Boiler Blowdown Rate Calculator
Use measured steam flow and paired feedwater/boiler-water TDS to estimate concentration cycles and continuous blowdown.
A QUICK WALKTHROUGH
How to use this tool
- Enter steam mass flow and feedwater and boiler-water TDS using the same concentration unit.
- Optionally enter boiler blowdown and feedwater temperatures to estimate sensible heat carried out.
- Review the mass-balance estimate and compare it with your treatment program and operating measurements.
Mass-balance method
At steady state, with negligible solids in steam and no other water losses: cycles of concentration = boiler-water TDS ÷ feedwater TDS; blowdown mass flow = steam mass flow ÷ (cycles − 1); feed flow = steam + blowdown. Blowdown fraction is blowdown ÷ feed flow.
Optional sensible-heat estimate
When both temperatures are entered, sensible heat rate is approximated as blowdown × 4.186 kJ/(kg·K) × (blowdown temperature − feedwater temperature). This liquid-water estimate does not model pressure, flashing, steam quality, or heat recovery.
Treatment settings matter
TDS limits and cycles are boiler-, pressure-, and treatment-specific. Follow the water-treatment provider, boiler manufacturer, and applicable operating requirements; this calculator does not set a safe TDS target. Source: U.S. DOE, Guidelines for Estimating Unmetered Industrial Water Use, Steam Heating System Example: https://www.energy.gov/node/757381 . The optional 4.186 kJ/(kg·K) liquid-water approximation is a rounded near-ambient value; NIST Chemistry WebBook water thermochemistry data: https://webbook.nist.gov/cgi/cbook.cgi?ID=C7732185&Mask=2&Units=CAL .
GOOD TO KNOW
Common questions
Does this choose the boiler-water TDS target?
No. Use the target established for your boiler and water-treatment program.
What if the TDS values use different units?
Convert them to the same concentration unit before calculating.
Are inputs uploaded?
No. The calculation runs in this browser.