🔍 Key Concepts

• Meaning of the term "laning" in relation to gas flow through a boiler tube bank • How uneven gas velocities and flow paths form between tubes • Effect of deposits, blockages, or changes in gas path on heat transfer and tube metal temperature

💭 Think About

• Ask what physical change in the tube bank or gas path would cause flue gases to concentrate in a few narrow paths instead of spreading evenly across all tubes • Consider which option would most likely create obstructions or constrictions that divert gas flow into "lanes" • Think about which conditions mainly affect combustion quality versus those that mainly affect the path of gas flow after combustion

✅ Before You Answer

• Be clear on whether the option affects combustion conditions (pressure, air, flame) or the gas flow path through the tube bank • Visualize a section of tube bank with some tubes partially blocked or insulated on the gas side—how would the gas redistribute? • Verify which listed condition would most directly cause localized high-velocity gas channels between tubes rather than uniformly distributed flow