Boiler Feed Pump 92d5z

Boiler Feed Pump Basics & Its Construction

Boiler Feed Pump- Heart of the Power Plant. How to choose a pump for Power Plant.

SYSTEM HEAD It is the total head of a system against which a pump must operate. Total System Head= (Total static head from supplying level to discharge level+ Discharge pressure) – (Suction Pressure+ Friction losses+ Entrance & Exit losses)

BOILER FEED PUMPS ST-1 POWER - 3.5 MW CURRENT – 361 Amp SUPPLY – 6.6 KV, 3Φ, 50 Hz SPEED – 1485 RPM

BFP scheme Hydraulic coupling

Resilance coupling MOTOR

Main p/p Booster p/p

Motor speed-1485 rpm Booster p/p speed-1485 rpm Main p/p speed- 4750 rpm

BFP FW scheme Transfer line MP

BP MOTOR

strainer

R/C v/v To D/A

NRV

Suction v/v Discharge v/v

WHY Recirculation ? For minimum FW flow. To avoid churning BFP discharge header

180 kg

180 kg A

0 kg B

To D/A

100kg 181kg

BFP(stage-1) Specification No-3 nos(2X 50%) Main Pump-8 stage centrifugal Pump Type-Motor driven Motor-6.6 KV Motor speed -1485 rpm, 3500 KW. Booster Pump-single stage centrifugal

Main pump M/S Wier Make. Model-FK8D30. Eight stage horizontal centrifugal pump of the barrel casing design. The pump internals are designed as a cartridge, which can be easily removed for maintenance without disturbing the suction and discharge pipe work, or the alignment of the pump and the turbo coupling.

BFP MAJOR COMPONENTS

BOILER FEED PUMP CARTRIDGE Shaft Impellers Diffs Ring Sections Suction Guide Discharge Cover Bearing Housings Bearing Brackets Journal Bearing Thrust Bearing Mechanical Seals

Mechanical seal

P/p casing

Tungsten carbide (rotating)

Carbon steel(static)

O ring

P/p shaft

BFP Sealing system Mechanical seals are used in MP & BP Mechanical sealwater cooling used arrangement in main p/p Clarified for seal cooling Clarified water used for cooling of DM water

DM water running in closed ckt

Mechanical seal cooler

Cold DM cooling water

Clarified o/l Hot DM cooling water

Thrust balancing Balancing disc is provided in main p/p Balance leak off pr-16 ksc.

Balancing Drum. Due to differential pressures acting on the impeller the rotating assembly is subjected to axial thrusts. The balance drum located at the non-drive end is designed to keep these forces neutralised and only the residual thrust remains, which is taken up by thrust bearing. The main components of hydraulic balancing arrangement are the balance chamber machined in discharge cover, the balance drum secured to the shaft and balance drum bush fitted in the bore of discharge cover. The thrust caused by the suction pressure acting on the area inside the wear ring on inlet side of each impeller is overcome by much greater thrust caused by the discharge pressure acting on the equivalent area on the outlet side of each impeller. The resultant thrust is therefore towards drive end of pump. Thrust force varies with load on the pump but hydraulic balance arrangement will reduce its effect enabling residual thrust to be taken by fitting pads of thrust bearing.

BFP Bearing Arrangements Main p/p - DE side-journal bearing. - NDE side-journal & trust bearing. Booster p/p-p/p - DE side-journal bearing. - NDE side-journal & trust bearing. Hydraulic coupling - 10 bearings(4 thrust bearings, rest-journal bearings).

Journal bearing

Bearings Journal bearings

Lub oil

White metal liner(babbit metal) Thickness-0.5 mm

shaft

Flexible Coupling

Lub oil scheme MOP(connected to gear box) NRV

AOP motor

AOP

2 no lub oil cooler Raw water from ARCW discharge

Oil tank

Lub oil filter Return from bearing Booster p/p bearings

Oil header

Motor bearings

Main p/p brg

When BFP is in S/B condition motor driven AOP is in service (Cut in Pr-1.2 Ksc), for cooling of bearings, because S/B BFP’s suction v/v is always in open condition & feed water temp. coming from dearator is around 166 Deg C. So BFP metal & Brg. temp. should be always around 160 Deg C, which required cooling even BFP in S/B condition. AOP discharge pressure- 3 Ksc. When we give start command to BFP motor driven cut out in auto at 2.3 ksc pr(gear driven MOP will supply lub. oil to bearings . Lub Oil Used in BFP- Servo Prime 46

Meshes with HC gear

Main-Motor driven shaft

Meshes with LO and WO pump gear

Coupled with driven shaft

Auxiliary Lube oil pump Lube oil Working oil pump

Gear box Gear box & Hydraulic coupling

Resilance coupling MOTOR

Main p/p Booster p/p

Gear box 1

3

4

5

2 Lub oil p/p Working oil p/p 7 9 8 10

6

Lub oil tank

* Gear Ratio- 1: 3.3

Hydraulic coupling

Working oil scheme WC p/p

Working oil make up

Hydraulic coupling

Regulation control drain Cold working oil Hot working oil

LUB OIL TANK WOC

Cooling water From ARCW Working oil cooler(2 in number)

Lub Oil header

Lub Oil P/P

To all bearings

Gear Aux Lub oil P/P Motor

Motor

Coupling

Coupling Scoop Tube

Main Pump

Working Oil P/P Oil Regulating Chamber Variable speed thermo coupling Working oil cooler

Coupled with driven shaft

Auxiliary Lube oil pump Lube oil Working oil pump

Hydraulic Coupling in BFP

Hydraulic Coupling Oil Used- Servo Torque-10

Working oil & Hydraulic coupling  Hydraulic coupling used for regulaing BFP speed.  Hydraulic coupling is combination of pump & turbine  By changing scoop position we can control the Main p/p speed thus we can control the flow of main p/p

P/p

Shaft Connected To motor

Space filled up with oil

turbine

Driven shaft connected To main p/p Scoop tube scoop

Meshes with motor side gear

HYDRAULIC COUPLING

Connected to pump shaft

Turbine of Hydraulic Coupling: Coupled with main pump shaft

Hydraulic Coupling bearing Assembly

Slot to fit Scooptube

Motor cooling

2 cooling fans are provided at the both ends of motor Cooling air fans sucks cold air which cools motor stator /rotor Hot air is cooled by water in the cooler(2 no of cooler provided) Cooling water coming from Aux. Raw cooling water Motor cooler p/p(ARCW p/p)discharge header

Cooling water

Hot air

Cold air BCW v/v

To WO cooler

Motor rotor

Motor cooler

Motor stator

BFP MOTOR

Drain

End Cover

Cooler

Cooler

Tray

Tray

Drain

Stator Rotor

Bearing

Fan

Stator

Fan

Bearing

Siphon Drain

BFP motor cooler

Sealing system Mechanical seals are used in MP & BP Mechanical seal cooling arrangement in main Clarified water used for sealp/pcooling Clarified water used for cooling of DM water Mechanical seal cooler

DM water running in closed ckt Cold DM cooling water

Clarified o/l Hot DM cooling water

Mechanical seal

P/p casing

Tungsten carbide (rotating

Carbon steel(static)

O ring P/p shaft

Mechanical seal

BFP parameter UCB parameter

Normal value

BFP current 290-300amp BFP flow 340 ton/hr BFP(MP) discharge pr 180 kg D/A pr 6.5 ksc BFP suction temp 167 degree BFP suction strainer DP 0.07 Drum level +50 mm

Local parameter Lub oil pr 3 ksc Lub oil cooler in service Lub oil temp cooler I/l/O/L

normally one 60/40 degree

Local parameter

Normal value

Working oil pr

1.4 ksc

Working oil cooler in service Working oil temp cooler I/l/O/L

normally one 120/75 degree

Hydraulic coupling max bearing temp Motor air temp 50 degree Clarified water pr 3.5 ksc Balance leak off pr BP suction pr 8 kg MP suction pr 16 ksc

16 ksc

65 degree

BFP starting permissive D/A level normal>800 mm Suction v/v open R/C v/v open Bearing p/p& motor temp normal(<75 degree) Lub oil pr normal(>1.5 ksc) Cooling water pr normal>3 ksc Suction pr adequate

Protection       

P/p & motor bearing temp hi-hi(>85 degree) Hyd coupling oil temp Hi-Hi(>130 degree) Lub oil pr low-low(<0.8ksc) Main p/p suction pr low(<8 kg) BFP flow hi-hi(>430 ton/hr-1 minute time delay) EPB pressed Electrical protection

BFP Protections Sr. Parameters No.

Alarm Value

Trip Value / Remarks

1

Motor [DE/NDE] bearing temperature

75ºC

85ºC

2

Main pump [DE/NDE] bearing temperature

75ºC

85ºC

< 1.2 Ksc

< 0.8 Ksc (Time delay – 5 sec)

90ºC

> 130ºC

< 12 Ksc

< 8 Ksc

450 T/hr

450 T/hr (Time delay – 55 sec)

550 mm

400 mm

3

Lube oil pressure low

4

Working oil temp Hi-Hi

5

BFP running & Main pump suction pressure low

6

BFP Flow Hi-Hi

7

Deaerator level low-low

8

Emergency Push Button Pressed

BFP Isolations 1. Ensure that pump is in stopped condition. 2. Get the main motor breaker isolated ( Electrical isolation). 3. Close discharge valve and isolate its electrical supply . 4. Close the suction valve .Ensure there is no rise in suction press. 5. Open suction strainer, booster pump casing, discharge line and main pump casing drain valves. 6. Open the transfer line vent, booster pump vent. 7. Close the manual recirculation valve at deaerator level.

BFP Normalisations 1. Physically check that work is complete and all men and materials are removed from site. 2. Get the electrical supply of AOP normalised. 3. Ensure that one lube oil cooler and one working oil cooler are charged from oil and water side. 4. Check oil level ( It should be more than 50 %) Start AOP, observe lube oil pressure (It should be more than 2.5 ksc) and oil filter DP (It should be less than 0.5 ksc).Check return oil flow in all bearings. 5. Open motor cooling inlet/outlet valves .

BFP Normalisations 6. Ensure booster pump,transfer line & recirculation line vents open , Close all drains. (To avoid pressurisation of pump). 7. Charge clarified water to mech seal coolers and jacket cooling.

Ensure clarified water Pressure is more than 3

ksc . 8. Open manual recirculation valve at deaerator and ensure recirculation control valve is open. Also ensure air supply to recirculation control valve. 9. Crack open suction and observe the discharge through the vents. Close the vent valves after venting is over.

BFP Normalisations 10. Open suction valve fully and ensure the suction pressure is adequate. 11. Get the discharge valve and its integral by valves supply, BCW valve supply normalized . 12. Open its discharge valve from UCB, Ensure there is no reverse rotation of the pump. 13. Get the main motor electrically normalised.

BFP Lube Oil Filter Change Over. Two lube oil filters provided in BFP Main pump. 1. No charging line provided. 2. No venting provided in both lube oil filters. Lube oil filter chocked alarm provided in alarm fascia. (Lube oil filter chocked at DP > 0.5 Ksc) BFP tripping on lube oil pressure low-low at 0.8 Ksc, Time delay- 5 seconds.

Hydraulic Coupling Pointer, T shape bottom

Match Yellow Mark on Handle & Nut

Lube oil Filter-A in-service

For Lube oil filter change over moves the handle in this

Hydraulic Coupling Match Yellow Mark on Handle & Nut

Pointer, T shape bottom Lube oil Filter-B in-service

For Lube oil filter change over moves the handle in this

BFP Lube Oil Filter Change Over. During Changeover :Place the handle over nut by matching the Yellow Mark.(Half Yellow mark on Nut & Half Yellow mark on handle) Slowly rotates the change over handle (180 degree) so that the pointer (bottom part of T) provided in the nut always moves towards the Hydraulic coupling side. When pointer moves towards Hydraulic coupling- both filters remain in service in pointer mid position. When pointer moves opposite to Hydraulic coupling- both filters became out of service in pointer mid position. The pointer (bottom part of T) shows the Lube oil filter inservice. Observe the rise in DP of filter to be taken in service.

Drum level control DP control When BLI <20% low range CV i/s , drum level control is single element control it see only drum level) When BLI>20% it becomes 3-element control. steam flow, feed water flow& drum level) Hi range CV try to maintain drum level. (CV opening<100% ) BFP scoop try to maintain DP range CV Low

BFP

Drum FR S

DP Drum level controlled by 1) FRS CV 2)BFP

Drum level control(stage-I) Initially there was DP control Now there is two control 1)DP control 2)Scoop control

In Scoop control auxiliary power is saved ,as BFP draw less power

DP control If drum level increase CV throttle, DP increase(>4 KSC) BFP master DP set point is 4 ksc BFP master try to maintain 5 ksc DP BFP scoop will reduce

Scoop control Drum level is controlled directly by BFP scoop. FRS CV=100% open DP maintained zero When load <70% scoop control to DP control take place

BFP isolation/normalisation 1-Booster p/p strainer drain 2-Booster p/p casing vent 3-transfer line drain 4-transfer line vent 5-main p/p casing drain 6-discharge line drain 7-recirculation line drain