🔍 Key Concepts

• Combustion efficiency in boilers and what flue-gas analysis tells you • Typical CO₂ percentage range in flue gas for efficient fuel-oil combustion • Relationship between excess air and CO₂ concentration in flue gases

💭 Think About

• If combustion is close to ideal, what happens to CO₂ levels in the flue gas—are they relatively high, low, or zero? • How does increasing excess air (more air than chemically needed) affect the percentage of CO₂ in the flue gas? • Which of the choices directly relates to flue-gas composition, and which are more about deposits or fuel properties?

✅ Before You Answer

• Compare the 12–14% CO₂ range with what you’d expect for efficient combustion of fuel oil in marine boilers • Ask whether excess air generally raises or lowers the CO₂ percentage in the flue gas sample • Separate effects of fuel properties/deposits (vanadium, carbon deposits) from effects on measured gas composition (CO₂, O₂)