What is the last heating device before feed water enters the boiler?

What is the last heating device before feed water enters the boiler?

• A. Economizer
• B. Preheater
• C. Superheater
• D. Reheater

Answer: (A)

The thing being tested is how feedwater is heated as it makes its way to the boiler in a steam plant. After the water has already been warmed by any feedwater heaters fed with extracted steam, it reaches the economizer. The economizer sits in the path of the combustion gases and uses their remaining heat to bring the feedwater up to a higher temperature just before it enters the boiler. This final preheating step boosts overall efficiency because the boiler has to do less energy to turn the water into steam. The other devices perform different roles: a preheater would heat water earlier in the path, a superheater heats steam after it leaves the boiler, and a reheater heats steam later in the turbine cycle.

The thing being tested is how feedwater is heated as it makes its way to the boiler in a steam plant. After the water has already been warmed by any feedwater heaters fed with extracted steam, it reaches the economizer. The economizer sits in the path of the combustion gases and uses their remaining heat to bring the feedwater up to a higher temperature just before it enters the boiler. This final preheating step boosts overall efficiency because the boiler has to do less energy to turn the water into steam. The other devices perform different roles: a preheater would heat water earlier in the path, a superheater heats steam after it leaves the boiler, and a reheater heats steam later in the turbine cycle.