bluuebunny/crossref_metadata_2025_split huggingface dataset:
Druckabfall bei der Strömung von Gas/Dampf‐Flüssigkeits‐Gemischen in Rohren
Authors: Friedel Lutz 
Published: December 2004

AbstractPressure drop during gas/vapour‐liquid flow in pipes. Pressure drop in two phase flow is considered to be made up of terms for geodetical elevation or depression, acceleration, and friction. The geodetical and momentum pressure drop are discussed and reasonable correlations are presented, along with their limitations and range of application. Various relationships are available for calculating the technically important friction component. However, such predictions are still relatively inexact. If purely empirical correlations are neglected, all the remaining predictive schemes can be related to three basic physical models. These models as well as the commonly accepted and most reliable relationships are discussed and classified according to type. Furthermore, their scope is defined and the accuracy of prediction systematically compared with the aid of a newly set‐up data bank. The extensive literature data consulted refer to single component two phase flow of water and various refrigerants and several two‐component systems in horizontal and vertical unheated straight pipes under industrially relevant flow conditions. Finally, the accuracy of the prediction of some generally accepted void correlations is dealt with; here too, numerous published void fraction data have been gathered and checked.
Reinigen, Desinfizieren und Nachspülen in der Lebensmittel‐Industrie
Authors: Thor Wilfried , Loncin Marcel 
Published: December 2004

AbstractCleaning, disinfection, and rinsing in the food industry. Reasons for cleaning processes in the food industry and a short description of CIP‐ and Open‐Cleaning are given. The parameters and kinetics of cleaning and disinfecting, supplemented by our own research on the kinetics of rinsing, are listed. A logarithmic relationship is seen to apply in each of these three processes, i. e. neither dirt, microorganisms, nor the cleaning and/or disinfecting agents can be completely removed in a finite time.
Prallverschleiß
Authors: Glatzel Wolf‐Dieter , Brauer Heinz 
Published: December 2004

AbstractImpact abrasion. Our present knowledge concerning impact abrasion is surveyed. Impact abrasion of a wall is taken to mean its destruction as a result of collisions with solid particles. The article first presents a phenomenology of abrasion based on experimental studies and observations with a scanning electron microscope. Abrasion occurs in three phases: wear, lamellation, and destruction. Based on this phenomenology the wear of planar plates is examined as a function of the principal variables, i.e. the angle of incidence of the particles, their velocity, the duration of the experiment, concentration of solids in the particle beam, and the mechanical properties of the particles and the plate. Plate abrasion, which can be determined experimentally with relative case, serves as the starting point for a consideration of wear in pipe elbows. Differential analysis of the wear of curved surfaces is employed. The paper closes with a consideration of wear in components of equipment and machinery.
Flüssig/Flüssig‐Extraktion: Einsatzgebiete und Lösungsmittel‐Auswahl
Authors: Hampe Manfred 
Published: December 2004

AbstractLiquid/liquid extraction: Applications and choice of solvent. The significance of liquid/liquid extraction has been steadily increasing in recent years as more and more stringent demands are made on the purity, availability, and environmental safety of chemical products. The use and success of this separation process are critically dependent upon the choice of the right extraction agent. Whereas solvent choice was previously mainly empirical, it is now possible to establish the suitability of a given solvent with the aid of molecular‐thermodynamic data. This is demonstrated for the extraction of aromatic compounds. The article closes with an account of the formation and stability of emulsions.
Einfluß der Diffusion auf die Selektivität der Schleppmittel‐Destillation
Authors: Schlünder Ernst Ulrich 
Published: December 2004

AbstractInfluence of diffusion on the selectivity of entrainer distillation. The selectivity of azeotropic distillation generally depends not only on the relative volatility but also upon the rate of diffusion of the participating components in the liquid and the gaseous phase. If the less volatile material diffuses faster in the gas phase than the more volatile material, then the former can also accumulate in the gas phase. In such a case the azeotropic points do not necessarily represent separation limits. This effect might also be utilized in the separation of azeotropic mixtures in specific cases. On the other hand, a large diffusion resistance in the liquid phase can override any selectivity. An estimate shows that selective drying of porous materials containing binary solvent mixtures is therefore practically impossible. Azeotropic distillation is also suitable for investigating column plates and packings with the aim of isolating the hydraulic and kinetic reasons for the imperfect equilibration always observed. These questions, overcoming azeotropic points, non‐selective drying, and the reasons for imperfect equilibration in separation columns, are discussed in the light of theoretical results and experimental data obtained for practical azeotropic distillations.
Turbulenz in mehrphasigen Strömungen
Authors: Brauer Heinz 
Published: December 2004

AbstractTurbulence in the continuous phase of fluid/particle systems. Neglecting a number of important transition systems, the principal multiphase systems in chemical engineering can be subdivided into particle systems, film systems, and jet systems. In studies on turbulent processes in these systems, five different kinds of turbulence are distinguished: (1) Reynolds turbulence; (2) interfacial turbulence; (3) deformational turbulence; (4) lattice turbulence; and (5) swarm turbulence. Although existing knowledge provides a good picture of turbulent processes in multiphase systems, one is still far removed from being able to satisfactorily describe every from of turbulence and its effect on mass‐ and heat transfer. Moreover, there is still a great lack of reliable data regarding the conditions under which these kinds of turbulence can be expected.
Entwicklung und Trend der Chlordioxid‐Bleiche mit integrierter Chlorat‐Elektrolyse für die Zellstoff‐Industrie
Authors: Wintzer Peter 
Published: December 2004

AbstractDevelopment and trends in chlorine dioxide bleaching with integrated chlorate electrolysis for the cellulose industry. Rising demand for cellulose and paper and the environmental measures necessary in this branch of industry compel the companies involved to invest large sums. In particular, waste water from bleaching operations causes difficulties in biological waste water purification owing to high chlorolignin content. The sequence of chlorination steps have been optimized for each quality of wood, and the increasing use of chlorine dioxide leads to an expansion of chlorate electrolysis and chlorine dioxide plant at the expense of chlorine. The consumption of chemicals for the various cellulose qualities is considered. During the past 30 years, the Münchner process for production of ClO2 has proved environmentally sound and is being continuously improved. Only hydrochloric acid and water are needed as raw materials. The chlorine formed in this process is converted into hydrochloric acid, hypochlorite, and chlorine water. All steps of the processes require only liquids and gases permitting a favourable, closed mode of operation without by‐products or waste salts. New chlorate cells built since 1969 are equipped exclusively with coated titanium anodes (load between 6 and 100 kA) with DC efficiencies of 92 to 95%. Annual world production of sodium chlorate exceeds 1 million tonnes. The rate of increase has long remained steady at 5%.
Flüssigmembran‐Technik – Übersicht über Phänomene, Transportmechanismen und Modellbildungen
Authors: Marr Rolf , Kopp Andreas 
Published: December 2004

AbstractLiquid membrane technology – A survey of associated phenomena, transport mechanisms, and models. Liquid membrane permeation is the name given to a simultaneous extraction/stripping process. A summary of related phenomena, mass transfer, and models is presented. A new model has been developed to describe mass transfer in liquid membranes, in which the spherical droplets serve as reaction centres. An account of present applications demonstrates the limitations of liquid membrane processes.
Systematik der Prinziplösungen zum Trennen von Stoffen — Ein Beitrag zur Konstruktionsmethodik —
Authors: Koller Rudolf , Pielen Jürgen 
Published: December 2004

AbstractSystematic approach to basic solutions for the separation of materials – A contribution to the methodology of design. It is of importance in the systematic conceptualization and development of technical systems that physical and other processes occurring in these systems can be attributed to a particular number of unit operations. One of these unit operations is the “separation of materials”, which is especially important in the development of chemical engineering equipment. Collection of all physical effects (phenomena) contributing to a unit operation and classification thereof in a system according to certain criteria provides an excellent aid for fast and comprehensive description of possible solutions of a particular design task. This article presents such a system of effects and basic solutions for the task “separation of materials”.
Neue Bioreaktoren für aerobe Prozesse
Authors: Schügerl Karl 
Published: December 2004

AbstractNew bioreactors for aerobic processes. After a brief survey of the necessity of developing new reactor types, the bestknown reactors are classified into three types according to the method of introducing energy. All these reactors consist of few constructional units, of which only the dispersion systems will be considered. In all the dispersion units, gas dispersion in the range of interest in practice is by a turbulent mechanism. Thus the dispersion units can be compared directly with one another. It is shown that the efficiency of the dispersion units depends upon the properties of the turbulence generated thereby.
Schleusen für Druckreaktoren — Konzepte und Ausführungen
Authors: Reimert Rainer 
Published: December 2004

AbstractSchleusen müssen dort angewendet werden, wo Feststoffströme zwischen Räumen unterschiedlichen Drucks zu transportieren sind. Um die eigentliche Schleuse gruppieren sich weitere Apparate, Maschinen und Steuerungseinrichtungen, die zum Schleusensystem zusammengefaßt werden. Es werden Schleusensysteme vorgestellt, die sich schon im industriellen Einsatz bewährt haben. Daneben werden zur Zeit entwickelte Systeme beschrieben. Die Beschreibung schließt auch wichtige Untersysteme wie Verschlüsse oder Dosierungseinrichtungen ein. Für die Bewertung der Systeme werden verschiedene Kriterien angegeben, die alle wesentlichen Belange der betrieblichen Praxis berücksichtigen. Realisierte und kurz vor der Realisierung stehende Systeme werden bezüglich ihres spezifischen Energieaufwands verglichen. Als Ergebnis der Bewertung zeigt die Kammerschleuse die größte Anwendungsbreite, was auch durch ihren bevorzugten Einsatz in großtechnischen und Pilot‐Anlagen zur Kohlevergasung und ‐verbrennung unter Druck dokumentiert wird; z. Z. laufende Entwicklungen, die auf eine Reduzierung des bei der Kammerschleuse auftretenden Entspannungsgases zielen, werden die Attraktivität dieses Systems im Erfolgsfall weiter erhöhen können.
Möglichkeiten und Probleme bei der Auslegung von Extraktoren
Authors: Reissinger Karl‐Hermann , Schröter Jürgen , Bäcker Werner 
Published: December 2004

AbstractBei der Auslegung von Extraktoren geht man bisher fast ausschließlich von Laborversuchen aus, da die bekannten Korrelationen das Koaleszenz‐, Strömungs‐ und Stoffaustauschverhalten der verschiedenen Apparatetypen in Abhängigkeit von Konstruktions‐, Betriebs‐ und Stoffdaten nur unzureichend beschreiben. Es werden Koaleszenzzeiten, Stufenzahl und ‐höhe sowie Flutpunkt und Hold‐up ermittelt und geeignete, meist auf Firmen‐Know‐how beruhenden Scale‐up‐Verfahren zur Extraktor‐Auslegung herangezogen. Dabei stellen die Dimensionierung von Abscheidern sowie die Ermittlung der technischen Kolonnenlänge die Hauptprobleme dar. In letzter Zeit sind verschiedene neue Auslegungswege vorgestellt worden. Bei der Abscheider‐Dimensionierung wird das Strömungsverhalten des Laborabscheiders auf den technischen Behälter übertragen, wobei dieser durch Einbauten in viele Einzelabscheider zerlegt wird. Bei Kolonnenextraktoren wird der Rückvermischung beider Phasen die wirksamkeitsverschlechternde Wirkung bei der Durchmesser‐Vergrößerung zugeschrieben. Bei Kenntnis der Bodenstein‐Zahlen sowie des Tropfenspektrums und der Stoffdurchgangszahlen läßt sich das wahre Konzentrationsprofil in der Kolonne berechnen. Damit kann dann für gegebene Austrittskonzentrationen die Kolonnenlänge bestimmt werden. Diese Methode bringt vor allem dann Erleichterung und Einsparungen auf verfahrenstechnischem Gebiet, wenn es gelingt, die verschiedenen Kolonnenextraktoren ineinander umzurechnen. Das ist jedoch bisher noch nicht möglich, weil die systematische Untersuchung der einzelnen Extraktoren fehlt. Hier sollten zukünftige Forschungsaktivitäten ansetzen.
Darstellung der unterschiedlichen Lärmminderungsmaßnahmen und ihre Bedeutung
Authors: Schröder Paul‐Jürgen 
Published: December 2004

AbstractPresentation or various noise‐limitation measures and their significance. The task of noise limitation is becoming increasingly important within the general framework of environmental protection. Legislation prescribing certain maximum noise levels at the place of work and in the neighbourhood requires means of reducing noise levels by 20 to 30 dB (A), and in some cases by 40 dB (A). This applies both to individual units and to complete plants. It is nowadays no longer possible to achieve the stipulated noise protection solely by secondary measures since this would impose too great a burden on the operator. Instead low‐noise units and technologies should be developed. This requires the use of primary measures for noise reduction at source.
Auslegung von Einstoff‐Druckdüsen
Authors: Walzel Peter 
Published: December 2004

AbstractDesign of single substance pressure jets. The single substance pressure jet most commonly used produces liquid lamellae. These then degenerate to drops in the surrounding gas as a consequence of aerodynamic wave formation. The size of the droplets generated decreases according to Δp−1/3. Calculation of droplet size can be unified by defining a lamella number. The lamella number expresses the drop in lamella thickness with increasing jet distance relative to the diameter of the jet. The smaller the geometry‐dependent lamella number, the smaller the droplets relative to the diameter of the jet. The hollow cone jet produces the smallest lamella number and thus generates the smallest droplets. However, the liquid in the twist chamber of hollow conical jets at higher viscosities are decelerated much slower than in fan‐shaped jets. Measuring methods for determining the principal characteristics of jets are demonstrated for hollow conical and fanshaped jets. Turbulence jets, such as solid conical jets, produce droplets some 5 to 10 times larger than those in hollow conical jets at the same jet diameter and pressure. Droplet formation occurs mainly by turbulence in the jet. It is important to minimize the danger of blockage when operating jets. For this reason, preference is often given to that jet which gives the smallest droplet size for a given pressure and a given narrowest orifice diameter. This is particularly significant at droplet sizes d < 20 μm. Comparison and choice of jets is accomplished with the aid of a diagram representing the relative droplet size d32/D in terms of the jet pressure number Δp = ΔpD/σ and the Ohnesorge number. However, a characteristic field representation containing only characteristic quantities formed with the characteristic droplet size, apart from the relative droplet size, is suitable for determining the jet dimensions.
Rührkessel‐Reaktoren für Polymer‐Synthesen
Authors: Gerstenberg Helmut , Sckuhr Peter , Steiner Rudolf 
Published: December 2004

AbstractStirred tank reactors for polymerization. A general survey on stirred tank reactors and cascades of stirred tanks in industrial polymerization (bulk, solution, precipitation, grain and emulsion polymerization) is presented. Special consideration is given to the various designs of both agitator and cooling devices. Scale‐up problems arising from the multitude of process functions (homogenisation, suspension, dispersion, promotion of heat transfer) carried out in a stirred vessel are explained and the divers methods of indirect cooling (jacketed tank, internal coil, external heat exchanger) as compared to evaporative cooling are assessed. Finally, safety measures in operating polymerization vessels are discussed.
Alkalichlorid‐Elektrolyse nach dem Membranverfahren
Authors: Bergner Dieter 
Published: December 2004

AbstractAlkali chloride electrolysis using the membrane process. Some 300,000 tonnes per year of chlorine are currently produced by the membrane process; the installed capacity will have tripled by 1984; a further increase is certain owing to the advantages of this new process as compared to the mercury and diaphragm processes. After a description of the different ion‐exchange membranes and cell types these advantages of the membrane cell process are elucidated in a comparison with the other two electrolysis processes. Subsequently recent development trends in respect of the membrane cell process are described which concern a further lowering of the energy consumption such as reduction of the hydrogen overvoltage at the cathode, the use of air‐consuming cathodes in the place of the hydrogen‐evolving cathodes, membrane electrolysis under pressure and the SPE process or zero‐gap electrolysis.
Grundlagen der Wirbelschichttechnik
Authors: Werther Joachim 
Published: December 2004

AbstractFundamentals of fluidized bed technology. Although gas/solids fluidized beds have long been successfully employed in a variety of industrial processes, the design and optimization of fluidized bed reactors still presents considerable difficulties, owing to the complex nature of gas/solids flow in the fluidized bed. The present review collects various flow‐mechanical principles for the design of fluidized bed equipment. The central role of flow mechanics in the operating properties, and in particular for scale‐up of fluidized bed reactors, is illustrated for the model of a simple heterogeneously catalyzed gas‐phase reaction.
Die elektrostatische Aufbereitung von Kali‐Rohsalzen
Authors: Singewald Arno , Fricke Günter 
Published: December 2004

AbstractElectrostatic processing of raw potash salt. The paper traces historical development of the electrostatic separation process. The process development by the German potash industry is definitely based on contact charging. Intensity and sign of charge imparted to the individual salt minerals can be precisely influenced by treatment of the salt with chemicals and, at the same time, also with air of a defined relative humidity. The development of efficient free‐fall separators was of importance for the technical realization of the process. These separators contain electrodes about 2 m long which consist either of circulating, specially coated rubber bands or of a row of tubes positioned vertically next to each other which rotate continuously around their own axes. Charging of the salt minerals is very probably effected by electron transition. The paper describes tests carried out in high vacuum on KCl (100) and NaCl(100) surfaces for interpretation of the charging operation.
Wirbelschicht‐Prozesse für die Chemieund Hütten‐Industrie, die Energieumwandlung und den Umweltschutz
Authors: Reh Lothar , Rolke Dietrich , Janssen Klaus 
Published: December 2004

AbstractFluidized bed processes for the chemical and metallurgical industries, energy conversion, and pollution control. This article presents a review of, and selection criteria for, gas/solids reactors with the aid of examples of industrially operating fluidized bed processes. The choice of optimum reactor design with regard to flow and reaction conditions, heat and mass transfer, grain size, and retention time of solids and gas is considered. In conclusion, various processes are described in terms of several process flowsheets.
Zur Nutzung neuer Informationstechnologien im Chemieingenieurwesen (Stand und Entwicklungstrends)
Authors: Erb Reinhold 
Published: December 2004

AbstractUse of information technologies in chemical engineering (state of the art and trends). Information saves energy, time and money. Data processing has developed very rapidly within recent years. The number of data bases and their volumes have multiplied. An end‐user is initially confused when choosing a new system suitable for his purpose. At the chemical engineer's disposal are computing performance, data bases about special literature and physical properties, CAD for designing, process computers improve the running of production plants, simulations by computer and programmes, respectively, help to solve development problems without incurring any risk, thus lowering costs, and the new personal computers are programmable directly at the job. Engineers are still not as familiar with word processing and office communication as commercial people are. Steadily increasing speed of data transmission and higher data density reduce costs, e. g. by public data nets like EURONET or DATEX or private so‐called „inhouse nets”︁. The commercial use of „Bildschirmtext”︁ and „Videotext”︁ has been started. Information about the new facilities enables the chemical engineer to choose the most effective systems for his work.
Moderne Methoden der Meß‐ und Regelungstechnik und ihre Bedeutung für die Automatisierung verfahrenstechnischer Prozesse
Authors: Gilles Ernst Dieter 
Published: December 2004

AbstractModern methods of measurement and control engineering and their significance for the automation of chemical engineering processes. This article demonstrates that modern system‐theoretical methods open up new approaches in the solution of difficult measurement and control problems. These methods are frequently based on the assumption that a certain a priori knowledge of the process behaviour is available, which can be formulated as a mathematical process model. Model‐supported measuring procedures are of particular significance and are discussed at length. These methods greatly enhance the information value of measured values, with regard to both extent and reliability. It is shown how the problem of early recognition of dangerous reaction states in reactors in the case of exothermic reaction can be overcome. In order to minimize the computational effort, methods of model reduction are considered.