Purpose and insight from a furnace heat balance A complete heat balance on an industrial furnace provides which of the following outcomes?

Introduction / Context:
A furnace heat balance systematically accounts for all energy inputs and outputs: fuel chemical energy, sensible air preheat, wall radiation, stack losses, heat to the load, and unmeasured leakages. This accounting is central to performance improvement and troubleshooting in high-temperature operations.

Given Data / Assumptions:

• Measured or estimated temperatures and flow rates for fuel, air, flue gas, and load.
• Known fuel composition and lower heating value.
• Steady operation during the test period.

Concept / Approach:
By quantifying each heat sink and source, the engineer can compute overall thermal efficiency (useful heat to load / fuel heat input), identify the largest loss mechanisms (e.g., stack sensible heat, wall losses, openings), and evaluate improvement potential by modeling changes such as installing recuperators, sealing leaks, or optimizing firing patterns.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check stack loss estimates via flue-gas temperature and excess oxygen; compare wall losses against surface temperature and emissivity correlations.

Why Other Options Are Wrong:

• Only thermal efficiency: Heat balance reveals far more than a single KPI.
• Only sources of losses or only scope to reduce: The balance provides both diagnosis and improvement quantification.
• Adiabatic flame temperature only: That is a combustion property, not an output of a plant heat balance on an operating furnace.

Common Pitfalls:
Ignoring air infiltration; neglecting radiation from openings; using higher heating value while measurements reflect lower heating value conditions.

Final Answer:
All of (a), (b) and (c)