What impact will efficiencies have on boiler performance?

Combustion Efficiency

Combustion efficiency is the effectiveness of the burner only and relates to its ability to completely burn the fuel. The boiler has little bearing on combustion efficiency. A well-designed burner will operate with as little as 15% to 20% excess air, while converting all combustibles in the fuel to thermal energy.

Thermal Efficiency

Thermal efficiency is the effectiveness of the heat transfer in a boiler. It does not take into account boiler radiation and convection losses - for example, from the boiler shell, water column piping, etc.

Fuel-to-Steam Efficiency

The term "boiler efficiency" is often substituted for combustion or thermal efficiency. True boiler efficiency is the measure of fuel-to-steam efficiency. ZOZEN guaranteed boiler efficiencies are fuel-to-steam efficiencies. Fuel-to-steam efficiency is calculated using either of two methods, as prescribed by the ASME Power Test Code, PTC 4.1. The first method is input-output, which is the ratio of BTU output divided by BTU input x 100. The second method is heat balance, which considers stack temperature and losses, excess air levels, and radiation and convection losses. Therefore, the heat balance calculation for fuel-to-steam efficiency is 100 minus the total percent stack loss and minus the percent radiation and convection losses. Fuel-to-steam efficiency is important, but that efficiency calculation does not take into account cycling and purge losses, operating levels, and other variables.

In-Service Efficiency

Fuel-to-steam efficiency is important, but that efficiency calculation does not take into account cycling and purge losses, operating levels, and other variables. More importantly, in-service efficiency—the amount of fuel you have to use to get the needed output, may be a truer measurement of the value of your system. We supply the highest in-service efficiencies on the market. Whether modular, a single boiler, or a hybrid, our cutting-edge designs combined with advanced controls provide the absolute lowest operating cost available.