Boiler heat-balance closure calculator

All heat inputs and outputs must close on a consistent enthalpy basis.

Units

q_{\text{fuel}} = q_{\text{steam}} + q_{\text{blowdown}} + q_{\text{flue}} + q_{\text{surface}} - q_{\text{air}} - q_{\text{feed}} - q_{\text{cond}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

q_{\text{fuel}} = 9{,}000{,}000 + 400{,}000 + 1{,}600{,}000 + 200{,}000 - 100{,}000 - 500{,}000 - 600{,}000 = 10{,}000{,}000

Symbol	Meaning	Unit
$q_{\text{fuel}}$	fuel input	Btu/h
$q_{\text{steam}}$	outgoing steam enthalpy	Btu/h
$q_{\text{blowdown}}$	blowdown enthalpy loss	Btu/h
$q_{\text{flue}}$	flue-gas energy	Btu/h
$q_{\text{surface}}$	boiler and flue surface losses	Btu/h
$q_{\text{air}}$	incoming air enthalpy	Btu/h
$q_{\text{feed}}$	makeup feedwater enthalpy	Btu/h
$q_{\text{cond}}$	return condensate enthalpy	Btu/h

Symbol	Meaning	Unit
$q_{\text{fuel}}$	fuel input	kW
$q_{\text{steam}}$	outgoing steam enthalpy	kW
$q_{\text{blowdown}}$	blowdown enthalpy loss	kW
$q_{\text{flue}}$	flue-gas energy	kW
$q_{\text{surface}}$	boiler and flue surface losses	kW
$q_{\text{air}}$	incoming air enthalpy	kW
$q_{\text{feed}}$	makeup feedwater enthalpy	kW
$q_{\text{cond}}$	return condensate enthalpy	kW

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.