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
  • Stop Topmost Mill to reduce firing, Reduce o/p of fuel maser manually
  • Close HP Heaters 5B & 6B Extraction block valves, Drip also closes slowly
  • Boiler Pr increases momentarily then drops as FW Temp has reduced
  • Further Reduce o/p of fuel master, steam temperatures.(Ensure TFM & IP mode)
  • The load will drop automatically in TFM to maintain Pressure SP
  • Stop one more mill, reduce o/p of fuel master manually
  • Maintain Drum, Furnace Pressure, PA Header Pressure during transient
  • Now Load is around 350 MW with 4-5 mills
  • Reduce Pr SP to 100 ksc and reduce fuel master and 
  • 3 Feeders with Loading mill((>75%, 45 Tons) may not need oil support
  • Adjust HPBP to match existing Throttle Pressure, LPBP in auto
  • Transfer IP mode to LP mode, Reduce Load Ref further
  • Change-over UT to ST at 200 MW
  • Reduce firing in one of the three mills, take out that pulverizer before that take gun support for the Running mill (AB Elevation)
  • Close Extraction of LPH 2. 3 once load <100 MW
  • Transfer FRS 100% to FRS 30 %
  • Stop one CEP, Close PRDS supply from Unit
  • Maintain Hotwell, Deaerator level
  • Take HPBP and LPBP in manual and reduce Opening of HP/LP bypass
  • Stop bottom Pulveriser after cutting it to minimum
  • Bring BT to the horizontal position
  • Remove the oil guns, moment 4th corner gun stopped, Boiler will trip and Loss of all fuel flow alarm comes
  • MFT Tripped alarm comes, Both MFR relays REd lamp glows
  • Bring air flow to less than 40% by FD Fan blade pitch
  • Close HPBP, LPBP manually and Increase SP Higher than Existing Pressure
  • Purge the boiler, MFR got reset
  • Maintain air flow between 30% to 40%
  • After maintaining drum level, close FRS line, close MDBFP discharge valve
  •  Wait till BCW suction temp comes 93 then Stop BCW and then MDBFP

Comments

Post a Comment

Popular posts from this blog

HP & LP Bypass Operation and Protection

Image
HP & LP Bypass Operation and Protection Purpose Boiler operation independent of the turbine Minimum steam flow through SH & RH tubes during start-ups, low load operation & sudden unloading of unit Utilized or building up of steam parameters Avoiding the boiler trip on Reheat protection No steam flow through Boiler steam tubes will lead to starvation & thereby overheating and lead to premature failure of tubes  The capacity of HPLP bypass is 60% of full load turbine steam flow  Reheat Protection: RH protection (delay=10 sec) will act if TURBINE HP V/V & HPBP CLOSED [ either turbine HP stop v/v or HP CV in both HP line closed ] & [ both HP BP <2%]             OR TURBINE IP V/V & LP BP closed [ Either IP stop v/v or IP CV v/v in both IP line closed ] & [ Either LP BP stop v/v or LP BP C/V in both LP line is closed] OR   Generator ckt bkr open & [both HP BP closed OR both LP BP closed HPBP Oil Supply Unit Interlocks: Pum
Read more

Generator Air Tightness Test

Generator Air Tightness Test Period Of Test= 24 Hrs without a Break Air Pressure Drop (Allowed in 24 Hrs) : <=0.15 ksc Air Test Pressure = 3.5 ksc All LLDs Drain Closed. Ensure Seal Oil system in Operation Seal Oil DP >1.5 ksc AS Seal Oil Pr>4.5 ksc, start H2S Seal Oil system H2 Cooler Isolated PW in Winding is in filled condition, Winding Isolated. PW also kept Isolated. PW Tank at Atmospheric Pressure Ensure availability of  Instrument air and Bleed Out moisture from it by keeping it open till  Connect flexible air hose with the gas plant through the coupling and ensure no air leakage is there  The filling is to be done by opening the valves in the normal H2 filling line where as the valve from H2 rack side will remain closed. Once the air filling is commenced the test record data sheet   The air valve is to be opened full. While pressurising the LLD / Seal oil DP / Seal oil parameters are to be recorded as per the enclosed sheet. The generator casing i
Read more