🔍 Key Concepts

• Identify whether the boiler is fire-tube (Scotch) or water-tube by looking at where the gases are in relation to the tubes. • Determine how many drums there are and how they are arranged (in-line, stacked, or offset to form a shape such as a "D"). • Note the number of furnaces (burners) and the direction of firing (down-fired vs horizontally-fired), and where the superheater and economizer are located in the gas path.

💭 Think About

• From the illustration, is the flame going through large shells with tubes inside (fire-tube), or is water inside banks of small tubes exposed to furnace gases (water-tube)? • Do the upper and lower drums and the furnace/water wall arrangement visually form any recognizable layout (such as a single furnace alongside a bank of generating tubes)? • Trace the gas flow: furnace → superheater → generating bank → economizer. How does that sequence match the descriptions in the choices?

✅ Before You Answer

• Verify whether you see one or two main drums, and if there is a single furnace or multiple furnaces. • Confirm if the boiler has water walls and downcomers (water-filled tubes lining the furnace and vertical tubes leading from drum to drum). • Check whether the construction resembles a large cylindrical shell (Scotch type) or a drum-and-tube framework (water-tube type) before eliminating answers.