Gaseous fuels — Among the following industrial and by-product gases, which has the lowest calorific value (heating value)?

Introduction:
Designing burners, waste-heat recovery, and fuel-mix strategies requires a clear understanding of the calorific values of industrial gases. Blast furnace gas, converter gas, refinery gas, gobar gas, and coke oven gas differ widely in composition and heating value.

Given Data / Assumptions:

• Comparison is qualitative (lowest heating value).
• Typical industrial compositions are assumed.
• Lower heating value trends are sufficient to rank choices.

Concept / Approach:
Heating value depends on combustible components (CO, H₂, CH₄, higher hydrocarbons). Gas streams heavily diluted with CO₂ and N₂ have low calorific value. Blast furnace gas is notably dilute: high in CO₂ and N₂ with modest CO, giving a very low calorific value compared to biogas or refinery by-product gases that contain substantial CH₄ and higher hydrocarbons.

Step-by-Step Solution:
Identify gas compositions: BF gas is CO-lean and CO₂/N₂-rich → low CV.Compare to refinery gas/coke oven gas: rich in hydrocarbons → high CV.Gobar gas (CH₄ + CO₂) has moderate CV, still far above BF gas.Converter gas has low-to-moderate CV but typically exceeds BF gas.

Verification / Alternative check:
Typical LHV ranges: blast furnace gas ~ 700–900 kcal/m³ (very low), converter gas ~ few thousand kcal/m³, gobar gas ~ 4500–6000 kcal/m³, refinery gas and coke oven gas ~ 9000–12000+ kcal/m³.

Why Other Options Are Wrong:

• Gobar gas: contains significant methane → much higher than BF gas.
• Refinery gas: rich in hydrocarbons → high CV.
• Converter gas: higher than BF gas though still low.
• Coke oven gas: very high due to H₂, CH₄, and light hydrocarbons.

Common Pitfalls:
Assuming all by-product gases are similar; overlooking dilution by inert gases.

Final Answer:
Blast furnace gas