Effect of Oscillation on Variable-speed Pump Discharge

[123engr]

Good day All,

I have two variable-speed pumps designed to be operate in parallel arrangement and discharge into a common manifold which is connected to a departing pipeline. They have different source of supply.

Concern was raised on how to mitigate the effect of oscillations in the discharge due to speed changes that would occur at the pumps at different time. Please, i want to know how I can mitigate this problem while not affecting the pump operation.

Someone proposed a control valve at the discharge of the pumps.

Your advise is highly appreciated.



I am what I am by His grace

 

[Latexman]

What kind of pumps are they? Centrifugal, PD, what?

Good luck,
Latexman

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[gerhardl]

My try at an answer:
Oscillations can occur from several causes.

A) Most common is small amounts at low speed where checkvalves (or highpoints open to air) will give 'gulping' effect. Precaution: check correct amount according to pipeline diameter and pump capacity.
C) Wrong inlet and layout of feedstock and placement of checkvalves and outlet. Precaution:check layout, form and placement of pipelines and checkvalves to hinder one pump 'overruling' the other. Check speed and correct amount for smooth operation/startup and stop for both pumps.
D) Separat inlets or Y-formed inlet to tank is better than feedstock.
E) The capacity of the pump is dependding from pump caracteristic (speed) and back pressure. If everything above is OK I dont see what a regulating valve at this point should do.

Perhaps you should repost at pump engineering forum to get more varied answers.

 

[123engr]

They are centrifugal pumps.



I am what I am by His grace

 

[123engr]

Synchronization of the VFD pumps allow us to prevent oscillation on the discharge header/pipeline.



I am what I am by His grace