Convection Recuperator Maintenance Tips
To properly maintain your recuperator, we recommend periodic visual inspections of the unit at least once a year, and
preferably twice a year. Thermal Transfer can provide a field technician to conduct this recuperator inspection if desired.
The primary areas to closely inspect are the first few rows of tubes on the hot side of the recuperator. These tubes are
almost always the first to fail since they operate at the highest temperatures and are the first tubes exposed to any
abrasives and/or corrosives in the waste gas.
Failure of a few tubes may not dramatically affect overall furnace operation, but as more tubes fail, the performance
of the furnace will deteriorate. The following conditions may indicate a leaking recuperator:
* Lower than normal combustion air flow to the burners
* Lower than normal combustion air preheat temperature
* Lower than normal combustion air pressure downstream of the recuperator
* Higher than normal combustion air pressure drop through the recuperator
* Higher than normal waste gas flow exiting the recuperator
* Lower than normal waste gas temperature exiting the recuperator
* Higher than normal oxygen level in the waste gas exiting the recuperator
Should failed tubes be discovered, an emergency fix to stop the air leaking from these tubes is to cut out and plug the tubes.
Please keep in mind that plugging tubes is only a temporary repair and the recuperator should be removed and properly repaired
by Thermal Transfer in our fabricating facility. Because of the long delivery time required to fabricate a recuperator, we
recommend purchasing replacement tube bundles in advance so they will be on hand when needed.
Other parts of the recuperator to look at during routine maintenance inspections are as follows:
- Check the amount of particulate build-up on the external surfaces of the tubes and on the bottom tube sheet, and remove it if it is excessive.
- Check the condition of all the tubes in the recuperator and plug the failed tubes as required. If many tubes have failed, replace the recuperator with a new unit and have the old unit repaired.
- Check the condition of the upper and lower tube sheets (if visible).
- Check the condition of the castable refractory on the upper and lower tube sheets.
- Check the condition of the combustion air inlet and outlet ducts.
- Check to make sure the recuperator is free to expand in all directions.
- Check the packing in the gaps between the recuperator and the flue, and replace as required.
- Check all components associated with the over-temperature protection system and make sure they are operating properly.
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