bluuebunny/crossref_metadata_2025 huggingface dataset:
Erdöl‐Emulsionen — Eigenschaften, Stabilität und Spaltung
Authors: Neumann Hans‐Joachim , Paczyńska‐Lahme Barbara
Published: December 2004

Erdöl kommt immer zusammen mit Salzwasser vor und wird sehr häufig als Wasser‐in‐Öl‐Emulsion gefördert. Es sind Emulsionen mit mehr als 90% Wasser bekannt. Sie sind oft außerordentlich beständig. Die Viskosität der Emulsionen steigt überproportional mit dem Wassergehalt an und ist regelmäßig wesentlich höher als die nach der Einsteinschen Beziehung berechnete Viskosität. Die Erdöl‐Emulsionen sind durch Adsorption der in den Erdölen kolloidal dispergierten Asphaltene und Erdöl‐Harze stabilisiert. Diese bilden an den Wasser/Öl‐Grenzflächen mechanisch stabile Filme aus. Die Filme enthalten verschiedene anionaktive, kationaktive und amphotere Stoffe, die im Erdöl zu kolloidalen Micellen assoziiert vorliegen, und die aufgrund ihrer Grenzflächenaktivität an den Öl/Wasser‐Grenzflächen adsorbiert werden. Die Adsorptionsfilme sind von der Ölphase benetzt. Die Emulsionen sind koaleszenzstabil, nicht aber flockungsstabil. Emulsionsspalter verdrängen die Stabilisatoren von der Grenzfläche oder verändern ihre Benetzbarkeit.
Untersuchung von Heterogen‐Katalysatoren mit modernen Oberflächen‐Analysenmethoden
Authors: Mroß Wolf Dieter , Kronenbitter Johann
Published: December 2004

Study of heterogeneous catalysts by modern surface analysis methods. The past decade has been one of tempestuous development in methods of surface analysis as a result of significant improvements of vacuum techniques and electronic components. The principal methods available for studying the chemical composition of catalysts are ESCA, Auger spectroscopy, ISS (ion scattering spectroscopy), and SIMS (secondary ion mass spectrometry). The “classical scanning microscope” and various “micro‐range” analyzers, e. g. the scanning Auger microscope, permit elucidation of catalyst surface structures. Advantages and drawbacks of the various methods are presented with the aid of selected examples and the limits of the analysis of industrial catalysts are discussed.
Kennzeichnende Verfahrens‐ und Einflußgrößen beim katalytischen Fließbett‐Cracken
Authors: Knab Heiner , Mielicke Claus , Rosum Erich
Published: December 2004

Characteristic process parameters and variables in catalytic fluidized bed cracking. Catalytic fluidized‐bed cracking occupies a distinctive position among the various conversion processes. With regard to its favorable product range, the process is characterized by low processing costs coupled with flexibility of raw materials. A number of independent process parameters are available for control of the reactions involved in catalytic cracking and for influencing the product range. The cracking reactions taking place and the interplay of the independent and dependent variables are described. Apart from the actual cracking process, particular importance attaches to the regeneration of the catalyst charged with coke since it has a decisive influence on the thermal economy of the plant. Depending upon the desired product yield or the raw materials a suitable catalyst must be chosen. Considerable progress has recently been made in catalyst development.
Gewinnung von Brennstoff für Kraftwerke aus Klärschlamm
Authors: Sander Bruno , Lauer Herbert
Published: December 2004

Production of a combustible for coal‐fired power stations based on sewage sludge. This article describes various means of achieving more extensive mechanical dewatering of sewage sludges. The heat content of the sludge solids can become available for combustion processes. The sludge filter cakes obtained by the “CarboSed” process can be disposed of with minimum energy consumption by fluidized bed combustion or be used after appropriate work‐up as a combustible in coal‐fired power stations with full exploitation of their heat content for generation of steam and electric current. Partial substitution of primary energy sources such as coal and fuel oil by sludge filter cake is feasible in all cases. The processes thus make a contribution to the saving of energy resources and the disposal of sludge.
Rechnerunterstützung bei der Rohrleitungs‐Konstruktion im 3D‐Raum
Authors: Bohle Detlef , Jakobs Gerhard , Hänisch H. Klaus , Kalbitz Harry
Published: December 2004

Computer‐assisted pipe routing in three‐dimensional space. For the past twelve years, the management of materials and the production of isometric drawings have been supported by computer programs. With the aim of expanding computer assistance, a long‐term joint systematic study of design activities during the planning of chemical plant performed by BASF and the engineering design department of the Technical University of Braunschweig has led on to a study of the use of computer graphics.
Zum Problem der Datendokumentation
Authors: Springe Wolfgang , Krüger Helmut
Published: December 2004

Some problems of numerical data documentation. Central data pools which fulfil most of the requirements of science and practice are both expensive and manpower‐intensive because of the vast quantities of data involved, uncertainty regarding material composition, disregarded parameter influences, insufficient reliability, and problems of copyright. A worldwide survey reveals the existence of a wide variety of data pools which are underused because they are not known. The paper cites literature listing such pools. One of the recommendations in the paper is to cooperate in transferring all available data of a material into its “data matrix” – thus exposing the gaps that are still left. This would be a relatively inexpensive step towards improved data supply.
Erleichterungen bei der Planung und Auslegung von Schüttgut‐Aufbereitungsanlagen am Beispiel der pneumatischen Förderung
Authors: Krambrock Wolfgang
Published: December 2004

Facilitating the planning and design of plant for working of bulk solids, as illustrated by pneumatic conveying. Taking the case of pneumatic conveying as an example, the article shows how plant construction companies can achieve considerable simplifications and time saving in the planning and building of plant for working of bulk solids by adopting a systematic approach utilizing card indexes of bulk materials and working diagrams. Companies operating such plant are made aware of the thorough preparation invested in new projects and of the approach adopted and problems encountered in the preparation of tenders. A simple general view of the present state of knowledge can possibly provide impulses for new considerations.
Benetzung und Stoffaustausch in Filmkolonnen
Authors: Hüttinger Klaus J. , Bauer Franz
Published: December 2004

Wetting and mass transfer in film columns. Calculation of mass transfer in film columns requires a fundamental knowledge about the wetting of the materials comprising the packing bodies. Starting from thermodynamic principles for a description of the solid/liquid interface, methods are discussed which permit an exact calculation of the basic parameters of wetting. It is also shown how the goal of ideal wetting can be approached by choice of material, modification of the surface of the packing bodies, and use of additives. Experience gained with regard to the effect of the various measures on the separation performance leads to conclusions concerning the determination of dimensionless equations for prediction of separation performance.
Zentrifugalextraktion – Eine Literaturübersicht
Authors: Gebauer K. , Steiner L. , Hartland S.
Published: December 2004

Centrifugal extraction – a literature survey. A survey of the different types of centrifugal extractors is presented. The construction details are given both for the common type of extractor and for less well‐known designs as encountered in the patent literature. The effect of a centrifugal field on hydrodynamics and mass transfer is also discussed theoretically, together with actual experimental measurements and techniques used in practice.
Zusammenarbeit von Industrie, Forschung, Technischer Überwachung, Lehre und der Rechtswissenschaft zur Erhöhung der technischen Sicherheit
Authors: Kremer Gottfried
Published: December 2004

Collaboration between industry, research, technical surveillance, teaching, and jurisprudence to increase the level of technical safety. An attempt is made to localize the difficulties occurring in the dialogue between the technologist and other groups in society representing far greater numbers, to show how collaboration proceeds between the many disciplines of technology, and what problems have to be solved together with lawyers, in order to permit technology continue to serve the wellbeing of society. It is hoped that this account will also stimulate fruitful discussions.
Zur Bedeutung der Störfall‐Verordnung
Authors: Pilz Volker
Published: December 2004

The significance of the breakdown ordinance. The justification, requirements, and possible consequences of the breakdown ordinance are discussed against a background of current practice in the chemical industry. Comparisons are made with other countries and nuclear engineering. These considerations lead to the conclusion that the ordinance has not generated new standards in technology but, as a result of the enormous information and documentation demands, material, political, and economic disadvantages are to be feared for the chemical industry in West Germany.
Sicherheitstechnische Überlegungen des Anlagenbauers und des Betreibers
Authors: Tröster Erwin
Published: December 2004

Safety considerations of plant constructors and operators. Regular reviews of safety at predetermined intervals and with due regard to actual issues are proven means of ensuring the necessary high level of safety of chemical plants. Practical procedure and correlation with the design schedule of plants at a large chemical company are described.
Modellrechnungen zu Explosionen freier Gaswolken von Kohlenwasserstoff/Luft‐Gemischen
Authors: Ebert Fritz , Becker Thomas
Published: December 2004

Model calculations on the explosion of free gas clouds containing mixtures of hydrocarbons and air. The procedure presented permits a description of continuously and discontinuously accelerated explosions. The explosions considered are deflagrations, i. e. combustion‐supported compression waves. It is possible to calculate, for a given rate of propagation of a flame front or the motion of a piston assigned in a model, the corresponding flow field (compression wave). The corresponding pressure, density, and velocity distributions can be utilized for safety considerations. Application of the results requires that the simulated acceleration processes can be transformed into real events. With the experimental results presently available this is possible only in very crude fashion and can serve only as a rough preliminary guide.
Rheologische Aspekte in der Verfahrenstechnik
Authors: Schümmer Paul
Published: December 2004

Rheological aspects in process engineering. As continuum mechanics tailored to engineering problems rheology first tries to describe the phenomena observed with rheologically complex materials in terms of rheological equations of state. In so doing, material parameters or material functions are defined, in which the material characteristics are established. To classify or predict properties, the physical structures of materials are correlated with the phenomenological rheological characteristics with the help of statistical methods. A clear description of complex experimental results can be accomplished by combining the variables to form dimensionless variables. Besides the „classical”︁ dimensionless variables there are also others which, however, entail restrictions regarding the possibility of ideal model experiments. It is sometimes advantageous to use material functions instead of material parameters in the dimensionless variables.
Neuartige Batterie‐Systeme
Authors: Beck Fritz
Published: December 2004

New battery systems. The reversible storage of electrical energy plays a central role in the development of electric vehicles, load levelling in power stations, and technical utilization of solar energy. Electrochemistry offers interesting solutions with optimal energy density; however, these have reached technical maturity in only a few cases. The conventional lead/acid accumulator is being further improved among aqueous systems. Moreover, various other lines of development have been initiated in recent years, such as nickel/zinc and chlorine/zinc accumulators, which offer totally fresh perspectives from an electrochemical and engineering point of view. In the case of zinc/air and aluminium/air batteries, external redeposition of the metal is envisaged. From a practical point of view, aqueous systems are unsurpassable. Metals with an extremely high negative potential like sodium or lithium can only be cycled in the absence of water. Systems with molten salts or solid electrolytes do not suffer from this drawback. The sodium/sulfur battery, which is characterized by readily available cell components of low environmental impact, is presently undergoing intensive development. However, thermal discharge represents a technical problem. The future of these new developments will be governed by their economics, energy density, energy efficiency, power density, and last but not least by their cyclability. These properties have not yet been optimized in a single system.
Elektrochemie mit dreidimensionalen Elektroden
Authors: Kreysa Gerhard
Published: December 2004

Electrochemistry with three‐dimensional electrodes. Three‐dimensional electrodes such as are used in fixed‐bed and fluidized bed electrolysis are suitable for purifying waste water containing heavy metals and for metal recovery from dilute solutions, and also open up new possibilities for electrochemical purification of waste gases. An account of the theoretical principles of the macrokinetics of these systems is followed by descriptions of a waste‐water purification process by fixed bed electrolysis, which is already in industrial use, of the rotating fixed‐bed electrode, and of the state of the art of fluidized bed electrolysis for production of metals. An electrochemical absorption tower permits removal of chlorine and sulphur dioxide from waste gases.
Wasserstoff‐Erzeugung und Kreislaufgas‐Zerlegung für die Kohleverflüssigung
Authors: Becker H. , Brauer O. , Heucke C. , Lohmüller R. , Ranke G.
Published: December 2004

Hydrogen generation and recycle gas separation for coal liquefaction. Just as 40 years ago, low‐temperature processes are now again being considered for recycle gas separation in today's large scale coal liquefaction projects. Hydrogen can be generated by gasification of heavy residues and by steam reforming of ethane. Alternatives for recycle gas separation into hydrogen and gas products are butane and methane absorption or low‐temperature condensation processes at high or medium pressure. These processes employ several additional absorption and adsorption steps for gas purification. They are proven on a large technical scale, and fulfill the requirements of environmental legislation.
Herstellung von Tränkkatalysatoren als verfahrenstechnische Aufgabe
Authors: Kotter Michael
Published: December 2004

Production of impregnated catalysts as a chemical engineering task. Impregnated catalysts are the result of manufacturing processes involving a complex interplay of diffusion, viscous flow by capillary action, and solid state reactions. A knowledge of physical chemistry and drying technology permits systematic prediction of the necessary production steps in some detail. It is similarly possible to reduce the number of experiments needed to determine which variables are important and therefore have to be optimized. Thus it is at least possible to distribute the active components in the structure of the carrier in a manner that relates appropriately to the reaction requirements. This systematic prediction is limited in special cases where the active component of the catalyst changes its chemical nature during production. An example of this is when a catalyst requires an activation step.
Thermische Behandlung von Sonderabfällen
Authors: Heitmann Aloys
Published: December 2004

Thermal treatment of special wastes. The incineration of waste is a proven process with known ecological consequences and is economically viable especially for large scale plant. The original ambitious objectives of the pyrolytic process have been considerably revised after the developments in this area failed to live up to many expectations or were found to be economically non‐viable. The combustion of chlorinated hydrocarbons on the high seas is ecologically safe. The processes discussed in this paper demonstrate that the development of thermal processes for the treatment of industrial wastes is by no means complete. This also applies to numerous other processes not discussed here.
Abfallbeseitigung auf See — Stand und Tendenzen
Authors: Schmitt‐Tegge Jan D.
Published: December 2004

Waste disposal at sea – state of the art and developments. The article starts by describing the legal situation governing the disposal of waste at sea and then considers the licensing procedure according to the „Oslo‐London treaty law”︁. The Federal German Department of the Environment is also involved in this licensing procedure in that it is responsible for examining the possibilities of disposal on land. The quantities of material for disposal have been considerably reduced in recent years in all areas. The disposal of sewage sludge and of dilute acids (from the production of organic dyes and pigments) in the North Sea has now stopped completely. The amount of waste for disposal from TiO2 production has been greatly reduced and stepwise cessation is planned by the mid ‐1980's. The incineration of waste on the high seas has also been restricted and will also be stopped in the long term. The results of ongoing and completed research are reported.
Kostensenkung durch planmäßige Instandhaltung unter Berücksichtigung der erforderlichen Verfügbarkeit
Authors: Krüger Hanns‐Günter
Published: December 2004

Cost reduction by planned maintenance, paying attention to required plant availability. Availability, plant utilisation, plant safety and maintenance are interrelated. The intensity and degree of planning of maintenance has to be within given conditions – and reduction of the degree of planning can also lead to a remarkable cost reduction in maintenance. Planned maintenance signifies not only optimization of the above relations, but also the performance of work in a highest amount of planning. Because maintenance costs are largely personnel costs, the planning and control of work have to lead mainly to an increase of effectivity of maintenance personnel. The following examples and numbers may show how organisational and technical measures can effect an increase of planning possibilities, and hence a cost favourable situation.
Zum überflutungsverhalten zwei‐ und dreiphasig betriebener Rührreaktoren
Authors: Wiedmann Josef Anselm
Published: December 2004

The flooding behaviour of two‐ and three‐phase operating stirred reactors. The present state of research concerning the flooding behaviour of aerated fluids and suspensions is presented. The author's own investigations, undertaken partly on a semi‐technical scale (tank diameter D = 1.5 m) show the most important parameters of this undesirable aerated state during the operation of stirred reactors. For a given stirrer speed the superficial gas velocity, the tank size, and the fluid viscosity are important. Solid particles sediment out when flooding is reached. An objective measuring method for determining the occurrence of flooding was adopted.
Maßstabsvergrößerung chemischer Reaktionsapparate
Authors: Riekert Lothar
Published: December 2004

Scale‐up of chemical reactors. It was shown by Damköhler as long ago as 1936 that full similarity can not be achieved in the scale‐up of chemical reactors. The scale‐up process must therefore either be undertaken by trial and error or it must be based on calculation, i.e. on a mathematical model. The computation requires kinetic data as input, which can only be obtained from experimental observations. The very fact that only reactor behaviour can be observed in the laboratory requires that the physical model and its mathematical formalization must be used twice: Once for „back calculation”︁ of kinetic data (coefficients) from the observed behaviour of the laboratory reactor and then again to predict the behaviour of a full scale reactor on the basis of these data. This procedure is of limited reliability due to the interaction of transfer processes (like heat transfer) at the boundaries of the system and relaxation processes in the bulk (like chemical reaction). These interactions may influence the kinetics in a way that cannot be predicted from theory or experiment. Damköhler's dilemma cannot be resolved through computation.
Wasserstoff‐Produktion aus Kohlenwasserstoffen. Fortschritte und Entwicklungstendenzen bei Synthese und Reinigung
Authors: Lohmüller Reiner
Published: December 2004

Production of hydrogen from hydrocarbons. Hydrocarbons are the preferred starting materials for the industrial production of hydrogen. Most hydrogen is produced by steam reforming of light hydrocarbons. Partial oxidation of heavy oil and residue is used for the production of H2 and synthesis gas in large plants. In both cases gas purification was improved. Hydrogen‐rich gases like coke oven gas, refinery‐offgas, and offgases from the chemical and petrochemical industry have high potential for becoming a major source of hydrogen. Processes for recovering H2 (and by‐products) are condensation and rectification at low temperatures and, most attractive and versatile for the production of very pure H2, adsorption (PSA). The environmental impact of H2 production lies mainly in the emission of CO2 and heat. Other forms of pollution can be considerably reduced by conventional methods. The economy of H2 production depends essentially on price and availability of the raw materials.
Die Elektrodialyse — ein Membranverfahren mit vielen Anwendungsmöglichkeiten
Authors: Strathmann Heiner , Chmiel Horst
Published: December 2004

Electrodialysis – a membrane process with considerable scope. Electrodialysis is a process by which electrically charged membranes are used to separate ions from an aqueous solution by the driving force of an electrical potential difference. Electrodialysis is used today mainly for desalination of seawater and brackish water. Other applications, such as the recovery of water and valuable metal ions from industrial effluents, the removal of salts and acids from pharmaceutical solutions and in food processing have only recently generated a broader interest. In this paper the principle of electrodialysis is described and the various parameters determining the technical feasibility and the economies of the process are discussed in more detail. Examples are given for the use of electrodialysis in the food and drug industry and in advanced waste water treatment. Finally, recent developments and future prospects of electrodialysis and related processes are discussed.
Behandlung sowie Beseitigung der bei Lagerung und Verladung brennbarer Flüssigkeiten entstehenden Dämpfe
Authors: Schwefer Hans‐Jürgen , Weyer Horst
Published: December 2004

Handling and removal of vapors generated on storage and loading of inflammable liquids. On storage and loading of liquid mineral oil products of high vapor pressure – e.g. gasoline and aromatic hydrocarbons – significant quantities of hydrocarbons will be lost. Mixtures with air can be inflammable. The limits of flammability of the three‐component mixture of burning gas, oxidizer, and inert gas can be described in a diagram. The occurrence of inflammable mixtures in recovery and combustion plants can be reduced by appropriate measures. The hydrocarbon content in waste gases of recovery plants can be reduced to few grams per cubic meter. The limits for emissions defined in the „Technische Anleitung zur Reinhaltung der Luft”︁ (TA Luft) generally can only reached by thermal oxidation. Two plants are presented, in which vapors of mineral oil products are handled and combusted.
Wirtschaftliche Gesichtspunkte bei der Auslegung von Wärmeaustauschern
Authors: Kern Jochen
Published: December 2004

Economic aspects of heat exchanger design. The economic design of a heat exchanger results in the minimum total cost over the expected lifetime. This needs a balance between the two groups of costs, capital investment and running costs. However, a general quantitative description of these cost groups is not possible due to the large number of variables, in practice one is limited to approximating analyses. In some cases a mere capital cost minimization will suffice; often, however, operating costs due to pumping power or price of heat have to be considered additionally. Further, it is important to note that the annual operating hours and the plant availability cannot be predetermined exactly and yet have a large effect on total cost. Therefore, and since one cannot take into account all the optimization parameters, one has to examine each individual case and devise a rational optimization routine. This paper illustrates the various levels of optimization and should facilitate the selection and hence promote the economic design of heat exchange equipment.
Ursachen und Auswirkungen der Verschmutzung und Verkrustung von Wärmeübertragungsflächen
Authors: Schnell (Fh) Heinz , Slipcevic Boris
Published: December 2004

Causes and effects of fouling and scaling of heat transfer surfaces. Fouling and scaling of heat transfer surfaces may lead to considerable performance losses of heat exchangers. During design compensation is made by overdimensioning based on estimated fouling factors, with varying degrees of success. A proper knowledge of the causes of fouling and of the time dependency of the fouling resistance would be better because the fouling effect could then adopting limited by reasonable preventative measures. At present, continuously operating cleaning systems are predominantly applied. A general description of the fouling process – deposition and removal – would require an analytic fouling model.
Niederdruck‐Polyethylen: Einfachere Verfahren durch hochaktive Katalysator‐Systeme
Authors: Böhm Ludwig
Published: December 2004

High density polyethylene (HDPE): simple processes with high mileage catalysts. Introduction of highly active catalytic systems considerably simplified the technical processes for polyethylene production with transition metal compounds (Ziegler process). The requirements for these catalysts are discussed and experiments and models are presented to show how these catalytic systems work in the industrial process. These investigations demonstrate that it is our detailed knowledge of some essential processes which has improved process control in the plant.
Sicherheitsanalysen zur systematischen Überprüfung von Verfahren und Anlagen — Methoden, Nutzen und Grenzen
Authors: Pilz Volker
Published: December 2004

Safety analyses for the systematic checking of chemical plant and processes–methods, benefits and limitations. Safety analyses, i. e. systematic procedures for the safety checking of chemical plant and processes, are useful for the completion and optimization of safety concepts. A literature survey of this topic reveals that hitherto procedures proposed can be divided into identifying and evaluating methods and can also be reduced to four basic working principles with a total of eight different methods. These eight main methods are presented using examples and are evaluated with regard to their appropriate use and the limitations which have to be kept in mind.
Bauarten von Kristallisatoren
Authors: Wöhlk Wolfgang , Hofmann Günter
Published: December 2004

Types of crystallizers. In the industrial application of single mass crystallization from solution clear aims exist with regard to crystallizate qualities. To fulfil these aims, one can choose between various types of crystallizers. Magma types, i.e. agitated tank crystallizer, forced circulation and draft tube (baffle) crystallizer, as well as classifying types with the well‐known Oslo‐crystallizer belong to the present state of the art. The rates of secondary nucleation decrease in the same sequence as that given above and the possibilities of influencing crystal size distributions increase, and coarser crystals are produceable.
Rationalisierung des Zeichnungswesens im Chemie‐Apparatebau
Authors: Blenke Heinz , Farys‐Kahle Beate , Von Meysenbug Carl‐Max Freiherr , Weimer Helmut
Published: December 2004

Rationalizing drawings for chemical apparatus. For small and medium‐sized manufacturers of apparatus, producing drawings may constitute a disproportionate waste of time and personnel, particularly when no new designs are involved but only modification or improvement of drawings supplied by the customer. One possibility for rationalizing drawing is to simplify the old‐fashioned approach by using symbols for frequently drawn or standard items, or by listing alphanumerically. This presumes a kind of systematization permitting determination of those symbols and their reasonable use, as well facilitating rationalization by means of data processing. There are different approaches to computer‐aided drawing (from computer controlled drawing‐board to interactive screens); here a CAD programme is presented which was especially developed for graphic presentation of chemical apparatus, and which can be used without learning a programming language.
Modellübertragung bei partieller Ähnlichkeit
Authors: Zlokarnik Marko
Published: December 2004

Scale‐up under conditions of partial similarity. When appropriate physical properties of the system are not available, it is impossible to accurately simulate the working conditions of an industrial plant in a laboratory‐scale experiment, and it then becomes necessary to resort to experiments under conditions of partial similarity. In these cases the laboratory‐scale experiments must be carried out in devices of various sizes and the results extrapolated to the industrial‐scale conditions. This expensive and inevitably unreliable procedure can occasionally be substituted by a systematic experimental approach based on dividing the process in question into individual parts which are then investigated separately (Examples 1 and 3), or by deliberately abandoning certain similarity criteria and checking the subsequent effects on the process as a whole (Example 2). In mixing technology, volume‐related mixing power is often taken as the scale‐up criterion, while in the design of bubble columns, the superficial velocity of the gas is taken as a basis. Both these cases are examples of scale‐up under conditions of partial similarity, and their validity is subjected to a critical examination (Examples 4 and 5).
Systematische Planung bei der Errichtung von Abgasreinigungs‐Anlagen
Authors: Rinn Gerhard
Published: December 2004

Systematic planning in the design of waste gas cleaning installations. Since the passing of the ordinance for largescale power stations and in view of the expected stiffening of the clean air regulations, many users of waste gas emitting plants are being forced to reduce these emissions. This paper describes a systematic and system‐oriented method of planning waste gas cleaning installations regarding a simple and general example. The method assures that the best waste gas cleaning installation is ultimately built.
Fortschritte auf dem Gebiet der Flüssig/Flüssig‐Extraktion
Authors: Blaß Eckhart , Goldmann Gerhard , Hirschmann Klemens , Mihailowitsch Pia , Pietzsch Wolfgang
Published: December 2004

Progress in liquid/liquid extraction. Liquid/liquid extraction continues to increase in importance. Classical areas of application, such as aromatic chemistry, hydrometallurgy, and reprocessing of spent nuclear fuels are being supplemented by new uses in biotechnology, in pharmaceutical production, and in water treatment. This upswing would be unthinkable without intensified R & D in chemistry and process engineering. Deeper knowledge of the physical chemistry of solvents permits purposeful choice of solvents for special separation tasks, advances in engineering elucidation of flow and mass transfer in proven and in newly designed extractors creates a basis for calculation or at least assessment criteria for the choice and operating behaviour of equipment. Yet much remains to be clarified. This article describes the current state of the art in the analysis of flow and mass transfer in countercurrent gravity feed columns with and without pulsation or agitator energy and in centrifugal extractors. A brief look at new designs demonstrates that scientific knowledge gave birth to the new ideas expressed therein.
Meßtechnik zur Charakterisierung von Gas/Flüssigkeits‐Reaktoren
Authors: Schügerl Karl , Lübbert Andreas , Korte Thomas , Diekmann JÜRgen
Published: December 2004

Measuring techniques for characterizing gas/liquid reactors. The article considers measuring techniques for the characterization of the phases in gas/liquid reactors. These include the velocity profile and turbulence in the continuous phase as well as holdup, size, and velocity of the dispersed phase. Also, methods for the determination of the specific interfacial area and the volumetric mass transfer coefficients are discussed. Measuring methods have made enormous advances in recent years. In spite of this, there is a lack of reliable methods, especially for use during reactions without disturbing the state of the reactor. It is suspected that probe technique will gradually fall into disuse and more and more attention will be focussed on contractless methods. This calls for further development of ultrasonic methods and methods relying on emission of light.
Systematik bei der Entwicklung von Katalysatoren für Oxidationsreaktionen
Authors: Schneider Peter , Emig Gerhard , Hofmann Hanns
Published: December 2004

Systematic approach to development of catalysts for oxidation reactions. The systematic catalyst development presented here for the example of a typical oxidation reaction shows that a systematic procedure is of value for a purposeful approach, and that statistically based planning and evaluation of experimental results represents an efficient tool. Physicochemical methods of study can provide important support for an understanding of catalytic action, with reaction‐engineering studies in various kinds of reactors necessarily playing a central role in catalyst development. Technical and economic assessment of a catalyst under development is already feasible in laboratory experiments and ultimately decides for or against its technical applicability. Understandably, the scale‐up of a production procedure developed in the laboratory to industrial quantities may also be beset with other problems which cannot be considered here.
Entwicklung von Siliciumcarbid‐Verbundwerkstoffen
Authors: Fitzer Erich , Fritz Werner , Gadow Rainer
Published: December 2004

Development of silicon carbide composites. This paper describes the production of fibre‐reinforced SiC composites applying the methods of chemical vapour impregnation (CVI), reaction bonding by liquid silicon impregnation (RB‐SiC), and impregnation with subsequent polymerisation and thermal decomposition of organosilicon compounds. The chemical and physical fundamentals of these processes are discussed. Composites of different fibre/matrix combinations are introduced; the most promising combinations can be selected from the experimental results presented.
Modultechnik — Zielsetzung, Aufbau, Konsequenzen und Erprobung
Authors: Mischke Joachim
Published: December 2004

Modular technique: objectives, layout, test facility. In spent fuel reprocessing plants the hot process cells cannot be entered by the personnel without intensive decontamination of the cells and the equipment. In the German reprocessing plant the FEMO technique (i. e. remote handling modular design) is used to achieve high plant availability and to reduce the radiation burden of the personal. The characteristics of the FEMO technique are two canyon cells in which the process equipment is installed in standardized racks arranged on both sides of each cell. The unit of process equipment and rack is designated as the module. This article reports the objectives of the modular technique, the resulting layout, and the test facility program to confirm this maintenance concept.
Reinraumtechnik
Authors: Gail Lothar
Published: December 2004

Clean room technology is essentially concerned with the control of particulate contamination. Sources of contamination are: air, work benches, personnel, machines, services. The control of airborne particles has already reached a high level. The cleanliness of process equipment can be further improved by the integration of laminar flow units. Cleanliness requirements and particle analysis meanwhile even cover liquidborne submicron particles. Classification systems for the cleanliness of liquids are in preparation. The contamination of powders results from different particle sources over the whole production process. The quality factor „particle control”︁ is in tended to prevent trouble and improve the economic efficiency and reliability of an increasing number of processes.
Aktuelle Probleme und Entwicklungen in der Biotechnologie
Authors: Rehm Hans‐Jürgen
Published: December 2004

Current problems and developments in biotechnology. Current developments in the field of biotechnology together with the actual problems are described with the aid of some examples. The new field of biotechnology has arisen especially from three methods, viz. gene technology, immobilized biocatalysts, and new developments in process technology. The influence of these methods on the development production techniques for ethanol, glycerol, HFCS, various secondary compounds, proteins, hormones, monoclonal antibodies, products from plant cells, but also on environmental biotechnology is described. These examples show that „classic”︁ biotechnology has greatly expanded by application of the methods presented. However, a comparison with the development of microprocessors is not yet possible.
Das Verhalten katalytischer Abgas‐Konverter aus reaktionstechnischer Sicht
Authors: Hoffmann Ulrich , Löwe Arno
Published: December 2004

Behaviour of catalytic exhaust converters from a reaction‐engineering standpoint. The technology of exhaust converters has been actively promoted and thoroughly documented in recent years. The present article is intended to demonstrate the contribution of chemical reaction engineering concepts and thought processes to this development. A recently published survey [1] emphasized the relevant general principles of micro‐ and macrokinetics, while the present paper discusses the integral behaviour of exhaust converters with the aid of selected examples.
Homogenisieren von Schüttgütern in Mischsilos
Authors: Wilms Harald
Published: December 2004

Homogenization of bulk solids in blending silos. Blending silos are used for blending and homogenization of large quantities of bulk solids. Depending on how the energy is introduced, we distinguish between pneumatic, mechanical, and gravity flow blenders. The different blending principles are described and the suitability of the blending systems for certain types of bulk solids is explained. Fluidized bed blenders are suitable for homogenization of free flowing fine powders. Gravity flow blenders are used for blending of granular bulk solids. Homogenization of cohesive powders is accomplished in mechanical blending silos. It is necessary for selection of a suitable homogenization system to know the fluidization behaviour and the flow properties of the respective bulk solids. These properties can be determined in laboratory tests.
Neues Verfahren zur Methanol‐ und Ammoniak‐Synthese. Der Gas/Feststoff/Feststoff‐Rieselströmungsreaktor – ein neuer Reaktortyp zur Führung chemischer Gleichgewichtsprozesse
Authors: Westerterp K. Roel , Kuczynski Michal
Published: December 2004

New process for the production of methanol and ammonia. The gas/solids/solids thrickle flow reactor – a new kind of reactor for chemical equilibrium processes. A new process for the production of ammonia or methanol has been developed in the high pressure laboratory of Twente Technical University. The reactants can be made to react completely in a single reactor pass, thus avoiding expensive recirculation. Complete reaction without recirculation is accomplished by a combination of two reversible processes: a chemical reaction and a selective adsorption of the reaction product on a solid in constant flow. On introduction of an inert‐gas free stoichiometric mixture of reactants into the reactor, the exhaust gas outlet can be closed. If there is an excess of one of the reactants or of inert gas, it can leave from the top of the reactor. Such a process has been accomplished in a new gas/solids/solids trickle flow reactor in which a granulated adsorbent „rains”︁ through a fixed bed of catalyst. The present article describes the use of this kind of reactor for methanol synthesis. Considerable savings in production costs are expected relative to the modern Lurgi low pressure process. A pilot plant is to be built to characterize and evaluate the new process. Royal Dutch Shell has registered a patent application.
Stofftrennung mit überkritischen Gasen (Gasextraktion)
Authors: Brunner Gerd
Published: December 2004

Mass separation with supercritical gases (gas extraction). The solvent power of dense gases is considered with ongoing interest for use in technical processes. A great number of gaseous solvents are available, especially if solvent mixtures are included. These solvents can be used in one‐stage or multiple‐stage processes, running batchwise or continuously in countercurrent process. Design the equipment and simulation of the process requires correlation of the underlying phase equilibria. Remarkable progress has been achieved in this field. In some cases data on mass transfer have also been published. Several companies supply turnkey plants or specialized equipment from laboratory to pilot scale. Commercial plants are used extracting natural products and mineral oil residue processing.
Photophysikalische Meßverfahren zur Untersuchung von Gas/Flüssig‐Reaktoren
Authors: Wild Gabriel , André Jean‐Claude , Midoux Noël
Published: December 2004

Photophysical measuring techniques for the study of gas/liquid reactors. After a brief account of the fundamentals of photophysics, the authors describe various photophysical measuring procedures, with reference to available instrumentation, including prices. The measuring methods permit contactless and intertialess determination of various quantities in very small volumes (temperature, viscosity, concentration, pH, orientation of molecules, etc.). The authors examine which methods are available for the study of gas/liquid reactors. The most promising studies seem to involve the heat effects accompanying absorption with chemical reaction, study of interfacial effects (slowing mass transfer by accumulation of surface‐active impurities, Marangoni effect), and the observation of complex reaction systems. Photophysical measuring techniques can also be used for measurements in industrial reactors; some of the known applications are described.
Sicherheitstechnik bei der Handhabung von Wasserstoff
Authors: Baumgärtner Klaus , Ewald Rolf
Published: December 2004

Safety engineering in the handling of hydrogen. After a survey of the handling of hydrogen as a gaseous or liquid industrial gas, possible safety risks are discussed in the light of its properties, and primary, secondary, and tertiary safety measures are deduced therefrom. The most important German regulations for stationary and mobile hydrogen installations are indicated. A comparison shows that hydrogen, which was introduced into industry decades ago, is no more dangerous than other inflammable gases and liquids freely available even to the public.
Methoden zur Immobilisierung von Bodenkontaminationen
Authors: Stammler Manfred , Hass Hans J.
Published: December 2004

Methods of immobilizing soil contamination. A number of remedial measures can bei applied to contain or immobilize contaminants which threat to pollute groundwater, soil or air. Some are still conceptional in character, others are in practical use. So far, bentonite/cement‐based slurry walls have often been constructed to regulate the groundwater flow in contaminated areas. In general, clay layers are used as bottom seal whenever available. Investigations, however, have shown that conventional and many natural materials do not exhibit the resistance to aggressive leachates which is necessary to retain the contamination over extended periods of time. In the proposed concept a partial or complete encapsulation of the contamination is recommended using barriers resistent to aggressive leachates, thus containing the contamination. This can be achieved by new silica gel containing materials and in some cases by suitable geotextiles. Extensive tests of such materials are presently under way at various abandoned waste sites in the F. R. Germany. Remedial action can then be planned and executed to decontaminate the site in ample time and without the risk of further contamination. New results are reported obtained during a one year test period with water glass of low alkalinity and high SiO2/Na2O ratio. Their resistance to leachates, low syneresis, and high hardness was accomplished by the two‐component system Dynagrout PPN, developed by Dynamit Nobel.
Energieverfahrenstechnik
Authors: Mayinger Franz
Published: December 2004

Energy process engineering. In the course of an energy transformation process engineering problems occur in connection with: the energy supply in the form of fossil, nuclear, or alternative sources; the operation of energy converters, such as power plant, coal processing plant, or equipment for hydrogen generation; and in disposal of waste and pollutant materials produced in these transformation plant. In analogy with the definition of the task of process engineering – i. e. transformation of materials on an industrial scale – the purpose of energy process engineering can be delineated as the treatment of materials which find application or occur in energy conversion, whether as energy sources, as intermediates, or as undesired waste or ballast materials. After surveying the possible variety of the tasks of energy process engineering, the article briefly discusses the present state of the art with the aid of selected examples. An attempt is then made to introduce some kind of system into this wide‐ranging material. In view of current activities, it appears appropriate to first concentrate on the treatment of residual materials – waste and ballast – in various methods of energy conversion.
Wake‐Phänomene hinter festen und fluiden Partikeln
Authors: Wasowski Tomasz , Blaß Eckhart
Published: December 2004

Wake phenomena behind solid and fluid particles. While detailed information is available about the nature and the phenomology of the wake, there is a distinct lack of practically useful and quantitative information about the size of the wake behind single fluid particles and in a swarm thereof. Many studies have been performed on the wake behind individual particles, yet the results are not only fragmentary, i. e. of little relevance for the operating regime of bubble columns, but also beset with surprisingly large discrepancies. These considerable differences are of a systematic nature and due partly to insufficient elimination of surfactant effects, partly to different boundary effects of the experimental equipment, and partly to differing measuring techniques. Experimental results for the wake in swarms of droplets and bubbles in the relevant operating regime are still completely lacking.