Blowdown Rate & Feedwater

The blowdown needed to hold the boiler TDS limit, the feedwater flow, and the heat going down the drain.

Unit system

Inputs

Steam production

Boiler water TDS limit (ppm)

The limit given by the boiler maker. Typically 3000–3500 ppm on low-pressure shell boilers.Makeup water TDS (ppm)

Condensate return fraction

Returned condensate carries no salt; it dilutes the feedwater TDS and lowers the blowdown needed.Boiler pressure (absolute)

Makeup water temperature

Blowdown flow

274kg/h

Blowdown as a fraction of steam

0.0274

Feedwater flow	10,274 kg/h
Feedwater TDS (ppm)	80
Makeup water required	4,110 kg/h
Heat leaving with the blowdown	53.26 kW
Verdict	Low blowdown — good

Steam is taken to carry no solids. With foaming or carryover the real blowdown need is higher.
This is continuous blowdown. Bottom (sludge) blowdown is separate and intermittent, and is not included.

A PDF carrying the inputs, results, assumptions and the source. A one-time code is sent to your address.

Results are for engineering pre-assessment and are not a product selection commitment. Final responsibility rests with the user.