Boiler Heat Balance Sheet — What Does It Show? In a standard boiler heat balance sheet for 1 kg of dry fuel, what information is recorded and balanced?

Introduction / Context:A boiler heat balance sheet itemizes how the energy released by fuel combustion is distributed among useful steam generation and various losses. It is a key tool for diagnosing performance and planning improvements such as better insulation, air preheating, or excess-air control.

Given Data / Assumptions:

• Basis: 1 kg of dry fuel (unless otherwise stated).
• Standard enthalpy references for steam, feedwater, dry flue gas, and moisture.
• Measured flue-gas composition and temperatures to estimate stack loss.

Concept / Approach:The sheet accounts for total heat released and allocates it to: heat in steam (useful), dry flue-gas loss, moisture in fuel, water formed from hydrogen (latent plus sensible), unburnt losses, radiation and unaccounted losses. Moisture and hydrogen content are explicitly included because they impose a significant latent heat penalty as water is evaporated and superheated in the products.

Step-by-Step Solution:Compute total heat input from lower heating value (or higher, as specified).Calculate useful output: enthalpy rise of steam above feedwater conditions.Itemize losses: stack (sensible), latent due to moisture in fuel and water from hydrogen, radiation/unaccounted, unburnt.Ensure balance closure: input equals useful output plus losses.

Verification / Alternative check:Cross-check closure error; a small difference indicates reliable measurements and assumptions.

Why Other Options Are Wrong:Options (a), (b), and (c) are all true features of a heat balance sheet; therefore 'all of the above' is correct.

Common Pitfalls:Ignoring hydrogen-to-water conversion, which can cause substantial latent heat loss under high excess air.Confusing basis (dry vs as-fired) and miscounting moisture contributions.

Final Answer:all of the above