1

MAIN BOILER

Make – BHEL Type Natural Circulation Dry Bottom Single Drum Tangential Fired Balanced Draft Radiant Reheat Type with Direct Corner Fired Pulverised Coal System

Coal Analysis F.C – 25% ; V.M – 20% ; Moisture – 15% ; Ash – 40% CV – 3200 kcal / kg U.H.V = 8900 – 130 (A + M) kcal UHV – Useful Heat Value

A – Ash M – Moisture

Superheater DRUM

PLATEN PENDENT SUPERHEATER SUPERHEATER FURNACE

S T A C K

ID FAN

2

Platen Superheater

Heat transfer is mainly due to Radiation.

Q T4 (Temperature) Temp v (velocity of steam)

Pick up (C) T (Temperature difference between heating and heated media)

MW Pendent Superheater Heat transfer is mainly due to Convection.

Q T (Temperature) Temp v (velocity of steam)

Pick up (C) vg (Volume of flue gas)

MW

Normal Operating Values

STEAM CIRCUIT 270C 354C 413C 518C 540C

LTSH PLATEN SH

FINAL SH

BOILER DRUM

HP TURBINE

3

161 ksc 160 ksc 147 ksc

Temperature Limits No. of coils in Boiler

Boiler Tube Metal Temperature LTSH – 120 Platen SH – 29 NORMAL MAX. Final SH - 89

LTSH 445 485 Reheater Front – 59 Platen SH 540 565 Reheater Rear - 59 Final SH 544 565 Economiser – 145 Reheater 575 605

FLOW (T/Hr) OXYGEN v/s LOAD

NCR MCR Steam at Final SH outlet 603 670 Steam at Reheater outlet 533 593 Water at Economiser 592 670 Coal flow (Design) 147 162 Coal flow (Worst) 180 200 Primary Air at APH outlet 194 207 Secondary Air at APH outlet 551 555 Total Combustion Air 790 874

100 150 Recommended Boiler Chemistry Limits

Drum operating pressure (kg/cm2) 60-125 125-165 165-180 Total dissolved solids (ppm) 100 50 25 Sp. Conductivity at 25 C (mho-cm) 200 100 50 Phosphate (ppm) 5-20 5-10 3-7 pH at 25 C 9.1-10 9.1-9.8 9.1-9.8 Silica (ppm) < 0.02 < 0.02 < 0.02

Coal Bunker

Weight Distribution Of Ash : Bottom Ash hoppers – 20% Economizer hoppers – 5% APH hoppers – 5% E.S.P hoppers – 70%

4

Safety Valves Setting :

VALVE NO. SET PRESSURE (kg/cm2)

RESET PRESSURE (kg/cm2)

DRUM : B1 175.8 168.8 DRUM : B2 179.3 170.3 DRUM : B13 181.1 172.0 SH : S-32 163.3 158.4 CRH : R-9 45.5 44.1 HRH : R-19 42.7 41.4

Flue gas path

PLATEN SH REHEATER FINAL SH

1155’C 1014’C 757’C 497’C LTSH 412’C ECONOMISER 143’C

DRAFT (mmwcl)

PLATEN SH Inlet - REHEATER Inlet -6 ECONOMISER Inlet -25 APH Inlet -37

FLAME

S T A C K

DRUM

ID FAN

APH

5

ESP Inlet -153 ID FAN Inlet -200

BOILER AUXILLARIES

Secondary Air Path

320 mmwcl 257 mmwcl 163 mmwcl From Atm. 313C To Furnace

(Windbox to Furnace DP = 140 mmwcl)

FD FAN Start permissives

1. Control oil pr adequate (> 8 ksc) 2. Blade pitch minimum 3. Discharge damper close 4. Bearing temp. Normal (< 60 C) 5. Control & Lub oil temp. Normal (< 55 C) Interlock

1. I.D Fan running Protection

1. Electrical protection 2. Bearing temp high:

Motor – 80 C (A), 95 C (T) Fan – 90 C (A), 105 C (T)

3. I.D fan trip. 4. Control oil pr. < 6.0 kg/cm2 5. Post purge trip from FSSS.

SCANNAR AIR FAN

Interlocks

1. Closing of discharge damper from fan trip or stop.

FD FAN-A

APH-A

APH-B FD FAN-B

6

2. DC scannar air fan will start from AC scannar air fan trip. 3. Emergency damper will open from both FD fans trip.

Primary Air Path

779 mmwcl 740 mmwcl 687 mmwcl Mill-A CAG HAG Mill-B

646 mmwcl Mill-C

Mill-D Mill-E Mill-F 318C

PA FAN

Start permissives

1. IGV minimum 2. Discharge damper close 3. Bearing temp. normal (< 60 C) 4. FSSS start permit (Boiler MFR reset & all cold air dampers are < 5% open) 5. One FD Fan running. Protection

1. Electrical protection 2. Bearing temp high :

Motor – 85 C (A), 95 C (T) Fan – 95 C (A), 105 C (T)

3. P.A header pr. low. 475 mmwcl (A), 375 mmwcl (T) 4. Boiler trip

APH-B PA FAN-B

PA FAN-A

APH-A

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SEAL AIR FAN

Interlocks

1. Closing of discharge damper from fan trip or stop. 2. Seal air discharge to cold air duct DP low. 3. Auto starting of seal air fan on PA fan starting. MILL Permissives

1. PA Fan running. 2. Ignition Permit. 3. Feeder remote. 4. Seal air pressure adequate (> 200 mmwcl) 5. Mill outlet temperature less than 220 F. 6. No unsuccessful start command is persisiting. 7. No pulveriser trip. 8. Tramp iron gate open. Protections

1. EPB pressed. 2. Seal air P low (<125 mmwcl for more than 1 min.) 3. Boiler MFR trip. 4. PA header pressure lo – lo (475 mmwcl – 2/3 logic) 5. Motor electrical protection. 6. If any PA fan trips , top elevation running mills trip and rest 3 mills remain in service. COAL FEEDER Protection 1. Discharge Plugged 2. Belt Deviation – 1st Step (A) ; 2nd Step (T) 3. Mill trip to Feeder trip 4. Hot air gate closed

8

Flue Gas System

-153 mmwcl -200 mmwcl -37 mmwcl -25 mmwcl

ID FAN Start permissives

1. IGV minimum 2. Discharge damper close 3. Bearing temp. normal (< 60 C)

Interlock 1. Gas path through 2. Air heater running

Protection

1. Electrical protection 2. Bearing temp high :

Motor – 75 C (A), 80 C (T) Fan – 95 C (A), 105 C (T)

3. Both APH trip 4. Post purge trip from FSSS.

ESP PASS-A

ESP PASS-B

ESP PASS-C

ESP PASS-D

ECONOMISER

APH-A

APH-B

ID FAN-A

ID FAN-B

C H I M N E Y

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HFO TRIP VALVE Permissives

1. Boiler MFR is reset 2. HFO pressure is adequate ( >10 kg/cm2 ) 3. HFO header temp > 95 C

Protection

1. HFO pressure low (< 3 kg/cm2 ) 2. HFO temp low (< 90 C) 3. Boiler trip

BOILER PROTECTIONS:

1. Flame failure 2. Loss of all fuel 3. Loss of 220V DC to FSSS. 4. Elevation power failure. 5. Boiler load < 30% and air flow <30%. 6. Furnace pressure hi-hi (+100) 7. Furnace pressure lo-lo (-75) 8. Drum level hi-hi (+225) 9. Drum level lo-lo (-225) 10. Reheater protection 11. All BFP’s stopped. 12. Boiler both manual trip buttons pressed. 13. Turbine trip and boiler load > bypass capacity (60%) 14. Loss of ACS power. 15. Both ID fans off 16. Both FD fans off

Loss of All Fuel Protection Logic:

¾ ignitors of any elevation ‘ON’ (ARMED) HOTV closed

All oil nozzle valves closed

Feeder OFF

OR

AND

Loss of All Fuel TRIP

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Boiler Flame Failure logic : Boiler will trip on flame failure when all elevations are ‘VOTED’ in FSSS console. Conditions for VOTED in a single elevation:

Feeder OFF

Elevation power failure

3/4 Safe Scanners intensity < 20%

Flickering Freq.< 2.5 Hz (OIL)/ 26 Hz (COAL)

2/4 nozzle valves not proven

Flame failure protection is armed when 1st feeder is taken into service. Ignition Permit criteria for different Mills : MILL-A ¾ nozzle valves of AB elevation are proven Mill-B loading > 50% Boiler load > 30% MILL-B ¾ nozzle valves of AB elevation are proven Mill-A loading > 50% Boiler load > 30% Mill-C loading > 50% Boiler load > 30%

OR

& Ignition Permit

for Mill-A

OR

&

Ignition Permit for Mill-B

&

OR

AND

VOTED

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MILL-C

¾ nozzle valves of CD elevation are proven Mill-B loading > 50% Boiler load > 30% ¾ nozzle valves of AB elevation are proven Mill-B loading > 50% Mill-D loading > 50% Boiler load > 30% MILL-D ¾ nozzle valves of CD elevation are proven Mill-C loading > 50% Boiler load > 30% Mill-E loading > 50% Boiler load > 30% MILL-E ¾ nozzle valves of EF elevation are proven Mill-D loading > 50% Boiler load > 30% ¾ nozzle valves of CD elevation are proven Mill-D loading > 50% Mill-F loading > 50% Boiler load > 30%

OR

&

Ignition Permit for Mill-C

&

&

OR

&

Ignition Permit for Mill-D

&

OR

&

Ignition Permit for Mill-E

&

&

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MILL-F ¾ nozzle valves of EF elevation are proven Mill-E loading > 50% Boiler load > 30% Drum Level Protection TURBINE IPT LPT (20 X 2) (8 X 2)

ESV 39 ksc IV 34 ksc 334 C 535 C CONDENSER 0.1187 ksc 36 ksc 34 ksc 49 C 335 C 538 C

147 ksc 535 C

OR &

Ignition Permit for Mill-F

REHEATER

HPT (25 X 1)

HPBP LPBP

HW

OR

ACS(L)

HYD(R)

ACS(R)

ACS(L)

ACS(R) HYD(L)

BOILER TRIP

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Turbine Diff. Expansions : ALARM TRIP HP Turbine + 4.5 + 5.5

- 2.5 - 3.5 IP Turbine + 5.0 + 6.0

- 2.0 - 3.0 LP Turbine + 25.2 + 30.2 - 5.0 - 7.0 Cut-in / Cut-out speeds : 1. BARRING GEAR

Cuts In – 250 rpm Cuts Out – 200 rpm

2. J.O.P Cuts In – 540 rpm Cuts Out – 510 rpm

TURBINE PROTECTIONS Main Steam temperature very low ( < 460 C ) Condenser back pressure high ( > 220 mm Hg ) Bearing lub oil pressure lo – lo ( < 2 kg / cm2 ) Axial shift of turbine shaft ( + 1 mm & -1 mm ) Over-speeding ( > 3330 rpm ) Boiler trip to turbine trip. Manual trip Push Button pressed. Fire Protection – 1

1) Push Button pressed 2) Operates automatically when MOT level is < - 50 mm Alarm appears. < - 100 mm Protection operates.

When Fire Protection – 1 acts, Vacuum breaker opens. Turbine comes on barring gear.

When MOT level < - 150 mm MOT level low alarm appears if TG is on barring gear.

Fire Protection – 2 Does not operate automatically. It is operated manually by pressing the Push Button. Then Fire Protection – 1 acts automatically. When Fire Protection – 2 acts , JOP – 2 and EOP starts. Vaccum breaker opens. Turbine does not come on barring gear.

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THERMAL POWER PLANT EFFICIENCY TURBINE THERMAL STRESS Surface and Mid metal temperature probes in Casing : 55 % (TM) 95 % (TS) Rotor Mid metal temperature calculation : TM = TS [ 1 – (0.692 e –t/T1 + 0.131 e –t/T2 + 0.177 e –t/T3) ] Where,

TS – Surface Temperature T1 – 2408.31 TM – Mid metal Temperature T2 – 457.08 t – Time in minutes T3 – 56.62 T1, T2, T3 are computed using rotor material thermo-dynamic properties and shaft dia. Margin Calculation: T = TS – TM

Thermal Stress T Margin = T permissible – T actual

PLANT = BOILER X THERMAL CYCLE X TURBINE INTERNAL X TURBINE MECHANICAL X GENERATOR (30-40%) (75-90%) (35-40%) (88-90%) (99%) (98-99%)

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T PERMISSIBLE T Upper Margin Operating point T ACTUAL 0 TM

Lower Margin T PERMISSIBLE TURBINE OIL SYSTEM Gov. Rack Shut-Off valve LPBP Signal Oil Lub Oil (Brg.- 1 to 6) MOT Barring Gear Jacking Oil (Brg.- 1 to 6)

M A I N

H E A D E R

MOP

CONTROL OIL HEADER

COOLER

MAIN OIL

TANK

AOP

EOP

JOP

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TG Oil Pumps Start Criteria : 1. Lub oil pr. < 7.0 ksc A.O.P – 1 starts 2. Lub oil pr. < 6.5 ksc A.O.P – 2 starts 3. Lub oil pr. < 2.2 ksc E.O.P starts 4. Jacking oil pr. < 90 ksc Stand-by J.O.P starts BOILER FEED PUMP

Start permissives : 1. De-aerator level adequate ( 700 mm ) 2. Bearing temperature normal ( < 60 C ) 3. Lub oil pressure normal ( 2 kg / cm2 ) 4. Suction valve full open. 5. Booster pump suction pressure adequate ( > 3 kg / cm2 ) 6. Cooling water pressure adequate ( 2.5 kg / cm2 ) 7. Re-circulation valve 100% open. 8. Scoop position is minimum.

Protections : 1. Bearing temperature high ( > 85 C for pump & > 90 C for motor ) 2. De-aerator level lo – lo ( < -230 mm ) 3. Lub oil pressure low ( < 1 kg / cm2 for 5 secs) 4. Discharge flow high ( > 430 T / Hr for 20 secs) 5. Working oil temp high ( > 130 C ) 6. Suction pressure low ( < 9 ksc for 30 secs) CONDENSATE EXTRACTION PUMP Protection & Interlock: 1. Hotwell level very low. 2. Discharge pressure < 14 ksc. 3. Electrical protection. 4. Auto starting of stand-by pump from discharge header pressure < 16 ksc.

ACW PUMP

Protection & Interlock:

1. Both pumps trip from tank level lo-lo. 2. Auto starting of stand-by pump when running pump trips. 3. Auto starting of stand-by pump when discharge header pressure < 3 ksc.

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ARCW PUMP Protection & Interlock:

1. Auto starting of stand-by pump when running pump trips. 2. Auto starting of stand-by pump when discharge header pressure is low. GENERATOR SPECIFICATIONS

Rated parameters : 1. Max continuous MVA rating : 247 MVA 2. Max continuous MW rating : 210 MW 3. Rated terminal voltage : 15.75 kV 4. Rated stator current : 8625 Amps 5. Rated power factor : 0.85 Lag 6. Excitation current at MCR condition : 2600 Amps 7. Slip ring voltage at MCR condition : 310 V 8. Excitation current at no load : 907 amps 9. Slip ring voltage at no load : 102 V 10. Rated speed : 3000 rpm 11. Rated frequency : 50 Hz 12. Efficiency at MCR condition : 98.47 % 13. Direction of rotation as viewed from slip ring : Clockwise 14. Phase connection : Double star CAPABILITY CURVE

MW Turbine Limit Thermal Limit

Stability Limit Rotor Current = Load Angle = Phase Angle Stator Current

MVAR

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Excitation System Excitation Power 0.7 – 0.8 % 1.6 MW BUS-I 400 KV BUS-II (1½ Breaker Scheme)

GT

Tie X’r Excitation X’r SCR 15.75 kV/575V AC (Station DB) Field Breaker Field Flasher DC

(DCDB) Arrangement of Thyristors in a single bridge :

3 AC Input Field Winding ROTOR DC Output

G

AVR

19

VDC = 1.35 VAC cos ‘’ is the firing angle of thyristor. It is usually between 5 – 30 .

Four such bridges are connected in parallel. Total field current is shared by all the four bridges. Each thyristor in every bridge is provided with the Snubber circuit which protects the thyristor from heating. Snubber Circuit of SCR

L Voltage surges are partially charged in the Capacitor ‘C’

thereby saving the SCR from high voltages. Also the Inductor ‘L’ limits the surge current to some extent.

Resistor ‘R1’ restricts the charging current of Capacitor. SCR R1 ‘R2’ is discharge resistor of Capacitor. C R2 Hydrogen gas cooling system

1. Generator gas volume : 56 m3 2. Nominal pressure of hydrogen : ( 3.5 kg / cm2 ) 3. Nominal temperature of Cold gas : 40 C 4. Purity of hydrogen : > 97 % 5. Relative humidity of hydrogen at nominal pressure : 60 % 6. Nominal temperature of cooling water inlet : 37 C 7. Nominal flow of cooling water : 350 m3 / hr 8. Hot gas temperature (alarm) : 75 C

Stator water cooling system

1. Nominal pressure at inlet to winding : 3.09 kg / cm2 2. Nominal temp. at inlet to winding : 40 C 3. Stator water flow : 27 m3 / hr 4. Stator water conductivity : < 5 mho / cm 5. Stator water expansion tank vaccum: 200 – 300 mm of Hg

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STATOR WATER PUMP Protection & Interlock:

1. Expansion Tank level low. 2. Auto starting of stand-by pump from stator water pressure < 2.8 ksc.

Seal oil system

1. Seal oil temperature after cooler : 20 – 40 C 2. Seal oil outlet temperature : 40 C 3. Differential pressure across duplex filter : 0.4 kg / cm2 4. Seal oil pressure at turbine & excitor

end : 5.9 kg / cm2

DC Seal oil pump starts when : 1. T.E seal oil pr. < 3.8 ksc 2. E.E seal oil pr. < 3.8 ksc 3. AC Seal oil pump discharge pr. < 4.5 ksc GENERATOR PROTECTIONS 1. Generator Differential (Relay – 87G ) 2. Stator Earth Fault

(i) Main Protection (Relay – 64G1) (ii) Stand By Protection (Relay – 64G2)

3. Rotor Earth Fault 4. Stator Inter – Turn Fault (Relay – 50G1) 5. Loss of Excitation / Pole Slipping (Relay – 40G ) 6. Negative Phase Sequence (Relay – 46G) 7. Low Forward Power (Relay – 32G1) 8. Reverse Power (Relay – 32G2 ) 9. Over-voltage (Relay – 59G ) 10. Local Breaker Back – up Protection 11. GT Over fluxing (Relay – 99GT) 12. Stator water flow low (< 13 m3 / hr) 13. Stator water conductivity high (> 20 mho / cm ) OFFSITE

CW PUMPS

Type : BHM-100 , Single Stage Motor HP : 950 KW Make : BHEL

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Capacity : 16,000 cu. m/hr Bowl Head : 16.36 mmwcl Speed : 420 rpm (Nominal) No. of Stage : One Max. Working pr. : 2 ksc Impeller Type : Mixed flow No. of Vanes : Four Max. Bearing Temp : 70 C BFV UNIT – 1 BFV UNIT – 2

BFV UNIT – 3 BFV INTERCONNECTION VALVES COMPRESSOR Discharge Pressure : 8 ksc Free Air Delivery : 25 . 68 cu. m/min No. of Cylinders : 4 Speed : 670 rpm

Protection 1. Air delivery temperature after intercooler high (> 48 C). 2. Lub oil pressure low ( < 1 ksc).

CW-1

CW-2

CW-3

CW-4

CW-5

CW-6

CW-7

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Air Drying Plant Exhaust to Atm. De-pressurise Inlet Outlet Re-pressurise From Atm.

Steps for ADP change-over :

1. Close exhaust valve. 2. Pressurize stand-by ADP. 3. Give ADP change-over command from panel. 4. De-pressurize. 5. Open exhaust valve. 6. Start blower. 7. Switch on the heater.

AD 1

AD2

HEATER

BLOWER-1

BLOWER-2

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DIESEL – GENERATOR Manufacturer : NGEF Excitation System : Brushless Engine BHP : 720 Stroke : 4 Rated Speed : 1500 RPM Cooling : Stationary water cooled D-G auto starting is from under-voltage in EMCC. 415 V 50 Hz EMCC Unit – 1 EMCC Unit – 2 EMCC Unit – 3 ADDITIONAL INFO ON OFFSITE EQUIPMENTS Capacity of some pumps :

1. L.P Fly Ash Water Pump : 450 m3/hr. 2. H.P Fly Ash Water Pump : 375 m3/hr. 3. Bottom Ash L.P Water Pump : 375 m3/hr. 4. Seal Water Pump : 90 m3/hr. 5. Fly Ash Slurry Pump : 600 m3/hr. 6. Fuel Oil Pump : 100 m3/hr.

Fuel Oil Tank

DG1

DG2

2826 M3

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OPERATION GUIDELINES OF MAJOR EQIPMENT

EHC related emergency situations and remedial actions Sl no

Emergency situation Observations Action to be taken

1 M/C is on EHC. Power supply failure in Pressure control rack/load control rack / transfer circuit rack leading to zero EHC output . Starting device will become off automatically due to EHC fault.

Load zero Machine on bar with ESV & IV open (Turbine not tripped) EHC fault alarm ( Spd. contr. Active when Load contr. P.S.fails—spd. Ref. Can be increased)

Confirm HP/LP bypass opening, isolate EHC from governing rack and parallely reduce starting device position from UCB Reduce boiler firing to restrict rise in boiler pressure.

2 M/C is on EHC. Admission control rack power supply fails leading to zero EHC output. Starting device will become off automatically due to EHC fault.

Load zero Machine on bar with ESV & IV open (Turbine not tripped) EHC fault alarm Zero starting device feedback Zero speeder gear feedback.

Confirm HP/LP bypass opening, isolate EHC and parallely reduce starting device position from local Reduce boiler firing to restrict rise in boiler pressure..

3 M/C is on EHC pressure control mode and Throttle pressure set point becomes zero. EHC output will increase.

EHC output may go to 100%. Starting device will track to 100%, resulting wide opening of HP/IP control valves.

Tracking should be made off manually and starting device to be reduced manually to adust the load and pressure. EHC may be isolated.

4 M/C is on EHC, Tracking on and Strating device becomes inoperative due to motor failure/overload/ jamming.

During increase in boiler firing Boiler prassure will increase due to load restriction by starting device EHC output will go to 100%

Switch off the electrical module of starting device and increase starting device position from local so EHC can take control.

5 Starting Device gets continuous close command due to malfunctioning of command circuit. Hydraulic governing will take control,

Starting device position and Load will come down gradually Boiler pressure will

Try to switch off the electrical module immediately before stop valves closes. Increase starting device from local

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load will reduce gradually, ultimately stop valves will close and turbine will trip.

start increasing resulting in opening of HP/LP bypass.

so that EHC can take control. Parallely reduce boiler firing.

6 Speeder Gear gets continuous close command due to malfunctioning of command circuit. Ultimately complete unloading and generator motoring may take place.

Speeder gear position and Load will come down gradually Boiler pressure will start increasing resulting in opening of HP/LP bypass.

Try to switch off the electrical module immediately before stop valves closes. Increase Speeder gear from local so that EHC can take control. Parallely reduce boiler firing.

7 Trim device operated due to malfunctioning/power supply failure of solenoid

Trim device operated alarm IP control valves will get throttled in case of partial load operation.

reduce boiler firing to restrict rise in boiler pressure.

8 M/C is on EHC, power supply failure in CCA panels only.

All indication lamps in atrs console will go off. EHC output and Load will become zero due loss of GCB close feedback. All ATRS drives will become inoperative

Confirm HP/LP bypass opening, isolate EHC, Adjust starting device from local. Reduce boiler firing.

9 Unloading due to malfunctioning of TSE margin circuit.

TSE indicator will show abnormal margins and load will come down Speed controller will be active if load comes below 10%(block load)

10 Loss of speed signal

AOP & JOP will take auto start Lub oil pressure will come down in case of breakage of MOP shaft

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GENERATOR GAS PURGING AND FILLING PURGING OUT HYDROGEN BY CARBON DI OXIDE PREPARATION

1. Make arrangements for hot water, which will be required during CO2 charging. 2. Check for any leakages in CO2 manifold 3. Ensure sufficient number of CO2 cylinders 4. Inform fire fighting 5. Ensure availability of Flash Evaporator 6. Reduce barring gear speed or do hand barring if conditions permit. 7. Inform Chemistry Department about the program.

ACTIVITY:

1. Depressurise the generator casing by venting Hydrogen out to atmosphere slowly by following instructions /directions given at the gas valve manifold.

2. Bring down hydrogen pressure to 0.2 ksc 3. Set the valves to CO2 charging and HYDROGEN purging position and pressurise generator

casing to 0.4 ksc by CO2. 4. Purge out the gen casing gas mixture by maintaining 0.1 ksc gas pressure. 5. Do gas analysis after charging 15 cyliders. 6. Purge LLD lines, Gas Driers by CO2 for removing any entrapped Hydrogen. 7. Repeat gas analysis after charging every 5 nos of CO2 cylindrers or at suitable intervals . 8. After attaining about 80% CO2 purity put the barring gear in service for at full barring speed for

15minutes for removing any Hydrogen pockets inside casing. 9. Continue hydrogen purge out till aCO2 purity of 98% is achieved.

PURGING OUT CARBON DI OXIDE BY AIR PREPARATION

1. Ensure availability of dry compressed air . 2. Clean the air filter 3. Connect the air hose to the air inlet line.

ACTIVITY

1. Purge out CO2 by air. 2. Do gas analysis after at least 30 mins. of air purging.

PURGING OUT AIR BY CARBON DI OXIDE PREPARATION

1.Make arrangements for hot water, which will be required during CO2 charging. 2.Check for any leakages in CO2 manifold

27

3.Ensure sufficient number of CO2 cylinders 4.Inform fire fighting 5Ensure availability of Flash Evaporator 6.Reduce barring gear speed or do hand barring if conditions permit. 7.Inform Chemistry Department about the program.

ACTIVITY:

1. Depressurise the generator casing by venting Air out to atmosphere slowly by following instructions /directions given at the gas valve manifold. 2. Bring down Air pressure to 0.2 ksc 3. Set the valves to CO2 charging position and pressurise generator casing to 0.4 ksc by CO2. 4. Purge out the gen casing gas mixture by maintaining 0.1 ksc gas pressure. 5. Do gas analysis after charging 15 cyliders. 6. Purge LLD lines, Gas Driers by CO2 for removing any entrapped Air. 7. Repeat gas analysis after charging every 5 nos of CO2 cylindrers or at suitable intervals . 8. After attaining about 80% CO2 purity put the barring gear in service for at full barring speed for

15minutes for removing any Air pockets inside casing. 9. Continue Air purge out till aco2 purity of 98% is achieved.

PURGING OUT CARBON DI OXIDE BY HYDROGEN PREPARATION

1. Ensure availability of HYDROGEN Cylinders. 2. Ensure availability of NON SPARKING TOOLS.

ACTIVITY:

1. Bring down CO2pressure to 0.2 ksc 2. Set the valves to HYDROGEN charging and CO2 purging position and pressurise generator

casing to 0.4 ksc byHYDROGEN. 3. Purge out the gen casing gas mixture by maintaining 0.2 ksc gas pressure. 4. Do gas analysis after charging 15 cyliders. 5. Purge LLD lines, Gas Driers by HYDROGEN for removing any entrapped CO2. 6. Repeat gas analysis after charging every 10 nos of HYDROGEN cylindrers or at suitable intervals

. 7. After attaining about 80% HYDROGEN purity put the barring gear in service for at full barring

speed for 15minutes for removing any CO2 pockets inside casing. 8. Continue CO2purge out till a HYDROGEN purity of 98% is achieved. 9. After conferming HYDROGEN purity pressurise Gen.casing to 3.4 Ksc.

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COOLING PROCESS OF BOILER IN STAGE-1 & STAGE-2 After shutting down the boiler follow the steps to cool the Boiler. 1. Keep one set of ID & FD fan in service in cross path i.e. ID-A with FD-B or ID-B with FD-A. 2. In Stage-2 a) for both SAPH keep gas outlet damper closed while gas inlet & air inlet & outlet

dampers open. b)for both PAPH keep gas inlet & outlet and air inlet & outlet dampers open.

3. Depressurize the boiler to 10 kg/cm2 by keeping HP – LP bypass system charged then close MSV and open SH header drains.

4. Evacuate RH coils completely keeping only LP Bypass charged for a while. 5. Adjust Secondary air flow at around 30% of MCR. 6. Do not open manholes and do not break sealing of trough of boiler to prevent unaccountable air

ingress. 7. Control drum top bottom metal temperature difference within 50ºC. If the difference goes beyond

that regulate air flow and take FW to drum and drain through EBD. Keep CBD closed. 8. Open SH header vents and drum vents at 7 kg/cm2 and 2 kg/cm2 drum pressure respectively. 9. When drum metal temperature comes to <150ºC drain water wall through LPD. 10. After drum metal temperature comes to 120ºC sealing of trough may be drained and FD fan is to

be stopped. Keep ID fan running. 11. Record the parameters as given in the format.

Time

SAflow

APH gas I/L

temp

FW flow at

Eco I/L

FW temp at Eco O/L

Drum Metal Temperature Top/Bottom

Left Centre Right

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HP HEATER CHARGING PROCEDURE OF STAGE-1 UNITS A) CHARGING FROM WATER SIDE : 01: Open FW outlet drains and vents partially for venting and warming up. 02: Open the manual isolation valves before group bypass pneumatic valves FW 36 & 37 and

check instrument air supply

03: Open FW inlet and outlet valves of HPH 5 & 6 and close individual heater bypass valves.

04: Close all the shell side drains and vents including stand pipe drains & vents.

05: Open the isolating valves before and after emergency drip valve keeping watch on

condensor vaccum.

06: UNLOCK BOTH THE GROUP BYPASS VALVES . FW 35 FIRST THEN FW 34.

07: Open the HPH charging line valves slowly and watch water coming out of the vents and

drains

of the heaters. Close dump valve FW-73.

08: Close vents and drains after proper venting and warming up. Pressure gauge at HPH-6

outlet line

will show almost BFP discharge pressure.

09: Give INSERVICE command to group bypass valves.

10: Confirm full lift of spindle of both FW-34 & 35 from local.

11: Close HPH charging line isolating valve

12. B) CHARGING FROM STEAM SIDE:

13. 1: Ensure that heaters are charged from water side.

14. 2: Open the isolating valves of deaerator side drip and cascading drip of HPH- 6

3: Open the shell vents to condensor slowly keeping watch on condensor vacuum.

4: Ensure instrument air supply to all drip control valves.

5: Open ES-6A and 5A slowly and warm up shell side of the heater. Shell side pressure ,HP

heater

FW outlet temperature and drip temperature will start to increase..

6. After long shut down or maintenance of HPH, shell side is to be flushed. Keep Emergency

drip manual valves closed & shell drain(at minus metre) open. Keep watch on drip level and

vac. Normalise after clear water comes from shell drain.

30

7: After around 30 minutes of heating, open ES-6 and ES-5 slowly and observe drip level to

come

to normal value.

8: Observe HP heater outlet temperature to increase.

C: ISOLATION PROCEDURE OF HP HEATERS:

1. Open ES-6A and ES-5A

2. Close ES-6 and ES-5 slowly. Keep watch on drip level so that HP heaters do not get

bypassed from level protection. Observe increase of load.

3. Close ES-6A and ES-5A. Keep watch on vacuum.

4. Keep open manual isolating valve before dump valve FW-73 . Otherwise, open HP heater 6

outlet line drain valve to avoid frequent opening and closure of group by pass valve during

bypassing of HP heaters from feed water side.

5. Give BY PASS command to group by pass valve after 5 min. of closing of Extraction valves.

6. Confirm full closure of group bypass valve from local.

7. LOCK BOTH THE GROUP BYPASS VALVES.

8. Close isolating valves before and after the emergency , normal and cascading drip line.

9. Open shell side drains and vents. Keep watch on vacuum.

10. Ensure full closure of ES-5/5A,6/6A and depressurisation of shell side.

11. Open FW side drains and vents.

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CONDENSER BACK WASHING PROCEDURE OF STAGE-I UNITS

01: Ensure supply healthiness and availability of Electrical Operator in front of module of

CW valve 2 & 5.

02: Be prepared for manual operation of valve CW 2 & 5 in case of any emergency.

03: Reduce load to less than 120MW keeping watch on vac.

04: Keep both main ejector in service for safety.

05: Close air evacuation manual valve of pass A.

06: Rotate butter fly valve CW 2 by 90 without stopping. Confirm full rotation of the valve from

arrow indicator on the valve mounting.

NOTE: Butterfly valve CW2 must not be left at intermediate position. It must be brought to final

position by manual operation if stuck up midway.

07: Open air evacuation manual valve of pass A . Confirm condenser vacuum to regain to at least to

original value.

08: Close air evacuation manual valve of pass B.

09: Rotate butter fly valve CW 5 by 90 without stopping. Confirm full rotation of the valve from

arrow indicator on the valve mounting

NOTE: Butterfly valve CW5 must not be left at intermediate position. It must be brought to final

position by manual operation if stuck up midway .

10: Open air evacuation manual valve of pass A . Confirm condenser vacuum to regain to at least to

original value.

11: Stabilise vacuum and normalize load .

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CEP SUCTION STRAINER BACKWASHING PROCEDURE

1. Ensure the CEP is not running and SLC is Off.

2. Isolate the 6.6 KV breaker of the CEP.

3. KEEP THE DISCHARGE VALVE OPEN .

4. Close the suction valve.

5. Close the vacuum equalising valve.

6. Close the gland sealing inlet valves.

7. Open the strainer drain valve and watch whether air is sucking or water is draining.

8. If air is sucking then close the drain valve. Further tighten the suction & vacuum equalising valve

then repeat step 7.

9. After completion of draining, open the backwasing line valve very slowly and observe water

coming out gently from strainer drain. Continue backwashing for 2 to 3 minutes. DO NOT FULL

OPEN THE BACKWASING VALVE AS OVER PRESSURISATION MAY DAMAGE

SUCTION LINE FLANGE GASKET OF THE STRAINER.

CEP NORMALISATION AFTER BACKWASHING

1. Close the backwashing valve.

2. Close the strainer drain valve.

1. Open the gland sealing inlet valves.

2. Open the vacuum equalising valve wait for sometime.

3. Open the suction valve slowly to full open position.

4. Normalise the 6.6 KV breaker.

5. Check the availability and keep the discharge valve open.

6. After selecting the running pump switch ON the SLC.

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VACUUM PULLING IN STAGE-1 1. Ensure one CEP is running through main ejectors and GSC. 2. Ensure CW is following through condenser. (CW inlet/outlet valves are about 30%opened. condition. If valves are not in opened condition then in coordination with UCB-1 open the valves.

3. Line up one gland steam exhauster ( suction valve open and power supply on) 4. Main ejector and GSC drips are in lined up condition. 5. Ensure Vac breaker in opened condition. 6. Isolating valve before seal steam controller in closed condition and upstream drain to

atmosphere in opened condition. 7. Atmosphere drain of ejector steam header (below main ejector) is in opened condition and

ejector steam header drain to condenser closed condition. 8. Ensure manual isolating valves(CA-1,2 near condenser: CA-3,4 near main ejector) are in

opened condition 9. Open the isolating valve of ejector steam and gland steam at dearator floor. 10. Put into service one starting ejector and open warm up drain valve(as 87) of seal steam header. 11. Open the isolating valve before seal steam controller. 12. At about condenser pressure 600 mm Hg start seals steam exhauster and charge seal steam. Put

seal steam controller on auto, observe seal steam header pressure and close vacuum breaker. 13. At about condenser pressure 500mm Hg put main ejectors in service. 14. Line up the drain from atmosphere to condenser of seal steam line & ejector steam header at

5.5 mt. VACUUM KILLING IN STAGE-1

1. Close the MS stop valves at boiler end(MS-301/MS-302) 2. Depressurise MS line and RH line by opening HP-LP by pass. 3. Closes all the mal drains which were opened during unit shutdown and line up atmospheric

drains of MS/HRH strainer. 4. After closing HP-LP bypass watch MS pressure (digital). If it increases then manually tighten

the MS stop valves. 5. If it remains at 1 KSC then reduce vacuum by taking out ejectors. Wait for VAC dropping upto

500mm Hg. 6. When back pressure is about 500 mm Hg then close the seal steam control valve and close the

seal steam isolating valve at 5.5 mt. Keep open the VAC breaker. Open atmosphere drain of seal steam line and ejector steam line (At 2.5 mt).

7. Open the starting ejector air valves and watch the back pressure which should be less than 760mmHg.

8. Check from local whether steam is coming out from FAC breaker or not. 9. If steam is not coming out then close ejector & gland steam root valves at deaerator floor.

34

BFP ISOLATION STAGE-1

1. Ensure that pump is not running and lead/lag selection switch is in normal position.

2. Close the discharge valve and isolate the power supply.

3. Isolate the 6.6KV breaker.

4. Close recirculation valve at deaerator floor.

5. Close the suction valve slowly and watch local suction pressure.

6. If suction pressure increases then open the suction valve and manually further close the discharge

then repeat step-4 till suction pressure remains constant.

7. Open booster discharge vent valve.

8. Open booster pump suction drain and main pump discharge drain.

9. After completion of draining issue the PFW.

BFP NORMALISATION STAGE-1

1. Close the drain valves and keep open vent valves.

2. Crack open the suction valve, watch suction pressure and vent the system.

3. After proper venting close the vent valves.

4. Open the suction valve fulluy.

5. Open the recirulation valve at deaerator floor.

6. Normalise power supply of discharge vavle.

7. Normalise 6.6 KV breaker.

8. Check availability.

9. After Opening the discharge valve keep the selector switch in lead position.

35

CEP ISOLATION STAGE –1

10. Ensure the CEP is not running and SLC is Off.

11. Isolate the 6.6 KV breaker of the CEP.

12. Close the discharge valve and isolate power supply.

13. Close the suction valve.

14. Close the vacuum equalising valve.

15. Close the gland sealing inlet valves.

16. Open the strainer drain valve and watch whether air is sucking or water is draining.

17. If air is sucking then close the drain valve. Further tighten the suction & vacuum equalising valve

then repeat step 7.

18. After completion of draining issue PFW

CEP NORMALISATION STAGE –1

7. Close the strainer drain valve.

8. Open the gland sealing inlet valves.

9. Open the vacuum equalising valve wait for sometime.

10. Open the suction valve slowly to full open position.

11. Normalise the power supply of discharge valve and open it.

12. Normalise the 6.6 KV breaker.

13. Check the availability and kept open the discharge valve.

14. After selecting the running pump switch the SLC.