DE10304973A1 - Control unit for melting and/or refining glass has control devices which form at least two regulating circuits - Google Patents

Abstract

The invention relates to a control device (1) for a system (2) for melting and / or refining glass, which is characterized in that the control device has control devices (50, 60) which form at least two control circuit levels. In addition, a method for regulating a system for melting and / or refining glass is provided, which comprises the following method steps: detecting at least one controlled variable, detecting at least one process variable corresponding to the controlled variable, determining at least one manipulated variable for controlling the process variable, and which characterized in that at least one manipulated variable is determined in a control system which comprises at least two control loop levels, the respective higher-level control loop level specifying the desired values for the respective lower control loop level.

Description

The invention relates to a control device and a method for regulating a plant for melting and / or Purify of glass according to the characteristics of claims 1 and 25.

Purification means the removal of bubbles and dissolved gases from glass melts, which is carried out continuously in devices such as that in the application DE 199 39 779 A1 the system described by the applicant can be carried out.

Usually will be the purification performed by melting glass by adding substances that with a temperature increase Release gases that diffuse into existing bubbles and enlarge them. Thereby can the bubbles rise out of the melt faster and out of it escape.

In continuously operated plants, the purification can be carried out by applying reduced pressure. This method and its embodiments are described, for example, in the following documents:
In EP 0 989 099 A1 . EP 0 967 180 B1 . EP 0 231 518 B1 and JP 11255519 A methods and devices for vacuum purification are generally described. US 1,598,308 describes a refining unit with a riser tube, horizontal refining chamber and downpipe. In JP 09156932 A . JP 02188430 A and EP 1 044 929 A1 describes the degassing by storing the glass melt under reduced pressure for a certain time. The documents EP 0 253 188 A1 . US 4,919,700 . JP 07291633 A and US 4,704,153 aim in particular to remove foam. For this purpose, the addition of substances such as water that break the foam, a suitable design of the cross-section through which the glass flows, or the heating of the head space of the vacuum chamber is used.

To remove foam, refining gas can also be generated by refining agents in the glass melt, for example in accordance with the applicant's application DE 199 39 771 A1 ,

For refining, the high-frequency refining method developed by the applicant can also be used without the use of toxic refining agents such as As ₂ O ₃ or Sb ₂ O ₃ . This process is based on the fact that the melt is led through an alternating electrical field of a coil, the field being coupled directly into the glass. The unit walls are designed as skulls, with the glass melt reaching a temperature of more than 1900 ° C. The high frequency ringing process is described in detail in the following patents:
DE 199 39 773 A1 and DE 199 39 786 A1 relate to devices and methods, wherein in glass, which is located in cooled refining vessels, high-frequency energy is inductively coupled into the glass melt in the refining vessel from a high-frequency device.

The high-temperature lautering process developed by the applicant can also be used for refining. In the registration DE 102 56 657.7 describes a heating device and a melting unit which, due to improved cooling, enable efficient heating of the melt. In DE 102 56 594.5 describes a method and a device for heating melts so that the walls of the melting unit can be cooled sufficiently and at the same time more energy is supplied to the melt than is withdrawn through the cooled walls. The content of the two registrations DE 102 56 657.7 and DE 102 56 594.5 is hereby incorporated by reference into the present application.

Due to the reactions occurring during the melting process, a glass melt contains gases in chemically and / or physically dissolved form as well as in the form of bubbles. The aim of every refining process is to remove as much as possible the bubbles contained in the glass melt and at least some of the dissolved gases. These gases include, for example, H ₂ O, CO ₂ , SO ₂ , N ₂ , O ₂ and Ar.

To carry out the refining process in a regulated manner can, it is necessary to know the physical-chemical relationships. In order to be able to set up a regulation, it is necessary, these relationships to describe in a model measure the necessary material and process parameters as well as strategies and algorithms for the regulation of the refining process to develop.

To develop a solution for this task, be first considered the bubbles introduced into the melt. Right away After the melting process, the bubbles are in the melt a specific location dependent Volume density, size distribution and composition. Approximately can at this point it can be assumed that the composition the bubbles essentially coincide with those in the surrounding glass melt and deviates little from their surroundings. By in the melting unit Existing convection will move the bubbles to other locations with others Temperatures transported. The bubbles have due to their The effort to counteract the acceleration of gravity or other additional imprinted Accelerations to ascend.

In general, the following measures can be used to reduce the number of bubbles in the melt: reducing the number of start bubbles immediately when melting, shortening the bubble ascent paths by bringing the bubbles close to the surface of the glass bath, increasing the bubble ascent rate in the glass melt, resorption of the remaining bubbles from the melt as well as lowering the gas content of the melt.

If the raw materials, their composition and the possibilities for their preparation and the refining agent are not changed can, can by the temperature control of the process on the starting bubbles and thus the number the starting bubbles are reduced immediately when melting.

To shorten the path of the bubble ascent by introducing them the bubble close to the glass bath surface is suitable, for example an area in a melting unit where the glass bath depth is strong is reduced. Also by skillful adjustment of the convection areas containing bubbles can be very close and very common the glass bath surface transport.

With regard to increasing the bubble ascent rate in the glass melt, the bubble ascent rate is considered: the bubble ascent rate v is given according to Stokes law by:

Ρ denote the density and η the viscosity of the glass melt, g the gravitational acceleration and r the bubble radius.

One can see that an increase in Acceleration g, for example by centrifugation, and by a decrease in viscosity η, for example by an increase in temperature, as well as particularly strong by increasing the bubble radius r die Bubble ascent rate v can be increased. Because of the square dependence the bubble ascent rate from the bubble radius is preferred the latter sought. Significant bladder enlargement can preferably be achieved by Diffusion of gases from the melt into the bubbles are caused.

gegeben durch

mit folgenden Zusatzgleichungen

The temporal change in the bubble radius r is in the case of a temporally stationary temperature field

given by

with the following additional equations

Designate:
R: gas constant
T: temperature D _i : diffusion constant
L _i : solubility
Sh: Sherwood number
p _{i, G} : pressure of the i-th gas species in the glass melt
p _{i, B} : pressure of the i-th gas species in the bladder
p _A : atmospheric pressure
ρ: density of the glass melt
g: gravitational acceleration
z: depth of the bubble
σ: surface tension
- the speed of the bladder given in the fixed reference system

• 1. der in die Blase eindiffundierten Stoffmenge
  
  aufgrund der Partialdruckdifferenz p_i,G – P_i,B,
• 2. der Änderung des Atmosphärendrucks
  
• 3. der Änderung des hydrostatischen Drucks
  
  und
• 4. der Bewegung der Blase in einem räumlich inhomogenen Temperaturfeld
  

The change in the bubble radius r over time is made up of the following terms, which characterize the respective driving force:

• 1. the amount of substance diffused into the bladder
  
  due to the partial pressure difference p _{i, G} - P _{i, B} ,
• 2. the change in atmospheric pressure
  
• 3. the change in hydrostatic pressure
  
  and
• 4. the movement of the bubble in a spatially inhomogeneous temperature field
  

The blister enlargement in conventional refining processes usually takes place in that a substance added to the melt in an adapted concentration (for example As ₂ O ₅ , SnO ₄ , HCl) releases a gas from a certain temperature. This gas diffuses into existing bubbles or leads to the formation of new bubbles if the gas pressure is so high that it cannot be broken down sufficiently quickly by diffusion. By varying the chemical composition of the added substance, its concentration, the glass composition and the temperature and flow field in the production unit, the degree of bubble enlargement and the associated bubble removal can be adjusted. This requires knowledge of the concentration of the bubbles initially present, their composition, their volume density, size distribution and starting locations. In addition, the concentration or the partial pressure of the gases dissolved in the melt must be known.

The resorption of the remaining bubbles is decisive for the removal of the bubbles which have not escaped from the melt and whose contents consist of gases which have a substantially lower partial pressure when the temperature of the melt is reduced. In addition, the absorption of gases in a bubble can be improved by increasing the atmospheric gas pressure. This process is supported by the surface tension σ of the glass melt (typically 0.3 N / m) when the bubbles have become sufficiently small. The surface tension leads to a pressure p _Os , which is given by

With very small bubbles, that means r <20 μm, p _{os can become} very large.

Dissolved gases can exceed the boiling line, which either at constant pressure by increasing the temperature or at constant temperature can be done by lowering the pressure, fail uncontrolled in the form of bubbles (reboil). Furthermore, it by interacting with the surfaces of the refractory to separate bubbles. To reduce the extent of this undesirable In addition to removing the bubbles, processes also involve lowering the gas content of a melt.

The lowering of the gas content continues a noteworthy mass transfer of gas to the glass bath surface ahead. in principle the gas content of a melt can be reduced by using a preferably size Partial pressure difference for the gases to be removed is built up, and on the other hand the mass transfer facilitated by a high temperature and the largest possible mass transfer area becomes. Finally should if possible a lot of gas on the surface of the gas bath transported where it can easily escape. With the conventional lautering however, only a small amount of gas dissolved in the melt away.

Suitable measures for increasing the partial pressure difference for the gases dissolved in the melt are, for example, passing a purge gas of a different type through the glass melt or lowering it of the ambient pressure. It is advantageous for the vacuum purification that all gases are removed without a purge gas remaining in the melt. When using a purge gas, process problems such as reboil cannot be completely ruled out, as part of the purge gas can dissolve in the melt.

The gases in the glass melt are transported over short distances by diffusion, which is very slow: typical diffusion coefficients for gases in glass melts are around 10 ⁻¹ m ² s ⁻¹ . In addition to the glass bath surface, the largest possible internal gas exchange surface must be created. Bubbles with a sufficiently large volume density are suitable for this, which already have a high specific surface area. These bubbles are either actively passed through the melt (eg through fine bubbling) or are created as a result of negative pressure due to heterogeneous nucleation. In addition to their rate of buoyancy, the gas transport by bubbles can also be supported by convection of these bubbles to the glass bath surface.

So that the bubbles can be removed stably and trouble-free while simultaneously reducing the residual gas content, the necessary processes must take place in a certain way between the entry and exit of the glass in a refining unit. In order to be able to control these processes in a targeted manner, reliable control is therefore necessary. One possibility for the regulation of processes for the production of glass is, for example, in the patents FR 2 781 786 . DE 97 66 85 T1 "Device for controlling the melting and / or degassing of glass melting furnaces" described.

A controlled system is established in accordance with DIN 19226 (cf. 1 ) composed of the following components: in a controller there is a control difference between a reference variable and a controlled variable. The controlled variable is influenced by disturbance variables. The controller output variable acts as a manipulated variable on an actuator, which influences the controlled variable. In the literature, the reference variable is often referred to as the setpoint and the controlled variable as the actual value. It is known in principle how the refining of glass has to be carried out. As described, this includes the elimination of bubbles and a significant reduction in the gases dissolved in the melt. However, experience has shown that this process cannot be carried out stably to the desired extent. In addition, the number of bubbles in the product cannot easily be safely kept below a certain limit. The complexity of the procedure therefore requires a control concept based on a large number of input and output variables (multiple input multiple output control: MIMO control).

It was found that the stability and continuous operability of devices and methods for refining by installing a regulation can be significantly improved. It also has shown that the scheme in the manner described above is very is helpful to prevent accidents and other dangerous or for the product quality harmful Influencing factors (e.g. freezing of the glass in the system, excessive corrosion, New blister formation in the refining area - i.e. in the Bubble growth area, excessive foaming) to minimize.

From the circumstances described above is therefore the object of the invention, a control device for a system for melting and / or refining of glass available to deliver.

This task is already being solved in a simple manner by a device with the features of the claim 1. Furthermore, a method is specified in claim 25, with which Regulation can be carried out using the device. advantageous Further training can be found in the assigned subclaims.

The control device for a system for melting and / or refining von Glas has two control devices, which are at least two Form control loop levels. At least one manipulated variable is determined in this control system, by at least one control variable as well at least one corresponding to this controlled variable Process size recorded becomes. The set of rules according to the invention is made up of a hierarchically structured controller structure together.

The controller of the highest level is responsible for the quality function the bubble density and the residual gas content. Low level regulator serve the self-sufficient control of the individual process parameters: for example the foam height in the refining unit with means of top heat and the injection of substances for acceleration of foam decay can be regulated. A constant glass bath depth in the refining unit can take into account, for example, by setting the residual pressure throughput and temperature are regulated.

The control device according to the invention also has a linking device which can link a large number of setpoints and / or actual values to one another via a plurality of control loop levels. In particular, the linking device works according to a so-called multiple input multiple output system (MIMO system). By linking the large number of setpoints and / or actual values across several control loop levels, the invention enables a separation of different process steps, although the overriding process target can still be controlled with a single control: if, for example, a greater reduction in the residual gas content would be desired, one would wish preferably separate the process steps "lowering the gas content" and "bubble removal". This process of gas removal must take place before bubble removal and, because it is associated with bubble generation, be careful be coordinated with the bubble removal process. Such coordination of different process steps with one another is advantageously possible with the invention. In addition to the model-based control strategies of the MIMO method, the control loop linkage can also include at least one of the following strategies: PID, fuzzy, neural networks and adaptive controls.

Depending on the task of the controller, lower Level can already adjusted target values can be determined from input data. As setpoints can not only measured values, but also derived values are used become. These advantages are realized in that the control loop levels are arranged hierarchically, the at least one control device the parent Control loop level comprises a first default device with which the at least one control device of the respective subordinate Control loop level setpoints can be specified.

The at least one control device the parent Loop level also includes one second default device with which direct manipulated variables are predefined can be. Because this way, control values are determined directly at a high level in addition to setpoints can be allows the invention (if necessary) to save a control level. So can the manipulated variable directly The complexity of the rules can be determined from input data be significantly reduced. The further rationalization of the device serves the possibility according to the invention that a specification device the first specification device for specifying the setpoints and the second specification device for specifying the Includes manipulated variables.

• – Temperatur
• – atmosphärischer Restdruck in der Läuterkammer
• – Heizleistung
• – Heizleistung in vor- und/oder nachgeschalteten Prozessschritten
• – Gemengefeuchte
• – Gemengelage
• – Gemengeform
• – Volumenstrom durch die Glasdüsen
• – Glasstand in der Schmelzwanne und/oder in der Läuterwanne und/oder in der Rinne und/oder im Rührtiegel
• – Viskosität des Glases
• – Durchsatz des Glases
• – Sauerstoffpartialdruck des Glases
• – Wassergehalt des Glases
• – Sauerstoffpartialdruck des Abgases
• – Ofendruck in der Schmelzwanne
• – Schaumhöhe
• – Form des Schaums
• – Lage des Schaums
• – Druck und/oder Volumenstrom des Schutzgases
• – Blasenbildungsrate in der Schmelzwanne
• – Rührerdrehzahl
• – Sauerstoffpartialdruck an Edelmetallbauteilen.

Because the relationship between the glass quality and the controlled variables and a wide variety of influencing parameters can be mastered with the control according to the invention, the method according to the invention enables the control of the complex variable "quality". The glass quality is determined depending on the type of glass and / or the system for melting and / or refining glass as a function of at least one of the following control variables: volumetric number of bubbles, bubble size distribution and content of the gases dissolved in the glass melt. For this purpose, at least one first detection device is provided for the control device, which detects at least one control variable, in particular one of the control variables mentioned. The target values are predetermined for the control device by detecting the controlled variables. To feed the actual values into the control system, the control device provides a second detection device which can detect at least one process variable, in particular one of the following process variables:

• - temperature
• - atmospheric residual pressure in the refining chamber
• - Heating capacity
• - Heating output in upstream and / or downstream process steps
• - Moisturized
• - Mixed situation
• - batch form
• - Volume flow through the glass nozzles
• - Glass stand in the melting tank and / or in the refining tank and / or in the channel and / or in the stir pan
• - viscosity of the glass
• - Throughput of the glass
• - partial pressure of oxygen in the glass
• - water content of the glass
• - Oxygen partial pressure of the exhaust gas
• - furnace pressure in the melting tank
• - foam height
• - shape of the foam
• - location of the foam
• - Pressure and / or volume flow of the protective gas
• - Bubble formation rate in the melting tank
• - stirrer speed
• - Oxygen partial pressure on precious metal components.

To convert the captured size to a The invention sees a signal at least one first processing device in which at least one of the process variables can be processed. A comparison with corresponding values, for example other locations have been identified also enables monitoring of the process.

The control device according to the invention is the further characterized by at least one first output device, which can output at least one of the process variables. To this In this way the signal can be passed on and there is possibility to query the forwarded value so that by comparison of the forwarded processed a control option with the recorded value for working together given the acquisition, processing and output device is.

To the sizes of interest The control device according to the invention provides a particularly simple way of detecting before that the detection device at least one measuring device for measuring at least one control, process or manipulated variable.

The control device according to the invention is advantageous for various Systems can be used, in particular the invention offers the possibility of the control device with any of the following components To use controlled system: The plant for melting and / or refining Glass can be a loading machine, a melting tank, an oven, a refining, a refining crucible, a riser pipe, a horizontal refining chamber, a downpipe, one Conditioning part, a device for the injection of surface-active substances, a Device for introducing protective gas, a homogenization system, a feeder, a device for hot forming, a cold end, a blow nozzle, a pump and a stirrer include.

The measuring device according to the invention can at least one of the following locations: melting furnace, refining, refining crucible, Riser pipe, horizontal refining chamber, Downpipe, conditioning part, homogenization system, feeder, Establishment for the hot forming or cold end. The position of the measuring device is therefore advantageous variable, so that several measuring devices for locally resolved control possible are. As long as there is a minimum amount of information in one of the locations mentioned is determined, the further measurement data acquisition is in no way limited.

For setting at least one manipulated variable the control device according to the invention furthermore an adjusting device. This enables even with a single setting device, if necessary to complex Way determined in the control device, namely the a manipulated variable in which Feedback process and so make the actual regulation.

Just like the position of the measuring device the position of the adjusting device is variable, so that it is spatially large of the controlled system, the manipulated variable can be coupled in at several points. According to the invention Setting device provided at at least one of the following locations: Melting tank, refining chamber, refining crucible, Riser pipe, horizontal refining chamber, Downpipe, conditioning part, homogenization system, feeder or facility for the hot forming.

• – Wasserzugabemenge in das Gemenge
• – Wassereindüsungsmenge in die Oberofenatmosphäre
• – Oxidationsmittelzumischungsmenge für fossile Brennstoffe
• – Volumenstrom durch die Blasdüsen
• – Verhältnis zwischen Brennstoff und Oxidationsmittel
• – Position und/oder Taktzahl und/oder Pausenzeiten und/oder Stoffmenge pro Takt der Einlegemaschine
• – Volumenstrom und/oder Zusammensetzung der Eindüsung oberflächenaktiver Substanzen
• – Leistungsdichte im Schaum
• – Durchsatz des Glases
• – Saugleistung der Pumpen
• – Leckraten
• – Höhe der Läuterbank
• – Heizleistung
• – Druck und/oder Volumenstrom des Schutzgases
• – Rührerdrehzahl
• – Gaszusammensetzung an der glasabgewandten Oberfläche von Edelmetallbauteilen.

The control described so far detects the manipulated variables indirectly from deviations of the target from the actual values. Irrespective of this, the invention provides a further control option for the manipulated variables, in that at least one of the following manipulated variables can be recorded directly in a third detection device:

• - amount of water added to the batch
• - amount of water injected into the upper furnace atmosphere
• - Amount of oxidizing agent for fossil fuels
• - Volume flow through the blow nozzles
• - Relationship between fuel and oxidant
• - Position and / or number of cycles and / or break times and / or quantity of material per cycle of the loading machine
• - Volume flow and / or composition of the injection of surface-active substances
• - Power density in the foam
• - Throughput of the glass
• - Pump suction power
• - leakage rates
• - Height of the refining bench
• - Heating capacity
• - Pressure and / or volume flow of the protective gas
• - stirrer speed
• - Gas composition on the surface of precious metal components facing away from the glass.

In at least one second processing device at least one of the manipulated variables can be processed. This makes a comparison with corresponding values, e.g. on other measuring locations possible, and the manipulated variable itself can thus be compared.

In at least one second output device at least one of the manipulated variables can be output. This is analogous to the first output device for outputting a process variable the possibility for the Forward the signal and for given a query of the forwarded signal, so that a Control of the scheme can be made.

The control device further comprises a compensation device which can compensate for the influence of disturbance variables such as, in particular, day / night fluctuations, fluctuations in air pressure, fluctuations in air humidity on the manipulated variables and / or controlled variables. The invention thus provides a particularly simple way of relieving the pressure on the control device by filtering out disturbance variables from the environment. The regulation therefore does not have to be designed for such uncertain, difficult to calculate fluctuations. Therefore, the invention offers the possibility for a finer tuning of the scheme that the according to is more precise.

In addition to capturing setpoints The measurement effort can be removed from the process by assigning fixed setpoints be reduced. The control can be done using various parameters can be adapted to different strategies without the control device changed even in its structure must become. Therefore the invention sees an archiving device in a particularly simple manner which the setpoints for Controlled variables and / or Can archive parameters of the control device. This saved Setpoints are also compared with actual values across the various control loop levels linked away, so that it works in the same way as the recorded setpoints in the Control device can be processed.

Using an input device the current production target can be entered. This grasping the immediate target size enables an evaluation with regard to the actual implementation of the proposed Control target by comparing the entered current production target with the result of the production and thus an adjustment of the Regulation if there are deviations. On the other hand, can be different Process goals selected be so that the scheme is variable to different requirements can be set without the control device or the underlying Change procedure yourself to have to.

In this regard, the invention offers the big one The advantage of being able to save target-oriented values permanently by the archiving device the target values for the controlled variables and / or the parameters of the control devices according to the current Can archive the production target.

Because the control device according to the invention, as described above, extremely variable can be used, the control can be implemented in different versions the system can be used, for example in a device for melting and / or refining, in a vacuum melting and / or purification unit in a high-frequency heatable Melting and / or Läuteranlage or in a directly electrically heatable melting and / or refining plant.

The method according to the invention not only serves as described above, the execution of the control concept according to the invention in the control device, but also the assessment of controllability and the control behavior of the production plant and its stability in the design phase of the plant. This is achieved in that the operating behavior of the plant for melting and / or refining Glass is determined and / or simulated by simulation calculations. By creating a simulation model of the real production plant can then control behavior by analyzing the simulation calculations individual components and / or the entire system in simple Way are derived. The invention thus offers the possibility of Align the regulation in advance with the reality of the process.

The result of the simulation can to determine the control behavior of at least one process level be used. Across from The purely empirical procedure of coordinating the regulation can be based on this way a reliable Alignment with significantly fewer iteration steps to adjust the Parameters are made. Deviations from specified target values can early recognized and according to the degree of deviation according to glass and / or process-dependent Weighting regulations are counteracted (statistical process control).

Such coordination can be advantageous according to the invention Way done particularly quickly by at least one process level from the result of the simulation to determine the control behavior a real-time control model is derived.

To be able to vote quickly with significantly fewer iteration steps for the method according to the invention The invention sees further possibilities for extensive use before: so the result of the simulation can be used to determine the control behavior the entire plant for melting and / or refining glass become. At the same time, however, there is also the possibility of determining the at least one manipulated variable from at least a setpoint and at least one actual value is empirically developed To apply the regulation. The manipulated variable is advantageously in the method according to the invention using at least one target value and at least one actual value one on a phenomenological Model-based regulation determined. To determine the manipulated variable further one on a chemical and / or physical model based rule can be applied. It is also possible to have one To apply regulation, which consists of a combination of an empirical developed regulation and / or one on a phenomenological Model-based regulation and / or one based on a chemical and / or a physical model based rule becomes.

By setting the parameters in each control loop the regulations for determining the at least one manipulated variable based on a comparison with the process data to the current situation adjusted, the advantage is created in a simple manner, that the control reacts variably to the current situation.

The process data used for the comparison can be derived from the current production. The control can thus be coupled with a process control system; this is particularly advantageous since the necessary data are already available in the process control system. However, the control according to the invention is not dependent on the presence of a process control system: those for the Ver Process data used immediately can also be determined in experiments.

In the previous description considered the case that the control device according to the invention or Procedure for the regulation of glass quality is used for a given process goal. The invention offers about it beyond the possibility of in addition to the glass quality regulate the change in production parameters. In this way can also automate a reliable product change with the invention carried out become.

The invention is described below Reference to the attached Drawings described in more detail. The same components marked on all drawings with the same reference numerals.

Show it:

1 schematic representation of a regulation according to DIN 19226,

2 schematic representation of a plant for melting and / or refining glass,

3 Flow chart of the regulation according to the invention,

4 Principle sketch of a refining unit,

5 schematic representation of an absolute pressure control,

6 schematic representation of a differential pressure control,

7 schematic representation of a glass level control,

8th Flow chart for the regulation of the vacuum purification,

9 Flow chart for the regulation of high-frequency purification.

Out 2 is a general scheme for a system 500 for melting and / or refining glass. The attachment 500 consists of a melting tank 510 , a lauter tun 520 and a gutter 530 , The system shown 500 has a separate melting tank 510 and lauter tun 520 on; in principle, however, both can also be combined into a tub or divided into further sections. As the starting material for the glass melt that is as bubble-free as possible 600 becomes the batch 650 is in the melting furnace 510 given up. In the melting tank 510 melts the batch 650 on; so that the glass melt 600 is formed. The melt 600 gets into the lauter tun later on 520 in which removing the bubbles from the glass melt 600 is carried out. The purified glass melt 600 is over the gutter 530 for further processing.

In 3 the general sequence of control according to the invention is shown. The system for refining and / or melting glass described above forms a controlled system. The controlled variables, process variables and, if applicable, manipulated variables can be recorded at different locations on the controlled system. For this purpose, the controlled system with at least one measuring device 13 Mistake. The measuring device 13 can be a compensation device 14 upstream to eliminate external influences.

The from the measuring device 13 certain sizes are used by detection devices 10 . 11 . 12 added. With a detection device 10 control variables, i.e. setpoints, are recorded. With another detection device 11 Process variables are recorded in a processing facility 21 processed and then by means of an output device 31 can be spent. In another detection device 12 can directly record manipulated variables in a processing facility 22 processed and via an output device 32 be issued.

The control device according to the invention 1 includes a high-level control device 50 , as well as a control device at a low level 60 , The recorded setpoints and actual values are stored in a linking device 70 linked across the control loop levels. The control device at a high level 50 the setpoints and actual values can be supplied so that in the control device 50 Control variables are determined using a default device 55 can be spent. The control device at a high level 50 also includes a further default device 56 , by means of the default device 56 from the to the control device at a high level 50 forwarded setpoints and actual values setpoints for a control device at a low level 60 be passed on. From setpoints and actual values, which the control device at a low level 60 from the link device 70 receives and / or from setpoints that the control device at a low level 60 from the control device at a high level 50 via the default facility 56 receives, are in the control facility at a low level 60 Control variables determined.

The control device 1 further comprises an input device 95 , Via the input device 95 process targets can be entered in the archiving facility 90 get saved. Depending on the process goals, the archiving device can also provide setpoints and parameters for the control devices. In addition to the setpoints recorded as described above, the linking device 70 also archived setpoints from the archiving facility 90 processed. The parameters in the control equipment 50 and 60 the control device 1 these control devices are used 50 and 60 from the archiving facility 90 depending on that in the input device 95 entered process target provided.

In the control device, manipulated variables are determined in different ways, depending on the respective requirements, from recorded and / or archived setpoints or actual values. The manipulated variables who with the help of an adjustment device 80 into the components of the plant for melting and / or refining glass 2 fed back.

The regulation according to the invention can be carried out in different ways Processes are used. The following are important points of view represented a process control according to the invention, before going into detail on various exemplary embodiments becomes.

Already when designing one Unterdruckläuteranlage must be assessed to what extent a significant reduction of the residual gas content additionally to eliminate the bubbles. Is a bigger reduction the residual gas content, one will prefer to separate the process steps. The general guideline is the idea that the glass melt preferably must not be converted into foam or precursors. Otherwise is the repatriation of Foam into a homogeneous melt is very time consuming. The glass bath surface should also preferably be little covered with foam to facilitate gas exchange on the glass bath surface. It should also be noted that the lowest to be set atmospheric pressure by the vapor pressure of the most volatile Glass component is determined. In general, therefore Pressure at approx. 1500 ° C for example, do not drop significantly below 100 mbar.

One of the most important design parameters is the pressure-time curve p (t), which is traversed by a volume element of the glass melt. The time t to reach the residual pressure p _R on a pressure reduction section l is m at a throughput. a cross-sectional area A and the density ρ of the melt given by

During this time, the air pressure is reduced from the atmospheric pressure p _A to the residual pressure p _R.

The pressure-time curve is to be set so that on the way to the residual pressure there is no foam in the volume of the supply pipe arises. To do this at a given mass flow rate m. the length of the pressure reduction section l and / or the cross-sectional area A can be enlarged. About that In addition, in the unit part that serves to remove bubbles, make sure that no new bubbles are created, but only the existing bubbles are enlarged and these slightly can escape from the melt.

• – Volumendichte der Blasen
• – Größenverteilung der Blasen
• – Zusammensetzung der Blasen
• – Konzentration bzw. Partialdrücke der in der Schmelze gelösten Gase
• – Konzentration des Läutermittels
• – Temperatur des Glases
• – Viskosität des Glases
• – Durchsatz
• – zeitlicher Verlauf des Druckabfalls.

At the entry of the glass into a refining unit, in particular into a vacuum refining unit, the following state variables should be measured or known:

• - Volume density of the bubbles
• - Size distribution of the bubbles
• - composition of the bubbles
• - Concentration or partial pressures of the gases dissolved in the melt
• - concentration of the refining agent
• - temperature of the glass
• - viscosity of the glass
• - throughput
• - Time course of the pressure drop.

When entering a vacuum cleaning system the bubble density must be within certain ranges: is the bubble density is too high, there is a risk of foam formation in the Riser. On the other hand, the bubble density must not be too low, otherwise no significant degassing can be achieved.

die durch die isotherme Vergrößerung

und durch die im allgemeinen wesentlich wichtigere Vergrößerung f_Diff >> f_BM durch Diffusion von Gasen aus der Schmelze. Je nach Betrag der oben eingeführten Variablen, insbesondere aber bei zu hoher Blasendichte und Temperatur bzw. bei niedriger Viskosität, kann die Blasenvergrößerung so stark sein, dass die Schmelze in eine schaumartige Struktur umgewandelt werden kann. Außerdem wird durch eine geringe Viskosität die Blasenneubildung erleichtert. Dieser im allgemeinen unerwünschte Zustand kann bei einer gegebenen Aggregatform dadurch kontrolliert werden, dass man den Durchsatz oder die Glastemperatur absenkt.When the glass passes through a vacuum unit, over time the ambient pressure decreases to the set residual pressure (vacuum), whereby the bubbles present in the melt can be greatly inflated. The bubble enlargement f as a ratio of the starting radius r _A to the ending radius r _R at the residual pressure p _R is given by

by the isothermal enlargement

and by the generally more important magnification f _Diff >> f _BM by diffusion of gases from the melt. Depending on the amount of the variables introduced above, but in particular if the bubble density and temperature are too high or the viscosity is low, the bubble enlargement can be so strong that the melt can be converted into a foam-like structure. Low viscosity also makes it easier to form new bubbles. This generally undesirable state can be controlled for a given form of aggregate by lowering the throughput or the glass transition temperature.

• – Restdruck der Atmosphäre
• – Glasbadtiefe
• – Schaumhöhe
• – Temperatur des Glases
• – Viskosität des Glases
• – Rate verdampfender Glasbestandteile.

The following sizes must be measured or known in the vacuum ring unit:

• - residual pressure of the atmosphere
• - glass bath depth
• - foam height
• - temperature of the glass
• - viscosity of the glass
• - Rate of evaporating glass components.

Depending on the type of glass, temperature and Vacuum only a limited number of bubbles sufficient on the glass bath surface can leave quickly, foam can form. Especially the Process for reducing the gas content must be regulated that the foam generation rate and the foam destruction rate increase preferably low and stable foam heights leads. Additional heating of the foam can help accelerate foam breakdown useful his. this leads to because of the lowering of viscosity for an accelerated drainage of the glass back to the glass bath surface, as well to an elevated Evaporation of the thin Glass films, which promotes their bursting open. In addition, other substances can be used for further Increasing the Evaporation - connected with an increase the surface tension - used become. Through sensors can Foam thickness, shape and location of the foam cover are recorded.

• – Volumendichte der Blasen
• – Konzentration und/oder Partialdruck der Gase in der Glasschmelze.

At the exit of the glass from the vacuum unit, the following sizes must be measured or known:

• - Volume density of the bubbles
• - Concentration and / or partial pressure of the gases in the glass melt.

der totale Druck der gelösten Gase in der Schmelze sind. Statt des totalen Drucks kann auch der Partialdruck p_i einer kritischen Gaskomponente verwendet werden.These variables are used as actual values for determining the global quality function f _M and compared with the target value f _{M, F.} Both sizes are defined as follows: f = a · N + b · p dead Equation 9 where a and b weighting factors depending on the type of glass and the process as well as N the bubble density and

are the total pressure of the dissolved gases in the melt. Instead of the total pressure, the partial pressure p _{i of} a critical gas component can also be used.

By phenomenological and / or empirical Models and partly through model-based regulations and combinations from this it is achieved that the volume density of the bubbles and possibly. the concentration loosened Gases at the end of the refining unit remains below product-specific predetermined values.

To record process data Sensors needed. This includes for determining the hygrometer and IR spectrometer, for measuring the temperature thermocouples and pyrometers, for determining of the volume flow through the Rotameter or massflow controller or pressure transmitter. The viscosity of the glass can be determined using the vibrating rod or by resonance process from Marimex be determined. To determine the redox potential of the glass an oxygen partial pressure probe can also be used can determine the partial pressure of oxygen in the exhaust gas. For the determination of the oxygen partial pressure in the exhaust gas also comes a laser spectrometer the company Bernd in question. The batch location and batch form can be by Acquisition with one or more cameras with connected image evaluation (for example using a system from STG, Cottbus) be determined. Using a rod train with image evaluation the number of bubbles in the glass can be determined. The glass stand can with a platinum contact organ pipe using a laser over a electrical contact or radioactive. The foam height can also about determined a platinum contact organ pipe and using a CCD camera become. The shape and location of the foam are the same as determines the shape and location of the batch. The throughput of the glass results from an integral of the insert or the glass drain. A pressure transducer with transmitter can be used to measure the negative pressure be used.

The heating output can be controlled via a Transducer for electrical quantities, in particular measure the voltage, current, power or frequency. The pressure and volume flow of the protective gas can be controlled via a Determine pressure transmitter or massflow controller. The stirrer speed can be determined using a tachometer.

Also the partial pressure of oxygen Precious metal components must be determined. This comes with an known oxygen partial pressure sensor (pO2 sensor; measurement measured by voltammetry, for example.

In order to carry out the process in a stable manner and to keep the number of bubbles in the product safely below a certain limit value, at least one of the input variables listed in Table 1 for the multiple input multiple output model (MIMO model) is required. The one used in Table 1 Abbreviation SW means melting furnace. With the abbreviation LW the term lauter tun is abbreviated. UD means vacuum unit, with LK the term refining chamber is meant. The redox ratio indicates the concentration of trivalent and / or pentavalent ions, in particular trivalent and / or pentavalent ions from refining aids such as arsenic and antimony, in relation to the concentration of oxygen. The term rod pull is understood to mean a device which enables the production of glass rods by pulling them out of the melt. Table 1: Input variables for the MIMO model and sensors for their measurement.

The regulation should affect at least one of the variables listed in Table 2. Table 2: Controlled variables and corresponding actuators with an explanation of the manipulated variable

The abbreviation SAR used in Table 2 means melting unit, with the abbreviation EZH is an electrical Additional heating designated. Under the term feeder one Device understood, which is in the direction of the glass located at the end of the melting or refining tank. The feeder comprises an external limitation, which can be designed as a cylinder. Inside the feeder the glass can be melted through a feeder needle refining tank promoted become. The feeder settings essentially include the setting the temperature and the stroke of the feeder needle.

The control loop is linked using at least one of the following strategies:
PID, fuzzy, neural networks, adaptive controls and model-based control strategies such as MIMO control in particular.

Using the following examples the use of the regulation according to the invention for the regulation of bubble growth, the regulation of degassing, the regulation of Glass level and furnace pressure in a vacuum unit, the regulation of the foam height and structure, and the regulation of the number of bubbles described.

The goal in controlling bladder growth is to remove all the blisters. To do this, the bubbles get a sufficiently high buoyancy speed relative to the surrounding glass melt. The rate of buoyancy is given by equation 1. Increasing the temperature increases the partial pressure of a gas in the melt, which can be released from a refining agent added to the glass melt. Furthermore, the viscosity of the melt is reduced when the temperature rises. Because of the difference in partial pressure, the refining gas diffuses into existing bubbles. This increases their diameter, which leads to an increased bubble ascent rate according to Stokes law (equation 1).

The same can be achieved if you instead of or in addition to a change in temperature atmospheric Residual pressure in the refining unit lowers. This is the total pressure and also the partial pressures of the gases contained therein, which in turn because of the Difference in pressure between bubbles and the surrounding melt leads to an enlarged bladder.

The bubble growth rate can be a function of temperature and / or atmospheric Residual pressure measured or from the substance data, in particular the solubility, the diffusion coefficient and the concentrations are calculated.

In 4 the spatial conditions of a refining unit are outlined. If one knows the mean starting bubble radius in front of the refining unit, one can calculate from the known data for the size growth after which time t ₁ the bubbles have reached a certain size. This time must approximately coincide with the time t that the bubbles reach due to the flow velocity of the glass vs and their buoyancy velocity v _A , where

With a known pipe cross section A and a volume flow dV / dt, the mean flow velocity vs is given by assuming a piston flow

After passing through the vertical section of height h, the bubbles must have become so large that they can safely leave the melt on the horizontal section L with glass height d due to their buoyancy (cf. 4 ). This means that the maximum bubble rise time t _max in the horizontal refining part must be less than the average throughput time t _L. This can be used to estimate how many bubbles reach the glass bath surface, where they burst and leave the melt.

Related to bladder growth it should be noted that to carry out the purification that Bubble growth must be kept within certain limits. If the bubble growth is too small, it may be too small because of the Buoyancy speed not enough bubbles from the melt be removed. If the bubble growth is too large, however, there is the risk that the proportion of bubbles per unit volume of the melt gets too big. This reduces the effective density of the melt too much, which to an undesirable Influencing the convection flow in the melting and refining area, as well as to tear off the glass column lead in the vacuum part can.

A too high proportion of bubbles per unit volume the melt leads to a reversal of the share of glass to gas in the sense that Foam can arise in a wide variety of forms. This is an undesirable one Operating state since the return of Foam in glass is very time consuming, and the amount of foam only with Reduced again with the help of physical or chemical methods can be. In particular, the heating comes to increase the Evaporation or the injection of substances that increase surface tension in question. Foaming is also negatively affected, if the formation of new bubbles starts due to insufficient residual pressure.

As main parameters for influencing the bubble density after the refining aggregate the following sizes are available available: the length L of the refining line with a fixed cross-sectional area, the volume flow of the glass dV / dt and the atmospheric residual pressure in the refining unit. About that In addition, the bubble growth and rate of buoyancy the bubbles by adding refining agent as well as by adjusting the temperature. Furthermore it is necessary to regulate the bubble growth, the size distribution and the volume density of the incoming bubbles as well as the content of the dissolved in the melt At least approximately gases to investigate.

Darin bezeichnet r_B den mittleren Blasenradius, N_B die Blasendichte, D_i(T) den Diffusionskoeffizienten, Δp_i den Partialdruckunterschied zwischen Blasen und umgebender Schmelze für die Gasart i und Δt die Dauer der Einwirkung.In addition to eliminating the bubbles, the proportion of gases dissolved in the melt should be significantly reduced. The degassing control serves this purpose. The mass flow dm / dt between the bubbles present in the melt and their surroundings is proportional to

Therein, r _B denotes the mean bubble radius, N _B the bubble density, D _i (T) the diffusion coefficient, Δp _i the partial pressure difference between bubbles and the surrounding melt for the gas type i and Δt the duration of exposure.

It can be seen in Equation 13 that the extracted amount of gas Δm the higher the longer the process takes the higher the inner exchange area the bubbles (bubble density and bubble surface), the greater the pressure difference and the higher the temperature is because the diffusion coefficient increases with Temperature also rises. These are the most important Control variables for Regulation of degassing.

By default, however, the starting bubbles can cannot be easily influenced. As for the regulation of bladder growth is also for regulation of the degassing required, the size distribution and volume density of the incoming bubbles and the content of the gases dissolved in the melt at least approximately to know. For this purpose, the melt is regularly tested, as already mentioned above taken and the content of dissolved Gases and bubbles examined.

In another embodiment can however the number and size distribution of the starting bubbles: the temperature in the Melting range varies specifically. Another, independent option consists of before or at the entry of the glass into the refining unit targeted bubbles in a certain size distribution and density produce. This can be done, for example, by fine nozzles pulsed glass injected into melt.

Another option is the targeted one Exploiting electrochemical reactions, for example on platinum, that are known from the literature.

Because the bubbles are removed from the process is the time for the size growth the bubbles confined. This leaves largely independent control variables for the control degassing especially the starting bubble density and the average bubble radius.

The following embodiment describes the Regulation of the glass level and the furnace pressure in a vacuum unit.

The height of the glass stand in one Unterdruckläuteraggregat with vacuum part results from the density of the glass, the height of the refining bench and that in the refining part set atmospheric Residual pressure.

A predetermined pressure difference can can be regulated in the following way, for example: as control variables for the furnace pressure in a vacuum cleaner unit can be used:

- the Absolute pressure in the refining unit

- the Differential pressure between air pressure and the pressure in the refining unit, or

- the Glass stand in the refining unit.

These are also examples for regulations, that can be done in a low level controller.

According to 5 the absolute pressure in the vacuum unit is measured with a pressure sensor. This signal is sent to a controller via a transmitter, which has a fixed setpoint. The controller controls a control valve that regulates the inflow of false air and thus forms a so-called controllable leak.

In contrast to in 5 The absolute pressure control shown is in accordance with a differential pressure control 6 with a differential pressure measurement, the differential pressure between the vacuum unit and the outside atmosphere is regulated. This signal is sent to a controller via a transmitter, which has a fixed setpoint. The controller controls a control valve that regulates the inflow of false air and thus forms a controllable leak. The absolute pressure control and the differential pressure control therefore differ only in the type of measuring device used 13 , which is designed as a pressure sensor in the discussed embodiment.

With the glass level control, as in 7 shown, measured with a glass level sensor the glass level in the vacuum unit. This signal is sent to a controller via a transmitter, which has a fixed setpoint. The controller controls a control valve that regulates the inflow of false air (controllable leak). The varying pressure in the vacuum unit leads to a varying glass level as a result of the hydrostatic pressure. The glass level control is therefore connected to the pressure control, which, as shown above, can be implemented as an absolute pressure or differential pressure control.

The differential pressure or absolute pressure control can also be used to control the furnace pressure: for refining in units at normal pressure is the atmospheric pressure in the refining chamber relevant. This results from the weather-dependent pressure of the surrounding atmosphere, the fed through the burner Amount of gas discharged Exhaust gas volume and the leak rate. At the same time, the partial prints the gases in the furnace atmosphere by setting an equilibrium in the amount of gas supplied and removed kept stable. The basic execution of the regulation of pressure in the furnace is carried out with differential pressure or absolute pressure regulators.

Regulation of the foam height

The foam height in the refining chamber can be determined by mechanical sensors, by measuring thickness with radionuclides or by interaction detected with electromagnetic or acoustic waves.

By introducing chemical substances, of thermal energy, pressure changes or mechanical movement the foam decomposition rate can be varied.

The following strategy is used, for example, to regulate the number of bubbles in the vacuum purification: a predetermined temperature profile is maintained by means of the heating power of various burners via a MIMO temperature controller. An independent control loop regulates the glass level and furnace pressure in the refining chamber by adjusting the height of the refining bench and the suction power of the vacuum pump. The setpoints for glass level, furnace pressure and the temperature profile to be set are determined from a higher-level control loop. The higher-level control loop calculates the setpoints for the lower-level control loops from the currently measured number of bubbles and a corresponding setpoint, as shown in 8th is illustrated.

In the case of in 9 Control for high-frequency purification shown are available as energy sources, both furnace furnace and the electrical power of the coil. Both energy inputs affect the temperatures in the glass bath and in the upper furnace. A MIMO controller, which calculates the required output of the burner and the coil, is therefore required to control a desired temperature profile in the vault and melt. This controller can obtain the setpoint values for the temperature profile from a higher-level control circuit that controls the number of bubbles or another quality quantity of the glass.

Claims (47)

Control device ( 1 ) for one system ( 2 ) for melting and / or refining glass, characterized in that the regulating device regulating devices ( 50 . 60 ), which form at least two control loop levels. Control device ( 1 ) according to claim 1, characterized in that the control device comprises a linking device ( 70 ), which can link a large number of setpoints and / or actual values over several control loop levels, in particular in a so-called multiple input multiple output (MIMO) system. Control device ( 1 ) according to claim 1 or 2, characterized in that the control loop levels are arranged hierarchically, the at least one control device ( 50 ) of the higher-level control loop level, a first default device ( 56 ) with which the at least one control device ( 60 ) of the respective lower control loop level setpoints can be specified. Control device ( 1 ) according to claim 3, characterized in that the at least one control device ( 50 ) of the higher-level control loop level, a second default device ( 55 ) with which direct manipulated variables can be specified. Control device ( 1 ) according to claim 3 or 4, characterized by a default device which the first default device ( 56 ) for setting the setpoints and the second setting device ( 55 ) for specifying the manipulated variables. Control device ( 1 ) according to one of the preceding claims, characterized by at least one first detection device ( 10 ), which can record at least one controlled variable, in particular one of the following controlled variables: - volumetric number of bubbles - bubble size distribution - content of the gases dissolved in the glass melt. Control device ( 1 ) according to one of the preceding claims, characterized in that the system ( 2 ) for melting and / or refining glass at least one insertion machine, at least one melting tank, at least one top furnace, at least one refining trough, at least one refining chamber, at least one refining crucible, at least one riser pipe, at least one horizontal refining chamber, at least one downpipe, at least one conditioning part, at least one device for injecting surface-active substances, at least one device for introducing protective gas, at least one homogenization system, at least one feeder, at least one device for hot forming, at least one cold end, at least one blow nozzle, at least one pump and at least one stirrer. Control device ( 1 ) according to one of the preceding claims, characterized by at least one second detection device ( 11 ), which can record at least one process variable, in particular one of the following process variables: - temperature - atmospheric residual pressure in the refining chamber - heating power - heating power in upstream and / or downstream process steps - batch moisture - batch batch - batch shape - volume flow through the blow nozzles - glass level in the melting tank and / or in the refining tank and / or in the channel and / or in the stir pan - viscosity of the glass - throughput of the glass - oxygen partial pressure of the glass - water content of the glass - oxygen partial pressure of the exhaust gas - furnace pressure in the melting tank - foam height - shape of the foam - Position of the foam - Pressure and / or volume flow of the protective gas - Bubble formation rate in the melting tank - Stirrer speed - Oxygen partial pressure on precious metal components. Control device ( 1 ) according to one of the preceding claims, characterized by at least one first processing device ( 21 ), in which at least one of the process variables can be processed. Control device ( 1 ) according to one of the preceding claims, characterized by at least one first output device ( 31 ), which can output at least one of the process variables. Control device ( 1 ) according to one of the preceding claims, characterized in that at least one detection device at least one measuring device ( 13 ) for measuring at least one controlled variable. Control device ( 1 ) according to one of the preceding claims, characterized in that the measuring device ( 13 ) can be arranged at at least one of the following locations: melting tank, floor drains, upper furnace, refining trough, refining chamber, refining crucible, riser pipe, horizontal refining chamber, downpipe, conditioning part, homogenization system, feeder, device for hot forming, cold end. Control device according to one of the preceding claims, characterized by at least one setting device ( 80 ) for setting at least one manipulated variable. Control device ( 1 ) according to one of the preceding claims, characterized in that the adjusting device ( 80 ) can be arranged in at least one of the following locations: melting tank, upper furnace, refining trough, refining chamber, refining crucible, riser pipe, horizontal refining chamber, downpipe, conditioning part, homogenization system, feeder, device for hot forming. Control device ( 1 ) according to one of the preceding claims, characterized by at least one third detection device ( 12 ), in which at least one of the following manipulated variables can be recorded: - amount of water added to the batch - amount of water injected into the upper furnace atmosphere - amount of oxidizing agent for fossil fuels - volume flow through the blowing nozzles - Relationship between fuel and oxidizing agent - Position and / or number of cycles and / or break times and / or quantity of substance per cycle of the loading machine - Volume flow and / or composition of the injection of surface-active substances - Power density which is generated by the foam-destroying energy form - Suction power of the pumps - Leakage rates - Height of the refining bench - Heating power - Pressure and / or volume flow of the protective gas - Stirrer speed - Gas composition on the surface of precious metal components facing away from the glass Control device ( 1 ) according to one of the preceding claims, characterized by at least one second processing device ( 22 ), in which at least one of the manipulated variables can be processed. Control device ( 1 ) according to one of the preceding claims, characterized by at least one second output device ( 32 ), which can output at least one of the manipulated variables. Control device ( 1 ) according to one of the preceding claims, characterized by a compensation device ( 14 ), which can compensate for the influence of disturbance variables, such as in particular day-night fluctuations, fluctuations in air pressure, fluctuations in air humidity, on the manipulated variables and / or control variables. Control device ( 1 ) according to one of the preceding claims, characterized by an archiving device ( 90 ), which can archive the setpoints for the controlled variables and / or the parameters of the control devices. Control device ( 1 ) according to one of the preceding claims, characterized by an input device ( 95 ), through which the current production target can be entered. Control device ( 1 ) according to one of the preceding claims, characterized in that the archiving device ( 90 ) the target values for the controlled variables and / or the parameters of the control devices ( 50 . 60 ) can archive according to the current production target. Device for melting and / or refining with a control device ( 1 ) according to one of the preceding claims. Vacuum melting and / or purification unit with a control device ( 1 ) according to one of claims 1 to 21. High-frequency heatable melting and / or refining plant with a control device ( 1 ) according to one of claims 1 to 21. Directly electrically heatable melting and / or refining plant with a control device ( 1 ) according to one of claims 1 to 21. Procedure for controlling an installation ( 2 ) for melting and / or refining glass, which comprises the following method steps: detecting at least one controlled variable, detecting at least one process variable corresponding to the controlled variable, determining at least one manipulated variable for controlling the process variable, characterized in that at least one manipulated variable is determined in a control system , which comprises at least two control loop levels, the respective higher control loop level of the respective lower control loop level specifying the target values. A method according to claim 26, characterized in that a Numerous setpoints and actual values across several control loop levels linked together become. A method according to claim 26 or 26, characterized in that that the Regulation using a MIMO (multiple input multiple output) algorithm carried out becomes. Method according to one of claims 26 to 28, further characterized by the following method steps: detecting at least one controlled variable which can be used as a recorded target value, recording at least one process variable, processing the process variable, outputting the processed process variable as an actual value, linking recorded target values and actual values via Control loop levels, transfer of the setpoints to a control device ( 50 ) at a high control loop level, specification of the setpoints by a control device ( 50 ) at a high control loop level to a control device ( 60 ) at a lower control loop level, forwarding the actual values to the control device ( 60 ) at a lower control loop level, determining a manipulated variable from the setpoints and actual values in the control device ( 60 ) at a lower control loop level output of the manipulated variable to a setting device ( 80 ), Setting the manipulated variable in the process. A method according to claim 29, characterized in that saved Setpoints available which are also provided with actual values across control loop levels connected become. A method according to claim 30, characterized in that the stored setpoints correspond to the process target. Method according to one of claims 29 to 31, characterized in that manipulated variables directly from a control device ( 50 ) can be specified at a high control loop level for setting. Method according to one of claims 29 to 32, characterized in that that at least a manipulated variable is recorded, which is processed and for the setting is output as a processed manipulated variable. Method according to one of claims 26 to 33, characterized in that that the glass quality is regulated. A method according to claim 34, characterized in that the glass quality dependent on of the type of glass and / or of the plant for melting and / or refining Glass determined as a function of at least one of the following control variables becomes: - volumetric Bubble number density - Bubble size distribution - Salary the dissolved in the glass melt Gases. Method according to one of claims 26 to 25, characterized in that the operating behavior of the system ( 2 ) for melting and / or refining glass is determined and / or simulated by simulation calculations. Method according to one of claims 26 to 36, characterized in that that this Result of the simulation to determine the control behavior at least a process level is used. Method according to one of claims 26 to 37, characterized in that that for at least a process level from the result of the simulation to determine of the control behavior derived a model for control in real time becomes. Method according to one of claims 26 to 38, characterized in that the result of the simulation for determining the control behavior of the entire system ( 2 ) is used for melting and / or refining glass. Method according to one of claims 26 to 39, characterized in that that for Determining the at least one manipulated variable from the at least one Setpoint and the at least one actual value is empirically developed Regulation is applied. Method according to one of claims 26 to 40, characterized in that that for Determining the at least one manipulated variable from the at least one Setpoint and the at least one actual value one on a phenomenological Model-based regulation is applied. Method according to one of claims 26 to 41, characterized in that that for Determining the at least one manipulated variable from the at least one Setpoint and the at least one actual value one on a chemical and / or physical model-based regulation applied becomes. Method according to one of claims 26 to 42, characterized in that that for Determining the at least one manipulated variable from the at least one A setpoint and the at least one actual value which is a combination of an empirically developed one Regulation and / or one based on a phenomenological model Regulation and / or one on a chemical and / or physical Model based regulation is developed. Method according to one of claims 26 to 43, characterized in that that in for each control loop the parameters of the regulations for determining the based on at least one manipulated variable a comparison with the process data be adapted to the current conditions. A method according to claim 44, characterized in that the for the Comparison of process data used derived from ongoing production. A method according to claim 45, characterized in that the for the Comparison of process data used can be determined in experiments. Method according to one of claims 26 to 46, characterized in that that alongside the glass quality of the Change of production parameters is regulated.