bluuebunny/crossref_metadata_2025 huggingface dataset:
Rechenprogramme zur Bilanzierung von Anlagen
Authors: Kaufmann Friedrich , Hoffmann Ulrich , Hofmann Hanns
Published: May 2005

Rechenprogramme zur Simulierung und Optimierung werden bei der Bilanzierung einer verfahrenstechnischen Anlage angewendet und bezüglich ihrer Konvergenzeigenschaften und Rechenzeiten verglichen. Zur Bilanzierung von Anlagen im Betrieb auf der Grundlage von Meßwerten werden durch die Minimierung der Fehlerquadrate „beste”︁ Bilanzen berechnet. Dabei können mit statistischen Tests Ausreißer unter den Meßwerten festgestellt werden, die eine Bilanz stark verfälschen.
The determination of enthalpies of sublimation by means of thermal conductivity manometers
Authors: de Kruif C. G. , Oonk H. A. J.
Published: May 2005

This paper describes an investigation into the suitability – for the determination of enthalpies of sublimation of low volatility substances – of thermal conductivity manometers which are operated according to the method described by Engelsman. By making use of the known vapour pressure‐temperature relation of liquid mercury the characteristics of the manometers are obtained. They show deviations from linearity at higher pressures; in spite of this the most suitable manometers still have linear ranges of three to four decades. One of the thermal conductivity manometers (TCM) was used for the determination of the enthalpies of sublimation of benzophenone (ΔsH = 22.60 ± 0.10 kcal mole−1), benzoic acid (ΔsH = 21.05 ± 0.05 kcal mole−1), ferrocene (ΔsH = 17.7 ± 0.4 kcal mole−1) and trans‐stilbene (ΔsH = 24.40 ± 0.15 kcal mole−1). As the measurements on ferrocene fell outside the linear range of the manometer, it was necessary to introduce a correction coefficient derived from the measurements on benzophenone and benzoic acid in order to obtain satisfactory results.
Beschleunigte Strömung von Flüssigkeitsfilmen an ebenen Wänden und in Füllkörperschichten
Authors: Yilmaz Tuncay , Brauer Heinz
Published: May 2005

Zur theoretischen Beschreibung des fluiddynamischen Verhaltens der Flüssigkeitsfilme in Füllkörperschichten wird als Modellvorstellung die beschleunigte wellenfreie Filmströmung an ebenen Platten zugrunde gelegt. Die theoretisch gewonnenen Ergebnisse werden mit Messungen verglichen verglichen und bestätigt gefunden. Untersuchungen über das Einsetzen der welligen Filmströmung bei Beschleunigung führen zu einem allgemeingültigen Diagramm über die verschiedenen Strömungszustände. Hieraus folgt unter anderem, daß die Filmströmung in Füllkörperschichten praktisch immer laminar und wellenfrei ist. Auf dieser Grundlage werden theoretisch begründete Gleichungen zur Berechnung des dynamischen Flüssigkeitsinhalts von Raschigring‐Schichten entwickelt.
Möglichkeiten der Berechnung bei heteroazeotroper Destillation
Authors: Hegner Bernd , Hesse Dieter , Wolf Dieter
Published: May 2005

Die destillative Zerlegung schwierig zu trennender Gemische wird durch Zugabe eines Schleppmittels, das mit der abzutrennenden Komponente ein Heteroazeotrop bildet, erleichtert. Der Zusammenhang zwischen Schleppmittelmenge, Rücklaufverhältnis, Bodenzahl und Trennwirkung kann zur Optimierung der Betriebsparameter und zum Vergleich verschiedener Schleppmittel miteinander durch eine Boden‐zu‐Boden‐Rechnung ermittelt werden; dabei ist zu berücksichtigen, daß in der Kolonne zwei flüssige Phasen auftreten. Zur Darstellung des Gleichgewichts ist die NRTL‐Beziehung geeignet. Das Rechenverfahren wird am Beispiel der Entwässerung von Essigsäure mit Propyl‐ und Butylacetat dargestellt und mit Versuchsergebnissen verglichen.
Abwasserabgabe als monetäre Umweltschutz‐Maßnahme
Authors: Keune Rechtsanwalt Heinz
Published: May 2005

Als erste monetäre Umweltschutzmaßnahme soll eine allgemeine Abwasserabgabe als marktwirtschaftliches Instrument zur Durchsetzung des umweltspezifischen Verursacherprinzips (VUP) zum 1. 1. 1975 mit einem Anfangs‐Satz von 25 DM je Einwohnergleichwert (EGW) und Jahr eingeführt werden, der ab 1. 1. 1979 auf den eigentlichen Satz von 40 DM/EGW Jahr erhöht werden soll. Der ideologische Hintergrund dieser wirtschaftspolitischen Maßnahme und die Anwendung der aus der Ausgestaltung des VUP resultierenden Abgabe werden untersucht. Als Material werden herangezogen der Referenten‐Entwurf eines Abwasserabgaben‐Gesetzes vom 1. 7. 1973/20. 8. 1972 sowie Gutachten, die zur Konzipierung der Abwasserabgabe erstattet wurden, ferner Zahlenmaterial aus dem Bereich der chemischen Industrie und Veröffentlichungen über ausländische Abwasserabgaben. Um die Abwasserabgabe betriebswirtschaftlich tragbar zu machen, empfiehlt es sich, die sog. Restbelastung abgabenfrei zu lassen. Um diese Abgabe volkswirtschaftlich vertretbar erscheinen zu lassen, sollte innerhalb der EWG (Europäischen Wirtschaftsgemeinschaft) eine Harmonisierung vorgenommen werden.
Zur Flockung mineralischer Suspensionen mit Polymeren im Zentrifugalfeld
Authors: Brennecke Klaus , Clement Martin , Trawinski Helmut
Published: May 2005

Es werden zunächst die Einflußgrößen auf die Flockenbildung und Flockenzerstörung von Kaolin‐Suspensionen unter Zugabe von polymeren Flockungshilfsmitteln bei laminarer Scherbeanspruchung in einem Rotationsviskosimeter untersucht. Dabei ergibt sich, daß die Flockenbildung von der Größe und Dauer der Scherung und von der zugegebenen Polymermenge beeinflußt wird, wobei eine Flockenzerstörung kaum stattfindet. Danach werden bei halbtechnischen Versuchen in einer Labor‐Vollman‐telschneckenschleuder dieselben Parameter mit Kaolin‐ und Kohlesuspensionen untersucht. Hierbei konnte bestätigt werden, daß sich die sedimentationsbeschleunigenden Wirkungen von Zentrifugalfeld einerseits und Flockenbildung andererseits bei optimaler Betriebsweise addieren und zu hohem Feststoffausbringen führen. Wegen der turbulenten Durchmischung bei höheren Beschleunigungswerten findet im Dekanter allerdings eine den Trennerfolg der Fest/Flüssig‐Trennung verschlechternde Zerstörung von Flocken statt. Auf Grund von Polymer‐Restkonzentrationsbestimmungen im Zentrifugat des Dekanters wird ermittelt, daß das Zentrifugat für eine nochmalige Flockung im Kreislauf nur dann verwendet werden kann, wenn die mechanische Beanspruchung bei der Feststoffabscheidung einen maximalen Wert nicht überschreitet, so daß im Zentrifugat noch flockungswirksame Polymermoleküle vorhanden sind.
Ein mit Heizpulsen gesteuertes isothermes Kalorimeter. Teil II: Anwendungsbeispiele für kalorische und kalorisch‐kinetische Messungen
Authors: Köhler W. , Riedel O. , Scherer H.
Published: May 2005

Zur Messung von Reaktionsenthalpien sind vor allem die adiabatische Reaktionskalorimetrie und die Verbrennungskalorimetrie bekannt. Eine weitere Methode ist die isotherme Kalorimetrie. Sie hat den Vorzug der technologisch so wichtigen kalorischen und kinetischen Meßbarkeit auch langdauernder Reaktionen. Ein vielseitig und bequem benutzbares Gerät wurde bereits in Teil I vorgestellt. Als Beispiele für Messungen werden nun beschrieben (1.) die Hydrolyse des Acetanhydrids und (2.) die Adsorption von Methylacrylat‐Dampf an Aktivkohle. Beim zweiten Beispiel ergibt sich die Reaktionsenthalpie in der üblichen Weise, nämlich als Zeitintegral der registrierten Leistung, während im ersten Fall die Auswertung auf der Kinetik beruht und damit völlig anders ist.
Gasanalytische Methoden der thermischen Analyse,
Authors: Krug Detlef
Published: May 2005

Es werden die Möglichkeiten aufgezeigt, die sich durch die Anwendung gasanalytischer Methoden bei der thermischen Analyse ergeben. In vielen Fällen können damit mit verhältnismäßig geringem Aufwand zusätzliche Informationen erhalten werden, die in Kombination mit den herkömmlichen Verfahren deren Aussagekraft wesentlich vergrößern. An praktischen Beispielen wird gezeigt, daß oft auch ohne zusätzliche Untersuchungen aus den Meßwerten der gasanalytischen Methoden schlüssige Folgerungen gezogen werden können.
Neue Entwicklungen auf dem Gebiet der Hartstoffe und Hartmetalle
Authors: Kieffer Richard , Ettmayer Peter
Published: May 2005

Die Neuentwicklungen der letzten vier Jahre auf dem Gebiet der Hartstoffe und Hartmetalle werden kurz kommentiert. Neuartige HfC‐ bzw. NbC‐haltige Hartmetalle auf WC‐Basis und WC‐freie (Ti,Mo)C‐basierte bzw. Titancarbonitrid‐Hartmetalle haben sich in der Praxis bewährt, während sich Hartmetalle auf TaN‐Basis noch im Versuchsstadium befinden. Für den schweren Schnitt scheinen Schmelzcarbide (cast carbides) aus dem System TiC‐W besonders geeignet zu sein. Die Beschichtung von Hartmetallen mit Carbid‐ und insbesondere Nitrid‐Schichten hat bereits technische Bedeutung erlangt. Unter Diamantsynthese‐Bedingungen gesinterte polykristalline Diamant‐Werkzeuge sind vor allem zur spanabhebenden Bearbeitung von spröden und schwierig zu bearbeitenden Werkstoffen. geeignet. In der Hartmetall‐Technologie haben sich besonders die Attritor‐Mahlung von Hartmetall‐Ansätzen zur Erzeugung extrem feinkörniger Gefüge, die Sprühtrocknung des Mahlgutes und die heißisostatische Verdichtung von Hartmetallen eingeführt.
Methan‐Gewinnung aus Abfällen
Authors: Rasch Rudolf
Published: May 2005

Sowohl bei der biologischen als auch bei der thermischen Zersetzung von organischen Abfällen entsteht Methan. Die Methan‐Bildung verläuft in der Deponie unkontrolliert. Die Gewinnung von Methan ist dabei unvollständig. Bei der biologischen Zersetzung wasserreicher organischer Abfälle in geschlossenen beheizten Behältern läßt sich gezielt Methan gewinnen. Thermische Prozesse zur Methan‐Gewinnung (Ent‐ und Vergasung) befinden sich noch in Entwicklung. Voraussichtlich werden sie nur in Sonderfällen von Interesse sein. Für die großindustrielle Gaserzeugung aus Abfällen sind die Müllmengen in wirtschaftlich erträglichen Einzugsgebieten zu klein.
Strömungsmechanische Grundlagen der Wirbelschichttechnik
Authors: Werther Joachim
Published: May 2005

Wirbelschichtverfahren werden seit langem in einer Vielzahl technischer Prozesse erfolgreich eingesetzt. Trotzdem bereitet die Auslegung von Wirbelschichten angesichts der komplexen Natur dieser Gas/Feststoff‐Strömung noch beträchtliche Schwierigkeiten. Zwar ist eine überschlägige strömungsmechanische Auslegung auf der Grundlage eines Wirbelschicht‐Zustandsdiagramms möglich und für einige Anwendungen – insbesondere unter den physikalischen Verfahren und nichtkatalytischen Reaktionen – auch ausreichend. Eine genauere Auslegung erfordert aber zusätzlich eine Berücksichtigung strömungsmechanischer Detailvorgänge – z. B. Blasenbildung und ‐wachstum, Gasverteilung durch den Anströmboden und Bewegung des Feststoffs im Inneren der Wirbelschicht – sowie eine Kenntnis der verfahrenstechnischen Möglichkeiten zu ihrer Beeinflussung. Der Stand des Wissens auf dem Gebiet der Strömungsmechanik von Gas/Feststoff‐Wirbelschichten wird dargestellt. Anhand von Beispielen wird die grundlegende Bedeutung der Strömungsmechanik für das Wärme‐ und Stoffaustauschverhalten von Wirbelschichten verdeutlicht.
Detoxikationsverfahren in der Medizin
Authors: Chmiel Horst , Schmidt Klaus G. , Streicher Erich
Published: May 2005

Es wird dargelegt, bei welchen Krankheiten und Stoffwechselstörungen eine apparative Detoxikation bisher versucht wurde, bzw. beim heutigen Stand der Technik aus theoretischen Überlegungen und bisher vorliegenden praktischen Erfahrungen erfolgversprechend sein kann. Am Beispiel der Urämie, bei der sowohl meßbare Größen zur Verfügung stehen als auch ausreichende klinische Untersuchungsmethoden schon erprobt wurden, wird vor allem auf drei Verfahren der Detoxikation eingegangen: Hämodialyse, Hämodiafiltration, Adsorption.
Die Verfahrenstechnik als eine Basis der Planung chemischer Großanlagen
Authors: Futterer Eberhard
Published: May 2005

Schwerpunkte der Verfahrenstechnik beim Chemieanlagenbau sind die Erfassung einer Anlage als System, die Notwendigkeit zur genauen Vorausberechnung infolge steigender Anlagengröße sowie die Wirtschaftlichkeit hinsichtlich der Anlagen‐ und Betriebskosten und der Berechnung selbst. Der Senkung des Rohstoff‐ und Energieverbrauchs kommt besondere Bedeutung zu. Der Anstieg der Anlagenkosten im Zusammenhang damit ist zu beachten. Nach einer beachtlichen Produktionssteigerung der deutschen Chemie in den letzten beiden Jahrzehnten durch die Petrochemie sind heute gezielte Maßnahmen zur Rohstoffsicherung erforderlich. Längerfristig wird man wieder vom Erdöl und Erdgas zurück zur Kohle gehen müssen. Die zukünftige Entwicklung der Verfahrenstechnik wird in hohem Maße von der Nutzung des Computers geprägt sein.
Die selektive katalytische Oxidation von Kohlenwasserstoffen als Herausforderung an den Chemie‐Ingenieur
Authors: Emig Gerhard
Published: May 2005

Bei der Umwandlung der wichtigsten Chemierohstoffe Erdöl und Erdgas in Zwischenund Endprodukte spielt die selektive katalytische Oxidation eine immer bedeutendere Rolle. Dieses Verfahrensprinzip ermöglicht es in vielen Fällen, ältere vielstufige Verfahren durch wirtschaftlichere einstufige Verfahren zu ersetzen. An dem typischen Beispiel der Oxidation bzw. Ammonoxidation von Propylen wird demonstriert, welche Probleme der Chemie‐Ingenieur bei der Entwicklung eines heterogen‐katalytischen Oxidationsverfahrens zu lösen hat. Die besondere Bedeutung einer systematischen Katalysator‐Entwicklung wird hervorgehoben. Allgemeine Gesichtspunkte für die Entwicklung neuer oder Verbesserung bestehender katalytischer Prozesse werden diskutiert.
Grundsätzliche Überlegungen zur Messung der Verteilungen von Partikelgröße und Partikelgeschwindigkeit disperser Phasen in Strömungen
Authors: Raasch J. , Umhauer H.
Published: May 2005

Für die Bestimmung der Häufigkeitsverteilungen von Größe und Geschwindigkeit der Partikeln einer beliebigen Partikelströmung gibt es grundsätzlich zwei verschiedene Möglichkeiten im Sinne zweier verschiedener allgemeiner Meßvorschriften, die im allgemeinen auch zu grundsätzlich verschiedenen Meßergebnissen führen. Die mathematischen Zusammenhänge werden hergeleitet, und es wird gezeigt, unter welchen Bedingungen eine Umrechnung der gemäß den beiden unterschiedlichen Meßvorschriften erhaltenen unterschiedlichen Verteilungen ineinander möglich ist. Ein Maximum an Information erhält man durch simultane Messung von Größe und Geschwindigkeit an den einzelnen Partikeln des Kollektivs. Meßmethoden, die dieses leisten, sind im einen Fall die Doppelimpuls‐Holographie, im anderen Fall eine Kombination von Streulichtpartikelgrößenmessung und Laser‐Doppler‐Geschwindigkeitsmessung.
Informationsverarbeitung und Optimierung in der Analytik
Authors: Eichelberger W.
Published: May 2005

Der Einsatz von EDV‐Anlagen in der Laboranalytik verlangt ein Automatisierungs‐Konzept, das nicht nur die Hard‐ und Software des Computers umfassen sollte, sondern auch die Möglichkeiten in den Laboratorien selbst. Probendurchsatz und mittlere Verweildauer der Probe, Möglichkeiten der Routineanalyse mit automatisch laufenden Geräten, das Verhältnis Vorbereitungszeit/Meßzeit bei einmaligen bzw. komplizierten Proben sowie mittlere und maximale Geräte‐ bzw. Mitarbeiterauslastung müssen ebenso beachtet werden. Für künftige Konzepte wird verteilte Intelligenz für die Datenerfassung und die Auswertung einfacher Proben, eine zentrale Verwaltung und Buchführung sowie zentrale Datenauswertung mit komplexen Programmsystemen für schwierige Proben charakteristisch sein.
Sicherheitsüberlegungen bei der Planung von Chemieanlagen
Authors: Stockburger Dieter , Kühner Heinz
Published: May 2005

Safety considerations in the planning of chemical plant. Viewed from the standpoint of safety engineering the planning of a chemical plant can be defined as follows. Persons and articles of material value are to be protected from thermal, mechanical, and chemical action during the entire lifetime of the plant. Protection must be effective in the plant and in its vicinity. Possible causes of such effects are discussed. Analysis of the causes leads to derivation of the measures to be implemented in order to counter all kinds of failure. A distinction is made between primary or preventive safety measures. They have the aim of avoiding the occurrence of any failure. However, since failure can never be completely ruled out, measures are also outlined which are intended to minimize the consequences of failures. These are called secondary or constructive measures. Various points are considered in detail with the aid of selected examples.
Lagern und Umschlagen von Schüttgütern in der Chemischen Industrie
Authors: Krambrock Wolfgang
Published: May 2005

Storage and trans‐shipment of bulk solids in the chemical industry. Theoretical fundamentals of the motion of bulk solids in bunkers were considered in detail at the Annual Meeting of Chemical Engineers held at Karlsruhe in 1975 [1]. The present account will deal exclusively with practical aspects playing a role in the building and operation of storage and trans‐shipment facilities for bulk solids. Various problems encountered are illustrated for some typical bin storage units in the chemical industry. Moreover criteria are mentioned which can assist the design engineer in the correct choice of silo type and suitable materials of construction, and the ascertainment of the right size of silo. Filling and emptying devices are also proposed for differing spatial circumstances and various tasks. Important ancillary equipment such as ladders, platforms, and devices for monitoring filling levels are also treated. A consideration of the principal regulations governing the operation of silo systems is followed by some hints on the transport, erection, and assembly of silos.
Technischer Stand und wirtschaftliche Chancen der Wirbelschichtfeuerung zur Strom‐ und Wärmeerzeugung aus Kohle
Authors: Schilling Hans‐Dieter
Published: May 2005

Technological state and chances of fluidized‐bed firing for the generation of heat and power from coal. Fluidized‐bed firing provides one of the few possibilities of putting the longterm generation of power and heat from coal on a new technical and economically more interesting footing. It is distinguished, in particular, by being readily rendered ecologically unobjectionable at relatively little extra cost. Research and development in this sector have made enormous progress in recent years, both in the Federal Republic of Germany and world‐wide. This development must visualized, both from the technical and from the economic point of view, as taking place at four levels, the technological state and the economic chances having to be assessed separately. These levels are as follows: (1) Combustion of residues in fluidized‐bed firing; (2) district heating based on fluidized‐bed firing; (3) fluidized‐bed firing in heating stations and heating power stations. An introductory outline of the process engineering principles is followed by a stepwise account of the technical and economic aspects at these four levels.
Mehrstoffverbrennungsanlagen für sperrige Industrieabfälle
Authors: Pauli Balduin
Published: May 2005

Multipurpose incinerators for bulky industrial waste. The rising cost of fuel and power has forced us to develop new and improved methods also in the disposal of bulky industrial waste. A series of factors must be taken into consideration. For the conventional technique of incineration it would at first appear that the efficient disposal of bulky industrial waste presents an almost insurmountable problem. However, practical experience gained on various plants has shown that there are a number of useful solutions to the problem. It is possible to incinerate bulky industrial waste up to certain unit sizes in an ecologically unobjectionable manner. In the long term, considerable economical advantages are forseeable. However, detailed planning is indispensible for the optimization of such processes.
Fluiddynamik des Suspendierens
Authors: Einenkel Wolf‐Dieter
Published: May 2005

Fluid dynamics of suspension. Data of primary interest associated with the use of suspension stirrers are the operating conditions required to suspend the particles of solids and to distribute them in the desired manner throughout the liquid. The tendency to undergo phase separation plays a decisive role in this connection. It has proved convenient in describing the material properties of the suspension to consider the sedimentation properties of the particles in the unperturbed liquid. The question of a scale‐up rule for transferring the suspension state examined in an experimental stirrer to a large scale set‐up has come in for much discussion. The data reported in the literature for the performance per unit volume lie in the range P/V ∼ d0.5, corresponding to the scale‐up rule Fr* = const., and P/V ∼ d−1, corresponding to a constant circumferential velocity wu = const. On the basis of results reported in this paper the recommended scale‐up rule is P/V ∼ d−0.33.
Begasen von niedrigviskosen Flüssigkeiten
Authors: Judat Helmut
Published: May 2005

Gassing of low‐viscosity liquids. The gassing of low‐viscosity liquids is a basic operation frequently encountered in practice; various kinds of apparatus have been developed depending upon the gas load. Of particular importance are the stirred tank and the bubble column because most chemical reactions in the gas/liquid system are performed in these apparatus. This paper is therefore concerned with basic chemical engineering data essential for optimum design of such equipment. Particular attention is devoted to questions of minimum gas throughput. energy requirements, and attainable mass transfer, a distinction being drawn between coalescing and non‐coalescing conditions.
Ionenaustauscher und Adsorber — vielseitige Hilfsmittel der chemischen Industrie
Authors: Martinola Friedrich
Published: May 2005

Ion exchangers and adsorbers – versatile aids in the chemical industry. Ion exchangers and adsorbers are nowadays available in such a wide range of universally applicable or specialist products that they are widely used in industrial chemistry. New applications are discovered each year. Hence their originally predominant use in water treatment has meanwhile been extended and diversified by numerous further applications.
Digitale Prozeßautomatisierungssysteme
Authors: Wüchner Werner
Published: May 2005

Digital process control systems. We are currently witnessing a technical revolution instigated by the microprocessor, which is considerably changing our methods of process control and the design of control rooms. The modern control room presents an entirely different man‐machine interface. CRT's with keyboards and/or light pens for plant control and operation are now to be found instead of instrumental boards. This paper describes the architecture and mode of operation of this new generation of process control systems.
Zur Reaktionstechnik der anaeroben Fermentation
Authors: Wandrey Christian , Aivasidis Alexander
Published: May 2005

Chemical reaction engineering of anaerobic fermentation. Anaerobic fermentation has already been used for more than 50 years for the disposal of excess activated sludge. In recent years, increasing costs and considerable problems encountered in connection with the disposal of activated sludge have encouraged the development of anaerobic processes for the treatment of industrial waste water. Various aspects which have to be taken into account when planning a digester plant are discussed. Reduction in residence time with concomitant increase of biogas production rate is possible by retention of biomass. In this way catabolic performances are obtained comparable to those of aerobic high capacity activated sludge plants. Anaerobic waste treatment appears so far to be a real purification method because the predominant part of the organic pollution (more than 95%) is eliminated under energy saving conditions. The by‐product biogas contributes to the energy self‐sufficiency of the process.
Temporärer Korrosionsschutz von Ausrüstungen für den Bau von Großanlagen außerhalb Mitteleuropas
Authors: Wüstenberg Dieter
Published: May 2005

Temporary corrosion protection for plant construction equipment outside of Central Europe. „Temporary protection against corrosion”︁ consists of measures for the prevention of damage to equipment by corrosion within a given limited period of time. Essentially, it consists in the protection of machinery, apparatus, fittings, pipelines, measuring and control equipment etc. against atmospheric corrosion in the time between the fabrication of such equipment by the manufacturer and its assembly or commissioning by the firm who is to run the plant. A guaranteed protection against corrosion for a period of two years and more is not unusual. Apart from corrosion, the equipment is also subject to mechanical wear and tear. Worth mentioning here are wear and tear due to, inter alia: buffering during transport by rail; rolling during transport by ship; bending and knocking during loading and unloading; compression during stacking in ships holds and in wharehouses; vibration during transportation. These, in part, quite considerable mechanical stresses which the equipment is subjected to should be taken into account, on the one hand when constructing and installing the equipment, and, on the other, when protecting the equipment against corrosion and when packing.
Wechselbeziehungen zwischen Physikalischer und Technischer Chemie
Authors: Wicke Ewald
Published: May 2005

Interactions between physical and industrial chemistry. The most important interactions for the two areas of chemistry are found in the following three fields: (1)states of materials (states of aggregation) and thermodynamics; (2) kinetics of molecular processes as a basis for macroscopic models; (3) methods of testing and measurement and development of equipment. The „classical state”︁ of each of these areas is first sketched out and then the principal developments which are still in course of flux; directions of future development are then deduced. Such directions are exposed to be: extension of the scope of application of supercritical states as solvents and reaction media, as part of a general expansion of industrial application of elevated pressures; increase in knowledge of nonlinear dynamics of chemical systems with regard to transient behaviour and control mechanisms; increase in basic research on molecular structure and dynamics at the interfaces of dispersed systems – especially micelles and catalyst surface – using „in situ”︁ methods, and more extensive utilization of the results in industrial chemistry.
Werkstoffverbund durch heißisostatisches Pressen (HIP)
Authors: Nissel Christoph , Seilstorfer Helmut
Published: May 2005

Bonding of material by hot isostatic pressing (HIP).The HIP process is presented and its applications are described. One of these applications is the gas pressure bonding, which opens up new possibilities in joining materials. The process and the possibilities are demonstrated by some examples. In comparison with other joining techniques, gas pressure bonding is a flexible process. Also the production of parts is possible with little or no machining. The strength of the joint corresponds to the strength of weakest material of the joint if there are no brittle phases. In this case the formation of these phases can be prevented by choosing appropriate parameters, thus ensuring a strong bond.
Chemische Methoden der Abwasser‐Aufbereitung
Authors: Simmler Walter
Published: May 2005

Chemical methods of waste‐water treatment. Chemical methods of waste management by oxidation can be considered for particular effluents whose constituents are degraded too slowly in conventional sewage treatment plants or which interfere with the biodegradation of other substances. Of these methods, those we have to choose from today are, in order of increasing operating temperature: oxidation with hydrogen peroxide – wet oxidation at high pressure – evaporation and combustion. None of these methods is fundamentally better than the others, i.e. none has a maximum ecological benefit coinciding with a minimum economic impact. Detailed experimental work is required to establish the limits and possibilities in each case and thus to form a basis for useful comparisons. Thermal processes are normally ruled out for low concentrations of degradable constituents in waste water because the specific energy costs per unit volume are too high; this is where hydrogen peroxide may offer advantages, especially when the proportion of these constituents fluctuates. With higher concentrations, wet oxidation can be employed; evaporation and combustion are suitable if there is also a high concentration of inorganic salts.
Schwingungserscheinungen in Chemieanlagen
Authors: Gaube Erwin
Published: May 2005

Vibrational phenomena in chemical plant. This article draws on the practical experience of the author to provide a survey of vibrational problems in chemical plant and of their sources. Even though it is not always possible to eliminate all potential sources of vibration by appropriate calculation and design measures during the planning stage, they can usually be quickly identified subsequently by suitable measuring techniques and countermeasures adopted.
Stand und Trend bei der Gesetzgebung zur analytischen Erfassung der Abwasser‐Inhaltsstoffe
Authors: Olivier Manfred , Schendel Frank‐Andreas
Published: May 2005

Current status and future trends in legislation for the analytical determination of the constituents of waste water. If national and supranational regulations are to be translated into enforceable water law (e. g. national water codes), then all those concerned must work together effectively. Experience in recent years gives reason to hope that legislators will take more careful account of scientific factors in the future. The problems of waste‐water analysis are described in the light of the parameters of the waste‐water levy act. The determination of settleable substances serves as a typical example of what is, from the analytical point of view, an unsuitable parameter; the chemical oxygen demand (COD) is determined in accordance with a precisely specified convention. The problems of trace analysis are illustrated in the determination of the heavy metals mercury and cadmium. In the fish test, the peculiarities of biological test methods are demonstrated. In order to ensure that the results of analyses are reliable, it is essential that sampling and preservation be both objective and problem‐related. In the long term, it is important to find ways of reducing the work involved to an acceptable level without any serious loss of information.
Membrandestillation
Authors: Schneider Klaus , van Gassel Thomas Johannes
Published: May 2005

Membrane distillation. In the membrane distillation process, two aqueous liquids of different temperature border on the two lateral surfaces of a hydrophobic (non‐wettable) membrane. The vapor pressure difference resulting from the temperature difference causes vapor molecules to be transported through the pores of the membrane, comparable to an evaporation, transport, and condensation process in distillation. The dependence of this process on various process parameters, possibilities of energy recovery, and application in the fields of pure water production, evaporation of solutions, and recovery of valuable substances are reported.
Sicherheitsbetrachtungen bei der Planung von Chemieanlagen
Authors: Tröster Erwin
Published: May 2005

Safety considerations in the planning of chemical plant. The author shows how the safety concept of a chemical plants is developed on the basis of the process, the properties of the materials, the operating conditions, and the plant location. The basic considerations for a complete and balanced safety concept are addressed. It is demonstrated how, in the case of a large chemical facility, safety considerations undertaken in up to three stages can already ensure the necessary high safety level of a chemical plant during the planning stage.
Die Verfahrensentwicklung im Spannungsfeld zwischen sich rasch entwickelnden Rohstoff‐ und Produktpreisen
Authors: De Beuckelaer Gerard
Published: May 2005

Process development in a atmosphere of rapidly changing prices of raw materials and products. A computer program that allows the analysis of the economic consequences of alternative routes in process development is presented. The program communicates via a user friendly menu system. Single process steps, stored in the data base, can be combined to give systems of almost any desired level of complexity. The advantages and the scope of the program are illustrated by means of two examples.
Mechanische Trennung von Bioprodukten
Authors: Bender Wolfgang , Koglin Bernd
Published: May 2005

Mechanical separation of bioproducts. A great variety of processes and equipment are available for mechanical separation of particles from liquids which have proved of value in the chemical industry or in water treatment. Only a small selection of this broad spectrum of sedimentation, filtration, or flotation processes and equipment can be considered for bioproducts – the limiting factor being the unfavourable separation properties. Only slight differences in density, small particle sizes, and the high compressibility of the filter cakes also require very careful adaptation to the specific separation task.
Abwasserüberwachung als vorbeugender Gewässerschutz
Authors: Frech Thomas
Published: May 2005

Monitoring of liquid effluents as preventative protection of natural bodies of water. One possibility to improve the safety of river water cooling systems is to control the river water side of the cooling system continuously by process analyzers. In this way, leakages in cooling systems can be recognized earlier and the amount of products which contaminate the river water can be minimized. The aim of this article is to inform the user of water cooling systems about the process analyzers which are available. A second aim is to help him to decide which of these analyzers is the best for his measuring problem.
Die Arten der rißbildenden Korrosion und ihre Bedeutung für die Betriebsbereitschaft von Komponenten der Chemietechnik
Authors: Gräfen Hubert
Published: May 2005

Kinds of crack‐producing corrosion and their significance for the availability of components of chemical plants. Interor transcrystalline cracks in metallic components of chemical plants can occur under the combined influence of mechanical stress and corrosion. Since they usually remain unrecognized before the occurrence of visible damage – leakage of a vessel or fracture of a structural part – such crack‐producing corrosion processes are greatly dreaded. Based on differences in the mechanism of the process of damage, one distinguishes two groups, i. e. stress corrosion cracking (SCC) and corrosion fatigue (CF). SCC stands for an interaction between local corrosion attack and quasi‐static tensile stresses (load‐ and/or residual stresses). CF means a combination of mechanical stresses differing in time and corrosion. Hydrogen induced SCC is a special kind of crack corrosion, initiated by atomic hydrogen absorbed in a metal. The paper describes the different systems of SCC and CF, the forms of failure, the parameters, and the possibilities of avoiding damages, especially emphasizing their significance in practice.
Durchflußkontrolle kleiner Dosierpumpen bei stetiger und pulsierender Strömung
Authors: Vetter Gerhard , Christel Wolfgang
Published: May 2005

Flow control for small metering pumps with continuous and pulsating flow. Metering of small flows with high discharge pressure is performed mainly by displacement metering pumps. The necessary mass‐flow control shows problems with pulsating piston‐ or diaphragm metering pumps. A survey explains the presently available continuous and discountinuous methods of mass‐ and volume flow control. Special investigations have been performed with differential scales and mass flow meters based on the Coriolis‐ and the thermal principle. The differential weighing method shows good accuracy down to minimum mass flows of 0.1 kg/h. This method is expensive and requires vibration protected installation. The Coriolis flow meter, applicable over a similar range, precisely integrates the pulsating signal, but requires damping or signal averaging for regulation purposes. Thermal flow meters prove rather sensitive to temperature fluctuations. Under stable conditions and with proper calibration this principle may be applied to flows even below 0.1 kg/h.
Kraftwerke auf der Basis der zirkulierenden Wirbelschicht‐Feuerung
Authors: Hafke Carl , Plass Ludolf , Bierbach Herbert
Published: May 2005

Power stations based on circulating fluid bed combustion. The atmospheric circulating fluid bed (CFB) combustion process for the generation of steam and electric energy must be regarded as fully established and commercially proven based on operating results and plant availabilities achieved to date. This process is especially suitable for the combustion of low‐quality fuels in cases where stringent pollution standards have to be met. Because of a new combustion technique, reduction of emission takes place in the combuster itself (integrated environmental protection), which eliminates the need for flue gas scrubbers. The sole by‐product of a CFB boiler system is a fine, dry ash, which can either be used in the building industry or may be dumped without any problem.
Verfahrensentwicklung durch Kombination von Prozeßsimulation und Miniplant‐Technik
Authors: Buschulte Thomas K. , Heimann Frank
Published: May 2005

Efficient Process Development by Combining Process Simulation and Miniplant Technique. International competition, growing ever fiercer, and product life cycles which are becoming shorter all the time demand a significant contraction times from the chemical industry, of the implementation times from the conception of a product to its market introduction. A significant contribution to rapid and cost‐effective detailed planning of a new production process is provided by the combination of process simulation and an experimental technique developed within BASF AG, i.e. the „miniplant”︁ technique. This article starts by demonstrating the importance of process simulation in the individual phases of process development. It explains the characteristic features of the miniplant technique, what objectives are pursued by employing his technique, and what advantages ccan be achieved, compared with setting up and operating pilot plants. Finally, two examples illustrate that it is possible, by combining process simulation and miniplant technique, to develop processes more rapidely and to scale them up directly from the laboratory to production level.
GVC/DECHEMA‐Ausschüsse „Technische Reaktionsführung”︁ und „Technische Reaktionen”︁
Authors: Schramm Oliver
Published: May 2005

Am 4. und 5. März fand im Karman‐Auditorium der RWTH Aachen unter der Leitung von M. BAERNS (Institut für Angewandte Chemie Berlin‐Adlershof e. V.), H. BOCKHORN (Universität Karlsruhe) und B. KOGLIN (BAYER AG, Leverkusen) die diesjährige gemeinsame Sitzung des GVC‐Fachausschusses „Technische Reaktionsführung”︁ und des DECHEMA‐Arbeitsausschusses „Technische Reaktionen”︁ statt. Die 20 Referenten stellten eine breit gefächerte Palette von Forschungsergebnissen vor.
EUROCARBON '98 in Straßburg
Authors: Scharff Peter , Collin G. , Frohs W. , Van Heek K. H.
Published: May 2005

Die jährlich stattfindende Internationale Kohlenstoff‐Konferenz wurde in diesem Jahr erstmalig gemeinsam von zwei europäischen nationalen Kohlenstoff‐Gruppen, der französischen GFEC und dem deutschen Arbeitskreis Kohlenstoff (AKK) der DKG, als EUROCARBON '98 vom 5.–9. Juli 1998 in Straßburg veranstaltet. Mit mehr als 500 aktiven Teilnehmern und 70 Begleitpersonen aus 30 Ländern fand die EUROCARBON '98 eine überwältigende Resonanz.
Crystallization and Precipitation: The Optimal Supersaturation
Authors: Mersmann Alfons , Löffelmann Michael
Published: May 2005

In this article optimal supersaturation for cooling and evaporation crystallization are presented. This information is based on a simplified model which describes the metastable zone width of activated nucleation. The model assumes that the nucleation step is very fast and the occurrence of the shower of nuclei which is used to define the metastable zone width is caused by the growth of activated nuclei. In future new sensors for the measurement of supersaturation will help to operate batch crystallizers at the optimal supersaturation during the entire batch time.
Estrogen receptor‐α and ‐β immunoreactive neurons in the brainstem and spinal cord of male and female mice: Relationships to monoaminergic, cholinergic, and spinal projection systems
Authors: VanderHorst Veronique G.J.M. , Gustafsson Jan‐Åke , Ulfhake Brun
Published: May 2005

For many populations of estrogen‐sensitive neurons it remains unknown how they are associated with central nervous system circuitries that mediate estrogen‐induced modulation of behavioral components. With the use of double‐labeling immunohistochemistry and tracing techniques, the relationships of estrogen receptor (ER)‐α‐ and ER‐β‐immunoreactive (IR) neurons in the mouse brainstem and spinal cord to monoaminergic, cholinergic, and spinal projection systems are explored. Similar distributions of ER‐IR neurons were present in females and males, with differences in labeling intensity of ER‐α immunoreactivity among males and estrogen‐, and oil‐treated females. Barrington's nucleus, the ventrolateral medulla, and the nucleus of the solitary tract contained spinal‐projecting ER‐α‐IR neurons, whereas ER‐α‐IR neurons in the periaqueductal gray, parabrachial nucleus, and catecholaminergic A1 cell group received spinal input. Numerous tyrosine hydroxylase (TH)‐IR ER‐α‐IR neurons were present in the ventral periaqueductal gray, nucleus of the solitary tract, A1 cell group, and lumbosacral cord. The dorsal raphe nucleus contained ER‐α‐IR and ER‐β‐IR neurons that colocalized with serotonin (5HT), and the reticulotegmental nucleus contained 5HT‐IR ER‐α‐IR neurons. Fibers IR for vesicular acetylcholine transporter (VAChT), TH, and 5HT were located among ER‐α‐IR neurons in the dorsal horn and spinal autonomic regions. Robust staining for TH and VAChT, but not 5HT, was present among ER‐α‐IR neurons in the lumbosacral lateral collateral pathway. Possible modulatory actions of estrogen on each of these ER‐IR populations are discussed in the context of their specific function, including micturition, sexual behavior, ejaculation, cardiovascular and respiratory control, tactile and nociceptive sensory processing, anti‐nociception, endocrine regulation, and feeding. J. Comp. Neurol. 488:152–179, 2005. © 2005 Wiley‐Liss, Inc.
Nucleus retroambiguus‐spinal pathway in the mouse: Localization, gender differences, and effects of estrogen treatment
Authors: VanderHorst Veronique G.J.M.
Published: May 2005

Nucleus retroambiguus (NRA)‐motoneuronal projections are species‐specific and serve expiration, Valsalva maneuvers, vocalization, and sexual behavior. In cat and monkey, estrogen induces sprouting of NRA‐spinal axons. This pathway may thus serve as a model to study mechanisms through which estrogen induces neuronal plasticity. In this study, NRA‐spinal projections are described in adult mice by using anterograde and retrograde tracing techniques, with attention to gender, strain (CD‐1 and C57BL/6), and estrogen‐induced changes (in ovariectomized females). Labeled NRA‐spinal neurons at the level of the decussation of the corticospinal tract were most numerous after tracer injections into the thoracic and upper lumbar cord. They were medium‐sized and had axons that descended through the contralateral cord. A group of small neurons was labeled in the NRA immediately rostral to the decussation of the corticospinal tract after cervical and thoracic, but not after lumbar injections. This group projected mainly via an ipsilateral pathway. The main projections from the caudal NRA involved motoneurons in the thoracic and upper‐lumbar cord that supply abdominal wall and cremaster muscles. Pelvic floor motoneurons did not receive substantial input. NRA‐spinal projections, especially those involving the upper lumbar cord, were sexually dimorphic, being more extensive in males than in females. Moreover, they were more distinct in estrogen‐treated females than in control females. Strain differences were not observed. The unique features of the caudal NRA‐spinal pathway in the mouse are discussed in the framework of possible functions of this system, such as mating behavior and related social behaviors, parturition, thermoregulation, and control of balance. J. Comp. Neurol. 488:180–200, 2005. © 2005 Wiley‐Liss, Inc.
Ephrin‐A2 and ‐A5 influence patterning of normal and novel retinal projections to the thalamus: Conserved mapping mechanisms in visual and auditory thalamic targets
Authors: Ellsworth Charlene A. , Lyckman Alvin W. , Feldheim David A. , Flanagan John G. , Sur Mriganka
Published: May 2005

Sensory axons are targeted to modality‐specific nuclei in the thalamus. Retinal ganglion cell axons project retinotopically to their principal thalamic target, the dorsal lateral geniculate nucleus (LGd), in a pattern likely dictated by the expression of molecular gradients in the LGd. Deafferenting the auditory thalamus induces retinal axons to innervate the medial geniculate nucleus (MGN). These retino‐MGN projections also show retinotopic organization. Here we show that ephrin‐A2 and ‐A5, which are expressed in similar gradients in the MGN and LGd, can be used to pattern novel retinal projections in the MGN. As in the LGd, retinal axons from each eye terminate in discrete eye‐specific zones in the MGN of rewired wild‐type and ephrin‐A2/A5 knockout mice. However, ipsilateral eye axons, which arise from retinal regions of high EphA5 receptor expression and represent central visual field, terminate in markedly different ways in the two mice. In rewired wild‐type mice, ipsilateral axons specifically avoid areas of high ephrin expression in the MGN. In rewired ephrin knockout mice, ipsilateral projections shift in location and spread more broadly, leading to an expanded representation of the ipsilateral eye in the MGN. Similarly, ipsilateral projections to the LGd in ephrin knockout mice are shifted and are more widespread than in the LGd of wild‐type mice. In the MGN, as in the LGd, terminations from the two eyes show little overlap even in the knockout mice, suggesting that local interocular segregation occurs regardless of other patterning determinants. Our data demonstrate that graded topographic labels, such as the ephrins, can serve to shape multiple related aspects of afferent patterning, including topographic mapping and the extent and spread of eye‐specific projections. Furthermore, when mapping labels and other cues are expressed in multiple target zones, novel projections are patterned according to rules that operate in their canonical targets. J. Comp. Neurol. 488:140–151, 2005. © 2005 Wiley‐Liss, Inc.
Mechanisms of subventricular zone expansion after focal cortical ischemic injury
Authors: Gotts Jeffrey E. , Chesselet Marie‐Françoise
Published: May 2005

The rodent subventricular zone (SVZ) contains neural precursor cells that divide and then die in place or migrate to the olfactory bulb through the rostral migratory stream (RMS) to become new neurons. Despite the normally tight control in cell numbers in this region in adults, previous work from our laboratory and others has shown that SVZ cell number increases after a variety of brain injuries. The relative contribution of changes in rostral migration, cell proliferation, and cell death to increased cell number is poorly understood. We examined these parameters after focal cortical ischemic lesions distal from the SVZ in adult rats. Stereological analysis revealed that cell numbers remain constant in the SVZ and RMS until 5 days postinjury but then rapidly expanded by 150,000 cells by day 7 in each region. Rostral migration of SVZ cells was unaffected by the injury. Both cell death and proliferation increased in the SVZ as early as day 5. However, these two mechanisms became uncoupled when cell number increased, indicating that a distant brain injury expands the SVZ by disrupting the balance between cell death and proliferation in this adult neurogenic zone. J. Comp. Neurol. 488:201–214, 2005. © 2005 Wiley‐Liss, Inc.