Estimate boiler efficiency from losses, using fuel, O₂ and stack temperature, find the minimum blowdown from TDS and see what combustion tuning, an economizer and blowdown heat recovery are worth.
Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.
Share of fuel energy (LHV) lost in each item.
LHV-basis efficiency at today’s stack temperature and with an economizer.
Take this page’s results to another calculator with the fields already filled in.
Cash flow of the improvement: investment in year 0 and annual savings escalated at the rate entered, discounted at the MARR.
The report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. In the print dialog, choose Save as PDF.
Use the heat-loss method: from stack O₂ and temperature and the fuel composition, compute dry gas and moisture losses; adding radiation and other losses, efficiency is 100% minus the total (ASME PTC 4).
It depends on fuel and burner. Natural gas usually runs at 2% to 3% O₂; oil 3% to 4%; grate-fired biomass 5% to 8%. Reduce it with a flue gas analyzer while watching CO.
Each lb of blowdown carries saturated water at boiler pressure. At 150 psig with 77 °F make-up, about 290 Btu/lb. At 8% blowdown on a 20,000 lb/h boiler, that is over 460,000 Btu/h lost continuously.
Important notice: Indus Metrics tools produce estimates and pre-sizing results from the data you enter and from published engineering methods. They do not replace design, calculations or reports signed by a licensed professional engineer (PE), nor verification against the applicable codes, standards and regulations, such as OSHA rules and the ASME codes. Material and fuel properties vary: check manufacturer data or your own process analyses before deciding. By using this site you agree to the Terms of Use.
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