Electrical Centrifugal pump

[Mohamed Miloudi]

Hi experts & engineers

I work in an Old oil facilities where old systems are used. Currently we are facing a challenge on running electrical Oil shipping pumps. Here's a summary of this issue:

The facility produces 12K BBLS of Oil per day through a 20'' shipping line to another terminal by Electrical centrifugal pumps with discharge pressure of 400 Psi. Due to problems on the shipping line, it is no longer supporting this pressure due to ageing. Instead we use a diesel pump with discharge pressure of 300 psi for safety reasons. My question is :

Is there a way to adjust the pressure of the electrical pump down to 300 Psi? Any ideas, previous experience ?

Kind Regards
Med

 

[LittleInch]

You're in the wrong forum. Try the pumps or pipeline forum.

But yes you can. You need to provide a lot more information though.

 

[Mohamed Miloudi]

Alright

I will repost it into the pumps or pipeline forum.

Thank you very much for guiding me

 

[LittleInch]

Actually I thought you had posted in the electrical forum.

All you need is a control valve to reduce pressure coming out of the pump. Very simple and straightforward.

Ie you can use a VFD to reduce pressure, but s control valve is easier and cheaper.

Or you can modify the impellor to produce less head.

Many ways to do this.

 

[georgeverghese]

We need to see the entire process control scheme for the electric motor pumping unit and that for the diesel engine pumping unit also.
You may need overpressure protection (instrumented trip and overpressure PSV) on the electric unit, in addition to some process control loop changes to make this happen. A VFD can pay out very quickly if the pump curve shows this to be so. So post the electric pump Q-h curve also

 

[shvet]

if you have no budget and have a spare impeller - trim the impeller to control pressure with some penalty in capacity

diameter reduction = (300/400)^0.5 = 0.866
capacity penalty =12*(300/400)^0.5 = 10.4k BBLS

if you have some budget you can experiment with a variable frequency drive with the same results
if no one cares about electricity bills add a spillback line back to the suction tank to control discharge pressure by capacity variation

 

[Mohamed Miloudi]

We need to see the entire process control scheme for the electric motor pumping unit and that for the diesel engine pumping unit also.
You may need overpressure protection (instrumented trip and overpressure PSV) on the electric unit, in addition to some process control loop changes to make this happen. A VFD can pay out very quickly if the pump curve shows this to be so. So post the electric pump Q-h curve also

Thank you very much

 

[Mohamed Miloudi]

Actually I thought you had posted in the electrical forum.

All you need is a control valve to reduce pressure coming out of the pump. Very simple and straightforward.

Ie you can use a VFD to reduce pressure, but s control valve is easier and cheaper.

Or you can modify the impellor to produce less head.

Many ways to do this.

Appreciate your answer. Tnx

 

[moon161]

Some possibilities are:
VFD to control pump RPM
Impeller trim to reduce head at same RPM
Pressure reducing valve. The pump affinity laws will show you how RPM or diameter reduction will change your pressure and flow from the original.

Affinity laws - Wikipedia

en.wikipedia.org

 

[pierreick]

Hi moon161,
Affinity law is about Head, not Pressure.
Hi Mohamed,
If your pump is equipped with a wheel (max diameter), the cheapest way will be to trim it.
Check the pump curves Head vs Flow for different wheel diameter
Pierre