BOILER FEED PUMP PRE-CHECKS SAFE STARTING AND SHUT DOWN OF PUMP
In this article we discussed about the 210 MW power plant boiler feed pump operation . before starting the boiler feed pump what are the pre-checks of the pumps , local checks of the pump ,and also know about the safe running and shut down of the boiler feed pump . boiler feed pump is the heart of the boiler . boiler feed pump continuous supply the feed water to boiler for steam generation to avoid the water wall and super-heater from overheating .When all the feed pumps are in stopped condition and one feed pump is to be started carry out the following checks
Local checks of Boiler Feed Pump
1. No maintenance staff in working on the pump
2. All the control instruments and gauges are in proper place, all root valves for different gauges are in open condition
3. Cooling water for booster pump bearing cooling as well as gland sealing water supply is ok
4. Check availability of compressed air for penultimatically operated valves
5. Check that the Deaerators level is normal. Make local check and confirm by draining the gauge glass and recharging it.
6. Check that the oil level in lube oil tank is normal
7. Take the clearance from the electric department of auxiliary Lube oil pump. Confirm that it start and develop required lube oil pressure. Oil pressure of oil before journal bearing should be 0.8 to 1 kg/cm2 and 0.5 kg/cm2 before the thrust bearing. Check lube oil flow through drain line is normal.
8. Check that both lube oil and working oil coolers are charged from water as well as oil side.
9. Check lube oil level of booster pump is normal
10. Check power operated recirculation valve is closed and manual operated valve at Deaerators is open.
11. Check that manual valve at Deaerators on balancing chamber leak off line is open.
12. Check BFP discharge valve and it’s bypass valve is closed
13. Check that drain valves are closed
14. Charged the feed line after opening vents provide , up to feed regulating stations and then close all the vents.
15. Charged seal water cooler and stiffing box and LP cover cooling lInes
16. Charge feed pump motor cooler
17. Check scope tube is in minimum position
18. Check that the difference of temperature between pump body metal and feed water temperature is less than 30 degree C.
19. Take out EPB of main pump and give clearance to UCB for starting.
UCB ( unit control Board ) checks of Boiler Feed Pump
1. Insure that no PTW (Permit to work ) is pending
2. Check feed pump gauges in UCB ( unit control Board )are in proper working order
3. Check all remote operated valves have been given power supply and confirm their proper operation with local operator.
4. Check Deaerators level is normal
5. Check lube. Oil pressure is OK
6. check all the protection and interlock of the pump have been checked and are OK
7. check feed line has been properly line up
8. Check the valve indication open or close is in ok condition
9. Get the electrical supply for the pump
10. Check all the relay provided for the pump are reset
11. Check that the boiler requires feed water
12. Make a announcement for feed pump starting and ask local operator to be near pump.
START THE Boiler Feed Pump
1. check starting current and time
2. Check the recirculation valves opens and proper suction flow in maintained
3. Check electrically operated cooling water valve opens and cooling water flow is established
4. Check warm up valve has closed
5. Check auxiliary lube. Oil pump has stopped
6. Check feed pump vibration are normal
7. Check balancing leak off pressure is normal
8. Check bearing temperature of main pump, motor and hydraulic coupling bearings are normal
9. Check the lube oil drain flow again
10. Open the feed pump discharged valve and take the flow as per requirement in boiler
11. Check recirculation valve operation after sufficient discharge flow is maintained.
ROUTINE CHECKS OF BOILER FEED PUMP
1. For a pump which is continuous in service, check the following every hours
2. In no case bearing drain oil temperature should be above 70 degree Celsius
Check oil cooler inlet and outlet valves are open fully
Check whether adequate cooling water flow is there .if temperature is still going high inform UCB ( unit control Board )
3. Motor hot air cooler temperature- normal working temperature is around 60 degree Celsius. If it goes beyond this UCB ( unit control Board )(Release air lock in the water side of cooler through the vent cock) . If temperature goes beyond 75 – 80 stop the pump and check the cooler
4. Bearing oil pressure at LCB constant at 1.0 kg/cm2
5. Suction pressure around 10 kg/cm2 depending on Deaerators pressure but should not go below 6 kg/cm2 and should not be fluctuating too much.
6. Discharged pressure around 170 kg/cm2 for normal working. It should not also be fluctuating
7. Balancing pressure should be 3 to 4 kg/cm2 above suction pressure. In no case the difference of pressure between suction branch and balancing line should exceed 5 kg/cm2
8. Feed water flow through the pump at any instant should not be less than 200 T/hr. If it is less open the recirculation valve informing UCB ( unit control Board ) and see that the flow raises.
9. Feed water temperature at discharge of pump around 170 degree Celsius at normal working conditions
10. Bearing oil flow should be continuous without foaming at the sight glasses of individual bearings
11. Lubrication oil pressure before and after the filter , the difference should not be above 0.5 kg/cm2 . The discharge pressure for all the bearings of boiler feed pump and hydraulic coupling should be about 1.0 kg/cm2 excepting the thrust bearing for which it should be about 0.5 kg/cm2.
12. Check that the booster pump runs smoothly and there is no leakage of water from its glands. Check that there is continuous flow of gland cooling water maintained.
13. Bearing oil temperature of the booster pump should be checked for normal and should be within the limit.
14. Oil temperature at outlet of cooler around 85 degree Celsius .if the temperature is high check the adequate water is flowing through the cooler and if not inform UCB ( unit control Board ) .
15. Check for the oil level in the oil tank of the hydraulic coupling. It should be normal. If not proper grade of oil is to be topped up . If the level is falling continuous it indicating oil leakage in the system or oil seal failure of rotors bearings. Inform UCB immediately.
16. Check seal water temperature should be around 65 – 75 degree Celsius
17. the lube oil is to be tested for mechanical impurities acidity and moisture content at least once in a week or as per requirement.
18. See that the stand by feed pump is not idle for more than a fortnight
NORMAL SHUTDOWN OF BOILER FEED PUMP
1. open recirculation valve to avoided damage to mechanical seal and then closed the discharge valve of the pump to be stopped.
2. Gets scoop tube setting at minimum position
3. now switch off the boiler feed pump
4 Check that motor air cooler water side electrically operated valve closes automatically after stopping the pump. If not close it from UCB ( unit control Board )
5. check that auxiliary lubricating oil pump has started
6. Check that BFP ( Boiler Feed pump ) warm up line pneumatically operated valve has opened
7. However in case of extreme emergency feed pump can be stopped with discharge valve open.
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