Boiler efficiency benchmarking

[nimmer]

I'm looking for some benchmarking data specific to the types of boilers I have. I'd like some guideline on the highest efficiency I can expect. I have 2 Combustion Engineering VU-40, waterwall header, tangentially fired, hung boilers that burn either natural gas or #6 fuel oil built and installed in 1968. The only upgrade that has been made is burner rebuild with Coen low NOx Burners. We generate 560psi superheated steam. Is it reasonable to expect different efficiencies from these boilers? Any help would be greatly appreciated.

 

[sdduck]

Just a short note to remember that the efficiencies will be different for the different fuels. The combustion of natural gas produces much more water than oil, so all other things being equal, the efficiency of natural gas will be lower than oil.