USCG Exam PracticeBoiler and steam propulsion fundamentals
In a water-tube boiler, what is the purpose of the economizer?
- A. To raise the temperature of steam above its saturation point before it enters the turbine
- B. To warm combustion air using heat recovered from the flue gas
- ✓ To preheat incoming feedwater using residual heat from the flue gasCorrect
- D. To circulate boiler water between the steam drum and the water drum by natural convection
Why C is correct
The economizer is a heat-recovery surface located in the flue gas path that preheats incoming feedwater before it enters the boiler drum. The superheater raises steam temperature above saturation, and the air heater warms combustion air. Natural circulation between drums is accomplished by the generating tubes and downcomers, not the economizer. (NAVEDTRA 14104 §4-1)
Cited:NAVEDTRA 14104 §4-1