Mastodon Power plant and calculations: pumps/compressors/fans
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Showing posts with label pumps/compressors/fans. Show all posts

12-troubleshooting guide for Boiler Feed Pumps (BFP)


 

                           








                       12-troubleshooting guide for Boiler Feed Pumps

SL No.

Problem

Root cause

Remedy/Action to be taken

 

 

 

 

 

 

 

  

 

1

 

 

 

 

 

 

 

 

 

High bearing vibrations

 

What are the reasons for high bearing vibration in Boiler feed pump (BFP)

More clearance in bearing

Maintain bearing clearance within the limit as recommended by OEM

Contaminants/burs in oil

Replace the oil

Pump operation in re circulation mode for long time.

Operate the pump at the flow > 30% of rated capacity

Pump should not be operated more than 30 min in recirculation mode

Miss alignment for axial vibrations

Check & correct the alignment

Looseness in foundation bolt or coupling bolts for vertical vibrations

Tighten the bolts

Imbalance for horizontal vibrations

Check & conduct balancing test at OEM shop

Over load operation

Operate the Turbine at or within its maximum capacity

Looseness in impeller

Inspect the pump thoroughly & rectify the errors in impeller fitment

Malfunction of the vibration sensor

Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.

 

 

 

 

 

 

2

 

 

 

 

 

 

High bearing temperature (Journal)

 

What are the reasons for high bearing temperature in BFP?

Low lube oil level

Check for any leakages, if there arrest the leakages

Top up the oil.

High lube oil temperature

Check for cooling water flow, remove the blockages if any.

Over load operation

Operate the pump at or within rated flow

Less clearance in bearing

Maintain bearing clearance within the limit as recommended by OEM

Malfunction of the temperature sensor

Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.

 

 

 

 

    3

 

 

 

 

Cavitation/abnormal sound

 

What are the reasons for cavitation in Pumps?

Low suction pressure

Check the reason for low suction pressure & Normalise

High feed water temperature at pump’s suction

Reduce the steam flow to deaerator & maintain the suction temperature as pre-design pressure. If pump suction pressure is low, it may reach the vapour temperature leading into steam formation inn pump.

Low deaerator level

Normalise the deaerator flow by increasing make up water or process return condensate.

Low deaerator operating pressure

Increase & maintain the Deaerator pressure as per rated pressure

Low suction water

1.Check for suction valve throttling & increase the suction water flow

2.Check for clogging of pump strainer due to any foreign materials.

High flow

Reduce the flow & maintain as per OEM design.

 

 

 

 

 

 

    4

 

 

 

 

 

 

More Balance leak off pressure

 

What is the reason for more balance leak off pressure in BFP?

Worn out balance discs

Inspect & replace the discs

More clearance in balance & counter balance discs

Inspect & adjust the clearance as per OEM manual

More suction pressure

Maintain the suction pressure as per OEM recommended

Blocked balance leak off pressure impulse line

Check & clear the line

Read>>>Boiler feed pumps SOP

Higher pump discharge pressure

Maintain the discharge pressure as per OEM recommended

High discharge flow

Maintain the discharge flow as per OEM recommended

Faulty pressure gauge

Replace the pressure gauge

 

 

 

 

 

 

 

    5

 

 

 

 

 

Low Balance leak off pressure

 

What is the reason for less balance leak off pressure in BFP?

Less clearance in balance & counter balance discs

Inspect & adjust the clearance as per OEM manual

Improperly fitted balance discs

Inspect & adjust the clearance as per OEM manual

Low suction pressure

Check & increase the suction pressure

Low discharge pressure

Check & ensure the correct discharge pressure

Leakages in balance leak off line

Arrest the leakages

Faulty pressure gauge

Replace the pressure gauge

 

 

 

 

 

 

   6

 

 

 

 

 

 

Pump overheating

 

What is the reason for pump over heating?

High feed water temperature

Maintain the feed water temperature as per design

Operating the pump at higher flow

Optimise the discharge flow

Operating the pump at flow < 30% of rated

1.Increase the flow beyond 30%

2.Do not operate the pump with discharge valve closed for long time.

Low suction flow

Check the strainer & clean

Check the suction valve & ensure it’s open 100%

Cavitation

Ensure suction pressure & temperature are as per design

Bearing failure

Replace the bearing or maintain the clearance

Continuous operation of the pump

Follow pump change over schedule.

 Boiler feed pumps SOP

Internal rubbing due to improper thermal expansion

1.Ensure uniform expansion of pump.

 

2.Do not start pump as soon as hot water induced into it. Allow it for some times for uniform thermal expansion.

 

 

 

 

 

 

 

 

 

 

 

 

 

   7

 

 

 

 

 

 

 

 

 

 

 

 

 

Journal bearing failure

 

What is the reason for BFP pump bearing failure??




No lubrication

1.Ensure proper oil level.

2.Follow lubrication & lubricant replacement schedule.

Insufficient cooling & operation of the pump at higher bearing temperatures

1.Ensure bearing temperature is in the range of 50 to 70 deg C.

2.Ensure proper cooling water is flowing in & out of the bearing cooling jacket.

Operating the pump at lower speed for long time

Ensure the pump will be operated at speed >80% to ensure proper splitting of lubricant oil to bearing liners

Starting of the pump at lower speed

Always start the pump at speed reference > 50%

Ensure pump will attain its 50% speed (1500 rpm) in initial 10-12 seconds, this will protect the bearing from lack of lubrication at initial lower speed.

Frequent start & stop of the pump

Ensure pump will not be started or stopped frequently

Starting of the pump with discharge valve opened

Never start the pump with discharge valve open to avoid sudden jerk load to the pump, which not only damages the bearing even harms pumps internals, coupling & motor

Stopping of the pump with discharge valve opened

Never stop the pump with discharge valve open to avoid sudden jerk load to the pump, which not only damages the bearing even harms pumps internals, coupling & motor

Boiler feed pump SOP

 

 

 

    8

 

 

 

Insufficient discharge flow or pressure

 

What is the reason for low discharge or low discharge pressure from Boiler feed pump?

 

Pump is running on partial load or lesser speed

Increase the speed

Discharge valve throttled

Ensure 100% opening of the discharge valve

Suction valve throttled

Ensure 100% opening of the suction valve

Air lock

Ensure proper priming of the pump. Keep open drain/vent provided at suction strainer for 3 sec.

ARC (Automatic recirculation) valve stuck or passing

Servicing of the ARC valve

 

 

 

    9

 

 

Frequent tripping of pump during start up

 

Why does the pump trip during start up?

Discharge valve Open

Close the discharge valve & start the pump

Pump jam

1.Ensure proper lubrication

2.Ensure uniform thermal expansion

Electrical related problems

Check at Motor & Panel side and rectify the identified problems

  

 

 

 

  10

 

 

 

Excessive Noise & Vibration

 

What are the reasons for excessive noise & vibrations in pumps?

Cavitation in pump

Ensure suction pressure & temperatures are normal

 

Pump air lock

Ensure proper priming of the pump

Bearing damage/worn out

Inspect and replace if needed

Internal rubbing

Inspect & replace damaged internals

Pipe lines vibrations

Inspect supports & rectify if required

 

 

 

 

  11

 

 

 

 

Mechanical seal leakage/Gland leakage

 

What are the reasons for Mechanical seal failure in pumps?

Improper installation

Check & reinstall the seals

Seals parts damaged

Check the root cause & replace the damaged parts

Frequent start & stop of the pump

Ensure pump will not be started or stopped frequently

Worn out shaft sleeve

Replace the sleeve

Jerk loads on seals

Ensure discharge valve is closed before starting or stopping of the pump

 

 

 

 

  12

 

 

 

 

Pump consuming more power

 

What are the reasons for more power consumption by Boiler feed pumps?

Automatic Recirculation Valve (ARC) passing

Get done the overhauling of valve

Bearing friction

Maintain required clearance in bearing

Internal rubbing

Replace the worn-out parts

Lesser efficiency of coupling & motor

Replace the worn-out couplings

Verify motor load & efficiency

Higher flow

Ensure pump is delivering flow as per design

Lower pump efficiency

1-Check pump hydraulic power

2-Check fluid temperature & suction pressure and ensure both are as per design.

3-Ensure pump’s discharge pressure is as per design

 











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