🔍 Key Concepts

• Function and location of screen tubes in a water-tube boiler • Where the highest radiant heat from the furnace is directed • Relative position of the saturated tube bank, superheater, water drum, and refractory in the gas/heat flow path

💭 Think About

• Which boiler component is directly exposed to the most intense furnace radiation and would benefit most from shielding? • Where are screen tubes placed: before or after the main generating banks and superheater in the gas flow? • Which of the listed parts is most vulnerable to damage from direct radiant heat rather than just hot gases?

✅ Before You Answer

• Confirm what screen tubes are: water-cooled tubes arranged to shield something behind them from radiant furnace heat • Visualize a cross-section of a water-tube boiler and identify what sits immediately behind the screen tubes in the path of radiant heat • Eliminate options that are already water-cooled surfaces or built to withstand direct flame or radiant heat without additional shielding