Designing injection system

[sujins]

I am designing the cryogenic liquid injection system and bring an old pump to use. The discharge line will be tied-in to the existing pipeline which have a flow control valve and orifice. I can not find the pressure drop of that control valve to include in the system pressure drop.(No specification sheet) My questions are that :

1. Can I use sizing program to find the pressure drop of that valve (I am not sure that the supposed Cv is right and also the result of the calculation? How can I know the exacted pressure drop? Please help.

2. When I calculate the required flow rate and head, it doesn't meet the Q-H curve of pump. So, I decide to use recycle line and controlled by pressure control valve to recycle some of flow rate back to suction source of pump. (I don't want to trim the impeller diameter)Should it be a good idea if not please give suggestion.

Many thanks in advance.

 

[Artisi]

1. contact the valve manufacturer for the Hl, guess or flow test the valve yourself for Hl if you consider it important.
2. Why not trim the impeller? why burn off good energy across a control valve - unless of course you have to handle varying flow conditions.


Naresuan University
Phitsanulok
Thailand