In the Deaerating Feed Tank (DFT), the auxiliary exhaust steam directly contacts which of the following?

In the Deaerating Feed Tank (DFT), the auxiliary exhaust steam directly contacts which of the following?

• A. Condensate
• B. Boiler water
• C. Feedwater
• D. Lube oil

Answer: (A)

The key idea is that the auxiliary exhaust steam is used to heat and deaerate water by direct contact in the Deaerating Feed Tank. It directly contacts the condensate returning from the condenser. As the steam enters the tank, it condenses on the condensate, transferring heat and driving off dissolved gases—primarily oxygen—so the condensate becomes deaerated before it’s mixed with makeup water to form feedwater for the boiler. Lube oil and the boiler water itself aren’t the water being heated in this direct-contact setup, and the purpose isn’t to deaerate those.

The key idea is that the auxiliary exhaust steam is used to heat and deaerate water by direct contact in the Deaerating Feed Tank. It directly contacts the condensate returning from the condenser. As the steam enters the tank, it condenses on the condensate, transferring heat and driving off dissolved gases—primarily oxygen—so the condensate becomes deaerated before it’s mixed with makeup water to form feedwater for the boiler. Lube oil and the boiler water itself aren’t the water being heated in this direct-contact setup, and the purpose isn’t to deaerate those.