Over-temperature issue during the operation of a three-bed RTO
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Hello, esteemed colleagues. There is a three-bed RTO that has been in operation for some time now, and its regenerative element is made of MLM plate-type ceramic. The exhaust gas processed by this RTO is a combination of exhaust gases from various painting and drying rooms; its concentration varies considerably depending on the production mode and timing of the preceding processes. There is a strange issue at the moment: the temperature sensor located on top of the air intake heat storage ceramic often triggers over-temperature alarms, with temperatures reaching 50–200°C higher than those in the combustion chamber (the temperature sensors in the combustion chamber are over 1 meter long, and due to their material properties they may bend at high temperatures), with temperatures reaching around 900 degrees. Based on the PLC screenshots sent from the site, this situation occurs whether the high-temperature bypass is not activated or when it is set to 100%. The on-site technicians tried running this RTO with no load after shutting it down (without introducing VOCs exhaust gas, only air), but the problem persisted. My guess is that there is combustible material accumulating inside the heat-storing ceramic; as air is introduced and the temperature rises gradually, this causes the oxides accumulated on the ceramic to oxidize and release heat. However, I’ve only been in this field for a short time, so I’m not sure if this idea is correct Those who are experienced with regenerative oxidation furnaces, please share your thoughts!
This is a common occurrence; it happens when the intake concentration is high. Sometimes, the temperature in the middle of the heat storage material also exceeds the limit. As for why it is the upper or middle part of the heat storage material, it is estimated to be related to the type of organic substance, that is, to its ignition point
After shutting down the system, I tried running this RTO with no load (without introducing VOCs exhaust gas, only air), but the problem persisted. Let’s confirm whether energy can be conserved
My guess is that the combustible gas storage element gradually heats up, and when it reaches the upper part of the ceramic storage material, a reaction occurs in advance, releasing heat. At that time, an experienced colleague in the industry suggested removing one or two layers of ceramic from the storage chamber, and this issue should have been resolved as a result
Running with an empty vehicle? Have you turned on the gas at this time? The explanation is not clear. How can there be an increase in temperature without heat?
When running without a load, the burner needs to be turned on to supply heat and raise the temperature; otherwise, air is simply introduced, and it’s pointless for the equipment to remain at room temperature
Coked up? What is the specific temperature distribution like? Is it the one I built?
At that time, only the temperature of the upper layer of ceramic was too high, while the temperature of the lower layer was normal. In which province is the location of the project you are working on?