How do you preserve the power plants equipments in long shutdown??

 

PLANT EQUIPMENTS LONG SHUTDOWN PRESERVATION METHODS
SL NO.	EQUIPMENT	PRESERVATION METHOD
A	MECHANICAL
1	Boiler	1-Wet preservation (If shutdown period is up to one month) Maintain pH: 10-10.5 Hydrazine concentration :> 200 ppm Note: Check water sample at various locations like steam drum, mud drum, super heater, economiser & Water wall tubes. Concentration should be same at all collection points 2-Dry Preservation (If shutdown period is more than one month)
2	Deaerator & Surge tanks	Wet preservation Maintain pH: 10-10.5 Hydrazine concentration :>200 ppm
3	Travelling grate (TG)	After cleaning, inspection & Maintenance, keep run TG at least 10-15 minutes on every 6-7 days to avoid shaft jam in bush/bearings
4	ESP	After cleaning & Inspection, close all the man hole doors air tight & keep lime trays at various locations to avoid moisture accumulation on internals
5	APH & Economiser	After cleaning & Inspection, close all man hole doors air tight & keep lime trays at various locations to avoid moisture accumulation on internals
6	Boiler fans	After cleaning & Inspection..close all man hole doors air tight Change the shaft orientation at every 10-15 days by rotating shaft manually to avoid shaft sagging/bending
7	Boiler feed pumps	Keep suction valve open Change the shaft orientation at every 10-15 days by rotating shaft manually to avoid shaft sagging/bending
8	Air Compressors	Operate Air compressors at least 10-15 minutes at every 7-8 days or else rotate the flywheel one complete rotation
9	Main & Auxiliary cooling water pump	Rotate the shaft on every 10-15 days to avoid impeller jam in wear ring
10	Steam Turbine	1-Turbine dehumidification by blowing hot air through Turbine HP suction to LP suction & ensure relative humidity in Turbine is <40% 2-Put turbine on barring gear for 20-30 minutes at every 6-7 days 3-Operate HP & LP valves from 0 to 100% at every 15 days 4-Operate ESV at every 15 days
11	Turbine lub oil system	Keep "ON" oil centrifuge at least twice in a week
12	Ash handling system	Ensure all ash handling & storage systems are clean to avoid rusting/corrosion
13	Fuel feeding system	Maintain fuel feeding system internals clean to avoid corrosion & rusting
B	E&I
1	Generator	Keep "ON" Generator space heaters for 8-10 hours if atmosphere temperature is very less (In rain & winter seasons)
2	Power Transformer	Charge transformers at least 6-8 hours at every week to avoid moisture formation in oil
3	VFD drives	Keep charged all VFD drives continuously  Note: Avoid interruption of power supply to VFDs
4	Batteries	Inspect battery voltages regularly (twice in a month)
5	UPS & AVR	Check Healthiness of redundancy systems regularly
6	Motors	1-Cover all motors terminals by polythene covers to avoid entry of rain water 2-For higher KW motor keep "ON" space heaters
7	MCC & PCC	Keep lime trays at MCC, PCC to avoid moisture formation
8	DCS	Ensure DCS healthiness regularly Note: If DCS kept OFF, inspect the panels regularly to ensure rats/lizards are not entering into the panels
C	WTP
1	RO plant	Preserve RO membranes with 2-3% SMBS or other chemical for 30-40 days. After that drain  the preserved water & perform membrane flushing on every 7-8 days
2	Cooling tower	If CT is not necessary in shutdown, drain the cooling tower ,clean the sumps & apply lime
3	Cat ion & Anion Resin	Maintain normal water level in vessels Replace the vessels water at every 10-15 days
D	SAFETY
1	Fuel yard & Fuel handling	Depute a particular person to have daily round to avoid fire incidents due to saturation of coal/bagasse or any other fuel
2	Fire fighting system	Conduct fire fighting pumps trial (especially Diesel fire fighter pump & Main fire fighter pump) to ensure healthiness
3	Plant fire alarm system	Check Healthiness of fire alarm systems  regularly