bluuebunny/crossref_metadata_2025 huggingface dataset:
Die diskontinuierliche Zentrifuge als Betriebssystem in der Chemischen Industrie
Authors: Simon Eberhard
Published: December 2004

Discontinuous centrifuges as operating systems in the chemical industry. Centrifuges are machines with rotors as working spaces in which the relative concentrations in mixtures of substances can be modified. Batch operating centrifuges are particularly suitable for this purpose when high demand on quality are made with regard to separation and purity of the substances separated or when the material parameters are subject to variation. The construction permits optimum adaptation to all operating parameters. The structural components for basic and additional functions have achieved a high standard of technical maturity and some have be specified in proven DIN standards. Centrifuges are particularly suitable for use as components of combined mechanical‐thermal demoisturing plants. The technology of the drive systems of centrifuges and the control systems for conducting the process and for safety purposes utilize advanced hydraulics, pneumatics and electronics. Numerous materials of construction are available, including highly corrosion‐resistant metals and alloys and those bearing a corrosion‐resistant protective layer. The choice and utilization of a particular structural form are determined by the specific operational behaviour on filling, washing of the filter cake residual moisture content attainable, output of solids, demoisturizing capacity, industrial hygiene aspects of sealing during demoisturization and on output, optimum arrangement of the centrifuge in the overall plant, as well as costs of acquisition, installation and operation. Safety features are of particular importance in view of the large amount of energy stored and the possibility of operating with flammable liquids. On the basis of systematic analyses of the sources of danger, constructive measures and systems have been developed for the avoidance of explosion and fire which ensure safe operation of centrifuges.
Meßmethoden in Fermentern unter sterilen Bedingungen
Authors: Onken Ulfert , Buchholz Rainer
Published: December 2004

Measuring methods for fermentations under sterile conditions. In process development as well as in industrial production it is necessary to obtain information about the state of the process by the measurement of characteristic variables. This is true for bioengineering in the same way as for chemical processes in general. Characteristic variables to be taken into consideration include temperature, pressure, masses and mass‐flow rates, operating parameters such as liquid level and impeller speed, and especially the concentrations of reactants, intermediates, and products. In contrast to other processes, a particular problem exists in fermentation because introduction of microorganisms, into the system by the measurement has to be prevented. Since taking samples from the reactor is hardly suitable for controlling the process for various reasons (amount of work, loss of time), this review considers only those methods which can be used for measurements directly in the fermentor. Essentially these are physical and physico‐chemical methods, e. g. for concentrations (O2 and CO2 in gas and liquid phase, pH, biomass). Of special interest for future development are spectroscopic and enzymatic methods for fast determination of substrates and of important intermediates and products. Here the sterility required entails special problems in the case of enzyme electrodes. Important information on the state of the process can, of course, also be obtained from physical variables, such as gas hold‐up, bubble size, viscosity, and turbulence properties of the medium. These variables are less critical with regard to sterility.
Die Wirbelschicht in der Feuerungstechnik — Stand und Aussichten
Authors: Schilling Hans‐Dieter
Published: December 2004

Fluidized‐bed firing technology – State of the art and prospects. After categorizing fluidized‐bed combustion according to process engineering criteria, the following features are then discussed on the basis of R & D results and of experience gained with demonstration units over the past four years: the range of feed coal qualities, combustion intensity, cleanness (SO2, NOx, CO, halogen, dust, disposal properties, and usability of residues), flexibility for partial load operation, and availability. The system‐inherent possibilities could be exploited to such an extent that initial commercial application is within reach. Furthermore, significant improvements seem to be possible. The intial results obtained with binding of fluorine are to be regarded as positive, large‐scale feasibility, however, still needs to be proven. Economic criteria are dealt with. The state of technology worldwide is discussed as well as modified experimental plants and facilities. Possibilities of further development are pointed out.
Einsatzmöglichkeiten drehzahlregelbarer Drehstromantriebe in der chemischen Industrie
Authors: Nachtkamp Jürgen
Published: December 2004

Applications of variable speed three‐phase motors in the chemical industry. For good reasons, three‐phase motors are used very widely in the chemical industry. Their considerable operation advantages have formerly been offset by the drawback of an invariant speed. Since the use of variable‐speed three phase motors (with transistor and thyristor technology) has become economical in various applications, new opportunities are opening up for chemical engineering. In order to demonstrate the wide application of this new technology, the article first surveys the electric motors used in a large chemical plant. The two principal motivations for using variable speed three‐phase motors are then considered, viz. energy saving and chemical engineering improvements, and the attainable advantages are set out against the technical and economical limitations on use. In conclusion, the risk of breakdown of variable speed three‐phase motors is discussed in relation to conventional technology.
Die Struktur turbulenter Freistrahl‐Diffusionsflammen
Authors: Peters Norbert
Published: December 2004

The structure of turbulent jet diffusion flames. This review considers recent developments in the description of kinetic effects in turbulent jet diffusion flames without swirl. The model of laminar flamelets is introduced, which allows description of effects far from chemical equilibrium – for instance local quenching phenomena. A similar solution is given for the equations governing round jet flames. Finally, relations for the mean chemical reaction rate and the formation rate of NO are derived. The article concludes by mentioning recent investigations on flame stability.
Nichteisenmetalle im Apparate‐ und Anlagenbau
Authors: Köcher Reiner
Published: December 2004

Non‐ferrous metals in construction of equipment and plant. The use of copper, copper/nickel alloys, highly corrosion resistant NiMo alloys, titanium, zirconium, and tantalum is described with the aid of examples. Brief mention is also made of the corrosion‐resistance of the above materials of construction. It is shown that a plate design of pressure vessels has economic and technical advantages over a solid design. Properties and working of plated composite materials are considered. An account of the lining of large‐scale chemical reactors with copper‐plated sheets is also provided with actual examples. The quality of production of tube mountings is described in the case of titanium heat exchangers, paying particular attention to drift attrition behaviour, reduction of wall thickness, and tube welding procedures. Tube fixing in heat exchangers made of NiMo28 is briefly mentioned.
Ermittlung sicherheitstechnischer Kenngrößen explosionsfähiger Gasgemische
Authors: Hofmann Hanns , Schmidt Gerhard
Published: December 2004

Determination of safety characteristics for explosive gas mixtures. This paper presents equipment for determining safety characteristics such as explosion limits, flame temperatures, and laminar flame velocities. Contactless methods of measurement such as infrared thermography, interferometry, and Laser‐Doppler anemometry are of particular importance. By means of selected gas mixtures it is shown that the composition of the gas mixture, the initial temperature and, as far as explosion limits are concerned, also the type of ignition source are important parameters. Finally, the influence of additives is reported which even in relatively small quantities strongly modify the whole combustion process and are therefore also relevant in safety problems.
Neue konstruktive und prozeßtechnische Konzepte für die Wasserstoff‐Gewinnung durch Elektrolyse
Authors: Wendt Hartmut
Published: December 2004

New design and process engineering concepts for production of hydrogen by electrolysis. Electrolytic production of hydrogen has attracted particular interest in connection with expansion of nuclear generating capacity in France, Belgium, Canada, and Japan as a means of balancing load, and for developing countries with hitherto untapped hydroenergy resources it provides a means of supplying fertilizers with any need for oil imports. However, the present state of the art of water electrolysis leads to excessively high production costs owing to excessively high investment costs and to high an energy consumption, far above the thermodynamically calculated energy requirements: reduction of production costs will require satisfaction of opposing demands for raising the space‐time yield of electrolyzers by increased current density while simultaneously lowering the energy consumption by reducing the cell potential. This contribution describes measures intended to save 20 to 30% in energy requirements; the production costs will fall by about 20 to 25%.
Einsatzbereich des Werkstoffes Glas in der Anlagentechnik
Authors: Pilhofer Theo
Published: December 2004

Scope of glass as material of construction in plant engineering. In conjunction with PTFE as sealing material, borosilicate glass is nowadays recognized as a material for plant construction. A complete modular system of individual components with suitable connecting pieces is available. Moreover, a variety of equipment has been developed for accomplishing various processes while paying due attention to the special material properties of the material glass. In combination with other materials, primarily in the field of heat exchangers and evaporators, numerous processes are now conducted without any difficulty in glass plant. In this range of processes, a special place is assumed by those which urgently require glass for corrosion reasons, such as chlorination or bromination reactions or concentration of acids, because specialized know‐how is sometimes required.
Maßnahmen zur Intensivierung des Wärmeübergangs
Authors: Stephan Karl , Mitrović; Jovan
Published: December 2004

Measures for intensifying heat transfer. Various approaches to the intensification of heat transfer have occupied engineers for many years. Many proposals failed to be accepted while others have been adopted in practice and have led to considerable savings in energy and materials. This article considers a number of topical developments in the improvement of convective heat transfer, heat transfer on evaporation, and heat transfer on condensation. The authors cite primarily review articles from among the extensive body of literature pertaining to this field of study.
Trägerbiologien in der Abwassertechnik
Authors: Oehme Christian
Published: December 2004

Support biologies in waste water technology. The numerous possibilities of immobilizing biomass and using it fixed on a wide range of carriers in the available types of reactors is matched by a great variety of practical applications in waste water purification technology for partial, complete, subsequent, and ultrapurification. All support biologies share the following advantages to a greater or lesser extent: smaller reactor volumes and shorter reaction times thanks to higher biomass concentrations; volume reduction or elimination of subsequent purification pools owing to the more favourable sludge index and fixation in the reactor or the filter; long sludge lifetimes are possible (favourable for slowly multiplying nitrifiers and specialist strains); no floating sludge formation on carbohydrate degradation or nitrification; increase in process stability and degradation activity towards refractory compounds which are difficult to degrade biologically if suitable supports showing synergistic activity are used, such as highly porous activated charcoal.
Systeme zum Ein‐ oder Austrag von Schüttgütern in oder aus Druckräumen
Authors: Stahl Werner , Stadler Reinhold
Published: December 2004

Systems for the charging or discharging of bulk solids into or out of pressure chambers. In many branches of chemical and dressing technology there are compelling thermodynamic or economic reasons for carrying out various processes at pressures deviating from ambient values. If the reactants and products of these processes are dusts or granular solids then numerous problems are encountered on transfer between regions of higher or lower pressure. On the one hand, the properties of the feed (such as particle size, flow behaviour) should undergo the slightest possible modification, and on the other hand the transport of the material between the regions of differing pressure should be as continuous as possible. Moreover, the gas transport should be kept low. Pressure swing in the process region is to be avoided. The aim of this study was to survey all systems suitable for introduction or removal of bulk solids into or out of chambers at pressures other than the ambient value. The various pressure locks are assessed qualitatively for given tasks. A new solution is presented for the discharge of filter cake from high‐pressure chambers.
Informationshaushalte in Labor und Produktion
Authors: Peters Rolf Wolfgang
Published: December 2004

Information management in laboratory and production. The competitive situation is compelling companies to reduce production costs, to improve product quality, and to react very fast to changing market requirements of product properties. Apart from these necessities, the material flow itself needs to be optimized with the aim of reducing stockpiles of raw materials and of intermediate and finished products without sacrificing flexibility and ability to fulfill orders. These demands can only be met when the informations accompanying the production process have been mastered. An overview of all data accruing in the areas of production and the laboratory is essential. Together these data represent the information flow of laboratory and production plant. Modern semiconductor technology permits cost‐saving construction of powerful information systems which have meanwhile become an essential competitive factor. This article attempts to provide an introduction to phase and layer models, and thus to offer structuring aids.
Mensch‐Prozeß‐Kommunikation
Authors: Färber Georg , Polke Martin , Steusloff Hartwig
Published: December 2004

Man‐process communication. Computers are extensively used to control technical processes, but man is still irreplacable as observer and decision maker. The paper gives an overview of the channels existing between man and process. These channels have to deliver as much information as necessary, but as little as possible to allow the right decisions. Good models, concerning the production process and its individual phases, the structure of the control system, and the behaviour of man are required to extract the relevant information out of a large amount of data. Methods of signal processing and pattern recognition help to reduce the dimensionality of the active state vector allowing the control system to provide „information”︁ instead of a collection of „signals”︁. The paper also describes the state and future development of important technological aspects, e. g. interactive display systems and real time data base systems.
Mischen in Schneckenmaschinen, Teil 2: Suspendieren, Desagglomerieren und Emulgieren
Authors: Pahl Manfred H.
Published: December 2004

Mixing in screw mixers, Part 2: Suspension, de‐agglomeration, and emulsification. This paper explains the physical laws pertaining to the suspension of solids in liquids, to deagglomeration, and to mixing of immiscible liquids; some results from these different fields are also presented. In fibre reinfored plastics the length of the fibres must be great and the distribution of their length must be narrow. The product undergoes little grinding on using mixing with low shear stresses, feeding with fibres that are not too long, and adding the fibres to the melt. Pigments and some other additional materials tend to agglomerate. De‐agglomeration is necessary to improve the products. It is determined by the adhesion and the force number, which is the product of velocity and time of shearing. Taking suitable action will ensure minimized abrasion in case of abrasive material. A size distribution of droplets will be found if there is only a limited miscibility of liquids. Only size reduction will improve the homogeneity. The velocity of shearing, the interfacial tension, and the ratio of the viscosity of the components, all play a role in this process.
Auswahl und Betrieb von Brüdenverdichtern in chemischen Produktionsanlagen
Authors: Mangartz Karl‐Heinz , Handl Roland
Published: December 2004

Choice and operation of vapour compressors in chemical production plant. The use of vapour compressors for evaporation, distillation processes and also for more complex processes has increased greatly due to the large increases in energy costs in the past. Generally, high speed radial compressors are used for these applications. Recommended operating ranges, investment costs as well as efficiencies at different compression ratios are explained, based on experience gained in technical application and manufacturers information. The example of combining a separation column and an evaporation step shows that not only a saving of energy, but also a significant reduction of waste water generation is achieved. The control strategy for a process having several recycle flow streams is explained. Based on operating experience, recommendations for field monitoring of the compressor are given.
Blasensälen — Erkenntnisstand und Entwicklungstendenzen
Authors: Deckwer Wolf‐Dieter , Schumpe Adrian
Published: December 2004

Bubble columns – present knowledge and future trends. Considering the abundance of phenomenological and empirical studies on bubble columns, future research and development should place greater emphasis on theory. This paper therefore reports on suggested theoretical concept, new hydrodynamic models, and results of turbulence theory, and considers their potential influence on the development of new reactor models for bubble column reactors.
Verwendung von Kohlendioxid bei technischorganischen Synthesen
Authors: Behr Arno
Published: December 2004

Use of carbon dioxide in industrial organic syntheses. Although carbon dioxide is important as an abundant carbonaceous raw material, its utilization in chemical processes so far has been rather limited. This review covers the reactions of CO2 employed in industry, such as the production of urea, the Kolbe‐Schmitt reaction, the synthesis of cyclic organic carbonates, and the use of CO2 in methanol synthesis. Interesting recent developments in CO2 chemistry, especially the transition metal catalyzed reactions, are also elucidated. In addition to the synthesis of polymers and hydrocarbons, the production of oxygen‐containing chemicals seems to be very profitable and attractive for future industrial applications. Not only can derivatives of formic acid and carbonic acid be formed but longer‐chain carboxylic acids and their derivatives are also accessible by reactions of carbon dioxide with hydrocarbons such as alkynes, alkenes, and 1,3‐dienes.
Packungskolonnen
Authors: Mersmann Alfons , Deixler Alfred
Published: December 2004

Packed columns. Packed towers with dumped or regular packings are widely used in industry for accomplishing chemical engineering processes. Packed columns are able to work economically even under extreme process conditions (e. g. vacuum, high temperature, aggressive flow mediums), because of the available variety of packing types and the straight‐forward manufacture of the individual packing elements from almost any material. The present contribution shows the different kinds of packings arranged according to their geometry and physical properties. A packed tower for gas/liquid countercurrent operation is shown as a basic construction with the necessary internals. Since packed columns are mostly used in gas/liquid countercurrent operation, the fundamentals of fluid dynamics and mass transfer are presented for this operating condition.
Die elektrochemische Fluorierung – ein Überblick
Authors: Hollitzer Enno , Sartori Peter
Published: December 2004

Electrochemical fluorination – a review. The versatile method of electrolysis in hydrogen fluoride solution or suspension is reviewed. An attempt is made to give separate definitions for the different methods of electrochemical fluorination. In addition a supplement, containing tables of all papers and patents published in the past ten years is available.

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Stand und Entwicklung der kontinuierlichen gravimetrischen Dosierung von festen und flüssigen Stoffen
Authors: Gericke Hermann
Published: December 2004

State of the art in continuous feeding of solids and liquids. After defining the characteristics of continuous gravimetric feeding systems, the author lists the aims and reasons for the application of these methods in one‐ and multiple component systems. We can distinguish between gravimetric feeders with positive gross weighing and negative net weighing. The latter principle has advantages in operation, and is embodied in the weight‐loss weigh feeders. A synoptic chart of the various gravimetric feeder designs shows the nature and the method of acquisition of the controlled value and also classifies the fields of application as to feed range and material characteristics. When designing a feeder, the weight and volume of material flow, the characteristics of the weight resolver and of the metering device have to be considered. Latest developments of the principal components of weigh feeders are illustrated by examples, such as metering devices for solids with poor flow properties, combination of feeding and pneumatic conveying systems, headload compensation with weight‐loss weigh feeders, feeding with high instantaneous accuracy, gravimetric feeding of liquids at small feed rates, set point and ramp programming, and monitoring of the bulk density of the material.
Korrosion und Korrosionsschutz in Systemen mit neuen Energieträgern und Brennstoffen
Authors: Heitz Ewald
Published: December 2004

Corrosion and corrosion protection in systems utilizing new energy sources and fuels. New energy carriers such as methanol, ethanol, hydrogen, and biogas are of increasing interest for the substitution of the fossil fuels oil, natural gas, and coal. The analysis of production, handling, and use of such energy carriers with regard to materials and corrosion protection technology gives various results. Some of the problems can be solved by conventional technologies (production of ethanol and biogas). For others, further development work is needed (production of methanol; methanol and ethanol as substitute motor fuels). The problems encountered within the framework of a hydrogen energy technology are known and can be solved for the handling of hydrogen but they are still unsolved for special production processes (hybrid processes with sulfuric acid).
Rechnergestütztes Experimentieren in der chemischen Reaktionstechnik
Authors: Hofmann Hanns
Published: December 2004

Computer‐aided experiments in chemical reaction engineering. In recent years, relatively inexpensive microcomputers have become available which are very suitable for data acquisition, data storage, data handling, and for control and experimental design of laboratory reactors in reaction engineering. Various experimental set‐ups (integral, gradientless, and pulse reactors) as built in the Institute for Technical Chemistry I of Erlangen‐Nürnberg University are presented, their advantages and remaining problems discussed, and some results on kinetic analysis and reaction modelling reported.
Reinigung von Apparaten und Rohrleitungen
Authors: Sangen Mathias , Sckuhr Peter
Published: December 2004

Cleaning of equipment and piping. There has been an increase in the study of the causes of contamination and its appearance in equipment and piping. The increasing demands placed on the cleanliness of production plant for pharmaceutical and biochemical products has enhanced interest in industrial cleaning methods. Precisely this area will increase in importance in the future because this is where preventative measures and automation of cleaning will obviate the need for – frequently unpleasant – cleaning operations and at the same time effectively increase the capacity of a given plant.
Ziele und Methoden der elektrochemischen Verfahrens‐ und Reaktionstechnik
Authors: Wendt Hartmut
Published: December 2004

Objectives and methods of electrochemical process and reaction engineering. Electrolysis processes are distinguished from „normal”︁ chemical processes in several respects: (1) The electrical energy consumed is expensive and assumed the role of an expensive raw material. (2) Mass transfer in electrolytes is sluggish and limits space time yield to relative low values. (3) The rate of reaction is dictated by the applied electrode potential and this determines the cell voltage and energy efficiency of electrolysis processes. Effective electrocatalysts diminish energy consumption per unit mass of product. (4) The relatively poor electrical conductivity of electrolytes leads to construction of special closely spaced cells with narrow cell gaps. It is important to select the operation conditions of, e. g. organo‐electrosyntheses to minimise the efforts involved in isolation and purification of the product.
Einsatz von programmierbaren Taschenrechnern für verfahrenstechnische Berechnungen
Authors: Hüning Werner , Brunberg Raimund
Published: December 2004

Using of programmable pocket‐calculators for process engineering calculations. Part of a chemical engineer's daily work are repeated calculations to illustrate special relations. Suitable for this purpose are programmable pocket computers, which allow easy and quick programming by the user. This contribution gives brief instructions for creation of short and more complex programs in addition to those found in the user's manual. Independently of calculator type and nature of the problem, the single steps required to get a complete program are described. Using a special example from chemical engineering, the optimal pathway from the algorithm to the program listing is shown for two calculator types.
Technologien zur Sanierung von Bodenkontaminationen und Altlasten
Authors: Deckwer Wolf‐Dieter , Weppen Peter
Published: December 2004

Technologies for the clean‐up of soil contamination and older burdens. Older burdens as a consequence of fast industrialization and soil contamination by leakage and accidents require fast clean‐up. Sealing measures and storage on disposal sites postpone solution of the problem to some day in the future. Thermal treatment and washing entail extensive earth‐moving operations. They have a high energy requirement and are expensive. Microbiological processes presently under development are expected to yield less expensive solutions. The degradation properties of soil microflora or specially cultured microorganisms are exploited for this purpose. Treatment of lower‐lying contamination requires an adequate oxygen supply at the site of action.
Verfahren zur Mikrofiltration von Prozeßlösungen und ihre Anwendungen
Authors: Ripperger Siegfried
Published: December 2004

Approaches to microfiltration of process solutions and its application. Particles and microorganisms in the site range of 0.02 to 10 μm are reliably removed by microfiltration processes. Microporous polymer membranes are suitable as filter medium. The particles are then separated mainly on the exterior surface (surface filtration). This leads to formation of a covering layer on the membrane and a relatively high hydraulic resistance. Dynamic filtration processes counteract covering layer formation. The most widely developed technique is crossflow microfiltration, in which the membrane is subject to continuous flow of the suspension. The development of large membrane units fulfils requirements for large‐scale industrial application of crossflow microfiltration.
CAE in der Prozeßleittechnik
Authors: Geibig Karl‐Friedrich
Published: December 2004

CAE in process control engineering. The design and operation of chemical engineering plant involves collaboration of various specialist departments over a long period in an iterative sequence of steps. Any change in data in any of the necessary iterative steps can generate expensive errors. The aim of computer application and computerized development is thus basically to improve the integration of the various applications. Technical data processing, especially the use of CAD/CAE systems, therefore provides a framework for a whole group of measures intended to provide tools for mediumterm automatic handling of data and re‐use of partial solutions in memory.
Abscheidung von Feinstaub aus Gasen
Authors: Löffler Friedrich
Published: December 2004

Extraction of fine dust from gases. The main focus of interest and of problems in the area of particle extraction from gases has been shifting more and more towards fine dusts, i.e. dusts with considerable fractions below 10 ßm, sometimes far below 1 ßm. Solution of extraction problems in this range either requires new processes, of which there are not many, or, on use of conventional extractors, calls for modified engineering concepts and modes of operation. This survey first describes some typical sources of fine dusts and then considers various procedures for their extraction.
Spezielle Korrosionsschutz‐Maßnahmen im Chemie‐Apparatebau
Authors: Kuron Dieter , Gräfen Hubert
Published: December 2004

Special corrosion protection measures in fabrication of chemical equipment. An essential pre‐condition for uninterrupted and safe operation of equipment is a proper selection of materials with regard to service conditions, design, and fabrication. In case of difficulties with the application of unprotected metallic materials suitable additional measures must be applied to ensure proper performance of the equipment. Basically, there are four types of measures. The material can be improved by modification of the composition or fabrication (e. g. powder metallurgical, remelt techniques, accurate welding); the material can be protected by the application of a duplex‐system (lining, cladding, plating); the electrochemical performance of the metal can be influenced by superimposed currents (cathodic/ anodic protection); and last but not least a change in service conditions can meet the requirements for materials performance. To ensure satisfactory performance of protective measures, supervision of application, installation, and in‐service behaviour is a must.
Simulation in der Prozeßleittechnik
Authors: Kreitner Hermann , Schuler Hans
Published: December 2004

Simulation in process control. Distributed control systems provide their users with many potential benefits which are exhaustively used only in a small number of applications. Distributed control systems supply process data in real time in a digital format. When processing these data together with process models, the advantages of distributed control systems can be considerably extended. Process models are understood as mathematical systems containing a‐priori knowledge about processes in a numerical or logical form. In the context of distributed control systems, some new and exciting applications of modelling and simulation techniques become accessible. Basic concepts of these specific techniques are described in this contribution. A collection of potential and realized applications show that these methods allow for a more detailed observation and for advanced process control strategies.
Korrosionserscheinungen in strömenden Medien am Beispiel von Chemiepumpen
Authors: Tischner Hermann
Published: December 2004

Corrosion phenomena in flowing media, illustrated for chemical pumps. It is shown how centrifugal pumps in chemical plant are exposed to a complex superposition of (static and dynamic) mechanical and thermal stresses, of corrosion, erosion/abrasion and cavitation. Then examples of pump parts that have been operated under service conditions are shown to demonstrate appearance and origin of flow‐induced, erosion‐ and cavitation‐corrosion. Materials concepts are discussed that are able to avoid or reduce these phenomena. Several pump‐like test methods are introduced that permit selection of pump materials in accordance with the practical service conditions, where hydraulic, design, and materials criteria have to be optimized to guarantee long pump lives.
Apparate aus Sonderwerkstoffen
Authors: Donat Helmut
Published: December 2004

Equipment made of special materials. Errors in the planning phase of capital expenditure and major repairs often lead to particularly high costs in remedying them. The investigations that were necessary to ensure reliable manufacture are described with reference to a heat exchanger made of zirconium. In addition to design details, the testing of the explosiveclad tube sheets and the welding of the heat exchanger tubes are explained at length. In the repair sector a report is given on damage to an evaporating vessel made of nickel‐clad sheet. Particular attention is paid to the build‐up of tension in the cladding in relation to the support material. A second example of damage is used to show the influence of design details on the damage mechanism. In this case Monel 400 piping is involved.
Wärmeübertragung zwischen einer Wand und dispersen Gas/Feststoff‐Systemen
Authors: Tsotsas Evangelos , Martin Holger
Published: December 2004

Heat transfer from a rigid wall to gas‐solid particulate systems. Considerable progress made in the last twenty years now permits a better understanding of heat transfer between a rigid wall and gas/solid particulate systems. The following paper reviews this progress. The heat transfer from a rigid wall to fixed, agitated, and fluidized beds as well as to fixed beds with fluid flow is discussed, and an example of indirect cooling of high‐capacity computers is given. In modelling, the concept of a contact and a penetration resistance in series is applied. The physical significance and the calculation of these resistances are discussed.
Vergleich von Laser‐ mit Elektronenstrahlschweißen
Authors: Anderl Peter
Published: December 2004

Comparison of laser with electron beam welding. International industry requires products of the highest technical standards thus requiring application of the technologically most efficient and most economical processes. For this reason, the electron beam and laser welding processes are becoming more and more important. To provide a workpiece‐relevant basis for deciding which technique should be used the following aspects will be investigated: generation of the beam, beam guidance systems, welding processes, application and power ranges, process controls, and equipment for industrial use. Finally a tabulated comparison should facilitate a detailed distinction between the two techniques.
Stoffumwandlung und Stoffaustausch bei Flüssig/Flüssig‐Systemen
Authors: Bart Hans‐Jörg , Marr Rolf , Bauer Andreas
Published: December 2004

Chemical reaction and mass transfer in liquid/liquid systems. In systems with mass transfer and chemical reaction, one has to consider the solubility of the solute in the receiving phase. Modelling of the phenomena will be according to gas/liquid systems for soluble solutes and according to gas/solid systems for insoluble solutes. Criterion for a further lay‐out of a contact apparatus is either the Hatta‐ or the second Damköhler number. This will be demonstrated for the extraction of copper as an example for a countercurrent cascade of mixers and countercurrent columns.
Sicherheitstechnische Kenngrößen und ihre Bedeutung für die Planung und den Betrieb von Chemieanlagen
Authors: Berthold Werner , Löffler Ulrich
Published: December 2004

Safety characteristics and their significance for planning and operating chemical plant. A knowledge of safety characteristics is a must for a safe operation of chemical processes. Disasters in chemical plant often occur due to a lack of knowledge of dangerous properties of the handled substances. Unexpected explosions or runaway reactions have been the result. Safety characteristics describe the reaction behaviour of substances as well as the fire and explosion hazards, provided that they are accurately determined and interpreted. This paper will sensitize research scientists, project engineers, and producers of chemicals to ensure that safety characteristics are correctly evaluated and applied in practice.
Rückgewinnung von Ammoniak aus Industrieabwasser
Authors: Marr Rolf , Končar Michael
Published: December 2004

Recovery of ammonia from industrial waste water. On the basis of new ecological findings, waste waters containing residual amounts of ammonia or ammonium ion formerly regarded as safe must now be classified as a serious potential hazard for the environment. Since new limits for ammonia/ammonium in waste waters are to be expected in the near future, considerable research and development work is currently being invested in the separation and recovery of ammonia. The present article considers the ecological problems relating to ammonium and states the sources of such effluents. Moreover, possible separation processes and recovery methods are reviewed and the pros and cons of the individual processes compared.
Polymerwerkstoffe im Chemie‐Apparatebau
Authors: Busse Horst , Schindler Helmut
Published: December 2004

Polymer materials in chemical plant equipment. The range and technical sophistication of organic materials today provide the chemical industry in particular with economical and highly dependable materials able to fulfill functions which previously required the use of expensive metals. Polymer materials suitable for use in chemical plant equipment can basically be subdivided into thermoplastics, elastomers, thermosets, and composites. They are used in the form of solid structures or as protective coatings. Recent years have seen a marked increase in the importance of self‐vulcanizing rubber linings for on‐site application (e.g. in sewage treatment and flue gas desulphurization plants), composite structures based on fluorinated polymers for acid recovery and electrically conducting polymers for the transportation of corrosive, combustible gases and vapours.
Mikroporöse Filtermedien für die Kuchenfiltration
Authors: Bott Reinhard
Published: December 2004

Microporous filters media for cake filtration.Improved knowledge about filtration conditions, capillary phenomena in filter cakes and in filter media, as well as the properties of membranes permit the use of microporous membranes in cake‐forming filtration. This allows removal of moisture without passage of gas and yields a particle‐free filtrate. Apart from metallic and ceramic membranes, polymeric membranes prove highly suitable as microporous filter media since they permit utilization of the entire range of filter equipment. The present article considers first the fundamentals of cake‐forming filtration, then surveys the various membrane systems, and finally discusses process‐engineering aspects of filtration with microporous filter media.
Zerstäuben von Flüssigkeiten
Authors: Walzel Peter
Published: December 2004

Atomizing of liquids. Atomizing of liquids, i.e. the formation of droplets in a continuous gas phase or in vacuum, is accomplished in most cases by atomizer nozzles. Single substance pressure nozzles and pneumatic atomizers or air blast atomizers are alternative devices for that purpose. The physical facts of the partition process of the liquid and two phase flow conditions are now better known thanks to recent investigations. This permits estimation of the effect of the most important parameters on the median drop size by equations of physically based dimensionless groups. The different methods referred to in the literature for determining drop sizes lead to different results and therefore still represent a problem. Nevertheless, an attempt is made to give simplified and physically sound equations for estimating droplet size for the most important kinds of atomizers. They provide the user with an overview of the principal influencing factors and should facilitate choice of a suitable atomizer. Besides the frequently applied methods for drop and spray formation, other processes are also described which are used in special cases.
EDV‐gestützte wissensbasierte Prozeßsynthese
Authors: Simmrock Karl Hans , Fried Birgit , Fried Andreas
Published: December 2004

Computer‐aided knowledge‐based process synthesis. Process synthesis as a branch of process development serves to structure chemical processes. Since it is largely influenced by trial‐and‐error knowledge, knowledge‐based programming resulting from AI research (Prolog, LISP, Shells) opens up new possibilities compared to conventional procedural systems (Fortran, PL/1). The immense area of knowledge of process synthesis soon requires subdivisions into smaller knowledge domains for which expert systems first arise as island solutions, which subsequently combine as cooperating distributed expert systems. A possible procedure is illustrated for the knowledge based process synthesis program PROSYN/REXPERT PLUS.
Abtrennung und Rückgewinnung von Stoffen aus Abluft‐ und Abgasströmen
Authors: Müller Günter , Ulrich Michael
Published: December 2004

Removal and recycling of components from air and gas waste streams. Removal and recycling of components from air and gas waste streams are becoming more important as purified gas streams must fulfil the requirements of national emission regulations (TA Luft in Germany). Processes for the removal of organic and inorganic components from gas streams are condensation, absorption, adsorption, and permeation. Physical principles, uses and limits of these processes, and appropriate apparatus are discussed.
Projektmanagement im Anlagenbau
Authors: Mosberger Erich
Published: December 2004

Project management in plant construction. Project management is a management concept increasingly employed in project execution both by industry and administration. There are variants to this management concept allowing it to be readily adapted to individual applications. Engineering companies are typically confronted with multi‐project management tasks, i. e. they handle concurrently a great variety of projects differing in size, complexity, and duration. For each project, specialists from various disciplines of the company have to be coordinated across department lines and their performance channelled under project management leadership. Matrix project management lends itself particularly well to this task, the personality of the project manager playing a central role.
Abtrennung und Rückgewinnung von Stoffen durch Adsorption und Ionenaustausch
Authors: Cornel Peter
Published: December 2004

Separation and recovery of materials by adsorption and ion exchange. Activated carbons are capable of removing dissolved organics from waste water. They can be used in granular or powdered form, instead of, before, during, or after biological treatment or in water recirculation systems. Usually the adsorbed organics cannot be recovered. Granular activated carbon can be regenerated by thermal reactivation. The use of other adsorbents such as adsorption resins is limited to special cases. Ionic compounds can be removed by ion exchange media. The most common of these are synthetic ion exchange resins. They are used for the treatment of rinse water and pickling effluent. Gold, silver, copper, mercury, chromate, etc. can often be recovered. The degree of separation achieved and the amount of regenerant required – which should be minimized for ecological and economic reasons – depend on process parameters and design.
Beiträge der Prozeßleittechnik zur Qualitätssicherung in der chemischen Produktion
Authors: Eckelmann Wolfgang , Schuler Hans
Published: December 2004

Contributions of Process Control to Quality Assurance in the Chemical Industry. Through their functions of measurement, i.e. the acquisition of quantities relating to the process and the product, and adjustment, i.e. the modification of control values, process control engineering and process automation represent the basis of all operative control of quality. The functions of control, regulation, and operator support are likewise instruments ensuring the maintenance of quality‐relevant process and product specifications. Utilisation of the considerable potential of these tried and tested control methods is logical in the case of chemical processes and should receive more attention in quality management.
Energetische Nutzung von Biomasse – Verfahren zur Herstellung von Synthesegas, Wasserstoff, Methanol und flüssigen Brennstoffen
Authors: Plzak Vojtěch , Wendt Hartmut
Published: December 2004

Die Verfahren zur Aufbesserung der Brennstoffeigenschaften von Biomasse orientieren sich weitgehend an der Vergasung oder Verflüssigung von Braunkohle. Die hydrierende Umsetzung der in der Biomasse vorliegenden Biopolymere (Cellulosen, Lignin und Lignocellulosen) erfordern vor dem hydrierenden Angriff den chemischen Abbau der komplexen Biopolymer‐Matrix. Man unterscheidet pyrolytische Verfahren (350 bis 500°C, drucklos) von den unter Druck durchgeführten hydrolytischen, solvolytischen und extraktiven Verfahren. Die relativ hohen Investitionskosten der Iysierenden Verfahren erfordern wegen der “Economy of scale” eine Mindestanlagengröße von mehreren hundert MW. Die Biomassevergasung und die darauf aufbauende Wasserstoff und Methanol‐Erzeugung aus Biomasse sind vom Investitionsaufwand her gesehen auch für kleinere Anlagen geeignet. In nächster Zukunft dürfte sich die energetische Biomassenutzung allerdings auf die direkte Verbrennung in Biomasse‐Heizkraftwerken bzw. die Vergasung und Verstromung des Gases in Brennstoffzellen beschränken.
Genehmigungsverfahren für Chemieanlagen im europäischen Vergleich
Authors: Stahl Harald , Betz Monika
Published: December 2004

Comparison of Licensing Procedures for Chemical Plant in Europe. In many European countries, licensing procedures for chemical plants are at present less laborious – much less, in some cases – than in Germany. In the countries of Southern Europe, in particular, the building license is granted separately from the operating license, enabling building work to begin at an early stage. On the one hand, processing periods and official management are able to facilitate and expedite the proceedings; on the other hand, increasingly complex approval procedures, such as the obtaining of a license under the German Federal Pollution Control Act, with an additional environmental impact assessment compatibility, result in further serious delays. The proposed EC Directive on the harmonization of licensing procedures will admittedly bring equality in terms of expense, procedure and duration, but Germany is likely to continue to play a pioneering role in plant‐related environmental protection, and hence also in the implementation of the licensing procedure, for a considerable period to come.