Showing posts with label pumps/compressors/fans. Show all posts
Showing posts with label pumps/compressors/fans. Show all posts

Boiler Feed Pumps Design factors & Pump Capacity calculation

 

DESIGN DATA FOR BOILER FEED PUMS

 Design data from site:

 

Ø  Type of liquid handled and its maximum & minimum temperatures

Ø  Water qualities like pH & Hardness

Ø  Water Kinematic Viscosity (cst)

Ø  Specific gravity of water at operating temperature

Ø  Net positive suction head required (NPSHR)& available (NPSHA)

Ø  Boiler capacity & operating pressure

Ø  Maximum & operating blow down rate of Boiler

Ø  Height of Steam drum

Ø  Height of Deaerator (Water inlet source)

Ø  Pressure drop in Economiser

Ø  No.of valves used in feed water discharge line & corresponding pressure drop as per standard.

Ø  Maximum & minimum suction pressure available at pump suction

Ø  Type of cooling water & its maximum flow available for bearings cooling

 Pump Design Data:

Ø  Rated flow (M3/hr)

Ø  Rated head (meters)

Ø  Nominal speed & Effective speed (RPM) (NS > ES)

Ø  NPSHR (meter)

Ø  Pump & Motor efficiency

Ø  No.of stages of pump

Ø  Motor rating

Ø  Pump suction & discharge nozzles sizes

Ø  Vapour pressure (kg/cm2)

Ø  Pump’s shut off head (meter)

Ø  Pump minimum flow (25 to 30% depends on pump operating head & flow)

Ø  Cooling water pressure


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Other considerations:

Ø  Balance leak off water flow source (generally balance leak off water is diverted to Deaerator)

Ø  Pump Rotation direction (Clock wise viewed from drive end)

Ø  Cooling water flow rate (LPM)

Ø  Pump’s suction & discharge elements hydro. Test pressures

Ø  Material of constructions (MOC) of all pump internals

Ø  Type of coupling used between pump & motor shaft

Ø  Type of Shaft seal used (Mechanical seal)

Ø  Protections given for pump (Protections like, bearing vibration sensors, bearing temperature sensors, pressure relief valve for balance leak off line, phase sequence relay for direction of rotation, cooling water pressure, pump over load etc)

Boiler feed pumps Questions & Answers

Calculate the boiler feed pump and motor size required for a boiler of capacity 90 TPH has steam drum working pressure 88 kg/cm2. The height of the drum is 35 meter from boiler feed pump Centre. And the suction water to pump is taken from Deaerator which is situated 15 meter above the pump centre.

Given that,

Boiler capacity: 90 TPH = 90 M3/hr

Steam drum operating pressure = 88 kg/cm2

Steam drum height from pump centre = 35 meter

Height of Deaerator tank from pump centre =15 meter

Assumption:

Boiler blow down 1%

Deaerator operating level from floor: 2.5 meter

Pressure drop in Boiler economizer: 2.5 kg/cm2

Pressure drop in feed water control station: 5 kg/cm2

Pressure drop in line, gate and globe valves and bends of feed water line: 5 Kg/cm2

Pump operating temperature: 110 °C

Economizer out let feed water temperature: 275 °C

Pump and motor efficiency: 65% and 95% respectively.

Total required discharge head for pump = (Drum operating pressure + Drum height (m) + Economiser pressure drop + Control valve pressure drop + Pressure drop in line, gate and globe valves and bends) X 1.10 (Take 10–15% extra margin)

= (88 kg/cm2 + 35 meter + 2.5 kg/cm2 + 5 kg/cm2 + 5 kg/cm2) X 1.1

Convert all the pressure head into gravity head in meter from formula P = Density X g X H…by taking the densities of fluids (water) at operating temperatures.

 P = Desnity X g X H

       

Then, we have,

Total discharge head = (1248 m + 35 m + 33 m + 52.5 m + 52.5 m) X 1.1 = 1563 meter

Pump rated flow = (Boiler MCR + Blow down %) X 1.25 (Take 25–30% extra margin)

                           = (90 + (90 X 1/100)) X 1.25

                    = 113.625= 115 M3/hr

The Capacity of flow seems more, it is better to consider 3 pumps 2 running & 1 stand by

Case-I:

Select 2 Nos of pumps 1 working & 1 standby (1W+1S)

For motor power, we have

Pump hydraulic power Ph = (Flow (m3/sec.) X Total head (Hd - Hs) X g (m/sec2) X density of feed water at 110 °C)/1000

                                          = 0.0319 X (1563 - 15 - 2.5) X 9.81 X 951/1000

                                          = 459.94 KW

Pump shaft power Ps = Pump hydraulic power X 100/Pump efficiency

                                   = 459.94 X 100/65 = 707.60 KW

Motor input power = (Pump shaft power X 100/Motor efficiency) X 1.10

                       = (707.60 X 100/95) X 1.10

                       =819.32 KW

From motor selection chart select Standard sized motor that is 825 KW

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Case-II

Select 3 Nos of pumps, 2 Working & 1 stand by (2W+1S)

Then, capacity of the one pump = 115/2 = 57.5 M3/hr (May take 58 m3/hr round figure)

For motor power, we have

Pump hydraulic power Ph = (Flow (m3/sec.) X Total head (Hd - Hs) X g (m/sec2) X density of feed water at 110 °C)/1000

                                    = 0.01611 X (1563 - 15 - 2.5) X 9.81 X 951/1000

                                    = 232.28 KW

Pump shaft power Ps = Pump hydraulic power X 100/Pump efficiency

                             = 232.28 X 100/65 = 357.35 KW

Motor input power = (Pump shaft power X 100/Motor efficiency) X 1.10

                       = (357.35 X 100/95) X 1.10

                       = 376.16 KW

From motor selection chart select Standard sized motor that is 375 KW


Factors Considered for Boiler Engineering

Comparing Case-1 & II

Total Installation capacity of Boiler feed pumps for case-1 = 825 X 2 = 1650 KW

Total Operation power = 825 X 85% = 701.25 KW

 

Total Installation capacity of Boiler feed pumps for case-II = 375 X 3 = 1125 KW

Total Operation power = 375 X 2 X 85% = 637.5 KW

 

In view of energy conservation considering Case-II is feasible. But in view of installation & maintenance cost Case-I is feasible.

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33-most frequently asked questions & answers on air compressors


1-What are the functions of air compressors in power plants?
The functions of the compressor is to take a definite quantity of fluid (air or gas) & deliver it at a required pressure
2-What are the applications of compressed/pressurized air in power plants?
Operating the control valves
Operating the solenoid valves
Operating the dome valves in ash handling system
Air dampers operation in fans
Operating pneumatic tools
3-How does air compressor work? & what are the effects of compression on air?
An air compressor takes in atmospheric air. Compresses it and delivers this air to a storage vessel from which it will be conveyed by the pipe line to the required equipments.
Effects of compression:
Air pressure & temperature increases & moisture content in air increases
4-What are the various types of air compressors used in power plants?
Generally reciprocating, screw & centrifugal air compressors are used.
5-How does the positive displacement compressors work?
These compressors work by increasing the pressure of the air by reducing its volume
5-How does the centrifugal compressors work?
Centrifugal compressors initially increase the air velocity & then pressure at compressor outlet.
6-What are the various types of reciprocating compressors?

  • Single stage & multi stage
  • Single cylinder & multi cylinder
  • Air cooled & water cooled
  • Lubricated & Non lubricated
7-What are single acting compressors?
It is a compressor that has one discharge per revolution of crankshaft.
8-What are double acting compressors?
Compressor that completes two discharge strokes per revolutions of crankshaft
9-What do you mean by compression ratio in compressors?
It is the ratio of volume of air before compression to the volume of air after compression.
10-What do you mean by air compressor capacity?
It is the quantity of air actually delivered by a compressor in m3/minute or m3/sec.
11-What do you mean by Free Air delivery (FAD)?
It is the volume of air delivered by compressor under the compressor intake conditions like pressure &temperatures. FAD is not calculated on standard atmospheric conditions, it is measured in terms of CFM.It means that, amount of compressed air converted back to actual inlet air conditions.
12-What are the various parts of centrifugal compressors?
Impellers, Vanes, Volutes, Suction Eyes, Discharge lines, Diffuser Plates, Seals, Shaft, Casing
13-What do you mean by swept volume?
The volume displaced or swept by piston when it moves between two ends.
14-What do you mean by clearance volume?
 It is the difference between the total volume and the swept volume.
It is the space between the cylinder end and the piston to allow for wear & for easy movement. And also clearance is for valves reception.
Therefore clearance volume should be small as possible, but cannot be reduced to zero since, for mechanical reasons to avoid contact of moving parts in compressors.
15-Compressors efficiency
1. Volumetric efficiency:-
It is the ratio of actual volume of the FAD at standard atmospheric condition in one delivery stroke (Actual air intake) to the swept volume (theoretical air intake) by the piston during the stroke.
2. Isothermal efficiency:-
It is the ratio of isothermal work done to the actual work done
3. Volumetric efficiency:-
It is the ratio of free air delivered to the displacement of the compressor.
It is also defined as the effective swept volume to the swept volume
4. Mechanical efficiency:
It is the ratio of mechanical output to the mechanical input
Mechanical efficiency = Indicated horse power / Shaft horse power
16-Why do the compressors located at higher elevation consume more power as compared to those of lower elevation compressors?
As the altitude increases, air pressure goes on decrease; hence inlet pressure to the compressor decreases. For this compressor has to consume more power to provide required discharge pressure.
17-What is the relation between Relative humidity & moisture carrying capacity of air?
As the relative humidity (RH) increases, Moisture carrying capacity of the air increases
18-What are the reasons for reduction of volumetric efficiency of a reciprocating compressor?

  • Very high speed of compressor
  • Very large clearance volume
  • Obstruction in inlet valves
  • Malfunctioning of valves
  • Overheating of compressed air
  • Inertia effect of air in inlet pipe
19-Why the FAD is actually less than compressor displacement?
Because

  • The fluid resistance through air intake valve& valves prevent the cylinder being fully charged with air at atmospheric conditions.
  • Losses due to leakages
  • The high pressure air trapped in the clearance space, must expand to a pressure below the atmospheric pressure before the automatic suction valves open
20-What is the significance of inter coolers & after coolers in Heat exchangers?
Intercooler & after coolers are the shell & tube type heat exchangers in which hat is removed from air which has been compressed & its temperature has risen as a result of compression.
The cooler which is placed in between the stages are called Inter coolers & coolers are fitted after the last stage is called after coolers. Generally after coolers are used for removing the moisture from air by reducing its temperature.
21-How do you increase the isothermal efficiency of reciprocating compressors?
Isothermal efficiency can be increased by;
Water jacketing: where water is circulated around the LP & HP cylinders, which helps to cool the air
Inter-cooling: Intercoolers are fitted between the two stages to cool the air coming out from 1st stage. In inter coolers air temperature is maintained around atmospheric temperature.
Adding external fins for smaller compressors
22-Why do you prefer multistage compression rather than single stage?
Because;

  • Air can be cooled between interstages
  • For the same pressure & FAD, multi stage compressors consume less power
  • These are having good mechanical balance
  • The pressure & temperature range can be kept as per requirement. This results into reduced wear & tear & increased volumetric efficiency
  • However multistage compressors with coolers arrangement is more expensive than single stage compressor
23-A single stage reciprocating air compressor takes 1.5 M3/min of air at pressure 1.013 bar & 25 Deg C temperatures & delivers at 6 bar. Calculate the final air temperature
Solution:
Assume law of air compression pVn = Constant
That is pV 1.35 =Constant
P1 = 1.013 bar & T1 = 25 + 273 = 298 K
P2 = 6 bar
We have
T2 / T1 = (P2 / P1) (n-1) / n
T2 = 298 X (6/1.013) (1.35-1)/1.35
T2 =470.36 K
T2 = 470.36 – 273 = 197.36 Deg C
24-Suction pressure of a double stage air compressor is 350 mmwc & discharge pressure 6 kg/cm2 .Then calculate the 1st stage outlet pressure?
P1 = 350 mmwc = (1.03-350/1000) = 0.995 kg/cm2
P2 = √(P1 XP3) = √(0.995 X 6)
P2 = 2.44 kg/cm2
25-What do you mean by perfect cooling in compressors heat exchangers?
The condition, where the inlet temperature of air at each stage of multi-stage machine should be the same as it was at the first stage inlet is called perfect cooling.
26-Is volumetric efficiency of a compressor is less at higher delivery pressure?
Yes, at higher delivery pressure volumetric efficiency of any compressor is less & vice versa
27-What do you mean by loading & unloading in air compressors?
It is the two step control of delivery pressure, where compressor is loaded when there is air demand and unloaded when there is no demand.
During unloading air compressors consume lesser power, say 30 to 40% of full load. Positive displacement compressors consume less power & screw compressors more during unloading.
28-Does incorporating VFDs to reciprocating compressors save energy?
No...Compressors are required to run at full RPM, if run at lower RPM time required for loading will increase. So loading & unloading by using VFDs is not recommended for reciprocating compressors However sometimes it can be applied for centrifugal compressors.
29-Explain the process of loading & unloading in reciprocating air compressors?
In reciprocating air compressors, suction valves of compressors are fitted with un loader. Suction valves get forced open by actuating Solenoid valve (SOV) when discharge goes higher than requirement.
During loading: The SOV de-energies & the suction valves open & close as per the operation of flat springs fitted with SOVs.
During unloading: As the pressure increases more than set pressure, SOV on actuating air line opens to allow air to force open the suction valves. During compression stroke air discharges through already opened suction valves & pressure does not increase during suction stroke.
For 50% unloading 50% of suction valves get forced open & for 100% unloading all the suction valves get opened.
30- Explain the process of loading & unloading in screw air compressors?
Screw compressors are silent in operation & also consume very less power as compared to reciprocating compressors.
Unloading: When the demand of the air reduced, a device known as suction slide valve or suction throttle valve is activated. Then very less quantity of air is allowed to pass through it.
Loading: During loading, suction slide valve remains open 100%.
31- Explain the process of loading & unloading in centrifugal air compressors?
For controlling the discharge pressure of a centrifugal compressor, VFDs are installed. As the air consumption decreases, discharge pressure increases & motor speed decreases accordingly to maintain discharge header pressure.
Inlet guide vanes & Anti surge valves are also used for controlling speed.
Thumb rules on air compressors
Every 4 degree rise in inlet air temperature results in a higher energy consumption by 1%  to achieve equivalent power output
For every 250 mmWC pressure drop in increase across at the suction path will increase the power consumption of air compressor by 2%
An increase 5.5 deg C in the inlet air temperature to the second stage results in a 2% increase in the specific energy consumption.
A reduction in the delivery pressure of a compressor by 1 kg/cm2 would reduce the power consumption by 6-10%
32-What are the functions of air receiver tank?
Functions

  • Serves as air reservoir
  • Prevents frequent loading & unloading of air compressor
  • Separates moisture from air
33-What are the different types of air dryers used?
1. Refrigerent type
Adsorption type
a.Desiccant heat less drier
b.Desciccant type hot air drier

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Boiler feed pumps (BFP) questions & answers for interview


Boiler feed pumps (BFP) questions & answers for interview:



1-What is the function of Boiler feed pumps (BFP) in power plant?
Functions:
To supply the feed water to boilers
To conduct the Boiler hydraulic tests
To supply the desuperheating & attemperator water required for process steam lines & boilers respectively

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 2-What are the type of prime movers (drives) used for BFPs?
Prime movers:
  • LT drive (415 V)
  • HT drive (11 KV)
  • Turbo drive (Steam driven)
3-What are the auxiliaries associated with BFP?
BFP auxiliaries
  • Cooling water pump & lines
  • Lube oil system
  • ARC valve
  • Mechanical seal flushing system
  • Balance leak off line & its PRV
4-What are the various pipe lines connected to BFP?

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  • Suction pipe line
  • Discharge pipe line
  • Bearing cooling water lines
  • Jacket cooling water lines
  • Mechanical seal flushing line
  • ARC line (Minimum re circulation line)
  • Impulse lines for instrumentation measurements (Suction pressure, discharge pressure, Differential pressure, balance leak off pressure)
  • Balance leak off line

5-What is the size of suction strainer of a BFP
It is generally 30 to 40 mesh, that is 30 or 40 hole openings in 1 linear inch on strainer.
A SS 30 wire mesh is generally wrapped on SS mesh having hole openings around 3 to 4 mm
6-What are the different protection devices given for boiler feed pumps?
  • Pressure relief valve
  • Balance leak off line
  • Auto re circulation valve

7-What is the function minimum re circulation line or Automatic re circulation valve (ARC VALVE?)
Minimum re circulation line is provided mainly for centrifugal pump with constant speed drive based on the system and vendor information. There are two types of minimum continuous flow required by the pump (Stable and Thermal). Pump is designed to operate at the flow greater than this flow rate. If pump is operated at less flow than the minimum continuous stable flow, it will damage bearing and internals and may abnormal vibration occur. Below the minimum continuous thermal flow, temperature of fluid will rise at faster rate. To avoid these problems, minimum re circulation line is provided. If the demand of the fluid is decreased below minimum continuous flow, then the auto re circulation valve of the pump will open and maintains the required flow and if flow increased more than minimum flow then auto re circulation valve closes. Generally for higher head flow like 1500 meter head pump the minimum circulation will be 20–25% of total capacity.
8-What is the function of balance leak off line?

Balance leak off line is used to balance the centrifugal pump shaft from axial thrust. During centrifugal pump operation, especially in multistage centrifugal, suction side will have relatively very less pressure as compared to the discharge side. Because of this, there are lot of possibilities that impeller along with the shaft and bearing will be pushed from discharge end to suction end which is also known as axial thrust. Balance line is used to balance the centrifugal pump shaft from axial thrust. Due to the axial thrust, pump bearings and internals will get damaged. To nullify this effect, a tapping from discharge end (between balancing & counter balancing disc) is connected to a balancing drum.
33-Frequently asked QnA on air compressors
9-Why the balance leak off line water is not connected to suction line to save the pump hydraulic power instead of directing it into Deaerator?

Balance leak off water temperature is little bit higher than pump operating temperature which may lead cavitations if it mixes with suction water. For some pumps where there is no risk of cavitations, in such cases this line is connected to suction side of the pump.
10-What is the operating pressure of balance leak off line ?
It is just 0.5 to 1 kg/cm2 more than pump’s suction pressure
10a-What is the standard  gap maintained between balance & counter balance discs?
It is around 0.8 to 1.2mm

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11-What does it indicate if balance pressure is increasing gradually?
It indicates the wear out of balance or counter balance disc. That is gap or clearance between these two discs has increased
12-How do you calculate the maximum allowable balance leak off pressure?
Maximum allowable balance leak off pressure = 0.03X (Shut off pressure-Suction pressure)+ Suction pressure.
13-What is the velocity of water in the balance leak off line?
It should not exceed 5 m/sec on any account
14-Why the BFP discharge water & balance leak off temperature is slightly more than that of suction water temperature?
15-Due to the compression action of water inside the pump, the water pressure rises around 2 to 3 deg C more than the suction water. Water is an in compressible fluid
15-What do you mean by the shut off pressure in centrifugal pumps?
Shut-off head is a condition, when a centrifugal pump runs with discharge valve closed. It is the maximum head generated by a centrifugal pump with zero flow and relatively less power.
16-How do cavitations occur? What are the abnormal effects of cavitations?

 

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50-QUESTIONS & ANSWERS ON CENTRIFUGAL PUMPS
Pump cavitation occurs when the pressure in the pump inlet drops below the vapour pressure of the liquid. Vapour bubbles form at the inlet of the pump and are moved to the discharge of the pump where they collapse and make high sound and vibrations often taking small pieces of the pump with them.
Cavitation is often characterized by:
Loud noise often described as a grinding or “marbles” in the pump.
Loss of capacity (bubbles are now taking up space where liquid should be).
Pitting damage to parts as material is removed by the collapsing bubbles.

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17-What do you mean by NPSHA & NPSHR in BFPs?
NPSHA: Net positive suction head available is the absolute pressure at the suction port of the pump.

NPSHR: Net positive suction head required is the minimum pressure required at the suction port of the pump to prevent the pump from cavitations.
NPSHA should be always greater than NPSHR (NPSHA >  NPSHR)
18-What is the significance of NPSH in BFPS?
If BFPs do not have required NPSH, then there will be more chances for formation of cavitations.
How the pump speed is related to NPSH
NPSHR varies approximately with the square of pump speed.
NPSHR = N2
19-How do you calculate the NPSHA ?
NPSHA = Absolute pressure in
NPSHa = Ha +- HZ - Hf + Hv - Hvp
Where, Ha is the absolute pressure on the surface of the liquid in the supply tank.
HZ is vertical distance between the surface of the liquid in the supply tank and the center line of the pump.
Hf is friction losses in the suction piping.
Hv is Velocity head at the pump suction port.
Hvp Absolute vapour pressure of the liquid at the pumping temperature of the pump, it could lead to cavitations of pump.

Boiler Feed Pumps Design factors & Pump Capacity calculation

20-What is the significance of vortex breakers in pumps?
A vortex breaker is a device/arrangement in pumps to stop the formation of a vortex when a fluid (liquid or gas) enters into pump suction. The formation of vortices can entrain vapour in the liquid stream, leading to poor separation in process steps such as distillation or excessive pressure drop, or causing cavitations.
21-What are the reasons for Vortexing in pumps?
Vortexing can occur if any of the following conditions are present:
  • Low liquid levels.
  • Liquid level falling greater than 1 Meter/sec.
  • There is a large concentration of dissolved gases in the liquid.
  • High outlet velocities in pipes leaving vessels. Generally greater than 3 meters/sec.
  • Liquids near their vapour point.
  • High circulation caused by asymmetrical inlet or outlet conditions.
  • Inlet piping too close to the wall or bottom of the tank.


22-What are the protection interlocks given for BFPs.
Protection interlocks: That is BFP will trip/stop on following conditions
  • Low Deaerator level
  • High bearing vibrations
  • High bearing temperature
  • Low cooling water pressure
  • More differential pressure of suction strainer
  • High load
  • Higher balance leak off pressure
  • Low speed (<40% of rated speed)

23-Write down the BFP start permissive interlocks
  • Start permissive interlocks
  • Deaerator level normal
  • Bearing temperature normal
  • Bearings vibrations normal
  • Cooling water pressure normal
  • Motor bearing temperature, winding temperatures normal
  • Discharge valve close
  • Suction valve open
  • Suction pressure normal
  • Differential pressure normal
  • Arc Valve open
24-How do you start the BFP?
BFP start up  sequence
  • Ensure all the start permissive are healthy
  • Ensure no maintenance activities are going on BFP & pump is ready to start with all respect
  • Start the pump from DCS by giving >80% command to VFD
  • Observe the bearing temperature, vibration & speed ramp rate
  • Ensure pump has reached its 50% speed within 10-15 seconds
  • If all parameters (discharge pressure, bearing temperature & vibrations, motor current, winding temperatures etc) are normal
  • Then open the discharge valve slowly
  • After 100% opening of discharge valve rise the speed as per your requirement
  • Note: Ensure all the parameters are normal on every operation on BFP
25-Why it is not allowed to run the BFPS at speed lesser than 50% of rated speed?
For journal bearing BFPS at speed < 50%  the oil splash rings will not flash oil in bearings, leading to the damage to the bearings due to low lubricating oil.
26-What will happen if BFPs run in reverse direction?
If pump runs in reverse direction for more than 5 seconds, there will be the more chances of pumps to seize
27-How do you stop the BFP?
  • Pump stop sequences:
  • Reduce the pump speed slowly up to 60% of rated
  • Close the discharge valve
  • Shut down the pump
28-What is the recommended minimum head for BFP operation?
Should not be less than 10% of its rated head except in start-up & shutdown conditions?
29-What will happen if pump is started and stopped with discharge valve open?
  • Pump may trip due to sudden motor over load
  • Alignment may get disturb
  • Shaft coupling may damage
  • May harm to bearings of pumps and motor
  • Piping supports may get disturbed
  • Pump foundation fasteners may get loose
  • So it is always recommended to start and stop the pump with discharge valve close.


29-What are the reasons for pump to seize?
Following conditions can cause pump to seize:
  • No suction or less liquid flow to suction
  • Operating pump continuously at lesser NPSH
  • Reverse direction rotation of pump
  • Damaged strainer
  • Foreign materials in impellers
  • Uneven thermal expansion of pump internals
30-What is the recommended acceptable value for a BFP shaft run out?


It is around 0.03 mm (Max. 0.05 mm)

31-When should one can carry out alignment on BFP?

Why do the Boilers explode???

Alignment on BFP shall be done when the temperature of the pump is <50 Deg C or in atmospheric temperature.
32-Why do you use 2 dial gauges for axial alignment of BFP?



BFP has more axial float that is 8 to 9 mm without bearings & seal & 0.8 to 1 mm with bearings & seal, so in order to get accurate readings 2 dial gauges are used for angular alignment & 1 dial gauge for parallel alignment. Refer above figure

33-What are the shutdown preservation methods for BFP?

Shutdown preservation method
  • Depressurize the pump
  • Drain all the water
  • Fill the pump with 1:2 or 1:1  Glycol water mixture.
  • Rotate the pump shaft twice in a week
34-What is the recommended bearing temperature for BFPs?
It should be less than 75 deg C (Max 90 deg c)
35-What are the recommended bearing vibrations for BFPs?
It should be less than 3 mm/sec (Max 5 mm/sec)
36-What is the allowable leakage drops for BFP mechanical seal
15 drops/minute
37-What should be allowable the DP across strainer
0.1   to 0.3 kg/cm2 (1000 to 3000 mmwc)
38-What is the filter mesh size for BFP oil replacement
Mesh size is 30 micro meters
39-What preventive maintenance activities that you are going to carryout on BFPS?
Preventive maintenance activities:
  • Pump cleaning
  • Oil level checking & top up if required
  • Alignment correction
  • Suction strainer cleaning
  • Cooling water lines flushing
  • Foundation bolts tightness checking
40-What is the acceptable impeller & wear ring clearance in BFP




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