bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bestimmung der Schalleistung von Zentrifugen über Schallintensitätsmessungen
Authors: Stelter Peter , Harms Andreas 
Published: December 2004

AbstractThe sound pressure level measured at a distance of one meter is frequently used to assess the sound emission of a machine. The sound pressure level depends on the measuring distance, the directivity pattern, if any, of the machine and on the sound‐absorbing properties of the place of installation. Because it is a local field parameter it is not very suitable for ascertaining the sound emission of a machine. In contrast to, the sound power level is far more suitable because the influence mentioned earlier can be corrected and the value is reproducible for any random test condition. Generally, it is calculated from the results of sound pressure level measurements by application of the standardised enveloping surface method. Concerning sound intensity measurements a special probe allows ascertainment of the sound intensities directly on the enveloping surface. Despite an initially elaborate measuring technology, this method is in fact often faster and more exact than the enveloping surface method because it does not require subsequent correction to determine the sound power level. The benefits and drawbacks of sound pressure and sound intensity measurements are compared with each other on the basis of measurements on centrifuges directly related to practical operation.
Entwicklungstendenzen bei der Partikelabtrennung aus Gasen mit filternden Abscheidern
Authors: Schmidt Eberhard 
Published: December 2004

AbstractCleanable surface filters are used as highly efficient separation devices for removing particles from gases in three major areas of application, viz. reduction of emissions, product recovery, and process gas purification. In order to utilize their excellent separating properties in processes where unfavorable operating conditions mean that competing kinds of separators have hitherto been used, filtering separators are undergoing constant development. This paper presents and discusses future‐oriented developments from current work and completed plant in the three areas of ‘modeling/computer simulation’, ‘filter medium development’, and ‘crude gas conditioning’.
Praxisbezogenes Vorgehen bei der Auslegung von Sicherheitsventilen und deren Abblaseleitungen für die Durchstroömung mit Dampf/Flüssigkeits‐Gemischen – Teil 2
Authors: Schmidt Jürgen , Westphal Frank 
Published: December 2004

AbstractThe design of an integral safety valveblow‐off pipe system embraces the following essential steps: 1. An incident scenario must first be defined. All reasonable deviations from proper operation of plant must be considered. 2. The flow state at the entry to the safety valve must then be ascertained (one‐phase or binary flow); and 3. the minimal mass flow from the plant component to be protected must be calculated. Independently thereof, it is necessary 4. to determine the mass flow density in the blow‐off pipe system; it is usually related to the cross‐sectional area of the valve seat. The ratio of the two quantities gives the minimum necessary blow‐off cross‐sectional area. 5. In the final step, the pressure drop in the feed line and the counter‐pressure at the valve exit must be examined in order to assure reliable functioning of the valve also in conjunction with the pipe system. Steps 1. to 3. were considered in Part 1, and steps 4. and 5. are described herein. Appropriate recommendations and the necessary equations are given for each step. The main emphasis is placed on applicability of the calculations.
Gasinduziertes Einmischen von Reaktionsstoppern in Behälter mit niedrigviskosen Flüssigkeiten
Authors: Schimetzek Ralf , Pfleger Dirk , Ulonska Armin 
Published: December 2004

AbstractThese studies consist of experiments, physical modelling, and numerical simulations concerning gas‐induced injection and mixing of reaction inhibitors in vessels containing low viscosity liquids. The mixing times required to achieve a final mixing quality of 95% were determined by means of a decolorization technique and a probe method (conductivity probes). The mixing time decreases with increasing gas flow rate, liquid level, eccentricity of the gas injection point, and with decreasing liquid viscosity. Based on fundamental physical principles, analytical models were developed which can be used to estimate, with an average precision of ± 13 %, the mixing times measured on three different scales. The results of scale‐up were additionally confirmed via numerical simulations. The results of these studies show that gas‐induced mixing of reaction inhibitor solutions can represent a reliable safety system for preventing exothermal runaway reactions. Moreover, direct injection of gas may also be used for admixing additives during normal operation of reactors and storage tanks.
Messung der dynamischen Grenzflächen‐spannung im System wäßrige Tensidlösung/organisches Lösungsmittel
Authors: Miller Reinhard , Ferrari Michele , Ravera Francesca , Liggieri Libero , Zholob Sergej A. , Fainerman Valentin B. , Neumann A. Wilhelm 
Published: December 2004

AbstractDynamic interfacial tensions provide insight into the mechanism of surfactant adsorption at and transport across an interface. As an example, the adsorption kinetics and the distribution of a surfactant (alkyl dimethyl phosphine oxide with an alkyl chain length of 13) was studied at the water/hexane interface. The drop shape method used yields dynamic interfacial tensions that pass through a minimum under certain conditions. Model calculations show that depth, width and location of the minimum and the equilibrium adsorption state depend on several parameters: the diffusion coefficients of the surfactant in the two liquids, the distribution coefficient between the phases, the liquids volume ratio, and the total surfactant concentration in the system. One can conclude that surfactants are often soluble in both liquid phases, and transfer across the interface between them has to be considered. If a surfactant is to be optimized in a liquid‐liquid system to achieve maximum efficiency of a technological process, the surfactant distribution coefficient plays a significant role.
Chemisches Recycling von Kunststoffen
Authors: Sasse Frank , Emig Gerhard 
Published: December 2004

AbstractOn completion of the first life cycle of plastics various recycling processes are available for further utilization of these evaluable materials. The choice of process will depend upon the materials to be recycled. In chemical recycling polymers are degraded to basic chemical substances which can be reused in the petrochemical industry. This route plays a key role for soiled waste plastics or waste plastics which could not hitherto be recycled. The pyrolysis of acrylic polymers provides a good basis for comparing a fluidized bed reactor and a tubular reactor with regard to reactor modelling. The tubular reactor with internal mass transport is a simplified model for a rotary kiln. Parameters relevant for reactor design and scale‐up are presented.
CAE‐Systeme für die Prozeßleittechnik
Authors: Ahrens Wolfgang 
Published: December 2004

AbstractCAE systems for the workings of chemical engineering plant have reached a high level of functionality and system architecture. This also applies to process control systems. What is now needed is the integration of the different systems in order to avoid unnecessary duplication of effort, data inconsistency, and time wastage. Fortunately, there are various approaches permitting such integration. Starting from the underlying system architecture this paper therefore presents a variety of integration concepts. Some of these are propriety solutions because they are based on various manufacturers' products. However, STEP and CORBA also involve standards‐based technologies. The time required for their realisation is better estimated in years.
Qualitätsmanagement bei der Herstellung von Chemieapparaten aus Sonderwerkstoffen
Authors: Renner Michael , Lorsbach Birgit , Schumacher Kurt 
Published: December 2004

AbstractQuality Management during the Fabrication of Chemical Equipment Made of Special Materials Optimizing a material's resistance to corrosion by the addition of alloying elements up to their solubility limits will make it increasingly difficult to use these frequently unstable alloys for the manufacture of chemical plant. The requirements these materials have to meet in the manufacture of chemical plant in terms of manufacturing technology and quality management, are becoming increasingly stringent. The current situation, for example in the manufacture of domed heads of pressure vessels, forgings, heat exchangers, and filter screens with a high specific surface area as a constituent part of stirred suction filters using advanced metallic materials, is not very satisfactory. Results of fabrication tests necessary for pressure vessel manufacture as well as in‐service failures frequently demonstrate insufficient expertise of workshops dealing with high‐alloy stainless steels and nickel‐based materials. That the in‐service failure of compoents clearly leads to considerable costs due to maintenance, delays in supply, and production downtimes. The economic consequences can be substantial. The aim of this paper is to highlight sensitive areas by demonstrating the impact of unintentional and unnoticed fabrication‐related changes in welding parameters and to provide information on easily applicable methods of monitoring techniques.
Feststoff‐Bioreaktoren – Teil 1: Stationäre Anlagen
Authors: Vollbrecht Dietmar 
Published: December 2004

AbstractSolid State Fermentation‐Bioreactors – Part 1: Stationary Types. After World War II, solid state fermentations (SSF) in automated facilities developed rapidly in East Asia countries, especially Japan, to achieve a present annual market volume of about $ eight billion. In contrast, SSF, after having been introduced in Western countries at the onset of this century, became almost completely neglected. The comparative ease of running SSF bioreactors and in particular their low processing costs and considerably higher yields in comparison with submerged fermentation (STF) suggest that this technology might have great economic importance in producing food and pharmaceutically valuable substances such as antibiotics, anti‐carcinogenic substances, antioxidants, flavors, fragrances, health foods, hypocholesterinemic agents, pigments, starter cultures, protein‐enriched feed, thrombolytic enzymes, vasoactive agents, vitamins etc.
Einsatz von Pervaporation‐Bioreaktor‐Hybridprozessen in der Biotechnologie
Authors: Lipnizki Frank , Hausmanns Stephan , Laufenberg Günther , Field Robert , Kunz Benno 
Published: December 2004

AbstractUse of Pervaporation/Bioreactor Hybrid Processes in Biotechnology Pervaporation is a membrane separation process with considerable innovative possibilities in the area of biotechnology. Above all, the combination of bioreactor and pervaporation has potential in the longer term as an alternative to conventional batch processes. This article considers the state of the art of pervaporation/bioreactor hybrid processes. The possible applications of such hybrid processes are discussed and compared with conventional processes. It becomes apparent that the use of pervaporation/bioreactor hybrid processes can avoid product inhibition and greatly enhance the productivity of biotechnological processes.
Nanofiltrationsmembranen für Trennprobleme in organischen Lösungen
Authors: Schmidt Matthias , Mirza Sohail , Schubert Rolf , Rödicker Em. Herbert , Kattanek Siegfried , Malisz Jaček 
Published: December 2004

AbstractNanofiltration Membranes for Separation Problems in Organic Solutions.Nanofiltration based on rejection and flux features intermediate between those ultrafiltration and reverse osmosis is one of the technically and scientifically interesting membrane processes with a great future. Moreover, most commercial available nanofiltration membranes are only suitable for separation processes in aqueous solutions. A small number of composite membranes with a highly cross‐linked selective layer show a technically interesting resistance towards organic solvents, such as ketones, esters, ethers or alcohols. The present article describes such nanofiltration membranes used for separation of low molecular weight chemical compounds from polar or nonpolar solvents, but also for the removal of organic compound from aqueous solutions. Methods of manufacturing and modifying such solvent stable composite membranes are shown, as are the conditioning of membranes and examples of industrial application.
Feststoff‐Bioreaktoren — Teil 2: Bewegte Anlagen
Authors: Vollbrecht Dietmar 
Published: December 2004

AbstractSolid State Fermentation Plant ‐ Part 2: Non‐Stationary Units.Western experience with solid state fermenters in which the fermenting substrate is circulated is still limited to the laboratory scale (< 20 kg of substrate). In contrast, automated industrial plant with capacities of 10 to 100 t of inoculated substrate per charge have been in operation in Japan for several decades for the semi‐continuous production of enzyme mixtures. However, the substrate is only occasionally circulated in these plant. It is shown from the literature cited that stationary solid state fermentation processes employing the tablet method give significantly better results (lower plant costs, shorter process duration, high enzyme product yields, higher product quality, less pronounced gradient formation, etc.) than processes with occasional product circulation. Stationary solid state fermentation plant (tablet method) therefore appear to represent the method of choice, especially for the production of secondary metabolites, pigments, flavours, etc., whose production optima lie within fairly narrow limits which cannot be met by non‐stationary units.
Gasinduziertes Einmischen von Reaktionsstoppern in Behälter mit höherviskosen Flüssigkeiten
Authors: Schimetzek Ralf , Ulonska Armin 
Published: December 2004

AbstractGas‐Induced Admixture of Reaction Inhibitors in Vessels Containing Liquids of Higher Viscosities.This article deals with calculation of the mixing action of gas introduced close to the bottom of vessels containing viscous liquids ( > 10 mPa s). The mixing time required for 95% mixing was determined. This time decreases with increasing volume flow of gas and level of liquid, increasing eccentricity of the point of gas introduction, and decreasing liquid viscosity. With the aid of an analytical model based on fluid dynamics, the mixing time to be expected can be predicted up to – and presumably beyond – a viscosity of 350 mPa s. Only a slight increase in mixing time is to be expected with decreasing interfacial tension and in systems with inhibited coalescence. The results show that gas‐induced mixing of vessels [1–4] is also applicable to high‐viscosity liquids. The approach can also be used for purposes other than admixture of reaction stoppers, such as the admixture of additives in normal operation of reactors and storage tahks.
CAPE in der Praxis — Möglichkeiten und Grenzen aus Nutzersicht
Authors: Lohe B. , Bessling B. , Schoenmakers H. , Scholl S. , Staatz H. 
Published: December 2004

AbstractCAPE in Practice ‐ Opportunities and Limits from the User's Point of View.CAPE tools comprise computer based tools and methods for the design of chemical processes ‐ the use of which is indispensable in modern chemical engineering. This paper discusses the degree to which CAPE is already applied and whether limitations exist. Within BASF, the CAPE framework is provided by the “ProcessNet”, which integrates numerous simulation and design tools. The engineer relies alternatively on inhouse or commercial software. The advantage of CAPE in terms of efficiency depends not only on complex programs, but also to a large extent on the multiple use of intermediate data and program modules. The ProcessNet also features a hierarchical file structure to support the engineer's desktop management. The CAPE environment is being continuously improved. The main constraints on CAPE today are, for example, the missing link between fluid and solid applications, a deficit in data management and the poor state of development of advanced or special programs. The progress of research in this area is followed with great interest.
Systematische vergleichende Kostenanalyse von destillativen und extraktiven Stofftrennverfahren
Authors: Glanz Stephan , Blaß Eckhart , Stichlmair Johann , Punin Anatoli , Balagula Ilja , Victorov Valeri 
Published: December 2004

AbstractSystematic Comparative Cost Analysis of Separation Processes Based on Distillation and Extraction.Rectification is the most commonly used but not always the most economical method of thermal separation. Above all in the case of closely boiling mixtures it becomes very demanding with regard to both equipment and energy. It is often possible to replace rectification by another energetically more favourable separation process such as liquid‐liquid distillation, decantation, or absorption. Owing to the resulting wealth of possibilities for the separation of a mixture it is desirable to gain further knowledge about the economics of individual processes and about the selection of suitable entrainers under given conditions.
Rührtechnik am Ausklang des 20. Jahrhunderts
Authors: Zlokarnik Marko 
Published: December 2004

AbstractMixing at the End of the 20th Century In the light of the rapid and highly successful development of mixing technology during the past 50 years the author presents a terse and critical assessment focussing on open problems and their possible solutions. One of the shortcomings encountered in practice lies in the failure to distinguish between micro‐ and macro‐mixing as fundamental mixing processes. The other concerns the failures attributed to dimensional analysis which actually originate in inappropriate measuring and application techniques.
Floating zone growth of CuO under elevated oxygen pressure and its relevance for the crystal growth of cuprates
Authors: Behr G. , Löser W. , Apostu M.‐O. , Gruner W. , Hücker M. , Schramm L. , Souptel D. , Teresiak A. , Werner J. 
Published: December 2004

AbstractCuO single crystals have been grown from the melt by a floating zone method with optical heating at elevated oxygen pressures 3.5 to 5.5 MPa and growth rates as high as 10 mm/h. Melting experiments and recalculated Cu‐O phase diagram data show that CuO melts incongruently. The melting temperature increases and the concentration difference between the melt and the CuO phase decreases for rising oxygen partial pressure. Accordingly, increasing the oxygen partial pressure improves the growth process by reducing both the significant oxygen loss during melting as well as the composition difference at the growth interface. The results on CuO provide important information for the crystal growth of more complex cuprates. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ X‐ray analysis of MoO3 reduction
Authors: Leisegang T. , Levin A. A. , Walter J. , Meyer D. C. 
Published: December 2004

AbstractThe reduction of MoO3 to MoO2 under hydrogen/argon atmosphere (5 vol. % H2/95 vol. % Ar) in the temperature range 323 K…623 K was studied in situ by means of wide‐angle X‐ray scattering. It has been found that the starting material, MoO3, consists of two different orthorhombic MoO3 phases A and B with nearly the same structure parameters. The phase A (fraction of 37.1 wt%) describes the larger crystallites whereas the phase B (fraction of 62.9 wt.%) describes the smaller crystallites. Under the reduction to monoclinic MoO2 phase during the heating, the thermal evolution of the phase fractions is different. A conclusion is drawn that MoO2 is formed preferably in big crystallites. About 10 wt. % of MoO2 has been found to form at 623 K resulting in about 69 wt. % after cooling to room temperature followed by holding in Ar/H2 atmosphere about 24 h. Additionally, about 4.4 wt. % of the Mo4O11 oxide probably formed in large crystallites was detected in the reduced powder after the cooling. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Void formation in the Cu layer during thermal treatment of SiNx/Cu/Ta73Si27/SiO2/Si systems
Authors: Hübner R. , Reiche R. , Hecker M. , Mattern N. , Hoffmann V. , Wetzig K. , Heuer H. , Wenzel Ch. , Engelmann H.‐J. , Zschech E. 
Published: December 2004

AbstractThe thermal stability of a SiNx passivation layer and its influence on the annealing behavior of an amorphous Ta73Si27 diffusion barrier deposited between copper and SiO2 were analyzed by X‐ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature Tan = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiNx passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiNx/Cu interface, voids in the μm‐range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiNx/Cu interface. The barrier crystallization process into Ta5Si3 occurring during annealing at Tan = 600 °C is principally not affected by the presence of a SiNx passivation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman spectroscopic and X‐ray investigation of stressed states in diamond‐like carbon films
Authors: Krawietz R. , Kämpfe B. , Auerswald E. , Brücher M. 
Published: December 2004

AbstractThe non‐destructive characterization of intrinsic stress is very important to evaluate the reliability of devices based on diamond‐like carbon (DLC) films. Whereas the only requirement for the X‐ray diffraction method is a crystalline state of specimen, Raman spectroscopic stress analysis is restricted to materials showing intensive and sharp Raman peaks. On the other hand, Raman spectroscopy offers the possibility to measure stress profiles with lateral resolution of about 1 micron. The results of stress measurements in DLC films using both X‐ray diffraction and Raman spectroscopy are found in very good correspondence. Mean stress in carbon films consisting of very small crystallites on silicon substrates has been determined by measuring and fitting the stress profiles in the substrate near artificial vertical film edges. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Demonstration of the effect of softening and fire resistance of materials on burning characteristics
Authors: Paul K. T. 
Published: December 2004

AbstractAn important observation during full‐scale fires was that burning behaviour is often determined by softening characteristics as well as ignitability, flame spread, etc. Examples include stacking chairs where thermoplastics give a rapid rate of fire growth and suspended ceilings where thermoplastics reduce fire hazard. A test rig has been progressively developed at RAPRA to reproduce the mechanisms and fire growth rates of stacked chairs and to evaluate the role of softening in fire growth. Although the ignitability of fire‐retarded materials is less than that of non‐fire‐retarded grades, the fire growth rate in stacks is similar and may be related to the softening behaviour determined by exposing sheets of material to radiant heat. The rate of fire growth in stacks may be significantly reduced by modifying the softening behaviour of materials, e.g. by using asbestos‐reinforced thermoplastics which can form an integral, non‐melting felt or by using non‐melting materials such as SMC or wood.