TL;DR

Regenerator packing blockage reduces combustion air preheat temperature and increases fuel consumption. Monitor the air preheat trend and schedule a regenerator clean-out before blockage reaches 30% of packing volume.

What you might see

regenerator checker packing temperature drop below design
combustion air preheat temperature declining
gas pressure drop across the regenerator increasing
NOx emission rising from reduced combustion air temperature

Likely causes

Tap to mark as ruled out

Batch carryover depositing alkali and batch materials on the packing bricks
Sulfate condensation on the cooler upper courses of the packing from temperature drop
Packing brick crumbling from thermal cycling and partially blocking the gas passages
Reduced reversal frequency allowing one-sided packing buildup

Required tools

Combustion air temperature logger
Gas differential pressure gauge
Confined-space entry equipment
Replacement checker bricks
LOTO kit

Safety first

Regenerator chambers are confined spaces with extreme residual heat. Full confined-space entry procedure is required.
Furnace gases contain CO and SO2. Personal gas monitor mandatory during any regenerator access.

Procedure

7 steps · ~90 min

1
Track the combustion air temperature at the regenerator exit over time. A declining trend at constant pull rate confirms packing blockage.[1]
2
Measure the gas pressure drop across the regenerator at each reversal. Increasing differential confirms reduced free area in the packing.[1]
3
Schedule a regenerator clean-out during the next available furnace stop.
4
During the stop, allow the regenerator to cool to below 100 degC before entry.
Warning: Regenerator chambers retain extreme heat for many hours after a furnace stop. Verify the internal temperature with a thermocouple before any person enters. Confined-space entry permit is required.
5
Remove loose blockage and broken packing brick from the affected courses. Inspect the remaining packing brick for crumbling or cracking.
6
Replace degraded packing courses with new checker bricks of the correct profile.
7
After the restart, verify the air preheat temperature returns to the design value within the expected warm-up period.

Sources

Sorg Sorg LoNOx Melter Glass Tank Furnace general technical documentation, Sorg
General glass furnace regenerator maintenance and packing inspection procedures (general)

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