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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 73-86 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As a part of a research project on the mass transfer in liquid pulsed sieve-tray extraction columns (PSE), the diameters and hold-ups of the drops were measured: the drop size using a suction technique, with photoelectric detection, which was adapted to the special boundary conditions of the PSE; the integral hold-up by the pressure difference between the lower and upper parts of the column. Since experimental results cannot be described by known calculation formulae for the Sauter mean diameter and the hold-up, a new method of calculation was developed. It is phenomenologically based on high-speed photographs of the drop motion on a sieve tray. The mathematical-physical model allows the prediction of drop size and hold-up within certain limits, while the possible different operating regimes of the PSE, i.e. the mixer-settler and dispersion regimes can also be estimated.
    Additional Material: 12 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 312-320 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents the methods of measuring the mass transfer in centrifugal extractors and of determining it during the individual life stages of a fluid element of the dispersed liquid, i.e. drop formation, motion, coalescence and stay in the stationary layer of the dispersed phase. The experimental mass transfer coefficients of the dispersed and continuous phases are compared with well-known theoretical models developed for extraction columns in gravitational field. Due to the fast motion and coalescence of the fluid particles at high centrifugal field intensities, mass transfer in centrifugal extractors takes place during short contact times. Nevertheless, this contribution shows that mass transfer in a centrifugal field can be calculated with selected theoretical models of the gravitational field. The investigations on mass transfer are completed by a classification of the strongly deformed fluid particles in centrifugal field into regimes of circulating and oscillating drops. In addition, data on the performance of centrifugal extractors, undergoing several exchange steps, are given.
    Additional Material: 13 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 281-289 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fundamental investigations of coalescence processes in settlers with plate packages for the separation of liquid-liquid dispersions prompted an analysis of the drop motion on the interface of a stratified two-phase flow. Therefore, a physical model was developed, which permits the calculation of drop velocity along the interface of an inclined trickling film. Starting from a balance of forces around a single particle, the model provides the equation of motion for a steady motion of single particles in a stratified two-phase flow. Several assumptions and considerations were necessary to solve this equation, such as taking into account the influence of the wall and of flow resistance. The model calculation assumes Newtonian liquids and laminar, smooth trickling films. A comparison with experimental results confirms that the drop motion behaviour is well reproduced.
    Additional Material: 14 Ill.
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  • 4
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Systematic 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.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 68 (1996), S. 1533-1536 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As a consequence of the structural crisis of German industry, politicians and business leaders are increasingly calling for new and improved products, new and better processes. Innovation is in great demand. Yet what is innovation? How do innovations happen and how can they be promoted? What kind of scientific and technical environment is needed to produce a rich crop of innovations? Good information sources can be an enormous help.
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  • 6
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extraction of plants with the aid of water is one of the oldest techniques known to humankind for obtaining aromatic principles and medicaments from these sources. Extraction vessels excavated in Mesopotamia can be dated back to around 3500 BC, and Sumerian clay tablets describing the preparation of medicaments which were found in the same region date from around 2100 BC. The Greek and Roman civilisations of antiquity inherited extraction together with other skills from their predecessors, and this knowledge was passed on to Christendom by Arabian scholars. Europe of the Middle Ages saw the development of pharmacy, medicine, and mining, as well as the sugar industry, all of which made active use of extraction with a wide range of solvents. Whereas technological applications of extraction were thus steadily increasing prior to the industrial revolution, the equipment used underwent hardly any changes up the end of the 18th century. It was only in the 19th century that active development of equipment, materials, and modes of operation started, while successful combination of theory and practice and treatment of extraction by the methods of engineering science had to wait until the 20th century. This article reports about equipment, solvents, and extraction processes up to the beginning of the present century, and places then in a political and sociological context.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 71 (1999), S. 241-246 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 43 (1971), S. 949-956 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Auf der Grundlage eigener und fremder Versuchsergebnisse wurden der Einfluß des Verhältnisses von Rohr- bzw. Sälendurchmesser D zu Füllkörperdurchmesser dv und der Ringwanddicke s auf den Druckverlust in gasdurchströmten Raschigring-Schüttungen analysiert. Die gewonnene halbempirische Beziehung zwischen dem dimensionslosen Druckverlust, der Reynolds-Zahl und den Geometriedaten gilt für 1,6 〈 D/dv 〈 44; 0,56 〈∊ 〈 0,97; 10 〈 Re 〈 104 und überdeckt damit den anwendungstechnisch bedeutsamen Parameterbereich. Der Vergleich der Druckverluste in Raschigring-Schüttungen mit einem für Vollzylinder-Schüttungen aufgestellten Druckverlustgesetz ermöglicht Aussagen über die Aufteilung der Gasströmung auf die von den Ringen umschlossenen Volumina und auf das von den Ringen nicht belegte Rohrvolumen.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Blasensäulen-Kaskadenreaktoren sind eine investitions- und betriebskostengünstige Alternative insbesondere für die Rührkesselkaskade. Sie sind bevorzugt für reaktionsgehemmte chemische Umsätze geeignet und in der Lage, aufgrund eines engen Verweilzeitspektrums der flüssigen Phase unerwünschte Folge- und Nebenreaktionen zu verhindern. Ihre Eignung für biologische Reaktionen ist hervorzuheben. Die Arbeit berichtet über den gegenwärtigen Stand eigener und fremder Experimente, die bei zweiphasiger Durchströmung hauptsächlich mit dem Stoffpaar Wasser/Luft angestellt wurden. Als feste Phase wurden Sandfraktionen mit einem mittleren Korndurchmesser von 70 μm und 200 μm eingesetzt, bisher jedoch nur als Stoßfunktion, d. h. mit Raumkonzentrationen unter 1%. Die zur Gasdispergierung benutzten Lochplatten hatten kreisrunde Bohrungen, ihre relative freie Lochfläche wurde bisher zwischen 1 und 18% variiert. Die Lehrrohrgeschwindigkeit des Gases wurde zwischen 1,5 cm/s und 45 cm/s, diejenige der Flüssigkeit zwischen 0,05 cm/s und 1,0 cm/s verändert. Die Meßergebnisse des Mindestgasdurchsatzes gegen Rücktropfen, des Flüssigkeitsinhaltes, des Gasdruckabfalls, der Verweilzeitverteilung der flüssigen Phase mit und ohne Rückvermischung und der festen Phase ohne Rückvermischung sowie Stoffübergangs-messungen, die mit Hilfe der Oxidation von wäßriger Na2SO3-Lösung durch Luft angestellt wurden, werden in Diagrammen dargestellt und physikalisch-qualitativ interpretiert. Die quantitative Ergebnisauswertung ist noch im Gange.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird ein Verfahren beschrieben, mit dem die absatzweise Rektifikation binärer Gemische auf einem hybriden Analogrechner simuliert werden kann. Dabei wird vorausgesetzt, daß der Betriebsinhalt der Säule vernachlässigbar gegenüber dem Blaseninhalt ist. Es kann die Zerlegung idealer als auch nichtidealer Flüssigkeitsgemische bei Betrieb mit konstantem oder veränderlichem Rückfluß simuliert werden. Im Programm sind alle wichtigen Parameter wie Gleichgewichtskurve, Dampfstrom, Rücklaufverhältnis, Bodenzahl und Bodenaustauschgrad in einfacher Weise variierbar. Ergebnis der Rechnung sind die unmittelbar interessierenden zeitabhängigen Konzentrationsverläufe von Kopf- und Sumpfprodukt, wobei die erforderlichen Rechenzeiten sehr kurz sind. Mit dem Verfahren werden einige Beispielrechnungen durchgeführt.
    Additional Material: 7 Ill.
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