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HOW VACUUM PULLING

HOW VACUUM PULLING

                                                    
HOW VACUUM PULLING

PRE START CHECKLIST OF VACUUM  PULLING

ü  IF THE TURBINE IS COMING AFTER A MAJOR OVERHAULING THEN GET CLEARANCE OF MAINTENANCE TEAM AND ENSURE CONDENSER JACK RELEASED.
üENSURE TG ON BARRING.
ü  AT LEAST ONE CW &3 CT FANS ARE IN SERVICES.
ü  CONDENSER IS CHARGED FROM COOLING WATERSIDE.
ü  HOT WELL LEVEL NORMAL
ü  ONE OF THE CEP IS RUNNING.
ü  AUXILIARY STEAM IS CHARGED WITH A PRESSURE OF 11 kg/cm2AT TEMP. 2500C. AND TURBINE GLAND SEALING PROCESS HAS BEEN COMPLETED.I.E. FG SEALING SYSTEM IS ON.
ü  VACUUM BREAKER VALVE IS IN CLOSE CONDITION.
ü  BOTH THE RUNNING EJECTOR ARE IN ISOLATED CONDITION, I.E.  SFG EJECTOR IN OFF CONDITION.
ü  AIRLINE MANUAL ISOLATION VALVES FROM CONDENSER FOR STARTING EJECTOR AND PRE SELECTED EJECTOR ARE OPENED.
ü  DRAIN LINES OF PRE SELECTED EJECTOR ARE THROUGH TO CONDENSER. 

             STEPS TO BE FOLLOWED:

1.      ENSURE NO PTW PENDING
2.      CONDUCT ALL THE PRE START CHECKS & RECTIFY THE NOT OK ONES ALONG WITH RESPECTIVE DEPARTMENT BEFORE PROCEEDING FURTHER.
3.      GIVE START COMMAND TO FG EVACUATION.
4.      IF START SEQUENCE IS IN PROGRESS FROM MAIN FG CONDENSER, THEN AUTO START COMMAND WILL BE TRIGGERED WITH THE COMPLETION OF FG SEALING SYSTEM.
5.      ENSURE THE MOTORISED VALE OF STEAM SIDE OPENS FIRST THEN MOTORISE VALVE FOR AIR SIDES OPENS FOR THE STARTING EJECTOR.
6.      WITH POINT NO 5, VACUUM  PULLING AUCTION STARTS.
7.      AS VACUUM INCREASES MORE THAN -700GM/CM2, OPEN HPBP AND START DUMPING STEAM(REF.NO. 20320400).
8.      KEEPING THE VACUUM IN RISING TREND AND SLOWLY INCREASES THE HPBP OPENING.
9.      AT HPBP OPENING OF 15%, THE FG EVACUATION WILL ACTIVATE THE START COMMAND FOR SFG EJECTOR.
10.  NOW THE PRESELECTED EJECTOR AIR MOTORISED VALVEOPENS FOLLOWED BY OPENING OF ITS STEAM VALVE.
11.  WITH THIS CONDITION, AT HPBP OPENING OF 17% THE CUT OFF OF STARING EJECTOR WILL OCCUR AND SFG EJECTOR WILL COMPLETE ITS ONE CYCLE.
12.  DURING CUT OFF OPERATION OF ANY EJECTOR ALWAYS ENSURE CLOSING OF AIRLINE VALVE FIRST THEN STEAM SIDE VALVE.
13.  COMPLETION OF STEP 11, COMPLETE THE FG EVACUATION CYCLE.
14.  WITH RUNNING EJECTOR IN SERVICE THE VACUUM STARTS RISING SLOWLY AND GET STABILIZED AT ITS PEAK VALUE.
15.  DURING THE ENTIRE PROCESS, KEEP A TRACK ON THE RISING TREND OF VACUUM, IF THE RATE IS NOT SATISFACTORY THEN CHECK
ü  FOR AIR INGRESS TO CONDENSER THROUGH DIFFERENT PATHS WHICH ARE CONNECTED DIRECTLY TO CONDENSER, LIKE FEED HEATERS, CEP, AND FLASH TANKS ETC.
IF CONDENSATE IS COMING OUT OF AIR VENT OR THE DRAIN LINE OF EJECTOR ARE COOL, THEN ISOLATE THE LINE TO CONDENSER AND MAKE THE DRAIN THROUGH TO ATMOSPHERE

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