WO2003002470A1 - Method and device for determining the level of phase boundary surfaces in melted substance containers - Google Patents

Abstract

In order to determine the level of the surface (8) of the melted substance or the level ("H") of a melted glass material (7) in containers (1) having a bottom (2) and an upper bottom surface (3), an ultrasonic transmitter (11) and an ultrasonic receiver (12) are used, in glass melting installations, and the reflection signals from the surface of the melted substance (8) are evaluated. To this end, (a) at least one coupling element (9, 10) is guided through the bottom (2), and the upper side (9a, 10a) of said coupling element is arranged below the surface (8) of the melted glass material (7), at least essentially flush with the upper bottom surface (3); b) at least one ultrasonic element from the group consisting of the ultrasonic emitter (11), ultrasonic receiver (12) and transmitter-receiver unit is arranged on the lower side of the at least one coupling element (9, 10); and c) the level ("H") is determined from the difference in the propagation times of the sound waves between the ultrasonic emitter (11), the ultrasonic receiver (12) or the emitter-receiver unit, deducting the propagation times in the at least one coupling element. The level can be regulated by regulating the supply quantity of filling material, by means of a regulating device (17), in a melted substance vat which is connected upstream from the melted substance container (1), according to the quantity removed from the melted substance container (1).

Description

 Method and device for determining the height of phase interfaces in melt containers

Starting point of the method according to the invention: The invention relates to a method for determining the height of phase interfaces in melt containers with a bottom and an upper bottom surface in glass melting systems using an ultrasound transmitter and an ultrasound receiver and by evaluating reflection signals at these phase interfaces.

Problem:

The glass level measurement and control is - in addition to influencing temperature profiles in the longitudinal direction and in several vertical cross-sectional profiles of a glass channel - an essential prerequisite for fully automatic glass processing for uniform and trouble-free production. Changes in the glass level primarily cause deviating article weights, so that the balance between glass removal and batch inlay is constantly maintained.

State of the art:

Fundamentals of ultrasound technology, the transmitter and receiver, the frequencies, the sound propagation and various applications are described in the "Encyclopedia of Natural Sciences and Technology", 1981, Zwei Burgen Verlag, Weinheim, pages 4718 and 4719. From US-A-4 194 077 and US-A-4 302 623 it is known to determine the layer thickness of feed material (batches, aggregates, cullet) which floats on a glass melt in a melting tank by means of two different measuring methods, namely from above by ultrasonic signals, the reflections of which are detected at the phase boundary between the furnace atmosphere and the feed material, and on the other hand from below by measuring the hydrostatic pressure of the glass melt using a bubbler and a pressure sensor. The layer thickness is then calculated from the difference between the measured values. Since both measurement methods have measurement errors from different causes, there are considerable inaccuracies. In particular, the level measurement by the gas pressure in bubblers, as also described in US Pat. No. 3,200,971, is very imprecise because of the considerable influence of the glass viscosity.

From US-A-4 345 106 it is known to determine the fill level of a glass melt in a melting tank from above by means of ultrasound signals of different frequencies and to infer the position of the melt level by means of phase shift and frequency modulation. Since the ultrasound signals have to penetrate the feed material, which is not homogeneous and causes considerable scattering of the sound waves, this measuring method is also not sufficiently precise.

The problems of "signal noise" due to US reflections on the surfaces of loose beds are discussed by Dr. Berrie and others described in detail in the article "Non-contact level measurements in the glass-making industry", published in International Glass Review, Spring / Summer 1996, pages 75 to 79.

Through the article by Faber and others "Application of Ultrasonic measuring techniques in industrial glass melting", published in Glastech. Ber. 64 (1991), No. 5, pages 117 to 122, it is known to determine the following melting parameters by means of transmitters and receivers immersed in the glass melt from above: a) the presence of bubbles, b) glass flows and c) the corrosion of refractory material , The level measurement is not specified.

Measurements from above, and this also includes the known optical measurements by infrared and laser beams, radioactive radiation and mechanical scanning methods, are always associated with the disadvantage that the superstructure of the melt container (melting tank, working tank and feeder or forehearth) with corresponding Breakthroughs must be provided in which evaporated and again condensed glass components settle. The openings or openings can negatively influence both the melting and the measuring process.

In the book by Fröhler "Glass and Glass Products", information document 50, 1996, published by J. Agst Moers, pages 276/277, various measuring methods for measuring the glass level in feeders are compared with one another, including scanning with a Pt electrode , the electrical resistance measurement, the pneumatic probe and the radioisotopic measurement. The need for openings in the dining area and purging air is also pointed out there.

Similar limiting comments are also in the glass tech. Ber. Glass Be. Techno !. 73 C2 (2000), pages 111 to 123, in the chapter "Sensors for Glass Melting Processes" by Faber et al. to find. It concludes on page 119 that the use of acoustic sensors is still limited because the interpretation of the acoustic reflections from glass melts is rather complex, and that such ultrasound measurements only provide local information about the glass melt (defects, speed) or about the refractory material Deliver (wall thickness).

The "HVG Communication No. 1801" by Fleischmann et al. From August 1, 1993 and the "HVG Communication No. 1875" on a lecture by Fleischmann on June 5, 1996 deal with lateral ultrasonic measurement methods for determining the residual wall thickness of glass channels on the occasion of the 70th DGG Glass Technology Conference in Cottbus. However, it is not about the level measurement.

From DE 198 47 318 C1 it is also known to introduce heating electrodes through the bottom of glass melting tanks, which are provided at their lower ends with transmitters and receivers for ultrasonic signals. However, this should determine the remaining length of the electrodes, which is decisive for the heating power. By heating the electrodes depending on the signal, the heating output should be adjusted to constant values. However, this is also not a level measurement.

Object of the invention:

In contrast, the invention is based on the object of specifying a method of the type described at the outset with which it is possible to determine the fill level or the height of the melt level above the upper bottom surface of a melt container exclusively by means of ultrasonic signals and their metrological processing, without having to do so in the superstructure the melt container recesses and / or openings would have to be provided.

Solution by the process part of the invention:

The object is achieved in the method specified at the outset according to the invention by determining the fill level of a glass melt in the melt container by a) passing at least one coupling element through the bottom thereof and at least essentially flushing the top thereof below the melt level of the glass melt arranges the upper floor surface, b) arranges at least one ultrasound element from the group of ultrasound transmitter, ultrasound receiver and transmitter-receiver unit on the underside of the at least one coupling element, and c) from the transit time difference of the sound waves between the ultrasound transmitter, ultrasound receiver or transmitter-receiver unit below Deduction of the transit times in the at least one coupling element determines the fill level. Advantages of the invention:

The object of the invention is achieved in full, namely to determine the fill level or the height of the melt level above the upper bottom surface of a melt container exclusively by means of ultrasound signals and their measurement processing, without recesses and / or openings being provided in the superstructure of the melt container would.

In addition, the following further advantages are associated with this: It is a simple mechanical structure for direct measurement of the fill level, so that a corresponding device can also be used to replace other devices and to retrofit existing melt containers, one or more times at almost any place on the bottom of the melting tank, working tank and feeder or forehearth. Depending on the measuring principle, only one or two openings in the base are required in order to bring the coupling element or the coupling elements into contact with the glass melt. Moving parts are no longer necessary, as are dangerous radiation sources that require approval, such as radioactive substances. The measurement accuracy is amazingly high. For example, level differences of only 0.1 to 0.3 mm can be corrected. Known systems such as piezo crystals can be used as transmitters and receivers.

The avoidance of breakthroughs in the superstructure or in the furnace ceiling avoids the impairment of the glass melt and the temperature and viscosity distribution in the glass melt by undesired gas leaks and / or air ingress and thus process disturbances. Furthermore, condensation of vaporized glass components and accumulations of solids on the measuring devices are avoided. Finally, undesired interactions with necessarily existing heating or cooling devices in the upper furnace and / or in the ceiling of the melt container are also avoided. Further refinements of the method according to the invention: In the course of further refinements of the method according to the invention, it is particularly advantageous if, either individually or in combination:

* Separately, in the bottom of the melt container, arranges two coupling elements perpendicularly and parallel to one another and provides one coupling element on its underside with an ultrasound transmitter and the other coupling element on its underside with an ultrasound receiver,

arranges a vertical coupling element in the bottom of the melt container, which is provided on its underside with a transmitter-receiver unit for ultrasonic signals,

* the ultrasound transmitter is charged with a pulse train for the generation of ultrasound signals via a data processing device and the portions of the ultrasound signals reflected at the phase interfaces are analyzed by means of the data processing device and signals for the fill level are obtained therefrom, and / or if one

* the actual value signals for the fill level as well as setpoint signals for the fill level of a control arrangement are activated and the control arrangement regulates the balance between the supply and removal quantities of glass melt in and out of the melt container to predetermined values, especially if the control quantity regulates the supply quantity of Charging material in a melting tank upstream of the melt container controls according to the amount withdrawn from the melt container.

Further advantageous refinements of the method according to the invention result from the remaining method claims. Starting point of the device according to the invention: The invention also relates to a device for determining the height of phase interfaces in melt containers with a bottom and an upper bottom surface in glass melting systems using an ultrasound transmitter and an ultrasound receiver and by evaluating reflection signals at these phase interfaces.

Solution by the device part of the invention:

To achieve the same object, such a device according to the invention is characterized in that, in order to determine the fill level of a glass melt in the melt container a), at least one coupling element is passed through the bottom thereof, the upper side of which is arranged at least substantially flush in the upper bottom surface below the melt level of the glass melt is b) at least one ultrasound element from the group of ultrasound transmitter, ultrasound receiver and transmitter-receiver unit is arranged on the underside of the at least one coupling element, and if c) a data processing device is provided by which the transit time difference of the sound waves between ultrasound transmitter, ultrasound receiver or Transmitter-receiver unit with deduction of the transit times in which the fill level can be determined in the at least one coupling element.

Further refinements of the device according to the invention: In the course of further refinements of the device according to the invention, it is particularly advantageous if - either individually or in combination:

* Separate, perpendicular and parallel to each other, two coupling elements are arranged in the bottom of the melt container, one coupling element on the underside of which is provided with an ultrasound transmitter and the other coupling element on the underside of which is provided with an ultrasound receiver, a vertical coupling element is arranged in the bottom of the melt container and is provided on its underside with a transmitter-receiver unit for ultrasonic signals,

* the ultrasound transmitter can be loaded with a pulse sequence for the generation of ultrasound signals via the data processing device and if the portions of the ultrasound signals reflected at the phase interfaces can be analyzed by means of the data processing device and signals for the fill level can be obtained therefrom,

* the actual value signals for the fill level as well as setpoint signals for the fill level of a control arrangement are switched on and by means of the control arrangement the equilibrium between the supply and the withdrawal quantities of glass melt in and out of the melt container can be adjusted to predetermined values,

* the coupling elements consist of at least one material from the group of ceramic materials, refractory materials with low thermal conductivity, metals and composite materials, and / or if

* The coupling elements are provided with a cooling device.

EXAMPLES

Exemplary embodiments of the subject matter of the invention and their mode of operation are explained in more detail below with reference to FIGS. 1 to 4.

Show it:

FIG. 1 shows a highly abstracted vertical section through a first exemplary embodiment, in which ultrasonic transmitters and receivers are arranged separately from one another, FIG. 2 shows a vertical section through a second exemplary embodiment analogous to FIG. 1, but in which ultrasonic transmitters and receivers are structurally combined,

FIG. 3 shows the envelope curves of oscillator diagrams of the receiver with two different surface states of the glass melt (top and bottom) and the formation of differences from these diagrams (middle), and

Figure 4 shows a detail of Figure 1 on an enlarged scale, modified in such a way that an insulating material is arranged between the coupling element and the bottom of the melt container.

FIG. 1 shows a cross section through a melt container 1, which in the present case is a feeder channel or a forehearth. This has a floor 2 with an upper, horizontal and flat floor surface 3 and two side walls 4 and 5 and a ceiling 6. These components consist of refractory materials. Thermal insulation, outer jacket, frame parts and heating and cooling devices are omitted for the sake of simplicity. The melt container 1 is filled with a glass melt 7, which reaches up to a melt level 8, the height of which is an amount "H" above the bottom surface 3, which characterizes the fill level.

Two coupling elements 9 and 10 are passed through the bottom 2 in the vertical direction, the flat upper sides 9a and 10a of which lie in one plane with the bottom surface 3 and are touched by the glass melt 7. The coupling elements 9 and 10 carry at their lower ends an ultrasonic transmitter 11 and an ultrasonic receiver 12, hereinafter referred to as "transmitter" and "receiver" for short.

Transmitter 11 and receiver 12 are connected via lines 13 and 14 of a data processing device 15, which - not particularly shown - a control unit, a signal processor and a microcomputer contains. The control unit controls the delivery of the pulses to the transmitter 11. The receiver 12 passes the received pulse train to the data processing device 15. Its output signals are applied via a line 16 to a control arrangement 17 for the fill level. Inputs and outputs for setpoints and control signals are not shown. For example, the charging device of a melting tank can be controlled or regulated by the control arrangement 17 in order to maintain the balance between the supply of glass raw materials and the removal of glass melt. The data processing device 15 generally includes an input keyboard 15a, a display device 15b and a printer 15c for signal recording. The input keyboard can be dispensed with if programmed accordingly.

Since the glass melt 7 can have temperatures of 900 ° C to approximately 1,600 ° C depending on the type of glass and the transmitter and receiver, for which piezo crystals can only withstand temperatures of less than 350 ° C, the coupling elements 9 and 10 consist of one ceramic material or a refractory material with low thermal conductivity, a metal or composite material and have a corresponding length. Possibly. they can also be provided with cooling devices, not shown.

The coupling element 9 emits ultrasound waves via its upper side 9a, part of which is reflected at the melt mirror 8 towards the upper side 10a of the coupling element 10, which is indicated by the arrows 18. Each coupling element is in direct contact with the glass melt on the one hand and the transmitter and receiver on the other.

The data processing device 15 emits a sequence of ultrasonic pulses via the transmitter 11, which runs through the coupling element 9 of the transmitter 11 and through the glass melt 7 to the melting mirror 8 and from there back to the coupling element 10 and to the receiver 12 (arrows 18). At the material or phase interfaces passed through, transmitter / coupling element, coupling element / glass melt, glass melt / furnace atmosphere (melt level) and back, glass melt / coupling tion element, coupling element / receiver, reflections occur, which are registered as temporally staggered pulse sequences by the receiver. The data processing device 15 extracts the transit time signal for the melt surface (the melt level 8) and thus the entire pulse transit time from this pulse sequence. The total impulse running time t _imp is made up of the running times of the individual sections:

(1) = _ki + 2 xt _glass + t _k2> where t _k1 = pulse _{transit time} in the coupling _{element of} the transmitter, t _k2 = pulse _{transit time} in the coupling _{element of} the receiver and t _G i _as ⁼ pulse transit time in the glass melt.

The determination of the fill level of the glass melt by the data processing device 15 can be determined by various methods, the data processing device 15 carrying out the selection of the pulse sequences and hiding the reflections on the coupling elements and determining the total pulse transit time t _imp .

The following procedures have been successfully tested:

a) The speeds of sound for all materials are known:

If the speeds of sound and the lengths of the coupling elements and thus the pulse duration are known, the pulse duration in the glass melt can be calculated on the basis of the total pulse duration and the path length in the glass melt can be determined if the speed of sound in the glass melt is known:

(2) t _G , _as = 0.5 x (t _imp - t _k1 - t _k2 ), where

^ Glass ⁼ glass ^x tgias ^and d

S _Gias = path length in the glass melt and ^v _G ia _s = speed of sound in the glass melt. b) The speeds of sound are only known for the coupling elements:

If the speeds of sound and the lengths of the coupling elements are known, the pulse duration in the glass melt can be calculated based on the total pulse duration:

(3) t glass 0.5 X (t _imp - t _k1 - t _k2 )

Using a parameterization cycle by defined raising and lowering the fill level of the glass melt, the change in the pulse transit time Δt _imp can be measured and from this the change in the pulse transit time in the glass melt Δt _{G) as} can be determined and the speed of sound - v _G | _as - be calculated. The device can be used in the glass melt - v _G | _as - be parameterized:

(4) v _glass = ΔS _{G (as} / Δt _glass .

c) The sound velocities in the materials are not known: the change in the pulse transit time Δt _imp can be measured using a parameterization cycle by defined raising and lowering the fill level of the glass melt. Since the lengths of the coupling elements are constant, their pulse transit times are also constant. This means that the change in the pulse transit time is due to the change in the pulse transit time in the glass melt:

(5) Δt _imp = Δt _G , _as .

The speed of sound - v _{G | as} - is calculated with a known pulse transit time in the glass melt Δt _glass . The device can be parameterized by means of the now known speed of sound in the glass melt - v _G ι _as . The data processing device 15 selects the pulse transit time in the glass melt t _G | _as from the entire pulse train. If the pulse duration in the glass melt is known, the fill level "H" of the glass melt can be calculated if the sound velocity ^v _G i _{as is} known, or if the speed is unknown

Speed of sound can be determined by a parameterization cycle, as described above.

In Figure 2, the same reference numerals are used for the same parts or parts with the same function. In this case, the transmitter and receiver are connected to a transmitter-receiver unit 19 with a likewise vertically arranged coupling element 21, which also has a flat and horizontal upper side 21 a, which lies flush in the upper floor surface 3. Ultrasonic waves are now emitted from this upper side 21a and return to it, which is indicated by the vertical parallel arrows 20.

FIG. 3 shows the envelopes S1 and S2 of the oscillator diagrams of the receiver in the case of two different surface states and the formation of differences from these diagrams (envelopes S3). To a certain extent, these envelopes outline the amplitudes of the vibrations. These are the envelopes of ultrasonic pulses that were recorded with an oscillograph after appropriate amplification.

The receiver signal resulted from longitudinal, transverse and surface waves. The time of arrival of the signals from the melt level 8 can be clearly recognized and evaluated from the transit time interval corresponding to H '. Similar evaluations can be obtained from a phase comparison of the pulse sequences. The data processing device is programmed using appropriate software, taking into account the above calculation bases. The display and measurement accuracy was between about 0.1 and 0.3 mm mirror difference.

Figure 4 shows a section of the left half of Figure 1 on an enlarged scale, modified in such a way that between the built Circumferential surface 9b of the coupling element 9 and the perforated wall 2a of the bottom 2 of the melt container 1, an insulating material 22 is arranged, which attenuates or eliminates the transverse waves and reflections from the bottom 2 to the coupling element 9. The insulating material 22 has the shape of a sleeve and consists of a heat-resistant material with a lower density than the floor material. To the glass melt 7, the insulating material 22 is protected by a protective layer 23 made of a material resistant to the glass melt, for example from the thinnest possible ring made of platinum. The top of this protective layer 23 lies in the same plane as the bottom surface 3 and the top 9a of the coupling element 9. This installation measure is expediently also used for the coupling elements 10 and 21.

LIST OF REFERENCE NUMBERS

1 melt container

2 floor

2a perforated wall

3 floor space

4 side wall

5 side wall

6 blanket

7 melted glass

8 melt level

9 coupling element

9a top

9b peripheral surface

10 coupling element

10a top

11 ultrasound transmitters

12 ultrasound receivers

13 line

14 line

15 data processing device

15a input keyboard 15b display device

15c printer

16 line

17 Control arrangement

18 arrows

19 Transmitter-receiver unit

20 arrows

21 coupling element

21a top

22 insulation

23 protective layer

"H" measure of level

S1 envelopes

S2 envelopes

S3 envelopes

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Claims

Patent claims: Method for determining the height of phase interfaces in melt containers (1) with a bottom (2) and an upper bottom surface (3) in glass melting systems using an ultrasonic transmitter (11) and an ultrasonic receiver (12) and by evaluating reflection signals on these phases -Interfaces, characterized in that the fill level ("H") of a glass melt (7) in the melt container (1) is determined by a) passing at least one coupling element (9, 10, 21) through its bottom (2). and the top side (9a, 10a, 21a) of which is arranged below the melt level (8) of the glass melt (7) at least essentially flush in the upper bottom surface (3), b) on the underside of the at least one coupling element (9, 10, 21) at least one ultrasonic element from the group of ultrasonic transmitters (11), ultrasonic receivers (12) and transmitter-receiver unit (19), and c) from the transit time difference of the sound waves between the ultrasonic transmitter (11), ultrasonic receiver (12) or transmitter-receiver unit (19) determines the fill level (“H”), deducting the transit times in the at least one coupling element (9, 10, 21). Method according to claim 1, characterized in that in the ground (2) of the melt container (1) arranges two coupling elements (9, 10) separately, perpendicularly and parallel to one another and one coupling element (9) on its underside with an ultrasonic transmitter (11) and the other coupling element (10) on its underside an ultrasound receiver (12). 3. The method according to claim 1, characterized in that a vertical coupling element (21) is arranged in the bottom (2) of the melt container (1), which is provided on its underside with a transmitter-receiver unit (19) for ultrasonic signals. 4. The method according to claim 1, characterized in that the ultrasound transmitter (11) is subjected to a pulse sequence for the generation of ultrasound signals via a data processing device (15) and the portions of the ultrasound signals reflected at the phase boundaries are analyzed by means of the data processing device (15). and uses this to obtain signals for the fill level (“H”). 5. The method according to claim 4, characterized in that the actual value signals for the fill level ("H") and the setpoint signals for the fill level ("H") are connected to a control arrangement (17) and the balance is achieved by means of the control arrangement (17). between the supply and removal quantities of glass melt in and out of the melt container (1) is adjusted to predetermined values. 6. The method according to claim 5, characterized in that the supply quantity of charging material into a melting tank upstream of the melt container (1) is regulated by means of the control arrangement (17) in accordance with the quantity removed from the melt container (1). 7. The method according to claim 1, characterized in that the material for the coupling elements (9, 10, 21) and their length are selected in such a way that the temperature depends on the temperature of the glass melt on the top (9a, 10a, 21a). the coupling elements (9, 10, 21) at the lower ends of the coupling elements (9, 10, 21) are lowered to a temperature which corresponds at most to the maximum permissible operating temperature of the ultrasonic elements (11, 12, 19). 8. The method according to claim 7, characterized in that the coupling elements (9, 10, 21) are cooled. 9. The method according to claim 4, characterized in that a) the data processing device (15) is designed in such a way that it emits a sequence of ultrasonic pulses via the transmitter (11) or the transmitter-receiver unit (19). the respective coupling element (9, 21) and through the glass melt (7) to the melt level (8) and from there back to the coupling element (10, 21) and to the receiver (12) or to the transmitter-receiver unit (19), b) the reflections occurring at the material or phase boundary surfaces of the transmitter/coupling element, coupling element/glass melt, glass melt/furnace atmosphere (melt mirror) and back through the glass melt/coupling element, coupling element/receiver are registered as time-offset pulse sequences by the receiver, c) the data processing device (15) The transit time signal for the melt level (8) and thus the entire pulse transit time is extracted from the pulse sequence, whereby the total pulse transit time t _imp is composed of the transit times of the individual sections as follows: tim _p = t _k1 + 2 xt _glass + t _k2 , where t _k1 = pulse transit time in the transmitter's coupling element, t _k2 = pulse transit time in the receiver's coupling element and _that = pulse transit time in the glass melt. 10. The method according to claim 1, characterized in that with known sound speeds and pulse transit times for all materials and with known lengths of the coupling elements (9, 10, 21), the pulse transit time and the path length (s) in the glass melt are determined based on the total pulse transit time as follows become: t _G ias = 0.5 x (t _imp - t _k1 - t _k2 ), where ^S glass = ^v glass ^x tQlas ^and S _G!as = path length in the glass melt and ^v Gias ⁼ speed of sound in the glass melt. 11. The method according to claim 1, characterized in that with known sound speeds and lengths, the pulse transit time in the glass melt is calculated only for the coupling elements based on the total pulse transit time: tdas ^{= u} .5 X (tj _mp - t _k1 - t _k2 ), where using a parameterization cycle by defined raising and lowering of the fill level of the glass melt, the change in the pulse transit time Δt _imp is measured and from this the Change in the pulse transit time in the glass melt Δt _G | _as determined and the speed of sound - v _G | _as - is calculated and where the Device is parameterized using the now known speed of sound in the glass melt - V _Q ^ - as follows: ^v G _l as ⁼ ΔS _G | _as / Δt _G | _as . 12. The method according to claim 1, characterized in that with unknown speeds of sound in the materials and constant lengths and pulse transit times of the coupling elements (9, 10, 21), the change in the pulse transit time Δt _irnp is measured using a parameterization cycle by defined raising and lowering of the fill level of the glass melt will, whereby the Change in the pulse transit time can be attributed to the change in the pulse transit time in the glass melt as follows: jmp = Δt _G)as , and with the known pulse transit time in the glass melt Δt _G!as the speed of sound - v _G ι _as -in the glass melt is calculated and the device using the now known speed of sound ity in glass melting - v _G | _as - is parameterized. 13. Device for determining the height of phase interfaces in melt containers (1) with a bottom (2) and an upper bottom surface (3) in glass melting systems using an ultrasonic transmitter (11) and an ultrasonic receiver (12) and by evaluating reflection signals these phase interfaces, characterized in that for determining the fill level ("H") of a glass melt (7) in the melt container (1) a) through its base (2) at least one coupling element (9, 10, 21), the top (9a, 10a, 21a) of which is arranged at least essentially flush in the upper bottom surface (3) below the melt level (8) of the glass melt (7), b) on the underside of the at least one coupling element (9, 10, 21) at least one ultrasonic element from the group of ultrasonic transmitters (11), ultrasonic receivers (12) and transmitter-receiver unit (19) is arranged, and that c) a data processing device (15) is provided which the fill level ("H") can be determined from the transit time difference of the sound waves between the ultrasonic transmitter (11), ultrasonic receiver (12) or transmitter-receiver unit (19), deducting the transit times in the at least one coupling element (9, 10, 21). . 14. The device according to claim 13, characterized in that in the bottom (2) of the melt container (1) two coupling elements (9, 10) are arranged separately from one another, perpendicular and parallel to one another, one of which has a coupling element (9) on its underside an ultrasound transmitter (11) and the other coupling element (10) is provided on its underside with an ultrasound receiver (12). 15. The device according to claim 13, characterized in that a vertical coupling element (21) is arranged in the bottom (2) of the melt container (1), which is provided on its underside with a transmitter-receiver unit (19) for ultrasonic signals. 16. Device according to claim 13, characterized in that the Ultrasonic transmitter (11) can be acted upon via the data processing device (15) with a pulse sequence for the generation of ultrasonic signals and that the portions of the ultrasonic signals reflected at the phase interfaces can be analyzed by means of the data processing device (15) and signals for the fill level ("H") are derived from them. are winnable. 17. The device according to claim 16, characterized in that the actual value signals for the fill level and the setpoint signals for the fill level ("H") of a control arrangement (17) are switched to and the balance between the supply and Removal quantities of glass melt in and from the melt container (1) can be adjusted to predetermined values. 18. The device according to claim 13, characterized in that the coupling elements (9, 10, 21) consist of at least one material from the group of ceramic materials, refractory materials with low thermal conductivity, metals and composite materials. 19. The device according to claim 18, characterized in that the coupling elements (9, 10, 21) are provided with a cooling device. 20. The device according to claim 13, characterized in that an insulating material (22) for the suppression of transverse vibrations and reflections of the ultrasonic signals is arranged between the coupling elements (9, 10, 21) and the bottom (2) of the melt container (1). . 21. The device according to claim 20, characterized in that the insulating material (22) is heat-resistant, has the shape of a sleeve and consists of a material with a lower density than the base material. 22. The device according to claim 20, characterized in that the insulating material (22) is covered with respect to the glass melt (7) by a protective layer (23) made of a material that is resistant to the glass melt (7).