What is the role of a steam drum in a water-tube boiler?

• A. It separates steam from water, provides a reservoir of water for the risers, and houses level and safety devices.
• B. It stores fuel.
• C. It mixes gas and air.
• D. It cools steam.

Answer: (A)

In a water-tube boiler, the steam drum is the place where steam is separated from the water and where the feedwater supply for the risers is stored. It collects saturated steam from the water-packed tubes, removes entrained water to ensure dry steam entering the steam lines, and provides a reservoir of water for the risers and downcomers to maintain a steady, continuous flow to the generating tubes. It also houses important level and safety devices—such as water level indicators and safety valves—to monitor and protect boiler operation. This combination of separating moisture, providing a water reservoir for circulation, and mounting instrumentation and safety components is why this role fits best. Storing fuel, mixing gas and air, or cooling steam aren’t functions of the steam drum.