Boiler efficiency after fuel conversion
Boiler efficiency after fuel conversion
(OP)
Hi,
I would like to know if there is any effective improve (or not) in a boiler efficiency after a conversion from fueloil to natural gas.
Thanks
I would like to know if there is any effective improve (or not) in a boiler efficiency after a conversion from fueloil to natural gas.
Thanks





RE: Boiler efficiency after fuel conversion
RE: Boiler efficiency after fuel conversion
But, looking only to boiler efficiency and not the overall system, the improvement is related to the energy loss in the flue gas?? Because of the excess air reduction??
But how much is the improvement? Is there any know values or any way to determine it through calculations?
Thanks
RE: Boiler efficiency after fuel conversion
Excess air will play a factor in efficiency as will fuel chemistry and water production.
RE: Boiler efficiency after fuel conversion
The recommendation to read B&W Steam or if you can get a copy of Combustion Engineering's equivalent was a good one.
rmw
RE: Boiler efficiency after fuel conversion
If you are also going to change the pressure part configuration to better deal with the changes heat transfer and corrosion characteristics, then you can increase the boiler efficiency- natural gas boiler may be permited to have a lower stack gas temperature than a fuel oil fired unit, but may require changes to the economizer and air heater to realize that improvement. The fuel gas flame is less radiant and a lower temperature flame than that of fuel oil, so the furnace water wall heat absorption will drop and the heat available for superheating steam increases. The back end velocitywill increase and ther may be tube vibration issues.
RE: Boiler efficiency after fuel conversion
I didn't understand why the efficiency will decrease with HHV and increase with LHV...
Anyway, i've looked in STEAM a i didn't find a value...i will keep looking for it...
Thanks
RE: Boiler efficiency after fuel conversion
Are you just looking for standard efficiency of a NG boiler vs. oil?
RE: Boiler efficiency after fuel conversion
RE: Boiler efficiency after fuel conversion
The HHV efficiency will be reduced due to the higher value of the "water vapor loss" term- natural gas will gnerator a lot more water vapor in the exhaust gas than fuel oil .
LHV efficiency ( and LHV fuel heating values) deducts the heat of vaporization of the generated steam vapors from the heating value of the fuel , so there is no significant water loss term in the efficiency calculation. As I recall , there have been a few published values of LHV efficiencies greater than 100% in the case of a condensing exhaust.