Naßoxidation — Ein Beitrag zum Stand der Technik

Wet air oxidation – Present-day technology . Wet air oxidation is a process of flameless “incineration”, especially of organic compounds, in an aqueous phase with air or other oxidants at relatively high temperatures and pressures. Existing applications such as the sanitizing of sewage sludge, processing of sludges from pulp production, and regeneration of activated charcoal are described. At present, waste water purification by wet air oxidation is being propagated. Difficult degradation of some pollutants enforces the use of temperatures up to 330°C and pressures up to 250 bar. The high investment costs for such plants, which require materials like titanium or hastelloy to handle corrosive wastes, often result in higher operating costs than with other methods, in spite of low energy consumption. Once the effectiveness of existing plants has been proved, especially regarding corrosion problems, rising demands for waste water purification may render wet air oxidation increasingly important.     

Zyklonabscheider zum Trennen von Gas/Feststoff-Strömungen

Cyclone separators for separation of gas/solids flow systems . Cyclones are used for separation of particles of solids from gas flow. Although cyclones have been in industrial use for nearly a century, it is still impossible to completely calculate the flow processes involved. This contribution deals with the theory of the separation process with separation behaviour, limiting particle size, generation of twist, and pressure drop. The article describes optimization of the cyclone by aerodynamic calculations with the separation performance, energy requirement, and investment costs as parameters. The separation performance and the energy requirements of cyclones are largely determined by the mode of construction and the operating conditions. Cyclones used industrially are discussed.     

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.     

Ein Beitrag zur Bestimmung der Höppler-Härte

A Contribution to Determine the Hoeppler-Hardness It was investigated in which limits the Konstistometer (according to Hoeppler) with measuring unit IV (steel cone) manufactured by Haake GmbH, Karlsruhe, is suitable for measuring the hardness of waxes. A load of 15 N (1500 p) gave a depth of penetration, which was sufficient to keep the fault range below ± 5%. The resulting penetration craters were checked for cracks and wall formation by electron scanning microscopy. A strong dependence of Hoeppler hardness from the crystal structure of the wax was observed in some cases.     

Ein Beitrag zur Dünnschichtchromatographie von Aniontensiden

A Contribution to the Thin-Layer Chromatography of Anionic Surfactants Anionic surfactants and some nonionic surfactants are chromatographed on silica gel plates with tetrahydrofuran + acetone (1 + 9 v/v) as solvent, sprayed with a solution of pinacryptol yellow and examinated under ultraviolet light at 366 nm. The surfactants appear as coloured fluorescent spots on a pale blue background. The relative air humidity has a major influence, i. e. the water content of the silica gel layer, which can be fixed by preconditioning of the plate by the vapour of the solvent. A complete separation of alkane-/olefinesulfonate, cumene/xylene-/toluenesulfonate, alkylbenzenesulfonate, α-sulfofatty acid methylester, fatty alcohol sulfate, fatty alcohol ether sulfate, fatty acid diethanolamide, fatty acid monoethanolamide and soap can be attained. Thin-layer chromatograms of a range of mixtures fatty alcohol sulfate/fatty alcohol ether sulfate and several fatty alcohol ether sulfates with increasing content of ethylen oxide are discussed.     

Ein Beitrag zur Prüfung von Weichspülmitteln

A Contribution on the Examination of Rinsing Agents Containing Softeners Three determinations are important for the examination of the action of rinsing agents on laundry: 1. assay of the texture of textiles treated with rinsing agents containing softeners; 2. water uptake by textiles treated as above; and 3. antistatic action of rinsing agents containing softeners on synthetic and mixed fabrics. Various methods have been employed for the aforesaid determinations, and they have been compared using three well known commercial rinsing agents. The investigations have revealed that some of these methods yield good results that agree with practical evaluations, whereas several other methods are unsatisfactory. Therefore only certain methods should be chosen for such evaluations, if one aims at an objective assessment of rinsing agents.     

Beitrag zur Bewertung von Stoffaustauschböden

Assessment of fractionation trays. To assess fractionation trays from a process engineering point of view, the following need to be defined: the loading dependent separation efficiency and pressure drop, together with the loading range and the highest possible loadings at which an acceptable efficiency is reached. As an example, one of the trays used successfully in industry for many years which represents the latest in tray technology was tested together with a new development, the Dualflex tray. The results of the comparison tests show that: Based on the process characteristics of the Dualflex tray, it can be classed as a high capacity tray for thermal fractionation processes. With high loadings it has a good efficiency and correspondingly low pressure drop. Because it uses the dualflow principle it is capable of bearing significantly higher loads than conventional cross-flow trays. For example, Dualflex trays can be installed in column revamps to give an advantageous increase in capacity, or in new plants where more than 30% of the column cross-section can be saved compared with conventional fractionation trays. The above constructive and technological advantages combined with the optimal design of the Dualflex tray lead to a considerable reduction in product hold-up time when compared with traditional crossflow trays with downcomers. For example, this new tray can be used advantageously with the fractionation of thermally sensitive material systems. It would also be possible to use the Dualflex tray for the vacuum distillation (approx. 10 mbar) of fatty acid alcohol and esters (up to C12) with low reflux ratios (3:5) in columns which are fitted out with thin-film evaporators.     

Ein modell zur quantitativen beschreibung der morphogenesis von PVC-S,III. Modellierung der inneren morphologie — parameterstudien

In this part properties and efficiency of the developed model^1,2 are discussed. A variation of the parameters shows that vigorous effects are caused by the effective aggregation. All calculations show that at low conversion there are little temporal steps between the sequential aggregation steps. In the range of 5% to 20% conversion the velocity of aggregation decreases and the aggregative stability agrees with experiences given in the literature. It is shown that the calculated results are in agreement with the experimental results and therefore the presented model is a suitable possibility to describe the formation of some PVC-morphology properties.