Priming is the term for water droplets carried with steam leaving a boiler. Which option describes this phenomenon?

• A. Priming
• B. Condensation
• C. Dry steam
• D. Flash steam

Answer: (A)

Priming is the phenomenon where water droplets are carried with steam leaving a boiler. This happens when the steam contains entrained liquid because the separation between steam and water isn’t perfect, often due to high moisture content, rapid load changes, foaming, or inadequate steam-drum separation. The droplets ride along with the vapor as it exits the boiler, leading to wet steam downstream, which can reduce efficiency and cause issues in turbines and piping. This isn’t condensation (which is vapor turning into liquid as it cools), nor is it dry steam (steam with little to no moisture), nor flash steam (water that rapidly becomes steam when pressure drops). So the process described is priming.