Question 256Steam Plants - Assistant Engineer

The correct answer is A) increase the fuel oil control valve opening. When the steam pressure drops below a set value on an automatically fired auxiliary boiler with rotary cup atomizers, the combustion control system will increase the fuel oil control valve opening. This is because the decrease in steam pressure indicates a drop in boiler output, so the control system needs to increase the fuel supply to the boiler to maintain the desired steam pressure. The other options are incorrect because: B) increasing the rotary cup speed would be an unnecessary step, C) decreasing the back pressure regulating valve opening would restrict the steam flow instead of increasing it, and D) decreasing the supply steam control valve opening would also restrict the steam flow, which is the opposite of what is required to maintain the steam pressure.