AUX STEAM/BOILERS

Question 1

What are the trip conditions for the Aux Boiler?

Answer 1

High Steam Pressure (218#), Low Drum Level (-7”), B/U Low Level (-8.5”), Loss of FD fans (open breaker), Min Air Flow Switch (MAFS), Low atomizing steam pressure (15#), Low Fuel Oil Pressure (125#), Loss of Flame (fire eye).

Question 2

What is the normal pressure control range for the Aux Boiler?

Answer 2

185-200#.

Question 3

At what pressure does the 1st relief valve lift, the boiler trip, and the 2nd relief valve lift?

Answer 3

1st relief valve lifts at 215#, boiler trips at 218#, and 2nd relief valve lifts at 220#.

Question 4

When does AS-V-1A/B (Aux Steam Supply to 8th Stage Heater) close?

Answer 4

It closes if the supply header pressure is <175# or the heater shell pressure is >50#.

Question 5

What happens if a single FO pump trips?

Answer 5

It trips the boiler due to perturbations.

Question 6

What is the direct source of feedwater (FW) for CO-T-1A?

Answer 6

CO-T-1A is the direct source of FW, while CO-T-1B is the backup via CO-V-111A/B, which is normally CLOSED for FLEX.

Question 7

What is the impact of losing the 1A 4kV bus?

Answer 7

Both oilers are unavailable due to FO-P-1A/B being out of service.

Question 8

What is the impact of losing the 1C 4kV bus?

Answer 8

AS-B-1B becomes unavailable (powered by 1K 480V).

Question 9

Why is feedwater heated to 200°F?

Answer 9

To remove iron and improve hydrazine oxygen scavenging.

Question 10

What is the function of FO-V-31A/B?

Answer 10

They receive AUTO trip signals to cut off boiler fuel supply.

Question 11

How is fuel atomizing provided?

Answer 11

By Service Air when steam drum pressure is <100#, and by atomizing steam otherwise.

Question 12

What is the purpose of pegging steam?

Answer 12

To maintain the boiler warm for freeze protection and quick starts, supplied from the 8th Stage EX header.