🔍 Key Concepts

• Natural circulation in boilers – how hot and cold water move due to density differences • Function and location of risers vs downcomers in a boiler • Purpose of water wall tubes and how they are supplied with water

💭 Think About

• Think about which components carry the relatively cooler, denser water from the steam drum down toward the furnace walls to feed the water wall tubes. • Consider which parts of the boiler carry the hotter, lighter mixture of water and steam upward back to the drum, and whether those are the ones that maintain circulation to the water wall tubes. • Ask yourself: are water wall tubes the destination of circulation flow, or the elements that drive that flow to other parts?

✅ Before You Answer

• Identify which component’s primary job is to bring feedwater from the drum down to the lower headers of the water wall tubes. • Verify which components mainly carry the mixture upward rather than supply the walls from above or below. • Make sure you distinguish between parts that absorb heat (generating tubes, water wall tubes) and parts that primarily transport water to those areas.