Method for determining the batch thickness in a fully electric glass furnace

Abstract

The present invention relates to a method for recording and evaluating data on the batch ceiling and / or the glass melt in a fully electric cold-top melting furnace for melting glass, as well as the use of the method in a process for manufacturing glass.

Description

The present invention relates to a method for acquiring and evaluating data relating to the mixture ceiling and / or the glass melt, in particular in a fully electric cold-top melting tank for melting glass, and to the use of the method in a method for producing glass.Technical Background / Prior ArtIn order to reduce the CO 2- output in glass production, fully electric melting tanks are increasingly being used in the production of glass and glass ceramic.In fully electric melting tanks, the entire free surface of the glass melt is usually covered with batch. This closed mixture ceiling thermally isolates the glass melt from the top furnace, so that the surface temperature of the glass melt is lowered from about 1400° C. to 1650° C. to about 200° C. to 400° C. This firstly maximizes the melting-in performance and significantly improves the energy efficiency of the melting trough. The significantly colder upper furnace also reduces risks for devices present in the upper furnace, such as inserting machine and upper furnace materials, or lowers the requirements with regard to the thermal load capacity for the construction of the upper furnace.During the operation of fully electric melting pans, therefore, measures are generally taken to ensure a closed mixture surface over the entire surface of the melting bath. For this purpose, the thickness of the mixture ceiling is locally measured and the mixture insert is adapted accordingly.It is possible to determine the batch thickness manually by puncturing with a rod via the lateral insertion opening at points (in time and space). This measuring method is risky for humans as well as processes when the electric tub heater is switched on and requires the use of personnel. In addition, the batch thickness can be measured locally only at one location and only relatively inaccurately.Since the temperature of the mixture ceiling is dependent on the thickness of the mixture ceiling, the thickness of the mixture ceiling can be determined from the measured temperature. WO 80 / 02 833 A1 and U.S. Pat. No. 3,980,460 A describe movable inserts for cold-top troughs, in which an IR sensor or a heat sensor measures the temperature of the mixture ceiling. If an excessively high temperature of the mixture ceiling is detected at certain points, a larger amount of mixture is applied to the mixture ceiling.WO 2024 / 217 987 A1 describes a computer implemented method for measuring the thickness of a batch of materials floating on a molten pool, the method using as input data a set of time scale temperature maps. WO 2024 / 217 697 A1 describes a method for determining a mix deck surface level in an electric glass furnace and a computer program with instructions.Furthermore, there are methods in the prior art for measuring the distance between the mixture ceiling and the feeder and for determining the height of the glass stand in the melting trough and for keeping this constant by regulating the amount of feed. For example, U.S. Pat. No. 4,194,077 A and U.S. Pat. No. 4,302,623 A describe displaceable inserts for a cold-top trough, at the end of which an ultrasonic sensor for measuring the distance from the mixture ceiling is mounted in each case for this purpose.Further gathering of data on the mix ceiling has not previously been considered necessary in the prior art for the operation of a melting tank. At the same time, the increasing importance of electric melting tanks makes it necessary to optimize the operation of such melting tanks.Object of the InventionIt is therefore an object of the invention to provide methods with which the operation of a fully electric melting tank can be optimized and with which it is possible to react to the melting process and to fluctuations in the melting process in particular by locally and temporally matched insertion rates, and to provide stable and energy-efficient methods for glass production.Brief Description of the InventionThe invention relates to a method for acquiring and evaluating data relating to the mixture ceiling and optionally relating to the glass melt and optionally relating to the glass stand in a preferably fully electric cold-top melting tank for melting glass, comprising the following steps:providing at least one sensor 160 for detecting point data and one sensor for detecting surface data for non-contact detection of data relating to the mixture ceiling 150 at at least the end of the boom 120 of an insertion machine at which mixture is applied to the glass melt,repeatedly acquiring and storing (a) data relating to the mixture ceiling 150 during operation of the melting tank 100 with at least the sensor 160, data relating to at least 10 different positions, preferably at least 100 different positions of the mixture ceiling being acquired, and (b) assigning the data to the position of the end of the boom 120 or of the sensor 160, respectively,processing the acquired data and creating a topography map, preferably a global topography map and / or preferably an optimal topography of the mixture ceiling 150.The invention further relates to the use of the determination method according to the invention in a method for producing glass for controlling the admixture insert.DESCRIPTION OF THE FIGURESFIG. 1 schematically shows a cross section through a cold-top melting tank for carrying out the method according to the invention. FIG. 2 schematically shows a top view of a boom of an insertion machine for carrying out the method according to the invention. FIG. 3 schematically shows the measurement of a mixture ceiling or a topography of the mixture ceiling produced therefrom.DETAILED DESCRIPTION OF THE INVENTIONThe invention relates to a method for acquiring and evaluating data relating to the mixture ceiling and / or the glass stand, in particular in a fully electric cold-top melting trough for melting glass, and for using these data for an optimized melting process. Data are determined and processed in this case which relate both to the spatial and the temporal change in the mixture thickness, and a topography of the mixture ceiling can be created.The term "topography" is understood here to mean a description or representation of the three-dimensional structure of the mixture deck surface (cf. FIG. 3 ). The term "global topography" is understood to mean the topography of the mixture surface which changes during the course of the melting process. The term "optimum topography" is understood to mean a topography of the mixture ceiling, which can be determined by means of the method according to the invention and which enables the most stable process and / or the best glass quality for a specific melting process.It was recognized within the scope of this invention that by comprehensive acquisition and evaluation of data on the mixture ceiling and glass stand, the operation of fully electric cold-top troughs can be improved and stabilized.For example, it has been found that the topography of a mixture ceiling allows conclusions to be drawn about flows within the glass melt below. Such flows cannot be measured directly during the running operation of the melting tank, but play a major role for the energy efficiency of the tank, the wear of tank components and also for the quality of the glass.For example, due to the glass flow of the hot glass, locally different melting rates may occur or due to gas formation in the melting process, "vulcan" formation, i.e. outflow of released gases from the melt, may occur. Such effects deteriorate the energy efficiency of the trough and influence the glass flow, which in turn can lead to fast short-circuit paths and thus poor glass quality.By knowing the batch deck topography, such processes can be influenced by adjusting the batch insert quantity spatially and temporally to these processes. For example, the following is possible:A higher insertion rate can be set in areas with a higher melting rate and a lower insertion rate can be set in areas with a lower melting rate.For example, a hexagonal pattern of thin mixture decking sites can be set, which have a distance from one another optimized for the glass viscosity and evaporation rates and through which released gas can escape from the melt.An optimum mixture thickness topography found can be kept constant over time.It has been found in the context of the invention that, in addition to the spatially defined thickness of the mixture thickness, the temporal constancy of the defined local thickness of the mixture ceiling is also decisive for a stable process.The method according to the invention therefore provides for the contactless acquisition of data on the entire mixture ceiling and / or the glass stand and / or the glass melt, in particular in a fully electric cold-top melting trough. The determined data are evaluated and a topography map and preferably a global topography map and / or optimum topography of the mixture ceiling are created. The data or the topography map is acquired at regular time intervals during the operation of the well and the temporal changes in the topography are evaluated and a global topography is created. Furthermore, a topography of the mixture ceiling that is optimal for the respective melting process is determined and this is used to control the local insertion quantity.A cold-top melting trough is understood to mean a continuously operating melting trough for glass, in which no heating of the batch takes place from the upper furnace of the trough during operation.A schematic section through such cold-top melting trough 100 is shown in FIG. 1. The energy for melting the mixture 150 and heating the glass melt 180 is introduced into the glass melt 180 exclusively by electrodes 110.The batch 130 to be introduced is applied to the surface of the glass melt 140 via the boom 120 of an introduction machine. In order to efficiently use the introduced heat, the mixture placed on the surface of the glass melt 140 forms a continuous mixture carpet 150. As shown in FIG. 2, for example, the extension arm 120 of the insertion machine can travel substantially the entire surface of the glass melt 140 and apply a batch 130 to be inserted onto the surface of the glass melt 140 or an existing batch ceiling 150.At least one sensor 160 for detecting point data and one sensor for detecting surface data for contactless measurement of the mixture ceiling and / or the glass stand are attached at least to the end of the boom 120 of an insertion machine.For this purpose, at least one sensor for detecting point data can be used, wherein such a sensor for detecting point data can be selected from the group consisting of radar sensors, ultrasonic sensors, laser triangulation sensors, laser (time-of-flight) sensors or combinations thereof. The point measurement values obtained by means of such a sensor can be used directly for creating the topography map.Furthermore, in addition to one or more point sensors, at least one sensor is used for detecting the distance between surfaces. Such a sensor for detecting surfaces can be selected from the group consisting of, for example, laser scanners, a 3D camera (time-of-flight, LIDAR), laser triangulation with line patterns, an IR camera, a photogrammetry sensor or combinations thereof. The surface data obtained can be used directly or by combining overlapping partial surface data to create the topography map.The combinations of at least one sensor for capturing point data and at least one sensor for capturing surface data are used and the obtained data are used for creating the topography map.According to an embodiment of the invention, one or more sensors may be housed in a water- and / or air-cooled housing.The sensor data can be acquired during the set placement process. Alternatively or additionally, a cantilever 120 can also travel along the surface of the glass melt 180 without the introduction of batch, in order to only record measurement data by means of a sensor 160 attached, for example, to the end of the cantilever 120.The measurement data obtained are processed together with the respective position of the boom 120 and a topography of the mixture ceiling is preferably created (cf. FIG. 3 ). Such a topography is determined at regular intervals and the change in the topography is used to determine an optimum mixture deck topography. During operation, the respective determined topography is compared with the specified optimal batch deck topography, and the optimum amount of placement of the batch for each position is determined and applied. Furthermore, deviations from the development of the batch deck topography can be used to detect problems in the process control of the melting tank at an early stage.The invention further relates to the use of the determination method according to the invention in a method for producing glass for controlling the admixture insert.Thus, locally different melting rates and "vulcan" formation caused by the glass flow of the hot glass and gas formation in the melting process can be avoided and the energy efficiency of the trough can be improved.It is also possible to influence the glass flow and to avoid short-circuit paths in the glass melt by controlling the local thickness of the mixture ceiling, whereby the glass quality can be improved.In addition, the data acquired and processed by the method according to the invention can also be used in combination with artificial intelligence, for example, for detecting anomalies in the melting process. Unusual and thus potentially critical states in the glass melt can thus be detected and early warnings can be given of process-critical situations.List of reference characters100 Cold-top melting trough 110 Electrodes 120 Batch feeder 130 Batch on conveyor belt of the batch feeder 140 Surface of glass melt 150 Batch ceiling 160 Sensor 170 Outlet 180 Glass melt

Claims

Method for acquiring and evaluating data relating to the mixture ceiling and optionally relating to the glass melt and optionally relating to the glass stand in preferably a fully electric cold-top melting tank for melting glass, comprising the following steps: - providing at least one sensor 160 for acquiring point data and one sensor for acquiring area data for non-contact acquisition of data relating to the mixture ceiling 150 at at least the end of the boom 120 of an insertion machine at which mixture is applied to the glass melt, - repeatedly acquiring and storing (a) data relating to the mixture ceiling 150 during the operation of the melting tank 100 using at least the sensor 160, wherein data relating to at least 10 different positions, preferably at least 100 different positions of the mixture ceiling, are acquired, (b) the respective assignment of the data to the position of the end of the boom 120 or of the sensor 160, processing the captured data and creating a topography map, preferably a global topography map and / or preferably an optimum topography of the mixture ceiling 150.Method according to claim 1, wherein at least one sensor 160 is used for capturing point data and the sensor 160 is selected from the group consisting of radar, ultrasound, laser triangulation, laser (time-of-flight, LIDAR) or combinations thereof and / or the obtained point measured values are used directly for creating the topography map.The method of claim 1, wherein a sensor 160 is used for detecting surfaces and the sensor 160 is selected from the group consisting of laser scanner, time-of-flight (LIDAR) camera, line pattern laser triangulation, IR camera, photogrammetry or combinations thereof and / or wherein the obtained surface data is used directly or by merging overlapping partial surface data for creating the topography map.Method according to one of the preceding claims, wherein the data are acquired during the batch insertion process and / or wherein the data are acquired without simultaneous batch insertion.Method according to one of the preceding claims, wherein data relating to the glass state and / or data relating to the glass melt are also recorded and processed.The method according to any one of the preceding claims, wherein one or more sensors are housed in a water- and / or air-cooled housing.Use of a method for determination according to any one of claims 1 to 6 in a method for the production of glass for controlling the admixture.Use according to claim 7, wherein locally smaller and / or larger batch thicknesses are set.Use according to Claim 7 or 8, wherein an optimum topography of the mixture ceiling determined by a method according to one of Claims 1 to 6 is set.

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