forcing gas flow through the branch line

[Dammi77]

Hello , I'm working on a gas plant and there's a place where there's a main gas header and then there's a branch line that takes off from the main header which is the same size as the main header but only 30% flow is required to go through the branch line and 70% through the main header. Would putting an orifice in the main line upstream of the branch can force 30% through branch . Please let me know the engineering behind it and the orifice sizing .

 

[MortenA]

i bet you get lots of replies to this request for "free engineering"

 

[LittleInch]

Well it might, but the engineering is based around the pressure at each end of your main and branch line.

If the end point pressure is the same for both lines and the distances the same then you would have expected the orifice to be on the branch line.

Your question makes no sense without data (size, pressure, flow etc) and drawings / sketches of the system.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

It sounds the request is looking for a quick and simple solution for the operation. If the piping with orifice restriction could be effective in the flow design, there is no need for various instrument control devices.

If the only orifices available, verify how many flow conditions you may excepted in the system, in terms of flow, P&T, etc., and calculate the orifice size as needed for each case. And then, you may use the proper orifice under the specific flow condition as required.

 

[georgeverghese]

You've got to tell us a lot more before we can provide the right solution. At the moment, would suggest you should speak to your lead process engineer to sort this out for you.

 

[LittleInch]

Also putting an orifice plate "upstream" of the branch will simply reduce flow in the main line.

This is where a diagram helps a lot.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MobinNomvar]

Although putting an orifice sounds like the simplest solution, but checking validity of such solution depends on many factors including expected variability of the gas flow, distances between orifices and destination equipment, nature and composition of the gas flow, range of flowrate, to name a few, how accurate this 30/70% control must be, ...

Please share with us what did you come up with.

 

[Iomcube]

If header pressure upstream remains more or less constant orifice will do but if otherwise a self adjusting pressure regulator should be installed