Boiler & Steam Water Treatment Consulting

Boiler reliability starts before the boiler, at feedwater purity. Dissolved oxygen, hardness, silica, and total dissolved solids in feedwater set the ceiling on how clean the internal chemistry can ever be — no dosing programme compensates for a demineraliser or deaerator that isn't performing. We review deaerator vent rate and terminal temperature difference, condensate polisher performance, and make-up demineralisation train condition (ion exchange or RO/EDI) against the actual feedwater quality the boiler receives, because a marginal deaerator or a leaking condenser tube introducing raw cooling water or oxygen is one of the most common root causes of "unexplained" boiler tube failures.

Cycle chemistry regime selection is the next decision: all-volatile treatment (AVT) using ammonia and hydrazine or an oxygen-scavenger alternative for high- purity, once-through and drum boilers; phosphate treatment (coordinated or congruent phosphate) for drum boilers with some hardness ingress tolerance; caustic treatment where a controlled free-hydroxide alkalinity is used to buffer against acidic contamination. Each regime has a distinct failure mode if misapplied. Phosphate hideout — where sodium phosphate solubility drops sharply at high temperature and phosphate disappears from solution at load, only to reappear as pH swings on load reduction — is a classic phosphate-regime pitfall. Caustic gouging occurs when free caustic concentrates under deposits or in crevices at high heat flux, locally dissolving the protective magnetite layer and attacking base metal — a risk that rises sharply wherever under-deposit corrosion mechanisms are already active from hardness or iron fouling.

Oxygen control matters at every stage: dissolved oxygen ingress via deaerator malfunction, condenser leaks, or pump seals drives pitting corrosion in feedwater lines and economisers, so oxygen scavenger dosing (sulphite, hydrazine, or volatile alternatives) is verified against actual residual, not just injection rate. Steam purity is the other side of the ledger: mechanical carryover (droplets) and vaporous carryover (silica volatilisation at high pressure) both deposit contaminants downstream — on superheater tubes, turbine blades, or process equipment — so we assess steam drum internals, silica-to-alkalinity ratios, and blowdown rate together rather than treating carryover as a single-cause problem. Finally, condensate return quality is often the weakest link: contamination from process leaks, corrosion product pickup in condensate piping, and inconsistent polishing all feed straight back into the boiler, undermining an otherwise well-run chemistry programme.