Which statement best differentiates saturated steam from superheated steam?

• A. Saturated steam comes directly from the drum; Superheated steam is heated by the super heater
• B. Saturated steam is hotter than superheated
• C. Superheated steam comes from the drum
• D. Both are identical

Answer: (A)

The difference hinges on temperature relative to the boiling point at the given pressure. Saturated steam is at the boiling (saturation) temperature for its pressure and leaves the boiler drum in equilibrium with water. If we want hotter, drier steam for turbines, we pass the saturated steam through a superheater, where heat is added to raise its temperature above the saturation mark. That makes it superheated steam. So the statement that saturated steam comes directly from the drum and superheated steam is heated by the superheater correctly captures this distinction. The other ideas—saturated steam being hotter than superheated, superheated steam coming from the drum, or both being identical—don’t fit the physics of how these steam states are produced.