Boiler performance terms — identify the correct definition What is the term for the ratio of heat actually used in producing steam to the heat liberated in the furnace (based on fuel fired)?

Introduction / Context:
Several similar-sounding performance metrics exist for boilers. Picking the correct definition is essential for calculations, acceptance tests, and energy audits. Here we focus on distinguishing “boiler efficiency” from “equivalent evaporation” and related terms.

Given Data / Assumptions:

• Fuel energy input measured on a lower or higher heating value basis (as specified).
• Steam generation at stated pressure and quality (dryness fraction or degree of superheat).
• Steady operation during test runs.

Concept / Approach:
boiler efficiency η_b = (useful heat added to water/steam) / (heat released by fuel in the furnace)Equivalent evaporation converts actual steam generation to an equivalent amount “from and at 100°C.” Factor of evaporation is the per-kilogram heat requirement relative to the standard condition. “Power of a boiler” is an older term sometimes linked to boiler horsepower, not an efficiency.

Step-by-Step Solution:

Verification / Alternative check:
Acceptance test codes (e.g., ASME PTC) define efficiency via the heat balance across the boiler boundaries, aligning with this ratio.

Why Other Options Are Wrong:

• Equivalent evaporation: a standardized output measure, not an efficiency.
• Factor of evaporation: a multiplier used to convert actual to equivalent evaporation.
• Power of a boiler / evaporation ratio: different performance descriptors, not the specified ratio.

Common Pitfalls:
Mixing up equivalent evaporation and efficiency; ignoring blowdown losses and radiation when computing Q_useful.

Final Answer: