bluuebunny/crossref_metadata_2025_split huggingface dataset:
On‐line gain identification of flow processes with application to adaptive pH control
Authors: Gupta Surendra R. , Coughanowr Donald R. 
Published: June 2004

AbstractA simple and practical method is presented for the control of first‐order flow processes with time varying gain and a pure delay in the measurement of the control variable. It involves on‐line identification of the process gain and a subsequent adjustment of the controller parameter. The method is well suited for applications in the chemical process industries where high frequency fluctuations in the process gain are not generally expected. It is tested on a computer simulated process as well as experimentally by application to a continuous stirred‐tank neutralization process involving pH control, where buffer concentration in the feed varies with time. There is a potential for the application of this method to an industrial process such as wastewater treatment.
Vapor‐liquid equilibrium for salt containing systems: Correlation of binary solvent data and prediction of behavior in multicomponent solvents
Authors: Rousseau R. W. , Boone J. E. 
Published: June 2004

AbstractWhen salts or electrolytes are encountered in the design of separation equipment, the effects of these electrolytes on the vapor‐liquid equilibrium behavior of nonelectrolytes are often neglected. This is the case because there has not been a method for the correlation of data for salt containing systems which can be used for varying salt and solvent compositions. Boone, Rousseau, and Schoenborn (1976) proposed a method for correlating data from binary solvent‐salt systems which are not restricted in this manner. This work proposes an extension that correlates phase equilibrium behavior using the Prausnitz UNIQUAC equation, which can be used for systems having regions of immiscibility. In addition, the model used for binary solvent systems is extended to multisolvent salt systems, and it is shown that vapor‐liquid equilibrium data for these systems can be predicted from data on binary solvent‐salt systems.
Underground coal gasification
Authors: Gregg D. W. , Edgar T. F. 
Published: June 2004

AbstractUnderground coal gasification (UCG) is a method whereby the mining and conversion of coal are accomplished in a single step. Many field tests of UCG have been operated worldwide since the 1930's with varying degrees of success; based on this experience (especially in the USSR and United States), a field design which is applicable to a wide range of geological conditions and coal properties has evolved. This review discusses the rationale of this design and provides a physicochemical interpretation for the operation of a UCG system. Pertinent field and laboratory results as well as formal mathematical models of an in situ gasifier are evaluated as part of the analysis.
The mechanisms of transfer of hydrophobic coated mineral matter particles from a hydrocarbon to an aqueous phase
Authors: Prudich Michael E. , Henry Joseph D. 
Published: June 2004

AbstractA solid/liquid separation process based on the transfer of hydrophobic coated mineral particles from a hydrocarbon to an aqueous phase is described. This process could be used, for example, to remove mineral matter from coal derived liquids in order to meet fuel specifications. A model system which involves hydrophobic, asphaltic, coated mineral matter particles in a model liquid, xylene, was used in conjunction with the mechanistic studies. The mineral matter distribution coefficient to the aqueous phase decreases rather than increases with time in batch experiments. Five asymptotic models based on the fate of the surface active chemical at long time are investigated. Included were adsorption on the mineral matter particle, adsorption at the oil/water interface, distribution of the surfactant to the aqueous phase, complete detergency, and partial detergency. Experimental data on the influence of surfactant concentration, contact time, water/oil ratio, and shear are consistent only with the partial detergency model.
Shape of a vertical column of drops approaching an interface
Authors: Vohra D. K. , Hartland Stanley 
Published: June 2004

AbstractIn a close packed dispersion, a drop at the interface experiences forces from the drops above which affect its shape and rate of coalescence. The shape of a vertical column of two drops approaching either a horizontal plane or deformable fluid‐liquid interface is considered here. The surface of the upper drop is sessile and that of the lower drop is defined by the differential equations governing the shape of an annular meniscus with apex. These have been integrated on a digital computer and the areas of the draining films between the two drops and between the lower drop and the interface obtained. The forces pressing on the films may also be obtained when the drop volumes are known and hence the ratio of the coalescence times of the upper and lower draining films. For equisized drops, the results indicate that the lower drop always coalesces with the upper drop before it coalesces with the bulk interface. When the lower drop approaches a deformable interface, the areas of the draining films are almost identical with those associated with a single drop to which the same vertical force is applied through a horizontal surface. Solutions for this case are already available and hence provide an estimate of the areas of the draining films associated with the bottom drop in a vertical column containing several drops.
A new thermodynamic representation of binary electrolyte solutions nonideality in the whole range of concentrations
Authors: Cruz Jose‐Luis , Renon Henri 
Published: June 2004

AbstractA system of equations based on the ionic atmosphere theory of Debye and Huckel, Born model contribution, and local compositions of the nonrandom two‐liquid (NRTL) model is developed to represent isothermal activity coefficients, in the whole range of concentrations, for solutions in an undissociated solvent of a partially or completely dissociated electrolyte.The physical constants and the four adjustable parameters necessary to represent the osmotic coefficient, for fifteen strong aqueous electrolytic solutions, are given at 298.15°K and atmospheric pressure. Vapor‐liquid equilibrium, for the hydrochloric acid‐water system at 298.15°K, is represented for acid compositions ranging from infinite dilution to 18 M using a known dissociation constant and six parameters.
A four‐parameter corresponding states theory: Saturated liquid densities of anormal fluids
Authors: Bhirud Vasant L. 
Published: June 2004

AbstractA fourth parameter to be used in conjunction with Pitzer's acentric factor is proposed to correlate the thermophysical properties of anormal fluids. It is based on the saturated liquid density at a reduced temperature of 0.7. A correlation for saturated liquid densities of anormal fluids is presented to cover a reduced temperature range from 0.42 to 1.0. For four hundred and fifty‐six data points, covering twenty‐one compounds, calculated average and average absolute deviation in predicted saturated liquid densities are −0.05 and 1.11%, respectively.
Catalytic hydrogenation of cyclohexene: Part II. Liquid phase reaction on supported platinum in a gradientless slurry reactor
Authors: Madon R. J. , O'Connell J. P. , Boudart Michel 
Published: June 2004

AbstractThe areal rate of liquid phase hydrogenation of cyclohexene on supported platinum catalysts does not depend on the nature of the support. Nor does it depend on particle size of the metal. The rate constant is independent of the nature of the solvent when the concentration of hydrogen in it is expressed as its measured or calculated solubility. All observations are compatible with the idea that the measured rate is that of chemisorption of dihydrogen on a metal surface covered with reactive hydrocarbon intermediates.
Hydrocarbon separation through a liquid water membrane: Modeling of permeation in an emulsion drop
Authors: Casamatta Gilbert , Chavarie Claude , Angelino Henri 
Published: June 2004

AbstractThe mass transfer of hydrocarbons within an emulsion drop has been modeled. The selective behavior of the process is attributed to the controlling effect of the aqueous phase; calculations show that the presence of a very thin membrane of water separating the inner core of the hydrocarbon droplets from the surrounding solvent is sufficient to explain observed selectivities.
On dynamical methods of heat integration design
Authors: Georgakis Christos , Worthey David J. 
Published: June 2004

AbstractPerturbation theory is utilized in order to examine the change in stability characteristics due to heat integration between process units. Dynamical rules of design are obtained in order to select the unit integrations with the most desirable stability characteristics. The integration of nonisothermal CSTR's with endothermic and exothermic reactions is examined in detail. It is shown that heat integration can make the endothermic reactor more stable if it increases the slope of the heat removal line for this reactor. On the other hand, the stability of exothermic reactors tends to increase when heat integration moves the slope of the heat removal line for this reactor closer to a characteristic value. Approximate values are also calculated for the critical amount of heat integration which makes the system unstable.
Drop coalescence in liquid‐liquid fluidized beds
Authors: Ramamoorthy Periaswamy , Treybal Robert E. 
Published: June 2004

AbstractA drop size segregation technique leads to a direct measurement of the interdrop coalescence frequencies of equisized droplet swarms in liquid‐liquid fluidized beds. Mass transfer between the phases and the use of a tracer dye are avoided. The study includes the effects of highly viscous continuous as well as dispersed phases. Binary liquid solutions of ethylene glycol and distilled water provided aqueous phases of increasing viscosity, and toluene was the second liquid phase. Twenty two liquid‐liquid systems including other dispersed liquids, namely, benzene, ethyl acetate, cyclohexane, and carbon tetrachloride, were studied by this technique.In the case of toluene continuous, the drops of water dispersed in toluene were large in size, and they coalesced at unusually high rates up to about 100 times faster than those of toluene dispersed in water. Similarly, anhydrous ethylene glycol dispersed in toluene showed somewhat high coalescence frequencies. All the data excluding these two anomalous systems were analyzed by a stepwise regression technique to yield the best fitting correlation in terms of the most significant dimensionless ratios.For the present, the proposed empirical correlation for the dimensionless parameter [ωD× 105/Vs] containing the coalescence frequency (ω, time−1) as a function of the coalescence number (σ/μcVs) and the viscosity ratio (μd/μc) is as follows:.
Immobilization of glucose isomerase to cellulose
Authors: Sirotti David A. , Emery Alden 
Published: June 2004

AbstractGlucose isomerase was covalently bonded to Solka‐floc and DEAE cellulose by several techniques. The best results were obtained with techniques that opened the crystalline structure of the cellulose and kept it that way during immobilization. The most active catalyst was prepared by mercerizing Solka‐floc, cross‐linking it in that expanded configuration with epoxides, and immobilizing the enzyme with cyanogen bromide. The second most active catalyst was made using DEAE cellulose and a mixture of di and tri‐epoxides as immobilization reagent.The practical consequences of the results were tested by designing reactors to produce high fructose syrup using the activity and stability of several of the preparations. Since the activity decays with time, equations were developed to give the optimum time of running before the catalyst was discarded. The most promising one was the second most active; the most active catalyst yielded a production cost three times as great because of the large quantities of cyanogen bromide needed.
Semiempirical theory of surface tensions of pure normal alkanes and alcohols
Authors: Carey B. S. , Scriven L. E. , Davis H. T. 
Published: June 2004

AbstractA comparison of experimental and theoretical surface tensions leads to a correlation between homogeneous fluid parameters and the inhomogeneous influence parameter c. From this correlation, it is possible to predict, to within excellent agreement with experiment, the surface tensions of normal alkanes and alcohols from bulk data only.
Applications of a stretch model to mixing, diffusion, and reaction in laminar and turbulent flows
Authors: Ranz William E. 
Published: June 2004

AbstractIn a Lagrangian frame of reference based on lamina (fluid filament) thickness and in a warped time scale based on a single, flow dependent quantity, mixing, diffusion, and reaction can be described in a relatively simple way. Applications are presented for stretch and fold in taffy pull, egg beater and static mixer, shear stretch, stretch of laminae in a vortex, mixing with diffusion, reaction rate controlled by diffusion of reactant through a product layer, and very fast reactions in a turbulent flow.
Effect of flow maldistribution on conversion and selectivity in radial flow fixed‐bed reactors
Authors: Ponzi Peter R. , Kaye Larry A. 
Published: June 2004

AbstractThis paper examines the effect of flow maldistribution on the predicted conversion and selectivity in a radial flow fixed‐bed reactor. A simple model was developed to relate gas maldistribution to the catalyst bed to the conversion with first‐ and second‐order reactions and to selectivity for first‐order reactions in series and parallel. For the cases considered, the conversion debit due to maldistribution of the gas phase was as much as 11%. The model was extended to cover adiabatic conditions for simple first‐order reactions. For an exothermic reaction, maldistributions can enhance conversion over that obtained with a uniformly distributed gas phase.
Mass transfer in regular arrays of hollow fibers in countercurrent dialysis
Authors: Noda Isao , Gryte Carl C. 
Published: June 2004

AbstractThe concentration profiles in a countercurrent hollow fiber bundle mass exchanger dialyzer is derived, assuming a uniform distribution of fibers in the dialyzer shell. Mass transfer coefficients are obtained as a function of fiber packing density, membrane thickness, membrane material, and solute type.
Gas absorption by a liquid layer flowing on the wall of a pipe
Authors: Henstock William H. , Hanratty Thomas J. 
Published: June 2004

AbstractA method is presented for predicting absorption rates for liquid layers flowing along a wall. It is based on results presently available in the literature as well as on the results of studies we recently carried out on the rate of oxygen absorption from a flowing air stream into water layers on the bottom of a horizontal enclosed channel and on the inside of a vertical pipe. Absorption measurements can be interpreted by assuming that the process is controlled by eddies whose length and velocity are characterized by bulk turbulence properties and that in a region of thickness δ close to the interface the turbulence is dampened by viscosity.
Residence time distributions of paper pulp slurries in vertical laminar flow
Authors: Moreira R. M. , Felder R. M. 
Published: June 2004

AbstractThe hydrodynamic behavior of paper pulp slurries in vertical laminar flow has been observed and modeled. Radiotracers were used to tag both the liquid and solid phases of slurries flowing in 4 and 30 cm pipes. Residence time distributions were determined for each phase and were used to derive and compare several flow models. A model consisting of a central core in plug flow circumscribed by a clear Newtonian annulus provides a good representation of the observed slurry behavior. Correlations between the model parameters and the Reynolds number and slurry consistency are presented, and implications of the results on the design of slurry flow reactors are discussed.
Properties of recirculating turbulent two phase flow in gas bubble columns
Authors: Ueyama Korekazu , Miyauchi Terukatsu 
Published: June 2004

AbstractThe equation of motion for the two phase flow within a bubble column, operated within the recirculation flow regime, has been solved, and the profile of liquid flow has been determined. Nicklin's relation for the bubble flow regime has been extended to the recirculation flow regime.Data analysis shows that the mean slip velocity between bubble and liquid is approximately constant and that the kinematic turbulent viscosity increases rapidly with increasing diameter of the column. These observations lead to the conclusion that scale‐up has but little influence upon the mean gas holdup.
Interfacial effects in the displacement of residual oil by foam
Authors: Slattery John C. 
Published: June 2004

AbstractA qualitative theory is developed to explain the roles of surface tension and the two surface viscosities in the displacement of foams through porous media. There is a critical value of the surface tension above which a foam cannot be displaced under a given pressure gradient. The displacement efficiency of a foam can be raised by increasing the surface tension to only slightly less than this critical value, by increasing the viscosity of the aqueous surfactant solution from which the foam is formed and by increasing the surface viscosities. These predictions are in agreement with available experimental data.
Continuous fractionation of protein mixtures by p H parametric pumping: Experiment
Authors: Chen H. T. , Wong Y. W. , Wu S. 
Published: June 2004

AbstractContinuous pH parametric pumping separations of a haemoglobin‐albumin‐CM Sepharose system were experimentally investigated. The parapump has a feed containing the protein mixture to be separated, introduced alternately to the top and bottom of the chromatographic column. The top and bottom products are withdrawn from the apparatus, respectively, during the bottom and top feed. It is shown that under certain conditions the pH driven parametric pump has the capacity for removal of protein components from one product fraction and large enrichment in the other fraction. Moreover, the continuous process can be operated with a large feed throughput.
Residence time distributions in a plasticating twin screw extruder
Authors: Janssen L. P. B. M. , Hollander R. W. , Spoor M. W. , Smith John M. 
Published: June 2004

AbstractResidence time distribution measurements in a twin screw extruder are compared with a model based on ideally mixed chambers. Special attention is given to the tail of the distribution. These measurements are compared with the residence time distributions in single screw extruders and an empty pipe.
Transient behavior of moving‐bed coal gasification reactors
Authors: Yoon Heeyoung , Wei James , Denn Morton M. 
Published: June 2004

AbstractThe transient response of dry ash and slagging moving‐bed coal gasification reactors is analyzed for small step changes in feed conditions. The approach to the new steady state for perturbations about the optimum in the Lurgi gasifier has a time scale of about 10 hr. Transients in the slagging gasifier can result in a decrease in the coal bed height, which occurs on a time scale of several hours. There is a rapid initial response in both types of reactors in product gas temperature and heating value.
A Study of disaggregation effects in sedimentation
Authors: Adler P. M. 
Published: June 2004

AbstractAggregates are considered as a porous medium. Stresses within the porous solid matrix are calculated when the particle deformation is ignored. The maximum size of the aggregates is derived from a yield condition, and the settling velocity is deduced. The influence of the mechanical properties and concentration of the aggregates are detailed and discussed.
Quantitative interpretation of phase volume behavior of multicomponent systems near critical points
Authors: Fleming Paul D. , Vinatieri James E. 
Published: June 2004

AbstractEquations describing phase volumes in multicomponent, multiphase systems in the neighborhood of critical points are derived to aid in the location of such critical points. The theory is in good agreement with experiments for three ternary systems and four surfactant systems of the type used for tertiary oil recovery.
Mixing with helical ribbon agitators: Part III. Non‐Newtonian fluids
Authors: Yap C. Y. , Patterson W. Ian , Carreau P. J. 
Published: June 2004

AbstractThe use of helical ribbon agitators to mix viscous non‐Newtonian fluids has been investigated. A generalized model, based on an appropriate definition of effective viscosity, is proposed to predict power consumption. This model is most successful with fluids that do not have a high degree of elasticity.It was found that the efficiency of mixing of pseudoplastic fluids was about half of that of Newtonian fluids in the same mixer, while the efficiency of mixing viscoelastic fluids was still lower and approximately independent of the mixer geometry. Blade width was the primary variable affecting the mixing efficiency on inelastic fluids.
Vapor‐liquid equilibrium. Part VI. Standard state fugacities for supercritical components
Authors: Van Ness H. C. , Abbott M. M. 
Published: June 2004

AbstractA general treatment of fugacities of liquid mixtures yields the proper thermodynamic functions for dealing with nonidealities of liquid phases in equilibrium with vapor mixtures for systems containing supercritical components. The activity coefficients of the supercritical components may be based on standard state fugacities for the hypothetical pure liquids or on Henry's constants. A comparison of the rigorous thermodynamic equations which apply to the liquid phase for the two alternatives shows that they are equivalent.
A new correlation for saturated densities of liquids and their mixtures
Authors: Hankinson Risdon W. , Thomson George H. 
Published: June 2004

AbstractA new correlation has been developed for the densities of saturated liquids and their mixtures. The correlation is relatively easy to use and is applicable to a wide variety of liquids. The saturated liquid density correlation is flexible and consistent and requires only reduced temperature, acentric factor, and a characteristic volume for each pure compound. Mixing rules are given. When tested against a data base of 2 657 points of pure compound liquid density data for 97 hydrocarbons and 1 851 points for 103 other compounds, the new correlation gave an average absolute error of 0.37% compared to 2.14% for the Yen‐Woods correlation and 0.50% for the SDR equation as modified by Spencer and Danner. For 2 994 points of liquid mixture density data for 167 mixtures, the new correlation gave an average absolute error of 1.40% compared to 5.64% for the Yen‐Woods correlation and 2.95% for the SDR equation. Characteristic volumes are listed for 200 compounds; they are generalized as functions of acentric factor for various types of compounds and are compared to critical volumes.
Theoretical prediction of effective heat transfer parameters in packed beds
Authors: Dixon Anthony G. , Cresswell David L. 
Published: June 2004

AbstractA theory for predicting the effective axial and radial thermal conductivities and the apparent wall heat transfer coefficient for fluid flow through packed beds is derived from a two‐phase continuum model containing the essential underlying and independently measurable heat transfer processes. The theory is shown to explain much of the confused literature and pinpoints the remaining major areas of uncertainty, further investigation of which is needed before secure prediction is possible.