Which statement best describes ultimate analysis of coal?

• A. It measures moisture only.
• B. It predicts the ash fusion temperature.
• C. It analyzes proximate properties like moisture and ash.
• D. It yields elemental composition (carbon, hydrogen, sulfur, nitrogen, and oxygen) used to predict combustion products and emissions.

Answer: (D)

Ultimate analysis focuses on the elemental makeup of coal, providing the amounts of carbon, hydrogen, sulfur, nitrogen, and oxygen. This elemental information is what you use to predict what forms during combustion and what emissions may result, because the elements determine the stoichiometry of the reactions and the potential pollutants (like CO2 from carbon, SOx from sulfur, NOx from nitrogen, and water from hydrogen). This is why it’s the best description: it directly ties the fuel’s chemical composition to combustion products and emissions.

Other analyses measure different properties: moisture alone is just one part of proximate analysis, ash fusion temperature relates to ash behavior and melting characteristics, and proximate analysis covers moisture, volatile matter, fixed carbon, and ash rather than the elemental composition.