bluuebunny/crossref_metadata_2025 huggingface dataset:
Neue Aspekte zum Einfluß des Blasenwakes auf die Hydrodynamik und den Stoffaustausch in einer Blasensäule
Authors: Wasowski Tomasz , Blaß Eckhart
Published: December 2004

New aspects of the influence of the wake of bubbles on fluid dynamics and mass transfer in bubble columns.Wake‐phenomena behind solid and fluid particles moving in a continuous liquid are an important fluid‐dynamic effect which has a pronounced influence on heat‐ and mass transfer in two‐phase dispersions. In this paper results reported in the literature are used to analyse the influence of wakes behind bubbles on the hydrodynamics of bubble columns. A new class of model is introduced to describe the flow and mixing of the liquid phase, taking into account major hydrodynamic effects.
Werkstoffauswahl für luftgekühlte Wärmeaustauscher
Authors: Paikert Paul
Published: December 2004

Choice of materials for air‐cooled heat exchangers. Air has many advantages as a coolant for industrial processes. It is available in any desired quantity and does not incur costs for supply and disposal. Although air is far less corrosive than water, there are limitations for certain materials and air contaminations. The possibility of using different materials for the process side and the cooling air side, with the latter preferably having an enlarged surface area, can be exploited to advantage to take account of material‐specific properties of the two sides. Process‐dictated limits of optimum surface area increase and temperature‐dictated limits of application and proven fin patterns, are demonstrated. Attention is drawn to actual cases of damage taken from practice and their lessons and also to some unexplained cases.
Prinzipien der Herstellung und Stabilität von Emulsionen
Authors: Schubert Helmar , Armbruster Harald
Published: December 2004

Principles of formation and stability of emulsions.The present state of knowledge concerning the principles of emulsion formation and stability are summarised and new theoretical and experimental results are presented. Also described are the characteristic features of the most common types of machines used for emulsification and the mechanics of droplet disruption in laminar and turbulent flow as well as cavitation. In laminar flow, the minimum droplet size is theoretically determined by the shear stress and regulated by a critical Weber number, provided that the particular emulsifier can rapidly occupy sites on the newly formed interface. If this occupation is inhibited, than only larger droplets can be formed. The upper size limit can be calculated from kinetic considerations. The second part of the paper addresses the fundamentals of emulsion stability and the emulsifier's influence on interactions between dispersed droplets. A way of describing the state of the droplets in an emulsion at rest using a population balance theory is also discussed.
Biosensoren –‐ Sensoren für die Biotechnik?
Authors: Kasche Volker , Renken Eckhard
Published: December 2004

Biosensors – Sensors for biotechnology? Increasing analytical requirements are to be expected in biotechnology, diagnostics, and environmental protection as a result of increasing product purity demands and the need to satisfy legal requirements. Biosensors are suitable for some of these purposes. The present review discusses the principal types and properties of such sensors in order to compare them with other sensors for the same purpose. It is seen that biosensors in combination with equipment having automated sample preparation and calibration can serve to overcome shortfalls in managing the increased analytical requirements for a number of substances.
Photovoltaik‐Anlagen
Authors: Stahl Dietrich
Published: December 2004

Photovoltaic plant. Presently available technologies for production of photovoltaic cells and modules and the principal developments aiming to improve the price/performance structure of the components are described in this article. Considerable attention is devoted to differences between the crystalline silicon cell (thick‐layer technology) and the thin‐layer cell. A description follows of the structure of simple to sophisticated photovoltaic systems of 100 Wp to 20 kWp, as well as the developmental status of the principal system components such as alternating and direct current converters. In the second part, the costs of photovoltaic plant are discussed from a present‐day viewpoint and the costs made comparable with those of conventional generation plant. The special significance of operating cost comparisons instead of those of pure investment costs in the examination of economic applications of photovoltaic systems is emphasized.
Trockenentschwefelung für Kombikraftwerke mit Kohlevergasung
Authors: Hederer Hartmut
Published: December 2004

Dry desulphuration of combination power stations with coal gasification. Dry gas purification processes for combination power stations can raise the thermal efficiency by 1 to 4%. This increase in efficiency is due, on the one hand, to the higher heat content of the gases, and on the other hand to avoidance of loss of combustible components during wet scrubbing, the constant water vapour content, and the possibility of using low‐pressure steam, e.g. for drying the coal prior to gasification. The various possibilities of dry desulphuration are listed and wet and dry desulphuration compared in tabular form. A former comparison of investment and operating costs for a 600 MW combination power station proves positive for dry desulphuration.
Möglichkeiten der Feuchtemessung bei verfahrenstechnischen Trocknungsprozessen
Authors: Freudenberger Adalbert
Published: December 2004

Moisture Measurement in Technical Drying Processes. Drying processes still have a large potential for optimization with respect to economy and uniform quality of the products. A necessary condition to improve these processes is the continuous availability of information about the water content of the product. Only in few cases a satisfactory solution of this problem has been found. In addition, the more simple moisture measurements of the exit air of dryers also involve numerous problems. This publication presents a survey of the different methods of moisture measurement together with the inherent problems. Finally it describes an arrangement for a humidity measurement of a flash‐dryer's exit gas by the infrared technique.
Integrierte Informationsverarbeitung im Anlagenbau
Authors: Schmidt‐Traub Henner
Published: December 2004

Integrated information processing in plant design. Characteristic for plant design is the cooperation of quite different engineering disciplines. The quality of the engineering therefore is influenced mainly by technical coordination and flow of information between these disciplines. Software applications for plant design are very often individually written systems. It is the aim of data integration to increase the quality of engineering besides the rationalization of work. Depending on existing software, individual solutions for data integration are predominant. These solutions have to correspond to iterative procedures during plant engineering. Object‐oriented CAD systems instead of only graphics‐oriented CAD software are an important condition for further data integration. However, in order to utilize these advantages for exchanging electronically stored documentation between different companies, all interfaces and data structures have to be publicly available.
Meßtechniken für Gas/Feststoff‐Wirbelschichtreaktoren
Authors: Werther Joachim , Hartge Ernst‐Ulrich , Rensner Detlef
Published: December 2004

Measuring techniques for gas/solid fluidized bed reactors. Significant progress has been made in the field of fluidization in recent years due to its application to the combustion of coal as well as sewage sludges and other residues. The new applications have also created a demand for new measuring techniques. In the present paper the available measuring techniques for fluid mechanical properties are reviewed, ranging from simple measurements for the determination of bed expansion to more sophisticated techniques for the determination of local solids concentrations, velocities, and mass flows. Furthermore, the problem of gas sampling from fluidized bed reactors is discussed. Among others, a measuring technique based on mass spectrometry is presented for local and instantaneous measurements of gas concentrations.
Methoden und Anwendungen der statistischen Prozeß‐ und Qualitätskontrolle im chemischen Betrieb
Authors: Kreitner Hermann , Kersting Franz‐Josef , Schuler Hans
Published: December 2004

Methodology and applications of statistical process and quality control in chemical plant. Statistical process and quality control, known respectively as SPC and SQC, presently command considerably attention. Originating with buyers of chemical products, the vocabulary and methodology of this area of expertise are increasingly entering the chemical plant. Appropriate use of these techniques is considered in the present article. A brief presentation of the philosophy of quality assurance in production using the methods of SPC and SQC is followed by a terse explanation of the goals and techniques of SPC/SQC. The applicability of the methods to process engineering is a special problem. Questions of the necessary adaptation and introduction into the conventional procedures of process control are discussed. Instrumentalization of plant with digital process controllers provides a framework for implementation of integrated solutions of such quality assurance systems in production. This is explained with the aid of examples.
Instantisieren pulverförmiger Lebensmittel
Authors: Schubert Helmar
Published: December 2004

Instantisation of powdered foods. Instantisation of powdered substances is a form of special technical treatment designed to make the particles dissolve or disperse faster in liquid than the untreated product. This article presents the principal processes for instantising foods, compares their advantages and disadvantages, and discusses them with the aid of examples. In this instantisation of foods it is important to note that additives for improving wettability are used only in limited quantities or not at all, and that aroma components are frequently present which should be preserved unchanged in the product as far as possible. Developments accounting for these demands are shown. Instantising is intended to improve properties which are grouped together as instant properties. Methods used for measuring instant properties are shown and fast method is presented. Depending upon the question raised, it may be necessary to employ different measuring methods. An overall property is appropriate for assessing an instant product; such a criterion can be made up of individual properties such as wettability, dispersibility, and solubility. If an instantisation process is to be assessed or improved, then the individual properties are of interest. Results obtained so far and a simple theory provide information about the most favourable agglomeration size and porosity. The paper concludes with a discussion of the special difficulties encountered in the instantisation of strongly swelling foods and in the determination of their instant properties.
Anwendung der Ähnlichkeitsgesetze bei vollständiger und partieller Ähnlichkeit
Authors: Stichlmair Johann
Published: December 2004

Application of similarity laws in cases of complete and partial similarity. Application of similarity laws frequently permits solutions of difficult problems with the aid of simple model experiments. The first part of this contribution presents the fundamentals of similarity and the limitations which have to be considered in the conception of simple model conditions. The second part demonstrates the application of similarity laws in the case of complete similarity. Since the limitations applying to the conception of model experiments often preclude maintenance of complete similarity, the third part of the article develops strategies for model transfer for partial similarity. The potential of these strategies is demonstrated for several examples from process engineering.
Noch mehr Vorschriften – der Umwelt zuliebe?
Authors: Weizsäcker Ernst Ulrich Von
Published: December 2004

Even more regulations – for the sake of the environment. The flood of environmental regulations will continue to swell. Man's rape of nature will not be stopped by a hunt for pollutant nanograms. A gentle ecological tax reform holds more promise. It could trigger the structural change leading to a welfare model which could benefit the whole of mankind without destroying the earth. Nature‐conserving industries and technologies would attract investors. They would move over to the „sunrise side”︁ of the economy. The change of structure would be characterized by an „efficiency”︁ revolution in dealing with natural resources. Environmental protection will be transformed from a cost factor to a benefit factor. A broad social concensus comes into view.
Grenzflächeneffekte bei der Fest/Flüssig‐Trennung
Authors: Roth John‐Edwin
Published: December 2004

Interfacial effects in solid‐liquid separations. In this survey the nature and origin of interfacial effects in finely dispersed suspensions are explained. Their influence upon conventional process steps in solid‐liquid separation is discussed. Examples of technical applications of electrokinetic effects in separation processes are reviewed. The state‐of‐the‐art in solid‐liquid separation is characterized by qualitative knowledge about the effects of interfacial phenomena and empirically based electrokinetic separation processes. Knowledge is still insufficient for quantitative calculation of real processes or proper design of technical equipment. The field between interfacial physics, physical chemistry of surfaces and chemical or process engineering is interesting and far‐reaching. If the preceding step of particle generation by precipitation or crystallization is included in a comprehensive research program, a better understanding and a systematic use or prediction of electrokinetic interfacial phenomena in solid‐liquid systems can be expected.
Oberflächenbehandlungen zur Verbesserung der Gebrauchseigenschaften nichtrostender Stähle in der Chemietechnik
Authors: Protogerakis Emmanuil
Published: December 2004

Surface treatment for improving the properties of stainless steels used in the chemical industry. Stainless steels are only able to meet the corrosion resistance demands made on them if their surfaces are in an entirely satisfactory passive state. The final step in fabrication must therefore consist of surface treatments that optimize the performance properties of the parts. Various surface treatment processes are available for stainless steels: pickling, blasting, grinding and brushing. The two last‐mentioned processes are open to objections. Therefore, the main alternative to pickling, which is becoming increasingly problematical for evironmental reasons, is blasting. Provided blasting is carried out with a suitable abrasive (glass beads) and under optimized conditions, it is capable of cleaning the surfaces of the parts entirely satisfactorily.
Polymerisation im Kunststoffbetrieb: Kontinuierliche Polymersynthese und direkte Weiterverarbeitung
Authors: Michaeli Walter , Berghaus Ulrich , Speuser Georg
Published: December 2004

Polymerisation in plastics plants: continuous polymer synthesis and direct processing. Use of an appropriate machine concept and a suitable process strategy permits combination of the advantages of anionic moulding masses known from monomer moulding with the advantages of continuous extrusion process. Moreover, coupling of reactive extrusion with direct processing has technically and economically interesting application owing to the low price of raw materials and flexibility with regard to material properties. The molecular structure of the products can be varied within wide limits by way of the formulation of the reactive system. Suitable process engineering can yield molecular masses greater than those of commercially available hydrolytic polyamide moulding masses. The authors' studies and analysis showed the polyamide products produced by reactive extrusion to have properties comparable with those manufactured from commercially available moulding masses.
Möglichkeiten zur Bodensanierung
Authors: Franzius Volker
Published: December 2004

Possibilities of soil clean‐up. Abandoned hazardous sites are abandoned waste sites or industrial sites which threaten human health, the environment, or other aspects of public safety. The enforcement of clean‐up of abandoned hazardous sites lies with the Federal German States. Registration and evaluation programmes are underway. Up to now nearly 50 000 suspected sites are registered in the former States of the Federal Republic of Germany and nearly 28 000 in the new states. Calculations of more than 100 000 suspected sites have been made. Several techniques are available for clean‐up which had been funded within the framework of numerous R&D‐programmes. The clean‐up technologies operating in praxis include thermal treatment, physico‐chemical treatment (soil washing and soil venting), and biological treatment. Future trends focus on combined treatment technologies in soil treatment centers.
Von Apollo zu Prometheus und Herakles: Ziele und Methoden der chemischen Verfahrenstechnik
Authors: Prausnitz John M.
Published: December 2004

From Apollo to Prometheus and Hercules: Objectives and methods of the chemical process engineering. The objectives and the methods of process engineering can be illustrated by comparison with three figures from Greek mythology: Apollo, the spirit and patron of scholarship, particularly philosophy; Prometheus, visionary in the application of ideas, who stole fire from the gods to use it in the service of mankind; and Hercules, who on behalf of all slayed the dragons which tormented mankind. Classical philosophy provides the historical foundation for process engineering (rational thinking which brings order to the chaos of nature); in the same way, contemporary philosophy can serve as the basis for the definition of the role of process engineering in present day society. The central message of modern philosophy (hermeneutics) is the softening of boundaries and devaluation of differences in methods of cognition; reconciliation between the sciences and society, and emphasis of horizontal rather than vertical thinking. These philosophical concepts have direct implications for the training of process engineers and for the development of new chemical products and processes.
Beratungssystem für die Trennung engsiedender und azeotroper Gemische
Authors: Simmrock Karl Hans , Fried Andreas , Welker Rüdiger
Published: December 2004

Expert system for the separation of closely boiling and azeotropic mixtures. The formation of azeotropes or the occurrence of closely boiling components in a mixture precludes straightforward rectification as a method of separation. Instead, recourse must be taken to special distillation processes which overcome distillation barriers by admixture of auxiliary substances or exploitation of system‐inherent properties. While the choice of suitable auxiliary substances is almost the only decisive factor in the design of extractive rectification processes, it is difficult to gain an overall view of the numerous variants possible owing to the different distillation properties of azeotropic mixtures. A sound approach is offered by the use of heuristic knowledge in the form of a knowledge‐based expert system to establish the number of possible alternatives satisfying the present state of the art. Starting from a small number of readily available substance and mixture data, rectification processes suitable for the separation of closely boiling or azeotropic mixtures are selected and the corresponding process structures are generated. If necessary, the system initially suggest suitable auxiliary substances satisfying the demands of the special process in question. This paper presents a detailed description of the construction of the expert system for the choice of auxiliary materials and process generation, subdivided into pressure change, homoazeotropic, heteroazeotropic, extractive and multiple azeotropic rectification, the procedural strategy, and the explanatory components of this expert system.
Reaktions‐ und verfahrenstechnische Aspekte der Heterogenisierung homogen‐katalysierter Synthesen
Authors: Luft Gerhard
Published: December 2004

Reaction and process engineering aspects of transforming homogenous catalytic syntheses into heterogeneous processes.In order to avoid the separation of the catalyst in homogeneous catalytic processes, the preparation of supported phase catalysts has attracted widespread attention in recent years. Most interest has focussed on the immobilization of transition‐metal complexes on solid supports for catalyzing carbon monoxide and olefin reactions. After a survey of the development of solid supported phase (SSP)‐ and supported liquid phase (SLP)‐catalysts two reactions in which SSP‐catalysts have been applied are considered in detail: The carbonylation of methyl acetate to acetic anhydride and the stereoselective hydrogenation of 2‐acylaminocinnamic acid to (S)‐phenylalanine, a derivative ofL‐DOPA. In order to discuss the favourable characteristics and the disadvantages of SSP‐catalysts, they are compared to soluble catalysts. Furthermore, the design of both processes is discussed.
Plattieren — eine kostengünstige Alternative für den Einsatz metallischer Werkstoffe in der Chemietechnik
Authors: Horn Elmar‐Manfred , Korkhaus Jürgen , Mattern Paul
Published: December 2004

Plating – a cost‐effective alternative to the use of metallic materials in chemical engineering. The paper treats plated semifinished products used in chemical plant construction. Advantages and draw‐backs of various plating processes such as welding, rolling, or by detonation are discussed as well as post plating processing such as hot forming or joining with regard to measures to be observed. Selection of the most suitable technique should be based on considerations of materials producers, workshops, and chemical plants.
Die Berechnung des Druckverlustes in der dreiphasigen Schwallströmung von Wasser, Öl und Luft
Authors: Herm‐Stapelberg Heinrich , Mewes Dieter
Published: December 2004

Calculation of Pressure Drop in Ternary Slug Flow of Water, Oil, and Air. Ternary flow of two immiscible liquids and a gas have hardly been studied up to the present although they frequently occur in petroleum production and in boiling mixtures of liquids. The article first considers known facts about the various kinds of binary flow as limiting cases of ternary flow with special consideration of slug flow. The article then reports new experimental results on ternary flow of oil, water, and air. The frictional pressure drop for ternary flow can be determined with the aid of known calculation procedures valid for binary flow. The limits of the observed forms of flow can be read from a flow map extended to include ternary flow. The pressure drop of ternary slug flow cannot be calculated without a knowledge of the form of flow. The frequency of slug movement is calculated for ternary flow by considering the pressure drop on binary flow of oil and water and the modified slug formation of liquids with higher viscosity. For small volume flows of gas the slug is almost ungassed. The pressure drop can be calculated with considerable accuracy in this range. At higher gas volume flows this becomes possible on considering measured slug lengths.
Entwicklung eines Simulationsprogramms zum Scale‐up von Hydrierreaktoren
Authors: Greger Manfred , Gutsche Bernhard , Jeromin Lutz
Published: December 2004

Development of a simulation program for the scale‐up of hydrogenation reactors.The scale‐up of trickle‐bed reactors to pilot and production scale has been difficult and necessitated considerable over‐dimensioning. Therefore a simulation program based on a cell model has been developed in which the dimensions of a cell are directly related to the dimensions of the catalyst particles used. The kinetic equation is formulated with an effective rate coefficient as the only key parameter to be adjusted. With this coefficient the intrinsic rate coefficient, the mass transfer, and the incomplete catalyst particle wetting are considered. The model was applied to the hardening of fatty acids and the hydrogenation of fatty acid methyl esters in laboratory reactors. Comparison with experimental results of pilot and industrial scale is favourable. Thus the model can be used for the scale‐up of trickle‐bed reactors.
Das Zerstäuben metallischer Schmelzen
Authors: Bauckhage Klaus
Published: December 2004

Atomization of metallic melts. Among the numerous atomization techniques for melt spraying the principal ones are described and discussed in regard to their design criteria and operating conditions. They can be classified according to the forces acting on the melt stream via the high energy fluid streams (gas or water jets), by ultrasound‐activated vibrations, by impact on by rotating elements. The equations for overall drop size distributions will be discussed. This information is important for optimized production of powders, especially if the median diameters of the resultant particle size distributions are correlated with the operating parameters of the disintegration process. However, this message remains insufficient if no information is given about its standard deviation with regard to the typ of distribution.
Stand der Entwicklung von Füllkörpern und Packungen und ihre optimale geometrische Oberfläche
Authors: Billet Reinhard
Published: December 2004

Development of Packings and Their Optimal Surface Geometries – State of the Art. There is a growing demand in industry for contact elements of the kind used in mass and heat transfer processes. It has been responsible for further development of established forms of packing and for new developments in packed beds arranged at random or in fixed geometric patterns. Comprehensive experimental and theoretical studies have revealed the factors that decide the performance of these packings and the limits of their development. It can thus be clearly demonstrated that technical measures impose limits on the improvements in efficiency that can be achieved. On the basis of costs considerations, combined with the results of performance studies, the paper shows how optimum geometric area of a dumped or arranged packings can be determined.
Materielles Recycling thermoplastischer Kunststoffabfälle
Authors: Michaeli Walter , Bittner Muna
Published: December 2004

Material Recycling of Plastics Waste. The recycling of plastics waste comprises of two main steps, viz. waste preparation and melt processing. Depending on the quality of the waste input and the desired product, the various recycling processes differ considerably in these two steps. For mixed and contaminated plastics wastes, processes are available which, with minimum preparation, process the melt into thick‐walled products. Better defined plastics wastes on the other hand are treated with greater investment in preparation and are generally processed with extrusion into granules for normal plastic processes. Preparation includes shredding, washing and drying, sorting, and agglomeration.
Die Aceton‐Butanol‐Gärung: Grundlage für einen modernen biotechnologischen Prozeß?
Authors: Dürre Peter , Bahl Hubert , Gottschalk Gerhard
Published: December 2004

Acetone‐butanol fermentation: basis of a modern biotechnological process? Acetone‐butanol fermentation was performed on a large industrial scale for about forty years. After the Second World War it was unable to compete with petrochemical processes and renewed interest in this fermentation has developed only during the last decade. It has led to a vast increase of our knowledge of the biochemistry of acetone‐butanol formation and of the genetics of the producing organism, Clostridium acetobutylicum. Considerable progress was also made in defining optimal fermentation conditions. However, the biotechnological process is not yet economically feasible, primarily because low final product concentrations engender high product recovery costs.
Erfahrungen mit Mehrproduktanlagen
Authors: Schuch Gunter , König (Fh) Josef
Published: December 2004

Experience Gained with Multipurpose Plants. Multipurpose plants are used in many fields of production. Some products often have a short life cycle or are not in continuous demand; hence these plants undergo constant changes. In order to control these changes from an economical point of view, certain boundary conditions must be met. The following article describes which questions have to be asked and answered and which structures prove to be advantageous for such plants.
Dynamik durchgehender Reaktionen in durchmischten Systemen
Authors: Schuler Hans
Published: December 2004

Dynamics of runaway reactions in well‐stirred systems. The dynamics of the course of reaction plays a prominent role in the safety assessment of chemical reactions: A controlled reaction course differs in essential dynamic features from a runaway reaction. In this contribution the safety assessment of chemical reactions in well‐mixed systems are discussed from the process‐dynamic point of view. The theory of heat explosion, as well as specific parts of chemical reaction engineering, are considered from the process‐dynamic standpoint. The theory of heat explosion, as well as specific topics of chemical reaction engineering are included in this presentation.
Wertstoff‐Rückgewinnung durch Rektifikation und Extraktion
Authors: Villeumier Hartmut , Schlegel Jürgen , Burckhart Rüdiger
Published: December 2004

Wenn flüssige Nebenströme, hochbelastete Abwässer, verunreinigte Lösungsmittel und Desorbate aus Abluftreinigungsanlagen der Verbrennung zugeführt werden, entsteht zusätzlich zu den Entsorgungskosten auch noch der Wertverlust der enthaltenen Wertprodukte. Da es bei den meisten Produzenten oder Verarbeitern wirtschaftlich und betriebstechnisch ungünstig ist, die bei ihnen anfallenden Gemische selbst aufzuarbeiten, ist das Konzept einer zentralen Aufarbeitung bei einem erfahrenen Lohnverarbeiter wirtschaftlich und ökologisch die beste Lösung zur Vermeidung von Abfällen und für ein sinnvolles Recycling von Wertstoffen. Die Arbeitsweise eines solchen Lohnverarbeiters wird im einzelnen dargestellt und durch Beispiele erläutert.
Forschung in Verfahrenstechnik/Chemieingenieurwesen – Schwerpunkte und Entwicklungstendenzen
Authors: Blaß Echkart , Dialer Kurt
Published: December 2004

In der zweiten Hälfte der 80er Jahre führten auf nationaler und internationaler Ebene Analysen und Empfehlungen für notwendige Forschungs‐ und Entwicklungsaktivitäten zu mehreren Reporten. In der vorliegenden Übersicht werden Zustandekommen, Absichten und Beurteilung dieser Reporte dargelegt sowie ihre Themengebiete und Forschungsziele kommentiert. Es zeigen sich auf dem Gebiet des Chemieingenieurwesens nur wenige Überschniedungen, da die Reporte aus verschiedenen Blickwinkeln ausgearbeitet wurden. Auf dem Gebiet der technischen Chemie erweist sich der DECHEMA‐Report als der umfassendste und ergiebigste. Da er vor allem die chemische Forschung behandelt, wird er hier nur kurz angesprochen. Ein Überblick über tatsächlich beforschte Fachgebiete beschließt die Arbeit.
Nutzung von CO2 aus Rauchgasen für chemische Synthesen
Authors: Kessler Birgit , Eysmondt Jörg Von , Merten Heinrich
Published: December 2004

In diesem Beitrag wird diskutiert, ob durch chemische Verwertung von Kohlendioxid (CO2) aus Rauchgasen die CO2‐Emissionen konventioneller Kohlekraftwerke deutlich gesenkt werden können. Die möglichen Synthesewege zur Verwertung von CO2 und CO (aus CO2 gewonnen) werden anhand von Massen‐ und Energiebilanzen bewertet. Demnach können über chemische Synthesewege nur relativ geringe Mengen an CO2 gebunden werden, da die Jahresproduktionsmengen der in Frage kommenden Chemikalien (z. B. Harnstoff, Essigsäure und Methanol) im Verhältnis zur emittierten Kohlendioxid‐Menge unbedeutend sind. Die endotherme Umsetzung von CO2 zu CO, das bereits in zahlreichen technischen Synthesen eingesetzt wird, erfordert den Einsatz fossiler Energieträger, was wiederum mit einer zusätzlichen CO2‐Emission verbunden ist. Aufgrund der vorliegenden Ergebnisse ist die chemische Verwertung von CO2 aus Kraftwerksrauchgasen bis auf weiteres keine aussichtsreiche Methode zur Senkung der CO2‐Emissionen.
Austragorgane und Austraghilfen
Authors: Schulze Dietmar
Published: December 2004

Feeders and Discharge Aids. Feeders and discharge aids have an influence on the flow behaviour of bulk solids in silos. Together with the geometric form of the silo, they are responsible for the operating conditions of a silo. Therefore, feeders and discharge aids have to be chosen and installed under consideration of the flow properties of the bulk solid to be stored. The necessary information is obtained by using the silo design method due to Jenike. This method yields the geometrical data of the hopper (wall steepness, outlet diameter) necessary for a troublefree operation (no doming and ratholing; mass flow; no segregation; uniform flow). Furthermore, the design of feeders and discharge aids plays an important role in determining their function. For example, stagnant zones will build up and cause flow problems on protruding edges and on walls which are not steep enough. For the correct function of the hopper/feeder combination it is important to make sure that the feeder fully activates the hopper outlet and stagnant zones cannot build up. This can be ensured by an appropriate feeder design (increasing capacity in direction of conveying). The driving power of a feeder has to be calculated also on the basis of the flow properties of the bulk solid to be stored.
Belagwachstum am umströmten Rohr
Authors: Riehl Ingo , Kaminski (geb. Heilmann) Silke
Published: December 2004

Growth of Deposits on Pipes in a Field of Flow. The deposition of ash particles on the heat pipes of steam generators represents an energy and safety problem. A deterministic single‐particle model was used to simulate this deposit formation. The numeric solution of the equation of motion gives the distribution of the impact points of the particles on the pipe surface. A particle mass balance allows calculation of the deposit formation δ (φ, t) on a pipe in space and time. Even if only a simple adhesion model is used, the calculated shape of the deposit can approach real deposit shapes. The effect of the sticking probability on deposit shape and formation time is shown. Numeric and analytical studies indicate the existence of stable limiting forms of the deposit. Thus, pipe forms can be calculated which allow only low levels of deposition and erosion. The model can be applied to particle‐fluid flows around other contours.
Ablauf durchgehender Reaktionen sowie Auswahl und Führung von sicheren Prozessen
Authors: Gustin Jean‐Louis
Published: December 2004

Runaway Reactions – Their Course and Methods for the Choice and Design of Safe Processes. Literature about runaway reactions is usually concerned with the consequences of explosions such as destruction and emission of hazardous and inflammable substances. DIERS literature describes methods for the design of relief orifices for which experimental studies are necessary. Only few data are available relating to the course of runaway reactions, which, more‐over, are also attributable to variety of causes. The present report describes the various process deviations which can trigger a thermal explosion. In addition, the determination of the necessary data and considerations for risk analysis and for the development of inherently safe processes and for lessening the consequences of thermal explosions are discussed. Any possible dangerous process deviation is illustrated with the aid of examples and experimental data obtained in laboratory experiments. The various dangerous process states which can lead to a thermal explosion are thus subjected to systematic study.
Werkstoffauswahl in der Chemischen Verfahrenstechnik
Authors: Gramberg Ubbo
Published: December 2004

Choice of Materials of Construction for Chemical Process Engineering. The choice of appropriate materials is of critical importance for the trouble‐free operation of chemical plant and for economic production. Questions of materials should therefore be considered at an early stage of process development. As a rule, the boundary conditions having a direct influence on the choice of materials are communicated by the process engineer to the materials scientist. Several approaches to the proper choice of materials are usually possible. This choice must ensure that adequate safety reserves are available without making the plant unnecessarily expensive. Although numerous methods are available for determining the properties of materials, testing under operating conditions for specific applications is the optimal approach. The experience amassed by materials experts in practice is an extremely important and indispensable factor because there is much knowledge which cannot simply be expressed in equations and numbers.
Erforderliche Informationsstrukturen für die Qualitätssicherung
Authors: Polke Martin
Published: December 2004

Information Structures Required for Quality Assurance. An information model „quality”︁ is developed on the basis of an object‐oriented structuring of the production process into the two object classes of „product”︁ and „process element”︁. The pertinent product and process properties are represented as set and actual values in property profiles. Particular attention is paid to the scaling necessary or possible for each value representing a property. The histogram has proved to be an appropriate method of representation. Changes in the product‐describing properties occurring during the production process are shown. The information structure selected permits definition of a quality assurance concept and the information and equipment necessary for its implementation.
Umrüstung auf Membranzellen in der Alkalichlorid‐Elektrolyse vor dem Hintergrund der FCKW/CKW‐Diskussion
Authors: Staab Rudolf , Bergner Dieter , Scheibitz Wolfgang
Published: December 2004

Conversion of Alkali Chloride Electrolysis Plant to Membrane Cells in the Face of the On‐going CFC/CHC Discussion. The environmental discussion on chlorine‐containing chemical products such as chlorinated hydrocarbons, chlorofluorocarbons and PVC is resulting in lower demand or even abandonment of production in certain areas. This in turn is leading to reduced production or even to the shutdown of alkali chloride electrolysis plants. In view of this general situation and the high capital expenditure required for switching from mercury cells to membrane cells, the change is not economically feasible despite the considerable savings in energy consumption it would bring.
Grundsätze der Qualitätsarbeit im Unternehmen
Authors: Sommer Ernst
Published: December 2004

Fundamentals of Quality Work in Companies. The new quality consciousness originating in Japan, and meanwhile adopted by the industrialised countries of the west, goes far beyond mere adherence to agreed technical criteria. All departments of a company are to be included in the quality assurance system in order to prevent errors from arising in the first place. The introduction of quality assurance systems must be instigated by top management and go down from there to all employees. Above all in the case of companies with highly complex structures, an internal customer‐supplier relationship should be developed which corresponds to that between the company and its customers. It makes good sense to incorporate existing activities into the quality assurance system. Since customer demands change with time, quality improvement must be approached as a dynamic process.
Die Entwicklung der Destillationstechnik im 19. Jahrhundert
Authors: Deibele Ludwig
Published: December 2004

Development of Distillation during the 19th Century. Up until the end of the 18th century distillation plant consisted only of an evaporation and a condensation unit. The rectification column is an invention of the early 19th century. This article surveys these developments and the advances in alcohol distillation made up to the end of the 19th century. Developements in France, England and Germany are considered separately since different starting materials were used for alcohol production in these three countries. In France the starting material was wine, in England grain, and in Germany potatoes. Wine could be fed directly to the rectification column. Grain first had to be transformed into grain mash before being transferred together with husks to the distillation apparatus. The highly viscous potato mash containing potato pieces and skins produced by a similar process proved particularly hard to handle. The widely varying properties of these raw materials led to development of different equipment in the different countries.
Tendenzen in der EG‐Umweltschutzgesetzgebung und Auswirkungen auf die chemische Industrie in Deutschland
Authors: Hezel Carl
Published: December 2004

Trends in the Environmental Legislation of the European Community and their Consequences for the German Chemical Industry. Environmental legislation from the EC has changed considerably in recent years. The directives of the early eighties contained mainly general guidelines and generous limit values. Due to the need for unanimous voting for the decisions stricter thresholds were not achievable. They had relatively small impact on Germany because that country's internal legislation was more stringent. There is now a new trend which gives cause for concern. Many elements of the latest directives do not match the German legal system and lead to stringent conditions. This is due to the fact that they have to be implemented in addition to existing legislation: Much written information and evidence of performance are required, relating to e.g. the installations and the management of the company. As a consequence there will be further complications in the approval procedure for chemical plant.
Persönlichkeitsbildung durch das Studium
Authors: Stephan Karl
Published: December 2004

Personality Development through University Studies. At present universities are often accused of contributing insufficiently to the personality education of their students. There is a demand for a more comprehensive personality education during university studies. This runs counter to contradiction to demands for a shorter duration of studies, because personality education takes time. This paper examines what personality education means and to what extent the study of engineering sciences can contribute to it. It demonstrates that the study of engineering disciplines imparts many values contributing to the personality education. Some other features of the development of a person are embedded in the structure of that person and can only be communicated in part through education. Engineers are usually not well trained to assess the social consequences of their technical actions. It is therefore suggested that some universities concentrate on the education of generalists who acquire a broad knowledge in the engineering sciences and a high social competence.
Prototyp eines wissensbasierten Programmsystems für die Systemsimulation
Authors: Eickhoff Jens , Futterer Eberhard
Published: December 2004

Prototype of a Knowledge‐Based Program System for System Simulation. The present article describes a new approach for merging numeric simulation techniques and knowledge‐based methods for process simulation. In a first step the potential of such a combined technology is outlined, concerning both knowledge‐based user support in handling and application of simulation codes as well as the support of the engineering task for chemical process development. An analysis of implementation techniques outlines, how an adequate integration of numeric and knowledge‐based software modules can be achieved by adoption of the object oriented programming paradigm. The resulting requirements for the modelling of knowledge and the corresponding inference mechanisms are explained and a software prototype is presented by which this knowledge‐based simulation technology is currently being evaluated and refined using a case study from aerospace domain.
Entwicklungen bei der Lösungskristallisation in den letzten Jahren
Authors: Ulrich Joachim
Published: December 2004

Recent Developments in Crystallisation from Solution.Although there have been no great leaps forward in the design of plant for crystallisation from solution in recent years, our understanding of growth rate dispersion, the extension of the two‐step model of crystal growth to a three‐step model when required, and also convenient modelling approaches for crystal morphologies and the development of tailor‐made additives have nevertheless greatly advanced our knowledge of crystallisation processes. Substantial divergencies in the measured values of crystal growth rates in the past decade can often be explained by paying due attention to the measuring methods and the purity of the substances as well as the nature of the solvent. Comparison of results obtained by modelling should always prove more satisfactory when heat effects are considered whenever this is necessary. The possibilities of crystallisation plant design are greatly enhanced by the availability of reliable data as a basis for calculation and when influencing crystal shape can provide downstream processes with a better product.
Wandel in der Verfahrenstechnik — Anforderungen an die Ausbildung
Authors: Frey Walter
Published: December 2004

Chemical Engineering in a State of Change – Educational Requirements. The structural change taking place in the chemical industry will influence future requirements for chemical engineers and hence also the training of these engineers. Owing to the advancement of the knowledge base of chemical enginnering, greater emphasis will in future be placed on substance‐orientation and a holistic approach. This will allow chemical engineering to enter new areas. There will also be greater demands for such additional abilities as teamwork sensitivity, and creativity. The training of chemical engineers should take account of these developments.
Kritische Anmerkungen zu den Werkzeugen der Verfahrensüberarbeitung
Authors: BeßLing Bernd , Ciprian Jürgen , Polt Axel , Welker Rüdiger
Published: December 2004

Critical Remarks on Tools for Process Revision. The revision of production processes is based on data, results and experience gained from a wide range of tools and instruments. It is therefore important to critically examine the limits and meaningfulness of these tools and instruments as they apply to process revision. Following a description of a normal revision procedure, the limits and meaningfulness of the information obtainable by modelling, experiment and full‐scale operation are discussed as a basis for process revision. Particular emphasis is placed on fundamental operational information obtained from production plant. In addition, tools specially developed for process revision are presented and evaluated. The common theme of these tools is the ability to provide improved material balances of operating processes. Some of the better known process evaluation tools are also considered. The main feature of these tools is the abstraction of the task of individual unit operations as a starting point for possible process improvements.
Schaum und Schaumzerstörung – ein Überblick
Authors: Pahl Manfred H. , Franke Dirk
Published: December 2004

Foam and Foam Breaking – A Review. Many technical processes produce foams which complicate the performance of a given process or even make it possible. Foam breaking, therefore, becomes necessary. This paper outlines well known and new methods of foam breaking as well as the breaking principles. For the example of sprinkling, the influence of selected parameters on the destruction efficiency and the formation of secondary foam can be demonstrated. After a discussion the properties of foam, stabilizing and destabilizing effects, possibilities of foam characterization and foam avoidance are presented.