Anwendung des Temperatur-Meßsystems QuaT in der Prozeßmeßtechnik

Application of the QuaT temperature measuring system in process measurement engineering. Resistance thermometers and thermocouples are today's standard in industrial electrical temperature-measurement techniques. Their weaknesses, which were not so important, have become obvious with the advanced application of digital data loggers and data control units. These weaknesses include: uncertainty wether such a measuring line is predictable; the transmitter has to be defined with regard to the parameter, for each individual application; and transfer of the measured signal from the field to the central unit needs considerable effort. A temperatur measurement system has now been introduced which does not have these disdvantages, because it is using a piezoelectric resonator as a sensor element. Thus signal processing is ?digital”?. Advantages and disadvantages of both kinds of instrumentation are presented. The suitability of the new system, also regarding costs, is confirmed by the results from five industrial test programs.     

Die Anwendung von Prozeßrechnern in der Waschmittelproduktion

The Use of Process Control Computers in the Production of Laundry Detergents Modern laundry detergent production plants require highly sophisticated measuring and controlling systems in order to maintain high and even quality of the products. In addition, the detergent industry is under a very high cost pressure due to market circumstances. It appeared to be efficient to improve the measuring and controlling technology by using process control computers and to come to production methods with lower cost rates. Also, even and safe operation methods are desirable for every production process as well as rapid recognizing and elimination of troubles and early warnings in case of breakdowns. Prerequisites with regard to computer control are a high level of the process equipment and a continuous recording of measuring data, which is very important. The method of operation of the computer control is discussed in general the resulting efficiency is presented. The efficacy can be quantitated with regard to the desired decrease of raw material costs, conservation of energy and saving manpower. The efficiency can not be quantitated with regard to deepening of knowledge of the process, accelerating of the performance of trials, collecting experience for other processes and as prerequisite for a composite system of electronic data processing in the production department.     

Untersuchungen zur Optimierung der Fällfraktionierung von Polymeren

The possibilities for a systematic selection of the conditions for fractional precipitation in polymer/solvent/nonsolvent-systems based on data of the turbidimetric titrations have been tested experimentally. As criticism for the fractionation efficiency the molecular weight distribution of the fractions (determined by ultra-centrifuge) and the uniformity M?_w/M?_n (calculated therefrom) was taken. The successiv- and subfractionation, the dependence of the initial concentration and particularly the influence of the solvent/nonsolvent-system on the fractionation efficiency were investigated. Therefore a simple new method was developed, which allows to arrange systematically different solvent/nonsolvent-systems with few turbidimetric titrations as to be suitable for fractionation. For three selected solvent/non-solvent-systems the correctness of the selection method could be proved experimentally.     

Aktuelle Entwicklungslinien der elektrochemischen Prozeßtechnik

Development trends in electrochemical process engineering . Important electrochemical production processes have recently been crucially modified or newly developed and this opened new horizons for the future of industrial electrochemistry. The thrust of this development is discussed in three selected areas: alkali chloride electrolysis, water electrolysis, and organic electrosynthesis. Important past steps are the invention of the dimensionally stable anodes, the development of the cation exchange membrane and membrane electrolysis, the successful testing of zero gap cells, SPE electrolysis and the economic use of two phase electrolytes. These successes have arisen mainly from an improved knowledge and understanding of the fundamental principles of electrochemical engineering.     

Prozeßentwicklung: Von der Exergieanalyse bis zur EDV-gestützten Optimierung

Process development: From exergy analysis to computer-aided optimisation. In processes in which chemical compositions or states are altered, limiting case analyses based on the first and second laws of thermodynamics are often of use during preliminary process analyses. Since the introduction of computers for process calculations exergy analyses can be carried out in a simple way and weak points in initial designs in the sense of the second law conveniently located. It is also possible to use exergy analyses to make product predictions if transferable practical exergy losses are available from past experience. In low temperature and energy technology the use of suitably defined efficiencies have been of use for many years in eliminating less attractive processing routes and thus reducing the number of possible designs to be investigated. For many decades so-called ?Sum Q/T Diagrams”? have been used in low temperature processing to visualize and improve temperature profiles in heat exchanger networks. Recently technology has been further developed into ?Pinch Technology”?. At the end of process development comes the final detailed optimization. The expensive and time consuming sequential way of working used in the past is being gradually replaced today with equation-oriented simulation and optimization tools such as the OPTISIM program. Expert systems, in principal, offer the chance of supporting the chemical engineer during the initial design of complete and complex processes. However, the experience with such systems to date has shown that a practical solution lies a long way into the future.     

Ein Beitrag zur Temperaturabhängigkeit der Viskosität wäßriger Polyethylenglykollösungen

An automatic falling ball viscosimeter of the Höppler type with pneumatic rotary actuator and electrical time measuring was used to determine the viscosity of aqueous polyethylene oxide solutions between the temperature range of 20 to 80°C. For these investigations polyethylene oxide fractions were used having molecular weights of 600 to 20 000 g/mol. The concentration of the solutions was up to 5 base mol-% of polymers. Parameters according to Eyring- and Vogel-equations were evaluated by the measured viscosity data. This evaluation led to the result, that the parameter T₀ decreased linearly with increasing molecular weight and concentration. The effect was explained by the water-structure-breaking by means of the polymer molecules. The logarithmic intrinsic viscosity in the solutions containing water and polyethylene oxide of a molecular weight of 6 000 g/mol decreased rapidly with the temperature and led to a value of ?8.6 · 10^?3 for d In [η]/dT.     

Anwendung der coulostatischen methode zur bestimmung der doppelschichtkapazität einer bleielektrode

The coulostatic method used in determining the double-layer capacitance of the mercury electrode was applied for measurements on a lead electrode in sodium sulfate solutions. The curves: differential capacitance of the double-layer electrode potential are shown. As a result, the sulfate ions do not adsorb on the lead. The double-layer capacitance values in 10⁻³ N Na₂SO₄ at different potentials of the lead electrode have been calculated.

The theoretical results have been compared with the experimental data. The application of Grahame's model for the double-layer structure in the case of lead electrodes has been confirmed.     

Prozeßführung zur Sicherung reproduzierbarer Qualität in der verfahrenstechnischen Produktion

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.