Fired Heater Learning Center

Supplemental Firing Calculator

Supplemental Firing Calculator

This calculator determines the flue gas composition resulting from the combustion of a fuel gas with a given flue gas. Additionally it calculates the lower heating value of the fuel gas and the flue gas flow after combustion.

Flue Gas Composition, mole% Fuel Composition, mole %
N2 = CH4 = C6H14 = C2H4 =
O2 = C2H6 = CO = C3H6 =
CO2 = C3H8 = H2 = N-C4H8 =
H2O = N-C4H10 = N2 = C6H6 =
Ar = I-C4H10 = CO2 = H2O =
SO2 = N-C5H12 = C = O2 =
CO = I-C5H12 = S = H2S =
Flue Gas Flow, lbs/hr =
Flue Gas Temp, °F =
Firing Temp, °F =


The formulas and correlations presented herein are all in the public domain and are to be used only as a learning tool. Note that any product, process, or technology in this document may be the subject of other intellectual property rights reserved by sponsors or contributors to this site. This publication is provided as is, without any warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of fitness for a particular purpose, or non-infringement.

The formulas, correlations, and methods presented herein should not be considered as being recommended by or used by the sponsors of this site. The purpose of this site is educational and the methods may or may not be suitable for actual design of equipment. Only a fired heater design engineer is qualified to decide if a calculation or procedure is correct for an application.