Browsing by Author "Müller-Simon, Hayo"

Now showing 1 - 17 of 17
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    Application of oxygen sensors in industrial glass melting tanks
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Baucke, Friedrich G. K.; Werner, Ralf D.; Müller-Simon, Hayo; Mergler, Kurt Wilhelm
    A comparative study of electrochemical oxygen sensors for glass melts employing zirconia solid electrolytes developed by Schott Glaswerke and by the HVG is reported. The sensors applied in a feeder Channel of a melting tank producing green glass yielded slightly different but reproducible results despite different constructions. The zirconia reference electrodes achieved more than one year active lifetime at 1200°C. Their potentials directly compared over extended periods agreed within less than 3 mV. The potential differences of the platinum measuring electrodes were traced to temperature gradients. Newly installed platinum electrodes show "induction periods" caused by convectional and diffusional equilibration of adhering surface with bulk melt. Unexpected sudden oxygen inhomogeneities of the melt were detected and explained.
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    Electrochemical measurements of oxygen activity of glass melts in glass melting furnaces
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1988) Müller-Simon, Hayo; Mergler, Kurt W.
    The electrochemical determination of the oxygen activity of a glass melt by a stabilized ZrO2 sensor was established as an online measurement in a working chamber and a feeder channel. A method is described to take the temperature difference between the sensor's electrodes into account. In green glass a correlation between the oxygen activity and Fe2+/Fetot ratio, in amber glass a correlation between oxygen activity and Cr2O3 content are found.
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    Electron exchange reactions between polyvalent elements in soda-lime-silica and sodium borate glasses
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Müller-Simon, Hayo
    In oxidic glasses the redox State of polyvalent elements is determined by the oxygen partial pressure with which the melt is in equilibrium. However, if a second polyvalent element is introduced the redox ratios at a given oxygen pardal pressure change for both elements. This interaction is interpreted in terms of electron exchange reactions during cooling. The direcdon of the electron exchange and the amount of exchanged electrons are calculated from the Standard reaction enthalpy and Standard reaction entropy of the involved polyvalent elements. Oxygen balance calculations are carried out based on literature data available for iron/chromium and iron/manganese interaction in soda-lime-silic a glasses and cerium/manganese interaction in sodium borate glasses. The iron/ chromium and iron/manganese interaction fmishes already at high temperatures. In that case the amount of exchanged electrons can be calculated from stoichiometric considerations. The cerium/manganese couple shows a typical freezing-in behavior in sodium borate glass during cooling. The freezing-in temperature can be associated with the distance of the interacting ions.
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    Investigations into the existence of hexavalent chromium in industrial glasses
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Dusdorf, Wolfgang; Müller-Simon, Hayo
    In several melting experiments the existence of hexavalent chromium in soda-lime-silica glasses depending on the oxidation conditions and the presence of iron have been investigated by means of a recently proposed wet chemical analysis procedure. The observed dependence of the concentraüon of hexavalent chromium on the iron content can be explained by means of an electron exchange between iron and chromium during cooling. The results have been applied to the conditions of industrial glass melting. Under sufficiently reducing conditions and high portions of iron the existence of hexavalent chromium can be excluded. These conditions are fulfilled for all commercial container glasses investigated.
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    On the interaction between oxygen, iron and sulfur in industrial glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Müller-Simon, Hayo
    The oxidation state of iron in industrially molten glasses has been investigated in the cold glass and related to the oxygen activity in the glass melt. The prediction of the oxidation state of iron in the cold glass from the measured oxygen activity in the glass melt is disturbed in such a way that in oxidized molten glasses the Fe²⁺ content and in amber glasses the Fe³⁺ content increase during cooling. This behavior can be explained by an interaction due to the oxidation reactions of sulfur known from the literature during cooling. The reaction constants result in electrochemical standard potentials which agree with voltammetric studies.
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    On-line determination of the iron concentration in industrial amber glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1995) Müller-Simon, Hayo; Mergler, Kurt Wilhelm
    A sensor has been developed in order to measure the concentration of polyvalent elements on-hne in industrial glass melts. The sensor has been tested on iron in an amber glass melt. A method has been developed in order to determine the area of the measuring electrode, which can change due to glass level variation. The accuracy of the iron determination by means of the voltammetric sensor has been found half the accuracy of x-ray fluorescence analysis.
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    Oxygen balance in sulfur-containing glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1998) Müller-Simon, Hayo
    In sulfur-containing glasses the Fe²⁺/Fe³⁺ ratio at a given oxygen partial pressure shows a considerable shift compared to glasses without sulfur. This effect is caused by an electron exchange and governs the redox behavior of industrial glass melts at fming temperature. The electron exchange is formulated by a thermodynamic approach which can quantitatively describe the redox reactions between melting temperature and room temperature in flint glasses. In amber and green glasses this dependence is superimposed by the dissolution of SO₂-containing bubbles, which results in an additional shift of the oxygen partial pressure in the direction of the sulfur solubility minimum during cooling. From this shift the maximum solubility of sulfite in soda-lime-sihca glass melts can be estimated to be about 0.025 wt% SO₃. Resorption curves of sulfite sulfur in the melt describe the refining quahty. They can serve as a tool for improving the secondary refining in sulfur-containing industrial glass melts.
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    Practical strength of glass containers : Part 1. Influence of the type of defect
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Müller-Simon, Hayo; Wagner, Jörg; Lenhart, Armin
    The practical strength of container glass depends not only on the stress distribution at the surface, but also on the type and distribution of surface defects. After the elimination of the influence of the container shape by means of finite element methods, different types of defect show a different behaviour in the Weibull plot. Especially seeds and blisters are shown to be twice as dangerous as inhomogeneides caused by handling materials. The accuracy of the stress determination is limited, thus, an identification of different types of inhomogeneities from the Weibull plot is not possible under the present conditions.
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    Practical strength of glass containers. Part 2. Influence of handling
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Wagner, Jörg; Müller-Simon, Hayo; Lenhart, Armin
    The practical strength of container glass depends not only on the stress distribution at the surface, but also on the type and distribution of surface defects. After the elimination of the influence of the container shape by means of finite element methods, different types of defect show a different behaviour in the Weibull plot. This behaviour can be used to compare different handling materials. The materials used at the cold end cause no measurable weakening of the strength. A special type of defect could be associated with the transfer conveyour belt. Carbon and brass were compared as deadplate materials without finding a specific influence on the container strength.
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    Redox behavior of selenium in industrial soda-lime-silica glasses
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2001) Müller-Simon, Hayo; Bauer, Johannes; Baumann, Patrick
    A thermodynamic model for the calculation of the redox distributions of polyvalent elements which is based on the balance of chemically bonded oxygen in glass melts has been applied to the redox reactions of selenium. A set of reliable thermodynamic data of the selenium oxidation reactions has been derived using results of electrochemical, optical and wet-chemical investigations. Calculation results showed that selenium is reduced during cooling by iron as well as by sulfur. Due to the small selenium/sulfur ratio in selenium-decolorized flint glasses under industrial conditions selenium is completely reduced to the selenide state. Obviously, in industrially melted flint glasses selenium decolorization is not provided by the pink color of elemental selenium as assumed so far but by the amber color of iron selenide, which is supported by the fact that selenium decolorization always causes an additional yellow tint besides the required red tint and a considerable shift of the UV edge to larger wavelengths.
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    Selenium flow in the melting of flint glass Containers
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Müller-Simon, Hayo; Kirchner, Ulrich
    [no abstract available]
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    Sensor for oxygen activity measurements in glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1991) Müller-Simon, Hayo; Mergler, Kurt W.
    Traditional oxygen activity measurement in glass melts is based on Y2O3-stabilized ZrO2 which, in continuous use in the glassworks, is subjected to considerable wear. The present paper describes an oxygen sensor that is not equipped with wear parts. The new sensor is far less sensitive to temperature gradients in the surrounding area than ZrO2 sensors; the oxygen measurement, however, is greatly disturbed at direct flame irradiation.
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    Strength optimization of glass containers by the finite element method
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1988) Müller-Simon, Hayo; Barklage-Hilgefort, Hansjürgen
    A finite element program to calculate the wall stresses of container glass with respect to axial loads and internal pressure loads has been installed in a microcomputer. The stress calculations are based on a modified shell element. The efficiency of this element type as well as the working properties of the finite element program were tested. Sample bottles and the corresponding bursting pressure data were available for this investigation. From these data, maximum permissible wall stresses were calculated with the finite element program. The results were found to be in the same range as those stated in the literature. The finite element program gives a fast and sufficiently accurate prediction of the influence of changes in glass container outline or glass distribution by calculation.
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    Temperature dependence of amber color generation in soda-lime-silica glass
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2000) Müller-Simon, Hayo
    Recently, spectroscopic investigations in the UV-VIS range showed that the amber chromophore in soda-lime-silica glass vanishes with increasing temperature. Oxygen balance calculations have been carried out in order to explain this behavior thermodynamically. The calculations yield that, based on the available standard reaction enthalpies and standard reaction entropies, the product of the ferric and sulfide concentrations decreases with increasing temperature.
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    Temperature dependence of the redox State of iron and sulfur in amber glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Müller-Simon, Hayo
    In industrially melted amber glass the logarithm [Fe²⁺]/[Fe³⁺] shows no linear dependence on the logarithm of oxygen partial pressure. This nonlinearity is due to the interaction between iron and sulfur which can be described by means of a simple oxygen balance model. The change of chemically dissolved oxygen as a function of the oxygen partial pressure depends on the redox State and has a minimum at intermediate oxygen partial pressures. In this region small variations of the reducing additions in the batch cause large variations of the oxygen partial pressure.
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    Vergleich verschiedener Meßverfahren zur Bestimmung des Abgasqueraustausches in Glasschmelzwannen
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1986) Müller-Simon, Hayo; Barklage-Hilgefort, Hansjürgen; Mergler, Kurt Wilhelm
    Die aus Helium-Impfmessungen ermittelte Queraustauschmatrix ist relativ unempfindhch gegenüber kleineren Veränderungen der Brennerbeaufschlagung. Ist die Queraustauschmatrix einmal bestimmt, lassen sich die Abgasvolumenströme in den einzelnen Kammern aus den Brennstoff- und Verbrennungsluftmengen gut berechnen. Eine Abhängigkeit zwischen den mit der Helium-Impfmessung gemessenen Austauschströmen und den Austauschströmen, die aus der Druckverteilung im Oberofen und den Brennerimpulsen errechnet wurden, konnte nicht eindeutig nachgewiesen werden. Mit dem Prinzip des Prandtlschen Staurohrs wurde der Zusammenhang zwischen Staudruck im Brennerhals und Strömungsgeschwindigkeiten untersucht. Eine Abhängigkeit konnte auch mit einer einfachen Meßanordnung gefunden werden.
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    Voltammetric sensor for glass tanks
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1992) Zink, Marianne; Rüssel, Christian; Müller-Simon, Hayo; Mergler, Kurt Wilhelm
    Voltammetric methods formerly solely applied to laboratory experiments were used for measurements in a green glass tank. The applied experimental parameters had to be restricted to step times of 20 ms or more using square-wave voltammetry and frequencies of 35 s^-1 or lower using alternating current voltammetry. Within these limitations, the voltammetric sensor used was fairly suitable for these measurements. The adjustment of the electrode area, i.e. the dip-in length of the electrodes, could easily be controlled by conductivity measurements between the electrodes. The obtained voltammetric curves were fairly similar to those obtained from laboratory experiments and were predominantly affected by the iron concentration of the glass melt.