bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternative Kraftstoffe: Chancen und Aufgaben
Authors: Seiffert Ulrich , Held Wolfgang
Published: December 2004

Die Verfügbarkeit von fossilen Energie‐Trägern ist begrenzt. Die Automobil‐Industrie bemüht sich, durch folgende Maßnahmen zur Einsparung und Substitution von Rohöl beizutragen: 1. Verringerung des Kraftstoffverbrauchs durch Optimierung des Fahrzeuges (Gewicht, Aerodynamik), Motor und Getriebe sowie Motor/Getriebe‐Management. Es werden hierzu zukünftige Entwicklungsmöglichkeiten vorgestellt. 2. Einsatz von alternativen Kraftstoffen. Es werden die verschiedenen Möglichkeiten des Einsatzes alternativer Kraftstoffe miteinander verglichen und bewertet. Recht aussichtsreich erscheint der Einsatz von gasförmigen (LPG) und flüssigen Kraftstoffen (Methanol und Ethanol), bei denen sich die noch offenen technischen Fragen mittelfristig lösen lassen. Es werden Fahrzeugkonzepte für den Reinalkohol‐ und Alkoholmischkraftstoff‐Betrieb vorgestellt und erste Versuchsergebnisse mitgeteilt.
Arbeitsstättenverordnung — Arbeitsstättenrichtlinien und ihre Auswirkung auf die Planung von Chemieanlagen
Authors: Bender Werner , Kaufmann Wolf Dietmar
Published: December 2004

Früher wurde die Auslegung von Chemieanlagen überwiegend von den technischen und chemischen Anforderungen des Verfahrens bestimmt. Heute sind noch viele andere Randbedingungen zu beachten, so auch die Arbeitsstättenverordnung (ASV) und die Arbeitsstättenrichtlinien (ASR). In einer kurzen Übersicht wird auf den Aufbau und die Zielsetzung der ASV eingegangen, sowie aufihre Einbindung in das Konzept des Bundesministeriums für Arbeit und Sozialordnung (BMAS) zur Fortentwicklung des technischen Arbeitsschutzes. Zu den ergänzenden ASR wird der aktuelle Stand dargestellt. Am Beispiel der Konzeptfindung für eine neue Chemieanlage wird gezeigt, welche Anforderungen der ASV und ASR das Verfahren, die bauliche Ausführung und die technischen Einrichtungen wesentlich beeinflussen. Abschließend wird auf Probleme eingegangen, die beim Zustandekommen, bei der Auslegung und bei der Anwendung der ASV und ASR auftreten.
Stand und Entwicklungstendenzen des konstruktiven Einsatzes von Kunststoffen in Chemieanlagen
Authors: Neitzel Manfred
Published: December 2004

Apparate und Rohrleitungen aus Kunststoffen werden in Chemieanlagen bis 150°C oder bei Drücken bis zu 16 bar eingesetzt. Mit der Kombination von hochkorrosionsbeständiger Innenschicht aus Thermoplasten und tragender Glasfaserkunststoff‐Struktur lassen sich zusätzlich Verbundkonstruktionen mit erweitertem Einsatzbereich herstellen. Probleme ergeben sich nur durch die Verarbeitungstechnik, wie an einigen typischen Schadensfällen gezeigt wird. Zur. Qualitätssicherung fehlen noch ausgereifte Methoden der Fehlerbestimung und Bewertungskriterien. Das Einhalten bzw. Durchsetzen entsprechender Richtlinien ist daher eine wesentliche Zukunftsaufgabe. Eine Gegenüberstellung der technischen und wirtschaftlichen Vor‐ und Nachteile von Rohrleitungen und Apparaten aus Kunststoffen läßt jedoch die positiven Entwicklungstendenzen des Einsatzes in Chemie‐Anlagen klar erkennen.
Anwendung experimenteller Labormodelle bei der Voraussage der Leistung von Gas/Flüssigkeits‐Reaktoren
Authors: Laurent André , Charpentier Jean‐Claude
Published: December 2004

Das Ziel dieser Arbeit ist es, Wert und Nutzen der experimentellen Simulation von Labormodellen bei der verfahrenstechnischen Auslegung von industriellen Gas/Flüssigkeits‐Reaktoren hervorzuheben. Der Begriff „Simulation”︁ wird definiert, und die bei dieser Methode notwendigen Kenngrößen werden hergeleitet; die verschiedenen Laborapparate, die als Modelle in Frage kommen, werden vorgestellt; für jeden von ihnen werden die Bereiche der oben genannten Kenngrößen angegeben, so daß es möglich wird, das für die Simulation eines gegebenen industriellen Gas/Flüssigkeits‐Reaktors brauchbare Labormodell auszuwählen. Die Prinzipien der differentiellen (mit einem „Punktmodell”︁) und der integralen Simulation (mit einem „vollständigen”︁ Modell) werden dargestellt. Einige praktische Beispiele werden gegeben; auf zwei Anwendungen wird näher eingegangen: die differentielle Simulation einer Füllkörperkolonne mit einem Labor‐Rührkesselreaktor und die integrale Simulation eines Venturi‐Flüssigkeitsstrahlwäschers durch einen laminaren Strahl. Schließlich werden die bis jetzt veröffentlichten industriellen Anwendungen dieser Simulationsmethode vorgestellt.
Biologische Abwasserreinigungsanlagen
Authors: Leistner Gerhard , Müller Gerhard , von Rüden Ferdinand
Published: December 2004

In biologischen Abwasserreinigungsanlagen werden die im Abwasser gelösten organischen Schmutzstoffe durch Bakterien abgebaut. Für den aeroben Stoffwechselprozeß der Bakterien sind dem Abwasser Sauerstoff und gegebenenfalls Nährstoffe zuzuführen. Für die Belebungsstufe der biologischen Abwasserreinigungsanlagen ist besonders im industriellen Bereich die Abkehr von den mit Oberflächenbelüftern ausgestatteten Flachbeckenanlagen (3 bis 4 m Wasserhöhe) und die Hinwendung zu größeren Wassertiefen, die unter Wasser installierte Druckbelüftungssysteme erfordern, festzustellen. Jüngste Entwicklungen sind durch Hochbauweise (Tankbau) mit Wasserhöhen zwischen 15 und 30 m oder durch unterirdische Einrichtungen (ca. 100 m tief gehende Rohre) gekennzeichnet. Hierfür wird das Bestreben ausschlaggebend, die Abluftmengen zu reduzieren, Platz einzusparen, Geruchs‐ und Lärmprobleme zu vermindern und möglichst Investitions‐ und Energiekosten einzusparen. Zur Steigerung der Raum‐Zeit‐Ausbeute, zur besseren Beherrschung von stoßartigen Belastungen und zur Erhöhung des Abbaugrades wird der verfahrenstechnischen Prozeßführung gesteigerte Aufmerksamkeit gewidmet, indem man bewußt den volldurchmischten Reaktionsraum, die Kaskadenfahrweise oder die Rohrcharakteristik anstrebt. Neben Luft wird die Begasung mit reinem Sauerstoff angewendet. Für besonders kritische Abwässer kommt Aktivkohle in pulverisierter oder körniger Form zum Einsatz. Für Stickstoff enthaltende Abwässer wird eine Denitrifizierungsstufe zugeschaltet. Derzeit relevante Verfahren und Anlagen werden betrachtet.
Methodik beim Extrapolieren chemischer Reaktoren
Authors: Trambouze Pierre
Published: December 2004

Obwohl die Notwendigkeit einer systematischen Vorgehensweise bei der Maßstabsvergrößerung von Reaktoren in mehreren Veröffentlichungen betont wird, wird dies leider nicht immer hinreichend beachtet. Die Methodik bei der Maßstabsvergrößerung betrifft nicht nur den chemischen Reaktor selbst, sondern auch alle wesentliche Komponenten eines chemischen Verfahrens. Im folgenden wird ausschließlich die Maßstabsvergrößerung von Reaktoren behandelt, weil die Extrapolation der Reaktoren die größten Schwierigkeiten bereitet. Nach der Beschreibung der Vorgehensweise wird anhand einiger praktischer Beispiele gezeigt, wie die Methodik angewendet werden kann.
Genetik: Aufgaben, Möglichkeiten und Grenzen in der Biotechnologie
Authors: Esser Karl
Published: December 2004

Ausgehend von der Tatsache, daß der wirtschaftliche Wert eines biotechnologischen Verfahrens in wesentlichem Maße von der Leistung des betreffenden Mikroorganismus abhängig ist, besteht die Aufgabe der Genetik darin, durch entsprechende Manipulationen den Ertrag zu steigern und ein einmal erreichtes Produktionsniveau zu erhalten. Nach Besprechung der verschiedenen experimentellen Möglichkeiten wird anhand von drei Beispielen aufgezeigt, auf welche Weise Erkenntnisse der Grundlagenforschung in der Biotechnologie verwendet werden können. Beim ersten handelt es sich um die Produktion von Einzeller‐Protein, ein Problem, das von der Industrie an die Grundlagenforschung herangetragen wurde. Im zweiten Beispiel wird die genetische Kontrolle der Fruchtkörperbildung holzabbauender Pilze erörtert, eine Fragestellung der Grundlagenforschung, die aber nach Aufklärung der betreffenden Genmechanismen eine Rückstrahlung in die Biotechnologie hat, vor allem für Recycling‐Prozesse. Beim dritten Beispiel geht es um die Seneszenz, ursprünglich ebenfalls ein Problem von theoretischem Interesse, das jedoch in den letzten Jahren für die Fermenterindustrie an Bedeutung gewonnen hat (z. B. Nachlassen der Produktivität von Industriestämmen). Die Verfolgung dieser Fragestellung hat zu einer Entdeckung von plasmidähnlicher DNA geführt und damit ein neues Feld für die Grundlagenforschung eröffnet, denn es gibt nunmehr eine reale Möglichkeit, die bisher bei Bakterien durchgeführten Klonierugen auch auf Hyphenpilze auszudehnen. Damit ist ein neues genetisches Potential für die praktische Anwendung aufgezeigt. Abschließend wird auf die Grenzen für den Einsatz genetischer Methoden in der Biotechnologie hingewiesen, und zwar unter Berücksichtigung von (1) Koexistenzschwierigkeiten von Erbinformationen nahe verwandter Organismen, (2) der Unfähigkeit von Zellen, nach Erhalt fremder genetischer Information ein stabiles Produkt zu produzieren, und (3) der Stabilität genetischer Information nach erfolgter Hybridisierung.
Stand der thermohydraulischen Kenntnisse bei Druckentlastungsvorgängen
Authors: Mayinger Franz
Published: December 2004

Bei der Berechnug der Druckentlastung, z. B. für die Auslegung von Sicherheitsventilen, spielen Siedeverzug, Aufschäumen durch Entspannungsverdampfung, Phasenseparation, kritisches Ausströmen sowie die thermo‐ und fluiddynamische Kopplung von Apparatekomponenten und ‐Gruppen eine Rolle. Kenntnisse über diese physikalischen Vorgänge sind in ausreichendem Maße nur für Wasser aus Untersuchungen zum Störfallverhalten von Kernkraftanlagen vorhanden. Es wird der Stand der Kenntniss über diese fluiddynamischen Vorgänge diskutiert, unter Einschluß von Rechenprogrammen, welche den zeitlichen Druck‐ und Füllstandsverlauf auch im Apparateverbund analysieren lassen. Wege zur Anwendung und Übertragung der thermohydraulischen Kenntnisse auf Chemieanlagen werden aufgezeigt.
Einsatzkriterien für textile Filtermedien
Authors: Bremus Hermann‐Josef
Published: December 2004

Es werden die chemischen, thermischen und mechanischen Anforderungen beschrieben, die bei der Auswahl eines Filtermediums, bezogen auf die heutigen für Filterzwecke verarbeiteten, synthetischen Faserarten, für die verschiedenen Verfahren in der Naß‐ und Trockenfiltration berücksichtigt werden müssen. Hierbei wird auch der Einfluß des textiltechnischen Aufbaues der Filtermedien in Pore und Masche und deren Auswirkung auf die Filterwirksamkeit dargestellt. Die Anforderungen an die Konfektionierung werden anhand der für textile Abscheider möglichen Fügeelemente erläutert.
Verfahrenstechnische Kriterien bei der Auswahl von Flüssigkeitspumpen
Authors: Leuschner Günter
Published: December 2004

Von den Flüssigkeitspumpen in verfahrenstechnischen Anlagen wird ein Höchstmaß an Betriebssicherheit und Verfügbarkeit erwartet, denn „kritische”︁ Pumpen können bei Ausfall ganze Anlagen außer Betrieb setzen und durch Produktionsunterbrechungen oft kaum abschätzbare Kosten verursachen. Es werden daher einige wesentliche Gesichtspunkte für die richtige Auswahl dieser Pumpen aufgezeigt, unter Einbeziehung von Betriebsverhalten und Einsatzgrenzen, wobei verfahrenstechnische Kriterien im Vordergrund stehen. Wirtschaftliche Überlegungen können in diesem Rahmen nur kurz angesprochen werden.
Zum Stand der Extraktion mit komprimierten Gasen
Authors: Brunner Gerd , Peter Siegfried
Published: December 2004

Gase unter hohem Druck haben die Eigenschaften von Lösungsmitteln. Ihre Verwendung führt zu neuartigen Trennverfahren, die die Verfahrenstechnik der Stofftrennung um eine Gruppe neuer Verfahrensweisen erweitern. In der chemischen Reaktionstechnik können Katalysatoren in Gasphasen hoher Dichte gelöst und dadurch günstige Reaktionsbedingungen bewirkt werden.

In der Nähe der kritischen Temperatur werden bei relativ mäßigen Drücken im Bereich von 50 bis etwa 300 bar bereits flüssigkeitsähnliche Dichten des komprimierten Gases erreicht. Es ergibt sich eine vergleichsweise hohe Lösefähigkeit der gasförmigen Phasen. Diese Eigenschaft eines komprimierten Gases kann durch Ändern von Druck und Temperatur in weiten Grenzen variiert werden. Mit abnehmender Dichte nähert es sich dem Verhalten eines normalen Gases, mit zunehmender Dichte dem einer Flüssigkeit. Somit ergibt sich die Möglichkeit, die gelösten Stoffe wieder auszufällen. Durch die kritische Temperatur des verwendeten Gases ist die Arbeitstemperatur eines solchen Verfahrens weitgehend festgelegt. Da eine Reihe leicht verfügbarer Gase kritische Temperaturen im Bereich bis 50°C besitzen, wurde bei Entwicklung dieser Verfahren zunächst die Trennung temperaturempfindlicher und schwerflüchtiger Stoffmischungen behandelt. Darüber hinaus versprechen polare Stoffe mit erheblich höher liegenden kritischen Temperaturen wie Ammoniak, Methanol und Wasser eine Reihe weiterer Anwendungsmöglichkeiten.
Moderne Verfahren zur Berechnung des Strahlungsaustausches in brennstoffbeheizten Röhrenöfen
Authors: Scholand Elmar
Published: December 2004

Neben den einfachen null‐ bis zweidimensionalen Modellen zur Berechnung des Wärmeaustausches durch Strahlung in Feuerräumen haben vor allem die Zonemethode nach Hottel, die Monte‐Carlo‐Methode und die Flußmethode besondere Bedeutung erlangt. Alle drei Methoden eignen sich für dreidimensionale Verhältnisse. Dabei sind die beiden erstgenannten Verfahren als mathematisch exakt anzusehen, während die Flußmethode ein Näherungsverfahren ist. Am Beispiel eines Röhrenofens wird aber gezeigt, daß sich mit einer nulldimensionalen Methode in vielen Fällen der Wärmefluß durch Strahlung an die Rohrbündel mit ebenso guter Genauigkeit bestimmen läßt.
Instandhaltungsgerechte Gestaltung technischer Anlagen
Authors: van Laak Heinrich
Published: December 2004

Maintenance‐favourable design of industrial plant. A study by the German Maintenance Committee proves that maintenance costs in the Federal Republic in 1977 amounted to 123 × 109 DM, of which 30 × 109 DM were accounted for by manufacturing industry and more than 5 × 109 DM by the chemical industry. Over 50% of subsequent damage costs are caused in the planning and manufacture phase. These sources of damage become manifest during later use and damage and secondary damage costs are incurred by the user. An appeal therefore goes out to plant manufacturers, users, and maintenance staff to cooperate in reducing the sources of damage. An important basis for such a move is the collection and exchange of data, utilization of data pools, and systematic analysis for determination of weak points at the planning and construction stage. Since maintenance costs, as one of the four operational cost factors (material, personnel, energy, and maintenance costs), show an increasing tendency with progressive automation there is a continuiing need for a cost or profit center for plant engineering or planned maintenance.
Wasserstoff‐Energiewirtschaft aus kritischer Sicht
Authors: Wicke Ewald
Published: December 2004

A critical view of the hydrogen economy. The goal of the hydrogen economy is to replace electrical energy, petroleum products, and natural gas wherever feasible by hydrogen as secondary energy. Apart from the coal the only primary energy source which be available in the near future will be nuclear energy, preferentially for supplying process heat for coal gasification (high temperature reactor). There will hardly be a future for thermochemical cyclic processes for cleavage of water; development of electrolytic process utilizing electrical energy from nuclear reactors appears technically and economically more promising. Exploitation of solar energy for generation of hydrogen appears unlikely in this century. The original concept of the hydrogen economy was associated with the discovery of hydrides of intermetallic compounds which are suitable for reversible storage of hydrogen. During the ensuing 15 years since the pioneering studies on this topic extensive detailed knowledge has accrued about the thermodynamic behaviour of hydride storage systems, their lattice structure, and the uptake and release of hydrogen. In any case, the hydrogen economy will be expensive with regard to both development and the necessary investment in this application.
Wärme‐, Stoff‐ und Impulsübertragung in abgelösten Strömungen
Authors: Kottke Volker
Published: December 2004

Heat, mass and momentum transfer in separated flows. The simple model of a backward‐facing step in flat plate boundary layers provides basic information on heat, mass and momentum transfer in local separated regions. These new investigations cover nearly the whole range of existence of incompressible separated flows with laminar as well as turbulent boundary layers at separation, including the two main parameters Reδ1 and Res: The Reynolds number Reδ1 represents the boundary layer at separation, the Reynolds number Res the shape of the body. It is demonstrated that independently of the state of the boundary layer at separation, there exist three types of local separated regions. Therefore a new general valid classification of local separated flows is introduced based on the actual state of the separated boundary (shear) layer from separation to reattachement. The new results presented are limited to the case where no temperature or concentration boundary layers exist at separation, i.e. to the case of unheated or inert starting length before separation: Only then can the analogy of heat, mass and momentum transfer give useful results over the whole range of existence of local separated regions. A new shear layer model is introduced to facilitate transfer of the results obtained for backward‐facing steps to arbitrary shaped bodies. A compilation and comparison of available literature values shows that this shear layer model for the step also permits the calculation of heat and mass transfer in separated areas on arbitrarily shaped bodies.
Gewinnung leichter Kohlenwasserstoffe aus schweren Ölen — Verfahren und Entwicklungen
Authors: Weitkamp Jens
Published: December 2004

Manufacture of light hydrocarbons from heavy oils – processes and developments. High quality crude oils are running short and their price continues to increase. At the same time there is a trend towards light petroleum products for use as transportation fuels or petrochemical raw materials. Consequently, the conversion of heavy oils, i.e., particularly distillation residues but also heavy oils from tar sands, is gaining increasing commercial importance. The cracking processes currently used in the refining industry are reviewed. Emphasis is placed on their application to metal‐and asphaltene‐containing heavy oils. Feed pretreatment by solvent deasphalting is discussed and the manufacture of syncrude from tar sands is considered. New developments for conversion of heavy oils are outlined. The future production of shale oil and of transportation fuels from oil shale is briefly treated.
Herstellung von Fahrbenzin aus Kohle oder Erdgas
Authors: Cornelius Gerhard , Hilsebein Wolfgang , Supp Emil
Published: December 2004

Production of petrol from coal and natural gas. This article assumes an adequate knowledge of the Fischer‐Tropsch process in its original form and as its modern variant, the Synthol process, and adopts the view that coal hydrogenation will only become implementable on an industrial scale in the early 1990. In detail, it considers the integration of the Mobil MTG process in the proven area of methanol production; operation of pilot plant has shown that this process is indeed suitable for industrial scale operation. The production of methanol from natural gas and coal is discussed, as is the subsequent conversion of methanol to petrol; emphasis is placed on the best possible integration of all process plant. Apart from the conventional steam reforming route for methanol production from natural gas, the alternative approach of combing a steam reforming plant with an autothermal cleavage step is also considered; the latter leads to a significant increase in efficiency and a reduction in investment costs. It is also shown for coal as raw material that simultaneous generation of petrol and SNG has considerable advantages of a thermal and financial nature. The principal process steps are described after the manner of keywords and the product costs are presented as functions of the various raw material costs.
Trend in der Rektifiziertechnik: Energie‐Einsparung
Authors: Schlüter Lothar , Schmidt Rudolf
Published: December 2004

Present tendency in rectification: energy economizing. Rectification columns are the greatest consumers of energy in many chemical plants. Decreasing their energy consumption has been a long term aim in process engineering. These considerations have culminated, for example, in the splitting of a separation between two columns operating at different pressures to make an energy match feasible, the application of heat pumps, of intermediate evaporators and condensers, and also the joint execution of different separations in one column with several feeds and side streams. These ideas were formerly often thwarted by high investment costs and (supposed) reduced flexibility; in recent years, however, the design of complex plants with extensive energy matching has become commonplace. A prerequisite is the feasibility of calculating sufficiently exactly the necessary separation units; moreover, there is also a need for efficient column intervals and heat exchangers which can operate with small pressure drops and modest temperature gradients. A general energy‐saving strategy also leads to process modifications in other separation techniques such as liquid‐liquid extraction.
Entwicklung von Kristallisatoren
Authors: De Jong Esso J.
Published: December 2004

Development of crystallizers. The control of the crystallization kinetics and the spatial variation of the crystal mass are of decisive importance for the operation of industrial crystallizers. The influence of micro‐ and macro‐attrition is demonstrated with particular reference to collisions with impeller blades and to breakage of crystals between impeller and draft tube. Spatial variations of supersaturation and crystal mass within the crystallizer have been shown to influence crystal size distribution. These variations are described by physical and mathematical models. Crystal size distributions measured in both pilot and industrial crystallizers show that simulation with the proposed models is very reliable. A model approach provides valuable support for the development of industrial crystallizers and also for the development of control using microprocessors.
Impuls‐ und Stoffaustausch in gasdurchströmten Schüttungen von Hochtemperatur‐Reaktoren und Schachtöfen
Authors: Kremer Hans , Rodenhäuser Fritz
Published: December 2004

Momentum and mass transfer in packed beds subject to gas flow in high‐temperature reactors and shaft furnaces. Dependable design of fixed and traveling bed reactors operating at high temperatures requires a detailed knowledge of heat and mass transfer at the solid surface and precise information about the pressure and gas velocity distribution inside the fixed bed. Special interest is focussed on the mixing of different component streams in some packed beds. The mixing depends on several parameters, such as particle size, bed length and diameter, configuration of junction points, and mass flow ratio of the individual gas streams. A general view summarizes our present knowledge of physical models of momentum and mass transfer and of mathematical descriptions of processes occurring in packed beds in terms of technical geometry (three‐dimensional array). In particular, possibilities of calculating the dispersion in complex packed beds through which flow take place are displayed. In this connection it is shown there are still some unsolved problems.
Gas‐Trennung mit Membranen
Authors: Schulz Günter , Michele Helmut , Werner Udo
Published: December 2004

Gas Separation with membranes. Gas separation with membranes has already been tested in numerous fields of application, e. g. uranium enrichment or H2 separation. In many of these processes the mass transfer units, so‐called permeators, have to be connected in tandem in order to achieve high concentrations. A most economical operating method provides for each case an optimization of the cascades with regard to the membrane materials, construction and design of module. By utilization of the concentration gradient along the membrane a new process development has been accomplished – the continuously operating membrane rectification unit. Investment and operating costs can be reduced considerably for a number of separating processes by combining a membrane rectification unit with a conventional recycling cascade. However, the new procedure requires that the specifications for the module construction, flow design, and membrane properties be reconsidered.
Offene Probleme in der Rührtechnik
Authors: Kipke Klausdieter
Published: December 2004

Open problems in stirring technology. In this article, an attempt is made to show those problems which still have to be solved largely by empirical methods. The list of problems is by no means complete, and many of them may still not be regarded as a problem by specialists. Nevertheless, the problems of stirring technology are shown in the framework of its development to date in order to indicate possible developments for the near future. Thus greater attention to fluid mechanics (turbulence, non‐Newtonian liquids, large volume flow) could be of advantage. Simplified model concepts which analytically describe at least part of the complex stirring and mixing process are desirable. Departure from frequently uncritical application of dimensional analysis and inclusion of flow mechanics and chemical engineering reasons for ensuring mechanical loads would help to solve many a problem.
Einsatzkriterien für Dekanter
Authors: Alt Christian , Gösele Walter
Published: December 2004

Criteria for the use of decanters. This survey intends to help the chemical engineer having no special prior knowledge to consider the development of a decanter and where appropriate to conduct design experiments with the aid of a producer and a hired machine. In compliance with the various stages involved in process design, the first section relates to general guidelines, the second one to laboratory experiments, and the third one to pilot experiments. The fourth section then summarizes the possible inferences of the individual experiments, and demontrates the gaps in our present knowledge.
Weitergehende Reinigung von Abwässern der Chemischen Industrie mit Hilfe von Aktivkohle
Authors: Eisenächer Karl , Neumann Ulrich
Published: December 2004

Further treatment of waste water in the chemical industry by use of activated carbon. Biological treatment has proved to be no longer adequate for numerous waste water streams emitted by chemical plants. Some of the pollutants entrained by the waste water feature poor biodegradability, and certain compounds even have a detrimental effect on the microorganisms of the activate sludge. Adsorption by activated carbon is one of the potential methods for eliminating such substances. Explanations refer to the physical phenomena of the process. Adsorption may be performed prior to or after biological treatment. Commercial‐scale plants use granular activated carbon and use an intermittent process (fixed bed) or a continuous process (countercurrent adsorber). Possibilities and aspects are exemplified by plants using this process. Operating results are presented. A recent development combines the biological and adsorptive treatment which is based on the continuous admission of powdered activated carbon into the activated‐sludge basin. Results obtained in a demonstration plant will be discussed. Cost‐effective application of this technology is, however, conditional upon reactivation of spent carbon.
Zyklonabscheider zum Trennen von Gas/Feststoff‐Strömungen
Authors: Bohnet Matthias
Published: December 2004

Cyclone separators for separation of gas/solids flow systems. Cyclones are used for separation of particles of solids from gas flow. Although cyclones have been in industrial use for nearly a century, it is still impossible to completely calculate the flow processes involved. This contribution deals with the theory of the separation process with separation behaviour, limiting particle size, generation of twist, and pressure drop. The article describes optimization of the cyclone by aerodynamic calculations with the separation performance, energy requirement, and investment costs as parameters. The separation performance and the energy requirements of cyclones are largely determined by the mode of construction and the operating conditions. Cyclones used industrially are discussed.
Luftversorgung bei Zweiphasenströmungen
Authors: Schmidt Paul
Published: December 2004

Air supply in binary flow. Air is used almost exclusively as the gas in gas/solids flow systems. At low pressure differences of a plant (Δp ≲ 0.5 bar) one speaks of air supply, and at higher pressure differences of compressed air supply. The machines used for supply of the air are fans or compressors. Their characterics should be as steep as possible in order to attain a stable working point in conjunction with the plant. Radial fans are used very frequently because they are inexpensive, reliable, and in some cases passable by the solids; however, they have unfavourable characteristics. Increasing use has recently been made of rotary piston and screw compressors; their characteristics are very steep. Attention must frequently be paid to preparation of the air, and especially drying. The cost of providing the air should be determined as accurately as possible for economic assessments.
Auslegung und Aufbau von Sicherheitseinrichtungen mit Mitteln der Meß‐, Steuer‐ und Regelungstechnik
Authors: Greiner Bernd , Weidlich Stefan
Published: December 2004

Design and construction of safety devices utilizing methods of measurement and control engineering. This article considers a proposed concept for the design and construction of measurement and control devices for the safety of plant with the aim of preventing danger to persons and the environment and damage. Such measurement and control devices are generally employed when primary measures adopted for plant safety, such as safety valves, collection vessels, etc. are not applicable or insufficient by themselves. The concept regards the new sheet no. 3 of the VDI/VDE code draft 2180 „Safety of chemical engineering plant”︁ and proposes a further subdivision of class A into safety classes A0, A1, and A2. Overall, it is possible, on the basis of the measures for raising the availability of measurement and control equipment which are presented in this article, to make selection appropriate to the potential danger involved. The proposed procedure should not, however, be regarded as a rigid scheme but rather as leading to a systematic view and supporting decisions resting on sound operating experience.
Ausbreitung explosibler Gaswolken in der Nähe von Anlagen der Chemischen Industrie
Authors: Kremer Hans
Published: December 2004

Propagation of explosive gas clouds in the vicinity of chemical plant. The propagation of large amounts of gases in the vicinity of industrial plant can lead to safety risks and must therefore be estimable in their effect. Methods of both theoretical and experimental simulation are available. Among the computational models, the conventional propagation models used in meteorology are suitable for free propagation. In cases of propagation close to buildings, the relatively straightforwardly applied binomial model is a better choice. Owing to the occurrence of turbulence, the calculations should be supported by wind tunnel studies. An unfavourable system leading to accumulation of large amounts of gas is seen to be a U‐shaped arrangement of buildings with incident flow on the convex side.
Kooperation von Technik und Recht im Hinblick auf die technische Sicherheit
Authors: Nicklisch Fritz
Published: December 2004

Cooperation between technology and legislation with regard to technical safety. Exploitation of technology involves risks. The state permits this exploitation and must therefore guarantee the necessary safety. In this context, legislation employs undefined legal concepts: „generally recognized rules of technology”︁, „state of technology”︁, „state of science and technology”︁. These standards located at the interface of law and technology raise the question of competence assignment between scientific and technical experts and the authorities and courts. The solution: decision by scientific‐technical experts on the basis of their expertise, coupled with review by the courts in order to establish whether the legal goal of „safety”︁ has been attained. The intermeshing between legal and technical standards is expressed in the technical standards.
Möglichkeiten der elektrochemischen Kohleumwandlung
Authors: Coughlin Robert W. , Kreysa Gerhard
Published: December 2004

Possibilities of electrochemical conversion of coal. Coal as a macromolecular organic substance can principally undergo electrochemical conversions. Presently three main directions are under investigation: electrochemical gasification with the formation of hydrogen and carbon dioxide; modification of the chemical composition of coal; and degradation to low‐molecular substances. A historical survey as well as the present state of the art is given and the electrochemical reactions of the coal and their mechanisms are discussed in detail.
Fischer‐Tropsch‐Synthese. Neuere Untersuchungen und Entwicklungen
Authors: König Lutz , Gaube Johann
Published: December 2004

Fischer‐Tropsch synthesis – Recent studies and Developments. This article surveys some results of recent research and new lines of development in Fischer‐Tropsch synthesis. Most interest is focussed on variants synthesis showing high selectivity of C2‐C4 alkenes or C5‐C20 1‐alkenes or Diesel oil. In the last decade catalysts of improved alkene selectivity have been developed. Also the dependence of selectivity on process parameters such as pressure of hydrogen and carbon monoxide and temperature has been investigated in order to find appropriate conditions of operation for a synthesis of high selectivity. Some preliminary process designs are discussed.
Partikelabscheidung an Tropfen und Fasern
Authors: Löffler Friedrich
Published: December 2004

Particle deposition on droplets and fibres. The fundamental processes involved in deposition on fibres and drops are discussed and theoretical model calculations are presented. It is shown that approximative equations and diagrams permit fast estimation of degrees of collision and extent of adherence. Experimental studies confirm the model calculations.
Automatisierung in der Verfahrenstechnik — Möglichkeiten und Grenzen
Authors: Nottebohm Harald
Published: December 2004

Automation in the chemical industry – scope and limitations. Tempestuous developments in semiconductor technology centering upon the microprocessor open up new possibilities of automation in chemical engineering. The traditional appearance of process control rooms is changing drastically. A few video display units with uniform keyboards suffice to monitor and control an extensive chemical plant. In spite of all technical perfection, automation has its limitations wherever unavoidable irregularities require human intervention. This in turn requires that one is in command of both the process and the function of the automatic mechanism.
Transporterscheinungen in Dreiphasen‐Reaktoren mit fluidisiertem Feststoff
Authors: Deckwer Wolf‐Dieter , Schumpe Adrian
Published: December 2004

Transport phenomena in three‐phase reactors with fluidized solids. Three‐phase reactors with fluidized solids have a wide range of application. It extends from catalytic hydrogenation, oxidations, polymerizations, and reactions of synthesis gas to coal liquefaction plant and applications in biotechnology. Considerable advantages of these reactors lie in the intense degree of contact between the phases and in their high thermal stability relative to other types of reactors. Pertinent model concepts of fluid dynamics are treated qualitatively, and our present knowledge about transport phenomena within and between the phases is reviewed. Modelling of these reactors is considered in conclusion.
Verfahren zur Entschwefelung von Rauchgas
Authors: Kaminsky Walter
Published: December 2004

Processes for flue gas desulphurization. The continuous high emission of sulphur dioxide from the combustion of fossil fuels is causing increasing damage not only to nature but also to buildings and machinery, especially in industrialized countries. It is possible by desulphurization of the flue gases to reduce the emission of sulphur dioxide by as much as 90%. This can be achieved industrially by dry absorption using activated charcoal or addition of limestone, and by wet processes employing soda, limestone, calcium hydroxide or ammonia as absorbents. The characteristic features of each of the different processes are described. The main residues obtained from these desulphurization processes are gypsum, sulphur, or fertilizer salts, most of which can be recycled. The running costs for such flue gas cleaning processes amount to between DM 0.007 and DM 0.018/kWh depending on location and requirements.
Neuere Sensoren zur Erfassung der klassischen MeßGrößen in der Verfahrenstechnik
Authors: Schneider Hans‐Josef
Published: December 2004

New types of sensors for determination of classical quantities. A description is given of those innovations in the field of flow, pressure, temperature, and level sensors which have appeared during the last ten years, and which have given satisfactory results on use in process engineering. Flow measuring methods are dealt with in particular detail because of their special significance. Finally, the report deals with semiconductor and ceramic sensors.
Neue großtechnische Anwendungen des Reaktionsprinzips der zirkulierenden Wirbelschicht
Authors: Reh Lothar
Published: December 2004

New industrial applications of the circulating fluidized bed. Strongly expanding fluidized beds in the boundary region between fluidized bed and pneumatic conveying, which can achieve a steady state only by recirculation of the solids are of considerable importance for environmental protection because of the high gas flow rates and the high relative velocities possible between gas and solids in performing reactions between gases and fines with an average particle diameter less than 300 μm. Lurgi has utilized the principle of the circulating fluidized bed industrially both in the high temperature regime for the non‐pollutive production of process heat from low‐grade coal in a plant of 84 MW thermal rating and in the low temperature regime for adsorptive, dry purification of fluorine‐containing waste gases from aluminium electrolysis and for dry removal of pollutants from garbage‐burning power plants. This paper reports on the new process.
Einfluß der Wandreibung auf die Dimensionierung von Bunkern — Verfahrenstechnische und statische Gesichtspunkte
Authors: Schwedes Jörg
Published: December 2004

Influence of wall friction on the design of silos – Aspects of process technology and statics.Mass flow and funnel flow are distinguished when considering the discharge of stored bulk solids. In order to cause mass flow to occur, i. e. the complete bunker filling is in motion, hopper walls need to be steep. Conditions close to the outlet are decisive, a large value of wall friction requiring steep hopper walls. For a safe design of bunker walls with respect to mechanical strength, DIN 1055, part 6 is commonly applied; it is currently being revised. From this regulation a strong influence of the angle of wall friction can be inferred, small values of the angle being associated with high horizontal pressures. In case the angle of wall friction depends on pressure and other parameters and safety factors are included there may be a considerable difference between the angle used by a process engineer and by a civil engineer.
Herstellung von Formkörpern mit definierter Porenstruktur
Authors: Hammon Ulrich , Kotter Michael
Published: December 2004

Fabrication of pellets with defined pore‐size distribution. The fabrication of porous alumina‐pellets of high mechanical strength and with a well defined pore‐size distribution by pelletization and by extrusion is described. Macropores can be introduced through solid material which is vaporized after agglomeration; the content of macropores can thereby be chosen within a rather wide range. The amount of micropores in the pellets can be controlled by thermal treatment (sintering). Mechanical strength is obtained if the primary particles are connected by bridges of solid material, generated from substances dissolved in the liquid which fills the pores before drying. The mechanism and the procedure leading to the formation of porous alumina‐pellets are also applicable if silica or zeolites are to be agglomerated into porous pellets of high mechanical strength.
Auslegung und Dimensionierung eines mechanischen Schaumzerstörers
Authors: Zlokarnik Marko
Published: December 2004

Design and dimensions of a mechanical defoamer. This paper presents a newly developed powerful mechanical defoamer which exploits centrifugal force and, thanks to circular channels, also Coriolis force for destruction of foam. It is incorporated into containers such that the expelled foam concentrate is deflected by the lid without producing fresh foam. Model experiments with three geometrically similar but different sized laboratory models led to dimensionaltheoretically formulated process‐relations of the defoamer for various material systems (five chemical foamers, two biological substrates). Such process‐relations represent a reliable basis for design and dimensions of the defoamer presented, on the one hand, and permit determination of an „intermediate characteristic”︁, having the dimensions of acceleration, which represents the mechanical degradability of the foam.
Methodische Entwicklung verfahrenstechnischer Prozesse
Authors: Blaß Eckhart
Published: December 2004

Methodological development of chemical engineering processes. The development of complex systems is especially dependent upon methodologically structured procedures to provide a clear‐cut framework for the application of specialist knowledge and creativity and to develop and exploit the field of possible solutions in order to single out a powerful solution. The method of choice should always be systems engineering. It provides, in relatively abtract and interpretable manner, principles, methods, and proven aids in the form of a system concept, a systems engineering plan of procedure, and project management. A brief introduction to the system concept is followed by application of the systems engineering procedural model to process development. Safety engineering and data acquisition are then considered in detail. Heuristic models are also considered in relation to data acquisition. Expert systems are recommended for setting up collections of information. The article closes with a survey of computer‐aided process development.
Stand und Trends bei der Entwicklung leckfreier oszillierender Verdrängerpumpen
Authors: Vetter Gerhard
Published: December 2004

Leakfree oscillating positive‐displacement pumps – state of the art and trends of development. Leak‐ and maintenance‐free oscillating positive‐displacement pumps are very important for avoiding pollution and improving the reliability of plants. Technical progress in the field of hydraulic diaphragm‐ and tube‐pumps for high pressures are explained. The actual data (pressure, efficiency, temperature) and experience with different fluids are surveyed. The various hydraulic control systems, the diaphragm design, and methods for rupture‐control are compared. Further development trends are explained.
Auslegung von Industrie‐Rührwerken
Authors: Kipke Klaus
Published: December 2004

Design of industrial agitators. The chemical engineering and mechanical design of industrial agitators has meanwhile developed into a highly complex process. Energy‐saving constraints no longer allow agitator scale‐up with P/V = constant while deriving the mechanical dimensions purely in terms of the torque. A clear classification of the various goals of agitation into the basic components with the corresponding scale‐up rules proves to be useful. If due attention is also paid to the various stirrer geometries then it is possible, with computer aid, to design an optimum agitator for a given purpose – this approach involves considerable effort but is necessary for proper design. A well‐conceived modular system and the influence of DIN standardization also preclude any uneconomical proliferation of agitator types without seriously limiting the flexibility demanded by the user.
Entwicklung des Trenndüsenverfahrens zur Uran‐Anreicherung
Authors: Becker Erwin Willy
Published: December 2004

Development of the nozzle separation process for enrichment of uranium. In the nozzle separation process an enrichment of 235U is achieved by extremely high centrifugal forces in a curved flow of UF6 diluted with a light gas. In Brazil a cascade section consisting of 24 nozzle separation stages has been constructed and has been in operation since late 1985. To produce nozzle separation systems with extremely small characteristic dimensions permitting plant operation at atmospheric pressure, a manufacturing process has been developed which relies on combined X‐ray lithography and microgalvanic deposition (LIGA‐technology). Using this technology the prototype separation stages constructed at the Karlsruhe Nuclear Research Center enable commercial nozzle separation plants with capacities of up to 3 Mio. SWU/year to be realized.
Expertensysteme — Aufbau und Anwendungsgebiete
Authors: Trum Peter , Iudica Norberto R.
Published: December 2004

Expert systems – structure and fields of application. Expert systems are programs for solving problems in narrow fields of application, which demand the competence of an expert. These systems, which process not only data but primarily knowledge, have attracted considerable interest in recent years. This contribution explains the principal characteristics and the mode of operation of expert systems, and dilineates their potential applications. Moreover, the approach adopted in the development of expert systems is briefly considered.
Brauchen wir Stoffaustausch‐Maschinen?
Authors: Mersmann Alfons , Voit Harald , Zeppenfeld Rolf
Published: December 2004

Do we need mass transfer machines? In contrast to mass transfer apparatus, the throughput of the phases as well as volumetric mass transfer rates in mass transfer machines are increased by moving machine parts (especially rotating and pulsating). This increase depends on the centrifugal acceleration expressed as the parameter z and the specific power input ε. This paper shows the dependence of the volumetric interfacial area, the gas‐side and liquid‐side mass transfer coefficients, and the volume ratio of machines and apparatus on the parameters z and ε. Furthermore, information is given about the increase of the specific power input ε of different mass transfer equipment with rising z.
Auskleiden und Beschichten von Apparaten mit Kunststoffen
Authors: Rimanek Rainer
Published: December 2004

Lining and coating of chemical apparatus with plastics. The object of this report is to provide a concise survey of applications for plastics in the lining and coating of steel constructions to avoid corrosion, erosion, and caking. Special attention is paid to the field of chemical apparatus and pipeline construction where, due to the requirements in question, the layer thicknesses amount to several millimetres.