what is shape for Discharge Header of 3 centrifugal pumps in parallel? 1

[tangochem]

I have to connect three centrifugal pumps in Parallel.( two of which are of same characteristics while the other one is larger with greater discharge head and capacity).
Now what should the shape of the connections of discharge lines of these three pumps to the discharge header?

 

[SNORGY]

tangochem

There won't be one right answer to this.

If the pumps are moving hot fluid especially, you will need to look at the relative orientation and spacing between pumps and evaluate the thermal-expansion-induced forces and moments on the nozzles. That will probably govern the shape of the connected headers. Other than that, there will probably be a riser somewhere on the order of eight feet from each pump discharge nozzle, each connected to a common discharge header that can otherwise be made as straight as practical.

The larger pump may create some issues in your system by either forcing the other pumps left of BEP or, depending on the shape of the characteristic curves (especially if those of the smaller pumps are somewhat flat), backing them out completely. Not sure what you have for controls or if they are on VFDs, but you'll want to look at that. Note also that the combined characteristic will be especially flat, so you might want some kind of flow control on each unit.

Regards,

SNORGY.

 

[tangochem]

Thank you for your reply. I actually want to pump cold water. So will the attached image help me? It shows that the discharge header is vertical. The larger pump discharges straight up into the main discharge header and the other two smaller similar pumps meet the discharge header as shown in the image. Where as RPM are constant.

If i make the discharge header in horizontal direction and the nozzle of each pump discharges at right angle to the horizontal header then the flow of all the pumps will be divided into right and left directions and will make head on collision with one another. It will produce greater thrust and vibration. am i right?

Regards!

 

[pennpiper]

Tangochem,
Stop what you are doing and hire a trained and experienced "Piper".

 

[katmar]

There are two separate problems that you are facing. The first, which is the one pennpiper is warning you against, is the actual physical arrangement of the pipes to avoid vibration, ensure adequate support, allowance for expansion etc.

But there is a separate problem. You cannot simply put dissimilar pumps in parallel with each other. You may well find that if one of the smaller pumps is running at the same time as the larger pump then the smaller pump will not add to the overall flow rate at all. The smaller pump will be in danger of "churning" and overheating. You need to very carefully analize the pump curves to see if the pumps can operate together.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[SNORGY]

I think I touched on that also...in different words...

Regards,

SNORGY.

 

[katmar]

@SNORGY - Sorry, I obviously didn't read carefully enough. You had indeed covered this ground already.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[SNORGY]

@katmar - no worries; in fact, your words were easier to understand, equally correct, and a bit more to the point.

Regards,

SNORGY.