Freies Glycerin und Gesamtglycerin-Gehalt in Monoglyceriden und in Partialester-Gemischen. Ein Vergleich der enzymatischen Glycerin-Bestimmung mit chemischen Methoden

Free and Total Glycerol Content of Monoglycerides and Mixtures of Partial Esters. A Comparison of the Enzymatic Glycerol Estimation with Chemical Methods The free and bound glycerol content of water-soluble and/or strongly emulsifying as well as of water-insoluble monoglycerides was determined enzymatically. The values thus observed were compared with those obtained by chemical methods. Free glycerol could be determined in all the samples only with the help of the enzymatic method. A good agreement between the values obtained by the two methods was found only in the determination of total glycerol in water-insoluble monoglycerides. In the enzymatic procedure for glycerol determination, the relative standard deviation for various weighings lies between 0.86 and 1.26%; taking P = 95%, x_rel. amounts to 1.9–2.8%. Lambert-Beer's law is valid for a wide range.     

Koaleszenzprobleme in chemischen Prozessen

Coalescence problems in chemical processes . Separation of liquid/liquid dispersions is a process step which often gives rise to considerable difficulties on an industrial scale. A number of selected examples taken from chemical processes demonstrates where phase separations occur, the consequences they may have, and what industrially practicable methods are available for their solution. The problem analysis presented starts from the mechanism of generation of the dispersion and leads to a qualitative characterization of the various coalescence problems without presuming any knowledge of the droplet spectrum. This procedure acquires important knowledge from an assessment of prior process steps. Measures for improvement are deduced from the causes of poor phase separation: modification of physical properties, change of dispersion, use of mechanical separation aids (packings, coalescing filters), application of an electrical field, centrifuges and hydrocyclones, coalescence-promoting chemical additives. Industrially applicable methods are reported for design of equipment for implementation of these approaches.     

Prognosen in der chemischen Technik

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.     

Produktionslogistik in der chemischen Industrie

Logistics in the manufacture of chemical products. This survery covers the fields of location analysis, organization of operational material flow, and materials management, all of which are interlocked with each other. Logistics problems with location analysis lie in the area of infrastructure, procurement, and distribution. The organization of the operational material flow has to be based on a closed concept, taking simultanously into consideration interests of production techniques and of logistics. Special attention has to be paid to the reciprocal effect of plant and storage capacity. With complex production structures simulation models should be used, including a statistical model of the market demands, systematic variation of material flows, and grouping of technical equipment. Target is a minimization of total cost. For market oriented operation of complex productions, integrated materials management systems have to be employed. The systems supply a transparent material flow starting from the market demands via the control of production up to the procurement of raw materials.     

Reaktorintegrierter Umweltschutz in der chemischen Produktion

In the series of environmental protection measures avoidance-utilisation-disposal the greatest priority in the chemical industry is given to the first, particularly since it is the chemical reaction which predetermines the nature and extent of subsequent work-up steps and the environmental burden. This reactor-integrated environmental protection leads to a process reappraisal which is divided into searches for alternative synthetic routes, reactants, reaction media, and catalysts. However, one of the principal tasks concerns reexamination of the thermodynamics and kinetics, not only to ensure optimised concentration and temperature control but also to examine the possibility of integrating separation operations during the course of reaction with the aim of shifting equilibria.     

Quantitative Risikoanalysen in der chemischen Industrie

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

Umweltfreundlichere Produktionsverfahren in der chemischen Industrie

Environmentally more acceptable processes in the chemical industrys. From its very beginning the chemical industry has always made every effort to cut the consumption of raw materials and energy in its processes and to diminish the release of by-products and waste streams into the environment. These efforts at technically improving the various processes are presently being intensified by economical and political pressures of rising raw material costs and the rising costs of releasing harmful substances into the environment. Ways of reducing these influences on the environment by chemical processes and of improving process economics will be reported from the experience of Bayer AG. The examples show that it is possible to combine the indispensable with the practicable, and that in this way the burden on the environment can be kept as low as may be consistent with the image of the industrial society.     

Radioaktive Indikatormethode in der chemischen Verfahrenstechnik

The radioactive tracer method in the chemical industry. In the chemical industry the radioactive tracer method has become a method of analysis with a variety of applications, which range from determining traces of biologically active substances to process analysis in production plants. Process analysis, for instance the determination of residence-time distributions or of intermingling of streams of different substances, can be carried out under widely varying operating conditions. If the streams of material are labelled with gamma-ray emitters the distribution of the tracers can be determined by means of detectors outside the plant. To demonstrate the possible applications of the method to process analysis, measurements in three different plants are described. Exhaust gases were labelled with Ar-41 to determine the residence-time distribution in plant for the combustion of waste residues consisting of a rotary tube furnace, an afterburn chamber, and a waste-heat boiler. The waste water entering the activation tank of sewage-treatment plant was labelled with Na-24 to determine its residence-time distribution. Individual particles labelled with Mn-56 were used to investigate mixing of the powder in the stirred-bed reactor of a polypropylene plant. The knowledge gained from these measurements has contributed to optimization of existing and planned plant.     

Der Verfahrensingenieur in der chemischen Industrie

The Process Engineer in the Chemical Industry . Tasks and problems are dealt with which the process engineer in the chemical industry has to perform or solve together with scientists. At present the problems are caused primarily by the rapid price rises for power and raw materials which have occurred in the past few years, and by the increased efforts on environmental protection. Future problems which are already becoming clearly discernible concern the development of resources which will be available over the long term to supply raw materials and power and also food for the rapidly growing world population. The chemical industry must make a decisive contribution to this development, and we must decide now on the direction it is to take. The process engineer has a key role to play in the accomplishment of these manifold and difficult tasks. This article describes the requirements he must satisfy and the conclusions which must be drawn in regard to his education and training.