Steam Flow in pipes
Steam Flow in pipes
(OP)
Hi there,
Steam is flowing through a pipe DN 100 from 5 barg and released it through the atmosphere.
I'm thinking of how can I calculate the steam flow or velocity in the pipes.
I've been looking through the internet and found two different formulas and I believe these implies to incompressible flow only:
dp = 0.6753*10^6*q^2*L*(1 + 91.4/D) / ρ*D^5
dp = (8*f*D*ρ*L*Q^2)/(pi^2*D^5}---> Darcy–Weisbach equation
Can anyone explain what is the difference between the two and how do I fit it to apply on steam applications?
Steam is flowing through a pipe DN 100 from 5 barg and released it through the atmosphere.
I'm thinking of how can I calculate the steam flow or velocity in the pipes.
I've been looking through the internet and found two different formulas and I believe these implies to incompressible flow only:
dp = 0.6753*10^6*q^2*L*(1 + 91.4/D) / ρ*D^5
dp = (8*f*D*ρ*L*Q^2)/(pi^2*D^5}---> Darcy–Weisbach equation
Can anyone explain what is the difference between the two and how do I fit it to apply on steam applications?





RE: Steam Flow in pipes
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Steam Flow in pipes
Amen, Latexman, Amen......
I am on my third copy...... worn out the first two....
MJCronin
Sr. Process Engineer
RE: Steam Flow in pipes
MJCronin
Sr. Process Engineer
RE: Steam Flow in pipes
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Steam Flow in pipes
I agree with the advice to purchase the Crane manual. It is a very useful document. For calculating steam flows in most plant situations where the velocities will be in the 50-100 ft/s range you can safely use the isothermal compressible flow equations from Crane. However, in your situation where you are venting to atmosphere you could have much higher velocities and you should check for the possibility of sonic (choked) flow.
Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Steam Flow in pipes
I definitely need to have the technical manual looking at the reponse here.
RE: Steam Flow in pipes
For the former case then the Fanno flow equations would be used to compute the flow that is choked by pipe friction, and in the latter case the ANSI equations for flow through a choked valve would be used. It would yet be necessary to confirm the valve back pressure was less than 3 bar a to confirm the valve was yet choked, so the normal pipe pressure drop equations would be needed to confirm the value of the valve backpressure. Basically the procedure would be to assume a flow, then calculate backwards from the pipe exhaust ( at ambient P ) what the valve back pressure would be. The confirm the flow rate through the valve. Through progressive iterations a solution is found.
"Nobody expects the Spanish Inquisition!"