🔍 Key Concepts

• Soot deposits act as insulation on heat transfer surfaces • Relationship between heat transfer, gas temperature, and metal temperature in boiler tubes • How combustion efficiency and stack temperature indicate boiler performance

💭 Think About

• If a thick soot layer is on the outside of generating tubes, does more or less heat get into the water/steam inside those tubes? What happens to the temperature of the gases leaving the furnace? • Think about what soot on generating tubes (not in the superheater) directly affects: water/steam heating, gas path temperatures, or combustion process? • For each choice, ask: would this be a direct result of dirty tube surfaces, or is it more related to firing conditions, burner setup, or steam flow characteristics?

✅ Before You Answer

• Identify whether soot insulation makes heat transfer to the water/steam better or worse • Decide whether poorer heat transfer tends to make exhaust/stack gas temperature higher or lower for the same firing rate • Check which options are effects specifically tied to generating tube surface condition, not superheater design or burner adjustment