bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Auslegung von Kühlerkondensatoren zur partiellen Kondensation von Dämpfen aus strömenden Gas/Dampf‐Gemischen
Authors: Rennhack Rolf , Numrich Reiner
Published: December 2004

Dimensioning of cooler condensers for partial condensation of vapours from gas‐vapour mixtures. This contribution surveys present knowledge in the field of partial condensation with related hints about dimensioning cooler condensers. In case of an atmospheric and slightly increased pressure and moderate shearing forces of the gas‐vapour mixture on the condensate film being formed, the film theory is sufficient. However, it is necessary to include the Stefan correction for unilateral diffusion. High sharing forces lead to entrainment. The results of the few experimental publications show that the film theory is no longer valid immediately before entrainment is reached. Nor can it be used in the area of high pressure. There are not enough experimentally and theoretically proved correlations for dimensioning so that it is necessary to use empirically found average overall heattransfer coefficients. The use of well‐known correlations to determine limits of entrainment makes it possible to prove whether the film theory is valid or not in every single case.
Fortschritte bei der Abscheidung von Stäuben im Elektrofilter unter Berücksichtigung der Schadgas‐Adsorption
Authors: Mayer‐Schwinning Gernot
Published: December 2004

Progress in dust collection by electrostatic precipitators with due attention to adsorption of noxious gases. It is shown on the basis of the present state of the art that the stipulations of the pollution control legislation for large boilers can be met by electrostatic precipitators and that fine dust and heavy metals are collected to a sufficiently high degree. Recent developments are dealt with which bring about a fundamental improvement of the collection in the precipitator. Noxious gases have to be separated together with the dust to an ever‐increasing extent. With dry processes, fluidized beds are arranged upstream of the electrostatic precipitator for the adsorption of, for instance, HCl, HF, and SO2. In these cases the dusts will be highly concentrated and of varying chemical composition. Dry gas cleaning in the expanded, circulating fluidized bed downstream of refuse incineration plants and defluorination of waste gases from aluminium electrolysis are considered as examples. The separation of dust under difficult conditions is then dealt with.
Schadensuntersuchung an organischen Werkstoffen im Chemie‐Apparatebau
Authors: Schindler Helmut , Gräfen Hubert
Published: December 2004

Investigation of damage to organic materials in chemical apparatus engineering. There are many different possible causes for the failure of structural elements or of linings and coatings made of organic materials under such load conditions as those found in chemical plant. Despite the general suitability of the engineering plastics used, design and manufacturing defects are often the cause of premature failure. Installation faults are also found on occasion. Other sources of damage include the chemical and physical effects of media on organic materials. These are due in part to the unsuitability of the material used, the effect of corrosive components in the media involved often being either not recognized or underestimated; on the other hand, the damage may also be caused by inherent stresses in the structural elements in conjunction with the physical or chemical effects of the media, resulting in stress cracking or stress corrosion cracking. Damage cases of this type are described on the basis of numerous examples, the causes ascertained through intensive investigation of the damage and suitable remedies described.
Lösungsmittel‐Auswahl bei der Flüssig/Flüssig‐Extraktion unter physikalisch‐chemischen Aspekten
Authors: Hampe Manfred J.
Published: December 2004

Selection of solvents in liquid‐liquid extraction according to physico‐chemical aspects. Selection of appropriate solvents for liquid‐liquid extraction is frequently necessary in process design. High selectivity and capacity are important, but not the only considerations in choosing suitable solvents. In comparing the various solvents, their selectivity and capacity should be examined at infinite dilution of the solute in the solvent. The required limiting activity coefficients may be estimated if no experimental data are available. A preselection of solvents may be accomplished by considering the interactions of the molecules. There are certain parameters quantifying the ability of the components to interact. Therefore, a selection based merely on dielectric constants or solubility parameters is hardly conclusive.
Reaktionstechnische Aspekte der katalytischen Abgasreinigung bei Kraftfahrzeugen
Authors: Löwe Arno , Hoffmann Ulrich
Published: December 2004

Kinetic aspects of the catalytic detoxification of automobile exhaust. The technology of catalytic converters designed to reduce automobile exhaust emissions has developed considerably in recent years, as is well documented in the available literature. This review is intended to show how the methodology and philosophy of chemical reaction engineering have contributed to this development. A brief survey of possible reactions and actual catalysts is followed by a detailed account of the relevant basic principles of micro‐ and macrokinetics. Preliminary calculations of conversion of noxious substances in monolithic converters may be based upon the assumption that diffusion from the laminarly flowing gas phase to the catalytically active wall coating is the rate‐determining step in a warmed‐up converter. During the critical warm‐up period, after a cold start, the chemical reaction steps offer the main resistance. The points discussed are the extent to which rate equations and kinetic parameters will be influenced by high degrees of dispersion of the noble metals, by catalyst deactivation, or by transient operation conditions. The structure of the highly porous catalyst support as well as metal impregnation profiles can be optimized so that poisoning is strongly retarded by in‐pore diffusion, while the main reactions are affected as little as possible.
Expertensysteme für die Verfahrenstechnik
Authors: Lieberam Armin
Published: December 2004

Expert systems in chemical and process engineering. A survey is given of expert systems in chemical and process engineering and adjacent fields of knowledge. The article assumes a knowledge of the basic concepts of artificial intelligence and expert‐system technology. The expert systems, arranged according to their function and domain of expertise, are described and discussed with emphasis on information of interest to the potential user, e.g. on applications, construction, and implementation. Finally, an attempt is made to give an outlook on future applications of technical expert systems and on the abilities which these systems are expected to possess.
Zukünftige Chancen einer elektrochemischen Kohlenutzung
Authors: Kochanek Wolfgang , Kreysa Gerhard
Published: December 2004

Future scope of electrochemical coal utilization. Based on fundamental thermodynamic considerations and with due regard to known electrochemical reactions of coal‐like substances, the potential of electrochemical coal conversion processes is discussed for the following three main groups of primary products: syngas, aliphatic compounds, and aromatic compounds. Thermal efficiencies and yields are compared with those of competing processes. The indirect electrochemical degradation of coal to soluble aromatic compounds with peroxodisulfate as redox mediator is a promising route of potential interest.
Kinetik der aeroben Abwasserreinigung durch Abbau von organischen Verbindungen und durch Nitrifikation
Authors: Wiesmann Udo
Published: December 2004

Kinetics of aerobic waste water treatment by degrading organic compounds and by nitrification. Both aerobic degradation of organic substances and nitrification can be described by the double substrate kinetics of Monod; dissolved organic material and ammonium or nitrite are the first substrate and oxygen the second one. The determination of the different kinetic coefficients by evaluation of measurements on a laboratory scale is explained first, and known results are then presented and discussed. Finally, it is demonstrated by two examples, viz. the simultaneous oxidation of carbon and nitrogen compounds and oxygen‐limited substrate removal, how reaction kinetic models can be used to obtain important information about the characteristics of the bioreactions.
Formselektive Katalyse in Zeolithen
Authors: Weitkamp Jens , Ernst Stefan , Dauns Harald , Gallei Ewald
Published: December 2004

Shape selective catalysis in zeolites. In recent years, shape selective catalysis has become an important field of heterogeneous catalysis. Shape selectivity can arise if the pore width of the catalyst resembles the dimensions of molecules or transition states involved in the catalytic reaction. Up till now, zeolites are employed almost exclusively as shape selective catalysts. Examples of the different kinds of shape selectivity are given. The classification of Weisz and Csicsery is presented. More recent concepts are discussed. Measures for a control of shape selectivity are outlined. For a routine characterization of shape selective catalysts, certain test reactions are shown to be useful tools; the two most important examples are the determination of the constraint index and the hydroconversion of long chain n‐alkanes.
Reaktorstabilität und sichere Reaktionsführung
Authors: Eigenberger Gerhart , Schuler Hans
Published: December 2004

Reactor stability and safe reaction engineering. Stable operating behaviour of chemical reactors and stability in the sense of stability theory of chemical processes are by no means synonymous concepts. Thus, appropriate control can permit reliable operation at a unstable operating point, while even global stability will not necessarily rule out a runaway reaction. The latter is the case when strongly exothermal reactions are characterized by a pronounced parametric sensitivity. In order to delineate the concepts, „stability”︁ and „parametric sensitivity”︁ are explained first for stirred tank and tubular reactors with strongly exothermal reaction. Both the conventional view of reaction engineering and the theory of heat explosion commonly used in reaction engineering are considered in detail. Practical problems of safe reaction engineering are subsequently discussed for the control of batch reactors, the control of semibatch reactors, and the behaviour of bundled‐tube reactors.
Zerstörungsfreie Prüfungen bei Betrieb und Instandhaltung von Chemieanlagen
Authors: Gräfen Hubert , Steiger Klaus
Published: December 2004

Non‐destructive testing in operation and maintenance of chemical plant. Non‐destructive tests performed in chemical plant while it is in operation or standing idle are intended to give the plant operator the information on the state of the plant that is needed to ensure safety and availability. The scope of such tests and how often they are carried out depend on the condition of the plant and on the weaknesses that have been found in the course of time. The following are described as special examples of the versatile use of non‐destructive test methods: (a) thermographic and ultrasonic checking of the condition of a rotary furnace; (b) observation of spherical ammonia containers to ensure early recognition of cracking; (c) detection of leaks in high pressure plant items having corrosion resistant linings; (d) metallography of structural element subjected to heavy loads for long periods at elevated temperatures; (e) wall thickness measurement of heat exchanger tubes; (f) on‐site gamma radiation analysis of metallic materials with an portable RFA device.
Verschmutzung in Kondensatoren und Kühltürmen
Authors: Paikert Paul
Published: December 2004

Contamination in condensers and cooling towers. Considerable changes in thermal performance or the condensation temperature of water‐cooled condensers must always be expected on contamination of the heat exchange surfaces of equipment with high thermal loading. This is practically always the case with water‐cooled condensers of large‐scale steam turbines, whereas air‐cooled condensers on the coolant side work at only low heat flow densities and therefore react much less sensitively to contamination. This article describes relations between contamination and loss of performance in various systems, and commercially available means of prevention and cleaning are indicated. This state of the art description includes measures for cleaning wet and dry cooling towers.
Herstellung und Instandhaltung verfahrens‐technischer Einrichtungen aus der Sicht des Betreibers
Authors: Hedden Horst
Published: December 2004

Production and maintenance of chemical engineering equipment from the viewpoint of the operator. Maintenance of chemical engineering plant is cost intensive, owing to the large size of such installations. A large variety of heavily taxed units in long term use necessitates constant maintenance. All possible means of cost reduction must therefore be exploited. Collaboration between manufacturer and maintainer is one possible area for such measures. All joint efforts must be directed to the faultless unit. Such efforts are nearly always possible without affecting the manufacturing costs of the unit. Various forms of collaboration are conceivable.
Aufgabenstellung und Konzeptfindung bei einer thermischen Abluftreinigung
Authors: Hüning Werner
Published: December 2004

Task definition and concept development for a thermal waste air purification system. The present report demonstrates how the properties of waste air and the boundary conditions of the task lead to direct, compelling consequences for the concept, the realization, and the operation of a thermal waste air purification unit. The design of the individual functional groups is always a result of the job criteria and possible influences of other functional groups. The better the adaptation of the plant concept to the demands of the task, the more smoothly the finished plant will run. Very high availability and reliable waste gas quality represent the principal environmentally relevant objectives of such thermal waste gas purification plant. Thermal waste gas/exhaust air purification is presently the most universal procedure for optimum, environmentally appropriate purification.
Experimentelle Identifikation und rechnergestützter Regler‐Entwurf bei technischen Prozessen
Authors: Hensel Hartmut , Isermann Rolf , Schmidt‐Mende Peter
Published: December 2004

Experimental identification and computer‐aided control design in technical processes. The transient behaviour of complex processes, such as frequently occur in process engineering, is often known only inadequately, since theoretical (physical) model formation is extremely difficult owing to insufficient knowledge of internal processes. If satisfactory quality of control is to be achieved, then a viable approach is experimental model construction (identification) on the basis of a mathematical process model. Modern computer‐aided identification procedures and computer‐aided control design procedures based thereon or self‐adjusting controls give particularly good results. Furthermore, the design time required is greatly reduced, meaning that computer use can also contribute to considerable saving of costs.
CAD in der Anlagentechnik – Gegenwärtiger Stand, Probleme und Chancen
Authors: Futterer Eberhard
Published: December 2004

CAD and plant engineering. State of the art, problems, and prospects. CAD was first used for special tasks, that is for especially sensitive design, e. g. in the aircraft industry, or mass‐produced articles, e. g. in the automotive industry. For about one decade, CAD has been used economically in all areas of design. This paper describes the state of the art of CAD use for plant engineering. It may be seen as the termination of a thorough test. Now the time has come to decide on the future use of CAD. Problems encountered are therefore reported. The prospects of CAD are outlined on this basis.
Thermisches Spritzen im Chemieapparate‐ und Maschinenbau – Anlagen, Werkstoffe, Anwendungen
Authors: Kreisel Klaus , Protogerakis Emmanuil
Published: December 2004

Thermal spray technique in chemical equipment and machine construction – Plant, materials, applications. The metal spray technique originally used only for repair applications is nowadays also used for production of new equipment since the attainable life expectancy of the coated parts plus the possibility of using inexpensive basic materials result in a significant increase in economy. The use of thermal spray coats in the manufacture of chemical plant calls not only for high adhesion and freedom from pores and cracks but also for good corrosion resistance. The high technological level which has been reached in spray processes as well as the development of suitable spray materials have meant that a satisfactory solution has now been found to a large number of the problems that were still outstanding a few years ago.
Verwendung von Kohlenstoff‐Fasern im Apparatebau
Authors: Böder Horst , von Gellhorn Edgar , Künzel Jürgen
Published: December 2004

Use of carbon fibres in equipment constuction. Carbon fibres are characterized by high tensile strengths, high modulus of elasticity, and good corrosion resistance. They are therefore especially suitable for reinforcement of components made of plastics (CFC). Carbon fibre reinforced parts made of resin‐impregnated graphite withstand higher mechanical stress and offer greater reliability in operation. CFP materials is an economical alternative to high‐alloyed steel for use in corrosive media. Apart from graphite CFC is one of the few materials of construction suitable for use up to temperatures of over 2000 °C. It has also been sucessfully used for highly corrosion‐resistant equipment such as grids and piping.
Stand der Technik der Oberflächenveredelung durch Laser
Authors: Mordike Barry Leslie
Published: December 2004

State of the art of surface treatment by lasers. Lasers have a great future in surface treatment. Laser surface treatment should not be regarded as a replacement for existing methods. It cannot compete with mass production methods, but can be used whenever a local need arises for special properties or when conventional methods fail. Some new developments, such as laser gas treatment, are also extremely promising.
Fortschritte auf dem Gebiet der Alkalichlorid‐Elektrolyse
Authors: Bergner Dieter , Hartmann Manfred , Staab Rudolf
Published: December 2004

Progress in the field of alkali chloride electrolysis. In the field of alkali chloride electrolysis, new developments are restricted almost solely to the membrane cell process, and no longer concern the conventional mercury and diaphragm processes. At present, the membrane process has a roughly 10% share of the world's caustic soda production capacity of about 48 million t NaOH/a. This share includes membrane cells and retrofit diaphragm cells. After dealing with electrolytes and electrolysis products, this review then turns to a discussion of the optimum current density, of cell voltages, current efficiency, and energy consumption. Subsequently, economic aspects are considered in relation to energy and capital expenditure costs as well as to plant construction. Finally, the most recent developments are discussed, especially in the field of oxygen consuming cathodes in membrane cells.
Modelle für die Berechnung der Leckraten aus druckführenden Apparaten und Rohrleitungen in Chemieanlagen
Authors: Friedel Lutz , Westphal Frank
Published: December 2004

Models for the calculation of leakage rates from pressure equipment and pipes in chemical plant. A survey of the possible sizes and sites of leaks and of the calculation models hitherto described in the literature shows that the leaks to be expected can only be small slit shaped cracks in the walls of vessels and pipes. Depending upon the location of the leak, gas/vapour or liquid flow, or even two‐phase flow is to be expected from the leak. Only very few semiempirical models are available for calculating two‐phase mass flow density through slits with very small dimensions, such as slit widths of about 0.1 mm; moreover, such models contain only empirical factors which were adjusted to experiments with initially supercooled water. Experience tells us that such relationships cannot be straightforwardly and reliably applied to the exiting of substance systems typical of chemical plant.
Gaswaschanlagen für saure und basische Abgase unter Berücksichtigung der neuen TA‐Luft
Authors: Schaber Karlheinz
Published: December 2004

Gas scrubbing plants for acid and caustic exhaust gases with consideration of the new TA‐Luft. When designing gas scrubbing plants for acid and caustic exhaust gases from manufacturing plants of the chemical and pharmaceutical industry it is important to pay special attention to the aerosol formation which occurs in the exhaust gas systems and absorbers if the emission values should remain under the determined limit values stated in the Technical Instructions for air‐pollution control (TA‐Luft). The present study explains under what conditions aerosols can occur, how its formation can be prevented, and which gas scrubbers are appropriate for a combined gas‐/aerosol separation. A comparison between two exhaust air scrubbing plants of several stages shows that a gas scrubbing plant for an exhaust air pick‐up system with separation of the acid and caustic components as well as with source exhaust air pick‐up of the highly charged gas flows is considerably more favourable with respect to price than the alternative scrubbing plant for an integrated exhaust air system in which large quantities of fine salt aerosols occur and have to be separated with high energy consumption.
Entwicklung des Pauling‐Verfahrens zur Regeneration von Abfallschwefelsäure
Authors: Plessen Helmold Von , Schalles Horst
Published: December 2004

Development of the Pauling process for regeneration of spent sulphuric acid. The Pauling rectification process has proved a successful method of regenerating spent sulphuric acid. The further development of the process in the last ten years has included the production of cast iron materials with improved corrosion resistance for use in the boiling vessels. Other development work concerns the operation of the stirrers and the apparatus, the construction of stripping columns, and the introduction of new types of cooling equipment for the hot concentrated sulphuric acid. Furthermore, the scrubbing of the exhaust gases leaving the Pauling apparatus must be adapted to more stringent demands, also with regard to the increasingly varied composition of the spent acids.
Zeitlicher Druckverlauf bei Explosionen als Grundlage zur Auslegung von Behältern und Apparaten
Authors: Gruber Udo , Puppich Peter , Noll Ewald , Mewes Dieter
Published: December 2004

Time‐dependent behaviour of pressure in cases of explosions: A basis for design of pressure vessels and apparatus. The knowledge of the maximum explosion pressure is important for design of pressure vessels subject to danger of explosion. Especially for non‐spherical geometries or plant‐internal pressure relief, the maximum explosion pressure has to be calculated from the time‐dependent pressure caused by a chemical reaction in the vessel. Therefore, a set of ordinary differential equations was solved numerically by means of the method of differences. Examples are drawn from known experimental studies. Turbulence effects are also considered. As a result, an analytical relationship is derived which gives the necessary pressure relief area. Finally the results are compared with those of available formulas. Deviations are explained in detail.
Maßnahmen zur Verhütung einer Wassergefährdung beim Umgang mit wassergefährdenden Stoffen
Authors: Stahl Harald
Published: December 2004

Measures preventing water contamination during the handling of potential contaminants. Processing plant, filling plant, storage and refilling plant, where substances endangering water are handled, must be designed in such a way that they represent no danger to bodies of water in operation. This requires that any such substances released due to plant failure or any other reason must be quickly recognized, and reliably collected and removed without any threat to the water. Examples of technical, organisational, and infrastructure measures designed to achieve the set goal are given for each of the types of plant mentioned. Demands placed on cooling water systems in processing plant are likewise considered.
Auswahl und Auslegung thermischer Trennprozesse mit Hilfe von Gruppenbeitragsmethoden
Authors: Gmehling Jürgen , Tiegs Detlef , Weidlich Ulrich
Published: December 2004

Selection and design of separation processes using group contribution methods. Separation processes can be designed by solving so‐called MESH equations. In spite of the large number of equations and unknowns, modern computers and numerical methods permit the rigorous solution of the resulting equations. The exactness of the design is influenced only by the accuracy of the K factors and enthalpy data used. Great progress has recently been made in the field of phase equilibrium thermodynamics. While 20 years ago, a great number of time consuming and expensive experiments were necessary to describe the real behaviour of multicomponent systems, today this behaviour can be predicted using binary information or group contribution methods.
Nutzung von Laser‐Raman‐Verfahren in der Verbrennungstechnik
Authors: Leipertz Alfred
Published: December 2004

Use of laser Raman processes in combustion engineering. The utility of various laser Raman processes is surveyed. The author presents a general consideration of applicability, focussing mainly on linear Raman scattering and the nonlinear CARS effect, and making fundamental observations on the measuring procedures and the possibilities they offer for local and time‐based high‐resolution acquisition of temperature and concentration data in combustion processed. Results are reported. The scope for obtaining not only pointwise but also linearly and fieldwise distributed information with high time‐resolution is discussed.
Kreiselpumpen und Energierückgewinnungs‐Turbinen in der verfahrenstechnischen Hochdrucktechnik
Authors: Franke Hans‐Joachim , Hofmann Heinrich , Jeske Hans‐Otto , Schill Jürgen
Published: December 2004

Centrifugal pumps and energy recovery turbines in high pressure industrial process engineering. Centrifugal pumps have to meet many different requirements in high pressure industrial process engineering. International standards call for minimum requirements and propose solutions for various problems. Nevertheless, options remain for the operator with regard to the choice of the casing, material, and sealing variants, and to the choice of hydraulics to meet such requirements as reliability, safety, service‐friendliness, economic efficiency, and investment cost. The following review presents various designs of centrifugal pumps for high pressure industrial process engineering. Furthermore, the installation of high pressure pumps in turbine operation for energy recovery is introduced.
Gleichgewichtsdarstellung und technische Apparate bei der Neutralisation alkalischer Wässer mit CO2
Authors: Höll Wolfgang H. , Balduhn Reinhard
Published: December 2004

Equilibria and technical equipment for neutralization of alkaline water with CO2. Alkaline water can be neutralized by means of carbonic acid. The particular advantages of this method are that there is no increase in the content of neutral salts and that the product water is well buffered and therefore does not favour corrosion. Furthermore, neutralization can easily be combined with an aeration. The paper discusses physico‐chemical fundamentals and presents some neutralization devices.
Polymerisationstechnik
Authors: Reichert Karl‐Heinz
Published: December 2004

Polymerization engineering. Polyreactions are complex chemical reactions which are generally conducted in liquid phase. The characteristic feature of polyreactions is the pronounced increase in viscosity of the reactants during the reaction. The increase in viscosity influences numerous reaction and process parameters, such as the reaction kinetics, the transfer of mass, heat, and momentum, the degree of mixing of the reactants, and the residence time distribution of continuous reactors. Thus the increase in viscosity influences the performance, selectivity, and safety of the reactor. The choice of reactor for performing polyreactions can be based on various aspects. Of decisive importance are the performance and selectivity of the reactor. For the cases of simple and complex polyreactors, various kinds of reactors are compared with respect to their performance and selectivity, with the molar mass distribution of the resulting polymers serving as example of the selectivity of polyreactions. In the case of simple polymerizations, the molar mass distribution of the polymers depends unequivocally on the type of reactor and the various reactor types can be arranged in appropriate order. This is no longer the case for more complex polymerizations because the concentration conditions in the reactors play an increasingly important role.
Planung einer Verbrennungsanlage für industrielle Rückstände
Authors: Seifert Helmut , Hasberg Willy , Dorn Ingo H.
Published: December 2004

Design of an incinerator for industrial waste. For many years rotary kilns have been used in combination with an afterburner chamber followed by a steam boiler at BASF to incinerate the waste of chemical plants. Six incineration lines are available at the moment. As the amount of waste is always increasing an additional incinerator was necessary on increasing the incineration capacity a new flue gas cleaning system would have to be installed, not only for the new incinerator but also for the flue gas of five of the existing furnaces. The cleaning system will be done in two lines, each of them consists of an electric precipitator and a multistage scrubber. In order to design the new incinerator line, not only many operating conditions and legal prerequisites but also constructional and combustion requirements had to be considered. While the design of the rotary kiln is based essentially on empirical coefficients, e. g. on the burning load related to the furnace volume, the design of the afterburner chamber was made by the help of a numerical computation model supported by experimental model investigations. A further focal point was optimizing the operation of the waste burner which gave a primary reduction of the NOx emission.
Entsorgung von Öl‐in‐Wasser‐Emulsionen durch Elektrokoagulation
Authors: Gidarakos Evangelos , Köhling Alfons , Schmitt Rolf‐Erhard
Published: December 2004

Separation of oil‐water emulsions by electrocoagulation.Separating emulsified fluid drops or suspended solid particles from oil‐water mixtures is one of the central problems of disposal technology. Reprocessing used emulsions or suspensions, however, is complicated by emulsion stabilisers and impurities. The efficiency of mechanical separation methods often leaves much to be desired, so that flocculants or demulsifiers are added. These additives are expensive, produce secondary waste, and may have adverse effects on the properties of the resultant product as far as its reuse or disposal is concerned. Electrocoagulation, a treatment process developed at Battelle, has none of these drawbacks. It is based on the fact that the stability of colloids, suspensions, and emulsions is critically influenced by electric charges being repelled by like charges on the surface of particles. Therefore, if additional electric charges are supplied to the charged particles via appropriate electrodes, the surface charge of the particles is neutralised and several particles combine into larger, separable agglomerates. The process‐technological design is such that the emulsion (or suspension) flows through an electrochemical cell where it is demulsified. Energy consumption for this is low, chemicals need not be added, and no secondary waste results. Thus, a pretreatment process is available with which the separating efficiency of existing processes can be increased without having to modify the relevant apparatus significantly.
Möglichkeiten und Problemlösungen der Stromerzeugung mit Windkraftwerken
Authors: Mühlöcker Hugo
Published: December 2004

Scope and problem solutions of power generation by wind‐driven plant. The importance of wind power has changed in the course of history with the advent of competing energy converters for power production from coal, oil, and nuclear energy. The known physical laws of aerodynamics and geographical location ascribe wind power a market share of no more than a few percent of power generation. Among the many designs of wind turbines, only 2‐ and 3‐blade propeller turbines have been produced in large quantities with power ratings up to ca. 4 MW. Market developments have so far been determined by government funding. The power generation costs of 0.25 to 0.30 DM/kWh are still too high by a factor of 2 to 3. With regard to future developments it remains to be seen whether the use of more sophisticated generator systems will permit the expected large savings on the mechanical side and thus open the path to economic large production runs also in the case of medium and large‐scale units.
Konstruktive Besonderheiten bei großvolumigen GFK‐Apparaten mit Einbauten
Authors: Klein Andreas , Schellenberg Rolf
Published: December 2004

Constructional features of large‐volume FRP vessels with internals. Especially in the case of large vessels with internals subject to corrosive attack (such as absorption towers and scrubbers in FGD plants) the use of FRP, particularly those based on vinyl ester resin, provides many advantages over conventional solutions such as stainless steel or rubber lining. The vessel's large dimensions may lead to relatively large deviations from target dimensions. In certain cases this may require departure from established design practice in order to ensure the benefit of easy on‐site assembly and erection. The following article presents design details for large FRP vessels, i. e. fixing of internals inside the vessel, fixing of vessel on its foundations, and supporting of platforms and piping outside a free‐standing tower.
Heizen und Kühlen –‐ verfahrenstechnische Aspekte
Authors: Stephan Karl , Slipšević Boris
Published: December 2004

Heating and cooling‐chemical engineering aspects. This paper reviews the commonest types of heat exchangers and their applications. They are classified in the following types: tube bundle heat exchangers, plate heat exchangers, spiral heat exchangers, lamella heat exchangers, and heat exchangers for special purposes. Most of these apparatus can be used for heat exchange between single phases or for condensation or boiling of substances. The different criteria determining the choice of heat exchanger are explained.
Thermodynamische Bewertung chemischer Reaktionen, dargestellt am Beispiel der Ammoniak‐Synthese und der Wasserstoff‐Dissoziation
Authors: Bauer Bernhard
Published: December 2004

Thermodynamic evaluation of chemical reactions, illustrated for ammonia synthesis and hydrogen dissociation. Chemical reactions can be evaluated with regard to the efficiency of energy conversion – in the light of the second law of thermodynamics – without any need to introduce a material sink of average composition of the environment as model environment, as required by the exergetic method of evaluation. The method developed is described in this article. It is designed for universal application beyond the bounds of range indicated here so that widely differing cases of energy conversion can be optimised and made comparable, always using the same calculation scheme.
Wirtschaftliche und technologische Bewertung von Verfahren
Authors: Frey Walter , Heimann Frank , Maier Siegfried
Published: December 2004

Economic and technological evaluation of processes. The process engineer is finding it increasingly important to evaluate a given process from the economic and technological standpoint, when developing a process or realizing an investment project. In order to demonstrate the possibility of a structured and systematic mode of procedure, a brief account is given of the available tools. Profitability can be evaluated on the basis of the accounting rate of return (ROI), the internal rate of return (dcf yield), and the ratio of equity, all measures that can be derived from an assessment of costs and economics. To take into account the uncertainty of the boundary conditions assumed, such as raw materials costs, selling prices, and plant utilization, it is advisable to carry out a risk and sensitivity analysis. Examples are given that demonstrate the possibility of both calculating and reducing the economic and technological risks.
Flow‐Sheeting‐Programme für die Prozeßsimulation
Authors: Futterer Eberhard , Munsch Martin
Published: December 2004

Flowsheeting systems for process simulation. Simulation of process plants with flowsheeting systems has been state of the art in chemical plant design and in the chemical industry for many years. Modern computers now permit steady state simulation of complex chemical plants with sufficient accuracy. This paper outlines the different approaches to steady state process simulation, names the advantages and disadvantages, and gives an outlook on further developments. Process optimization, process integration, and process synthesis will be discussed. The integration of different programs, e.g. the connection between flowsheeting systems and computer‐aided design (CAD) will be described. An advance in user friendliness will be reached by latest developments in the field of personal computers and workstations and by database management systems.
Anwendung von statistischen Prüfverfahren im Bereich der Mischtechnik
Authors: Raasch Jürgen , Sommer Karl
Published: December 2004

Application of statistical testing to mixing. Assessment of the homogeneity of mixtures of solids and determination of the necessary mixing times are performed with the aid of statistical testing methods. The results from the basis for necessary decisions. Since reliable statements are fundamentally impossible in mathematical statistics, all such decisions are, with a certain probability, false, i.e. involve some risk. In studies of mixing, the first kind of error concerns the risk of rejecting a mixture although its homogeneity satisfies requirements, while the second kind of error concerns the risk of accepting a mixture although its homogeneity is insufficient. It is shown that barriers can be introduced for both kinds of error, and how to do this. Both the sample size and the limits of the acceptance range for the sample variance are thus laid down. If no decision is to be made concerning acceptance or rejection of a given mixture, but information is merely required about the mixing quality after a given time then this is accomplished by statement of confidence intervals.
Energieintegration in der thermischen Verfahrenstechnik
Authors: Kaibel Gerd
Published: December 2004

Energetic integration in thermal process engineering. During recent years thermal processes could be considerably improved with respect to their energy demand. Increased use of process heat led to a reduction of production related energy consumption. This article shows that the use of heat integration analysis and exergetic analysis is a promising method for intensive use of the existing potential of energy savings.
Verkleinerung verfahrenstechnischer Versuchsanlagen — was ist erreichbar?
Authors: Maier Siegfried , Kaibel Gerd
Published: December 2004

Scale‐down of chemical engineering pilot plant – what is attainable? The use of fully automated experimental laboratory‐scale plantoffer interesting possibilities for assessment of the economic operation and technical feasibility of new or modified processes. An important condition for the success of this kind of experimental approach is the availability of miniaturized equipment, machines, and sensors. The goal of such experimental plant can be both the process engineering development of individual process steps and also integrated running to model complete processes. Moreover, questions of scale‐up can be studied and typical quantities can be provided. The state of the art is reported with the aid of selected examples of equipment and mechanical components and measurement and control units.
Zur Entwicklungsgeschichte des Chemieingenieurwesens
Authors: Krug Klaus
Published: December 2004

Development of chemical engineering – A survey. This article describes the scientific and technological origins of chemical engineering and the concept of chemical technology. The paradigm of unit operations was the result of mass production, continuous and catalytic processes, and knowledge of physical chemistry. The evolution of theory and the institutionalization of chemical engineering are described as constitutive elements.
Altlastensanierung in der Bundesrepublik Deutschland
Authors: Thomé‐Kozmiensky Karl J.
Published: December 2004

Contaminated site clean‐up in the Federal Republic of Germany. Contaminated site clean‐up will be one of the most extensive and expensive tasks of coming decades. The present contribution first surveys the different views of what constitutes a contaminated site, as held by different authors and different government agencies. The extent of such contamination is then estimated and various processes for its disposal presented. The various clean‐up methods are compared from a technical and a financial standpoint. The state of the art and those areas in which research is called for are indicated.
Nickelhaltige Legierungen und Sonderedelstähle in der Verfahrenstechnik
Authors: Herda Wilfried R. , Rockel Manfred
Published: December 2004

Nickel alloys and special steels. A survey of the main classical alloys for process engineering is followed by an account of the potential uses of modern special stainless steels and nickel‐based alloys in economic plant construction. Examples are given to illustrate these applications.
Elektrochemische Umwelttechnik
Authors: Kreysa Gerhard
Published: December 2004

Electrochemical processes in environmental protection.Electrochemical processes can contribute considerably to environmental protection by means of waste purification processes and production integrated waste minimization. In the field of waste purification, electrochemical gas purification, purification of metal containing waste waters, and the electrolytic decomposition of neutral salt solutions will be illustrated by examples. As examples of production‐integrated environmental protection, this article considers fluidized bed electrolysis, membrane process for alkali chloride electrolysis, and electroreduction of dichloroacetic acid.
Wertewandel: Technikdarstellung in den Medien und Technikverständnis der Bevölkerung
Authors: Kepplinger Hans Mathias
Published: December 2004

Shifting values: Presentation of technology in the media and popular understanding of technology. The leading dailies and weeklies in the Federal Republic presented technology very positively in the mid‐sixties and very negatively in the mid‐eighties. More or less, this is true for all types of technology. Contrary to a widespread belief, the revaluation of technology already started at the end of the sixties. This, however, was not recognized at first because technology was only rarely covered in the press. There was no relationship worth mentioning between the presentation of consequences of technology and real developments. Therefore, the changes in presentation cannot be explained by changes in the reality presented. They are rather caused by changes in the journalists' perceptions of technology.
Die Absicherung von Druckbehältern mit den Mitteln der Meß‐ und Regeltechnik — eine Alternative zur Druckentlastung
Authors: Molter Ernst , Schoft Helmut
Published: December 2004

Safety of pressure vessels by means of measurement and control engineering – an alternative to pressure release. The practice of safety engineering shows that pressure release devices are appropriate or reasonable for only a small portion of the reactions requiring safety assurance measures. One reason is that there is not always an unequivocal relationship between pressure and the factors temperature and concentration which influence the reaction rate. Such a relationship is necessary for reliable pressure release. In addition, environmental protection requires that vapours and liquids leaving the reactor be condensed and collected. Devices used in process control engineering represent alternatives to pressure release systems. They are intended to prevent systems from reaching impermissible operating states. However, this requires very accurate process analysis, for any unrecognized deviation from the correct value of a safety‐relevant process variable could make a safety concept based solely on process control engineering ineffective.
Feststoffbildung durch Kristallisation und Fällung
Authors: Gösele Walter , Egel‐Hess Wolfgang , Wintermantel Klaus , Faulhaber Friedrich Richard , Mersmann Alfons
Published: December 2004

Formation of solids by crystallization and precipitation. Formation of solids from solutions can take place by crystallization or precipitation. The principal factor is the relationship between solubility and supersaturation. In crystallization, the solubility of the crystallising substance is so high that the formation of solids occurs largely in the metastable zone in the immediate vicinity of the solubility limits. Crystal growth and nucleation are functions of supersaturation. If a high supersaturation is required at low substance‐specific growth rates for an adequate crystal growth, high nucleation rates and hence small crystals will result. On this basis, the authors present information for the specific design of crystallization processes. In contrast, the solubility of the precipitated product must be very low for precipitation. Direct crystal formation is possible only for substance systems of high solubility. As a rule, however, the precipitated substance is so insoluble that solids are formed via amorphous intermediates. The results of a large number of experiments show the influence of various parameters of the precipitation process on the filtrability of the precipitated product.
Expertensysteme für die Prozeßführung,–Erfahrungen aus dem Verbundprojekt TEX‐I
Authors: Ahrens Wolfgang
Published: December 2004

Expert systems for process control – experience with the TEX‐I project. The paper gives a brief overview of some topics concerned with expert systems technologies in a real‐time environment. After a four‐year‐project the perspectives of the technology are much more realistic, and the promises more or less reduced. What we see is a software‐technology that is hard to use but well suited for complex applications. Unsolved is the problem of knowledge elicitation, the bottelneck of knowledge engineering.