Pulsation Dampeners on Recip Pumps: Bladder Type vs. No Bladder

[KernOily]

Hi guys. Looking for experience on pulsation dampeners in reciprocating pump service, on suction and discharge. Interested in what your experience has been in regard to which type of dampener is more effective in general at reducing pulsation in the suction and discharge piping.

I'm interested in comparing the dampener that has an elastomeric bladder charged with nitrogen (example: Status Flow or Pulsation Equipment) vs. the no-bladder "resonator" type (example: CoorsTek or Hydril).

I understand the maintenance requirements of the bladder; that's not a consideration here. I'm looking for experience that says something like "yeah, we tried them both and we found that the bladder-type dampeners are a lot more effective at reducing pulsation in the suction and/or discharge piping".

The pumps in question are 300 hp quintuplex in BFW service, if that matters.

Thanks very much! Pete

 

[georgeverghese]

Selection may be tricky on pump suction, as it probably is in this application taking feed from a de aerator operating at near to atmospheric pressure. But either should work alright on the discharge if dampener volume is adequate.

On pump suction, would suggest minimising dependance on pulsation attenuation devices. How about installing a low head NPSH booster pump that get you up to say 20-30psi more on discharge with about 30% more flow than the recip pumps downstream. Fit a bladder type dampener on discharge and a constant flow ( which is just in excess of this pump's min flow recycle requirement) recycle back to the de aerator.

 

[SB1976]

Based on personal experiences in Oil and Gas projects in Middle East region, the pulsation dampeners are usually as below :

For dosing (metering) applications --> gas charged type
For non-metering duty --> maintenance free bladder less type

 

[KernOily]

Thanks guys. Input much appreciated!
Pete

 

[georgeverghese]

Take a look at some other threads on this website. There are folks using a booster pump set to feed the main HP BFW pumps for de aerator applications, not pulsation dampeners.

 

[Andrew ONeill]

I have experience in the world of slurries. Typically, air filled / no bladder is what is used. I haven't been exposed to the "resonator" type ones.
For no bladder / air filled, you will require an air source to continually supply a bladderless accumulator, as the air does mix with the fluid.
They have problems in how to measure, the fluid level so that the air pocket is maintained correctly.
Also from experience, whatever the manufacturer spec's is typically woefully undersized when dealing with larger pumps (1 MW range piston pumps)
In the land of air filled / bladder type accumulators, bigger = less pulsation, units of the same physical size / pressure will provide similar results. Not sure on the resonator type ones.

Lastly just guessing, I assume the resonator type ones are tuned for a specific frequency, if using a variable speed drive you might want to ask some questions.

Andrew O'Neill
Specialist Mechanical Engineer
Australia

 

[KernOily]

Thanks Andrew. I appreciate the great information. Unfortunately, since this is boiler feedwater I have to keep out oxygen so that precludes the use of air-filled / no bladder. Thanks! Pete

 

[LittleInch]

You could use Nitrogen?

Or is any gas permeation not allowed?

The piping design and its supports or flexibility I believe has a much bigger impact on the pulsation dampening than the choice of damper.

A quin pump set should be reasonably stable output, but might have a higher frequency.

This sort of stuff can get esoteric pretty fast and really needs vendor input and piping design software to analyse your system with your pump and your pressures. What works for someone else is only a small part of the equation.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KernOily]

Thanks LI. N2 would be fine. To retrofit with that type of dampener now would be a significant expense (cost of dampeners plus piping changes) because the existing dampeners are the bladder-less type. I would need to make the case that those would be more effective than what is existing. That's why I'm looking for specific experience.