7 replies to this topic

[farid.k]

Is there any requirement for the atmospheric tank inlet pressure? I don't see any problem if pump head over size and pressure inlet to the tank above atm even 5 barg. As long as goose neck or pvrv adequately to cater the tank inlet flowrate should be ok. Any comment?

[fallah]

Is there any requirement for the atmospheric tank inlet pressure? I don't see any problem if pump head over size and pressure inlet to the tank above atm even 5 barg. As long as goose neck or pvrv adequately to cater the tank inlet flowrate should be ok. Any comment?

 

farid.k,

 

The inlet pressure of the incoming pump discharge line to an atmospheric tank is always atmospheric pressure (plus static head of the liquid if the connection to the tank is below the liquid level) regardless of the relevant pump is accurately sized or oversized...in fact the pump will adjust itself to be operated per the conditions existed at downstream...
 

[Mahdi1980]

Farid,

 

Mr. Fallah said the complete answer. The discharge pressure of the pump will be adjusted concerning the tank pressure plus the friction loss of connected pipeline and fittings.

So, the discharge pressure and flow rate of the pump will be determined by interception of pressure curve of system and performance curve of the pump.

 

Mahdi

[farid.k]

Thank Mahdi.

For me, as long as Pvrv adequately size base on rated flow rate, it should OK.
I just want to reconfirm as client keep on asking why tank design pressure below than inlet pressure.

[danyelson]

The inlet pressure value at the inlet of the tank will consider also static head, if the inlet tank nozzle is located on the bottom part of the tank. In any case, is not a problem for the tank. Probably there is an existing pump or the distance between pump and tank is very high, resulting to high pressure drop (based also on fluid properties, e.g. viscosity).  Please take care about pump curve and corresponding pump efficiency for this case.

[cea]

If I get intent of your question correctly, I understand that you want to check adequacy of PVRV on tank. Please confirm my understanding.

 

Although all above replies have rightly pointed out the concern, let me put it very distinctly.

 

As Fallah said, pump will adjust itself to meet tank pressure & will not deliver at higher pressure. In short, pump will start delivering higher flow for corresponding head requirement than rated flow at estimated duty condition.

 

This will, in turn, see high "outbreathing flow" than estimated duty condition of pump.

 

Thus, it does matter for PVRV calculation, if pump head is over estimated.

[farid.k]

If I get intent of your question correctly, I understand that you want to check adequacy of PVRV on tank. Please confirm my understanding.

Although all above replies have rightly pointed out the concern, let me put it very distinctly.

As Fallah said, pump will adjust itself to meet tank pressure & will not deliver at higher pressure. In short, pump will start delivering higher flow for corresponding head requirement than rated flow at estimated duty condition.

This will, in turn, see high "outbreathing flow" than estimated duty condition of pump.

Thus, it does matter for PVRV calculation, if pump head is over estimated.

Thanks for the response

[farid.k]

The inlet pressure value at the inlet of the tank will consider also static head, if the inlet tank nozzle is located on the bottom part of the tank. In any case, is not a problem for the tank. Probably there is an existing pump or the distance between pump and tank is very high, resulting to high pressure drop (based also on fluid properties, e.g. viscosity). Please take care about pump curve and corresponding pump efficiency for this case.

Thanks for the point highlight