bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Entwicklung der Destillationstechnik von ihren Anfängen bis zum Jahre 1800
Authors: Deibele Ludwig
Published: December 2004

Development of the technique of distillation from its beginnings up to the year 1800. Even today, distillation and rectification are still the most commonly used thermal separation methods employed for resolving mixtures of liquids into their individual components. Both techniques have a long history, and there is definite evidence for their use dating from the first century A. D. This development will be traced from its beginnings up to about 1800 and the major technological advances indicated. The overall time span is divided into five sections: antiquity up to 600 A. D; the Arabian epoch (800 to 1200); the Middle Ages (700 to 1400); late Middle Ages and Renaissance (1400 to 1600), Baroque and Enlightenment (1600 to 1800).
Endlagerung radioaktiver Abfälle
Authors: Neretnieks Ivars
Published: December 2004

Repositories for nuclear wastes. Repositories for nuclear waste are planned in many countries. The repositories will be located in deep geologic formations. In several countries crystalline bedrocks are studied for siting repositories. In Canada, Switzerland and Sweden there are large rock laboratories where various experiments are underway. In Sweden the first civilian repository for low and intermediate waste is in operation. The safety of a repository depends primarily on the hydrology, water chemistry, and the transport processes. The development of the chemistry and the transport processes are to a large part known from other areas of chemistry and chemical engineering. There are, however, differences which depend to a large part on the complex geometry of the flow paths. These differences call for new investigation and computing methods. Questions and problems relating to radionuclide transport from and safety of a repository for nuclear waste are described.
Betriebsleitsysteme zur Rezepturverwaltung und Produktionsdatenverarbeitung
Authors: Kersting Franz‐Josef
Published: December 2004

Plant control systems for administration of formulations and processing of production data. Hitherto, support from electronic data processing in a company was generally on the managerial level and benefitted the commercial/administrative tasks occurring there. On the other hand, automation of production has been accelerated by the increasing use of digital systems such as stored program systems, process controllers, electronic data acquisition devices, and laboratory automation and information management systems. However, there was a gap between the two which is now beginning to close since the introduction of plant control systems. The tasks of these systems lie in process‐proximate balance, quality assurance, production overviews, formulation procedures, and optimum plant control. The benefit of such plant management systems lies in the accessibility of up‐to‐date information to all qualified persons involved in plant management.
Mikrostrukturen aus Metall/Träger‐Wechselwirkungsprozessen an heterogenen Katalysatoren
Authors: Lamber Ryszard , Jaeger Nils , Schulz‐Ekloff Günter
Published: December 2004

Microstructures resulting from metal‐support interactions on heterogeneous catalysts. The term metalsupport interaction covers a large number of different phenomena due to forces of adhesion, charge transfer including the formation of chemical bonds, covering of the metal surface by reduced species from the support or the formation of new phases at the interfaces. The effect of such interactions on the efficiency and stability of catalysts is studied for numerous metal‐support systems. The formation of silicon‐metal alloys on silica, which has previously been considered as an inert carrier, as well as the formation of graphite on charcoal‐supported metal dispersions are described as examples of special interest. The new phases are characterized by methods of the analytical electron microscopy.
Schmelzkristallisation – theoretische Voraussetzungen und technische Grenzen
Authors: Wellinghoff Georg , Wintermantel Klaus
Published: December 2004

Melt crystallization – Theoretical presumptions and technical limitations. The fundamentals of the design of melt crystallization processes on cooled surfaces are presented. Determination of the energy requirement is the essential point. During each freezing step a multiple of the heat of solidification must be removed and must be re‐introduced during the subsequent melting step. Consequently, discontinuous processes of this nature can only compete with other thermal separation techniques – in which a continuous countercurrent operation can be realised – if the plant is well designed and the process is precisely controlled.
Abtrennung und Rückgewinnung von gasförmigen Stoffen durch Adsorption
Authors: Mersmann Alfons , Börger Götz‐Gerald , Scholl Stephan
Published: December 2004

Separation and recovery of gaseous substances by adsorption. After making a number of fundamental remarks on adsorbents, equilibrium, and kinetics of adsorption from the gas phase, the authors of this article first present a variety of regeneration methods. There follows a brief account of the methods used in the design of fixed bed adsorbers. The reader is then led via considerations of safety in the construction and operation of adsorbers to a number of practical examples from the areas of solvent recovery and flue gas purification.
Wäßrige Flüssigmembranen — Stand der Entwicklung
Authors: Ulbrich Michael , Marr Rolf
Published: December 2004

Aqueous liquid membranes – State of the art. Use of emulsion liquid membranes with an aqueous membrane phase is a promising technique for the separation of hydrocarbons, if distillation is difficult or impossible. Intensive investigations on aqueous membranes during the past five years have increased our knowledge of the mass transfer mechanism which exploits different solubilities and diffusivities for the separation of hydrocarbons. The influence of the most important process parameters on the selectivity of the separation and on an overall mass transfer coefficient, serving as a measure of the mass transfer rate, are discussed. Possible applications and further developments are presented.
Behandlung von Abwasser aus der metallverarbeitenden Industrie
Authors: Marquardt Kurt , Nagel Rolf
Published: December 2004

Treatment of waste water from the metal‐working industry. Recent legislation has triggered a round of innovation in purification techniques for the treatment of waste water from the metal‐working industry. The historical development took place essentially in three generations, viz. flow‐through processes, recycling ion‐exchange units, and process oriented work‐up. The process engineering of process oriented work‐up is basically known with regard to the unit operations. Work performed during the last two years has focussed on transforming the known processing principles into plant engineering and accomplishing the step to the industrial scale plant, i.e. to bring it up to the present state of the art.
Rechnergestützte Erstellung verfahrenstechnischer Prozeßmodelle
Authors: Marquardt Wolfgang
Published: December 2004

Computer‐aided generation of chemical engineering process models. The availability of adequate process models is still the most striking bottleneck for routine application of model‐based techniques in process design and operation. The development of knowledge‐based software tools to support process modeling is considered an important contribution to a solution of this problem. After a brief summary of the modeling tools offered in current simulator architectures, a future knowledge‐based modeling tool is sketched. In addition to the software engineering, the acquisition and formalization of the modeling knowledge – comprising meaningful submodels and generic modeling strategies – is essential for the feasibility of the approach and for the acceptance of a tool. Therefore, these two themes are discussed in considerable detail. Finally, first prototype developments towards a knowledge‐based modeling tool are presented.
Optische Konzentrations‐ und Temperatur‐Messung in Aerosolen und Sprays
Authors: Schweiger Gustav
Published: December 2004

Optical measurement of concentration and temperature in aerosols and sprays. This article surveyes progress in the development and application of optical methods, particullarly in Raman scattering and fluorescence for the analysis of aerosols and sprays. The main emphasis lies on examination of the particle phase. Fundamentals and state of the art in the determination of molecular composition of the particle phase with the aid of linear and simulated Raman scattering are described and the role of structural resonance discussed. Various models are presented for distinguishing between the contribution of the liquid and the gas phase to Raman scattering and fluorescence. Finally, new developments pertaining to the measurement of droplet temperature in aerosols and sprays are described.
Einsatz von Biowäschern in der chemischen Produktion
Authors: Stockhammer Stefan , Schäfer‐Treffenfeldt Wiltrud , Zetzmann Klaus
Published: December 2004

Use of bioscrubbers in the chemical industry. Bioscrubbers are an ecologically and economically interesting alternative to conventional processes like combustion, adsorption and absorption. A brief account of the microbiological and engineering fundamentals of bioscrubbers are given followed by a review of new developments illustrating improvements in process design. The field of application for bioscrubbers is continuously expanding. Two examples of the use of bioscrubbers are discussed. They demonstrate the feasibility of deodorization of slightly contaminated waste gas, as well as the purification of waste gas which is highly loaded with organic substances. The authors describe a new concept for reduction of local hold up of biosuspension at the bioscrubber by integrating the waste water plant as a superior reservoir for fresh biosuspension. The most important advantages of the new concept are as follows: No problems with shut‐off time, a better safety in operation, and ready adaptation of the process to changing parameters.
Stand der Emissionsmeßtechnik im Abgas der Rückstandsverbrennung
Authors: Jockel Wolfgang
Published: December 2004

State of the art of emission measuring techniques in the flue gas of waste incineration plants. It is necessary to critically consider measuring techniques in the light of new requirements for waste incinerators (17th ordinance dating from Dec. 1990). Selected examples are concerned with the primary components of flue gas: particulate matter and trace metals, organics with total carbon content, and important groups such as organochlorine compounds (e.g. dioxins/furans) and inorganic chlorides (such as hydrogen chlorine). The evaluation concludes by considering manual techniques as well as monitoring systems and measures for quality assurance. Finally, an account of recent developments in the monitoring of ammonia and mercury is presented.
Biologisch abbaubare Kunststoffe: Testverfahren und Beurteilungskriterien
Authors: Augusta Josef , Müller Rolf‐Joachim , Widdecke Hartmut
Published: December 2004

Biodegradable Polymers: Test Methods and Assessment Standards. Technological difficulties in plastics recycling as well as critical emission into the environment during waste incineration give rise to considerations of utilizing plastics in composting systems. While market supply of ‘biodegradable plastics’ is increasing there is a need for test methods and assessment standards for these substances. This paper presents the basis and discusses microbial procedures, analytical techniques and requirements for the tests to be developed.
Einsatzmöglichkeiten hydrophober Zeolithe in der Adsorptionstechnik
Authors: Otten Wilhelm , Gail Ernst , Frey Thomas
Published: December 2004

Der Einsatz von Zeolithen in der adsorptiven Abluftreinigung und Lösungsmittel‐Rückgewinnung scheiterte bisher daran, daß handelsübliche Zeolithe bevorzugt Wasserdampf adsorbieren. Durch spezielle Synthesen oder Dealuminierungsverfahren können Zeolithe hergestellt werden, die extrem hydrophob, hoch temperaturbeständig und säurestabil sind. Diese Zeolithe sind daher geeignet, selektiv organische Lösungsmittel aus feuchten Abluftströmen zu adsorbieren. Die Unbrennbarkeit der Zeolithe verhindert die Selbstentzündung des Adsorbens. Höhere Desorptionstemperaturen ermöglichen geringere spezifische Energieverbräuche sowie die Ad‐ und Desorption von Schwersiedern und polymerisierenden Produkten. Die geringe Wasseraufnahme reduziert den Energiebedarf bei hohen Abluftfeuchten und erlaubt die Rückgewinnung wasserarmen Lösungsmittels. Mit geeigneten Bindemitteln lassen sich die Zeolithe zu Hohlzylindern mit geringem Druckverlust verformen oder zur Beschichtung von Wabenkörper‐Rotoren einsetzen.
Strukturwandel in der Ingenieurtechnik der chemischen Industrie
Authors: Lipphardt Günter , Pilz Volker , Plöcker Ulf , Wintermantel Klaus
Published: December 2004

Changes in the Structure of Engineering in the Chemical Industry. The poor profit situation has stimulated a discussion of the costs of engineering in the chemical industry. The allocation of engineering responsibilities to centralized organizational structures is at issue. This applies to planning just as much as to plant maintenance or to the workshops. These structures are regarded as inflexible, expensive and, in many cases, monopolistic. Decentralized units which are directly responsible to divisions or business units seem to be able to work more efficiently and cheaply. The best alternative, however, is considered to be the outsourcing of work to external firms on a far larger scale than up to now. The article deals with the reasons which have initiated the structural change and with the relating consequences thereto.
Klärschlammpyrolyse mit Rückstandsvergasung
Authors: Schuller Dieter , Brat Boris
Published: December 2004

Pyrolysis of Sewage Sludge Combined with Gasification of Char. Dried sewage sludge was pyrolyzed over a temperature range of 550 to 650°C and the char produced during this reaction was gasified with steam in a succeeding step at 900°C. Both reactions were carried out in a fluidized‐bed reactor. Besides the composition of products, vaporization of heavy metals and the suitability of the gasification ash for landfilling were investigated. The results indicate that the combined process of pyrolysis and gasification of char can be looked upon as a promising method of disposing of sewage sludge.
Anwendung von Polyelektrolyten bei der mechanischen Fest/Flüssig‐Trennung
Authors: Kulicke Werner‐Michael , Lenk Sylvia , Detzner Heinz‐Dieter , Weiß Thomas
Published: December 2004

Use of Polyelectrolytes in Mechanical Solids/Liquid Separation. This article shows how optimisation tasks for the dewatering of sludge can be solved by starting from studies of chemical structure and steric properties of polyelectrolytes and laboratory experiments based thereon with a trans‐portable computer‐aided flocculation and dewatering apparatus. The optimum polyelectrolyte dosage lies in the range of the critical concentration c* (viscosimetric measurements) of the dissolved polyelectrolytes. On optimisation of the flocculant regime for mechanical solids/liquid separation by combined addition of anionic and cationic polyelectrolytes (dual process), it is necessary to consider the overall system of sedimentation and filtration. In an industrial scale plant, the consumption of flocculant could be reduced by up to 10% compared to laboratory studies. At the same time, the dewatering behaviour could be improved by up to 60%, a shearing strength of the sludge in excess of 20 kN/m2 reliably established, and plant operating reliability achieved for changing sedimentation properties.
Qualitätssicherung im Anlagenbau
Authors: Eisenächer Karl , Meurer Peter , Stork Werinhard
Published: December 2004

Quality Assurance in Plant Design and Construction. In the field of chemical plant design and construction, quality is understood to mean the strict application of the state‐of‐the‐art rules and the fulfilment of all specific requirements specified by the client, including plant take‐over by the client in accordance with the time schedule. Chemical plants can rarely be handled in the same manner as series products. Therefore, quality assurance requires a large organizational scheme. The definition of quality and the system applied to ensure an adequate quality standard are a rather complicated task. The technical divisions involved in a project are responsible for the quality, i.e. there is no sharing of responsibility. It is also impossible to shift this responsibility to a special QA department.
Expertensysteme in der Verfahrenstechnik — Konfiguration von Rührapparaten
Authors: Knoch Achim , Bottlinger Michael
Published: December 2004

Expert Systems in Chemical Engineering – Examples in the Configuration of Agitators. The structuring of relevant knowledge and its formalized representation in a knowledge base is the main prerequisite in employing an expert system. The present paper discusses functionality and conception of expert systems and explains their advantages over conventional programming. Furthermore, the structure of an expert system for the configuration of agitators in food processing is presented.
Auswahl von Sorbenzien für die Gasphasenadsorption
Authors: Eiden Ulrich , Ciprian Jürgen
Published: December 2004

Selection of Sorbents for Gas Phase Adsorption. For gas phase adsorption processes it is almost always necessary to select a suitable sorbent by experiment, i.e. a sorbent that is suitable for adsorption as well as for desorption. Therefore sorbents from the group of activated carbons, adsorbent resins and zeolites have been tested and compared with each other under adsorption and desorption conditions. The sorbents have also been checked for reliable function. Operational disturbances are often caused by components such as water vapor or (irreversibly adsorbing) high boiling components. In any case it is useful to select adsorbents which are not susceptible to interference by these components. The co‐adsorption of water vapor, undesirable in practice, normally leads to a reduced adsorbent capacity. It is also shown that a single high boiling component, present in traces in the gas, loads the adsorbent to the same extent as the pure main component, so that there is hardly any capacity left for the main component. The range of investigation was insufficient to draw up general rules for the different groups of sorbents referring to the points considered.
In‐situ‐ und On‐line‐Überwachung und Regelung biotechnologischer Prozesse
Authors: Schügerl Karl , Bellgardt Karl‐Heinz , Kretzmer Gerlinde , Hitzmann Bernd , Scheper Thomas
Published: December 2004

In‐Situ and On‐Line Monitoring and Control of Biotechnological Processes. The advantages of in situ and on‐line monitoring of biological production processes are demonstrated by four examples: production of baker's yeast, manufacturing of alkaline protease by B. licheniformis, formation of intracellular fusion protein by recombinant E. coli, and production of antibiotica by ascomycetes and streptomycetes.
Statistische Prozeßführung (SPC) und Automatisierung (APC)
Authors: Staal Rolf , Rathert Hermann , Schloßer Gerhard
Published: December 2004

Statistical Process Control (SPC) and Automatic Process Control (APC). Statistial Process Control as developed by Shewhart and Deming is being used internationally as a method for continuous improvement and cost reduction. SPC is applied to manufacturing and service industries, and is now being used more and more in Germany. In the chemical industry many processes are equipped with automatic control or advanced control strategies. This article outlines how SPC and APC supplement each other. The first part describes APC methods as a means of achieving constant quality. The second part describes SPC in its original form as a method for continuous quality improvement. After the comparison of SPC and APC an example is presented: automatic rectifying column. The combined application of SPC and APC leds to synergistic results which would have been hard to achieve otherwise.
Simulationsmodelle zur Berechnung der Explosionsgrenzen brennfähiger Gasgemische
Authors: Rennhack Rolf , Thiel‐Böhm Andreas
Published: December 2004

Simulation Models for Calculating Explosion Limits of Combustible Gas Mixtures. A survey of current knowledge of explosion limit simulation for combustible gas mixtures is given. These models are important for estimating safety risks during process development and plant engineering. Therefore theoretically based and empirical equations are applied. The main subject of this paper deals with the simulation of explosion limits of multicomponent combustible gas/inert gas/oxidant mixtures depending on gas composition and temperature. New developments providing an important basis for software development are presented. Missing determinations and application limits are discussed.
Simulation von Kristallisations‐ und Fällprozessen
Authors: Pawlowski Juri
Published: December 2004

Simulation of Crystallisation and Precipitation Processes. The various processes of crystallisation and precipitation lead to a wide variety of particle size distributions, which are also subject to the influence of the specific properties of the material systems. It was examined whether and to what extent these processes can be described in process engineering terms by a consistent simulation with a unified basic model of crystallisation. The basic model corresponds essentially to known concepts: it is based on the law of mass action but purposely omits ad hoc proposals found in the literature in the formulation of nucleation/nucleus decline kinetics. The results of simulation obtained for various material systems and processes demonstrate considerable adaptability of the basic model. It appears to be suitable for uniform description and to serve as an adequate basis of development of crystallisation‐specific properties of material systems.
Rotoradsorber zur Abluftreinigung und Lösungsmittel‐Rückgewinnung
Authors: Konrad Gerhard , Eigenberger Gerhart
Published: December 2004

Rotary Adsorbers for Waste Air Purification and Solvent Recovery. Thanks to their compact construction and low pressure drops, adsorbers with rotating adsorbent beds are highly suitable both for retrofitting of waste air purification units and generally for the removal of absorbable components from gas streams. When used in conjunction with straightforward hot gas desorption they permit almost complete purification of gas flows with concomitant concentration of the separated components in the desorbate by a factor of 10 to 20. They can also be used in conjunction with recovery of the separated components by partial condensation of the desorbate. Owing to the fixed coupling of adsorption and desorption times, which is determined by the geometry of the unit, the behaviour of the system is distinctly different from that of conventional multiple bed systems in cyclic operation. A detailed model description and computer simulation of operating behaviour are particularly useful for their analysis. It is shown that the behaviour of commercially available rotor concepts can be much better understood in this way and new concepts for exhaust air purification with integrated solvent recovery can be developed which are characterised by significantly reduced energy requirements for desorption and condensation.
Die großtechnische Oxosynthese mit immobilisiertem Katalysator
Authors: Wiebus Ernst , Cornils Boy
Published: December 2004

Industrial Oxo Synthesis with Immobilised Catalyst. The use of water‐soluble catalysts represents a significant advance in homogeneous catalysis; “immobilisation” of the catalyst in a second immiscible liquid phase has the effect of “heterogenisation” and allows the advantages of heterogeneous processing (long lifetimes, straightforward technology) to the combined with those of the homogeneous mode (gentle reaction conditions, high activity and selectivity). In particular, the decisive advantage of homogeneous catalysts, viz. the wide range of variation of their steric and electronic properties which can be adapted to the specific reaction at hand, can be exploited for tailoring highly effective catalysts. Moreover, the mode of action of these homogeneous catalysts remains understandable as a model and under the reaction conditions chosen – in complete contrast to the case of many heterogeneous catalytic systems. The first successful industrial application of water‐soluble catalysts was in the oxo process of Ruhrchemie/Rhǒne Poulenc. The following article reports on ten years' experience with this process and the HRh(CO)[P(msulphophenyl‐Na)3]3 catalyst.
Der Begriff der hochwertigen Dichtung für lösbare Rohrleitungsverbindungen
Authors: Simon Eberhard
Published: December 2004

Concept of High‐Quality Seals in Disconnectable Pipeline Connections. The “Technical Instruction Air” of the Federal Republic of Germany stipulates the use of highquality gaskets in flange connections employed in handling of certain hazardous materials, but it gives no detailed informations concerning the high‐quality criterion. This article gives reasons why the highquality criterion should be extended on all elements of disconnectable pipeline connections of various types which are to be evaluated as systems. It further discusses the basic aspect of quality management as well as the terms „secluded emission”︁ and “diffuse emission”, which should be avoided or minimized respectively. The following criteria of high‐quality pipeline connections are discussed: Design reserves, corrosion resistance, position fixing, safety against fracture without deformation, tightnessperiod and process hygiene.
Scale‐up von Destillationskolonnen
Authors: Eiden Ulrich , Kaiser Rudolf , Schuch Gunter , Wolf Dieter
Published: December 2004

Scale‐up of Distillation Columns. In spite of remarkable advances in the development of computer programs for calculations on distillation columns, it is frequently still impossible to design them without experimental testing. Economic constraints demand use of miniaturised test plant, thus enhancing the importance of laboratory measurements. A system is presented for scale‐up of separation which required information from laboratory experiments, includes data from reference columns, and takes account of models of fluid dynamics and mass transfer. The special feature of this approach lies in the free choise of internals, both in the laboratory and in the designed column.
Dynamische Simulation von Wärmeübertragern
Authors: Botsch Tilman Walter , Stephan Karl
Published: December 2004

Simulation of the Dynamic Behaviour of Heat Exchangers. Four models for heat exchangers under transient conditions are presented. Three of them describe a single phase heat exchanger, and the forth one is used for the simulation of a condenser. All models are of intermediate complexity and valid for simulation of both single heat exchangers and chemical processes. They use distributed variables and incorporate the calculation of local heat transfer coefficients so that temperature profiles over the apparatus can be determined in addition to the transient behaviour of the outlet variables.
Neue Thermoplastische Elastomere: Rezeptierung, Aufbereitung und Werkstoffeigenschaften
Authors: Fritz Hans‐Gerhard
Published: December 2004

New Thermoplastic Elastomers: Formulation; Compounding; and Material Properties. This article described novel thermoplastic elastomers (TPO) consisting of a PP matrix and a synthetic rubber phase crosslinked in a new way with organosilanes. The mechanical and rheological properties of the blend are determined primarily by the phase structures produced in the course of compounding. PE‐ULD can also be used as synthetic rubber in place of EP(D)M, with the attendant advantage of reduced swelling in oils.
Eine gefragte Unternehmer‐Tugend: Kommunikations‐Fähigkeit
Authors: Röglin Hans‐Christian
Published: December 2004

Our modern industrial society produces not only goods but also distrust. Its confidence crisis is an expression of unsolved communication problems. The high degree of abstraction of modern technology and organisation makes the world incomprehensible. A fundamental change of attitudes removes traditional and familiar order without providing new orientation. A surfeit of information, due in part of television, leads to further disorientation. The basic mood of such an insecure society is a diffuse „angst”︁. This presents one of the great challenges of communication. A communication which can meet this challenge requires sincerity on the part of the persons involved, must be of the nature of a dialogue, i.e. open, and must be comprehensive, i.e. must address and express negative aspects. Only then can the kind of credibility arise which permits successful communication.
Validierung in der Prozeßleittechnik
Authors: Hensel Hartmut
Published: December 2004

Process control systems are being increasingly introduced in pharmaceutical production plant. They exercise quality‐relevant functions and are thus subject to legal requirements of validation. It must therefore be established and documented that a process control system fulfills specific requirements. The technical part of this task lies in qualification of the process control system. The present article described the basic principles of such process control system qualification, services for setting up a process control system with obligatory validation, qualification‐oriented control system functions, and support of the control system manufacturer in validation.
Formselektives Reformieren an zeolithhaltigen Reformierkatalysatoren
Authors: Meusinger Josefin , Neubauer Torsten , Reschetilowski Wladimir
Published: December 2004

Use of bifunctional Pt/Al2O3 catalysts in catalytic reforming units significantly improved production. During the past four decades the power of such catalyst systems has been continuously increased by the introduction of various catalyst modifications. Use of reforming catalysts containing zeolites permits combination of shape selectivity with the conventional reforming reaction. Here, the suitability of an erionite containing catalyst for the reforming processes is demonstrated. Gasolines produced with zeolite catalysts are characterised by high values of octane numbers and low content of carinogenic benzene.
Gleichzeitige Erfassung von Partikelmerkmalen und Eigenschaften mehrphasiger Strömungen mit Hilfe der Phasen‐Doppler‐Anemometrie
Authors: Bauckhage Klaus
Published: December 2004

While conventional phase‐Doppler anemometry (PDA) is already widely used for nonintrusive and simultaneous particle sizing and particle velocity measurements as well as for particle flux measurements in two phase and multiphase flows, there is a lack of knowledge surrounding the additional potential of PDA for particle material recognition and for concentration as well as temperature measurements on the base of rainbow angle displacements, for particle shape diagnosis and – if PDA extensions are used – for submicron sizing. This potential makes PDA most attractive to chemical enginering, i. e. to industrial processing and to research and development. Evaluation of recent PDA literature trends and procedures for setup optimisation as well as for raw data processing will be discussed.
Massen‐ und ortsfeste Betrachtungsweisen bei der Reaktormodellierung
Authors: Platzer Bernd
Published: December 2004

Due to the development of computers one may have the impression that the differences between methods of fluid mechanics and of chemical reaction engineering are diminished. But important differences survive, and their disregard can lead to misunderstandings. The main difference is the domination of the mass related view in reaction engineering and of the position related view in hydrodynamics. The analysis of the fundamentals result in the incorporation of the reaction kinetics and of the residence time distribution. Taking this into account, the dispersion model and the convection diffusion model are compared and the character of the axial dispersion coefficient and of the boundary conditions are discussed. It can be seen, that a direct transformation of hydrodynamics results is not possible. The simulation of the life history of molecules and particles offer an alternative for this.
Hydrodynamische Beanspruchung von Rührorganen
Authors: Pahl Manfred H. , Knoch Achim
Published: December 2004

Mechanical design of agitation equipment requires information about the hydrodynamic stresses acting on impeller shafts, baffles, and vessels. In particular, vibrations induced in the generally freely supported impeller shafts impose very strong stresses on the shaft bearings at the natural frequency of the assembly and can lead to shaft fracture in extreme cases. Depending upon the speed of rotation, the surrounding medium acts as variable damping member owing to the differing flow conditions. This situation is examined in the present article.
Zur Verfestigung von Schüttgütern – Mikroprozesse und Kinetikmodelle
Authors: Tomas Jürgen
Published: December 2004

Storage tanks are important elements of a self‐operating closed processing system. The reliability and availability of storage equipment essentially depends on the flow behaviour of particulate solids in storage containers. A wide residence time distribution (i.e. too long a storage time at rest) in silos, bunkers or transportation containers, respectively, can lead to the hazardous problem of so‐called “time consolidation” of particulate solids. During this hardening process, solid bridges are forming with resulting solidification and solid properties of bulk material. In principle, there are four main physico‐chemical effects in bulk materials storing and handling which can produce solid briding between the particle contacts due to crystallisation, chemical reactions, solidification of high‐viscous bonding agents and sintering. Generally, new adhesion force based models are presented to describe the consolidation kinetics of particulate solids. Preliminary solutions of kinetic model equations are discussed and compared with new test results and practical conclusions are drawn concerning the reliable processing, storage and transportation of bulk materials.
Zerkleinerung von Abfällen mittels Rotorscheren, Rotorreißern und Schraubenreißern
Authors: Jäckel Hans‐Georg , Schubert Gert
Published: December 2004

Starting from the properties of the materials constituting waste, approaches suitable for size reduction of tough materials are considered. The rotary shears, rotary shredders, and screw shredders that have recently come into use for preliminary, coarse, and medium‐level size reduction of bulky household waste, scrap wood, used tyres, biological waste, old documents are now widespread. The forces exerted by these machines and their design and important design parameters are examined. A necessary detailed comparison of the three basic types of machine depending upon the nature of the material handled (systematic size‐reduction studies) has yet to be performed.
Verfahrenstechnik im Wandel
Authors: Frey Walter , Lohe B.
Published: December 2004

In the era of globalization, the speed of change is closely related to both the population growth in developing countries and their desire to close the economic gap with the western hemisphere. Chemical engineering is considered a significant contributor in finding solutions to the subsequent challenges of food supply, energy demand and environmental impact. National economies and their constituent enterprises require qualified engineers to meet these urgent and economically demanding challenges. At present however, neither the number of engineering students nor the national focus of university education seem appropriate to cover future requirements. On the scientific level, new modelling techniques, CFD and novel system orientied methods provide a perpective for both product and process improvements. In addition to their technical ability, professional engineers must emply a flexible approach as well as soft skills to put innovative solutions into practice. This paper illustrates and details the contents of the „Memorandum Verfahrenstechnik”︁ [3], a list of recommendations which was prepared by representatives of both industry and university.
Füllkörper oder Packungen? Wem gehört die Zukunft?
Authors: Schultes Michael
Published: December 2004

Over the years a large number of dumped and ordered packings have been developed for effective treatment of material in absorption, desorption, extraction and rectification columns. The task of these column packings is to improve the mass transfer between a liquid phase and a gas or vapor phase. Furthermore, they also have to assure large throughputs at low pressure drops. When elaborating possible solutions for the separation of liquid mixtures or for cleaning flows of waste air or waste water in mass transfer columns, the planning engineer repeatedly faces the question of which dumped packing or which arranged packing presents the most favorable design from a process engineering standpoint. In recent years the opinion has often been voiced that arranged packings are always more effective than dumped packings. The purpose of this paper is to show that a number of applications exist in which modern dumped packings are equal or even superior to arranged packings. On the basis of selected examples the author discusses when the use of a structured packing is preferable with regard to process engineering.
Modellbildung für die zweiphasige Strömung in geordneten Schichtungen und strukturierten Packungen
Authors: Millies Marco , Mewes Dieter
Published: December 2004

Modelling of Binary Flow in Ordered Layers and Structured Packings Ordered layers and structured packings are used as internals in numerous rectification columns. They characteristically exhibit low pressure drops and high plate numbers per unit length. The relatively high investment costs are frequently offset by small column dimensions and hence lower equipment costs. In packings of industrial dimensions unstable flow states may occur which significantly lower the plate numbers. Such instabilities can be detected experimentally by tomographic methods. Moreover, flow patterns can be predicted theoretically. A theoretical description permits the engineer to scale up such columns containing packings and to deduce the design features necessary for industrial scale columns from laboratory experiments.
Praxisrelevante Zetapotentialmessung mit unterschiedlichen Meßtechniken
Authors: Hinze Frank , Ripperger Siegfried , Stintz Michael
Published: December 2004

Practice‐Related Zeta Potential Measurement Using Different Measurement Techniques.

The importance of particle systems with particles sizes in the submicron range is steadily growing. Therefore the need for a comprehensive characterisation of these material systems is also increasing. In addition to the particle size, in dispersions the formation of a surface potential and the ensuing inclination of the particle to agglomerate is of particular interest. The zeta potential has long been used as a measurement value. The complexity of this value and the sensitive reaction of the sorption equilibria which cause the potential formation require great care in performing the measurements. In this paper the comparability of measured results gained by different measurement methods will be discussed. This will be done exemplarily with influencing factors such as sample preparation, standing time of the sample, electrolyte background, titration regime, solid concentration and measurement technique. In conclusion, some advice is given for the selection of suitable measurement parameters.
DVCV‐Gemeinschaftsausschuß „Extraktion”︁
Authors: Bart Hans‐Jörg , Schröter J.
Published: December 2004

Die 7. Sitzung des DVCV‐Fachausschusses Extraktion fand vom 17. bis 18. September 1998 in der „Rotunde”︁ des Gebäudes 57 der Universität Kaiserslautern statt. Dort fanden die insgesamt ca. 70 Teilnehmer beste Bedingungen vor, um die elf Vorträge der beiden Schwerpunktthemen „Simulation (einschl. Short‐cut‐Methoden) und Miniplant‐Versuche zur Bewertung der Flüssig/Flüssig‐ und der Reaktivextraktion”︁ und „Koaleszenz und Phasentrennung”︁ sowie weitere fünf Fachvorträge zu diskutieren. Außerdem erfolgten zwei Computerdemonstrationen, erstens zur Datenbank „Extraktionskolonnen”︁ und zweitens zur „Auswahl selektiver Extraktionsmittel für die Metallsalzextraktion auf der Basis von Calixarenen”︁. Die Sitzung wurde von Prof. Dr. W. NITSCH, TU München, und Herrn J. SCHRÖTER, BAYER AG, eröffnet und geleitet.
International Workshop on Polymer Reaction Engineering
Authors: Moritz H.‐U.
Published: December 2004

Der in der Zeit vom 5. bis 7. Oktober 1998 zum sechsten Mal in Berlin durchgeführte „International Workshop on Polymer Reaction Engineering”︁ der DECHEMA hat sich längst als das herausragende Forum für Diskussionen und den Ideenaustausch im Bereich der Polymerisationstechnik etabliert. Mit über 150 Teilnehmern aus 18 Ländern, die zu mehr als 50% aus der Industrie kamen, stellt der Workshop einen intensiven, internationalen Erfahrungsaustausch zwischen Industrie und Hochschule sicher. Einen thematischen Schwerpunkt bildete die Emulsionspolymerisation, wo im Vergleich mit den vorangegangenen Tagungen eine kontinuierliche Steigerung der Beiträge zu verzeichnen war. Zu der erstmals als eigenständiger Themenkreis vertretenen Olefinpolymerisation wurde auf Anhieb in zahlreichen Beitragen berichtet. Ein zunehmendes Interesse zeichnet sich ebenso für die Reaktivextrusion ab.
Fluiddynamische Aspekte in Mikrostrukturreaktoren
Authors: Walter Stefanie , Frischmann Günter , Broucek Reinhard , Bergfeld Manfred , Liauw Marcel
Published: December 2004

Fluid Dynamics in Microchannel Reactors.

The possible benefits of using microchannel reactors in the chemical process industries have been under discussion for several years. Outstanding heat transfer properties, short residence times and short diffusion lengths are considered key advantages, while the cost of the approach and the pending question of long‐term stability are still major sources of skepticism. A good starting point for a feasibility study is to investigate some major fluid dynamic properties. For a unit consisting of hundreds of parallel microchannels, the pressure drop for the laminar flow is just a few millibar. However, at high gas flows the distribution over the numerous channels may become non‐uniform. It is shown how the resulting residence time distribution affects both the yield of intermediates in consecutive reactions, and step functions of the concentration during periodic operation, respectively. All in all, the results of the estimations are encouraging.
Wärmeintegration als Element der Verfahrensbearbeitung
Authors: Aust Eberhard , Scholl Stephan
Published: December 2004

Thermal Integration, an Element in Design of Chemical Engineering Processes.

Thermal integration is an important element in the planning and design of chemical engineering processes. This is especially true when energy optimisation is embedded in a software environment permitting unimpeded data transfer and exchange between the design elements can take place in a straightforward and intelligent manner, i.e. in a manner supporting the user. These advantages are demonstrated for a selected process. Expert systems which can extract data relevant for thermal integration from the process data and hence generate an entry data set for subsequent processing in a thermal integration program have proved to be particularly advantageous. In addition, the process engineer also has the possibility of modifying the data manually and undertaking appropriate adaptions and corrections. Subsequent analysis of thermal integration (e.g. by the Pinch method) often suggests improvements extending beyond the pure thermal regime and lead to changes in the process flow chart.
Produktivitätssteigerung durch integrierte Produktionstechnik und Verfahrens‐Know‐how
Authors: Roos Eckhard , Wippermann Boris
Published: December 2004

Increasing Productivity through Integrated Production Engineering and Processing Expertise The future of production engineering is interdisciplinary. Between product innovation and product marketing there lies a design process which has to be optimised and which is interdisciplinary in character. The design process has to satisfy the demands of global markets on chemical products, which lead, for example, to shorter and shorter product life cycles, and to demands for low production costs, high and consistent product quality, and faster market launches.
Grundlagenuntersuchungen zur Herstellung von Öl/Wasser‐Emulsionen im Ultraschallfeld
Authors: Bechtel Siegfried , Gilbert Norbert , Wagner Hans‐Günter
Published: December 2004

Basic Research on Ultrasonic Production of Oil‐in‐Water‐Emulsions This article presents basic research results for production of oil in water emulsions under ultrasonic irradiation. A new theoretical model supports experimental work. Special attention is given to the transfer of batch experiments to continuous emulsification processes. Our experimental findings prove that final drop size essentially depends on specific power density. Drop size decreases with increasing residence time in the ultrasonic field until a system specific, minimum drop size is obtained. Ultrasonic irradiation leads to turbulent flow conditions on a macroscopic and a microscopic scale. Our model based on the theory of turbulent drop break up predicts drop size and can be used to design equipment for ultrasonic emulsification.
Dexamethasone alters F‐actin architecture and promotes cross‐linked actin network formation in human trabecular meshwork tissue
Authors: Clark Abbot F. , Brotchie Daniel , Read A. Thomas , Hellberg Peggy , English‐Wright Sherry , Pang Iok‐Hou , Ethier C. Ross , Grierson Ian
Published: December 2004

Elevated intraocular pressure is an important risk factor for the development of glaucoma, a leading cause of irreversible blindness. This ocular hypertension is due to increased hydrodynamic resistance to the drainage of aqueous humor through specialized outflow tissues, including the trabecular meshwork (TM) and the endothelial lining of Schlemm's canal. We know that glucocorticoid therapy can cause increased outflow resistance and glaucoma in susceptible individuals, that the cytoskeleton helps regulate aqueous outflow resistance, and that glucocorticoid treatment alters the actin cytoskeleton of cultured TM cells. Our purpose was to characterize the actin cytoskeleton of cells in outflow pathway tissues in situ, to characterize changes in the cytoskeleton due to dexamethasone treatment in situ, and to compare these with changes observed in cell culture. Human ocular anterior segments were perfused with or without 10−7 M dexamethasone, and F‐actin architecture was investigated by confocal laser scanning microscopy. We found that outflow pathway cells contained stress fibers, peripheral actin staining, and occasional actin “tangles.” Dexamethasone treatment caused elevated IOP in several eyes and increased overall actin staining, with more actin tangles and the formation of cross‐linked actin networks (CLANs). The actin architecture in TM tissues was remarkably similar to that seen in cultured TM cells. Although CLANs have been reported previously in cultured cells, this is the first report of CLANs in tissue. These cytoskeletal changes may be associated with increased aqueous humor outflow resistance after ocular glucocorticoid treatment. Cell Motil. Cytoskeleton 60:83–95, 2005. © 2004 Wiley‐Liss, Inc.