Inter pressure between the Booster and PD pumps

[BRyad]

Hello,

I'm trying to size a positive displacement pumps wich delivers 1200 m3/d of oily water to be re-injected into a well at 150 (Wellhead pressure is 150 barg), the oily water is from a seperator at 12m from the grade with an operating pressure of 1.2 bara, the PD pump is 300m (include all the friction losses) from the seperator and the suction line is 6". My questions are:

1- When I propose only a PD pump, the NPSHA estimated (included acceleration head) is negative more than -100m is it clear that a booster pump is necessary or else... I ask this question because thera are some vendor's how propose a PD pump with NPSHRequired of 5.5m and the installation of dumpners reduce the pulsation and a solution for my very low NPSHA.

2- If a Booster pump is sued, How to determine the inter pressure between the booster an PD pump, knowing that the booster pump is at 200m (included all the friction losses) from the seperator.

3- In PD process data sheet, should I indicate the NPSHA with the estimated acceleration or without.


Regards

 

[micalbrch]

1. I doubt that you have a NPSHA of more than -100 m.
NPSHR of 5.5 m sounds reasonable for a PD pump.

2. To size the booster pump you need the flow and the head. If you have a triplex PD pump, the flow of the booster pump will have to min. 1.3 x flow of the PD pump. The head of the booster pump can be calculated as you have the flow and the pipe details.

3. One or the other. You must only mention "with acceleration head" or "without acceleration head".

 

[micalbrch]

Double Posting: See Pump Engineering Forum.

 

[atayto]

It is easy I think. Booster pump discharge pressure is usually a pressure which equals to NPSHr for PD pump at maximum flow and at PD pump suction. In some cases at design flow. In other words Booster should create pressure on PD pump suction which is equal to NPSHr for maximum/designed flow.