Boiler Efficiency Calculator

Calculate boiler thermal efficiency from steam output, fuel consumption, and calorific value.

kg/hr
kcal/kg
From steam tables at operating pressure
kcal/kg
Water temperature × 1.0 (approx.)
kg/hr
kcal/kg
Rice husk ≈ 3000, Coal ≈ 5500, Diesel ≈ 10500, Furnace oil ≈ 9800
Formula
(steamOutput * (enthalpySteam - enthalpyFeedwater)) / (fuelConsumption * calorificValue) * 100
steamOutput Steam Generated (kg/hr)
enthalpySteam Enthalpy of Steam (kcal/kg)
enthalpyFeedwater Enthalpy of Feed Water (kcal/kg)
fuelConsumption Fuel Consumption (kg/hr)
calorificValue Gross Calorific Value of Fuel (kcal/kg)
Worked Example
1
Given:
calorificValue = 8000
enthalpyFeedwater = 60
enthalpySteam = 660
fuelConsumption = 160
steamOutput = 2000
2
Apply the formula:
(steamOutput * (enthalpySteam - enthalpyFeedwater)) / (fuelConsumption * calorificValue) * 100
3
Result:75 %

What is Boiler Efficiency?

Boiler efficiency is the ratio of useful heat output (in the form of steam) to the total heat input from fuel. It indicates how effectively the boiler converts fuel energy into steam energy.

Boiler Efficiency (%) = [Steam Output × (H_steam − H_feedwater)] ÷ [Fuel × Calorific Value] × 100

Typical Boiler Efficiencies

Boiler TypeEfficiency
Water tube boiler80–88%
Fire tube boiler75–85%
Fluidized bed80–90%
Biomass boiler70–78%

Common Fuels in Dairy Plants

FuelCalorific Value (kcal/kg)
Rice husk2800–3200
Groundnut shell3500–4000
Bagasse2300–2500
Coal5000–6000
Furnace oil9700–10000
LDO/Diesel10000–10500
LPG11900
Natural gas~8500 kcal/m³

How to Improve Boiler Efficiency

  1. Reduce excess air: Control combustion air for complete burning
  2. Recover waste heat: Install economizer and air preheater
  3. Maintain steam traps: Replace faulty traps immediately
  4. Insulate steam lines: Reduce radiation losses
  5. Treat feed water: Prevent scaling and corrosion
  6. Regular blowdown: Remove dissolved solids from boiler drum