SEFPRO GUARD® Tank monitoring solution: Optimizing furnace maintenance through temperature sensing and corrosion assessment

As higher amounts of electricity are introduced, glass contact refractories in melting tanks undergo significant changes in corrosion behavior. For instance, from 10% boosting onwards, and even more for super boosted and hybrid furnaces, the maximum corrosion will no longer be located at the metal line, but in the middle part (see Figure 1) of sidewall blocks, where glass temperatures and velocities are higher. It is worth noting that this new maximum corrosion zone is critical with regards to current practices used to evaluate blocks remaining thicknesses. Indeed, in most of the cases, the highest corrosion rates on the blocks would be located behind insulation, in non-cooled zones. Therefore, insulation removal might be needed to perform wear measurements. Furthermore, hook measurements, which used to be very helpful, would be more difficult to be executed at significant depth in the glass.

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Operating new furnace technologies is a real challenge for glassmakers considering the very limited experience with regards to different refractory behavior and hence lifetime, new and potentially more numerous critical areas, the evolution of processing conditions, and the maintenance schedule, among other pain points. To support glassmakers on their journey towards decarbonation, SEFPRO GUARD^® Tank monitoring has been designed to track soldier block temperatures on the cold face and assess periodically the corresponding corrosion profile.

SEFPRO GUARD® Tank monitoring system is composed of the following components:

• Thermal sensors with SEFPRO Shield® protection (SEFPRO’s patented material)
• Data acquisition system including data logger and computer
• Web portal with raw data, alerts, and corrosion information

Thermocouples register the temperature profile at the cold face of the block including over “blind”/insulated soldier blocks. They are located at different heights and protected inside a SEFPRO Shield® board, as described below.

Then, these thermocouples are connected through compensation cables to cabinets where electrical signals are converted to temperature.

Finally, the information is transmitted to a computer cabinet by Power-Over-Ethernet (POE) and streamed onto a cloud platform where all post-treatment analyses are conducted: corrosion profile assessment, detection of abnormal event, alerts algorithms, and scorecard calculations. All of these collected data remain confidential and property of the user. 

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The temperature history of each block, as well as the alerting system and corrosion profile assessments, are stored in a secure environment online that are accessed by glassmakers through the SEFPRO GUARD® web portal. Hence, it is possible to follow all monitored furnaces data remotely whilst maintaining a high cybersecurity level. 

In order to correlate temperature evolution and events to furnace management, additional operational data can be collected by the device or directly incorporated through SEFPRO GUARD® web portal. Thanks to machine learning and data analysis algorithms, new indicators can be provided through the portal such as corrosion profile.

Figure 3 shows the web portal landing page that summarizes instrumented blocks positions and their temperature level. Similar views are available to display variation of temperature or remaining block thickness.

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By accessing the SEFPRO GUARD® web portal, multiple visualization options are available to track temperatures, follow alerts, identify events, or evaluate corrosion through this user-friendly digital solution. Information and indicators are accessible throughout the whole furnace campaign, without limitations in terms of refractory material and block thickness.

The temperature measurement solution has been developed to ensure reliable temperature data acquisition over time, from furnace start-up to end of life. To achieve this goal, a patented, ceramic composite material has been developed by SEFPRO to ensure thermal, chemical, and mechanical stability of the temperature sensors: SEFPRO Shield®. 

Throughout the furnace lifetime, and especially during heat-up when mechanical stresses in the furnace structure are at their highest, the sensors remain protected. This protective board is placed between the soldier blocks and the insulation tiles. Thanks to its composite technology, the low thickness of SEFPRO Shield® minimizes the impact on the sidewall thermal conditions and design, as displayed in Figure 2. 

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Then, thermocouples are inserted inside vertical channels within the SEFPRO Shield® boards at optimal positions as shown in Figure 5. This offers the advantage of possible thermocouple replacement in case of damage during the furnace lifetime.

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Last but not least, this temperature measurement solution is compatible with maintenance operations for the melting tank. SEFPRO Shield® is available in both one-piece and modular formats and is adaptable to both full-height and partial patching strategies.

Again, SEFPRO Shield® needs to be considered as part of the insulation structure and managed as such during maintenance operations.
 

Now that reliable temperature profiles on the cold side of the instrumented blocks are available in real time, the acquired data can be exploited in different ways. First, it is possible to analyze the temperature signals block-by-block to alert the furnace operator in case of abnormal events. Specific events or operations can lead to an increase or decrease in temperature at different areas of the furnace. Thanks to SEFPRO GUARD®, several glassmakers have been able to identify and correct abnormalities in their furnace cooling/insulation, improving their energy efficiency.

Using artificial intelligence analyses of the temperature data in real time, it is possible to set up a limit value above which an alert will be activated. As displayed in Figure 6, the abnormal temperature variation will be highlighted on the web portal if an alert is on, and a notification will be sent to the operator.

Then, through combined analysis of the temperature measurements at different positions in the same SEFPRO Shield® or through the various blocks and zones monitored all around the furnace, it is possible to identify the root cause of temperature changes and improve understanding of furnace behavior and its impact on glass contact refractories

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Over the last decades, SEFPRO performed extensive numerical and experimental studies on the mechanisms driving refractory corrosion, considering process conditions and material characteristics. The resulting numerical models were validated with lab trials, pilot tests, and finally at industrial scale.

Based on the glass temperature and velocity profiles close to the soldier block, considering the design and physical properties of the soldier block refractories, and the cold-face temperature data measured by the SEFPRO GUARD® Tank monitoring system, a numerical model is constructed to provide regular estimations of the corrosion profile, which are published onto the SEFPRO GUARD® web portal.

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The periodic estimation of refractory corrosion profiles allows users to monitor critical areas and fine-tune furnace operating conditions based on real-time data. This valuable information helps optimize furnace lifetime, prevent glass leak incidents and maintain glass quality.

Several views are available on the SEFPRO GUARD® Web portal to make full use of the corrosion calculation. Figure 7 displays the corrosion profile as seen on the web portal for each instrumented block. The minimum remaining thickness and the corresponding position are also visible.

It is possible to compare corrosion profiles over time and thus check the impact of furnace aging or changes in processing conditions on the minimum remaining thickness position. This position can shift depending on energy and boosting repartition, for example. It is also possible to compare the calculated profiles with manual measurements or previous campaign history by uploading reported data directly into the web portal.

In Figure 8, an example of a long-term evolution of block thickness over more than 2 years is depicted. The corrosion profile assessment can be carried out regularly. The frequency of this calculation should depend on the type of glass, furnace design, and operation, and the harshness of the monitored zone, among other factors. 

By using this feature, corrosion evolution trends can be analyzed to plan maintenance. As shown in Figure 8, during some specific periods, corrosion kinetics can be faster due to furnace management. This new information allows users to collect insightful data for the optimization of furnace design and operations.
 

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With the trend to use more and more electricity as an energy source for glass melting on the road to decarbonization, SEFPRO is fully committed to developing smart and innovative real-time monitoring systems as a way to provide easy, safe, and reliable methods to manage glass furnace tank aging.

Thanks to machine learning algorithms supported by cloud technology, a friendly and secure web interface, and robust temperature monitoring hardware, SEFPRO GUARD® solution provide glassmakers with the possibility to track the temperature evolution of soldier blocks and correlate it to furnace operations, progressive deterioration, and abnormal events. The periodic assessment of corrosion profile can be used as a strategic decision-making tool for maintenance operations, whether preventive or corrective.

SEFPRO GUARD® Tank Monitoring System offers consistent, valuable information on refractories corrosion, including for “blind”/insulated soldier blocks, to adjust maintenance, prevent glass leaks, and collect insightful data for the optimization of furnace design and operations. This solution should help glassmakers make the best decisions.