bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Risikoanalysen in der chemischen Industrie
Authors: Joschek Hans‐Ingo , Helmstädter Gerhard , Dehler Jürgen , Langensiepen Hans‐Werner
Published: December 2004

Quantitative risk analysis in the chemical industry. Consideration of risks on a qualitative basis is a useful, generally applied tool in safety engineering. However, attempts to quantify risk create problems. Quantifying studies have been published concrning nuclear and chemical plant, storage tanks, and port and transport facilities. At present, attempts are also being made in Germany to demonstrate that quantitative risk analysis is also possible for chemical processes. Instead of relying on past empirical values, an ab initio determination of risk from model calculations is being tried. A theoretical basis is already available for such calculations. However, practical execution and simplification of the complicated methods leads to numerous problems which are discussed in this paper. With the aid of selected examples attention is focussed on the following problems: (1) consideration of maintenance; (2) quality of starting data; (3) predictive power of weak‐point analysis.
Wärme‐ und Stoffübertragung in Festbetten
Authors: Gnielinski Volker
Published: December 2004

Heat and mass transfer in packed beds. The calculation of heat transfer in packed beds and between packed beds and the surrounding walls requires knowledge of numerous different parameters, since heat is transferred by conduction as well as by radiation and convection. If it is necessary to distinguish between particle‐ and fluid‐temperature the heat transfer is described by a system of coupled differential equations. The differential equations are based on a heterogeneous model. The currently accepted transport coefficients needed to solve the differential equations are reviewed. The simpler case in which distinction between fluid and particle temperature is unnecessary is described by the homogeneous model. Only two transport coefficients are needed here for the calculation of the temperatures and the transferred heat, namely the effective conductivity of a packed bed and the wall heat transfer coefficients. Literature references to these coefficients are reported.
Prozeßsystemtechnik — Gedanken zu Notwendigkeit und Inhalt einer akademischen Lehre
Authors: Blaß Eckhart , Gelbe Horst , Muthmann Erhard , Vogel Ludwig
Published: December 2004

Process System Engineering. Thoughts on the need for and curriculum of an academic course of instruction. The raw material, energy, and environmental situation, international competition, and the decline in product innovation are increasingly casting doubts on conventional processes and their realization. Hence, in the future‐training of chemical engineers a reasonable amount of time should be devoted to the study of system facets, i. e. to thinking and acting in complex systems of interrelationships. Under the general leading „Process System Engineering”︁ those activities are discussed which are relevant to the design and planning of chemical engineering systems (process synthesis) and the mathematical analysis of a given system (process analysis). Process synthesis is the creative facet of project planning involving several methodologies. Process analysis embraces steady‐state and non‐steady state mass‐ and energy‐balancing and the mathematical evaluation of various process alternatives on the basis of operating costs and investment as well as the simulation of operational behaviour and optimization of process configurations using mathematical models. The following article discusses a selection of points which should play an important part in the teaching of process synthesis and process analysis and considers some examples by way of illustration.
Die Abscheidung von Partikeln aus Gasen in Faserfiltern
Authors: Löffler Friedrich
Published: December 2004

Particle collection by fibrous filters. Technically employed fibre filters can be classified according to their construction and application in two major groups: deep bed filters and fabric filters. Approaches to the calculation of the collection efficiency for both types of filters start from a clean nondusted filter layer. From this one examines only the initial state, which is especially critical, while the degree of collection as a rule becomes better with increasing dust accumulation. Various models are available for the calculation of the pressure drop. The initial pressure drop for deep bed filters can be calculated with the help of the resistance model. Especially important are those estimates, which for purification filters describe the pressure drop or the gas flow with increasing dust accumulation, because these equations can serve directly for the dimensioning of filter plants. Of courese, characteristic permeability values for filter fabric and dust layer must be determined beforehand. The possibilities and problems of these calculations, as well as open questions, will be discussed.
Kosten der Staubabscheidung
Authors: Reinhardt Heinz , Löffler Friedrich
Published: December 2004

Costs of dust removal. The costs incurred in ensuring efficient removal of dust in industrial processes are directly related to current legal regulations. A tightening up of these regulations can necessitate the selection and operation of more highly efficient separators, improvement in the efficiency of dust removal with existing equipment, or the installation of a revolutionary and comprehensive gas cleaning technique. The economic aspects of these alternative approaches are outlined with the aid of three examples taken from different branches of industry. Of paramount importance in all dust collection problems is the “dedusting situation”, defined by the interconnection of production process, dust collector and requisite auxiliaries. There are also further technical and economic parameters. The most important economic parameters are capital investment and operating costs, or total running costs per year. A formula for the computation of annual costs is established and the annual costs for two dust removal techniques are analysed.
Sauerstoff‐Verzehrkathoden für die Chloralkali‐Elektrolyse
Authors: Yeager Ernest , Bindra Perminder
Published: December 2004

Oxygen‐consuming cathodes for alkali chloride electrolysis. Considerable energy saving can be accomplished in alkali chloride electrolysis if an oxygen‐consuming cathode is used in place of one liberating hydrogen. An overall cell potential saving of ca. 1 V is possible. In particular, diaphragm cells are suitable for air cathodes owing to the high purity of the catholyte. A possible altenative to the use of an in‐situ air cathode is the use of hydrogen/air fuel cells, such as the phosphoric acid system of United Technologies, for electrochemical utilization of the hydrogen. The operating temperature is then 200 °C at most. The waste heat can be utilized for evaporation of, e.g., diaphragm cell caustic soda; this acid system also requires no prior air purification. However, the gain in energy is only two thirds of that accomplished with an in‐situ cathode. At present, great effort is being invested in the development of favourably‐priced air cathodes with long lifetimes in concentrated caustic soda; apart from platinum, numerous transition metal complexes are being tested for this purpose.
Methanisierung kohlenmonoxidreicher Gase beim Energie‐Transport
Authors: Harms Hans , Höhlein Bernd , Skov Allan
Published: December 2004

Methanization of carbon monoxide‐rich gases for energy‐transport. The partners of the NFE project (Nukleare Fernenergie, Remote nuclear energy) – Kernforschungsanlage Jülich GmbH (Germany) and Rheinische Braunkohlenwerke AG, Köln (Germany) – in collaboration with Haldor Topsøe A/S, Copenhagen (Denmark), have investigated various problems of the methanization of synthesis gases rich in carbon monoxide. Preliminary results obtained from trial operations with the pilot‐scale methanization plant ADAM I at KFR Jülich and from the catalyst‐development project at Haldor Topsøe A/S are reported. A detailed account is given of the catalyst investigations carried out on the Haldor Topsøe pilot plant for the further development of the TREMP process for SNG manufacture and of the complementary catalyst investigation in the NFE project at the Union Rheinische Braunkohlen Kraftstoff AG and the Kernforschungsanlage Jülich GmbH for the optimization of the methanization process in the remote energy system EVA‐ADAM. In the pilot plant ADAM I, a three‐stage methanization process with product gas recycling and maximum temperature of 600 °C utilizing synthesis gas from methane vapour reforming (EVA) has been demonstrated for the first time. In further experiments to be carried out with ADAM I the influence of operating irregularities on the behaviour of the methanization plant and the dynamics of the remote energy system will be investigated, data for the preparation of mathematical models collected, new components tested, and the process of methanization optimized.
Verfahren zur Kristallisation aus Lösungen
Authors: Schliephake Dietrich
Published: December 2004

Crystallization from solution. In general the processes occurring in crystallizers have previously been treated in only summary and phenomenological manner because only little was known about the joint action of the individual steps. An attempt has therefore been made, in the present survey, to examine the relationship between the physico‐chemical properties of the relevant system, the process chosen, and engineering economics.
Naßoxidation — Ein Beitrag zum Stand der Technik
Authors: Perkow Helmut , Steiner Rudolf , Vollmüller Helmut
Published: December 2004

Wet air oxidation – Present‐day technology. Wet air oxidation is a process of flameless “incineration”, especially of organic compounds, in an aqueous phase with air or other oxidants at relatively high temperatures and pressures. Existing applications such as the sanitizing of sewage sludge, processing of sludges from pulp production, and regeneration of activated charcoal are described. At present, waste water purification by wet air oxidation is being propagated. Difficult degradation of some pollutants enforces the use of temperatures up to 330°C and pressures up to 250 bar. The high investment costs for such plants, which require materials like titanium or hastelloy to handle corrosive wastes, often result in higher operating costs than with other methods, in spite of low energy consumption. Once the effectiveness of existing plants has been proved, especially regarding corrosion problems, rising demands for waste water purification may render wet air oxidation increasingly important.
Gasreinigungsverfahren für große Wasserstoff‐Mengen
Authors: Werner Dietmar
Published: December 2004

Wasserstoff wird schon heute weltweit in sehr großen Mengen erzeugt. Seine Bedeutung wird mit der Umstellung der Energiewirtschaft vom Erdöl zu anderen Energieträgern noch wachsen. Es wird eine Darstellung und kritische Betrachtung der vorhandenen Technologien zur Reinigung von Wasserstoff gegeben unter besonderer Berücksichtigung neuer Entwicklungen wie der Druckwechsel‐Adsorption und der Diffusion an synthetischen Hohlfasern.
Konzeption und Wege des Explosionsschutzes
Authors: Steen Henricus
Published: December 2004

Aufbauend auf dem Wahrscheinlichkeitsprinzip wird die „Philosophie”︁ des heute angewendeten Explosionsschutzes beschrieben. Grundlagen und einschränkende Bedingungen des primären Explosionsschutzes (Vermeidung gefahrdrohender Mengen explosionsfähiger Gemische) werden dargelegt. Der Umfang des sekundären Explosionsschutzes (Vermeidung von Zündquellen) richtet sich nach der ortsabhängigen Wahrscheinlichkeit des Auftretens explosionsfähiger Gemische, die zur Festlegung explosionsgefährdeter Bereiche und zu deren Einteilung in Zonen führt. Mögliche Rückwirkungen der zu erwartenden Explosionsschäden auf die Zoneneinteilung werden erläutert.
Medizinische Verfahrenstechnik
Authors: Chmiel Horst
Published: December 2004

Viele verfahrenstechnische Grundvorgänge beruhen auf Transportvorgängen, z. B. aufgrund vorhandener Temperatur‐, Druck oder Konzentrationsdifferenzen. Diese Transportvorgänge finden vielfältig im gesunden Kreislauf statt. So liefern Verbrennungsprozesse dem menschlichen Körper die erforderliche Wärme. Das Herz als Blutpumpe sorgt für eine optimale Durchströmung aller Gefäße. In der Niere erfolgt an hochkomplizierten biologischen Membranen durch Stoffaustauschprozesse eine Entgiftung des Blutes.

Es liegt daher nahe, den Verfahrensingenieur für die Lösung einer Vielzahl in der Medizin auftretender verfahrenstechnischer Probleme heranzuziehen. Typische Aufgaben sind: Charakterisierung des Fließverhaltens von biologischen Fluiden, die Erforschung der Wechselwirkungen zwischen Blut und körperfremden Materialien mit dem Ziel, für den temporären oder permanenten Einsatz geeignete Werkstoffe zu finden, oder die Entwicklung von Blutpumpe, künstlicher Lunge, künstlicher Leber und künstlicher Niere.
Gütesicherung bei Fertigung und Montage von Rohrleitungen
Authors: Fiehn Harald
Published: December 2004

Bei Fertigung und Montage von Rohrleitungen müssen außer den situationsbedingten und sachlichen Fehlerursachen auch die verhaltensbedingten Fehlerquellen berücksichtigt werden, damit die technische und menschliche Fertigungssicherheit im notwendigen Umfang gewährleistet werden kann. Behandelt werden hierbei folgende Einzelheiten: Bestellangaben, Fertigungsangaben, Fachpersonal, Fertigungseinrichtungen, Kontrollschritte zur Absicherung des Fertigungserfolges und Kontrollumfang in Abhängigkeit von der erforderlichen Qualitätsstufe. Mehrjährige Aufschreibungen über Fehlerquoten bei Rohrleitungsschweißarbeiten dienen zur Diskussion des notwendigen Kontrollumfangs. Die entstehenden Kontrollkosten werden für die Modellfälle personenbezogene Überwachung und objektbezogene Überwachung gegenübergestellt. Auf typische Ausführungsfehlerwird hingewiesen. Praxisbewährte Arbeitsrichtlinien sind vorhanden und enthalten auch eindeutige Qualitätsanforderungen. Die Basisunterlagen für eigenverantwortliches Handeln stehen somit zur Verfügung.
Ausbreitung von Abgasfahnen
Authors: Schönbucher Axel , Scheller Volker
Published: December 2004

Zur Ausbreitung luftfremder gasförmiger Stoffe in der Atmosphäre werden die wichtigsten experimentellen Untersuchungsverfahren sowie wesentliche mathematische Modellvorstellungen besonders von Gauß‐Modellen dargelegt. Dabei wird insbesondere die Einwirkung der von meteorologischen Einflüssen geprägten konvektiven und turbulenten Eigenschaften der Atmosphäre auf die Ausbreitung von Abgasfahnen behandelt. Ein äquidensitometrisches Meßverfahren hat gezeigt, daß die Langzeitstrukturen einer Raffinerie‐Rußfahne im norddeutschen Raum mit einem Gauß‐Fahnenmodell quantitativ beschrieben werden können. Hieraus ergeben sich die für alle Ausbreitungsmodelle fundamentalen Streuungsparameter bzw. Austauschgrößen, deren Entfernungsabhängigkeit und Größenordnung aus der äquidensitometrischen Ballenstruktur der Abgasfahnen verständlich wird.
Biokältetechnik: Verfahren der Gefrierkonservierung in der Medizin
Authors: Scheiwe M. W. , Rau G.
Published: December 2004

Das Verfahren der Gefrierkonservierung beinhaltet die Überführung der flüssigen Substanz in eine feste, gefrorene Phase und die Umkehr dieses Vorganges. Das Ziel ist die möglichst vollständige Erhaltung der Ausgangseigenschaften des biologischen Materials, insbesondere der Lebensfähigkeit und der Ausbeute lebender Zellen, wie z. B. Blutkörperchen, die in der Medizin gezielt therapeutisch verwendet werden sollen. Diese Arbeit soll exemplarisch den Weg aufzeigen, der von der gestellten Aufgabe zur verfahrenstechnischen Lösung führt. Anhand der Physikochemie des Gefriervorganges der vorliegenden Kochsalzlösungen und involvierten, osmotisch reagierenden Zellen werden die Bedingungen für günstige Prozeßführung und die geschwindigkeitsbestimmenden Schritte dargelegt. Die hieraus folgenden technischen Problemstellungen sind Wärmetransport an Flüssig‐Stickstoff, instationäre Wärmeübertragung gefrierender Körper und Auslegungskriterien für technisches Gefrieren. Schließlich werden Gefrier‐Konservierungsprozesse und Ergebnisse der besonders aktuellen Anwendungsgebiete, nämlich rote Blutkörperchen für Katastrophenfälle und weiße Blutkörperchen für die Krebstherapie, aufgezeigt. Als konkretes Beispiel wird eine erst durch die Gefrierkonservierung ermöglichte Verbesserung der Tumortherapie aufgezeigt.
Der Ethylenoxid‐Prozeß und die Regenerierung des dabei verwendeten Silber‐Katalysators
Authors: Rebsdat Siegfried , Mayer Sigmund , Alfranseder Josef
Published: December 2004

Ethylenoxid ist ein bedeutendes Zwischenprodukt der chemischen Industrie und wird durch Direktoxidation von Ethylen mit Sauerstoff über einem Silber‐Trägerkatalysator gewonnen. Die bei diesem heterogen katalysierten Prozeß eingesetzten Silber‐Katalysatoren unterliegen einer Alterung, so daß sie in bestimmten Zeitabständen in einem ums‐tändlichen Verfahren ausgetauscht werden müssen. Die Alterung der Katalysatoren verursacht deshalb hohe Kosten und Materialverluste. Das hier beschriebene Verfahren bietet alternativ die Möglichkeit zur Regenerierung von gealterten Silber‐Katalysatoren durch eine Imprägnierung mit Cäsium. Dadurch werden erhebliche Einsparungen sowohl an den Einsatzstoffen Ethylen und Sauerstoff als auch am Katalysator‐Material erzielt. Das Verfahren hat sich mittlerweile in zahlreichen großtechnischen Anwendungen bewährt.
Stofftrennung durch Membranen
Authors: Rautenbach Robert , Albrecht Rainer
Published: December 2004

Separation by membranes. The paper reviews membrane processes in general, excluding the electro‐membrane processes. The authors' aim is to discuss the aspects common to all membrane processes as well as the essential differences between them. The following processes will be examined: Reverse osmosis, ultrafiltration, gas permeation through porous or diffusion type membranes, pervaporation and liquid membrane techniques. In liquid systems, mass transport at the membrane surface proves to be the limiting factor. Conditions on the permeate side tend to influence flux and quality of the permeate only when a considerable pressure drop occurs. A typical example is that of hollow‐fiber modules. It is shown how the permeability and dimensions of the membrane require selective adjustment in order to establish maximum flux.
Sauberes Wasser – technische Möglichkeiten, wirtschaftliche Konsequenzen
Authors: Lipphardt Günter
Published: December 2004

Clean water – technical possibilities and economic consequences. Water pollution by industrial effluent is becoming more and more of a political warcry which creates a fear of technology – precisely that technology which is largely responsible for the present quality of life. It has so far gone largely unrecognized by the public that industry and municipal authorities have accomplished a great amount in the area of waste water purification. The versatile techniques developed in recent years are summarized, and biological purification is treated in somewhat greater detail. Annual investment in waste water treatment runs at several thousand million DM, and represent a considerable financial burden on industry and municipal authorities. The thesis that economic considerations should play no role in environmental protection is not acceptable in that unqualified form, and would mean that German industry would no longer be competitive in an international arena. Ecological demands cannot be separated from economic considerations. All participants will have to make some compromises on our way to our desired goal of a flourishing economy in an almost intact environment.
Saubere Umwelt – eine gesellschaftliche Aufgabe
Authors: Feldhaus Gerhard
Published: December 2004

A clean environment – responsibility of society. The need for environmental protection was previously beyond question and is more so than ever today. Discussions or controversy centers on the extent of measures needed to protect our environment. Such discussion is conducted by pressure groups while decisions are made by society for environmental protection is a function of society. Whereas the aversion of danger was formerly the main consideration prevention is becoming increasingly important. The potential dangers have been essentially eliminated. It is our present task to ensure living space for future generations and to preserve space for tomorrow's industry. This is possible only with the aid of technology, provided that technologists are prepared to adopt new approaches. We must do away with a mere technology of reduction, i. e. peripheral environmental protection. Tomorrow's task is integrated invironmental protection.
Verfahrenstechnik der Kohlehydrierung in Sumpfphasen‐Reaktoren
Authors: Kürten Heribert
Published: December 2004

Chemical engineering of coal hydrogenation in sump phase reactors. The science of chemical engineering was still in its infancy when the hydrogenation of coal was developed from 1924 onwards at Ludwigshafen, Rhineland. The term backmixing, for example, was unknown. Nevertheless, the scale‐up from a pilot to a production reactor was performed correctly at that time. Even with today's knowledge, the IG Farben sump phase reactors could not have been better designed. Almost four decades have meanwhile elapsed since the cessation of coal hydrogenation in Germany (1945). Nowadays high pressure reactors having more than 50 times the volume of the IG reactors can be produced. Considerable advances have also been made in measurement and control engineering. Hence new chemical engineering questions and solutions arise. If coal hydrogenation is to be performed on a significant industrial scale in 10 to 20 years, this will be economically feasible only by exploiting the possibilities of large reactors having a throughput of 1 to 3 million tons of coal per annum.
Verfahrenstechnische Auslegungsunterlagen für Rührbehälter als Fermenter
Authors: Henzler Hans‐Jürgen
Published: December 2004

Engineering design data for agitator vessels as fermentors. The article develops and collects design data for stirring vessels for calculation of mass and heat transfer and the flooding point and stirrer power requirements for aerated liquids. The data refer to low‐viscosity, higher viscosity, and structure viscosity liquids with difering coalescence behaviour. The working data presented are used to derive results for a specific system (air/aqueous solution of carboxymethylcellulose) which illustrate decisive relationships and limitations arising from mass and heat transfer. There results important information for the operation, and choice, and scale‐up of stirred fermentors.
Auslegung und Maßstabsvergrößerung von Kristallisatoren
Authors: Mersmann Alfons
Published: December 2004

Design and scale‐up of crystallizers. Industrial scale crystallizers have to be designed in such a way that the crystalline product has the design particle size distribution, crystal form, and purity. Data on multiphase flow, solubility, balances of mass, energy, and number of crystals, kinetics (crystal growth rate and nucleation rate), and heat transfer are required. The present article discusses problems of kinetics in greater detail than other aspects. Multiphase flow is considered only briefly and heat transfer not at all. Familiarity with the terms homogeneous and heterogeneous (primary) and secondary nucleation [1, 2] is also assumed. This contribution is based on evaluation of available literature.
Rohrleitungstechnik und Verfahrenstechnik
Authors: Gelbe Horst
Published: December 2004

Pipework engineering and chemical engineering. Piping must be included as an essential part of a plant in the chemical engineering design of the process units. The necessary engineering specifications for an appropriate, minimum cost design of pipe systems and the job integration of pipe planning, which demonstrates the strong links between pipework engineering and chemical engineering in the planning and construction of plant, are discussed. The use of computers in pipe engineering began about 12 years ago. Development proceeded via computer mass listings, computer‐plotted isometric drawings, automatic material listings to the contemporary computed plotted flow charts, leading to increasing confrontation of chemical engineers with these programs with repercussions in their work. A report is presented on the development of new systems and on the present state of implementation of these computer methods; the scope and limitations are indicated.
Anlagentechnische Entwicklungen zur Erhöhung der Sicherheit
Authors: Friedel Lutz
Published: December 2004

Plant engineering developments for improvement of safety. Research undertaken in various companies for reliable dimensioning of production equipment to withstand dangerous pressure increases, e. g. as a result of a runaway reaction or a dust explosion, is presented. Measures for the safe removal of the reaction materials are discussed.
Fortschritte in der Zerstäubungstrocknungs‐Technologie
Authors: Hein Jean‐Claude , Rafflenbeul Rolf , Beckmann Manfred
Published: December 2004

Progress in the technology of spray drying. Stringent quality demands on spray‐dried goods have led to increasing use of nozzle spray dryers. In contrast to disk spray dryers, nozzle dryers yield microgranules and low‐dust products directly. Although the process of nozzle spray drying is over 50 years old, the volume of available calculation material necessary for general application is sparse and limited mainly to special products or problems. This article presents new advances in the technology of nozzle spray dryers. An analytical formulation of the drying of a drop within the first drying phase decisive for granulation constitutes the basis of the general applicability of the fresh insights gained.
Fertigungstechnische Probleme beim Einwalzen und Schweißen von Rohren in Rohrböden bei Wärmeaustauschern
Authors: Vollhardt Frohmut
Published: December 2004

Production problems in the rolling‐in and welding of tubes in the tube plates of heat exchangers. One of the principal problems besetting the construction of equipment is the mutual sealing of pressurized spaces. These sealing problems governed design for many years and remained virtually stagnant for decades. New chemical processes involving maximum thermal flux densities compelled engineers to produce new designs. Further problems were those of high and low‐temperature corrosion and attack by erosion which required mastering by design measures. The historical development of design constitutes the basis of the paper. The following topics are considered: (1) Rolling‐in and welding techniques; (2) automated welding in nuclear power plant construction (demands placed on seam tube/deposit welding; special demands on production techniques); (3) quality assurance (quality planning, quality control, checking measures, destructive testing, procedures adopted in case of deviations, quality analysis, documentation).
Werkstoff‐ und Schweißfragen bei der Herstellung von dickwandigen Druckbehältern für höhere Betriebstemperaturen aus Stählen mit 2 bis 3% Chrom und ca. 1% Molybdän
Authors: Grote Günter
Published: December 2004

Materials and welding in the production of thick‐walled pressure vessels for elevated operating temperature made of steels containing 2 to 3% of chromium and ca. 1% of molybdenum. High‐temperature steels containing 2 to 3% of chromium and ca. 1% of molybdenum are resistant to hydrogen under pressure at temperatures up to about 500°C. Being readily weldable, they are excellently suited for high pressure equipment in chemical plant construction. Their tendency to embrittlement at operating temperatures of 400 to 500°C is a drawback. However, specific metallurgical measures adopted during the production of the semifinished material and the welding materials, and use of optimized welding techniques and heat treatment keep this embrittlement within limits. The article reports recent experiences gained in producing pressure vessels with welding seam thicknesses of up to 230 mm at the authors company.
Die Grundlagen der pneumatischen Förderung
Authors: Wirth Karl‐Ernst
Published: December 2004

Principles of pneumatic conveying. The design of pneumatic conveying systems is critically dependent upon a knowledge of the pressure drop and the minimum necessary velocity of the conveying gas. Starting from the areas of application of pneumatic conveying systems, the conveying states occurring are discussed and appropriately assigned to the diagram of state. The pressure loss equation is reported for conveying in form of a fully suspended flow and strand‐type conveying and the theoretically predicted pressure losses are compared with experimental values for the conveying of coarse and finegrained materials. After mentioning the calculation of the pressure drops due to acceleration and to pipe bends, the article discusses the problem of pipe enlargement for long conveying distances. Equations are also given for the calculation of the so‐called blocking limit and of the conveying gas velocity at which the minimum pressure drop occurs. The influence of the compressor on the choice of the operating point is also discussed. New calculation equations are then given for horizontal and vertical conveying in form of a fully suspended flow conveying and for horizontal strandtype conveying which permit reliable scale‐up. Moreover, a new equation is reported for the blocking limit in horizontal conveying.
Kriterien zur Beurteilung der Zündgefahren infolge elektrostatisch aufgeladener Flüssigkeiten
Authors: Krämer Helmut
Published: December 2004

Criteria for the assessment of ignition hazards due to electrostatically charged liquids. The state of the art in the assessment of ignition hazards due to static electrification of liquids is reviewed. Starting from the physical problems of the electrification of streaming or sprayed liquids, the charge accumulation and resulting electrical fields and potentials as well as the question of incendivity of the different types of gas discharges occurring as a consequence of the highly charged liquid, the criteria are presented which allow the assessment of the ignition hazard in practically relevant cases such as tank filling with chargeable liquids, charging resulting from stirring processes and charging of liquid sprays during tank cleaning with liquid jets.
Verfahrenstechnische und wirtschaftliche Aspekte der Verarbeitung verdünnter SO2‐Gase zu Schwefelsäure
Authors: Sander Ulrich , Fattinger Volker
Published: December 2004

Chemical engineering and economic aspects of converting dilute SO2 gases into sulphuric acid. In the contact process for production of concentrated sulphuric acid the lowest limit for the autothermal processing of dilute SO2 gases lies at around 2 vol.‐% SO2 provided that a pre‐drying concentrating system is in use. Yet more dilute SO2 gases can be processed by Ciba Geigy's nitrogen oxide/sulphuric acid process – a modern version of the well‐known lead chamber process – which is already producing 70 to 75% H2SO4 from molybdenum disulfide roasting waste gases of ca. 1 vol.‐% SO2 on an industrial scale. The paper considers not only the specific boundary conditions, and chemical engineering characteristics of the two fundamentally different processes but considers above all the economics of processing low‐concentration SO2 gases for sulphuric acid.
Sieden — Stabilisator und Störfaktor sicheren Betriebes
Authors: Mayinger Franz
Published: December 2004

Boiling – stabilizer and destabilizer of safe operation. Boiling is used in power‐ and chemical engineering if large quantities of energy have to be transported and if high heat‐flux densities have to be applied. The stabilizing action of boiling, which is already high due to the large heat transfer coefficients and small temperature differences, is further improved by the fact that heat transfer still increases with increasing energy addition. Even if single‐phase liquid flow is present under normal operation conditions power fluctuations can be overcome without impermissible temperature rise due to the onset of subcooled boiling. Beyond a critical heat‐flux, however, film boiling starts which decreases the heat transfer coefficient by orders of magnitude. In apparatus in which the fluid is transported under conditions of high void fraction it should be ensured that the liquid film at the wall is thick enough to guarantee a sufficient heat transport. Also, under these conditions boiling can stabilize or destabilize the energy transport.
Aufgabengerechte Informationssammlung für die Verfahrensentwicklung
Authors: Blaß Eckhart
Published: December 2004

Information system for process development. An essential requirement for successful process development is the availability of relevant specialist information. Structuring the necessary activities by the techniques of systems engineering during the course of process development can provide detailed knowledge of the information required. However, comparison of available supply and demand shows that an essential part of the information, i.e. the solutions of unit operations and the accompanying equipment, have not hitherto been collected in systematic information systems. There fore principles are developed for the creation of information systems for process development and are demonstrated by the example of a „solution catalogue”︁ for filter equipments for the solid/fluid separation.
Neue Entwicklungen zur Druckwechsel‐Adsorption
Authors: Richter Ekkehard , Harder Klaus‐Burkhard , Knoblauch Karl , Jüntgen Harald
Published: December 2004

New developments in pressure swing adsorption. Continuing development of the adsorption agents and optimization of the process have permitted solution of new problems of selective separation and isolation of gases from gas mixtures and of gas purification by pressure swing adsorption. While processes have previously been developed in which the product gas is obtained during the adsorption step, more and more processes are now becoming available in which gases of high purity are obtained during the desorption step. After derivation of the fundamental desorption steps, the new techniques are illustrated in the case of the enrichment of CH4, CO2, and ozone, and for recovery of NOx from nitric acid waste gases.
Rauchgasreinigung mit trockenen Sorbentien – Möglichkeiten und Grenzen
Authors: Michele Helmut
Published: December 2004

Purification of flue gases by dry sorbents – possibilities and limits. The desired level of purification of the gases, even with smaller amounts of exhaust gases, requires technically straightforward methods. Purification of flue gases using socalled „dry”︁ methods offers the advantage that no problems associated with waste water arise. The gaseous impurities are deposited onto dry sorbents, which can subsequently be disposed of in the dry state. In the article the advantages and disadvantages of „dry”︁ methods are contrasted using examples from plant both at the planning stage and that already commissioned.
Alternative Transportsysteme für den Langstreckentransport in der Chemischen Industrie
Authors: Bahke Erich
Published: December 2004

Alternative transport systems for long‐distance transport in the chemical industry. The survival of a company in the chemical industry is nowadays determined by the location of raw materials and the transportation routes and transfer centres to the chemical production sites, and particularly also on the availability of economical and environmentally unobjectionable transport systems and procedures. Increasing difficulties and legislation in the chemical industry, especially due to environmental and disposal problems, as well as the increasing density of mass flow thanks to increasing productivity, demand new technologies and alternative transport systems which can be integrated into a network of modern and environmentally appropriate conveying and storage systems. In a framework of increasing automation of all transport, pipeline transport will become increasingly attractive to the chemical industry with increasing environmental consciousness. Even though not all products can be transported through pipes, such materials can still be transported in „pipeline‐like”︁ manner, i.e. continuously in closed systems.
Siebklassieren
Authors: Schmidt Paul
Published: December 2004

Sizing by sifting with screens. Viewed physically, screening comprises superposition of segregation, diffusion, and passage through the screen. Frictional and cohesive forces have to be overcome and the coarse feed material transported over the screen, primarlily by circular, elliptical, or linear vibration. The specific screening performance and the sharpness of separation prove to be a measure for the quality of screening. There are three uses for screening: protective screening with mean particle size Dm ≪ mesh w with a simultaneous wish for high screen performance; classification with Dm ≈ w with a desire for greater sharpness of separation; and dust removal with Dm ≫ w and the problem of deagglomeration, i. e. separation of fines from the screened material. The maximum screen performance can be calculated for the coarse range; it is attainable with most screening machines. A problem encountered in the medium to fine size range is prevention of blinding of the screening machine and deagglomeration of sieved material, with attrition phenomena deserving attention. A range of machines is available: casting, planar, tumble, agitator screening machines are available, as are those with deforming screens, those utilizing centrifugal forces, and, as the latest addition, flow screening. New developments concentrate on fine screening, e. g. screening machines with direct activation of the screen fabric, tumble screening machines, combinations of mechanical and pneumatic screening extending through to pure flow screening. Plastic screens made of polyurethane are of advantage for wet screening; they exhibit greatly reduced wear. Safety requirements are met by silenced and explosion‐proof‐screening machines.
Industrielle Anwendung zeolithischer Katalysatoren bei petrochemischen Prozessen
Authors: Hölderich Wolfgang , Gallei Ewald
Published: December 2004

Industrial use of zeolites in petrochemical processes. The cost rise of feedstock triggered by the energy crises as well as increased environmental awareness have accelerated the development of new, environmentally more acceptable processes and the introduction of improved catalysts in the petrochemical industry. In this regard, zeolites have an important contribution to make as catalysts. The utilisation of zeolites in large‐scale technical operations in crude oil processing and petrochemistry is reviewed and the advantages of these catalysts and their influence upon process design are presented. Hydrocracking, dewaxing, methanol‐to‐gasoline (MTG), the Mobil‐Badger process and xylene isomerisation are discussed. A description of the conversion of methanol to olefins indicates that zeolite catalysts will continue to be of great interest in chemistry.
Die Schmelzkristallisation von organischen Stoffen und ihre großtechnische Anwendung
Authors: Rittner Siegbert , Steiner Rudolf
Published: December 2004

Melt crystallization of organic substances and its large scale application. In the separation and purification of organic substances, water‐ and solvent free melt crystallization is gaining importance as an independent thermal unit operation. This contribution reviews the physico‐chemical fundamentals, the various process fundamentals, large scale application examples and advantageous possibilities of combination of melt crystallization with other separation processes. A consideration of advantages and disadvantages of this particular separation process should indicate possibilities for new fields of application.
Wiederaufarbeitung von Kernbrennstoffen
Authors: Mischke Joachim
Published: December 2004

Reprocessing of spent nuclear fuels. The present waste disposal concept for nuclear power plant requires the rapid construction of a reprocessing plant in the Federal Republic of Germany, with the location still being uncertain (Bavaria or Lower Saxony). The task of such a plant will consist in recovering usable nuclear fuels and processing them to new fuel elements. Waste materials are prepared for final disposal. The components of the plant are presented with their design data, associated development plans are discussed, and changes with respect to former plans, in particular the maintenance concept, are outlined. The article also reports the present status of the licensing procedure and current planning.
Pervaporation und Gaspermeation — Grundlagen der Prozeßentwicklung
Authors: Rautenbach Robert , Albrecht Rainer
Published: December 2004

Pervaporation and gas permeation – fundamentals of process development. Non‐porous membranes represent the basis of reverse osmosis, of pervaporation, and also of gas permeation. In each case, economic viability was achieved only when it proved possible to use this kind of membrane in its asymmetric form in each of the processes concerned. Starting from the mass transfer in the membrane, the influence of each of the following points on plant design for pervaporation and gas permeation is discussed: 1. asymmetry of the membranes; 2. concentration polarization; 3. flow in the module; 4. the pressure drop; and 5. the heat transfer problem (exists only for pervaporation). In connection with the flow in the modules, the economics of series of membranes and membrane columns are compared. In conclusion, a number of applications are discussed which demonstrate where economically sound uses of the two processes are to be found.
Leitsysteme für Produktion und Labor „Stärken und Schwächen der heutigen Hardware und Software, Entwicklungstrends und Zukunftsaussichten
Authors: Best Roland
Published: December 2004

Control systems for production and laboratory. Strengths and weaknesses of contemporary hardware and software, developmental trends and future prospects. The state of the art of control systems in production and laboratory is considered with the aid of some representative examples. The strengths and weaknesses of available control systems are discussed. It is shown that further rationalization in production can only be achieved when the interchange of information between the control layers of production is improved. Also open to considerable improvement is the flow of information in the laboratory and the cross‐flow between laboratory and production. The present development of microelectronics (microprocessors, personal computers, data busses, local area networks (LAN)) will greatly change process control technology.
Dosieren von festen und fluiden Stoffen
Authors: Vetter Gerhard
Published: December 2004

Dosage of solids and liquids. Dosage of reaction components is an important step in chemical engineering processes. In an age of increasing automation, the development of dosage procedures is highly topical; electronics and data processing have long made inroads into dosage procedures. However, today's more stringent demands with regard to pressure, temperature, viscosity, and abrasion necessitate intensified research and development efforts. The present article considers mainly volumetric and geometric dosage methods. The many types of metering pumps cover a large area of dosage of liquids. Minimal flow rates, pressures up to several 1000 bar, and also dangerous and difficult fluids can all be safely handled. Leakproof designs with membranes, tubes, or bellows as displacement devices are particularly important nowadays. Volumetric dosage of solids requires establishment of a reproducible packing density. The survey considers the principle methods of dosage (also against pressure) with special emphasis on screw dosage. Gravimetric dosage methods are extremely reliable and accurate but generally require volumetric systems for energy supply. Especially when used in combination with metering pumps or screw dosage, differential balances have numerous possible applications.
Verfahren zur Minderung von NOx‐Emissionen in Rauchgasen
Authors: Schrod Manfred , Semel Joachim , Steiner Rudolf
Published: December 2004

Processes for lowering NOx emissions in flue gases. The authors survey processes currently under development for reducing NOx emission levels of combustion units. Primary measures, i.e. acting upon the combustion process itself, do not suffice to meet the recently stiffened limiting emission values; particular attention is therefore paid to secondary measures involving the flue gases. The article describes both wet processes and dry catalytic and non‐catalytic processes, some of which can also be employed for simultaneous removal of NOx and SO2. In view of the fast large‐scale implementation demanded, only a few, already extensively developed processes will presumable be accepted, and will play a considerable role on an industrial scale.
Mikrofiltration von Fermenterbrühen
Authors: Rähse Wilfried , Carduck Franz‐Josef
Published: December 2004

Microfiltration of fermentation broths. Crossflow microfiltration is a modern process for the work‐up of fermentation broths. In the case of intracellular components, the cells can be enriched by this technique prior to disintegration of the cells. Extracellular products can be separated from the cells by the microfiltration membrane, and also from solids originating from the nutrient. The approach adopted in isolation of dissolved products by crossflow microfiltration is illustrated for alkaline protease, particular attention being directed to the dependence of the flow of permeate and the retention of the membrane material, the mean pore size of the membrane, the operating conditions, the physical data of the fermentation broth, and the addition of solids, which are discussed and quantified.
Aufstellung von Sicherheitsanalysen durch die Betreiber chemischer Anlagen
Authors: Hezel Carl
Published: December 2004

Safety analyses conducted by companies operating chemical plant. The problems with safety analyses have shifted from existing plants to analyses for plants which are subject to an approval procedure. The latter require more effort and cause additional problems although legislation requirements are identical for both types. At BASF safety analyses are carried out by a group of experts responsible for design and operation of the respective plant. The authorities of the State of Rheinland‐Pfalz have formed a team to examine these analyses statewide. Difficulties still exist in presenting every possible hazard source and sequence of failure steps and in quantifying the effects of a hypothetical breakdown. However, one can generally state that the companies have learnt to satisfactorily carry out the extensive documentation task required by law.
Aktuelle Entwicklungen auf dem Gebiet der Reinigung und Desinfektion in der Lebensmittel‐Industrie
Authors: Loncin Marcel
Published: December 2004

Recent developments in cleaning and disinfection in the food industry. Dirt consists of residues of food which adhere to the equipment, of deposits which have a composition different from the product itself, or of microorganisms grown on solid surfaces. Fouling depends primarily on the nature of the food processed, but is also strongly influenced by the design of equipment, by the magnitude of shear forces, and possibly by the use of solid particles to prevent adhesion in suspension or fluidized beds. Cleaning implies efficient mechanical action (pumping or spraying) and the use of a detergent. Caustic and mineral acids plus surface active agents are always preferred. In this case the disinfection itself is no problem and can be completed by rinsing with chlorinated water. A method is presented which allows determination of the sometimes unexpected influence of bacterial residues on the shelf life of foods. Some recommendations for cleaning and disinfection in biotechnology are also formulated.