Purdom Generating Station

OPERATING PROCEDURE

CIRCULATING WATER SYSTEM
UNIT 8

Purdom Generating StationCirculating Water System

August 1 2014Operating Procedure Unit 8

TABLE OF CONTENTS

SectionPage

1.0Introduction

1.1Purpose and Scope

1.2System Identification and Scope Definition

2.0SYSTEM STARTUP

2.1Preoperational Procedures

2.1.1Prerequisites

2.1.2Prestart Requirements

2.2Precautions and Limitations

2.3Circulating Water System Block Flow Diagram

2.3.1Circulating Water System Startup

2.4Startup of the Circulating Water Pumps

3.0SYSTEM NORMAL OPERATION

3.1System Routine Checks

3.2Rotating the Circulating Water Pumps

4.0SYSTEM ABNORMAL OPERATION

4.1Operating with One Circulating Water Pump

5.0SYSTEM SHUTDOWN

5.1Circulating Water System Shutdown

5.2System Post-Shutdown Checklist

5.2.1Short Term

5.2.2Long Term

6.0ALARM RESPONSES

6.1Summary of Alarms

Alarm: Waterbox A/B Inlet Temp High

Alarm: Waterbox A/B Outlet Temp High

Alarm: Cooling Tower Basin Level High

Alarm: Cooling Tower Basin Level Low

Alarm: Circulating Water Pump Motor Overtemperature

7.0CHECKLISTS AND TABLES

Table 1 - Power Supply Checklist

Table 2 - Prestart Valve Lineup Checklist

Table 3 - Local Indicating Instruments

Table 4 - Control Room Indicating Instruments

8.0REFERENCES

8.1P&ID

8.2Electrical One Line Diagrams

8.3Control Diagrams

8.4Instrument Loop Diagrams

8.5Instruction Manuals

8.6Miscellaneous

DraftPage 1

A.B. Hopkins Generating StationCirculating Water System

August 1 2014Operating Procedure Unit 2 HPA

1.0Introduction

1.1Purpose and Scope

The purpose of this operating procedure is to provide the operator with specific procedures for operating the Circulating Water System. The operating procedures include those detailed procedures required to start-up, operate, and shutdown the Circulating Water System in a logical, efficient, and safe manner. The Circulating Water System supplies the necessary cooling water to condense LP turbine exhaust steam in the condenser. The operating procedure includes the following sections:

Section 2.0 - System Startup

Section 3.0 - Normal Operations

Section 4.0 - System Abnormal Operations

Section 5.0 - System Shutdown

Section 6.0 - Alarm responses

Section 7.0 - Checklists and Tables

1.2System Identification and Scope Definition

The circulating water system is a closed loop system that begins at the cooling tower, flows through the condenser and ends at the cooling tower. Branch connections supply the condensate cooling heat exchangers, steam turbine lube oil coolers and condenser vacuum pump heat exchangers from the supply header upstream of the condenser and discharge to the cooling tower return header. Each of the system major components is powered from the 4KV switchgear and 480 V MCCs located throughout the plant.

2.0SYSTEM STARTUP

2.1Preoperational Procedures

2.1.1Prerequisites

  1. The 480 VAC electrical distribution system is in service.
  2. The 4160 VAC electrical distribution system is in service.
  3. The plant air system is in service.

2.1.2Prestart Requirements

  1. All clearances are released and the equipment is in safe operating condition.
  1. The power supply lineup is correct per Table 1.
  2. The prestart valve lineup is correct per Table 2.
  3. All system instrumentation is available per Table 3.

2.2Precautions and Limitations

THE FOLLOWING PRECAUTIONS ARE SYSTEM SPECIFIC OPERATIONAL CONSIDERATIONS THAT MUST BE CLOSELY FOLLOWED. FAILURE TO FOLLOW THESE PRECAUTIONS MAY RESULT IN PERSONNEL INJURY OR EQUIPMENT DAMAGE.

  1. All pumps must be properly vented for proper operation and efficiency.
  1. All oil level bulb/indicators (on motors and reduction gears) are filled to the proper operating level (50 to 75% full).
  2. Adequate protective clothing should always be worn when handling chemicals distributed by this system:

Rubber gloves

Safety glasses

Full face shield

Rubber suit or apron

  1. The respective eye wash and emergency shower stations should be in service and accessible.
  2. If chemicals in this system come in contact with the skin:

Immediately flush the exposed area with water for at least 15 minutes.

Obtain medical attention as soon as possible.

  1. Circulating water pump motors are limited in frequency of starts as follows:

Initial condition - motor cold (at ambient temperature): Up to two starts in succession may be attempted. The motor must be allowed to come to rest before attempting the second start. After the second start, the motor must be allowed to cool for 30 minutes if running, or 60 minutes if not running before a third start may be attempted.

2.3Circulating Water System Block Flow Diagram

2.3.1Circulating Water System Startup

2.4Startup of the Circulating Water Pumps

ACTION / LOC / VERIFICATION
NOTE:The LOC column in this procedure specifies where the associated ACTION step is taken. A "C" step is performed in the Control Room, an "L" step is performed locally, and an "L/P" step is performed at a local panel. A "C/L" or "L/C" step indicates a combination of Control Room and local activities.
NOTE:It is assumed for the purposes of this procedure that both circulating water pumps will be started and that pump 2A will be started first. Pump 2B can be started first. If this is done, substitute 2B for 2A and vice versa in the steps below.
1.VERIFYall condenser doors are closed. / L
2.CLOSEthe condenser waterbox drains. / L
3.OPEN the inlet and outlet waterboxes vent valves. / L
4.VERIFY the condenser waterbox inlet valves are open two turns. / L / Valve position indicator on the valve stem shows valve partially open.
5.VERIFY the condenser waterbox outlet valves are open. / L / Valve position indicator on the valve stem shows valve 100% open.
6.VERIFY the inlet valves to the turbine lube oil coolers, vacuum pump coolers, and condensate cooling water heat exchangers are closed. / L
7.VERIFY cooling tower basin is at operating level. / L/C / Water level in basin is between +74" and +79" on level indicator (2CWLIB064) and the level is maintained by the well water system.
8.VERIFY the cooling tower fan blades are clean and free of any debris or obstructions. / L
9.OPEN the 2A circulating water pump air eliminators. / L
10.VERIFY the oil level in the 2A circulating water pump motor. / L / Oil level in sight glass is between the minimum and maximum marks.
11.CLOSE the rupture disk isolation valve on the 2A circulating water pump discharge. / L
12.VERIFY the main breakers for the 2A and 2B circulating water pump motors are closed and ready for service. / L
13.START the 2A circulating water pump. / C / Red ON indicating light is illuminated in the control room.
Motor current spikes and then returns to normal.
14.CLOSE the 2A circulating water pump air eliminator valve. / L / Air is expelled and pump is primed.
15.CLOSE the waterbox vent valves when water is issued. / L / Air is expelled and waterboxes are primed.
16.SLOWLY OPEN the inlet valves to the turbine lube oil coolers and vent valves. / L / Air is expelled and coolers are primed.
17. CLOSE the turbine oil coolers vent valves when water is issued. / L
18.OPEN the inlet valves to the condensate cooling water heat exchangers and vent valves. / L / Air is expelled and heat exchanger are primed.
19.CLOSE the turbine lube oil coolers vent valves. / L
20.VERIFY water flow is cascading down through the cooling towers. / L
21.VERIFY cirulating water flow through the condenser. / C / Chart recorder in control room indicates flow through condenser is approximately 60,000 gpm.
Note:A minimum of two circulating water pumps must be in operation to ensure adequate flow in the circulating water system preventing any settling of debris in the piping and condenser waterboxes.
22.OPEN the 2B circulating water pump air eliminators. / L
23. VERIFY the oil level in the 2B circulating water pump motor. / L / Oil level sight glass is between the minimum and maximum marks.
24. START the 2A circulating water pump. / C / Red ON indicating light is illuminated in the control room.
Motor current spikes and then returns to normal.
25.CLOSE the 2A circulating water pump air eliminator valve. / L / Air is expelled and pump is primed.
26.VERIFY circulating water flow through the condenser. / C / Chart recorder in control room indicates flow through condenser is approximately 120,000 gpm.
27.OPEN the rupture disk isolation valve on the 2A circulating pump discharge. / L
28.PLACE cooling tower fans in service as needed to maintain proper circulating water temperature. / C / Condenser backpressure is approximately 3" Hg absolute.
Condenser inlet water temperature is approximately 86°F.
29.Notify lab that the circulating water system is in service.

3.0SYSTEM NORMAL OPERATION

3.1System Routine Checks

ACTION / LOC / VERIFICATION
NOTE:The LOC column in this procedure specifies where the associated ACTION step is taken. A "C" step is performed in the Control Room, an "L" step is performed locally, and an "L/P" step is performed at a local panel. A "C/L" or "L/C" step indicates a combination of Control Room and local activities.
NOTE:Proper operation of plant equipment will lead to increased availability, sustained performance, and extended life of the equipment, while reducing the chance of failure. Proper operations include close adherence to operating procedures when starting the equipment, proper monitoring and inspections when the equipment is in normal operation, and following proper operating procedures when shutting down.
1.CHECK all indication listed in Table 3, Local Indicating Instruments. / L / Verify each is within the normal operating range.
2.CHECK all control room indications. / C / Verify all are operating normally.
3.CHECK the circulating water pumps to ensure proper operation. / L / Check discharge pressures.
Check the lubrication level in the motors.
Check for signs of leakage.
Check motor/pump coupling.
Check for abnormal noises or vibration.
4.CHECK the cooling tower fans to ensure proper operation. / L / Check the lubrication level in the gear reducers.
Check for abnormal noises or vibration.
5.INSPECT the cooling tower water distribution fill for signs of algae, slime, and other buildups. / L / The tower fill is clean.
A uniform spray cone is evident at each nozzle.
No scale, algae, slime, or other micro-organisms are visible.

3.2Rotating the Circulating Water Pumps

ACTION / LOC / VERIFICATION
NOTE:The LOC column in this procedure specifies where the associated ACTION step is taken. A "C" step is performed in the Control Room, an "L" step is performed locally, and an "L/P" step is performed at a local panel. A "C/L" or "L/C" step indicates a combination of Control Room and local activities.
NOTE:The Circulating Water pumps are rotated periodically to equalize pump/motor run time. This procedure places pump B in service and removes pump A from service.
1.VERIFY OPENCirculating Water pump B suction valve, WC001B. / L / Butterfly Valve fully open.
2.VERIFY oil level is adequate to motor bearings. / L
4.OPEN the Circulating Water pump B discharge valve 1 turn, WC003B. / L / Butterfly Valve cracked open
6.STARTCirculating Water pump B locally or at the DCS. / L/C / Red ON indicating light is illuminated both in the control room and locally. Pump energizes and discharge pressure increases on pressure indicator WCPI204B
7.SLOWLY OPENCirculating Water pump B discharge valve until fully open. / L / Butterfly Valve fully open
8.STOPCirculating Water pump A locally or at the DCS. / C/L / Green OFF indicating light is illuminated both in the control room and locally.
9.PLACECirculating Water pump A in standby. / L

4.0SYSTEM ABNORMAL OPERATION

4.1Operating with One Circulating WaterPump

ACTION / LOC / VERIFICATION
NOTE:The LOC column in this procedure specifies where the associated ACTION step is taken. A "C" step is performed in the Control Room, an "L" step is performed locally, and an "L/P" step is performed at a local panel. A "C/L" or "L/C" step indicates a combination of Control Room and local activities.
NOTE:Proper operation of plant equipment will lead to increased availability, sustained performance, and extended life of the equipment, while reducing the chance of failure. Proper operations include close adherence to operating procedures when starting the equipment, proper monitoring and inspections when the equipment is in normal operations, and following proper operating procedures when shutting down.
NOTE:Plant load is limited to the condensing ability of the circulating water system. Therefore, if only one circulating water pump is available the plant load will be limited by the ambient conditions.
1.VERIFY both circulating water pumps are not available for service. / L/C
2.VERIFY the operating circulating water pump is operating properly. / L/C / Discharge pressure and flow are within single pump limits.
Motor load has not exceeded 184 amps.
3.REDUCE steam turbine load as required to maintain the proper backpressure. / C / Backpressure remains between 1-3" Hg absolute.
4.PLACE cooling tower fans in service as needed to maintain the proper circulating water temperature. / C / Condenser backpressure is approximately 3" Hg absolute.
Condenser inlet water temperature is approximately 86°F.

5.0SYSTEM SHUTDOWN

5.1Circulating Water System Shutdown

ACTION / LOC / VERIFICATION
NOTE:The LOC column in this procedure specifies where the associated ACTION step is taken. A "C" step is performed in the Control Room, an "L" step is performed locally, and an "L/P" step is performed at a local panel. A "C/L" or "L/C" step indicates a combination of Control Room and local activities.
NOTE:The Circulating Water System is typically one of the last systems to be secured during unit shutdown. With the exception of maintenance, the system should be maintained in a filled and vented condition.
1.VERIFY Unit No. 2 steam turbine is shut down.
2.VERIFY all steam drains to the main condensers are isolated.
3.VERIFY OPEN the condenser vacuum breaker. / C/L / Condenser vacuum reading atmospheric pressure.
4.VERIFY Unit No. 2 Condensate Cooling Water System is shut down. / C / Condensate cooling water pumps are off.
5.VERIFY Unit No. 2 Turbine Lube Oil System is shut down. / C / Turbine lube oil pumps are off.
6. STOP the cooling tower fans. / C / Green OFF indicating lights illuminate in the control room.
7.STOP the circulating water pump(s). / C/L / Green OFF indicating lights illuminate in the control room.
Pump motor ammeters read 0 amps.
8.NOTIFY the lab that the Circulating Water System is out of service.

5.2System Post-Shutdown Checklist

When not required for operation, the Circulating Water System must be maintained in a layup condition to preserve its integrity and to prevent internal deterioration and contamination of the piping an components. The type of layup required is determined by the time period the system is estimated to be out of service. If it is estimated that the unit will be out of service for less than three months, a short term layup is performed. If three or more months are anticipated, a long term layup is required.

5.2.1Short Term

A short term layup maintains the Circulating Water System in a state of readiness during an outage. During a short term layup, water is continuously recirculated from the basin through the condenser and out to the cooling tower. During the layup, the cooling tower should be inspected for proper water spray patterns.

5.2.2Long Term

When the circulating water system is to be taken out of service for a long period of time, the circulating water pumps should be shut down and breakers racked out of service. The makeup water system should be taken out of service and the system drained.

Once the long term shutdown is completed and the integrity of the circulating water system is re-established the system may be placed in service following the steps in Section 2 of this procedure.

6.0ALARM RESPONSES

6.1Summary of Alarms

ALARM CONDITIONS
Alarms / Initiating Device(s) / Device Setpoint(s)
Waterbox A Inlet Temp High / TE-1232 / 115°F
Waterbox B Inlet Temp High / TE-1234 / 115°F
Waterbox A Outlet Temp High / TE-1233 / 135°F
Waterbox A Outlet Temp High / TE-1231 / 135°F
Cooling Tower Basin Level High Alarm / LSH-658 / +80"
Cooling Tower Basin Level Low Alarm / LSL-658 / +74"
Motor Overtemperature / Micromax / 155°F

Alarm: Waterbox A/B Inlet Temp High

Initiating Device(s): 2CW -TE-1232/4

Setpoint(s): 115°F

Possible Causes

  1. Improper cooling tower operation
  2. High/low ambient air temperature
  3. High wet bulb temperature
  4. Improper number of cooling tower fans in operation
  5. High makeup water temperature
  6. Initiating device malfunction

Consequences

  1. Possible increase in turbine backpressure due to high circulating water temperature

Immediate Operator Action

  1. Check condenser water inlet temperatures.
  2. Adjust the number of cooling tower fans in operation to maintain proper circulating water inlet temperatures.

Follow Up Operator Action

  1. Verify proper cooling tower fan(s) operation.
  2. Verify temperature drops after additional fan(s) are added.
  3. Verify backpressure is stabilized after temperature is corrected.
  4. Inform Maintenance Department to check/repair/calibrate thermocouple if necessary.

Alarm: Waterbox A/B Outlet Temp High

Initiating Device(s): 2CW -TE-1233/1

Setpoint(s): 135°F

Possible Causes

  1. Improper cooling tower operation
  2. High/low ambient air temperature
  3. High wet bulb temperature
  4. Improper number of cooling tower fans in operation
  5. Initiating device malfunction

Consequences

  1. Possible increase in turbine backpressure due to high circulating water temperature
  2. Possible high turbine

Immediate Operator Action

  1. Check condenser water inlet temperatures.
  2. Adjust the number of cooling tower fans in operation to maintain proper circulating water outlet temperatures.

Follow Up Operator Action

  1. Verify proper cooling tower fan(s) operation.
  2. Verify temperature drops after additional fan(s) are added.
  3. Verify backpressure is stabilized after temperature is corrected.
  4. Inform Maintenance Department to check/repair/calibrate thermocouple if necessary.

Alarm: Cooling Tower Basin Level High

Initiating Device(s): 2CW -LSH-658

Setpoint(s): +80"

Possible Causes

  1. Improper cooling tower makeup water valve position
  2. Improper operation of cooling tower blowdown valves
  3. Initiating device malfunction

Consequences

  1. Possible cooling tower basin overflow

Immediate Operator Action

  1. Dispatch operator to cooling tower basin.
  2. Check cooling tower basin level.
  3. Open cooling tower blowdown valve.
  4. Check well water pump status.
  5. Verify makeup valve is closed.

Follow Up Operator Action

  1. Monitor cooling tower water basin level.
  2. Verify level drops after blowdown valves are opened.
  3. Inform Maintenance Department to check/repair/calibrate level switch if necessary.

Alarm: Cooling Tower Basin Level Low

Initiating Device(s): 2CW -LSL-658

Setpoint(s): +74"

Possible Causes

  1. Loss of well water pump
  2. Piping rupture
  3. Initiating device malfunction

Consequences