🔍 Key Concepts

• Boiler heat transfer and how furnaces cool down after shutdown • Effect of air flow through the furnace on metal parts and refractory (brickwork) • Relationship between air/combustion, steam generation, and boiler water level when the burner is secured

💭 Think About

• After you secure (shut down) a boiler burner, what continues to happen inside the furnace and boiler just from stored heat? • What does leaving burner registers open do to the rate of cooling and the temperature stresses on metal and refractory? • Which options describe something that actually happens after fuel and burner are secured, vs. something that requires active firing?

✅ Before You Answer

• Verify what happens to steam generation once fuel is cut off but the boiler and furnace are still very hot. • Consider how rapid cooling versus slow, controlled cooling affects furnace refractory and boiler metal parts. • Distinguish between actions that prevent damage to furnace structure and those that would increase cooling speed.