Boiler Circulating Pumps

Question 1

1. Why does the drum level need to be high before starting the first BCP?

Answer 1

In order to fill the water wall tubes of the boiler, and maintain a water level in the drum.

Question 2

2. Why is it so important to have a purge on a BCP before shutting it down?

Answer 2

It’s to prevent iron oxides from getting into the motor windings, and to maintain flow for cooling of the motor cavity.

Question 3

3. What does the down comer to pump casing metal temperature have to be before starting a BCP?

Answer 3

Within 100 degrees

Question 4

4. What are the Alarm and trip points on the BCP differential pressure?

Answer 4

Alarm- 20 psid

Trip- 13 psid

Question 5

5. What steps need to be taken before starting a BCP that has been isolated?

Answer 5

Have plant operator ensure that pumps are filled and vented, and purge set at 3-5 gpm, cooling water valved in, and proper valve alignment on BCP’s. Ensure pump casing temperature is within 100 deg of down comer temperature

Question 6

6. At what motor cavity temperature will the suction valve trip closed?

Answer 6

149 degrees