In a boiler feedwater system, hot water is located immediately downstream of which component?

• A. Softener
• B. Deaerator
• C. Boiler
• D. Economizer

Answer: (A)

The key idea here is that hardness removal happens first in a boiler feedwater setup. Water is treated to remove calcium and magnesium in a softener before it is heated and deaerated. Because the subsequent steps heat and condition the water for use in the boiler, the feedwater that has just left the softener is effectively the first “hot” feedwater in the sequence. This softened water then goes on to the deaerator (where dissolved gases are removed and further heating occurs) and finally to the boiler and its exchangers. Keeping hardness out of the heated sections prevents scale buildup and protects heat transfer surfaces, so placing the softener upstream makes the downstream hot water proper feedwater for the rest of the process. The other components (deaerator, economizer, boiler) perform heating, gas removal, or steam generation, but the initial hot feedwater is defined right after the softener.