bluuebunny/crossref_metadata_2025_split huggingface dataset:
Das Klassieren disperser Feststoffe in gasförmigen Medien
Authors: Leschonski Kurt 
Published: December 2004

AbstractEs wird eine zusammenfassende Darstellung über die bisherige technische Entwicklung der Windsichtung, ihre Anwendung im Labor und Betrieb, die auftretende Problematik und die Möglichkeiten der theoretischen Vorausberechnung gegeben. Die Klassierung disperser Feststoffe in gasförmigen Medien, die im Trenngrenzenbereich von etwa 1 bis 100 μm und bei Massendurchsätzen von wenigen Gramm bis zu einigen 100 t/h durchgeführt wird, besitzt eine erhebliche technische Bedeutung und ein breites Feld der Anwendung. Allen Verfahren gemeinsam ist die unterschiedliche Bewegung verschieden großer Partikel in Strömungsfeldern, die zur Trennung des Aufgabegutes in wenigstens zwei Fraktionen führt. Neben ebenen Strömungsfeldern werden rotationssymmetrische ebene oder drallbehaftete Strömungen verwendet, die sich entsprechend der hauptsächlichen Bewegungsrichtung des Grobgutes in Gegenstrom‐ und Querstromanordnungen unterteilen lassen.
Analysensysteme für Wasser und Abwasser
Authors: Hilgers Wilhelm 
Published: December 2004

AbstractWasseranalysensysteme werden dort eingesetzt, wo mehrere Meßgrößen in der gleichen Wasserprobe erfaßt werden sollen. Man unterscheidet dabei das Eintauchverfahren, bei welchem die Meßfühler unmittelbar in das Gewässer oder die Kanalisation eingetaucht werden, und das Durchflußverfahren, bei welchem aus dem Gewässer oder der Kanalisation mit Hilfe einer Förderpumpe eine Probe entnommen und dem Gebersystem im Durchlauf zugeführt wird. Der kontinuierliche Betrieb derartiger Wasseranalysensysteme wird durch die mehr oder weniger starke Verschmutzung der Wasserproben gefährdet und erfordert besondere Maßnahmen, um die Funktionssicherheit und Meßgenauigkeit über längere Zeiträume aufrecht zu erhalten. Durch eine automatische Eichkontrolle kann die Funktion und die Meßgenauigkeit des Systems kontrolliert werden. Gegebenenfalls werden Steuergeräte und Grenzwertmelder sowie in bestimmten Fällen auch Einrichtungen zur Datenfernübertragung und zur Rechneradaption vorgesehen.
Zur Endlagerung radioaktiver Abfälle
Authors: Proske R. 
Published: December 2004

AbstractDisposal of Radioactive Wastes. In this paper the problems and the status of the disposal of radioactive wastes in geologic formations are discussed, particular attention being paid to the suitability of salt formations. Furthermore, experiments on the disposal of radioactive wastes carried out in the former salt mine Asse are also described. After considering the concept of the future repository in the Waste Management Center the safety of such geological and mining disposal systems is examined and alternatives are discussed.
Meßmethoden konvektiver Stoffübertragung
Authors: Kottke Volker , Blenke Heinz 
Published: December 2004

AbstractMethods of measuring convective mass transfer. The principal methods of measuring convective transfer of momentum, heat, and mass are surveyed on the basis of the three‐fold analogy existing between the transfer of momentum, heat, and mass. The most simple and most sensitive method is the mass transfer technique based on the principle of absorption with chemical reaction and coupled colour reaction. It is shown by selected examples that this measuring technique is already developed to the point where it serves adequately for the solution of most complex problems met with in practice. It is distinguished by its high accuracy of measurement, simple application, high local resolution, and its utilizability both for developable as well as for undevelopable surfaces. By way of the local mass transfer observable as colour‐intensity distribution it also affords a simple and illustrative means of making flow processes on solid surfaces visible. The quantitative evaluation is accomplished by reflectance photometry; quantitative image processing methods are available for complex distributions. In addition, it is shown that the mass transfer technique is also suitable for practical utilization as a method for measuring turbulence. The measuring principle is based on the extremely high dependence of the length of transitional separation bubbles in the nose section of flat plates of finite thickness in longitudinal flow on the turbulence intensity.
Vermischungseffekte in Flüssig/Flüssig‐Extraktionskolonnen
Authors: Marr Rolf , Moser Franz 
Published: December 2004

AbstractAxial mixing in liquid/liquid countercurrent extractors. Methods are considered for the determination of longitudinal mixing in many countercurrent extractors. It is found that only the single phase mixing of the continuous phase can be accurately determined; with certain reservations this also applies to the disperse phase. In the case of RDC and ARD in particular, correlations are available which permit calculation of Bodenstein numbers for both phases. Such scale‐up calculations are not recommended for many extractors. It is very important to establish adequate correlations for calculation of mixing of the disperse phase in order to obtain exact dispersion heights in connection with those of the continuous phase.
Beschreibung der Bewegungsvorgänge diskret‐disperser Systeme durch das Diffusionsmodell
Authors: Ebert Fritz 
Published: December 2004

AbstractDescription of the motion of collectives of particles by the diffusion model. The paper deals with the problems involved in the use of the diffusion model, initially established for molecular systems, to the motion of collectives of particles. Under the following conditions the diffusion model provides a reasonable description of the motion of particles suspended in turbulent flow: The collective of particles enclosed in a volume small compared with the characteristic length of the flow configuration must be sufficiently large for interpretation of the particle concentration and the transport coefficients as field variables. The time for a statistically mean step of the particle motion, given by the Lagrange integral scale, must be very small compared with the mean residence time in the flow configuration. Aerosol deposition and air classification of finely dispersed solid particles are treated as practical examples.
Feste Ionenleiter, Grundlagen und Übersicht
Authors: Rickert Hans 
Published: December 2004

AbstractSolid ionic conductors – a review. The conductivity of solid electrolytes, like that of liquid electrolytes, is determined by the concentration and mobility of the mobile ions. There are solid electrolytes in which all particles of one particular type are mobile and the mobility of these ions is as great as that in molten salts or liquid electrolyte solutions. A partial lattice of the otherwise solid crystal is then in a quasimolten state. The conductivity itself now has values as in salt melts or concentrated liquid electrolyte solutions. The solid electrolyte has then reached the maximum value for the ionic partial conductivity. Important solid electrolytes with high ionic conductivities are discussed.
Einführung in die Transportvorgänge in konzentrierten wäßrigen Elektrolytlösungen und Salzschmelzen
Authors: Richter Joachim 
Published: December 2004

AbstractIntroduction to transport phenomena in concentrated aqueous electrolyte solutions and molten salt mixtures. Up to this day there is no general theory of liquids. Since water‐free molten salt mixtures are simpler in their structure than concentrated aqueous electrolyte solutions, it would be reasonable first to develop a theory for molten salts and then to apply this to aqueous electrolyte solutions by approximation. Such a theory does not yet exist. In this paper the system water + salt is therefore considered in the concentration range between pure water and pure salt in the liquid state. The phenomenological coefficients and friction coefficients of the different species of the system calculated from transport data are characteristic parameters for the entire concentration range which will probably offer possibilities for the analysis of transport phenomena, in close relation with the structure of the water + salt mixture. Common and essentially different properties, such as reference system and condition of electric neutrality, are discussed for concentrated aqueous electrolyte solutions and molten salt mixtures. The investigation of transport numbers from concentration cells with transference and the determination of the interdiffusion coefficients are illustrated for the system H2O + CaCl2 (highly concentrated electrolyte solution) and LiNO3 + AgNO3 (molten salt mixture). The phenomenological coefficients and the friction coefficients are calculated from the measured transport data.
Zukunftssichere und umweltneutrale Beseitigung von Industrieabfällen
Authors: Heitmann Aloys 
Published: December 2004

AbstractLow environmental‐impact disposal of solid, liquid and semisolid industrial residues. In many production plants, waste residues are formed which must be treated before their disposal so as to safeguard against environmental pollution. Industrial methods for the treatment and disposal of residues are so multifarious that each disposal problem requires careful consideration so as to ensure selection of the most suitable method, both from the ecological and economical point of view. Dumping grounds cannot accommodate all waste materials without endangering or disturbing the environment. For incineration, proven methods are available which can be modified to suit the particular waste problem at hand. After a suitable pretreatment every effort must be made to achieve a waste free from organic materials, an optimum utilization of heat and a flue gas purification without inadmissible loading of waste gases and waters. In recent years there has been a considerable increase in research and development activities in the area of thermal treatment of solid, liquid and semi‐solid wastes. Worth mentioning are the high‐temperature methods giving favourable emission values and methods for degasification and gasification directed at the recovery of important raw materials. Plants based on these principles are currently being operated on the pilot scale.
Tendenzen beim Bau von Anlagen für die Düngemittelindustrie
Authors: Wagener Dietrich , Laue Karl Heinrich 
Published: December 2004

AbstractTrends in the construction of plant for the fertilizer industry. As shown by the example of an ammonium nitrate plant, savings in plant operation can be achieved and environmental pollution decreased by process modification. If the neutralizing reactor is operated at elevated pressure the steam evolved can be utilized as process steam. On neutralization at normal pressure, polluted steam escapes to the atmosphere and is wasted.
Exergetische Bewertung des Einsatzes von Wärmepumpen (Brüdenverdichtern) in Anlagen der Chemischen Industrie
Authors: Stockburger Dieter , Bartmann Lutz 
Published: December 2004

AbstractEnergy evaluation of incorporating heat pumps (vapour compressors) in chemical plant. Both the prevailing tendency of steeper price‐hikes for fuel than for equipment and the imminent shortage of conventional fuels are stipulating measures aimed at decreasing energy consumption. The energy requirements of different variants of a particular process can be compared by using an efficiency based on availability, if the lowest process temperature is used instead of the commonly applied ambient temperature. The method is explained with reference to two examples.
Einfluß thermodynamischer und fluiddynamischer Vorgänge auf die Notentspannung chemischer Reaktoren
Authors: Gärtner Dieter , Giesbrecht Hartmut , Leuckel Wolfgang 
Published: December 2004

AbstractInfluence of thermodynamic and fluid dynamic mechanisms upon the emergency pressure relief of chemical reactors. The cross‐sectional areas of pressure relief devices for storage tanks and reactor vessels containing liquids under vapour pressure, which might undergo dangerous heating up, have so far been estimated on the basis of physically questionable procedures. This report analyses the pressure relief process using several extreme assumptions with regard to momentum and heat transfer in two phase flow. A conservative method of estimation is found under the assumptions of homogeneous flow and vapour‐liquid equilibrium. Using this procedure, a parametric study of the pressure relief process for a runaway polymerisation reaction has been carried out. Finally, recommendations are given concerning design of the vent line and control of the atmospheric dispersion of the relief stream via the jet exit momentum.
Gewässerschutz in der BASF AG, Ludwigshafen
Authors: Engelhardt Hubert , Haltrich Walter G. 
Published: December 2004

AbstractWaste water purification at BASF, Ludwigshafen/Rh. The manifold problems encountered in the field of waste water treatment in the chemical industry are considered, together with the tasks involved, possible solutions, and costs incurred, for the example of BASF AG in Ludwigshafen. This example is particularly interesting because it shows how the waste water problems of a chemical factory that has been in existence for over a centurvey could be solved in the course of a ten‐year plan. Twenty years after the inception of this plan, costs and success can now be quantified.
Auslegung von Granulierteller und Granuliertrommel
Authors: Sommer Karl , Herrmann Walter 
Published: December 2004

AbstractDisign of granulating plates and granulating drums. Equations relating mechanical and geometrical parameters have been derived for use in calculating the power requirements of granulating plates and granulating drums. An attempt is made to maintain the same product properties, especially the porosity and size of the agglomerates, on scale‐up of the granulating equipment. This condition considerably limits the possible operational parameters. In order to define the operating conditions on scaling‐up from model experiments, their influences are described in terms of theoretical models and empirical results. The utility of the expressions derived is illustrated using the design of a granulation plate as example.
Großtechnische Herstellung von Reinstsilicium
Authors: Silbernagel Heinz 
Published: December 2004

AbstractLarge scale production of hyperpure silicon. Silicon still remains one of the most important elements in use in semiconductor technology. Worldwide production of silicon amounts to more than 1000 t/year. Its use in semiconductor components calls for special requirements, such as extreme purity in the ppb‐range, absolutely perfect crystals, and narrow dimensional tolerances and special surface properties of fabricated silicon slices. Reaction of 95% pure metallurgical grade silicon and hydrochloric acid results in trichlorosilane, which is then purified by distillation. This is subsequently subjected to a reductive cracking process in order to produce hyperpure polycrystalline silicon. Monocrystalline silicon rods are then manufactured by one of two crystal growing methods, either by crucible pulling (Czochralski) or by float zoning. The single crystals thus obtained are then sliced by diamond cutting machines. Depending on their final use the slices are then processed by lapping, polishing, epitaxy, etc.
Über die Herstellung von Cellulasen und die enzymatische Spaltung von Cellulose
Authors: Linko Pekka 
Published: December 2004

AbstractProduction of cellulases and enzymatic cleavage of cellulose. Recent work on production of cellulolytic enzymes and on enzymatic degradation of cellulose is described. For optimum enzyme production by Trichoderma reesei under carefully balanced growth conditions, cellulose levels as high as 2% may be employed. Nitrogen deficit may be economically avoided by adding organic nitrogen in the form of distiller's spent grain and dried ground T. reesei cell mass. Semicontinuous production has been shown to offer further special advantages. Cellulase activity may be directly monitored automatically in a computer‐controlled pilot fermentation system. Xylitol and furfural process wastes have been shown to be suitable substrates for cellulase, requiring little or no costly pretreatment. The rate of cellulose hydrolysis is considerably increased by combined use of T. reesei and cellobiase active microorganisms such as Aspergillus phoenicia.
Methodisches Konstruieren einer Anlage zur Herstellung von Atemkalk
Authors: Rodenacker Wolf G. , Schäfer Jürgen 
Published: December 2004

AbstractMethodical design of a plant for the production of CaO for use in breathing equipment. The methodology of design nowadays taught at all technical universities can also be profitably applied to chemical engineering. Methodical examination of the production process for CaO used as CO2 absorber in respiratory equipment leads to a considerable improvement in product quality and to more economical production.
Hydrodynamisches Verhalten und Stoffübergang an Siebböden im Sprudel‐ und Sprühbereich
Authors: Sawistowski Henry 
Published: December 2004

AbstractHydrodynamic and mass transfer behaviour of sieve plates in the spray and bubble regimes. An attempt is made to set up idealized hydrodynamic models for the bubble and spray regimes on sieve plates and thus to provide a basis for calculation of mass transfer and concentration ratio. Comparison of the dependence of plate efficiency in the two regimes on various parameters indicates the importance of being able to determine a practical phase transition point. This was defined on the basis of the contribution of the bubbles and droplets to the overall interfacial area and compared with the transition points of other authors. The operation of columns in the spray regime, formerly regarded as undesirable, now possesses considerable industrial significance. This was mentioned by Zuiderweg [29] in his Underwood lecture of 1973. Since that time larger perforations and higher gas velocities have been employed. There has consequently been a significant shift of sieve plate behaviour from the bubble to the spray regime. It is estimated that almost 80% of all industrial sieve plate columns now operate in the spray regime and should be specifically designed for such operation.
Meteorologische Probleme bei der Bestimmung von Schornstein‐Mindesthöhen
Authors: Manier Gerhard 
Published: December 2004

AbstractMeteorological problems in determining minimum stack height. In the Federal Republic of Germany the minimum stack height must be determined with the aid of the “TA Luft” code. The method of determination has been developed with a number of simplifications concerning constancy and homogeneity of emission data, meteorological parameters, and topographical structure. The influences of these simplifications are discussed, and improved methods of determining necessary stack heights are described.
Pyrolytische Rohstoff‐Rückgewinnung aus Sonderabfällen
Authors: Collin Gerd , Grigoleit Georg , Bracker Gerd‐Peter 
Published: December 2004

AbstractPyrolytic recovery of raw materials from special wastes. The pyrolytic techniques developed especially for producing smelting coke from coal and in petroleum refining can be applied to the thermal decomposition of waste materials having a high organic content. Fluidized bed reactors and rotary kilns are particularly suitable as universally applicable pyrolysis units for continuous operation. Highly aromatic pyrolysis oils for use as chemical raw material, heating gases for the autothermic operation of the pyrolysis unit, and carbon and solids containing nonferrous metals are obtained from plastics waste, used tires, old cable, shredder wastes, and acid resins at reactor temperatures of about 700°C. Largescale applicability and economics of the process have yet to be proved.
Eignung von kontinuierlich durchströmten Mischern zum Homogenisieren
Authors: Henzler H. J. 
Published: December 2004

AbstractSuitability of continuous flow mixers for homogenization. The homogenizing characteristics, calculation of power consumption, and the scope of continuous flow mixers are reported. An attempt is made to summarize the present state of knowledge in this area. Some experimental results are presented which have been obtained in the homogenization of gases or liquids in pipes and containers in which mixing was achieved by jets, built in flow‐directing fittings, stirrers or a combination of these. The investigations extend from the laminar to the turbulent range of flow. A comparison of energy requirements for the various apparatus affords important data for the choice and design of continuous flow mixers.
Fortschritte bei der Modellierung von Festbettreaktoren
Authors: Hofmann Hanns 
Published: December 2004

AbstractProgress in the modeling of fixed bed reactors. Recent work on the modeling of catalytic fixed bed reactors have led to more realistic mathematical models and to a better understanding of problems connected with modeling. Nowadays standard routine computer programs are available for use in the design (and analysis) of catalytic fixed bed reactors for very complex reaction systems. The influence of bed structure on transport parameters was illustrated by experimental determination of axial and radial concentration and temperature distribution. Moreover the problem of multicomponent diffusion coupled with complex reactions in porous catalysts has been solved and can be included in the reactor model. However, the practical application of possible reactor models is limited by the availability of transport parameters for fixed beds.
Blasensäulen‐Reaktoren mit suspendiertem Feststoff: Grundlagen — Auslegung — Anwendungen
Authors: Hammer Hans 
Published: December 2004

AbstractBubble column reactors with suspended solids – fundamentals, design, and uses. The article describes the determination of hydrodynamic functions such as bubble size frequency distributions, relative gas contents, Sauter diameters, and specific interfacial areas in various liquids and in binary and ternary mixtures of organic liquids. The article also covers the local variation of these quantities as a result of coalescence, and axial and radial mixing coefficients. Formal Reynolds' analogies could be set up for heat and mass transfer – both across the gas/liquid interface and at the solid wall/bubble column interface without or with suspended solids. A brief survey of industrial processes in three‐phase reactors, especially in petrochemistry and biotechnology, closes with an indication of the expected growth in importance of such reactors as a consequence of the present trend towards heterogenization in homogeneous catalysis.
Meßtechniken zur Bestimmung der Eigenschaften von Blasen in Blasensäulen
Authors: Buchholz Rainer , Zakrzewski Wolfgang , Schügerl Karl 
Published: December 2004

AbstractTechniques for determining the properties of bubbles in bubble columns. Three different methods for the determination of bubble size parameters namely (i) flash‐photography followed by image analysis, (ii) use of a conductivity probe with two electrodes and electronic processing of the signals, and (iii) the electro‐optical probe with the same signal processing as the conductivity probe are compared and contrasted from the viewpoint of their optimal use, their accuracy, and their scope of application.