bluuebunny/crossref_metadata_2025 huggingface dataset:
Prognosen in der chemischen Technik
Authors: Collin Gerd
Published: December 2004

Forecasts in the chemical industry. Forecasts of the energy demand in the Federal Republic of Germany for 1985 predicted figures which were, in some cases, more than 100% higher than the actual consumption figures, due among other things to an unforeseen decrease in specific energy consumption, e. g. in the chemical industry to about half of that in 1960. Since 1973 the overall energy consumption in the chemical industry has remained almost unchanged at some 15 million t/year coal equivalents in spite of increased production. In future forecasts, these possible divergences between economic growth and energy consumption will have to be given far greater attention. In 1977/1978 forecast, figures were calculated for the material flow from the raw material to the end products in selected fields in the chemical industry by means of a simulation model. Some of these forecasts show satisfactory agreement, while some of them deviate to a greater extent from the actual production figures, partly due to unexpected drastic changes in import quotas for some basic chemicals and intermediates.
Wirtschaftlichkeit als Kriterium für die Entwicklung, Auslegung und Auswahl von Apparaten und Maschinen für Prozeßstufen
Authors: Nill Bernhard
Published: December 2004

Economy as a criterion for development, design, and choice of equipment and machines for process steps. The object of this paper is to show how a supplier of individual machines can influence the total costs of a chemical processing plant. This influence is quantified using actual examples based on the development of a product range, the optimizing and matching together of mechanical and thermal separation processes, and the selection of the most suitable types of equipment. Studies show that the products and services of an equipment manufacturer can influence substantially more than just capital investment costs and interest charges with their consequent effects on the annual running costs of a plant. It is possible to reach more economical solutions for important stages in a manufacturing process if the plant designers and the equipment manufacturers work closely together. A too tightly specified enquiry can prevent a manufacturer from offering the technically and economically optimized solution. By involving equipment manufacturers and correctly using their know‐how one can tap a substantial potential for the reduction of plant running costs.
Prüfmethoden für Kunststoffbehälter in der chemischen Industrie
Authors: Hessel Joachim
Published: December 2004

Methods of testing plastic vessels in the chemical industry. Methods are discussed for the testing of vessels made of thermoplastics and glass fibre reinforced plastics. Technical notes, guidelines and standards (DVS, VDI, DIN) describe methods of ensuring the quality of new containers. New testing methods have to be employed for equipment that has long been in use in order to provide subsequent confirmation of suitability. An appropriate concept is presented.
Verschleiß selbsttätiger Pumpenventile durch abrasive Suspensionen
Authors: Vetter Gerhard , Störk Ulrich
Published: December 2004

Wear of automatic pump valves by abrasive suspensions. In pumping of abrasive suspensions with reciprocating displacement pumps against high pressures, the pump valves prove to be subject to serious wear. Wear of the piston seal can usually be avoided by washing or by separating membranes. Pump valves are fitted with elastic or rigid seals. To resist corrosion and temperature effects, frequently the only possible approach is to finish them in metallic or carbide materials. The major kinds of wear are demonstrated by a tribological study. The rates of wear found for a real valve model with a high pressure experimental setup depend upon the pressure and frequency of reciprocation. A hardness‐dependent region of instability exists where wear scoring arises. The volume wear rate for various arrangements of materials and abrasive particles exhibits a crest/trough nature. A design strategy and construction aspects are considered and compared with practical experience.
Simulation industrieller Verbrennungssysteme
Authors: Görner Klaus , Zinser Walter
Published: December 2004

Simulation of industrial combustion systems. This contribution surveys the state of the art of mathematical modelling of industrial flames and combustion chambers with the aid of examples. No claim is made to completeness. It should be noted that the complexity of the mathematical model is limited by available computer power, even though this power is increasing, and one is thus compelled to concentrate on essential aspects in calculating combustion chambers. Nevertheless, valuable results are obtainable here, which often cannot be gained in a real system because the geometric dimensions are too large, or specific quantities cannot be measured, or a firing plant cannot be disturbed in operation. In the area of pollutant production, mathematical models help to provide an understanding of the operating mechanisms and possible means of influencing them. However, the greatest advantage over series of measurements lies in the possibility of performing parametric studies under otherwise identical conditions, which proves very difficult or impossible in practice.
Dia‐ und Ultrafiltration – Stofftrennverfahren in der chemischen Industrie
Authors: Samhaber Wolfgang M.
Published: December 2004

Dia‐ and ultrafiltration – separation processes in the chemical industry. The use of ultrafiltration membranes for purification and concentration of chemical or biotechnological products has a wide scope of application in industrial practice. Continuing development and improvement of membranes, and especially the increasing availability of favourably priced membranes for these applications, is increasing the use of these separation processes in chemical production. The present contribution deals with theoretical principles, potential applications, and aspects of industrial practice of these separation methods. Above all, the topic is surveyed from an industrial viewpoint.
Hydrodynamische Belastbarkeit von Mikroorganismen
Authors: Märkl Herbert , Bronnenmeier Reinhold , Wittek Bernd
Published: December 2004

Hydrodynamic stress resistance of microorganisms. The production of microbial metabolites and the growth of microorganisms are affected by mechanical forces, such as occur on stirring, pumping, and aeration in industrial equipment. This paper considers the methods of investigation and typical experimental results. The sensitivity of the organisms depends upon the stability of the cell wall and upon its morphology. Raising the viscosity of nutrient solution increases the symptoms of damage at a given stirrer speed. In the case of methane‐producing microorganisms, growth and product formation (methane production) are affected in the same manner. Physiological stress, induced for example by the absence of essential nutrients, proves additive to mechanical stress in its effect. It is suggested that the power dissipation per unit volume should be taken as a guide on scale‐up or on transfer of experience gained with one kind of flow system (e. g. jet flow) to another (e. g. stirred tank).
Die Schweißverbindung im chemischen Apparatebau und ihr Korrosionsverhalten im Betrieb
Authors: Bäumel Anton
Published: December 2004

Welded joints in the construction of chemical equipment and their corrosion behaviour in operation. This contribution surveys the possible kinds of corrosion damage to fully austenitic welded stainless steels in the presence of heat cracks. Such cracks can be avoided by the presence of ß‐ferrite. However, under certain conditions of attack ß‐ferrite can cause selective corrosion. That is especially so on decomposition of ß‐ferrite. Intercrystalline susceptibility in the zone of thermal influence can be avoided by use of stabilized or low‐carbon steels. The tendency to undergo granular disintegration increases with increasing nickel content. The resistance to pitting of stainless steels is reduced at places bearing tempering colour layers. Such layers should therefore be avoided in welding or they should be removed if they persist in formation.
Oberflächen‐ und Dünnschichttechniken in der Industrie
Authors: Menz Wolfgang
Published: December 2004

Surface and thin film technology in industry. Modern surface and thin film technology enables us to consider the bulk and surface properties of a material independently of each other. The advantages for industrial production are therefore the potential savings in materials and processing. This paper discusses selection of processes which have already become established in the automotive industry. A major topic in research and development of thin film technology is the change from open loop processes to closed loop processes. For that reason it is necessary to work on improvements to the analytical tools, on the one hand, and on the theoretical modelling of thin film structures on the other.
Elektrochemische Energieumwandlung in Brennstoffzellen
Authors: Wendt Hartmut , Jenseit Wolfgang
Published: December 2004

Electrochemical energy conversion in fuel cells. With the exception of high temperature fuel cells, fuel cells burn hydrogen fuel exclusively at low temperature giving energy conversion efficiencies of 40 to 60%. Alkaline cells, phosphoric acid cells, and membrane cells operate at low temperatures, whereas molten carbonate cells and zirconium dioxide membrane cells are designed as high temperature cells. The alcaline fuel cell has so far been used only for special purposes, such as space missions and miltary applications. The phosphoric acid cell is suitable for modular heating plant between 0.5 and 5 MW which are fueled with natural gas. It has demonstrated its technical reliability in a large‐scale field test in the USA and an economical breakthrough is expected in the next few years. The two high temperature cells face a longer development phase, yet hold promise of better econmic performance thanks to their greater efficiency.
Sicherheit im Chemieapparatebau mit Borosilicatglas
Authors: Wedel Walter
Published: December 2004

Safety in chemical equipment construction with borosilicate glass. Thanks in particular to its universal corrosion resistance borosilicate glass has acquired a firm place among the materials of construction for pipework, equipment, and plant in chemical engineering. Pertinent technical rules containing all necessary material data and regulations are available for design and planning. Observation of these regulations and adherance to appropriate designs ensure a high degree of safety in operation of glass installations in the rough conditions of a chemical plant.
Reinigung lösungsmittelhaltiger Abluft – alternative Möglichkeiten
Authors: Heck Günter , Müller Günter , Ulrich Michael
Published: December 2004

Purification of solvents containing air – Alternative methods. Different processes are used for the purification of solvents containing air: condensation, absorption, adsorption, combustion, membrane permeation, and biofilters or bioscrubbers. The processes will be explained by examples. The specifications required by “TA Luft” often cannot be reached only by condensation and membrane permeation. The success of absorption depends on the scrubbing liquid. Glycol ethers are useful scrubbing liquids – especially for chlorinated hydrocarbons. The choice of the process depends on the volume flow rate, the solvent concentration, and the kind of solvent. Recycling of the solvents reduces the costs of the process.
Hochreines Monosilan für die Elektronikindustrie – Synthese, Reinigung und Charakterisierung
Authors: Klockner Hans‐Jürgen , Eschwey Manfred
Published: December 2004

High‐purity monosilane for the electronics industry – Synthesis, purification, characterization. Monosilane is used in the electronics industry in the production of integrated circuits and in the manufacture of amorphous silicon devices such as solar cells, photocopier drums, and flat TV screens. The first German production unit for high purity monosilane gas which came on stream in 1987 is presented. The gas produced in a molten salt process is purified to highest quality and analyzed.
Verwertung von Klärschlamm
Authors: Wenning H. Peter
Published: December 2004

Gasification and pyrolysis of sewage sludges. Gasification and pyrolysis of sewage sludge were examined as alternatives to sewage sludge combustion. For this purpose, experimental gasification and pyrolysis tests were carried out with primary sewage sludge of Emschergenossenschaft. Main objective of these tests was the evaluation of yields and qualitites for products gained via sludge gasification or pyrolysis and an assessment of the environmentally relevant properties of the related residues. Both process alternatives enable the utilization of sewage sludge without any negative impact on the environment. Due to the total use of the organic components out of the sewage sludge in combination with an almost complete utilization resulting from the valuable hydrogen produced, gasification is an attractive alternative compared to the burning of sewage sludge, both from an environmental and an economic point of view. In the case of sewage sludge pyrolysis a portion of the organic components, however, will remain in the pyrolysis residue. Therefore, pyrolysis allows only a minor reduction of the residual product.
Wellenausbreitung in verfahrenstechnischen Prozessen
Authors: Marquardt Wolfgang
Published: December 2004

Wave propagation phenomena in chemical engineering processes. A phenomenological analysis of the dynamics of a number of different distributed parameter systems in chemical engineering reveals a surprisingly simple dynamic behaviour despite the complexity of the underlying nonlinear process models. Spatial structures or waves are propagating along a spatial coordinate during transients. The dynamics of most of the processes under consideration can be described with sufficient accuracy by three different model structures. These models serve as a basis for a theoretical system analysis. The investigation of characteristic properties of the propagating waves and the mechanisms responsible for wave formation are of central significance. Finally, it is shown how the extended knowledge about the processes may be applied for the solution of problems of technical interest.
Vergleich von Verfahrenskonzepten zur Rauchgasreinigung bei der Rückstandsverbrennung
Authors: Denzer Wolfgang , Faulhaber Friedrich Richard , Herrmann Eberhard
Published: December 2004

Comparison of process concepts for flue‐gas clean‐up in residue incineration. Depending on the residues being dealt with, industrial residue incinerators may produce flue gases having widely varying separation properties. This applies especially to particulate constituents. To determine unknown separation properties, to select suitable separation methods, and to predict the separating behaviour of the envisaged equipment, use can be made of pilot plants or very small test plants. Experiments have been carried out on two residue incinerators of different size using rotary‐kiln technology in order to ascertain the suitability of various processes for separating particles from flue gases. For wet treatment a venturi scrubber and a scrubbing column were investigated, and for dry treatment the methods of electrostatic precipitation and cloth filtration. Various alternatives for dust separation have been derived from, and assessed on the basis of, the experimental results. Discussion of the experimental results shows that reliable prediction of the operating behaviour of industrial‐scale units will require further basic investigations regarding dust separation and gas scrubbing. The task of enabling cleaned‐gas values to be reliably predicted is beyond the development potential of individual manufacturers, individual operators, and individual university institutes. What is essential is the development of a joint concept under which the various tasks will be distributed and coordinated.
Strahlungsaustauschrechnungen mit der Monte‐Carlo‐Methode. Theorie und Anwendungen auf technische Verbrennungssysteme
Authors: Görner Klaus , Dietz Uwe
Published: December 2004

Radiation exchange calculations by the Monte Carlo method. Theory and applications to industrial combustion systems. The goal of this contribution is to indicate possible applications of the Monte Carlo method to calculation of radiation exchange process in combustion plant. A brief introduction to the method is accompanied by an account of modelling of radiation exchange and a description of the optical properties of the combustion chamber suspension. The Monte Carlo model used is presented and special formulations are given. The application of the method for the calculation of technical combustion systems is illustrated for two large‐scale combustion plant (coal‐ and lignite‐fired). Flow and thermal yield are estimated in order to reduce the computational effort and to achieve industrially relevant applicability. The simulated results show good agreement with available measurements. Coupling with complete flame and combustion chamber models in which turbulent binary flow and local heat liberation are calculated is feasible and is discussed in the final section.
Die Anwendung von Expertensystemen zur Katalysator‐Entwicklung
Authors: Körting Erich , Baerns Manfred
Published: December 2004

Use of expert systems in catalyst development. Present‐day catalyst development is still based largely on empirical knowledge; in very few cases is it possible to design a catalyst solely on the basis of theoretical concepts. Expert systems, which make empirical knowledge available together with theory and in appropriate combinations should be utilizable for catalyst development. The article describes the present state of the art and indicates possible applications with the aid of an already developed prototype. The system suggests catalytically active components for hydrogenation of carbon monoxide to (1) methane, (2) C2+ hydrocarbons, as well as (3) methanol and (4) C2+ oxo products, and makes suggestions for choice of reaction conditions.
Trends beim Einsatz von Realzeitrechnern für Forschung und Entwicklung in der Technischen Chemie
Authors: Lübbert Andreas
Published: December 2004

Trends in the use of real‐time computers for research and development in industrial chemistry. Computers are integral parts of the complex equipment of chemical production plants. They are tools for computer aided process control. In production plants as well as in research and development laboratories, dedicated computer systems are used more and more. E. g., nearly all measuring devices will be controlled by their own microprocessors in the near future. In chemical engineering, however, the most significant developments are taking place in the software domain. The main trend in applications‐software developments is the enhanced importance of the support of the plant operators by means of improved user interfaces. Within the research and development field, the software must be more flexibly adaptable to changes in the process equipment and due to changing control algorithms than in production plants. Moreover, efforts are being made to improve control by exploiting as much as possible a priori knowledge on the system in question. A current development in this direction, which will become stronger with time, is known under the heading „expert systems”︁, in which heuristic know‐how of operators is made available and usable in process computers to improve control.
Auslegungskriterien für elektrostatische Emulsionsspaltanlagen
Authors: Draxler Josef , Marr Rolf
Published: December 2004

Design criteria for electrostatic de‐emulsifiers. Electrostatic de‐emulsifiers have been successfully used over many years for desalting of crude oil. The emulsions used for this application are rather unstable and break down easily. Different equipment and conditions are required for highly stable emulsions, such as are used for liquid membrane permeation. To permit use of higher field strengths without danger of short circuiting this new equipment must be fitted with insulated electrodes, with preference being given to glass‐insulated liquid electrodes. An important feature is also a defined distance between the electrodes which are arranged in concentric manner to increase the de‐emulsification rate. The rate of de‐emulsification can also be increased by using high frequency (10 kHz) instead of the usual low frequency (50 Hz) alternating voltage.
Ausbildung von Verfahrens‐Ingenieuren und Vergleich von Abschlüssen innerhalb der EG
Authors: Stephan Karl
Published: December 2004

Education of chemical engineers and comparison of qualifications within the European Community. The present survey compares and contrasts the various structures of engineering education, and especially of chemical engineering education, in the member countries of the European Community (EC). Each of the different education systems within the EC has its advantages and disadvantages and none of the systems is definitely superior to others. Each system is largely the product of national pecularities and should be seen in the light of the specific cultural background. This often impedes a complete transfer of single elements from one system to another. Proven principles of other education system should, however, serve much more than has been the case in past as a guideline for reforms in our country. Possible steps in this direction are discussed.
Herstellung und Anwendungsmöglichkeiten von Cyclododecatrien und Cyclooctadien
Authors: Streck Roland , Hartig Herbert
Published: December 2004

Production and applications of cyclododecatriene and cyclooctadiene. Today the cyclic trimerization of 1,3‐butadiene to cyclododecatriene and the synthesis of cyclododecatriene derivatives are accomplished on an industrial scale using fully developed processes. This paper surveys the variety of the derivatives and their applications. The cyclic dimerization of 1,3‐butadiene to cyclooctadiene and the synthesis of cyclooctadiene derivatives have also been performed on a technical scale for some years now. The paper gives examples of these derivatives, including polyoctenamer a rubber whose properties are considered to be due to the presence of cyclic macromolecules.
Exergetische Analyse und Bewertung verfahrenstechnischer Prozesse mit einem Flow‐Sheeting‐Programm
Authors: Munsch Martin , Mohr Thomas , Futterer Eberhard
Published: December 2004

Exergy analysis and assessment of process plants with flow‐sheeting systems. Mass and enthalpy balances are necessary for the calculation and assessment of process plants. The economic and ecological results cannot be optimal because the different value of energy according to the Second Law of Thermodynamics and the influence of the environment are not included. This is accomplished by exergetic analysis and assessment. The aim is to obtain an exergy analysis and assessment of any process plant through combination with a flowsheeting system. Because the exergy is dependent on the choice of a reference state, an environmental model is proposed which is suitable in regard to the above‐mentioned aim.
Neue Erkenntnisse zum Mischverhalten von Submersreaktoren
Authors: Lübbert Andreas
Published: December 2004

Mixing behaviour of submersed reactors. New improved measuring techniques lead to new insights into the local mixing behaviour of submerse reactors. As exemplified by airlift tower loop reactors, it is shown that it is possible to obtain more information from gas residence time distributions if the signal‐to‐noise ratio of the measurement can be improved significantly. Additional information is obtained, e.g., on that part of the gas recirculated around the loop or the circulation time of the gas phase. The recirculated gas significantly influences the gas backmixing in such reactors. A more thorough investigation of the gas phase motion requires locally resolved data. For the properties of the gas phase, local measuring techniques are available, which allow for measurements of the mean bubble velocity profile even during production runs in large aerated stirred tank reactors. The results show that the gas backmixing is acutely dependent on the viscosity of the continuous liquid phase. Complementary measurements on the properties of the continuous liquid phase can be investigated by means of the heat‐pulse‐technique. This also is applicable in real media, e.g., during biotechnological cultivation runs. Besides the measurement of the mean liquid velocity, one can, furthermore, obtain some information on the locally dominating mixing mechanism. One significant result of such investigations is that in the airlift reactors investigated the bubble‐wake mixing mechanism dominates, whereas the isotropic turbulence in terms of the statistical turbulence theory plays a secondary role. This even holds at very high energy inputs.
Rechnergestützte exergetische Optimierung verfahrenstechnischer Prozesse
Authors: Futterer Eberhard , Gruhn Günther , Munsch Martin , Mohr Thomas
Published: December 2004

Computer‐aided exergy optimization of chemical engineering processes. Methods of exergy evaluation as the basis of energy and material analysis of chemical processes have been used for some years to evaluate these processes from the view point of the First and Second Law of Thermodynamics and with regard to their influence on the environment. This paper introduces a tool for computer‐aided exergy analysis and optimization of complex process plants. This tool is based on a flowsheeting program that is extended to calculate the exergy of material, heat, and work flows. The optimization problem of process plants is solved in a two level approach by parameter optimization and structural optimization. The parameter optimization is realized automatically by the extended flowsheeting program. The structural optimization is based on heuristic rules and experiences of the process engineer.
Ultrareinigung organischer Substanzen durch Schmelzkristallisation
Authors: Arkenbout Gerard
Published: December 2004

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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