Under normal operating conditions, a drop in...

🔍 Key Concepts

• heat transfer in a superheater (how gas temperature and gas velocity affect steam temperature) • difference between steam velocity and gas velocity in relation to time available for heat transfer • what equipment directly changes steam temperature versus what mainly affects other parts of the cycle (economizer, feedwater system)

💭 Think About

• Ask yourself: In an uncontrolled interdeck superheater, what mainly determines how hot the steam gets as it passes through? • Which change would reduce the amount of heat transferred from the hot combustion gases to the steam flowing in the tubes? • Which options affect superheater outlet steam temperature directly, and which mostly influence boiler efficiency or drum conditions instead?

✅ Before You Answer

• For each choice, trace the immediate physical effect on the gas-side and steam-side of the superheater (temperature, velocity, heat transfer area, exposure time). • Eliminate any options that affect overall boiler efficiency but would not specifically cause a quick change in superheater outlet temperature under normal conditions. • Focus on the option where a change would lower gas-to-steam heat transfer right at the superheater, without needing other system changes first.

Under normal operating conditions, a drop in the steam temperature leaving an uncontrolled interdeck superheater could be caused by a __________.

decrease in steam velocity through the superheater

decrease in combustion gas velocity through the superheater

badly fouled economizer

drop in the feedwater temperature

🔍 Key Concepts

💭 Think About

✅ Before You Answer