DD203397A1 - METHOD AND ASSEMBLY FOR DETERMINING THE MELTING BEHAVIOR OF GLASS - Google Patents

Abstract

The invention relates to a method and a Pruefanordnung for determining the melting behavior of glass. The aim is a rational measurement and evaluation of the test procedure. The task is to develop a test method in which the melting process from the batch to the cleared glass is examined over the entire temperature range with respect to melting and leaching behavior and to provide a test arrangement for this method. According to the invention, this is achieved by measuring, automatically detecting and evaluating the voltage drop proportional to the electrical conductivity of the batch or the glass melt during temperature increase at specific time intervals via platinum electrodes immersed in the melt. The test arrangement has two platinum electrodes arranged centrally in a melting vessel and at a certain distance from each other.

Description

-a- 23536

Inventor"

Volker Herrmann Horst Jüptner Achim Wehner

Registered Agent "

VEB Institute Technical Glass Jena Central Office for Property Rights GDR - 6300 ILMENU PO Box 303

IPKi G01N, 27/00

Method and test arrangement for determining the melting behavior of glass

Field of application of the invention}

The invention relates to a method and a test arrangement for determining the melting behavior _v, in particular of the melting and refining behavior of glass.

Characteristic of the known technical solutions!

To investigate the melting and lautering behavior of glass, two different types of processes are known «,

- 2 - "& a " J »

The procedures based on the measurement and evaluation of solid cooled glass samples are made, for example, by counting the number and size of bubbles or striae in glass samples. The purpose of these methods is that the actual melting and lautering behavior should be in the cold state of the glass and not in the glass interest melting and refining, d »h _it occurs in the specific temperature range of the glass _o Furthermore, methods are known which make it possible, directly or indirectly, the Binschmelz- or track lautering of a glass sample at high temperatures. Bs are direct measuring methods are known in which z «B« are examined by a heating or hot table microscope batch samples during melting and refining · For the indirect examination of a glass sample is known to try to use the electrical conductivity to determine the fining behavior «This is the mixture pre-heated until the meltdown in a furnace and then in a device for measuring the specific electrical conductivity at constant temperature using the specific electrical conductivity of a Läuterzeitgewinn determined by comparison with other samples. In addition, it is known to introduce measuring electrodes into the molten glass sample and to measure the electrical resistance change at a certain temperature by means of a measuring apparatus for determining the specific electrical conductivity, whereby statements about the refining behavior of the glass are obtained. Disadvantage of these methods is the pre-melting of the glass samples outside the Meßapparatur® This causes the melting process is interrupted and the part of the melting process that takes place before the investigation in the measuring apparatus can not be used in the determination of the melting behavior

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In addition, both methods are not suitable for glasses with a tendency to foaming. The measurement results determined by the methods are usually not repeatable.

Object of the invention:

The aim of the invention is to provide a method and a test arrangement for determining the melting behavior of glass, in which the disadvantages of. bek ^ n ^ th ,, methods are eliminated and a little effort for measurement and evaluation should be associated with meaningful repeatable results for the melting and lautering behavior of glass samples ·

Essence of the invention:

The invention is therefore based on the _object's method for determining the melting behavior of the glass to develop, in which the melting process of the batch until the refined glass over the entire temperature range with respect to the melt-down and Läuterverhaltens for a particular glass composition is investigated on a test series as well as a testing for this method with automated measured value acquisition and evaluation.

According to the invention the object is achieved in that the method for determining the melting behavior of glass is characterized in that the melting of glass over all stages of the entire Sohmelzprozesses from the beginning of silicate formation to the refined glass at a linear temperature increase in certain Zeitinterval-. len via platinum electrodes immersed in the melt, the measured electrical conductivity of the glass batch during the melting process different proportional voltage drops are automatically detected and evaluated.

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According to the invention, two preferably rod-shaped platinum electrodes with a certain distance from one another are arranged centrally in the melting vessel in a melt vessel filled with mixture. "At the end of the melting process, the immersion depth of the electrodes into the glass melt required for error-free measurement is ensured at the end of the melting process

 Purely prone to foaming glasses, the crucible vessel is conical, to ensure that even at and after the maximum of gas evolution and foaming the particular immersion depth of the electrodes is maintained in the melt «, According to the inventive method is a with the platinum electrodes in Keihe switched resistance at linear temperature increase measured the voltage drop, which is proportional to the conductivity of the mixture or »the molten glass · The physico-chemical changes in the glass batch during the Schmmeizprozesses cause different voltage drops, which are a measure of the relative electrical conductivity of the melt»

The Meßwerterfassung- and evaluation takes place at certain intervals preferably by means of a data acquisition system.

The essential advantage of the method according to the invention is that the melting and purging behavior can be determined for different glass compositions, e.g. for a given glass composition, depending on the temperature and time, the individual phases of silicate or glass formation, or e.g. to determine the position of the maximum of the refining and the intensity of the discharge.

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On the basis of the evaluation of the measured value, the condition of the melt is determined at certain temperatures by the following statements being made ζ · Β »

- temperature at the start of melting,

Temperature at the end of silicate formation phases,

Temperature at the beginning and at the end of the glass-forming phases,

Temperature of incipient gas release of the refining phase,

Temperature at maximum gas release during the leaching phase,

Intensity of gas release (from voltage drop in the maximum of gas release),

- Temperature at the completion of the gas birth during the refining phase u «a <>

With comparatively little effort, even for large series, measured values are automatically registered and evaluated, from which statements about time and space can be made quickly. Intensity for smelting and refining of molten glass can be obtained · The investigations are not tied to specific crucible sizes and can be carried out, for example, in harbor smelting «

embodiment

The invention will be explained below in an exemplary embodiment.

FIG. 1 shows the scheme of the test arrangement. FIG. 2 shows the relative electrical conductivity as a function of the melting temperature. The conical melting vessel 2 filled with mixture 1 for 100 g of glass is fed from below into the center of the melting furnace 3 with the aid of a charging device. of a silit stoves. From the top through the oven cover protrudes

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* a measuring probe, the platinum electrodes 4 raittig dip in the batch 1 of the melting vessel 2 and have a distance to the bottom of the melting vessel of about 10 mm · A mounted on the probe thermocouple 5 measures the temperature in the mixture 1 or in the glass bath. By appropriate markings on the adjustable probe holder and charging device ensures that the electrodes 4 are equally deep immersed in the melt »to the platinum electrodes 4 is an AC voltage source. 8 V (50 Hz) preferably connected across a resistor 6 connected in series with the platinum electrodes, the voltage drop is measured, which is proportional to the conductivity of the mixture or the molten glass · The physicochemical connections in the glass pane during the linear heating program melting process, z, B · 5 K / min cause different voltage drops at the resistor 6, which are a measure of the relative electrical conductivity of the melt »To smooth the measured values with simultaneous attenuation of interference frequencies, it is necessary to ground one conductor strand per measuring point» Measured values for the voltage drop and for the temperature in the melting vessel 2 and in the melting furnace 3 take place at certain time intervals, eg "B" 30 s, with the aid of a data acquisition system 7 via a hole punch 8 on perforated strips 9. The electrical conductivities are over time with a digi - grapher or temperature applied · From the curves, the smelting and refining behavior of the melt is assessed. ;

From the curve, the individual phases can be seen during melting of a particular glass. From Figure 2, e.g. to deduce that for the examined glass the area of the silicate formation up to approx. 1399 K

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the phase of the glass formation extends to about 1502 K and the region of the refining to about 1683 K, whereby the maximum of the refining is clearly 1559 K. "

Claims (3)

λ, h - «- 235368 5 Claim w 1. Method for determining the melting behavior of glass, characterized in that measured during the melting of glass over all stages of the entire melting process from the beginning of silicate formation to the refined glass at elevated temperature at certain time intervals via the platinum electrodes plunging into the melt of the electrical conductivity of the batch or molten glass flow proportional, automatically detected and is evaluated. 2. Test arrangement for determining the melting behavior of glass according to item 1, characterized in that two preferably rod-shaped platinum electrodes (4) with a certain distance from each other together with a thermocouple (5) are arranged centrally in a melting vessel (2) and at the end of the melting process a Have the measurement sufficient immersion depth. 3 · Test arrangement according to point 2, characterized in that for particularly prone to foaming glasses, the melting vessel (2) is conical. For this, £ ropes