calculating force due to choked flow on Flare

[Bp20]

Hi every one I have a question.
Is it possible to calculate the load due to chocked flow on flare header according to below formula
F=2rA V^2


r=Density
A=Area
V=Velocity

 

[hydtools]

I would think you have to use force and momentum change calculation. Like nozzle force calculation.

Ted

 

[DSB123]

What is chocked flow? Do you mean choked flow?

 

[Bp20]

yes Choked flow
sorry for misspelling.

 

[davefitz]

The problem was solved for the reaction at safety valve exhuast pipes, see B31.1 or otehr codes regardign releif valve exhaust piping . Safety valves flow is almost always choked flow( inlet pressure > 2*exhaust pressure), original tech paper that the code calcs is based on the Bechtel/Liao paper of 1971.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[LittleInch]

It's possible to calculate most things but what load are you talking about?

Axial load?
load on the connecting flange?
load on an elbow?
Load on the flare nozzle?


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

 

[Bp20]

thanks for responding
I mean Momentum loads because of high velocity in flare line.

 

[LittleInch]

So momemtum on an elbow?

Flare lines are normally pretty thin and don't like high velocities, certainly not sonic.

You're going to need to provide a lot more details of you want any good help here.

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

 

[bitakhp]

Exactly momentum on the elbows.
But if the velocity is so high ?
Thank you so much

 

[davefitz]

Refer to :" Analysis of Power Plant Safety and Relief Valve Vent Stacks" by G.S. Liao, Bechtel Power Corp., Transactions of the ASME, november 1974

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[bitakhp]

Thank you so much