Question 305Steam Plants - Assistant Engineer

The correct answer is B) dull red flame with black streaks. Insufficient combustion air supply will cause an atomizer flame to appear as a dull red flame with black streaks. This is because the lack of oxygen in the combustion process results in incomplete combustion, leading to the formation of soot particles that appear as black streaks within the flame. The other answer choices are incorrect because: A) A ragged flame is more indicative of a clogged or malfunctioning atomizer, not necessarily insufficient combustion air. C) A pointed flame is more characteristic of a well-functioning atomizer with proper air supply. D) A light yellow flame with white streaks would indicate an excess of combustion air, not a lack of it.