sensitive, thereby explaining their absence in the reaction products of dibenzofuran.
Model‐based analysis of data from countercurrent liquid‐liquid extraction processes
Authors: Spencer J. L. , Steiner Ladislav , Hartland Stanley 
Published: June 2004

AbstractAn efficient iterative method for solving the equations which describe the steady state of a staged countercurrent extraction process is described. The equations include the effects of backmixing, and apply to an arbitrary number of solutes, to nonlinear equilibrium relations, and to variable net phase flow rates (and thus to partially miscible solvents). The solution procedure, based on partial linearization of the equations, is related to and extends the method of Ricker et al. (1980).This solution procedure has been used, in conjunction with nonlinear regression methods, to investigate problems related to the determination of parameters by analyzing steady state data. The simultaneous determination of several parameters, including mass transfer coefficients, backmixing coefficients, and equilibrium constants, is shown to be possible. The accuracy with which the parameters can be estimated depends, however, on many factors, including the number and location of the sampling points, the intensity of the backmixing, and the extent to which equilibrium is approached in the column.
Effect of H2O2 on homogeneous gas phase NO reduction reaction with NH3
Authors: Azuhata S. , Akimoto H. , Hishinuma Y. 
Published: June 2004

AbstractTo study the effect of H2O2 on NO reduction with NH3, the homogeneous gas phase reaction of NH3NOH2O2O2 was investigated in a Pyrex flow reactor over the temperature range from 500°C to 600°C under one atmospheric pressure. H2O2 accelerated the NO reduction by NH3 and caused it to be induced at a temperature of 500°C. In the absence of O2, NOx reduction ratio of more than 90% was obtained for NH3/NO5 and H2O2/NO1 at 550°C. In the presence of O2 or an excess of H2O2, two side reactions, which cause the NOx reduction ratio to decrease, occur.One of the side reactions is NO oxidation with H2O2. It was found experimentally that NO2 inhibited NO reduction and that H2O2 was an NO oxidizing agent, as well as an NH3 decomposing agent. The other side reaction was the formation of NO and NO2, which resulted from the oxidation of NH3 with O2. Under the conditions of our experiments, the amount of O2 in our reaction system was extremely high compared to the amounts of NO, NH3 and H2O2 in the system. Thus NOx was assumed to be produced by the oxidation of the NO reducing radicals, which were produced by the reaction of NH3 with H2O2.
Solution of stiff ordinary differential equations by decomposition and orthogonal collocation
Authors: Burka M. K. 
Published: June 2004

AbstractA fast and accurate method was developed for the integration of large sparse systems of stiff initial value ordinary differential equations. The system is ordered, decoupled and, if necessary, torn into subsystems (also called blocks) which are then solved by orthogonal collocation on finite elements. The size of these elements, or steps, is different for each subsystem and is a function of the stiffness of the set of equations constituting the subsystem. The steps are overlapped for maximum computational efficiency.