Fortschritte auf dem Gebiet der Alkalichlorid-Elektrolyse

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.     

Fortschritte auf dem Gebiet der Flüssig/Flüssig-Extraktion

Progress in liquid/liquid extraction . Liquid/liquid extraction continues to increase in importance. Classical areas of application, such as aromatic chemistry, hydrometallurgy, and reprocessing of spent nuclear fuels are being supplemented by new uses in biotechnology, in pharmaceutical production, and in water treatment. This upswing would be unthinkable without intensified R & D in chemistry and process engineering. Deeper knowledge of the physical chemistry of solvents permits purposeful choice of solvents for special separation tasks, advances in engineering elucidation of flow and mass transfer in proven and in newly designed extractors creates a basis for calculation or at least assessment criteria for the choice and operating behaviour of equipment. Yet much remains to be clarified. This article describes the current state of the art in the analysis of flow and mass transfer in countercurrent gravity feed columns with and without pulsation or agitator energy and in centrifugal extractors. A brief look at new designs demonstrates that scientific knowledge gave birth to the new ideas expressed therein.     

Fortschritte in der Adsorptionstechnologie

The high purchasing price of organic solvents has stimulated interest in their recovery from emissions. While conventional adsorption units for recovery of monosolvents have been in industrial use for some 70 years, it has hitherto proved impossible to costeffectively desorb solvent fractions sufficiently pure for direct use in the case of emissions of mixtures. The solvent mixtures obtained by desorption had to be separated in expensive rectification steps, with the high costs thus precluding widespread use of adsorption for recovery projects in the chemical and printing industries. After conclusion of development work performed in the USA and Germany over a period of 10 years, it is now possible to control the adsorption steps in such a way that the purities necessary for reutilisation of the individual solvent fractions can be attained without the aid of rectification steps.     

Fortschritte in der Welterzeugung von Rapssaaten

Progress in the World Production of Rapeseed In 1982, the acreage of rapeseed cultivation in the EEC for the first time exceeded the threshold of the one million hectares. Similar expansion of rapeseed production occurred worldwide; but in many countries the increasing interest was directed to other Brassica species, too. In three of these (B. napus, B. campestris, B. juncea) socalled 00-forms, low in erucic acid and glucosinolate content, are now available for breeding; in the further cultivable Brassica species the same quality characters undoubtedly could be obtained from corresponding screening. Progress can also be noted with respect to an improvement of the contents of polyenoic fatty acids in the rapeseed oil. Historically every introduction of a new quality trait led to reduced yields; but always after a few years selection had been effective to give higher yields than before. In future another yield increase can be expected from the development of hybrid varieties. These require a broad genetic variability; such was recently made available by resyntheses of B. napus (n =19) from its ancestral species B. oleracea (n =9) and B. campestris (n =10). Finally, high grades of disease resistance are required because of the present density of rapeseed cultivation. In this connexion, effective resistance against Phoma lingam and Sclerotinia sclerotiorum has been evolved in high yielding varieties in only a few years by simple selection.     

Fortschritte in der Zerstäubungstrocknungs-Technologie

Progress in the technology of spray drying . Stringent quality demands on spray-dried goods have led to increasing use of nozzle spray dryers. In contrast to disk spray dryers, nozzle dryers yield microgranules and low-dust products directly. Although the process of nozzle spray drying is over 50 years old, the volume of available calculation material necessary for general application is sparse and limited mainly to special products or problems. This article presents new advances in the technology of nozzle spray dryers. An analytical formulation of the drying of a drop within the first drying phase decisive for granulation constitutes the basis of the general applicability of the fresh insights gained.     

Fortschritte bei der Modellierung von Festbettreaktoren

Progress in the modeling of fixed bed reactors. Recent work on the modeling of catalytic fixed bed reactors have led to more realistic mathematical models and to a better understanding of problems connected with modeling. Nowadays standard routine computer programs are available for use in the design (and analysis) of catalytic fixed bed reactors for very complex reaction systems. The influence of bed structure on transport parameters was illustrated by experimental determination of axial and radial concentration and temperature distribution. Moreover the problem of multicomponent diffusion coupled with complex reactions in porous catalysts has been solved and can be included in the reactor model. However, the practical application of possible reactor models is limited by the availability of transport parameters for fixed beds.     

Fortschritte in der Gewinnung und Verarbeitung von Pflanzenlecithinen

Progress in Production and Processing of Vegetable Lecithines Production and processing of vegetable lecithines, won as secondary products of edible oil production, have only very seldom been the subject of publications in German literature during the last decades. Since 1950 remarkable improvements have been achieved in this field. In detail they concern the hydratation methods, the fractionation procedures which are worked out to separate neutral lipids, unwelcome phosphatides and oligosaccharides as well chemical and enzymatical reactions by which the emulsifiability and the dispersing power of the lecithine preparations can be improved. The present report bases on scientific publications and patent literature. It considers beyond that the results obtained in the author's laboratory.