bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrareinigung organischer Substanzen durch Schmelzkristallisation
Authors: Arkenbout Gerard 
Published: December 2004

AbstractUltrapurification of organic chemicals by melt crystallization. The need for ultrapure organic compounds is increasing fast. Purities up to 99.999 wt% are required for compounds like caprolactam and phenol. Ultrapurification by melt crystallization is promising from a cost‐efficiency point of view, provided that the desired separation can be achieved in a single crystallization operation. When growing the crystals in a suspension a large solid‐liquid interface can be made available, permitting a small rate of crystal growth and reducing the rate of solute incorporation. As a consequence, however, complete separation between crystals and melt has to be established. An efficient crystal‐liquid separation can be attained using so‐called crystal separation columns. Two types can be distinguished: non‐packed and packed columns. In a packed column crystal transport is accomplished using a force like pressure. The separation efficiency of a single crystallization operation could be improved further by recrystallization. When procedures become available which are based not only on experimental experience but mainly on physical and technology knowledge, a broad application of suspension crystallization may be expected.
Prozeßintegrierter Umweltschutz beim Einsatz von Dampfstrahl‐Vakuumpumpen
Authors: Gehring Herbert 
Published: December 2004

AbstractIntegrated environmental protection in the use of steam jet vacuum pumps. At the „cold end”︁ of many processes occurring under vacuum various amounts of water vapour and process steam have to be removed, together with various permanent gases, from the plant at process pressure to atmospheric pressure. The vacuum pump systems required are practically all designed to strictly separate process medium and coolant, to keep the atmospheric burden as low as possible, and also to minimise the work of compression from the point of view of overall operating costs. Thanks to their special features, steam‐driven jet pumps used in conjunction with water‐cooled condensers still represent a straightforward and reliable form of vacuum system. Reduction of the intermediate condenser pressure, separation of coolant and process steam, and coupling with water‐ring vacuum pumps have led to combinations satisfying practically all demands with regard to good energy conversion and best possible environmental protection. In addition, process‐steam driven multistage jet pumps in which condensation of working and suction steam is effected directly by cooled process fluid have also proved of value. They operate in essentially closed circulation from which only a modest flow of waste gases and heat enters the environment.
Rechnerunterstützte Gestaltung und Kostenerkennung von Schweißkonstruktionen
Authors: Pahl Gerhard , Hoffmann Jörg Peter 
Published: December 2004

AbstractComputer‐assisted design and cost assessment of welded constructions. Newly developed functions permit modelling of welded joints in 3D CAD systems. The designer identifies the welding zone and the CAD system suggests appropriate forms and dimensions of welded seams at an early design stage. The user can then correct the proposal if necessary. Detailed information about the welding process can be added later by another specialist or with the aid of an expert system. On utilising the CAD‐assisted selection of raw materials, the costs of the welded joint can be calculated automatically in very detailed form.
Fließinjektionssysteme und Enzym‐Elektroden zur On‐line‐Analytik von Bioreaktoren
Authors: Stöcklein Walter , Bradley Joanne , Bilitewski Ursula , Schmid Rolf D. 
Published: December 2004

AbstractFlow injection analysis and enzyme electrodes for bioprocess monitoring. This review outlines the role played by enzyme electrodes and flow injection analysis (FIA) in bioprocess monitoring. The review is limited to a survey of the application of these systems to the monitoring of physiologically active parameters, such as substrate, product and biomass concentration. Priority is placed on a comparison of the presently available in situ and online techniques including the disadvantages associated with and the advantages offered by each system. An overview of the available sampling systems is given plus their suitability when coupled with FIA for bioprocess monitoring. The survey will be restricted to those techniques which have already been applied to bioprocess monitoring. The review will be illustrated by recent examples of the application of enzyme electrodes and FIA to microbial fermentation and cultivation and animal cell culture.
Möglichkeiten zur Wasserstoff‐Erzeugung mit verminderter Kohlendioxid‐Emission für zukünftige Energiesysteme
Authors: Sandstede Gerd 
Published: December 2004

AbstractHydrogen production possibilities for future energy systems with reduced carbon dioxide emission. All possible hydrogen production methods which are of technical importance or could become technically important have been systematically classified. The conventional processes based on fossil raw materials, as well as hydrogen production from biomass, are considered with a view to the separation of CO2 or the minimization of CO2 emission by using nuclear energy or solar energy, or by using electric energy generated from these primary energies. In addition, possibilities of hydrogen production with carbon separation are investigated. The nonfossil processes using thermal, electric or radiation energy are treated briefly, and water electrolysis is described in more detail. Finally, the hydrogenation of fossil raw materials is discussed, which would lead to mixed carbon‐hydrogen energy systems.
Prozeßführung zur Sicherung reproduzierbarer Qualität in der verfahrenstechnischen Produktion
Authors: Gilles Ernst‐Dieter , Friedrich Martin 
Published: December 2004

AbstractProcess engineering to assure reproducible quality in production. This paper presents an hierarchically structured process control concept in which product quality is regarded as the central orientation factor. The application of control engineering methods is intended to assure maintenance of the product quality specifications. The second part of the article briefly considers the present state of the art of quality assurance. Fundamental considerations concerning a well‐defined quality concept as a basis for process control are presented in the third part, prior to explanation of the process control concept and its illustration with the aid of an example.
Besondere Anforderungen an die Produktionsplanung und ‐steuerung in der chemischen und pharmazeutischen Industrie
Authors: Schürbüscher Dirk , Metzner Werner , Lempp Peter 
Published: December 2004

AbstractSpecial demands on production planning and control in the chemical and pharmaceutical industries. The chemical and pharmaceutical market place is in a phase of structural changes. The decrease of product development times as well as the minimization of production cost are important success factors. Computer based material management and manufacturing planning and control systems also help to improve the efficiency of production. However, systems developed for discrete manufacturing industries are not applicable in chemical and pharmaceutical environments. This paper surveys the specific features of the chemical and pharmaceutical industries concerning production planning and their impact on information technologies.
Kontinuierliche Reaktionsführung mit löslichen Enzymen
Authors: Kragl Udo , Vasic‐Racki Durda , Wandrey Christian 
Published: December 2004

AbstractContinuous processes with soluble enzymes. This paper surveys the use of continuously operating enzyme‐membrane reactors with enforced flow where the retention of soluble enzymes in the reaction vessel is achieved by means of an ultrafiltration membrane. This technique has been commercialized in the acylase process for the synthesis of L‐amino acids on a 200 ton/year level. It is especially useful for the application of multi‐enzyme systems with cofactor regeneration. The synthesis of L‐tert‐leucine from the corresponding α‐keto acid has been achieved on a kilogram scale. Coenzymes coupled to water soluble polymers are retained in the membrane‐reactor together with the enzymes. Use of suitable conditions prevents loss of enzyme and coenzyme by passage through the membrane or by deactivation. Therefore the costs of enzymes and coenzymes are no longer limitations for economic processes. In the continuously operating enzyme‐membrane reactor regeneration of the coenzyme up to 600 000 times was achieved. In continuous peptide synthesis space‐time yields of 25 kg/(l d) were obtained. To suppress side reactions very high catalyst concentrations are possible, yielding residence times below 4 min.
Qualitätssicherung bei der Verfahrensentwicklung
Authors: Krekel Jörg , Polke Reinhard 
Published: December 2004

AbstractQuality assurance in process development. Important decisions pertaining to quality assurance in the chemical industry are already made during process development for new products and improvement of existing processes. This article describes new methods for achieving quality assurance in various phases of process development, both for the process itself and for the desired products. Examples from process engineering with fluids and solids serve to demonstrate the contributions of process engineers to the development of stable and robust processes with regard to quality assurance.
Rohrleitungsplanung und Materialwirtschaft mit unterschiedlichen Datenstrukturen der Rohrleitungsklassen von Anlagenbetreibern
Authors: Diegelmann Ewald 
Published: December 2004

AbstractPipework Planning and Material Management with Differing Data Structures of the Pipe Classes Employed by Plant Users. Engineering quality depends not least on good coordination and smooth flow of information between the individual disciplines. A major aim of CAD – apart from rationalization – is to improve the quality of engineering work. This is why all the plant users and engineering firms have introduced computer systems to support their piping work. Pipe classes had to be stored in accordance with the data structures prescribed by the respective computer systems. This has led to differences in the definitions of piping items. Different identifiers and data structures are an obstacle to cooperation. Economic aspects and comprehensive documentation requirements imposed by new regulations call for suitable structures to ensure smooth data flow between the various systems.
Produktintegrierter Umweltschutz in der chemischen Industrie – Chancen und Grenzen
Authors: Christ Claus 
Published: December 2004

AbstractBei der Herstellung von Chemieprodukten fallen im Produktionsprozeß häufig Stoffe an, die vom Produzenten nicht angestrebt werden. Sie werden als Rückstände oder Reststoffe bezeichnet. Die Minimierung dieser Stoffe ist Bestandteil des unternehmerischen Umweltschutzes. Am Beispiel der chemischen Industrie wird gezeigt, wie diese ökologische Zielsetzung mit dem Konzept des produktionsintegrierten Umweltschutzes erreicht wird, welche technischen Maßnahmen dazu durchgeführt werden, zu welchem Ergebnis diese führen und welche Grenzen sich hierbei ergeben. Die damit verbundene Kostensituation wird ebenfalls dargestellt.
Dynamisches Verhalten durchgehender Reaktionen in nicht durchmischten Systemen
Authors: Schuler Hans 
Published: December 2004

AbstractIn dieser Arbeit sind die Ansätze dargestellt, die zur Beschreibung des dynamischen Verhaltens von durchgehenden Reaktionen in inhomogenen Systemen verwendet werden. Der wichtigste Ansatz geht auf Frank‐Kamenetzki zurück und beschreibt das Durchgehen von wärmeleitenden Reaktionssystemen. Die grundlegenden Gleichungen dieser Theorie haben breiten Eingang in Versuchsauswertung und Apparate‐Dimensionierung gefunden. Die in dieser Arbeit angegebenen Modifikationen und Erweiterungen der elementaren Theorie geben wichtige Hinweise auf allgemeinere Deutungen experimenteller Ergebnisse und auf fundiertere Auslegungsformeln für speziellere und praxisnähere Bedingungen. Diese Modifikationen der Theorie sollen anregen, auch in der Sicherheitstechnik zu differenzierteren Betrachtungen der Reaktionen und der Transportprozesse zu gelangen.
Mikrowellen‐Trocknung – Grundlegende Untersuchungen und Scale‐up
Authors: Stammer Achim , Schlünder Ernst‐Ulrich 
Published: December 2004

AbstractDie Trocknung wasserfeuchter Festkörper mit Mikrowellen stellt eine Ergänzung zu den konventionellen Trocknungsverfahren dar. Aufgrund hoher Investitions‐ und Energiekosten erfolgt der Einsatz nur in Sonderfällen. Die Produktqualität hängt im wesentlichen von den Feuchte‐ und Temperaturverteilungen ab, die während der Trocknung im Gut vorliegen. Bei der Mikrowellen‐Trocknung wasserfeuchter Güter steigt die Temperatur in der Regel von der kältesten Stelle an der Gutsoberfläche zum Inneren des Gutes hin an. Dementsprechend ist die lokale Gutsfeuchte in der Gutsmitte am niedrigsten, wo die Temperatur am höchsten und die Energiezufuhr (aufgrund einer Fokussierung der Mikrowellen) am größten ist. Ziel dieser Untersuchung ist die Ermittlung von Trocknungsverlauf, Temperaturverlauf und Feuchteverteilung sowie der Voraussetzungen für ein Scale‐up. Dazu wird ein Berechnungsmodell vorgestellt, an Hand dessen wichtige Einflußgrößen auf die dargestellten experimentellen Ergebnisse diskutiert werden.
Absorption von Stickstoffdioxid und Schwefeldioxid aus Rauchgasen
Authors: Pirkl Hans‐Georg , Hofmann Hanns 
Published: December 2004

AbstractEs werden einige wesentliche Reaktionen beschrieben, die bei der absorptiven Entfernung von NO2 und SO2 aus Kraftwerksrauchgasen nach einem an das Ammoniak‐Simultanverfahren von Walther angelehnten Prozeß eine Rolle spielen. Als Laborreaktor dient eine bezüglich beider Phasen kontinuierlich arbeitende Doppelrührzelle, deren physikalisches Stofftransportverhalten durch die Absorption von SO2 charakterisiert wird. Es zeigt sich, daß für die Abhängigkeit des Stofftransport‐ vom Diffusionskoeffizienten folgende Gleichung gilt: kx ∝ Dx0,67. Die Absorption von NO2 bei Partialdrücken unter 100 Pa ist eine schnelle irreversible Reaktion, wobei der gasseitige Stofftransport praktisch allein durch die Spezies NO2 verursacht wird. Die Koabsorption von NO2 mit SO2 zeigt eine vernachlässigbare Veränderung der Stoffstromdichten gegenüber den Einzelabsorptionen. Auch ein Zusatz von Wasserstoffperoxid in die Waschlösung wirkt sich kaum beschleunigend auf die NO2‐Absorption aus, jedoch reduziert er die Sekundäremission von NO.
Einfluß der Produkteigenschaften auf die Trocknung
Authors: Liedy Werner 
Published: December 2004

AbstractInfluence of Product Properties on Drying. A number of items of information are required for selection and design of a drying process. Thermodynamic equilibrium as well as heat and mass transfer are the traditional prerequisites for describing the drying operation. In the development of a drying process further specific properties of the product must be known. These properties, such as chemical reactions or sticking properties, greatly reduce the number of possible drying processes. For this reason, the measurement of these properties plays an important role in the development of a drying process. Many of the bench scale tests in use do not have a physical basis, but have been developed empirically because the physical context is often unknown. Yet a number of physically well‐defined methods are available for product characterization. In practical work a combination of empirical and scientifically defined methods is used.
Lichtbogen‐Plasma‐Reaktor für die Herstellung von Acetylen aus Kohle
Authors: Brachold Harald , Peuckert Cornelius , Regner Hans 
Published: December 2004

AbstractPlasma Furnace for the Production of Acetylene from Coal. At Hüls AG in cooperation with DMT GmbH and sponsored by the Land of North Rhine‐Westphalia a process for manufacturing acetylene via the pyrolysis of coal in an electric arc plasma reactor has been developed. At sufficiently high temperatures acetylene is the compound formed in preference to other hydrocarbons. The decomposition into C and H2 in a consecutive reaction has to be avoided as far as possible by “freezing” the reaction at a high C2H2 concentration level. The performance of the reaction is determined by extreme conditions with regard to high temperatures (> 2000 K) and short residence times (only a few ms). If coal is the feedstock, the pyrolysis reaction of the hydrocarbon to acetylene is preceded by the heating up of the coal particles (< 100 μm) and the release of their volatile constituents. This contribution reports upon the developments in reactor design on the pilot scale (up to the power of 1,5 MW) and the results arrived at and experience acquired in this work, with a view to elaborating a process for coal‐based acetylene manufacture.
Grenzbelastung von unpulsierten Füllkörper‐Kolonnen bei der Flüssig/Flüssig‐Extraktion
Authors: Maćkowiak Jerzy 
Published: December 2004

AbstractDetermination of the Limit Load of Non‐pulsated Packed Columns for Liquid‐Liquid Extraction. Mersmann developed a flood point diagram to determine the limit load of different types of extractors. This contains the rising or falling velocity of an individual droplet as the intermediate quantity. In the flood point diagram valid for packed columns, there is a shaded area of possible load limits instead of a loading curve. In this paper statements about the limit of load of non‐pulsated packed columns are focussed by giving a limit line for the mass transfer direction C → D and another for that of D → C. Both the limit lines are within the shaded area given by Mersmann. In the modified flood point diagram, a new relationship for the rising or falling velocity of the individual droplets in a packed bed is used as the intermediate quantity. The validity of this has already been proved for gas‐liquid systems.
Druckschwingungen durch oszillierende Verdrängerpumpen in Rohrleitungssystemen
Authors: Vetter Gerhard , Seidl Bernd 
Published: December 2004

AbstractPressure Pulsations Caused by Reciprocating Pumps in Piping Systems. The safe design of piping installations for reciprocating pumps requires proper knowledge about the pump/installation interaction. In many cases critical resonance effects can be avoided by proper piping geometry or improved pump performance with respect to the volumetric efficiency (primary measures). Normally it is necessary to use various secondary dampening methods which can influence the acoustics of the piping system. Several examples of experimental computer simulations of damper action – upstream and downstream – are presented for fluidand gas‐filled damper versions. The influence of entry geometry of the dampers is explained, hints on the proper geometry of the entries are given and the effects of various dampers and their influence on the total acoustics are discussed. Special reference is made to the effect of orifices as dissipative and acoustic elements in piping systems. The investigation shows the importance of analyzing of the total system of pump, piping installation and vessels or reactors and the application of computer simulation for piping design.
Parameterbestimmung bei linearen chemischen Prozessen
Authors: Blume Thomas , Prüß Jan , Warnecke Hans‐Joachim 
Published: December 2004

AbstractDetermination of Parameters in Linear Chemical Processes. The authors describe a straightforward and extremely reliable method for determination of the physicochemical parameters occurring in mathematical models of chemical processes. It is based on the restrictive assumption that the system considered is linear and the number of parameters is small. These assumptions permit a detailed eigenvalue analysis of the system, permitting a complete insight into its behaviour. The eigenvalues λk and the factors ak of the corresponding exponential functions are determined by curve fitting. These in turn are determined by system parameters and thus afford relations from which the latter can be calculated. Use of the proposed model requires the design of experiments which can be described by approximately linear models. This is indeed possible in many cases.
Phasen‐Doppler‐Anemometrie zum Bilanzieren und Modellieren mehrphasiger Strömungen
Authors: Bauckhage Klaus 
Published: December 2004

AbstractPhase Doppler Anemometry for Balancing and Modelling of Multiphase Flow. Diffraction, refraction, and reflection are components of the light scattered on interaction with dispersed systems. They lead to differing measurable phenomena and are utilised for the characterisation of particle properties in multiphase flow. The property of greatest interest is the particle size. Contact‐ and reaction‐free optical laser measuring methods suitable for in‐line measurements, such as phase Doppler anemometry, utilise light scattered by the particles in order to determine their size and velocity, and also to some extent for the determination of other dispersion‐related or kinetic particle properties. This is illustrated for the case of phase Doppler anemometry.
Partikelmeßtechnik Status, Trend – Bedarf
Authors: Polke Reinhard , Rädle Matthias , Scholz Norbert 
Published: December 2004

AbstractParticle Measurement, State of the Art, Trends – Needs. An excellent overview of the various goals of particle technology, which have long extended far beyond particle size analysis, is provided by POWTECH. The following examples should serve to illustrate the scope of such measurements and the trends noted in this area: measurements for the monitoring of clean rooms; measurements supporting process engineering developments; and process analysis. There is wide range of instrumentation available for the assessment of dispersed product states. Based on proven principles these instruments are becoming more user friendly and available with improved data evaluation; the methods of evaluation are, unfortunately, still not clear to the user. The current trend is in two directions: (1) simultaneous acquisition of several measurements for more accurate determination of the required quantity or for determination of two different quantities and (2) on‐line or in‐line measurement, which has to be fast, economical, and safe.
Wissenschaftlichtechnische Fachgesellschaften in sich verändernden Umwelten
Authors: Staudt Wolfgang 
Published: December 2004

AbstractScientific and Technical Societies in Changing Environments. The role of science and technology has been subject to change during the development of modern societies. The application of scientific knowledge and technological innovations is now taken for granted in many sectors of society. Yet the scientific and technological transformation of modern society is not proceeding without conflict. As a result, science and technology have become political issues. Members of society no longer unquestioningly accept the scientific and technical changes to their way of life and work; instead they wish to exert a modifying and limiting influence on developments. Demands arise for orientation of research towards the needs of society. Traditional autonomy is required to make way for a responsible utilisation of the possibilities of science and technology. This article attempts to establish the role of learned societies in dealing with these problems.