Which fuel property directly influences sulfur oxide emissions?

• A. Moisture content only.
• B. Sulfur content.
• C. Volatile matter only.
• D. Grindability.

Answer: (B)

Sulfur content in the fuel is the property that directly controls sulfur oxide emissions. When fuel burns, the sulfur present oxidizes to sulfur oxides (primarily sulfur dioxide, with some sulfur trioxide in hotter zones). The amount of sulfur oxide that can form is essentially tied to how much sulfur is in the fuel, so higher sulfur content means higher potential SOx emissions (barring removal by scrubbers or other processes). Other fuel properties influence how the fuel burns or how much other pollutants are formed, but they don’t set the baseline amount of sulfur oxides that can be produced. Moisture content can affect flame temperature and efficiency; volatile matter affects ignition and burn rate; grindability affects how finely the fuel is ground and how it burns. None of these change the inherent quantity of sulfur available to form sulfur oxides.