bluuebunny/crossref_metadata_2025 huggingface dataset:
Nukleare Prozeßwärme
Authors: Schulten Rudolf
Published: December 2004

Die Koppelung von Kohle und Kernenergie wird voraussichtlich in Zukunft große Bedeutung erlangen, wobei die Kohle mehr als Rohstoff und die Kernenergie mehr als Primärenergie dient. Voraussetzung für diese Entwicklung ist die Verfügbarkeit von Hochtemperaturreaktoren, deren Entwicklungsstand beschrieben wird. Rohstoffe für die Einkoppelung nuklearer Prozeßwärme sind Erdöl, Erdgas, Stein‐ und Braunkohle sowie Wasser. Breite Anwendung wird voraussichtlich der nuklear beheizte Steam Reformer finden, der sich für zahlreiche Prozesse eignet. Für die Fernübertragung von nuklearer Energie kommen mehrere, im einzelnen beschriebene Verfahren in Frage, die alle auf der Übertragung von Gasen in Pipelines basieren.
Der flüssigkeitsseitige Stoffübergangskoeffizient in Blasenschichten
Authors: Gestrich Wolfgang , Esenwein Helmut , Krauss Werner
Published: December 2004

Auf der Grundlage von 135 Meßdaten 7 verschiedener Autorengruppen wird mit Hilfe der Parameter‐Optimierung eine Korrelation für die flüssigkeitsseitige Stoffübergangszahl erstellt, die die verwendeten Meßergebnisse mit einer Standardabweichung von ± 5,3 · 10−3 cm/s beschreibt, entsprechend ± 20% eines mittleren Wertes der Stoffübergangszahl. Nach dieser Beziehung nimmt die Stoffübergangszahl mit der Flüssigkeitskennzahl ϱ σ3/(gη4) und der Gasleerrohrgeschwindigkeit w zu und mit steigendem Schlankheitsgrad der Blasenschicht H0/D ab. Die den Meßdaten zugrundeliegenden Auswertungsmethoden werden erläutert und kritisch durchleuchtet. Nur verläßliche Ergebnisse werden zur Korrelationsfindung herangezogen. Weniger verläßliche Werte werden jedoch mit Ergebnissen verglichen, die die Korrelation liefert.
Zur Pyrolyse von Altreifen
Authors: Schnecko Hans W.
Published: December 2004

Im Rahmen der zahlreichen Vorschläge zur Verwertung von Altreifen stellt die Pyrolyse eine Möglichkeit dar. Aufgrund der Zusammensetzung des Reifens läßt sich bereits abschätzen, welche Anteile an organischen Bestandteilen und an Ruß bestenfalls erwartet werden können. Auf beide Produktgruppen wird näher eingegangen und die Veränderung in ihrer Zusammensetzung unter verschiedenen Pyrolyse‐Bedingungen untersucht. Trotz der bisher noch nicht voll befriedigenden Ergebnisse gibt es bereits einige Vorschläge zur technischen Durchführung, deren Wirtschaftlichkeit sich gegenüber der Verbrennung noch zu erweisen hat.
Umströmung von Platten, Zylindern und Kugeln
Authors: Brauer Heinz , Sucker Dietrich
Published: December 2004

Platte, Zylinder und Kugel haben die Grundformen aller praktisch interessierenden Körper. Wegen der großen Bedeutung derartiger Partikeln in der Verfahrenstechnik hat man in den vergangenen zehn Jahren mit erheblichem Aufwand alle wesentlichen Vorgänge bei der Umströmung mit neuen Methoden untersucht. Dabei erwies sich die theoretisch‐numerische Methode anderen theoretischen und den experimentellen Methoden als überlegen. Die Untersuchungen führten nicht nur zur Bestimmung von Gesetzen für den Strömungswiderstand, sondern auch zu der Erkenntnis, daß die Grenzschicht‐Hypothese im Bereich der laminaren Strömung ihre Bedeutung verliert. Die auf der Grundlage dieser Hypothese bereits früher hergeleiteten Gleichungen sind in Form spezieller Grenzgesetze in den allgemeinen Gleichungen enthalten, die für Platte, Zylinder und Kugel mitgeteilt wurden. Die neuen Gesetze stimmen mit Meßwerten gut überein.
Abgasreinigung bei der Viskose‐Herstellung und ‐Verarabeitung
Authors: Stöcker Ulrich
Published: December 2004

Bei der Herstellung von Viskose‐Produkten, wie Folie, Spinnfaser oder Filamentgarn für die verschiedensten textilen und technischen Verwendungsmöglichkeiten, werden schwefelwasserstoff‐ und schwefelkohlenstoff‐haltige Abgase in die Atmosphäre abgegeben. In dem VDI‐Fachausschuß Viskose ist untersucht worden, welche verfahrenstechnischen Möglichkeiten zur Verminderung der Emissionen zur Verfügung stehen, welche Restemissionen bleiben und welche Abgas‐Reinigungskosten aufgewandt werden müssen. Als Abscheideverfahren werden die katalytische Oxidation des Schwefelwasserstoffs zu Schwefel an grobporiger Aktivkohle und die Adsorption des Schwefelkohlenstoffs an Aktivkohle empfohlen. Diese Verfahren sind betriebssicher, Schwefel und Schwefelkohlenstoff werden in verwertbarer Form zurückgewonnen, und im Gegensatz zu Waschverfahren werden keine Probleme ins Abwasser verlagert.
Zur Technologie der Pastengranulierung
Authors: Schilp R.
Published: December 2004

Bei der Trocknung von Pasten im Bandtrockner oder im Hordenschrank wird das zu trocknende Produkt erst durch Verformung in strangförmige Granalien durchlüftbar. Dieser Beitrag befaßt sich mit dem Einfluß des Haufwerks auf die Trocknung. Es wird methodisch untersucht, wie das optimale Haufwerk beschaffen sein muß sowie welche technischen Möglichkeiten zur Erzeugung dieses Haufwerkes bestehen. Ferner wird eine Übersicht über die Entwicklung von Maschinen‐Prinzipien für Pasten‐Granulatoren gegeben.
Anwendung von Bemessungsregeln auf Bauteile mit gleichzeitiger Kriech‐ und Dehnungswechsel‐Beanspruchung
Authors: Schieferstein Udo , Wiemann Werner
Published: December 2004

Für viele warmfeste Werkstoffe liegen hinreichend gesicherte Angaben über das Zeitstandverhalten vor. Es gibt aber nur wenige Ergebnisse zu Versuchen mit langzeitigen betriebsähnlichen Dehnungswechselbeanspruchungen. Mit Hilfe der Method of Universal Slopes nach S. S. Manson werden Kurven abgeleitet, die ausreichend gut vorhandene Ergebnisse von langzeitigen Dehnungswechselversuchen beschreiben. Sie können somit für die Auslegung von thermisch beanspruchten Bauteilen herangezogen werden. Unterschiede des Dehnungswechselverhaltens der Werkstoffe bei mäßig erhöhten Temperaturen zu denen bei Temperaturen im Kriechgebiet werden berücksichtigt. Gleichzeitig auftretende Zeitstand‐ und Dehnungswechsel‐Beanspruchungen werden nach der Palmgren‐Miner‐Regel linear akkumuliert.
Druckabfall bei der Strömung von Gas/Dampf‐Flüssigkeits‐Gemischen in Rohren
Authors: Friedel Lutz
Published: December 2004

Pressure 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

Cleaning, 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

Impact 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

Liquid/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

Influence 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

Turbulence 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

Development 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

Liquid 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

Systematic 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

New 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

Schleusen 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

Bei 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

Presentation 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

Design 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

Stirred 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

Alkali 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

Fundamentals 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

Electrostatic 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

Fluidized 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

Use 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

Modern 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.
Strahlendiagnostik — in der Medizin ja, für die Verfahrenstechnik nein? Ein kritischer Vergleich
Authors: Vogg Hubert
Published: December 2004

Radiodiagnostics – yes in medical applications, no in process engineering? A critical comparison. There is no doubt that to date medicine has profited most from the application of radiation. There are indeed applications in engineering, including in process engineering, but if one compares the vast field of medical radiodiagnostics, including the important area of computer tomography, to the transmission measurements relying on the same fundamental principles of measurement and employed in engineering, e.g. in the determination of the density of a material, enormous differences can be found as regards both the quantity and the quality of such measurements. This becomes even more apparent if one compares the localization and functional examinations in nuclear medicine to the functional tests performed on process equipment or processes with the help of radiotracers. Whilst today diagnosis with radionuclides is quite commonplace in any major hospital, radiotracer techniques are used but rarely, if at all, in apparatus and process engineering.
Kinetik der Kohlen‐Pyrolyse als Grundlage für die Auslegung technischer Reaktoren
Authors: Van Heek Karl Heinrich
Published: December 2004

Kinetics of coal pyrolysis as a foundation for the design of technical reactors. The pyrolysis of coal is understood to mean its thermal decomposition at temperatures above 300°C, affording tar and char. It is the basic process underlying coking and the starting reaction of combustion, gasification, and hydrogenation. In addition, pyrolysis offers a means of converting coal into gases and liquids in a „third way”︁ besides gasification and hydrogenation. In order to establish a basis for the design of relevant technical reactors, the kinetics of coal pyrolysis has been investigated as a function of temperature and rate of heating and recently of pressure under inert gases and hydrogen. In particular, the rates of formation and the yields of liquid and gaseous products and the alteration of the solid matter have been examined under pressures ranging from 1 to 100 bar and at rates of heating between 0.05 and 1 000 K/s. It is shown how product formation can be controlled by these parameters and how the experimental data can be applied to reactor design.
Das Auswaschen von Filterkuchen
Authors: Bender Wolfgang
Published: December 2004

Washing of filter cakes. The demands placed on the purity of filter cakes exert a pronounced influence on investment and operating costs. Hence a careful study of the washing process is called for. On washing with a medium flowing through the cake it is possible to distinguish three regimes, viz. displacement, intermediate, and diffusional. The amount of washing liquid can be reduced by countercurrent operation, in several steps with repeated stirring of the cake in cases of extreme purity requirements. The washing results in an industrial plant are generally poorer than in the laboratory. The reasons for this discrepancy are more pronounced irregularities in the cake structure, cracking, or an inappropriate distribution of washing liquid.
Einsatz tomographischer Meßverfahren für verfahrenstechnische Untersuchungen
Authors: Mewes Dieter , Ostendorf Wilfried
Published: December 2004

Use of tomographic measuring techniques for process engineering studies. Tomographic measuring techniques have so far been employed almost exclusively in medicine and for testing of materials. They permit determination of experimental values for all local coordinates of a given volume at a given time. Classical tomography can be used for measurements only in stationary fields of flow, temperature, and concentration since the object has to be irradiated from as many directions as possible during a finite time interval. In the case of transient events, however, it is necessary to acquire all these values at the same point in time. If transparent fluids are present then coherent light is suitable for irradiation and holographic interferometry for recording the measured values. Since irradiation must take place simultaneously from several directions, the number of recording angles should be kept to a minimum. It is also necessary to employ mathematical procedures for image reconstruction in order to ensure adequate accuracy of the measured values.
Thermisches Hydrocracken von Kohlenwasserstoffen
Authors: Hedden Kurt , Weitkamp Jens
Published: December 2004

Thermal hydrocracking of hydrocarbons. Thermal hydrocracking or hydropyrolysis processes are currently under development in various modifications for upgrading of heavy oils. The present investigation examines thermal hydrocracking of pure model hydrocarbons. Typical petroleum hydrocarbons, i.e., alkanes, naphthenes, and aromatics were employed. At elevated conversions, alkanes and naphthenes are transformed predominantly into C1‐through C3‐alkanes. Ethane is the main product. In alkylaromatics the side chain is cracked exclusively up to high conversions. Therefore, dealkylated aromatics can be obtained in high yields as intermediate products.
Reaktionstechnische Grundlagen zur Auslegung und zum Betrieb von Bioreaktoren, Teil 1
Authors: Schügerl Karl
Published: December 2004

Reaction engineering fundamentals relating to design and operation of bioreactors. This review considers the reaction engineering foundations needed for the design and operation of bioreactors: mass and energy balances, thermodynamic data, reaction kinetics, reaction kinetic modelling, reactor models, and the combination of reaction kinetic models and reactor models.
Fortschritte in den wissenschaftlichen Grundlagen zur Auslegung von Kontakttrocknern für grob‐ und feinkörniges, rieselfähiges Trocknungsgut
Authors: Schlünder Ernst‐Ulrich
Published: December 2004

Advances in scientific fundamentals relating to the design of contact dryers for coarse‐ and fine‐grained flowable feeds. Curves depicting the course of drying which used in the design of contact dryers for flowable feeds can be calculated completely, except for a so‐called mixing quality factor, with the aid of known physical characteristics. Drying curves for individual grains are not necessary. The quality of mixing factor depends upon the kind of dryer, the flow properties of the product, and the intensity of the mixing motion. Its numerical value lies between about 2 and 25.
Biologische Abluftreinigung
Authors: Brauer Heinz
Published: December 2004

Biological purification of exhaust gases. The biological purification of exhaust typically employs microorganisms to transform undesired components, particularly those with pronounced odours into innocuous products. Since the activity of these organisms is localized in water, the odiferous substances must be transferred from the air to water. Oxygen must also be supplied to the water for product transformation. Large scale plant for biological purification of waste air from agricultural and industrial operations were introduced in Europe in the early 1960's. Since then this new technology has undergone remarkable developments. The principal plant types are biofilters, dripping units, and bioscrubbing units. In compost production and agriculture there is a current preference for biofilters and drip units, while biofilters and bioscrubbers are preferred in industry. Such plant already largely satisfy demands on purification performance and reliability. Further development in the direction of even higher performance and more compact plant is expected.
Die Bedeutung der Biotechnologie für die industrielle Chemie
Authors: Harnisch Heinz , Wöhner Gerhard
Published: December 2004

The significance of biotechnology for industrial chemistry. In the next few decades biotechnology will bring about fundamental innovations in the fields of health, nutrition, and agriculture as well as in important branches of industrial production, such as chemistry, which may well be comparable in importance with the present revolutionary technical progress based on electronics. Justification for these forecasts comes mainly from pioneering scientific advances in the fields of molecular biology, biochemistry, and microbiology. Particular mention should be made here of the fascinating potential of genetic engineering methods presently undergoing rapid development. However, less spectacular techniques, such as cell fusion and the immobilization of enzymes or whole living cells on polymeric substrates to give manageable, long‐lived biocatalysts, will also contribute to this wave of innovation. Some of these new developments are now gaining acceptance in industrial production.
Hydraulische Belastungen von Kesselreaktoren
Authors: Kipke Klaus Dieter
Published: December 2004

Hydraulic loading of tank reactors. According to the present knowledge, the hydraulic loading of agitators, reactors, and internals can be summarized as follows: Hydraulic forces can be represent in dimensionless form with the aid of force coefficients. In the turbulent regime, the load comprises an average value and a fluctuating component. In the case of gasifying reactors, the entire tank can undergo resonance vibration, which can, however, be estimated in advance. Gassing has a subordinate effect upon the hydraulic shaft loading. Strouhal effects may have to be considered with various internals. Resonance effects have already by observed in practice.
Probleme der Modellbildung bei technischen Festbettreaktoren
Authors: Eigenberger Gerhart , Ruppel Wilhelm
Published: December 2004

Problems and potential of mathematical modelling for industrial fixed‐bed reactors. Modelling and computer simulation for the purpose of design and operation of industrial fixed‐bed reactors are discussed with the aid of examples. Emphasis is placed upon difficulties and problems arising from the adequate model formulation. The following aspects are discussed in some detail: (1) The influence of heat and mass transport in the catalyst pellet, especially with complex reaction. (2) The relations between radial heat transfer and radial flow profile and its influence upon the axial temperature profile in packed tubes with or without heat generation by reaction. (3) The modelling of activity‐variations along the packed bed during the lifetime of a catalyst. (4) The scale‐up problem of multitubular fixed‐bed reactors, i.e. the problem of achieving and maintaining equal operating conditions inside and outside all the tubes of the bundle.
Zur Ermittlung von Stoffübergangszahlen auf der Basis von Gelöstsauerstoff‐Messungen
Authors: Schumpe Adrian
Published: December 2004

Determination of mass transfer coefficients on the basis of dissolved‐oxygen measurements. Sources of error in the dynamic and the stationary method for determination of mass transfer coefficients are discussed on the basis of experimental results obtained in bubble columns. In particular, the delayed electrode response, the resistance in the liquid film, bubble contacts of the electrode, and the influence of very small bubbles encountered in viscous media have to be considered.
Membranen in der Verfahrenstechnik
Authors: Strathmann Heiner , Chmiel Horst
Published: December 2004

Membranes in chemical engineering. In the last 10 years membranes and membrane processes have evolved from a useful laboratory tool to an industrial product of significant technical and commercial impact. In some applications membrane processes have today not only replaced some conventional separation procedures in the chemical process industry, because they are often more economical and yield better quality products, but they have also successfully been utilized to solve mass separation problems where conventional procedures failed or are too expensive. This contribution discusses the state of the art of membranes and membrane processes as well as their major applications, with the main emphasis being placed on more recent developments.
Exergoökonomische Bewertung einer Luftzerlegungs‐Anlage
Authors: Knoche Karl Friedrich , Hesselmann Klaus
Published: December 2004

Exergoeconomic evaluation of an air‐fractionation plant. This article presents a method for minimization of capital investment and energy costs for process plants. To this end the operating parameters are divided into two groups, i. e. into those affecting only the operation of individual components or groups of components and those of importance for operation of the entire plant. Optimization can therefore be undertaken in two steps: (1) optimization of plant components or group of components with regard to the operating parameters of the first group, (2) optimization of the entire plant with regard to operating parameters of the second group. This approach is illustrated by investment cost/exergy loss diagrams.
Pumpen und Verdichter für hohe Drücke — Festigkeit, Dichtungen, Verschleiß
Authors: Vetter Gerhard
Published: December 2004

Pumps and compressors for high pressures – strength, seals, wear. In high pressure processes pumps and compressors are used for the pressure range of 100 to 4 000 bar. Very careful design is necessary because of the extreme mechanical demands. The special features of high pressure technology are explained. The methods used for generating high pressures – displacement or fluid flow machine – impose design limitations, partly by the final temperature, Mach number, material fatigue, or vibrations. A survey of typical high pressure pumps and compressors shows the range and limitations of application. There is a definite trend to leak‐free systems. The best design of thick‐walled components with pulsating pressureload avoids grooves, requires smooth surfaces, and uses tough, clean, and high‐strength steels. The various designs of dynamic seals are explained and the state of the art is depicted. Detailed reference is also made to the exceptionally difficult wear problem of oscillating pump valves with abrasive suspensions.
Informationsaufgaben bei der Anlagenplanung
Authors: Lang Gerhard
Published: December 2004

Information policy in planning of plant. An account of the principal concepts of plant planning is followed by a description of the relationship between operator, planner, and periphery with their respective tasks and requirements. Execution of the tasks requires not only purposeful coordination of various engineering disciplines by the planner for mastery of technical questions, but also mastery of a complex organization to satisfy various information requirements of all institutions participating in plant planning. The planning results are divided as the output of individual planning functions into information categories with their data elements. Methods are presented for managing the rapidly swelling flood of information involved in planning with increasing demands on productivity, quality, and comprehensibility.
Expertensysteme – ein Hilfsmittel der Prozeß‐Synthese
Authors: Erdmann Hans‐Horst , Lauer cand. Inf. Michael , Passmann Michael , Schrank Eva , Simmrock Karl Hans
Published: December 2004

Expert systems for process syntheses. Commercial programs used in computer‐aided development of chemical processes need a process flowsheet as starting point. Preparation of flowsheets is based largely on human experience, an uncertain kind of knowledge expressed by heuristic rules. These rules are recognized as true and advantageous in most cases without having the validity of a law. Logic programming languages derived from research on artificial intelligence are proven tools for handling heuristics with so‐called “expert systems”. The flowsheets proposed by the expert system reduce all theoretically possible results to a few structures. The example of structuring distillation sequences illustrates what can be expected using an “expert system” in the area of “problem solving” by comparing its proposed sequences with optimized problems.
Koaleszenzprobleme in chemischen Prozessen
Authors: Berger Rosemarie
Published: December 2004

Coalescence problems in chemical processes. Separation of liquid/liquid dispersions is a process step which often gives rise to considerable difficulties on an industrial scale. A number of selected examples taken from chemical processes demonstrates where phase separations occur, the consequences they may have, and what industrially practicable methods are available for their solution. The problem analysis presented starts from the mechanism of generation of the dispersion and leads to a qualitative characterization of the various coalescence problems without presuming any knowledge of the droplet spectrum. This procedure acquires important knowledge from an assessment of prior process steps. Measures for improvement are deduced from the causes of poor phase separation: modification of physical properties, change of dispersion, use of mechanical separation aids (packings, coalescing filters), application of an electrical field, centrifuges and hydrocyclones, coalescence‐promoting chemical additives. Industrially applicable methods are reported for design of equipment for implementation of these approaches.
Die Bedeutung von Spalten zwischen Rohren und Rohrboden für das betriebliche Verhalten von Wärmeaustauschern
Authors: Achten Norbert , Herbsleb Günter , Wieling Norbert
Published: December 2004

Importance of crevices formed between tubes and tube plate for the operational behaviour of heat exchangers. It must be guaranteed by construction and manufacture of heat exchangers that primary and secondary medium are completely separated from each other. When this requirement is fullfilled, the operational use of heat exchangers can be impaired by corrosion reactions within the crevice formed between tube and tube plate which may result in corrosion damage. The various techniques which are in use to connect tubes and tube plate and which are described in the present report, must be valued with respect to the tightness of the connection as well as to the formation of crevices between tubes and tube plate. Corrosion resistant copperbase alloys and stainless steels are the most important materials which are in use for the construction of heat exchangers. The mechanisms of crevice corrosion with unalloyed and low alloy carbon steels, stainless steels, and mixed connections between tube and tube plate with these materials are described in detail. Crevice corrosion may be caused also by the formation of galvanic cells between materials of differing electrochemical response. Furthermore, the concentration of aggressive media in crevices between tubes and tube plate can lead to corrosion damage of heat exchanger tubes. For the service operation of heat exchangers without any hazard of corrosion damage in crevices between tubes and tube plate, such crevices must be avoided by proper construction and manufacture. As a model for suitable measures to avoid crevices, the manufacture of steam generators for PWR's is described.