🔍 Key Concepts

• Function of water wall tubes in a boiler furnace • Direction of flow in downcomers vs. risers • Which tubes are primarily for heat absorption vs. circulation supply paths

💭 Think About

• Think about which tubes carry water downward from the steam drum to supply other tube circuits, and which carry the heated mixture back up • Ask yourself: are the water wall tubes part of the downward flow or the upward heated flow? • Which of the listed tubes is mainly there to feed other tubes rather than to generate steam directly?

✅ Before You Answer

• Be clear on the normal circulation loop: steam drum → downcomers → lower headers → water wall/generating tubes → risers → steam drum • Verify which tubes are usually unheated or lightly heated and used to deliver relatively cooler water • Check which option is typically located at the bottom/side of the boiler to distribute water to the furnace walls