The term residual fires refer to what condition?

The term "residual fires" specifically refers to the presence of fire on burner tips after a shutdown. This condition indicates that although the main combustion process has been halted, flames may still be present where fuel can accumulate, particularly at the tips of burners. The flames represent a potential hazard as they can lead to incomplete combustion or the resurgence of unwanted fire situations. Understanding residual fires is crucial for ensuring safe operations and emergency response in facilities handling combustion processes.

While options discussing steam presence in a boiler, continued combustion after shutdown, and excessive smoke in the stack touch on related concepts, they do not accurately capture the definition of "residual fires." Steam presence indicates boiler function rather than fire status, continued combustion implies that operations are still active, and excessive smoke would suggest improper combustion rather than the specific scenario of flames lingering on burner tips.