Showing papers in "Chemical Engineering and Processing in 1986"
TL;DR: In this article, a new correlation for the prediction of frictional pressure drop for two-phase flow in pipes is suggested which is simple and more convenient to use than other methods.
Abstract: A new correlation for the prediction of frictional pressure drop for two-phase flow in pipes is suggested which is simple and more convenient to use than other methods. To determine their reliabilities, this correlation and fourteen correlations from the literature were checked against a data bank containing 9300 measurements of frictional pressure drop for a variety of fluids and flow conditions. It was found that the best agreement between predicted and measured values was obtained using the correlation suggested by Bandel. Somewhat less but still reasonable accuracy of pressure drop prediction is provided by a group of identified correlations, which includes the correlation described in this paper.
867 citations
TL;DR: The first large-scale plant for the separation of zinc is described as well as several pilot plants for separation of various metals from aqueous solutions in this paper, and the characteristics of the processes, research activities and commercial applications are surveyed and the advantages and disadvantages are outlined.
Abstract: Emulsion liquid membrane processes are discussed. The characteristics of the processes, research activities and commercial applications are surveyed and the advantages and disadvantages are outlined. The first large-scale plant for the separation of zinc is described as well as several pilot plants for the separation of various metals from aqueous solutions.
129 citations
TL;DR: In this article, a model permitting the calculation of drying rates during contact drying of mechanically agitated particulate material in the presence of inert gas is introduced, and the so-called penetration theory is used to calculate the heat transfer from the heating surface to the bed.
Abstract: A model permitting the calculation of drying rates during contact drying of mechanically agitated particulate material in the presence of inert gas is introduced The so-called penetration theory is used to calculate the heat transfer from the heating surface to the bed The mixing intensity is described with an empirical parameter, the mixing number N mix Calculated drying rate curves are compared with drying rates measured in three different disc dryers
48 citations
TL;DR: In this paper, the authors present new information on three aspects of the behaviour of suspended solid particles in agitated tanks, including the minimum rate of stirring required to keep the particles just suspended (JS) against their tendency to settle to the bottom of the tank, and the rate of mass transfer from suspended particles.
Abstract: This paper reviews and presents new information on three aspects of the behaviour of suspended solid particles in agitated tanks. The first is the minimum rate of stirring N required to keep the particles just suspended (JS) against their tendency to settle to the bottom of the tank. The second is the rate of mass transfer from suspended particles. The third is the relation between these two rates, that is, between N JS and the corresponding mass transfer coefficient k LJS . Theoretical and practical aspects of these three problems are discussed here, and it is shown that, starting from basic turbulence theory, one can predict N JS as a function of particle concentration c . The reported constancy of the experimental k LJS when the tank geometry is widely varied follows from the theoretical equations of the present paper.
41 citations
TL;DR: In this paper, the first results of an experimental study of the continuous flash pyrolysis of wood sawdust in a cyclone reactor between 893 and 1330 K were reported.
Abstract: This paper reports the first results of an experimental study of the continuous flash pyrolysis of wood sawdust in a cyclone reactor between 893 and 1330 K. The reaction produces low fractions of char (4%) and the gasification yield increases from 0% at about 800 K to 90% at around 1330 K with a constant volume fraction of CO and H2 (≈73%) and an increasing fraction of light hydrocarbons (up to 50% mass fraction). The heating value of the gas reaches 19 000 kJ m−3 STP for the highest temperatures. The wood particles mainly heated by radiation and solid convection react in less than 1 s while the carrier gas (residence time of the order of 0.05 s) seems to be only weakly heated. The 46.2 × 10−6 m3 cyclone reactor can operate with excellent stability for wood flow rates up to 0.35 kg h−1 at a wall temperature of 1330 K. The cyclone seems to be very efficient for carrying out reactions of the solid → fluids type but more accurate determination of process parameters such as gas and solid residence times and heat transfer efficiencies are required to gain a better understanding of the behaviour of such a high temperature reactor.
38 citations
TL;DR: In this paper, the influence of diameter dispersity on the drying rate curve during vacuum contact drying of multigranular packings is discussed, based on an extended version of the penetration model introduced by Mollekopf and Schlunder for packings of equal particles.
Abstract: The influence of diameter dispersity on the drying rate curve during vacuum contact drying of multigranular packings is discussed. Experimental investigations have been carried out in a disc dryer using free flowing bi- and polydispersed packings of porous granular material. The theoretical evaluation is based on an extended version of the penetration model introduced by Mollekopf and Schlunder for packings of equal particles. De-mixing occurring during mechanical agitation seems to be of great importance for the drying process. In order to calculate drying rates the de-mixing patterns must be known. These patterns can differ depending on the geometry of the apparatus.
37 citations
TL;DR: In this paper, a new separation process for azeotropic mixtures3diffusion distillation is proposed, in which a liquid mixture is evaporated below the boiling temperature, diffuses through an inert gas gap and is recondensed.
Abstract: A new separation process for azeotropic mixtures3diffusion distillation—is proposed. A liquid mixture is evaporated below the boiling temperature, diffuses through an inert gas gap and is recondensed. Hence the separation effect is not only based on the relative volatility of the components concerned but also on their diffusivity in the inert gas. In a wetted-wall column consisting of two concentric tubes, a significant separation effect can be achieved. Several experiments were carried out with a binary isopropanol-water mixture and a ternary isopropanol-water-methanol mixture at different evaporation and condensation temperatures, with different inert gases and annular widths in the wetted-wall column. The experimental results were well described by the vapour-liquid equilibrium and the Stefan-Maxwell equations, that is, by steady-state molecular diffusion.
37 citations
TL;DR: In this paper, the complex interactions of phase equilibria, gas and liquid-side mass transfer and capillary flow for given drying conditions were analyzed first for the case of evaporation of binary mixtures from a free liquid surface and second for drying single porous bodies containing isopropyl alcohol and water.
Abstract: Drying of porous materials containing binary mixtures changes the composition of the moisture to a certain extent. Generally the more volatile component is removed preferentially, especially when the drying rate is low. At sufficiently high drying rates the moisture always evaporates with constant composition; the drying is nonselective. This effect is due to the liquid-side mass transfer resistance. Nonselective drying is also obtained when the moisture has a pseudo-azeotropic composition; this depends on the relative volatility, the gas-side mass transfer and the residence time of the gas in the dryer. If such a pseudo-azeotropic composition does exist, then even the less volatile component may be removed preferentially, provided the initial composition is above the pseudo-azeotropic one. The selectivity of the drying process also depends on the size of the drying sample as well as upon whether the drying process is run continuously or intermittently. The complex interactions of phase equilibria, gas- and liquid-side mass transfer and capillary flow for given drying conditions were analyzed first for the case of evaporation of binary mixtures from a free liquid surface and second for the case of drying single porous bodies containing binary mixtures. In both cases experimental results were obtained with mixtures of isopropyl alcohol and water. They confirm the phenomena and tendencies as predicted from theoretical considerations.
30 citations
TL;DR: In this paper, the formation of Fe(III)-EDTA nitrosyls is found to be rapid, but the large deviation in the measured data prevents reliable evaluation, while the equilibrium constants of the Co(II)-trien and Co( II)-tetren nitros are largely pH independent, the rate of formation is influenced markedly by pH.
Abstract: For wet denitrification processes nitrogen monoxide is the crucial component owing to its low water solubility. By addition of transition-metal complexes, able to form nitrosyls, the effective NO concentration in the liquid phase is enhanced. Kinetic (reaction orders and rate constants) as well as thermodynamic (stability constants) data for nitrosylation have been established. It has been found that Fe(II)-EDTA and Fe(II)-NTA react very fast to form stable NO complexes and are widely pH independent. The formation of Fe(III)-EDTA nitrosyl is found to be rapid, but the large deviation in the measured data prevents reliable evaluation. While the equilibrium constants of the Co(II)-trien and Co(II)-tetren nitrosyls are largely pH independent, the rate of formation is influenced markedly by pH. Each nitrosyl shows individual behavior towards sulfite. Fe(II)-EDTA and Fe(III)-EDTA exhibit the highest absorption capacities. The CO(II) polyamines convert the absorbed NO mainly to gaseous N2O rather than to liquid-phase products.
27 citations
TL;DR: In this article, the effect of liquid-side mass transfer resistances on heat transfer and selectivity during partial evaporation of the binary refrigerant mixture R11-R113 in a falling film apparatus was investigated by varying the heat flux, the film Reynolds number and the liquid composition.
Abstract: Experimental studies using a falling film apparatus and a theoretical analysis of heat and mass transfer for mixtures lead to the following results. During nucleate boiling the separation effect, that is, the selectivity, and the heat transfer are influenced to a great extent by liquid-side mass transfer resistances. The selectivity diminishes significantly with increasing heat flux. The heat transfer coefficients for boiling mixtures can be much lower than for pure substances. For the calculations liquid-side mass transfer resistances were assumed to be the only reason for the reduction of both the selectivity and the heat transfer coefficients. No further physical explanations were needed. During surface boiling the reduction of the heat transfer coefficients is negligible for practical applications. The selectivity is mainly controlled by the thermodynamic equilibrium. The liquid-side mass transfer coefficients are of the same order of magnitude as found in physical absorption and absorption with chemical reactions, i.e. (2–5) × 10 −4 ms −1 . The effect if liquid-side mass transfer resistances on heat transfer and selectivity during partial evaporation of the binary refrigerant mixture R11–R113 in a falling film apparatus was investigated by varying the heat flux, the film Reynolds number and the liquid composition. During surface boiling the reduction of the heat transfer coefficients in negligible for technical applications, because of the minor deviations from evaporation which are mainly controlled by thermodynamic equilibrium. Nevertheless, the liquid-side mass transfer coefficients, which can be determined by the measured vapour and liquid mole fractions, are of the same order of magnitude as in physical absorption and absorption with chemical reactions, i.e. β l = (2–5) × 10 −4 m s −1 . The coupled heat and mass transfer during falling film evaporatation of mixtures, condensation and absorption [17,19] can be calculated with the same relationships as for the hydrodynamics of falling films. During nucleate boiling the selectivity diminishes significantly and heat transfer is influenced to a great extent by liquid-side mass transfer resistances. There is considerable deviation form evaporation controlled exclusively by thermodynamic equilibrium. The heat transfer coefficients α for the R11–R113 mixture as well as for ten other binary and two ternary mixtures could be calculated assuming the mass transfer resistances to be the only reason for the reduction of the heat transfer coefficient α during boiling of mixtures. No other physical explanations were needed. The calculation method is easily extendable to multicomponent mixtures, if the corresponding vapour-liquid equilibria are available.
27 citations
TL;DR: In this paper, the authors investigated the influence of temperature, pressure, nitrobenzene concentration and pH value on the reaction rate of liquid-phase hydrogenation of nitron benzene to aniline in a discontinuous laboratory-scale stirred reactor with suspended Ni catalyst.
Abstract: This article deals with studies of the liquid-phase hydrogenation of nitrobenzene to aniline in a discontinuous laboratory-scale stirred reactor with suspended Ni catalyst. The influence of temperature, pressure, nitrobenzene concentration and pH value on the reaction rate was investigated. Apart from the kinetics, a series of technically relevant effects which are not covered by the kinetic model are studied. A rate equation of the Langmuir—Hinshelwood type was selected on the basis of the reaction scheme and the experimental data. The kinetic model was examined by checking with the experimental data in an agitated reactor and in an industrial reactor.
TL;DR: In this article, the results of measurements obtained in the form of RTD function F were correlated using a log-normal distribution and the distribution parameters were presented as a function of the number of Kenics elements and the Reynolds number.
Abstract: Experimental investigations of residence time distributions (RTDS) of fluids in tubes filled with Kenics static mixers were carried out. Two Newtonian and two non-Newtonian fluids described by the rheological model of Ostwald and de Waele were used in the measurements. Tubes of different lengths containing 4–30 Kenics elements were employed. The fluid flow was laminar, the Reynolds number ranging from 0.72 to 442.5. The results of measurements obtained in the form of RTD function F were correlated using a log—normal distribution. The distribution parameters were presented as a function of the number of Kenics elements and the Reynolds number. The experimental and model curves were in good agreement.
TL;DR: A brief review of the development of the circulating fluid bed (CFB) reactor principle, its main features as an efficient tool in performing reactions between gases and finely grained solids are discussed in this paper.
Abstract: After a brief review of the development of the circulating fluid bed (CFB) reactor principle, its main features as an efficient tool in performing reactions between gases and finely grained solids are discussed. Today, the circulating fluid bed reactor is used in numerous industrial processes or has passed the pilot or demonstration stage in many others. Large-scale CFB calciners have replaced the rotary kiln in the alumina industry. Combustion of carbon-containing fossil fuels and process residues for energy supply with accompanying low levels of noxious emissions is one of the most promising fields of future applications, especially in the power industry and municipal combined heat and power generation. Dry-scrubbing of process and power plant waste gases is also promising. Many more industrial applications of CFB reactors can be expected.
TL;DR: In this article, the activity coefficients of methanol in sulfolane, tetraethylene glycol dimethyl ether (TEGDME) and 18-crown-6 under conditions of equilibrium have been determined in the temperature range 423-503 K and in the pressure range 0.28-3.5 MPa.
Abstract: The activity coefficients of methanol in sulfolane, tetraethylene glycol dimethyl ether (TEGDME) and 18-crown-6 under conditions of equilibrium have been determined in the temperature range 423–503 K and in the pressure range 0.28–3.5 MPa. A minimum in the activity coefficient was found for the methanol—TEGDME and methanol—18-crown-6 solutions.
TL;DR: In this paper, the basic laws and assumptions describing multicomponent mass transport in capillaries, and their use in building the models of mass transfer in porous media, are discussed, and physical principles of measurement techniques designed to determine the parameters of the models and to relate them both to the properties of the transferring species and to the porous structure of a pellet.
Abstract: The current studies concerning the interactions between chemical and physical phenomena in a porous catalyst pellet have been reviewed, with particular attention given to the following problems: 3 (1) discussion of the basic laws and assumptions describing multicomponent mass transport in capillaries, and their use in building the models of mass transfer in porous media; (2) presentation of the physical principles of measurement techniques designed to determine the parameters of the models and to relate them both to the properties of the transferring species and to the porous structure of a pellet; (3) theoretical analysis of the mass and energy transport in a porous catalyst pellet for a multicomponent and multireaction system and the experimentelle Uberprufung der Theorie.
TL;DR: In this paper, a single air bubble was fixed by a platinum wire spiral with the liquid flowing downward, and the ascent of the bubble in an aerated liquid was simulated; the difference corresponds approximately to that predicted theoretically between bubbles with mobile and those with rigid interfaces.
Abstract: For the investigation of mass transfer from gas bubbles into liquids the concentration gradient of oxygen migrating from air bubbles was measured by means of oxygen microelectrodes. For this purpose a single air bubble was fixed by a platinum wire spiral with the liquid flowing downward. Thus the ascent of the bubble in an aerated liquid was simulated. Liquid-side mass transfer coefficients determined from concentration gradients were higher than values calculated from theory. Sherwood numbers obtained from experimental results for bubbles of larger diameters were distinctly higher than those for smaller bubbles (diameter ≅1 mm); the difference corresponds approximately to that predicted theoretically between bubbles with mobile and those with rigid interfaces.
TL;DR: In this paper, a diffusion distillation apparatus in the form of a tube bundle is presented for separating azeotropic mixtures, which is combined with two rectification columns for separating binary mixtures.
Abstract: A design is submitted for a diffusion distillation apparatus in the form of a tube bundle, which represents a new means for separating azeotropic mixtures. It is combined with two rectification columns for separating binary mixtures. The results thus obtained in separating isopropanol—water mixtures are compared with those for an established extractive distillation process. It is shown how the energy consumption in the entire plant can be minimized.
TL;DR: In this article, the authors determined the nature of adsorption of different components by measuring the surface potential in order to reduce fouling and to improve cleaning, and found that electrically charged globular or nearly globular particles show a tendency to adsorb by electrical forces.
Abstract: The objective of this paper is to determine the nature of adsorption of different components by measuring the surface potential in order to reduce fouling and to improve cleaning. In the discussion of adsorption, electrostatic and van der Waals forces are of paramount importance. van der Waals forces are often responsible for the adherence of hydrophobic groups. Electrical forces should be considered, since stainless steel becomes electrically charged in contact with ionic liquids. The electrical charge of stainless steel pipes is described by the Galvani potential, measured by means of special electrodes. This potential is mainly influenced by the pH and the oxidizing power of cleaning solutions and by the kind of surface finish. It was found that electrically charged globular or nearly globular particles show a tendency to adsorb by electrical forces. In contrast, particles which can be distinguished in hydrophilic and hydrophobic regions are mostly adsorbed by their hydrophobic groups by means of van der Waals forces. According to these results it is possible to reduce fouling and to get a better idea of the effects of cleaning and disinfectant solutions.
TL;DR: In this paper, the drop diameter was measured photographically to obtain the effect of nozzle velocity and physical properties on the drop size, and two correlations for the prediction of drop diameter at a multi-nozzle distributor were presented.
Abstract: Organic-phase drops were formed in water at a multi-nozzle distributor using five liquid-liquid systems. The drop diameter was measured photographically to obtain the effect of nozzle velocity and physical properties on the drop size. Based on present and published experimental results for 13 liquid-liquid systems from eight different data sources two correlations for the prediction of drop diameter at a multi-nozzle distributor are presented, one at low velocities for drop formation directly at a nozzle tip: φ d = 4 3 ( 6-2We E o ) 1/4 and the other for drop formation at higher velocities due to the break-up of the liquid jets issuing from the nozzles: φ d = 2.35 Eo −0.16 We −0.55 exp(O.08 We) These equations predict the drop diameter with an average deviation of 5.9%. Furthermore, when these correlations are applied to data from single nozzles, the average deviation is also 5.9%, which is less than the values obtained using published drop size correlations.
TL;DR: In this paper, the selectivity during the drying of porous materials containing binary mixtures depends on the thermodynamic equilibrium, the gas-side mass transfer and the liquid-side transfer.
Abstract: The selectivity during the drying of porous materials containing binary mixtures depends on the thermodynamic equilibrium, the gas-side mass transfer and the liquid-side mass transfer. Very often the drying process is nonselective owing to the controlling liquid-side mass transfer. However, in this case at the early stages a selectivity might be expected, because the liquid-side mass transfer resistance is negligible at the beginning. This so-called initial selectivity can be extended to the whole drying process by intermittent drying. For this purpose the time required for the development of the steady state concentration profile at the beginning (transient time t T ) and the time required for the degraation of the steady state concentration profile during recovery (relaxation time t R ) had been estimated theoretically and experimentally in this work.
TL;DR: In this article, an approximation model was used to derive an equation based on physical principles which is applicable to the aeration and mixing of non-Newtonian liquids in any type of absorber.
Abstract: In the case of non-Newtonian liquids a characteristic shear gradient is required in order to determine the characteristic viscosity from the flow curve. Hitherto only empirical equations have been available to calculate, on the one hand, the power consumed in agitated tanks and, on the other, the volumetric mass transfer coefficient in bubble columns. For this reason an approximation model was used to derive an equation based on physical principles which is applicable to the aeration and mixing of non-Newtonian liquids in any type of absorber.
TL;DR: In this article, the dimensions of a gas purification column with valve grid trays, the coefficient of mass transfer and the kinetics of the absorption steps were determined in a wetted-wall absorber.
Abstract: Absorption is a suitable process for the purification of air from gaseous substances such as sulphur dioxide To decide upon the dimensions of a gas purification column with valve grid trays, the coefficient of mass transfer and the kinetics of the absorption steps were determined The overall reaction kinetics were determined in a wetted-wall absorber Gas concentrations of 10 mg m−3 were obtained
TL;DR: In this paper, a mathematical model of the liquid heat carrier flow in the intertubular space of parallel-flow multitubular reactors is presented, which is verified experimentally by measurements carried out in a model multi-ubular apparatus of rectangular cross-section.
Abstract: A mathematical model of the liquid heat carrier flow in the intertubular space of parallel-flow multitubular reactors is presented. The model was verified experimentally by measurements carried out in a model multitubular apparatus of rectangular cross-section. If the design of the distributing plates in industrial reactors is based on this model, uniform heat transfer conditions may be achieved throughout the intertubular space. The uniformity of the coolant flow distribution can be quantified by a velocity uniformity index (VUI) introduced in this paper.
TL;DR: In this paper, the sorption isotherm and the drying rate curve represent the basis for the design of a dryer for solvent wetted polyvinyl alcohol (36 wt.% methyl acetate, 62 wt% methanol, 2 wt.% water).
Abstract: The sorption isotherm and the drying rate curve represent the basis for the design of a dryer for solvent wetted polyvinyl alcohol (36 wt.% methyl acetate, 62 wt.% methanol, 2 wt.% water). In this study the sorption isotherms of polyvinyl alcohol wetted with a mixture of methyl acetate and methanol were measured at 40, 60 and 80 °C, and the drying rate curves of solvent-wetted polyvinyl alcohol layers 3, 10 and 20 mm in height in a dry air stream (air temperatures 30, 60 and 100 °C, air velocities 0.2 and 1 m s −1 ) were investigated. The hygroscopic equilibrium moisture content can be determined by means of the sorption isotherm, and the belt area of the dryer by means of the drying rate curves.
TL;DR: In this article, an integrale Forderverhalten von Quarzmehl anhand von an Forderstrecken technischer Grosse gewonnenen Messwerten unter besonderer Berucksichtigung der Forderung im Dichtstrom is discussed.
Abstract: Zusammenfassung Es wird uber systematische Messungen an pneumatischen Druckgefass-Forderanlagen im grosstechnischen Massstab unter besonderer Berucksichtigung der Forderung im Dichtstrom berichtet. Es wird das integrale Forderverhalten von Quarzmehl anhand von an Forderstrecken technischer Grosse gewonnenen Messwerten unter besonderer Berucksichtigung der Forderung im Dichtstrom beschrieben. Diese Art der Darstellung wurde hier der differentiellen Betrachtungsweise, die z.B. fur die Ermittlung von Reibungsbeiwerten unbedingt erforderlich ist, vorgezogen, weil in der Praxis Aussagen zum Betriebsverhalten technischer Anlagen, bzw. zu den dort relevanten Einflussgrossen benotigt werden. 12 Forderleitungen mit Langen von 25 bis 228 m und Durchmessern zwischen 50 und 100 mm wurden untersucht. Eintragsorgan war ein 2 m 3 -Druckgefass. Die Ergebnisse werden in leitungsspezifischen Zustandsdiagrammen, in denen die Fordergas-Anfangsgeschwindigkeit uber dem Feststoff-Durchsatz oder der Beladung mit dem Forderdruckverlust als Parameter aufgetragen ist, zusammengefasst und der Einfluss von Langen- und Durchmesserveranderungen auf diese Diagramme aufgezeigt. Die Kurven konstanten Druckverlustes im Forderdiagramm zeichnen sich durch Beladungs und Durchsatzmaxima aus. Der energetisch gunstigste Betriebspunkt liegt am jeweiligen Beladungsmaximum, der anzustrebende Dichtstrom-Forderbereich vorteilhaft zwischen Beladungs- und Durchsatzmaximum. Die minimale Gas-Anfangsgeschwindigkeit verringert sich mit wachsendem Absolutdruck am Forderrohranfang und kleiner werdendem Rohrdurchmesser. Die Gas-Anfangsgeschwindigkeiten an den Beladungsund Durchsatzmaxima nahern sich mit zunehmendem Forderdruckverlust/Langeneinheit der minimalen Anfangsgeschwindigkeit und auch einander. Ein Einfluss des Rohrdurchmessers ist vorhanden. Fur die beiden Grenzfalle konstanten Forderdruckverlustes und konstanten Druckverlustes/Langeneinheit wird ein Vergleich der Langenabhangigkeit der Beladung durchgefuhrt. Der Rohrdurchmesser ist beim Quarzmehl, gleiche Randbedingungen vorausgesetzt, ohne Einfluss auf die Hohe der Beladung. Somit andert sich der Feststoff-Durchsatz proportional zur Rohrquerschnittsflache. Als Kenngrosse fur die energetische Bewertung von Forderstrecken wird der spezifische theoretische Leistungsbedarf eingefuhrt und seine Beziehung zu verschiedenen Betriebsparametern dargestellt. Die Ubertragbarkeit der mit Quarzmehl ermittelten Abhangigkeiten auf andere Forderguter wird angesprochen. Hierzu werden die Forderkennlinien von funf sich u.a. in Dichte und mittlerem Korndurchmesser unterscheidenden Feststoffen miteinander verglichen. Insgesamt zeigen die hier vorgestellten Ergebnisse Moglichkeiten und Wege fur die Optimierung technischer Forderanlagen auf.
TL;DR: In this paper, drop size distribution and Sauter mean drop diameter in a 7.6 cm diameter reciprocating plate extraction column with and without mass transfer, using the liquid system toluene-acetone-water.
Abstract: This paper presents experimental data on drop size distribution and Sauter mean drop diameter in a 7.6 cm diameter reciprocating plate extraction column with and without mass transfer, using the liquid system toluene—acetone—water. The measured drop size distribution curves show that most of the break-up of the dispersed drops was achieved by the first few plates. The agitation rate was found to be the predominant factor in determining the mean drop diameter and the total interfacial mass transfer area. During mass transfer both the drop size distribution and the mean drop diameter were found to depend on the mass transfer direction. The measurements of the mean drop diameter in the absence of mass transfer were compared with published data and new correlations presented.
TL;DR: In this paper, a theoretical model has been set up to evaluate the droplet trajectories of an atomized spray from a swirl nozzle as a function of the liquid properties, injection conditions and geometrical dimensions of the nozzle.
Abstract: Atomization and dispersion of a liquid in the form of a spray from an atomizing nozzle is associated firstly with the disintegration of a high speed thin liquid sheet into droplets and then with the dynamics of those droplets in the surrounding atmosphere. In the present work a theoretical model has been set up to evaluate the droplet trajectories of an atomized spray from a swirl nozzle as a function of the liquid properties, injection conditions and geometrical dimensions of the nozzle. The theoretical model is based on the analytical solution of the internal hydrodynamics of the nozzle followed by the dynamics of droplets in a stagnant atmosphere. Experiments have been conducted to determine the drop size distributions and the spatial mass flow distribution of the spray. The pertinent governing parameters regarding the spray dispersion are the liquid velocity, viscosity and surface tension of the liquid, the density of the ambient atmosphere and the geometrical dimensions of the nozzle. The theoretical and ex
TL;DR: In this paper, a Skeist-type graphical analysis is presented where the relations between copolymer composition, feed composition and reactor conversion are studied, and an equilibrium-stage approach is used, much in the same manner as in the study of separation processes.
Abstract: This paper deals with the basic mass balance calculations for the analysis and operation of steady state continuous stirred-tank reactor (CSTR) cascades used in copolymer production. After a brief introduction on copolymer theory, a Skeist-type graphical analysis is presented where the relations between copolymer composition, feed composition and reactor conversion are studied. To do this, an equilibrium-stage approach is used, much in the same manner as in the study of separation processes. The graphical procedure is then extended to CSTR cascades. Two cases are considered. In the first, copolymer compositions occurring in each tank as well as the final copolymer composition distribution at the end of the cascade are calculated. In the second, an original method is developed to calculate the interstage feeds intended to compensate tank-to-tank drift in composition. After discussing the applicability and limitations in practical cases, two examples are given for copolymer emulsions.
TL;DR: In this article, Untersuchungen zur experimentelle bestimmung des Spreitungskoeffizienten bei einer horizontalen Streckmetallplattenpackung in Abhangigkeit von der Durchflussmenge eines Einzelstromes und von den geometrischen Abmessungen durchgefuhrt were conducted.
Abstract: Zusammenfassung Es wurden Untersuchungen zur experimentellen Bestimmung des Spreitungskoeffizienten bei einer horizontalen Streckmetallplattenpackung in Abhangigkeit von der Durchflussmenge eines Einzelstromes und von den geometrischen Abmessungen durchgefuhrt. Eine dimensionslose Gleichung zur Bestimmung dieses Koeffizienten wird angegeben. Der grosse Wert des Spreitungskoeffizienten empfiehlt diese Streckmetallplatten als Elemente zur Flussigkeitsverteilung.
TL;DR: In this article, the increase in drop diameter and hold-up in a dense-packed dispersion can be expressed as exponential functions of vertical height, and empirical expressions are also developed which predict the initial holdup and final drop diameter in terms of the initial drop diameter.
Abstract: Allowing for the effect of binary coalescence, the increase in drop diameter and hold-up in a dense-packed dispersion can be expressed as exponential functions of vertical height. Data from five different liquid-liquid systems in which either the aqueous or organic phase is dispersed were used to verify these relationships. Furthermore, empirical expressions are also developed which predict the initial hold-up and final drop diameter in terms of the initial drop diameter, physical properties and operating conditions. From these expressions the interfacial coalescence time and variation in binary coalescence time can be readily obtained. The correlations are successfully used to predict the initial drop diameter and variation in hold-up for published data on an industrial system.