WHRS gas-side pressure drop above the design band is the boiler restricting the gas path the kiln circuit depends on. The cause may be tube blockage from accumulated dust, damaged or deformed tube banks, or simply more dust than the boiler's self-cleaning provisions can handle. The cost is felt twice — once at the WHRS itself in lost heat recovery, and once at the kiln ID fan, which now has to push gas through a path that is tighter than the original system design assumed.
Why this matters in the whrs
Pressure drop on the gas side is the most direct signal of how clean — or how dirty — the boiler is. A trend upward means more dust is sitting on heat-transfer surfaces, less heat is being transferred, and the fan is paying for the difference. Both the steam-generation KPI and the kiln-side energy KPI shift unfavourably, often slowly enough that neither alone triggers attention.
Mechanical consequences accumulate too. Tubes operating with sustained high external loading see fatigue patterns that the design did not anticipate, and the next planned tube inspection becomes the moment when bypass downtime gets pulled into the schedule. Treating ΔP as a leading indicator — not just an alarm — gives the team the cleaning or repair window it needs.