Gas-Liquid transport in ducts

[EngBrandao]

Hi,

A two-phase fluid flowing in a pipe (6 in) which the proportions are:

W gas: 1467 kg/h ρ gas = 6,5 kg/m³ Q gas = 225,7 m³/h
W liq: 22969 kg/h ρ liq = 943 kg/m³ Q liq = 24,4 m³/h

W total: 24436 kg/h Q total: 250,05 m³/h

What is the velocity of the liquid in this tube 6 in. sch 40 (DI = 0.1541 m)?

Thank you.

 

[RaRo]

Fictitious velocity in gaseous phase: 3.36m/s
Fictitious velocity in liquid phase: 0.36m/s

Supposing a homogenous mixture without any interaction, the velocity in your pipe would be 3.73m/s

But this inquiry should not get any reply. With the data given, the answer will always be V=Q/(PI()/4*DI^2) in any homogenous unity system

 

[EngBrandao]

So

The velocity of the fluid in the pipe would be:

Q = V.A

v = (250.05 / 3600) / (pi * 0.1541 ² / 4)

Liquid velocity in the pipe: 3,724 m/s the same Velocity of the gas as was used the total flow and not only the flow of liquid?

Thank you.

 

[LittleInch]

The question cannot be answered as the issue is that the gas will exxpand and reduce in density as it flows along this 62 line of unknown length. As it does so it gradually takes up more and more of the space in the pipe and increases in velocity. The liquid takes up less and less of the fraction of the space and essentially blown along by the gas increase in velocity.

Therefore unless the proerties relate to the specific location where you want ot know the liquid velocity (why ??) you need a proper analysis program to work it out.

The density and volumetric flow of the gas look like thay are at standard conditions (i.e. 1 bara, 15 Deg C). Without konwing the pressure at the point of interest you can't begine to estimate the velocity as you don't know if the pipe is 90%, 50% or 10% full of liquid.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Tauwen]

There are too many "unknowns" to give a good answer. The fluid is some kind of homogeneous mist or the liquid is in bigger droplets? How turbulent is the flow? Is it a straight pipe line? Is there any liquid segregation? Ect...

Maybe if you share more data or the reason why do you need the liquid velocity we could point you toward a method or guidelines for an estimation.