Centrifugal Pump efficiency
Centrifugal Pump efficiency
(OP)
We have a API std centrifugal pump installed in our plant with following details as given by vendor:-
Capacity-13.36 m3/hr
Total Head- 163.9 m
Speed-3550 rpm
Sp. Gravity-0.5370
Viscosity-0.1109 cp
Efficiency-24.5%
BHP-13.05 kw
Shut off- 182.25 m
My question:: Is it recommended to use this pump with above efficiency.
Currently we are facing high vibration problem, and we suspect some design problem. We have replaced power end, mechanical seal, but still have high vibrations in the pump.
Capacity-13.36 m3/hr
Total Head- 163.9 m
Speed-3550 rpm
Sp. Gravity-0.5370
Viscosity-0.1109 cp
Efficiency-24.5%
BHP-13.05 kw
Shut off- 182.25 m
My question:: Is it recommended to use this pump with above efficiency.
Currently we are facing high vibration problem, and we suspect some design problem. We have replaced power end, mechanical seal, but still have high vibrations in the pump.





RE: Centrifugal Pump efficiency
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
If BigInch is correct and you are running well away from BEP, then you have a reliability penalty in addition to the energy penalty. However, it is also possible that you have a pump that is designed with low efficiency even close to BEP. We have examples in many parts of our plant. Sundyne pumps are notoriously low efficiency. We have fully-lined slurry pumps in our FCC bottoms service that are inefficient. Because of their design, the efficiency cannot be increased by much. If this is a service where some other priority (non-clog, erosion resistance, compact size, etc.) is more important that energy efficiency, then you may have few options.
Johnny Pellin
RE: Centrifugal Pump efficiency
Capacity-13.36 m3/hr
Total Head- 163.9 m
Speed-3550 rpm
Sp. Gravity-0.5370
Viscosity-0.1109 cp
Efficiency-24.5%
BHP-13.05 kw
Shut off- 182.25 m
The question "Is it recommended to use this pump with above efficiency." doesn't seem to blame the pump, instead it questions the application. You are correct to suspect a design problem: with a system that uses that pump in the listed conditions.
What % of BEP are you running at, less than 40%?
What is the suction pressure and how does the pump handle it in terms of thrust?
Product temperature, vapor pressure, are either of these higher than the original design conditions?
Missing quite a few pieces of the puzzle but once we get them all, I still don't see them fitting together very well...
RE: Centrifugal Pump efficiency
When one thinks about it, it wouldn't be in any pump manufacturer's best interests to have e = 24.5% @ BEP.
In conclusion, then, without knowing or seeing anything otherwise, you probably have a multi-stage pump running well left of BEP. Or, so it would appear based on what I see.
Regards,
SNORGY.
RE: Centrifugal Pump efficiency
Regards,
SNORGY.
RE: Centrifugal Pump efficiency
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
Most slurry pumps won't be designed or built to API anyway.
Sorry about us (me) creating the misunderstanding.
Regards,
SNORGY.
RE: Centrifugal Pump efficiency
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
rmw
RE: Centrifugal Pump efficiency
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
Thanks all for your responses. Sorry for the late reply. Let me clarify your doubts.
1. This is a single stage centrifugal pump.
2. This is not a slurry pump. Pumping fluid is Butene. Pumping temperature is 60 deg C with vapour pressure as 7.813 bara.
3. BEP of this pump is 25.5% at flow rate 18.4 m3/hr. That implies the pump is running close to its BEP.
4. Suction pressure is 7 bar g. Discharge Pressure is 15.6 bar g.
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
""3. BEP of this pump is 25.5% at flow rate 18.4 m3/hr. That implies the pump is running close to its BEP.""
25% as BEP is not uncommon for pump of the low folw/ high head = low Ns type. Especially from Sundyne and also the PEP series by FindeR pompe.
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
RE: Centrifugal Pump efficiency
After looking at the numbers you have posted I wanted to ask whether sufficient NPSH is available to the pump. Was it designed to pump butene at 60 degC?
RE: Centrifugal Pump efficiency
Most often a long vertical can pump handles this service since the first stage can be sunk to whatever elevation below grade is needed to provide adequate NPSHA. It is not uncommon to see 20-30 stages on a condensate service.
If this is a single stage centrifugal at ground level, it owuld be wise to study the NPSH profile of the pump and the installation.
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
As most of us would know, vibration can caused by 100 and 1 things starting with mis-alignment -- and we still haven't been given any clear info to work from, well next year we might have the missng detail.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso
RE: Centrifugal Pump efficiency
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Centrifugal Pump efficiency
If NPSH margin is in fact O.K., then next I might consider wear ring clearances?? Light hydrocarbons are notoriously bad lubricants. Usually clearances are opened up somewhat to accomodate low lubricity; if that is the case here, would help explain operating off BEP.
It would be nice to have curves, technical data, pictures of the pump and installation, teardown/inspect report of the last repair before performing diagnosis on the patient.
Of course we want this; but as the saying goes, "people in Hell want ice water". Quit whining and shine your balls some more.