START-UP FROM A COLD CONDITION

This section describes the recommended procedure for starting the HRSG from a cold condition with no pressure in the HP, IP and LP boiler sections. Proceed as follows:

1. Purge the HRSG in accordance with NFPA 85, Chapter 8.9.2 (Combustion Turbine Exhaust Systems) guidelines.

It is understood that purging is accomplished by using air at ambient temperatures.

The ambient air temperatures during a normal purge cycle will not have any damaging effect on any of the HRSG components.

2. Align all HRSG valves as shown under the column labeled “START FROM COLD”

on Tables 1 through 6.

NOTE: Some of the following procedures are redundant to what is shown on Tables 1 through 6. This is done to emphasize the

ALSTOM Power Revision: 0 5-5 4. The HP Desuperheater Spray Water Control Valve (TV-301) is in ‘AUTO’. The HP

Desuperheater Spraywater Control Valve Isolation Valves (V-313 and V-317) shall remain open. The HP Desuperheater Spraywater Power Block Valve (HV-300) is in

‘AUTO’.

5. The RH Desuperheater Spray Water Control Valve (TV-701) is in ‘AUTO’. The RH Desuperheater Spraywater Control Valve Isolation Valves (V-713 and V-717) shall remain open. The RH Desuperheater Spraywater Power Block Valve (HV-700) is in

‘AUTO’.

NOTE: Although desuperheating is not required except at peak turbine load, it is good practice to have the control station available whenever the unit is operating.

6. The following Drain Valves are in AUTO:

HP Superheater 1 Drain Valve (HV-284), HP Superheater 2 Drain Valve (HV-282), HP Superheater 3 Drain Valve (HV-280),

Allow any condensate in these sections to drain.

7. The following Drain Valves are in AUTO:

Reheater 1 Drain Valve (HV-765), Reheater 2 Drain Valve (HV-760), IP Superheater Drain Valve (HV-580)

Allow any condensate in these sections to drain.

8. The LP Steam Outlet Drain Valves (HV-948 and HV-949) are in AUTO. Allow any condensate to drain.

9. Prior to start up, reset the water level set points in the feedwater control system to ensure that the water levels in the HP, IP, and LP Drums and Deaerator Storage Tank are just above the Cold Start-up NWL (see Tables 7 through 10). Use the HP Evaporator (HV-180), IP Evaporator (HV-480) and LP Evaporator (HV-825) Intermittent Blow-off Valves as necessary to reduce water levels.

10. Open the HP Feedwater Stop Valve (HV-102), IP Feedwater Stop Valve (HV-400) and LP Feedwater Stop Valve (HV-800).

11. Place the Condensate Preheater in bypass by closing the Condensate Preheater Feedwater Stop Valve (HV-002) and opening the Condensate Preheater Bypass Stop Valve (HV-003). Set the Preheater Recirculation Pump (PMP-040) and Control to OFF.

12. Close the HP Main Steam Outlet Stop Valve (HV-001), open the HP Steam Startup Vent (HV-342). Engage the HP to RH Bypass Valve (not in ALSTOM Power scope) to control the HP Steam Outlet Pressure to 58.99 barg (60.00 bara).

13. Open the IP Main Steam Outlet Stop Valve 604), IP Steam Startup Vent (HV-600), and the RH Steam Outlet Startup Vent (FV-780). Close the HRH Stop Valve (not in ALSTOM Power scope) and the HRH to Condenser Bypass (not in ALSTOM Power scope).

14. Close the LP Main Steam Outlet Stop Valve (HV-919) and open the LP Steam Startup Vent (FV-915).

NOTE: When starting the second gas turbine/HRSG train, with the first train already operating, the HP Main Steam Outlet Stop Valve (HV-001), and the LP Main Steam Outlet Stop Valve (HV-919) shall remain closed until the pressure is within 5% and temperature is within 28°C of downstream piping. After permissives clear and stop valves open, the NRV in the respective lines will open once the pressures match and will then begin admitting steam.

15. If needed, restart feedwater pumps and ensure that pumps are running and all feed system valves are lined up. (See ‘START FROM COLD’ on Tables 1 through 6.) 16. Allow gas turbine exhaust flow to the HRSG by starting the gas turbine.

17. While the steam generator is being brought up to pressure, all cold steam piping should be gradually heated and drained of condensate. The HP Startup Vent Valve 342), RH Steam Outlet Startup Vent Valve (FV-780), IP Startup Vent Valve (HV-600), and the LP Startup Vent Valve (FV-915) must stay opened to insure a positive flow of steam which will reduce thermal expansion.

To warm the piping downstream of ALSTOM Power scope, open the bypass valve on the HP Main Steam Outlet Stop Valve (HV-001A), the bypass valve on the LP Main Steam Outlet Stop Valve (HV-919A). Next, open a drain or vent downstream of ALSTOM Power scope to allow the steam from the bypass valve to warm the piping.

Ensure that all steam piping downstream of the boiler piping is drained prior to admitting steam.

NOTE: When starting the second gas turbine/HRSG train with the first train already operational, the bypass valves on the Main Steam Outlet Stop Valves are used to warm piping.

18. Once the LP steam lines have been properly warmed, the LP steam section is “on line” with steam ready to be introduced to the Deaerator. Open the LP Main Steam Stop Valve (HV-919) and close the bypass (HV-919A). The LP Startup Vent Valve (FV-915) will modulate open / closed in order to maintain the LP Steam Outlet Pressure (PIT-915A and PIT-915B) at 4.19 barg (5.20 bara).

19. Warm the Pegging Steam Lines and drain the lines of any condensate by opening the following valves:

Low Range LP Pegging Steam Drain Valve (HV-072D).

High Range LP Pegging Steam Drain Valve (HV-004D).

IP Pegging Steam Drain Valve (HV-008D).

Close the Drain Valves after a period of at least 5 minutes.

NOTE: When starting the second gas turbine/HRSG train with the first train already operational, the Pegging Steam Lines will not require warming.

For Startup on Natural Gas Operation:

ALSTOM Power Revision: 0 5-7 When the Low Range Pegging Steam Control Valve (PV-002D) has reached 100%

open and the Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) falls below 0.99 barg (2.00 bara), this indicates that the required pegging steam is more than the available steam from the Low Range LP Pegging Steam Control Valve (PV-002D). Switch over control of the pegging steam flow to the High Range LP Pegging Steam Control Valve (PV-001D). Completely close the Low Range LP Pegging Steam Control Valve (PV-002D). Modulate open / closed the High Range LP Pegging Steam Control Valve (PV-001D) to maintain Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) at 0.99 barg (2.00 bara). The High Range LP Pegging Steam Line will automatically be drained of condensate for 5 minutes using the High Range LP Pegging Steam Drain Valve (HV-004D) prior to opening the High Range LP Pegging Steam Control Valve (PV-001D) if the line has been out of service for at least one (1) hour.

When the required pegging steam is more than the available LP steam, the IP Pegging Steam Control Valve (PV-003D) is to be enabled and modulated open / closed in conjunction with High Range LP Pegging Steam Control Valve (PV-001D) to maintain Deaerator set pressure. The IP Pegging Steam Line will automatically be drained of condensate for 5 minutes using the IP Pegging Steam Drain Valve (HV-008D) prior to opening the IP Pegging Steam Control Valve (PV-003D) if the line has been out of service for at least one (1) hour.

NOTE: The IP Pegging Steam Control Valve (PV-003D) is being used to maintain the Deaerator Storage Tank pressure at 0.99 barg (2.0 bara) once the High Range LP Pegging Steam Control Valve (PV-001D) has reached 70% of the fully open position.

During startup, control setpoint for Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) will be set at 0.99 barg (2.00 bara).

For Startup on Solar Fuel (Oil) Operation:

21. Modulate open / closed the Low Range Pegging Steam Control Valve (PV-002D) to maintain Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) at 3.49 barg (4.50 bara).

When the Low Range Pegging Steam Control Valve (PV-002D) has reached 100%

open and the Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) falls below 3.49 barg (4.50 bara), this indicates that the required pegging steam is more than the available steam from the Low Range LP Pegging Steam Control Valve (PV-002D). Switch over control of the pegging steam flow to the High Range LP Pegging Steam Control Valve (PV-001D). Completely close the Low Range LP Pegging Steam Control Valve (PV-002D). Modulate open / closed the High Range LP Pegging Steam Control Valve (PV-001D) to maintain Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) at 3.49 barg (4.50 bara). The High Range LP Pegging Steam Line will automatically be drained of condensate for 5 minutes using the High Range LP Pegging Steam Drain Valve (HV-004D) prior to opening the High Range LP Pegging Steam Control Valve (PV-001D) if the line has been out of service for at least one (1) hour.

When the required pegging steam is more than the available LP steam, the IP Pegging Steam Control Valve (PV-003D) is to be enabled and modulated open / closed in conjunction with High Range LP Pegging Steam Control Valve (PV-001D) to maintain Deaerator set pressure. The IP Pegging Steam Line will automatically be drained of condensate for 5 minutes using the IP Pegging Steam Drain Valve

(HV-008D) prior to opening the IP Pegging Steam Control Valve (PV-003D) if the line has been out of service for at least one (1) hour.

NOTE: While the IP Pegging Steam Control Valve (PV-003D) is being used to maintain the Deaerator Storage Tank pressure at 3.49 barg (4.50 bara) the High Range LP Pegging Steam Control Valve (PV-001D) is to be maintained at 70% of the fully open position

During startup, control setpoint for Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) will be set at 3.49 barg (4.50 bara).

For Startup on All Fuels:

22. When a measurable HP steam flow is established (approximately 10% of full flow), the HP steam section is “on line” and the HP Main Steam Outlet Stop Valve (HV-001) may be opened and the HP Startup Vent Valve (HV-342) may be closed. Close the bypass on the HP Main Steam Outlet Stop Valve (HV-001A) if opened for warming the piping.

23. When a measurable IP steam flow is established (approximately 10% of full flow), the IP steam section is “on line” and the IP Startup Vent Valve (HV-600) may be closed.

24. The Condenser is available when the vacuum has been established. At that time, the HRH to Condenser Bypass is ready to be engaged. The RH section is “on line”

and the RH Outlet Startup Vent Valve (FV-780) may be closed over a period of 2 minutes. Prior to the Condenser being available, the RH Outlet Vent Valve (FV-780) will modulate open / closed in order to maintain a minimum pressure of 10.99 barg (12.00 bara) at the HRH Outlet (PIT-780A and PIT-780B).

Note that the RH Outlet Startup Vent Valve may remain open up to but not exceeding 50% flow rate.

25. Once the LP Turbine is ready to receive steam, the LP Startup Vent Valve (FV-915) may be closed.

Note that the LP Startup Vent Valve (FV-915) may remain open up to but not exceeding 100% flow rate.

26. The water level set points in the feedwater control system for the HP, IP, and LP Drums and Deaerator Storage Tank will return to the normal operating water level settings automatically when the respective system steam flow > 10%.

Flowrates by Pressure Section (kg/s) Normal Op. Setpoints

(Case 1)

Startup Setpoints

Section 100% 10%

HP 71.19 7.12

HRH 81.57 8.16

IP 11.54 1.15

LP 8.94 0.89

DA 91.30 9.13

ALSTOM Power Revision: 0 5-9 For Startup on Natural Gas Operation:

27. Prior to beginning the final temperature step increase of the GT while operating at 50% load, complete the following change-overs:

• Disengage the bypass of the Condensate Preheater by turning on the Preheater Recirculation Pump (PMP-040) and opening the Recirculation Pump Discharge Control Valve (TV-040) to 100% open.

To prevent thermal shock of the Preheater manifold, keep the Condensate Preheater Bypass Stop Valve (HV-003) open for 15 minutes after opening the Condensate Preheater Feedwater Stop Valve (HV-002).

Set Feedwater Heater Recirculation Control in AUTO mode.

The amount of recirculation flow should be such that the temperature entering the Condensate Preheater (TE-005A and TE-005B) is at or above the set point of 51.7°C. (Refer to Condensate Preheater Recirculation Operation section.) A minimum temperature differential of approximately 2.5°C must be maintained between the saturation temperature in the Deaerator based on the operating pressure (PIT-001D and PIT-002D) and the incoming feedwater temperature (TE-066A & B) in order to ensure proper operation of the Deaerator.

• The Low Range LP Pegging Steam Control Valve (PV-002D) should be in AUTO mode so as to be able to control the pegging steam flow to the Deaerator as the total required pegging steam flow decreases.

As the temperature of the feedwater entering the Deaerator increases the total amount of pegging steam required while maintaining the Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) at 0.99 barg (2.00 bara) will decrease.

Modulate closed as required the IP Pegging Steam Control Valve (PV-003D) first and then the High Range LP Pegging Steam Control Valve (PV-001D). Prior to completely closing the High Range LP Pegging Steam Control Valve (PV-001D), switch control of the LP pegging steam flow over to the Low Range Pegging Steam Control Valve (PV-002D). The Low Range LP Pegging Steam Line will automatically be drained of condensate for 5 minutes using the Low Range LP Pegging Steam Drain Valve (HV-072D) prior to opening the Low Range LP Pegging Steam Control Valve (PV-002D) if the line has been out of service for at least one (1) hour.

28. Once the GT has reached Base Load, change the control setpoint for the Deaerator Storage Tank Pressure (PIT-001D and PIT-002D) to 0.49 barg (1.50 bara).

For Startup on All Fuels:

29. Open the following continuous blowdown isolation valves:

a. HP Drum Continuous Blowdown Stop Valve (HV-181).

b. IP Drum Continuous Blowdown Stop Valve (HV-482).

c. LP Drum Continuous Blowdown Stop Valve (HV-827).

Blowdown flow should be controlled with the following valves:

a. HP Drum Continuous Blowdown Metering Valve (HV-182).

b. IP Drum Continuous Blowdown Metering Valve (HV-484).

c. LP Drum Continuous Blowdown Metering Valve (HV-829).