Blowdown

Definition

The controlled discharge of concentrated boiler water, replaced by fresher feedwater, used to keep dissolved solids within safe limits. It controls cycles of concentration.

Blowdown keeps TDS and alkalinity in the range where bubble behavior stays predictable and foam cannot form, but it carries away already-heated water that must be replaced and reheated. Operating well below limits wastes water, fuel, and chemistry because lower cycles mean more blowdown and more cold makeup, so the target is the highest safe concentration, not the lowest. The sensible heat carried out with blowdown is a quantifiable fuel penalty.

Related concepts

Blowdown Fuel Penalty · Dispersion · Conductivity Controller

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Part of The Blueprint of Water · 🛠️ operations