warm up line for pumps

[waseem2008]

Hi
I have been assigned to design a warm up line for pumps handling heavy oil. These are three pumps in parallel. Normally when one pump is out of service for schedule maintance the warm up line line will help to avoid suction line to freeze. any suggestions how to design these warm up line or if there are any standards for centrifugal pump for warm up line.

Thanks

 

[roker]

Hello,

When handling such fluids it is obvious that the lines are heat traced (steam or electrical) and insulated, secondly for handling the pump you are draining the lines (suction and discharge) to the first block valve.
If you are concerned despite the tracing you can install a small diameter by-pass from the discharge to the suction (bypassing the check valve in the discharge line), it will keep the line hot also when the pump is in stand by and you want it to be ready to start in any time.

(also dont forget always to ask your partners what was done in similar projects...)

regards,
roker

 

[atmengr]

I agree with roker. If you have not had success in keeping the pump and suction line hot a small bypass around the discharge check valve will do the trick. I would shoot for a flow that will flush the volume of the pump every minute or so. Be careful when sizing the warm-up line if you have erosive materials in the flow, since it might take a large pressure drop from the discharge pressure to the suction pressure. I have used overlayed orifices instead of having a 3/4" line that will hole through.

Remember to make provisions to isolate the pump away from it's bypass line when you need to take it down for maintenance.