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Lag Unit 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   Lag Unit Start Validation Checklist

3.3.2   Control Room Activity Checksheet

3.3.3   Gas Turbine Pre-Start Checklist

3.3.4 Plant Operator Pre-start Checklist7

3.3.5 Start-up Procedure (Hot Start)

3.4 Normal Loading

1.0   Purpose

The purpose of this procedure is to outline the Tasks necessary to bring a Lag Unit into service and ensure compliance with the Air Quality Permit Emissions limits and recommended ramping of the Unit.

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2.0   Overview

The normal combined cycle cold or hot startup will be completed by initiating 1x1 operation and then combining the second combustion turbine/HRSG steam production together at elevated loads.   

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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 jumpering activities shall be audited in accordance with PPM 5.0 .
  • 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.
  • CTG's should be in cool down mode and ready to start. 4 hours prior to light off
  • Verify Power and Gas nomination sheets with S.E.T. prior to light off
  • 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

Verify that the normal system line-ups have been competed and that the support systems are operating in accordance with PPM 9.0 .

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3.3 Startup 

Once the plant conditions are ready for starting and the Lag Unit is verified. The Pre-start checklist below 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 identified below.

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3.3.1 Lag Unit Start Validation Checklist  

Verify and Log the following conditions on the running unit prior to blending.







HP Steam



LP Steam





Date/Time Start:







Shift Lead:



Time of dispatch:















1. HRH Blending Pressure





2. HRH Blending Temp,  




deg. F

3. HP Blending Pressure





4. HP Blending Temperature




deg. F

5. LP Blending  Pressure





6. LP Blending Temperature




deg. F

8. Time unit is ready for dispatch




Current Time







Date/Time S/U complete:


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



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

PTL/O&M review:


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

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3.3.2 Control Room Activity Check sheet



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 RTDs are reading good quality.

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

_______On Mark V HMI, check gas valves positions, 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 >85F.

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



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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 .



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.




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3.3.5 Start-up Procedure for Lag Unit

_______Ensure the following MBVs are in manual and closed for the lag GT:

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

_______Ensure Start-up vents are in auto.

_______Place HP Steam bypass valve in auto and ensure in calculated setpoint.

_______If HRSG has no steam pressure open all HRSG and header drains upstream of steam stops. Keep open until a 10-25# raise in pressure. If HRSG has pressure open all drains for 5 minutes.

Start GT from the MKV as follows:

_______Master reset

_______Mode select AUTO,

_______Select Start

_______ Record GT Start Time

_______Start SCR Blower, place ammonia control regulator in auto.

_______Check the attemperators to be in “AUTO”.

_______ Record GT Fire Time. Ensure steam path exists. Verify HP bypass opens and HRH S/U vent opens to at least 12%.

_______Place electric fuel gas heater in service.

_______Place (HRH bypass) 1SGJ-ACV-X008/X008 in “AUTO” when HP to HRH steam flow is greater than 75kpph with pressure set point in calculated setpoint.

_______Place (LP bypass) 1SGH-ACV-X010/X020 in “AUTO” with pressure set point matching lead unit's actual pressure.

_______Record GT Breaker Close Time.

_______Preselect load to 33 MWs. Slowly walk MW's up until TTRF is as close to 2000F without exceeding. This expedites heating of fuel gas and activating CO catalyst and heating HRSG to allow ammonia spray for NOx controls.

_______As soon as Fuel Gas temperature requirements have been met raise GT load to 90 MW maintain mode 6Q, trim load off running units in order to maintain load requirements.

Note : Lower drum levels on lead unit to -5” in anticipation of swells during blend. Monitor drum levels frequently during blend.

_______Match temp/press as defined on the startup worksheet, then open steam block valves as follows:

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

_______After blending LP steam raise LP bypass set point to 90 psi.

_______Adjust plant load as necessary to support generation schedule.

_______Check VARS maintain at unity.

_______Set continuous blow down settings to previous setting.

_______Align chemical injection pumps as necessary.

_______Slowly 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

Normal loading is accomplished by adjusting the load setpoint on the turbine overview screen.  Ensure generator stays within the reactive capability curves. Monitor and maintain load within the PaloVerdi congestion management set point for the day as nominated in PPM 4.0 .

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