Pipe sparger design

[akshey]

I am designing a straight pipe sparger. While going through the theoritical approach detailed in Perry hand book (page 6-32 to 6-34) I came to confusing point. It says that the net pressure loss in pipe (which includes the momentum pressure gain and friction pressure loss in the pipe) should be less than the orifice pressure drop.
I am not able to perceive how the pressure drop across orifice will affect the distribution in the pipe sparger.

Please help me understand this concept.

Thank you
Akshey

 

[Duwe6]

Think of the pressure-drop of each orifice as "backpressure". If the total backpressure of all the orifices is less than the "backpressure" of the header pipe, the pressure in your header will be nearly uniform throughout its length. This makes the flow on each orifice nearly equal. Thus big headers and small orifices work better and spray more uniformly.

 

[katmar]

Rather than saying the pressure drop along the sparger must be less than the orifice pressure drop, I would say the pressure drop along the sparger must be much less than the orifice pressure drop. This is for the reason given by Duwe6 - you want each orifice to have the same pressure drop if you want uniform distribution.

My Perry says the sparger pressure drop should be less than 10% of the orifice pressure drop to ensure uniformity to within 5%. This sounds about right if the orifice flow rate is roughly proportional to the square root of the pressure drop.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[ione]

akshey,

Think of a header with multiple branched lines departing from it. If you want to have an even flow distribution, that is if you want your entering flow is equally partialized amongst the take offs, you have to ensure the pressure drop in your header is by far lower than those that characterize each branched line. Now you should see where I want to go. The sparger is in the same condition as that of the header above described (you only have orifices instead of branched lines).