Preconditions:
- No. of ESP fields out of service >2 in the respective pass
- Continuously rap for at least 1 hour before FG side Isolation
- Evacuation of ESP Hoppers are to insured online as far as possible
- Status of Hopper Heaters are checked
- Defect list pertaining to the pass wrt ESP(CERM,EERM,Hopper Leakage, DLI etc) , Ash Handling system(Valve Opening Problem, Flange Leakages, Gasket Leakages, CT Leakages, Seal Box Leakage)
- Note Down the Current and Voltage of All Fields and fill the log-sheet
- Close Inlet & Outlet FG Damper of respective pass
- Switch off all Electrical Fields from CCR
- Stop rapping after 1 hour of continuous rapping
- Isolate Electrical fields and lock & Earthing done.
- FG outlet Dampers to be kept 10% Open and then Electrical Isolation of Inlet and Outlet Dampers is to be carried out
- Hopper Heater, shaft & Support Insulation Heater Power supply to be switched off
- Issue PTW to AHD
- AHD to open manhole, Observe ID Fan loading after manhole opening
- Now Pass is Completely Isolated and Cooling under Progress. Maintenance can be done
- All Hoppers are Empty
- Shut-off Vacuum checked with air intake valve closed, it should be >=300-350 mm Hg
- All air intake valve passing checked(if manhole was opened)through the manhole
- Check PTW is cancelled
- Normalize Power supply of Inlet & Outlet Dampers
- Open the Outlet Damper fully to check air tightness of Hopper manholes & Casing manholes
- Normalize Hopper Heater, shaft & Support Insulation Heater Power supply
- Charge all Fields
- Check Pass Evacuation System in service on Auto mode & all Hoppers mouths are clean monitored by vacuum drop(<line vacuum)
- Outlet Dampers are already Open
- Open the inlet Dampers one-by-one and allow the Flue gas to pass through the pass
- Monitor the Id fan outlet temperature of that side & Observe that is dropping
- After sometime, this temperature will increase again
- Normalize Rapping motors power supply and Put it on Auto mode
- Note Down the Current and Voltage of All Fields and fill the log-sheet & Compare
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