Dadri Stage-1 Start up Write-up

 

SOP to avoid unit disturbance/tripping during litup/turbine rolling/unit synchronization

1.    APH oil carryover probe to be checked hourly during light up. Oil gun having poor flame to be removed. APH soot blowing to  continue till oil guns in service. CBD to be opened after boiler litup and closed as per chemistry clearance. SCAPH charging &Dearator heating / pegging to be done . Condensate dumping to be done.

Dadri stage-1 Turbine Interlock & Protection

 Dadri stage-1 Turbine Interlock & Protection

• Lub Oil Pr: Alarm=2.0 ksc. Trip=1.88 ksc Effect: Turbine Trips, Barring gear Protection Close,Vacuum Breaker Opens

ATT-200 MW

 

Dadri U-1 functional Loocation /Job Card Help

 

Functional loc. 1011-S1U01 Valid From 20.08.17
Description STAGE-1 UNIT-1

HP Bypass . LP Bypass Operation

Dadri stage-1 Reserve Shut down Procedure

 PROCEDURE FOR RESERVE SHUT DOWN OF STAGE-1 UNITS

PREPARATIONS

Dadri stage-1 : ST-1, ST-2 Both tripping

 In case of both station transformer tripping following disturbance will be observed

SOP for Mills Operation along with Bio Mass

 1) Mill Operating Parameters and Operation procedure:

Work Instructions

Start-Up After 8 Hours of Shutdown ( Hot start-UP)

Unit condition

1	At least 2 BCW pump in Serrvice
2	Both SAPH and PAPH Running
3	Turbine : On Barring (AOP,JOP,SOP, HPCF in service)
4	Generator: PW system, Seal Oil system, Gas system

SCED Features

SCED Features

• NLDC has opened a separate bank account called ‘National Pool Account (SCED)’. All payments to/from the generators and to the Discoms on account of SCED flow to/from the said National Pool Account (SCED)

Power Terminology

Power Terminology

• 100MW for 24 Hrs = 2.4 MU (Million Units)
• Ancillary services refer to functions that help grid operators maintain a reliable electricity system.
• Ancillary services maintain the proper flow and direction of electricity, address imbalances between supply and demand, and help the system recover after a power system event

RH Metal Temp Optimization

RH Metal Temp Optimization

• Causes of Rh Tube Fail:  

(a) COAL ASH CORROSION FOR TUBING
(b) UNEVEN TEMPERATURE DISTRIBUTION ACROSS THE BOILER

Dry Ash system : 500 MW

Dry Ash system : 500 MW

• Ash is oxidised form of the mineral matters present in coal
• Typical ash composition : SiO2, Al2O3, Fe2O3, CaO, MgO etc
• Coal with more SiO2 & Al2O3, Ash MP > 1400ºC

Shut-Down Procedure: 500 MW (Planned Shutdown)

Shut-Down Procedure: 500 MW

• Reduce load from 500 MW to 400 MW
• Gradualy Reduce Pr SP from 170 ksc to 130 ksc, Load is still 400 MW
• Take unit of TFM

New Regulation: Real Time Market Power Trading

Hydrogen Purging

Pre-Purging checklist:

1. The generator may be on barring gear or at standstill. Preferably be on barring speed of around 50-80rpm (without condenser vacuum).
 At least 60 CO2 filled cylinders should be available in the unit where purging is to be done.
 Arrangement for filling hot water on CO2 cylinder / lines (to avoid freezing) is to be ready.

Loss of Instrument Air

Loss of Instrument Air
Anticipated Problems:

1. No oil burner can be taken in service. Oil guns, oil/steam valves will remain inoperative.
The igniter will not get advance.

Vacuum Pulling Process

Vacuum Pulling Process
1 Ensure permit cancellation on Vacuum pump/Flash Tank related MOV/Condensate system & Clearance for vacuum pulling.

Mill Fire

Mill Fire
a) Fire in mill under shut down:
 Isolate the mill totally from air side by closing cold/hot air dampers & gates and mill seal air valves.

Shutdown Instructions

Shutdown Instructions
1 Ensure UT change over before tripping of boiler/ turbine.
2 Ensure 400 KV breaker are opened after unit tripping.

UPS Failure

UPS Failure

CONSEQUENCES OF 240 VOLT UPS SUPPLY FAILURE:-

 All LVS supplies from main UPS will not be available but from mini UPS supply will be
available for around 2 hours .

Boiler forced Cooling

Boiler Forced Cooling

1 In case of Tube leakage

1.1 After Tripping the boiler ,stop FD fan and keep ID fan running at
minimum load and ensure furnace pressure negative inside boiler.

CC(BCW) Pump Isolation & Purging

CC(BCW) Pump Isolation & Purging

1. ISOLATION OF CC PUMP REMARKS

1.1 Remove from Stand by mode if it is in auto
1.2 Stop CC pump if running

Bunker fire : Prevention

Bunker fire

PREVENTION OF BUNKER FIRE

 Ensure Feeder outlet gate closes on auto when Feeder stopped/tripped. Otherwise give
a close command for closing.

ACW pump house

Condenser : One Pass Isolation

1 Ensure the availability of both condenser de-watering pumps.
2 Decrease the load to 300 – 350 MW
3 Ensure that both CW interconnection valve are opened
4 Start Stand by Vacuum pump

Generator Air tightness Test

TEST PROCEDURE: -
1) Air Filling valve is to be opened for flushing of line & removal of moisture in atmosphere.
2) Chemistry is to take sample for dew point measurement. After chemistry clearance , Filling process
has to be continued.
3) Close the waste gas (vent) valves.

APH Hot Washing

1 Water washing of air heaters should be carried out in hot condition after boiler shutdown.Flue gas inlet temperature should be between 200 deg C to 150 deg C
2 Both FD/ID/PA fans should be in stopped condition
3 All APH flue gas outlet damper should be closed

Stopping one FD Fan

1 Reduce the load to 400 MW & then remove from CMC
2 Before Unloading FD Fan (to be stopped ),The following
Permissive & Protection to be kept bypassed :
“FD Fan ON & Discharge Gate close” permissive to be given
“FD Fan ON & Discharge gate auto open” to be bypassed.

Stopping one PA Fan

1 Reduce the load to 300 MW & then remove from CMC
2 Keep 4 consecutive Mills in service. If required , take oil guns in service

Stopping one ID Fan

1. Reduce Load to 300MW
2. Start Unloading corresponding FD fan & increase loading of other FD Fan through blade pitch.

Stopping one PAPH

• Reduce Load to 300MW
• Slowly close flue gas outlet damper for PAPH which has to be stopped

Stopping one SAPH

• Reduce Load to 300MW
• Slowly close flue gas outlet damper (2 in no. )for APH which has to be stopped
• Adjust other PAPH/SAPH flue gas outlet damper
• Close flue gas inlet damper
• Close SCAPH inlet , outlet & bypass damper. During Closing , Observe Air Flow.
• Close SAPH air outlet damper (2 in no.)
• Stop the SAPH motor once flue gas inlet temperature reduced below 150deg C
• Close Air motor main isolating valve & bypass isolating valve

LIGHT UP CHECK POINTS

BEFORE LIGHT UP ACTIVITIES

BOILER SIDE

• MAN ,MATERIAL REMOVED AND BOILER IS READY FOR LIGHT UP.
  

Water-chemistry: 500 MW

Recommended Parameter Values
1. Boiler Water – pH = 9.1-9.4
2. Boiler Water – Specific Conductivity < 20.0 μs/cm
3. Boiler Water – Silica < 100 ppb
4. Boiler Water - Phosphate = 1-2 ppm
5. Boiler Water - Chloride < 0.5 ppm

Check List (Light-Up)

Unit:

Date:

Switchyard Breaker arrangement: Rihand

Stage-I

GT#1  à 1-52  Main (GCB to Bus Bar-1) à 2-52 (Tie-GCB to bus Bar-2) à 3-52(IBT-1 i/c)

GT#2 à 7-52Main (GCB to Bus Bar-2) à 8-52((Tie-GCB to bus Bar-1)

Bus bar-1 à 4-52 (H1) à 5-52(Tie H1-S2) à 6-52(S2) à Bus Bar-2

Bus bar-2 à 10-52 (S1) à 11-52(Tie S1-H2) à 12-52(H2) à Bus Bar-1

Bus-1  ß13-52(Bus-coupler-1) à Bus-3

Bus-2  ß14-52(Bus-coupler-2) à Bus-4

Turbine Governing system

Key Points

Ø  Governing- Regulation of Turbine Speed under No Load and Varying Load

Ø  Others Works: CV Actuation/ Initial Run-up & Synchronization/ Load Variation to meet Grid Freq

Ø  500 MW KWU: Throttle Governed Machine

Ø  2 Governors , EHC and HG connected in Parallel: Only One at a time through Hyd Minimum slection

Ø  CVs Open according to Secondary oil Pressure

Ø  Between 100 MW  to 525 MW , Load variation done by HPCV throttling

Important Procedures

Vacuum Pulling : Procedure:

Ø  Close RH Vents, CRH, HRH UFT drains

Ø  Close Vacuum Breaker

Ø  Open 8.5 m steam Manual valve full Both (100%), Temp> 250 Deg ( Open

Ø  Start GSC Exhauster Fan

Ø  Start Both Vacuum pumps ( Casing Empty, Receiver tank Level adeq)

Ø  At -0.2 ksc charge steam gradually ( lower Controller from 50% à 0 %)

Ø  Build Vacuum upto -0.9 ksc

Hydrogen Purging

Ø  SLC AS SOP Off, SLC DC SOP Off, SLC H2 SOP Off

Ø  Suppy of DC SOP Off

Ø  Start one AC SOP ( DP=1.5 ksc)

Ø  Dew Point Air=<-10 Deg, clearance from Chemist

Ø  H2 (Isolated Position), CO2(Isolated Position), Air Inlet(Open), Casing vent ( Closed)

Ø  Fill and Pressurise upto 0.5 ksc

Cold start-up

Points to Remember

Ø  maximum of HP casing and HP shaft is less than 150°C(more than 5 days)

Ø  It requires soaking of Turbine at 360 rpm with steam(40ksc,360 Deg)

Ø  An upper limit of 200° C/hr. saturation temp gradients can be allowed, i.e. approximately the boiler pressure can be brought to 20 Kg/ Cm² within an hour of cold start up

Ø  But actual temp gradient is limited by the thick walled Y piece provided in the main steam and HRH lines

Ø  maximum differential temp allowed between inner (98%) and mid wall temp (50%) is ±40°C

Ø  Start only two CC pumps in order to minimize flashing in down comers (and subsequent vibration) when the boiler water is in the range of 85° to 125° C

IBT Outage

Consequences on Stage-2 ( Station Transformer Tripped)

Ø  132 KV Switchyard dead results in tripping of -Station Transformers, Construction Transformer, Misc Transformer

Ø  All colony power( Lighting,Water supply) will get interrupted

Ø  Power Supply to DM Plant, HFO Pump house, PTCW Pump house, Offsite Board, ADPH,

Ø  Following Board will get dead:

§  OBA,OBB,OBC,OBD (11 KV station Board)

§  OCA,OCB (3.3 KV Station aux Board), ADPH MCC, CHP Transformers

§  DMPT, CWST, WTPT,BTST,ODA,ODB(Station Service), ODC(FW Pump House),ODD ( Offsite ): 3.3 KV

§  OQA,OQB(St. Serv),3SA,4SA(Air Washer MCC),3TA,4TA(Unit Ventilation MCC),OTA(HVAC ) : 415 V

§  OSA(SW MCC), OTB(Serv Bldg Ventilation MCC), FOPH : 415 V

Main Equipments Tripped

Instrument Air supply Failure

Reasons of  Failure:

Ø  Failure of control supply of  compressor

Ø  Loss of Cooling Water (SG ECW Pump Trip)

Ø  Massive leakage in  IA supply Header

Ø  One Unit Under Overhaul. Unit Aux Board/ Station Aux board  got Tripped of that Unit

Ø  Total Black Out of any stage

DG Load Trial and Regular checks

Requirements:

1	Inform & Ensure availability of TMD/EMD/C&I
2	SG/TG/BOP source-2 AC Power Supply Interruption. Inform C&I for Standby chargers
3	Ensure DG Set Tank Oil Level Adequate
4	Evacuate and Isolate Boiler Passenger, Service Building Lift and Isolate. Inform EMD(temporary supply )
5	Arrange 3 Walky Talky : 1-CR 2-DG board 3-DG Set room
6	Note Down Initial Parameters of DG Set

Furnace Air Tightness Test

Ø  Scope- Boiler Furnace, Air and FG Duct upto ID Fan Inlet

Ø  Why- To test Tightness of Furnace wrt Environment not for Strength

Ø  Ensure- All PTWs of BMD( PP, Rotary, Mills, Ash handling) cancelled and Clearance Available

Emergency Instructions:220 V DC Failure

220 V DC Failure

Unit condition

Ø  DCDB section-1 & 2 under voltage alarm in LVS-5

Ø  All HT/LT Breakers Indication Becomes Bad

Ø  Boiler will Trip on MFT ( after 2 Sec)

Ø  Turbine will Trip on MFT

Ø  Generator will not Trip as GCB Protection will not act

Ø  Generator will run as Synchronous Motor

Start-Up After 8 Hours of Shutdown ( Hot start-UP)

Unit condition

1	At least 2 BCW pump in Serrvice
2	Both SAPH and PAPH Running
3	Turbine : On Barring (AOP,JOP,SOP, HPCF  in service)
4	Generator: PW system, Seal Oil system, Gas system
5	Condenser Pass : Both Charged
6	PAC & IAC : 1 PAC & 2 IAC in Service
7	CEP & Make-up :  1 CEP with H/W Make-up on auto

Tripping on Boiler Tube Leakage