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Cold Start

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1.0   Purpose

2.0   Overview

3.0   Procedure

3.1   Limits and Precautions

3.2   Checks and Tests

3.3   Startup

3.3.1   Cold Start Validation Checklist

3.3.2   Control Room Activity Checksheet

3.3.3   Gas Turbine Pre-Start Checklist

3.3.4   Plant Operator Prestart Checklist

3.3.5   Start-up Procedure (Cold Start)

3.3.6   Steam Turbine Pre-Start Checklist

3.3.7   STG Start-up

3.4   Normal Loading


1.0   Purpose

The purpose of this procedure is to outline the key tasks and the method that will be used to conduct a cold start of the plant. Cold start is defined as the starting of the Steam Turbine with a 1st stage or RH bowl inner-metal temperature of less than 400F.

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2.0   Overview

The normal combined cycle cold startup will be completed by initiating 1x1 operation and then combining the second combustion turbine/HRSG steam production together at elevated loads by opening the steam header block valves. The other method of starting would involve the unit headers connected to the common header prior to a combustion turbine start. Both combustion turbines would be started and the HRSG’s warmed at approximately the same time. The second method would speed up the startup process but would take more actions on the part of the plant operators.

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3.0   Procedure

3.1   Limits and Precautions

General Plant

  • All Tagging activities must be audited and cleared prior to beginning the checklist for system operation.
  • All Hot Work should be verified completed and filed.
  • All Confined Space activities on the Units in start-up completed and filed.
  • Temporary standing orders will be reviewed and any lead lifting and jumper log activities shall be audited in accordance with PPM 5.0.
  • The operations start-up step sequence will be completed IAW 10.01. Enclosure 1.0.
  • The normal system line-ups should be verified in accordance with PPM 9.0 for any system that has been taken out of service for the shutdown.
  • All the Steam Turbine Units should be placed on turning gear 4 hours prior to starting and the CTG’s should be in cool down mode and ready to start.
  • Power and Gas nomination sheets should be submitted per the schedule prior to operations. See PPM 4.0 for Dispatching Electric Power.
  • Plant chemistry program should be placed in service and overall water availability and quality should be validated prior to starting the plant.
  • The CEMS should be operational and all daily reports verified correct and system checks completed.

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3.2 Checks and Tests

CTG’s

  • Verify that the Units are ready to start.
  • Complete the operational checklist.
  • Sump oil temperature should be between 90 – 110 F.
  • Verify the MK V control systems are operational.
  • Verify the units are on gear and ready to start.

HRSG

  • The HRSG must be completely filled with high quality chemically treated demineralized water.
  • The entire HRSG should be walked down and vented to verify that air pockets have been eliminated during the fill process.
  • All HRSG system valves need to be properly positioned for HRSG startup.
  • All HRSG system instruments must be functional.
  • The heat tracing system must be functional.
  • All pertinent steam system prerequisites must be satisfied and the steam circuits must be available for operation with valves properly positioned for startup.
  • The cycle chemical feed system and the sampling system should be functional and ready to support operation of the HRSG.

Plant Electric System

  • The plant power system must be back fed from the 500kv system and all breakers in the normal power line-up IAW PPM 9.0.
  • Back feed demand should be limited to 12,000kv for any 15 minute period max during the starting process to stay within the agreement for purchased power.

Fuel Gas System

  • El Paso Gas System should be available and the normal line-up for the plant checked.
  • Gas operations should be notified in accordance with PPM 4.0.

Circulating Water System

  • The cooling tower level should be 35-42”. The circulating water pump should be in service with a minimum of eight cells in service and tower raisers open to minimize drift effects.
  • Cooling tower chemistry should be verified with in range. All treatment systems in service.
  • Visual inspection of screens and fill should be completed if an extended shutdown was performed.

BOP Systems

  • Air compressor system operational and the lag compressors ready for service.
  • Plant water treatment in service and normal levels in all tanks.
  • Feed water system ready for service and drum levels at minimum for cold start.
  • Condensate system ready for service with hotwell level normal.
  • The Air Intake and Exhaust system is ready for operation.  Inlet and exhaust plenums and associated ducting are clean and rid of all foreign objects.  All access doors are secure.
  • All other plant systems ready for start-up in accordance with PPM 9.0.

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3.3 Startup

Once the plant conditions for a cold start are verified (1st stage shell or RH bowl inner metal temperature less than 400F). The Pre-start checklist contained in Enclosure 1.0 shall be completed and maintained to document the required sequence and data for the start-up. The start-up is managed by the control room with individual responsibilities contained in the check sheets of Enclosure 1.0 and identified below.

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3.3.1 Cold Start Validation Checklist

 

Date/Time Start:

______________

CRO:

_______________

 

Unit:

______________

Shift Lead:

_______________

 

Time of dispatch:

______________

   

Indicators
COLD START

Targets

Actuals

Units

Min

Max

         

1. HRH Blending Pressure

-25

25

 

PSI

2. HRH Blending Temp,  

-50

50

 

deg. F

3. HP Blending Pressure

-25

25

 

PSI

4. HP Blending Temperature

-50

50

 

deg. F

5. LP Blending  Pressure

-25

25

 

PSI

6. LP Blending Temperature

-50

50

 

deg. F

8. Time unit is ready for dispatch

     

Current Time

         

Date/Time S/U complete:

________________________

Cold start: 1st stage and RH Bowl inner-metal temperature < 400F

CRO:

________________________

Warm Start: 1st stage and RH Bowl inner-metal temperature between 400 and < 700F

PTL/O&M review:

________________________

Hot Start: 1st stage and RH Bowl inner-metal temperature > 700F

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3.3.2 Control Room Activity Check sheet

Action

Initial/Comment

Review Hot Work Binder

 

Review Confined Space Binder

 

Review LOTO for clearances that will affect Start-up

 

If maintenance was performed complete post maintenance close-out

 

Check and Verify DCS alarms and MKV

 

Review temporary standing orders and night orders, verify compliance with PPM 5.0 Lead Lifting and Jumpering.

 

Ensure CEMS is in operation and clear of alarms, document in the log book by making entry.

 

Ensure Plant Fire System is in service and Auto.

 

Ensure Steam Turbine is on Turning gear and eccentricity reading is less than 3 mils.

 

Verify Plant Chemistry

 

Ensure Demin supply tanks > 60%

 

Verify Demin transfer system in service by placing 1 pump "in service", 1 pump in "auto"

 

Condensate Pump start permissives: 1 demin transfer, condensate recirc regulator open>60%

 

Throttle condensate pump discharge valve 20% open and close BV3030/4030, start pump, upon equalization and venting of the system open the discharge valve to 100%, open BV 3030 place remaining pumps in standby.

 

Start condensate chemical injection pumps

 

Open LP feed water stop valve SGA MBV-1402/2402

 

Fill LP drum to normal level -3" and place level controls in "auto"

 

Establish condenser levels at 30”

 

Start BMS scanner blower fan place other fan in "standby"

 

Check that all the DCS startup permissives are satisfied reset GT at DCS

 

Startup Boiler feed water pump, place other Boiler Feed water pump in standby

 

Start HRSG chemical injection pumps, fill HP drum up to -12”,IP drum up to -10” place feed water control valves in auto.

 

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3.3.3 Gas Turbine Pre-Start Checklist (Control Room Operator)

Initial Each Item as Completed

_______Perform a “Master Reset” on the MKV

_______On Mark V HMI, check all bearing drain, metal, and exhaust thermocouples are reading good quality.

_______On Mark V HMI, check Generator RTD’s are reading good quality.

_______On Mark V HMI, check Generator H2 pressure and purity w/in specifications.

_______On Mark V HMI, check gas valves position’s, all should be 0% open.

_______On Mark V HMI, verify all flame detector intensities are reading: 1or 0.

_______On Mark VI HMI, verify IGV control in Auto, IBH is on, IGV temp control is on, FSR Control is in Auto, and steam turbine temperature matching is off. (Temp match TBD)

_______On Mark V HMI, verify all seismic vibration probes have good readings 0.00 – 0.02

_______On Mark V HMI, check start check screen for all green except for “Control Mode equals Off”

_______On Mark V HMI, check trips screen for all green except for “Fuel Gas Hydraulic Pressure Low Trip”

_______Ensure Lube oil temperature is > 90 F.

_______From Mark V HMI, record all alarm drop numbers for specified unit below:

Comments:

 

 

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3.3.4 Plant Operator Pre-start Checklist

Note: If GT readings (outside/Local) have been performed within the last 2 hours, perform only the following checklist: Otherwise, perform GT system walkdown as prescribed by operator logs.

Action

Initial/comment

Check the items below following for oil, water and containment. Verify doors closed and latched.

 

Accessory Compartment

 

Gas Compartment

 

Turbine Compartment

 

Collector End Compartment

 

Seal Oil Compartment

 

Check EX2000 Panel for alarms

 

Ensure 41AC breaker is racked in, EX2000 core breakers are energized, and fans are running.

 

Check LCI for alarms

 

Check Generator Protection Panel, ensure there are no flags on any relays and ensure all three phases are reading good voltage

 

Verify Hydrogen Purity >98% and Scavenging Flow ~500 cc/analyzer

 

Verify Units on Turning Gear

 

Check the CO2 fire protection system for alarms, ensure manual isolation valves are open and all compartment valves are in neutral position.

 

Comments:

 

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 3.3.5 Start-up Procedure (Cold Start)

_______Open HRSG start up drain valves ,close at >10psi of starting pressure

_______Close all N2 feed valves to HP, IP, and LP drums

_______Place Aux header drains ABV-X005, X006, X016,in auto

_______Open all steam line drains:

  • HP ABV-X141, X017, X019, X020, X001, X002, X011, X012
  • IP ABV-X004, X005, X017, X001, X002, X005, X009
  • CRH-ABV-X010, X019
  • LP ABV-X006, X022, X009

_______Place HP to CRH bypass in auto, set point of 600 PSI

_______Place all start up vents in following position

  • Auto closed, HP MCV-X139/X139
  • Auto closed, IP SH MCV-X314/X314
  • Auto closed , HRH MCV-X627/X627.  Ensure HRH Bypass valve has a setpoint of 125 psi
  • Auto closed , LP MCV-X518/X518

_______Ensure all HP and IP attemperators are in auto with a setpoint of 1000 deg.

_______Ensure the following motor operated steam valves are closed for the lag GT:

  • 1SGG-MBV-X001/X001 (HP Steam stop valve)
  • 1SGJ-MBV-X001/X001 (HRH isolation valve MOV)
  • 1SGH-MBVX013/X013 (LP Steam stop MOV)
  • 1SGK-MBVX012/X012 (CRH Isolation valve)

_______Start GT from the MK V as follows:

_______Perform Master Reset

_______Ensure mode select is in Auto,

_______Select  start

_______Record GT start time in control log

_______Place SCR Blower in service. Place lag blower in sand by mode

Perform the following valve lineup during the GT purge cycle for the starting GT:

_______Open 1SGJ-MBV-X001/X001,X316/X316 (HRH isolation valve)

_______Open 1SGG-MBV-X001/X001 (HP Steam stop valve)

_______Open1SGH-MBVX013/X013 (LP Steam stop valve)

_______Open1SGK-MBVX012/X012 (CRH Isolation valve)

_______Open1SGA-MBV X316/X316 (IP SH isolation valve)

_______Ensure IP Back Press Control (1SGA-ACV X315/X315) is at 250 psi and in auto

_______Record each GT fire time in log book

_______Place electric Fuel Gas start up heater in service

_______Record time for each GT when generator breaker closes.

_______Increase GT load to obtain the lowest possible NOx and CO emissions in mode 3 (TTRF < 2000F)

_______When pressure in the HP,IP, sections reaches >10 psi close HRSG start up drains.

_______When steam quality is obtained place steam seals in service at 3.5 psi (min 175 psi in HP header, 300 F min)

_______Start gland exhauster blower (1-BLO-X00 A/B) place lag blower on standby

_______Place both condenser vacuum pumps in service, if not previously done .

_______Close vacuum breaker.

_______At 4.91 psia bypass operation may commence (20” vacuum)

_______Place RH bypass valve (SGJ-1001) in auto, set point of 125 psi monitor drum levels closely; once condenser bypass has commenced.

_______ When pressure in the condenser reaches 2.5 psia vacuum secure one pump and place in standby start up vent HRH MCV-X627/X627.

_______Place LP bypass valve in auto with a set point of 55-psi.

_______Raise LP start up vent pressure set point to 90-psi

_______With all HRSG steam bypass valves in auto and HRSG pressures stabilized place GT in temperature matching

_______Close all steam line drains and place in auto except (STG Start Permissive):

  • HP ABV-X011,X012
  • IP ABV-X001,X002,X005,X006

_______GT IGV angle will open to maintain desired exhaust temperature

_______Review STG pre-start check list.

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3.3.6 Steam Turbine Pre-Start Checklist:

Control Room Operator:

Action

Initial / Comment

Ensure 86G lockouts are reset

 

On the MKV ensure that all bearing drain , metal, and exhaust thermocouples are reading good quality.

 

Check EX2000 Faults

 

Verify Hydrogen Purity > 98% and Scavenging flow > 500cc

 

Verify STG is on Turning Gear (eccentricity < 3mills)

 

Ensure all MKV, HMI permissives are satisfied.

 

Verify all Group A, B, C Drains are in “Auto” on the MKV

 

Verify Lube Oil Temp > 80 F.

 
Record Condenser vacuum, < 2.5 psia required to roll  

Lower RH Steam Pressure to 60 PSI prior to Roll

 

While on turning gear the HP and Reheat section should be prewarmed to 75-130 F for 20 minuets by operation of the steam seals. No prewarming is needed if the HP/reheat bowel inner surface metal temperature is over 130 F.

NOTE:  IF OPERATOR ROUNDS HAVE NOT BEEN PERFORMED WITHIN THE LAST 2 HOURS PLEASE RECHECK ITEMS PERTAINING TO ONLY STG IN THE OPERATOR LOG SHEETS 1-3

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3.3.7 STG Start-up

Note: If performing a manual start, refer to GE “Starting and Loading Instructions” (GEK 55127) Vol III Tab 1

_______On the MK V HMI Perform a Master Rest

_______On the MK V HMI select Auto Start

_______On the MK V HMI Select Speed Hold off

_______On the MK V HMISelect Turbine Start

During the roll closely monitor the following

_______HP exhaust temperature limits

Alarm 850  F

Trip 900degF

_______LP temperature limits

Alarm 400  F

Trip 450  F

_______Exhaust temperature limits

Alarm 200  F

Trip 225  F

Note:  Trip turbine immediately if vibration exceeds 10 mills.

_______Differential expansion limits

Alarm DEDX-1 long rotor + 386

Trip DEDX-1 long rotor + 486

_______Differential expansion limits

Alarm REDX-1 long rotor + 616

Trip REDX-1 long rotor + 720

Alarm DEDX-1 short rotor-260

Trip DEDX-1 short rotor -290

Alarm REDX-1 short rotor -287

Trip DEDX-1 short rotor -317

Note: It is recommended that reheat steam be maintained < 700 degf prior to roll. Also keep hot reheat pressure in the range of 60-125 PSI to maintain the steam to metal temperature mismatch (HP/reheat bowl) below 400 F.

_______Verify the Turbine speed reaches 800 RPM and HEAT SOAK (1) is displayed. This will be maintained until specified heat soak time is reached. Turbine speed will hold at 3000 RPM until lube oil temperature reaches approximately 100 F. Continue to raise temp, matching set point and monitor steam to metal mismatch (reheat bowel inner ).

_______Verify the lube oil heat soak is satisfied and the MK V will automatically increase the turbine speed to3600 RPM.

_______Synchronize Steam Turbine to the grid.

_______Select load control to 14%, MK V will hold STG load at approximately 10% until look ahead stress calculations are within tolerances.

_______Increase temp matching set point in 25 F increments until GT IGV is at min 44 degree angle. Maintain steam to metal mismatch (reheat bowel inner) below < 300  F

_______Upon completion of load hold MK V will allow STG to ramp; when IV flow demand exceeds 50% transfer to forward flow will occur.

_______Ensure HP to CRH and, REHEAT BYPASS valves close select a setpoint of 1200 psi on HP to CRH and 350 PSI and place in calculated set point

_______With GT IGV angle at minimum 44 degrees, deselect temperature matching and raise GT load to 33 MW.

_______On MK V HMI Set LP steam flow set point to 20% continue to raise set point in 10% increments. When AVC valve opens >5% select LP steam flow set point to 100%.

_______Slowly close LP bypass valve by raising set point to 90 psi .

_______Secure fuel gas electric start up heater.

_______With fuel gas temp > 320 F raise GT load to obtain mode 6Q

_______As HP pressure recovers > 800 psi place STG in IPC mode select IPC set point to 600psi.

_______Raise GT load in accordance with schedule set HP,IP cont blow downs and chemical pump strokes as necessary to support HRSG chemistry.

_______Close all remaining steam line drain and place in auto

_______Start condensate pumps, second circulating water pump and cooling tower fans as necessary..

_______Raise drum levels back to normal on both HRSGs.

_______Verify HRSG in 3-element drum level control.

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3.4 Normal Loading

Maintain Generator VARS at unity at all times unless director by SRP dispatch. Normal loading is accomplished by adjusting the load set-point on the turbine overview screen. Monitor and maintain load within the PaloVerdi congestion management set point for the day as nominated in PPM 4.0.

4.0 REFERENCES

GEK

GE Manuals Gas and Steam Turbines

NE Manuals

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