Lesson 8: Aux. Circ, Water system

Question 1

1. What is the purpose of the Auxiliary Circulating System?

Answer 1

It cools the ACW

Question 2

2. What is the purpose of the heat exchanger?

Answer 2

Transfers heat from the ACW to the Aux. Circ. Water

Question 3

3. Draw a one line diagram showing the flow of the auxiliary circulating system?

Answer 3

Cooling Tower - Aux Circ Pump - Heat Exchangers (YUBAS) - Return to Cooling Tower

Question 4

4. What is the purpose of the air purging system?

Answer 4

It removes air from the system.

Question 5

5. What voltage is the Aux. Circulating pump motor?

Answer 5

4160 Volts

Question 6

6. What should be checked on the motor and pump before starting? After Starting?

Answer 6

Pre-Start:

Breaker racked in
Safe/Run in Run
Discharge Valve closed (air blocked)
Suction Valve open
Oil leaks
Oil Levels
Water Leaks and expansion joint condition
Motor air intakes clear
Bleed air out of pump
Verify instrument air is blocked to discharge valve,
if other pump is running note the discharge pressure.

Post Start:

Outlet Valve open
Heat/Vibration on motor and pump bearings.
Oil levels on motor/pump
Check for leaks and expansion joint		
Slinger Rings
Oil Levels						
Leaks, packing leak off.
Discharge pressure = 35psi
Verify instrument air is open for discharge valve,

Question 7

7. What is the purpose of the amertap system?

Answer 7

It cleans the inside of the tubes in the Condenser and the YUBAs.

Question 8

8. Why should we be concerned about a high differential pressure across the screens on the amertap system?

Answer 8

A high DP indicates that the screens could be full of debris.

Question 9

9. How many balls does the amertap system hold? What size balls does it take?

Answer 9

YUBA – 200, 25 mm balls. Condenser – 700, 27 mm balls.

Question 10

10. Does the Aux. Circulating water flow through the tubes of the heat exchanger or around the tubes?

Answer 10

Aux. Circ. Water runs through the tubes.

Question 11

11. What is the purpose of the anodes and grounding straps on the heat exchanger?

Answer 11

To protect against scale and corrosion build up.

Question 12

12. Describe putting the system in service.

Answer 12

1. Breaker racked in
2. Safe/run in run
3. Suction valve open
4. Discharge valve closed
5. Instrument air blocked if its the first pump, or open to discharge valve if not
6. Put the Discharge valve switch in auto
7. Crack open inlet valve to YUBA heater
8. Open vents on YUBA
9. Aux circ pump checks
10. Cooling tower level is raised to 82 inches
11. Bleed off the air in the pump
12. When you have good flow start the pump and bleed/vent the air out of the YUBA
13. When YUBA has good flow open inlet and outlet valves fully open on YUBA
14. Close YUBA vent

Question 13

13. Why do we use inverted cooling flow?

Answer 13

Inverted flow provides a better transfer of heat.