Ask A Scientist© Engineering Archive

Index Key:   ENG049
Author:      jeff d gilbertson
Subject:     Fuel oil/Fuel gas burn temperatures.
We have two different types of burners on our boilers.  Natural gas and fuel
oil.  Our information indicates that the natural gas flame burns at about
3000 degrees.  We have no information about the fuel oil temperature.  The
natural gas has a btu content of 1027 btu/cf.  The fuel oil has a btu
content of 18,100 btu/lb.  Could you tell me at what temperature the oil
fire would burn?  In case it is necessary, we use Babcock & Wilcox return
flow oil burner and ring type gas burners.  Their capacities are 5,660
lbs/hr oil and 1,600 cfm gas.

Response #:  1 of 1
Author:      david r munoz
This is a complicated question and can probably best be answered by measure-
ment.  You can calculate the adiabatic flame temperature for any fuel air
oxidation reaction (fancy terminology for combustion).  Adiabatic means
without heat transfer (losses).  Therefore, if you had a perfectly insulated
chamber and you had a combustion process occurring and you measured the
flame temperature, you would be measuring the adiabatic flame temperature. 
However, in real burner applications, there is always heat transfer and this
is the complicating factor.  Either you estimate the heat transfer loss and
include it on the balance of energy equation that is used to find the flame
temperature or you measure the flame temperature.  Looking in one of my
references, I see that I cannot readily find a value for the adiabatic flame
temperature of fuel oil.  However, I would say that your 
3000 degrees F is probably a good estimate (+ or - 100 F).