Question 32 QMED04 - Boiler Technician-Watertender

The Correct Answer is C **Why Option C is Correct:** The primary function of the steam drum (or upper drum) in a D-Type marine boiler is to separate the steam generated in the water tubes from the water/steam mixture. Water is fed into this drum, and the boiling process occurs in the tubes connected below. The resulting mixture of steam and water rises back into the steam drum. Inside the drum, various internal fittings (such as cyclone separators, scrubbers, and baffles) are used to efficiently remove the remaining water droplets (moisture) from the steam before the steam exits the drum and proceeds to the superheater or main steam line. This ensures that only high-quality, dry steam is delivered for use. **Why Other Options Are Incorrect:** * **A) maintains circulation by forcing steam bubbles downward in the generating tubes:** This is incorrect. Natural circulation in a boiler relies on density differences, with the lighter steam/water mixture rising upward in the heated riser tubes, and the heavier, colder water flowing downward in the unheated downcomer tubes. The steam drum is where the upward flow terminates and separation occurs; it does not force steam bubbles downward to maintain circulation. * **B) acts as a receptacle for heavy suspended solids in boiler feedwater:** This is incorrect. While the mud drum (or lower water drum) often acts as a collection point for sludge and heavy solids that settle out of the water circuit, the steam drum is primarily focused on separating steam from water. While some solids are present in the water circulated through the steam drum, the mud drum is specifically designed for the collection and blowdown of heavier sludge. * **D) supports the superheater tube bank:** This is incorrect. The steam drum receives saturated steam *before* it enters the superheater. The superheater bank is usually supported by separate structural members within the boiler casing or furnace, or sometimes by headers that are structurally independent of the main drums. The steam drum's function is chemical and thermodynamic (separation), not structural support for the superheater.