Inlet nozzle: Tangencial x Radial

[User2000]

Some suppliers recommend a tangential nozzle inlet to help the separation. Other supplier says it makes difficult do predict the vertical gas flow patter and recommends a radial inlet.
Some petrochemicals companies recommend to use tangential flow when there is deep vacuum. In this case the velocities are high and the density of gas is very low. So the drag resulted by the disturbed flow is not a big problem because gas density makes the drag weak, although it has a high velocity. I am not sure because the drag depends on Velocity^2 and Density^1. So velocity seems to be more important. These companies recommend also a higher height between the inlet and nozzle gas outlet when using tangential inlet.

Does somebody hear anything about? I do not have any number to compare both inlets. Does anybody has more information?

Thanks

Faleiros

 

[StoneCold]

Faleiros
Tangential nozzle on what? And what application would help us out a lot.

StoneCold

 

[User2000]

StoneCold

Sorry. Let me explain in details.
In a vertical liquid-gas separators there are some possible arrangements:
a) Radial inlet. It's the classical vertical separator where the inlet is placed at perpendicular position related to the drum.
b) Tangenial inlet. It is a variant where the inlet is placed at the border of the drum.
c) Internal devices inlets. There are several variants where same impingent plates and similar devices are placed to help the separation.

My application has small gas/liquid mass ratio, but is under deep vacuum so the gas/liquid volume ratio is very high.

Faleiros

 

[25362]

Faleiros, kindly answer StoneCold's query.

As an aside, if there is a tendency to foaming, any mechanical device that provides more liquid surface, as for example, horizontal separators, are recommended, since it has been proven that the rate of foam dissipation is roughly proportional to the liquid surface area.

I've also seen steam coils been used to break foams by direct contact.

 

[Montemayor]

Faleiros:

If you are going to contemplate using a tangential entry nozzle into a vertical separator, I hope you have sufficient information to size and locate it. I know of no one who has had the mathematical genius to credibly model the effect of inlet mixed phase velocity (& what kind of mixed phase?), diameter, vapor space height, disengagement requirements, etc., etc. I don't expect to find it or hear of it in my lifetime. There are two many variables, in my opinion, and too much empirical dependence to come up with a credible theoretical model.

I've done it both ways, and never saw the difference in separation efficiency. But, in all fairness, I never took the inlet velocity into consideration and was able to measure the results (in particles or particle size, out the exit). As a result, I simple placed all inlets on the vertical vessel's centerline and let it go at that. I have always increased the nozzle size at least one or two sizes in order to reduce the entrance velocity into the vessel. I've done this because it follows the logic of the type of gravitational (stoke's law) separation that I'm applying in these type of vessels (Brown-Souders relationship). And it has worked to this day.