Using a boiler economizer primarily increases which aspect of boiler performance?

Using a boiler economizer primarily increases which aspect of boiler performance?

• A. It preheats exhaust gas to boost flame temperature.
• B. It reduces emissions by catalytic conversion.
• C. It increases water chemical purity.
• D. It increases overall boiler efficiency.

Answer: (D)

An economizer recovers heat from the hot exhaust and uses it to preheat the incoming feedwater. Because the feedwater starts at a higher temperature, less fuel energy is required to raise it to the boiling and steam-separation temperature. In other words, the energy you put in to produce the same amount of steam decreases, so the boiler’s efficiency improves. This is the primary performance gain of an economizer. It doesn’t preheat exhaust gas, it doesn’t catalytically reduce emissions, and it doesn’t affect water purity, so those options don’t describe its main effect.

An economizer recovers heat from the hot exhaust and uses it to preheat the incoming feedwater. Because the feedwater starts at a higher temperature, less fuel energy is required to raise it to the boiling and steam-separation temperature. In other words, the energy you put in to produce the same amount of steam decreases, so the boiler’s efficiency improves. This is the primary performance gain of an economizer.

It doesn’t preheat exhaust gas, it doesn’t catalytically reduce emissions, and it doesn’t affect water purity, so those options don’t describe its main effect.