🔍 Key Concepts

• Natural circulation in water-tube boilers (how water/steam moves without a pump) • Difference between downcomers and risers (where each is located and what flows in them) • Where feedwater actually enters and how it reaches the tubes

💭 Think About

• Picture the path of water and steam in a water-tube boiler: from drum, through tubes, back to drum. Where in this path would downcomers logically be placed? • Ask yourself: in a natural-circulation boiler, what drives the circulation and what role do the heavier/colder and lighter/hotter fluids play? • Which component (downcomer or riser) would you expect to contain mostly cooler, denser water rather than steam/water mixture?

✅ Before You Answer

• Be clear on which parts of the boiler carry rising hot steam/water mixture versus descending cooler water. • Verify whether feedwater distribution is normally done by an internal feed pipe or by downcomers. • Check if the option you choose would logically increase circulation in the water-wall circuits rather than slow it down.