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Clear/transparent pipe section

Clear/transparent pipe section

Clear/transparent pipe section

Hello all,

In our pilot plant, we have a high pressure (up to 150 bar and approx 50 deg C) quarter inch pipeline accommodating two-phase flow of gas bubbles in a flowing liquid. For a variety of reasons, it is difficult to predict the bubble dynamics and even the solubility of the gas in the liquid.

Devices exist to give online bubble measurements but for our high pressure case would prove very costly.

One idea is to install a small section of transparent pipework in the line which would give us an excellent idea of the homogeneity/mixing within the flow.

Does anybody have recommendations relating to this?

Many thanks,
Stephen O'Brien

RE: Clear/transparent pipe section


This sort of thing will do your P/T if the geometry of the viewing chamber isn't critical to understanding what's going on in there.

If the geometry matters, you might be able to find one of the sight glass manufacturers (Klinger, Jerguson, Penberthy, Jacoby Tarbox etc.) who will build you an armoured sight glass with a very thick piece of quartz or glass tube inside a secondary containment consisting of a more standard sight glass, but this would be custom- and your ability to truly see what's going on in there will be impaired as this glass tube will NOT be optical quality.  

Another option would be a thinner tube inside a sight glass padded with nitrogen etc. to control the differential pressure across the inner glass tube.  More complex, but possibly more likely to give acceptable viewing.

RE: Clear/transparent pipe section

You could also look at using a small bulls-eye level gauge but I don't know if they make them small enough - you could install it in a tee and observe the bubbles through the glass - alternately, buy a level gauge and flow straight through it.

RE: Clear/transparent pipe section

For this type of application, I've often used a Jerguson, Penberthy, or Jacoby Tarbox visual level gauges rated for 200 bar and over.  For pilot plant work, a 1" size on these gauges is more than adequate, and they are often available off-the-shelf.

There are two types of level guages: the reflex type and the transparent type.  Use the latter and you will find that you can see all that is flowing through the system.

The only handicap with these gauges is that they are HEAVY and need to be well supported and restrained.


RE: Clear/transparent pipe section

Or you could take a look at the Cidra Sonartrak GVF device.
This is a clamp on sonar (not ultrasonic) device.
This is downhole stuff so the technology is there but maybe not in the size you need. 2" seems to be the smallest pipe doiameter they handle. But I suspect we can consider much of this well drilling logging technology much as Formula 1 is to the family car, a test bed for new technologies.

But I think this bottles out at 20%GFV.
If you are dealing with CO2 in coffee extract then 50% is a more reasonable target.
The only other technology I can think of is the Emerson 7845/35 EGA (Entrained Gas Amplifier) density meter. This will measure density to 0.5% from 0-100% GVF. The smallest they've done is a 1/2" (not currently in production but they have drawings and if there is a market.....). Not sure what pressure this would handle though.

How uniform or homogeneous your two phase flow is will govern how stable the measurement is would be my suggestion.
I don't know exactly what you need, but this would give some helpful data.

Given the gas volume fraction and the density of the liquid phase, you ought to be able to deduce the amount of gas that is flowing as bubbles and the amount that is dissolved.




RE: Clear/transparent pipe section

Many thanks all!

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