Calculations for Destaging a vertical pump
Calculations for Destaging a vertical pump
(OP)
Hello Everyone,
We have a 6 stage vertical pump developing a flow of 720 m3/hr at a head of 322m. The pump is of a 5 equal stage single suction impeller and first stage of double suction impeller.
Now we decided to destage the pump to reduce the power consumption. The only information I have are the pump curves.
Is there any possible way to calculate the effect of destaging a single stage on the head developed by the pump ?
Any help would be well appreciated.
Thank you.
We have a 6 stage vertical pump developing a flow of 720 m3/hr at a head of 322m. The pump is of a 5 equal stage single suction impeller and first stage of double suction impeller.
Now we decided to destage the pump to reduce the power consumption. The only information I have are the pump curves.
Is there any possible way to calculate the effect of destaging a single stage on the head developed by the pump ?
Any help would be well appreciated.
Thank you.





RE: Calculations for Destaging a vertical pump
Without the system data it becomes guess work.
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: Calculations for Destaging a vertical pump
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: Calculations for Destaging a vertical pump
It all depends on whether the stages are all truly equal or not.
This only works if you don't change anything else (impellor diameter, rotational speed etc).
Be careful though that whoever is asking you to do this actually understands what is going on. If the pump is operating without any throttling or flow control, then removing a stage you will probably end up with less flow than you had before....
Far far easier to ask the pump vendor though. They will just put the same pump through their system and spit out a new pump curve in minutes.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Calculations for Destaging a vertical pump
Johnny Pellin
RE: Calculations for Destaging a vertical pump
RE: Calculations for Destaging a vertical pump
In other words, if you only pull out a stage and don't add to the column/lineshaft assembly, then your bottom stage will be higher off bottom of sump. Make sure the low liquid level is above minimum submergence level from the suction bell/case. You will find Min. Sub. data from the manufacturer.
RE: Calculations for Destaging a vertical pump
Walt
RE: Calculations for Destaging a vertical pump
If he removes a stage he will have roughly 600 m3/hr at 322 m (though with less flow the pressure drop should be less so it should move to the right on the curve a bit to higher flow). And the power should be 5/6 of the original.
If we slow the pump the head drops as the square and the flow linear with speed. So if the speed is lowered 15% we should get 612 m3/hr at 232m, if this on the system curve. My hunch is that he needs more head so the flow would be lower depending on the pump curve.
So which set of flow/head is actually in a desirable place on the system curve (and keeps the pump near BEP)?
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Calculations for Destaging a vertical pump
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: Calculations for Destaging a vertical pump
"how do you reduced the speed of a synchronous speed electric motor (assuming it is direct motor driven)?" A magnetic shaft coupling can reduce speed (flow and pressure are reduced) and save power. It may or may not be suitable for this application , especially if there is a head limitation.
www.fluxdrive.com
Walt
RE: Calculations for Destaging a vertical pump
BUT if you have high STATIC head and your system curve is flat, which is probably the case for multi-stage, then the final pressure could be as high as 300m, but your flow will be even lower (say 640).... hope you follow.
RE: Calculations for Destaging a vertical pump
Without proper data it's just wheel-spinning and until the OP graces us with their presence again, if in fact they do, it's point less surmising what the end result is likely to be.
Given a few pertinent facts, the answer is an easy exercise.
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: Calculations for Destaging a vertical pump