Question 309Steam Plants - Assistant Engineer

The correct answer is C) carbon deposits on the furnace walls. Throttling the burner air register of a lit burner can result in incomplete combustion, leading to the formation of carbon deposits on the furnace walls. When the air supply to the burner is restricted, it reduces the amount of oxygen available for complete combustion, causing the fuel to only partially burn. This incomplete combustion produces soot and carbon particles that can accumulate on the furnace walls. The other options are incorrect because: A) excess combustion temperature is more likely to occur with too much air supply, not too little; B) carbon deposits on the register doors are not a direct consequence of throttling the air register; and D) too much excess air would not cause carbon deposits, but rather, it would result in more efficient combustion.