Tube fouling on a WHRS boiler is rarely uniform. Where the deposits accumulate — leading rows, lower banks, around supports, near gas-flow discontinuities — tells you whether the cause is heavy dust, sticky chemistry, gas distribution problems, or simply normal wear of the boiler's self-cleaning provisions. Heat transfer falls in step with the deposit thickness, and the rate of decline accelerates because dust insulates the tube surface from the gas it was meant to absorb heat from. The fouling pattern is the diagnostic; the cleaning frequency is the consequence.
Why this matters in the whrs
Tube fouling is the single most common reason WHRS boilers underperform their generation targets. The cost is direct — every fouled tube is a tube not transferring heat at design rate — and the recovery is rarely linear, because dust that has consolidated into a hard deposit cannot be removed with the same online cleaning that handles soft accumulation.
The upstream cause matters more than the deposit itself. Heavy dust loading from the kiln, sticky chemistry from AFR ash, or temperature profiles that condense volatiles on the tubes in the wrong location each call for a different long-term fix. Plants that treat fouling as an upstream signal, not just a boiler issue, usually preserve generation across the campaign.