bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maßstabsvergrößerung chemischer Reaktionsapparate
Authors: Riekert Lothar 
Published: December 2004

AbstractScale‐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

AbstractProduction 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

AbstractElectrodialysis – 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

AbstractHandling 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

AbstractEconomic 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

AbstractCauses 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

AbstractHigh 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

AbstractSafety 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

AbstractTypes 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

AbstractRationalizing 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

AbstractScale‐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

AbstractSystematic 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

AbstractProgress 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

AbstractMeasuring 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

AbstractSystematic 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

AbstractDevelopment 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

AbstractModular 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

AbstractClean 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

AbstractCurrent 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

AbstractBehaviour 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

AbstractHomogenization 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

AbstractNew 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

AbstractMass 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

AbstractPhotophysical 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.