Neuere Erkenntnisse und Anwendungen bei der elektrischen Abscheidung von Stäuben und Nebeltröpfchen

New insights and applications in the electrostatic precipitation of dusts and mists. The introduction deals with the basic design, the mode of operation, and the fields of application of dry and wet type electrostatic precipitators. A few important parameters which influence the migration velocity are discussed. Contrary to what the classical theory states, greater passage widths lead to higher migration velocities of the particles and thus to a higher specific efficiency. The methods for conditioning flue gases of power stations are considered, as are the experimental results obtained in an industrial-scale SO₃ conditioning plant. A new field of application is seen in the steel industry through the use of a dry type electrostatic precipitator of special design. New plastic precipitator developments for the chemical industry are discussed, and the articles closes with an account of the efforts invested in developing hot gas precipitators for higher temperatures and pressures in connection with the introduction of new power station concepts.     

Abscheidung hochohmiger Stäube in einem Elektrofilter mit niederfrequenter Wechselspannung

Due to the occurrence of back corona, the separation of particles with high electrical resistivity in electrostatic precipitators (ESPs) is difficult. In this case, the power consumption of the ESPs is significantly increased, and unacceptably high particulate emissions occur. Here, a novel approach for the separation of highly resistive dusts with ESPs is described. The effective electrical resistance of the dust layer can be modified by the use of low‐frequency AC voltage, which significantly improves the separation rates. The new method was tested with various highly resistive dusts in a wire‐tube ESP.     

Kostenoptimierung von Verbundfolien unter Berücksichtigung von Gasdurchlässigkeit und Steifigkeit

Optimization of the Cost of Wrapping Materials with Emphasis on the Permeability of Gases and the Stiffness A procedure is described for calculating optimum thicknesses of the individual layers of multi-layer wrapping foils that are used for packaging semi-solid goods. With a suitable combination of materials in various layers, the wrapping foil represents an optimum as regards the cost of raw material, the desired stiffness and gas permeability. Apart from the cost of raw material the E-modules, the permeability coefficients and the density of the materials involved have to be taken into account for the calculations. The validity of the equations employed in the procedure for optimization is demonstrated experimentally on an example of a wrapping material that consists of three layers. Predictability of this procedure is discussed on several examples.     

Analyse von Cremes und Lotionen unter besonderer Berücksichtigung von Sonnenschutzpräparaten

Analysis of Creams and Lotions with Respect to Sun Protecting Products At first the analysis of creams and lotions by saponification is described. The unsaponifiable and the saponifiable matter as well as the acid aqueous fraction are further analized by GC. Without saponification the separation can be done by HPLC using columns with silica gel as stationary and n-hex-ane/ethylacetate (97:3) as liquid phase. Hydrocarbons, fatty acid esters, triglycerides and fatty alcohols can be separated from each other and from emulsifiers on basis of nonionic ethoxylated surfactants and quantitatively determined. By the same method also the uv-absorbers of water free or emulsified suntan preparations can be identified and determined. This can be done in one working operation, if a uv/vis-spectrophotometer and a differential refractometer are arranged one after another. For the separation and determination of the uv-absorbers of suntan preparations which are water soluble also a HPLC method is used but with reversed phase column and methanol/water as eluens.     

Modellierung der anaeroben Bioabfallvergärung unter Berücksichtigung von syntrophen Propionat‐oxidierenden Bakterien

Anaerobic digestion of biowaste allows a sustainable production of bioenergy and reduces environmental burden. The anaerobic digestion phase was modeled with Anaerobic Digestion Model No. 1 (ADM1), which was extended to include three genera of propionate‐oxidizing bacteria and two routes of propionate degradation, namely methyl‐malonyl CoA and C6‐dismutation pathway. Kinetic parameters for anaerobic propionate oxidation were determined with defined tricultures of the three propionate‐oxidizing genera together with hydrogenotrophic and acetotrophic methanogens and implemented into ADM1, resulting in the improved model ADM1xpro.     

Gewinnung von Euphorbiaöl unter besonderer Berücksichtigung der Abpreßbedingungen

Extraction of Euphorbia lathyris Oil by Pressing The seed of Euphorbia lathyris (caper spurge) seems to be interesting with respect to its high oil content (ca. 50% with more than 80% oleic acid). Like most other oilseeds considered to be “Renewable Raw Materials” Euphorbia lathyris is also cultivated in low quantities and, therefore, the oil of these seeds has to be extracted in small plants. When optimizing the pressing process of small plants the pre-treatment of seed and the oil processing have to be taken into consideration. With regard to the oil yield and the solids in the oil it is convenient to preheat the seed. The solids in the oil can be removed by sedimentation and filtration. An oil pressing plant is presented, which is built up according to a conception of the DIL and being equipped with a control unit for continuous operation.     

Abbildung von Oberflächen mit dem Rasterelektronenmikroskop unter besonderer Berücksichtigung der Abbauvorgänge bei der Bewitterung TiO2-pigmentierter Anstrichfilme

Studies on Surfaces Using Scanning Electron Microscope with Special Consideration of Degradation Processes During the Weathering of Paint Films Containing TiO₂-Pigment Fundamentals of scanning electron microscopy and the accessory instruments required for differentiating materials and for analysis are discussed. Using the scanning electron microscope a concept on the chalking of paint films containing TiO₂ as pigment was verified. It was found that in the course of degradation of the binding agent the particles of TiO₂ are not completely exposed, but instead, they adhere to the paint film via ?binder socket”?. The concepts derived from these studies permit the interpretation various phenomena that are observed in paint films subjected to weathering.