Ultrasoic flow meters

[joisy]

Dear All,

can you please give some feedback on what you think of the usage of ultrasonic flowmeters and their accuracy. We gonna install some on the pipeline between offshore platform and onshore terminal.

thanks

 

[glennpan]

Joisy,

What do you have going through the pipeline? There are two types of Ultrasonic flow meters, Doppler and Transit time.

Doppler is the older technology of the two and works very well on dirty liquids, and liquids with solids. With this type of meter, an Ultrasonic pulse is projected into the pipe at a 90° angle and reflects off of air bubbles or particulates. A frequency shift occurs that is linear to the flow rate that provides the measurement. Accuracies are generally in the 2% range.

Transit time has two transducers and receivers that send a pulse both upstream and downstream, and since the pulse will move slower against the flow, the time difference between upstream and downstream pulses are linear to the flow rate. This technology works much better with clean liquids, and is much more accurate than Doppler type meters. Recent advances have allowed Transit time meters to handle up to 20-30% solids. Accuracies can get to 0.5% on cleaner flows.

If you have interest, I can send you information on either of these types of meters.

Glenn

http://www.panner.com

 

[BRT549]

I think the doppler units work pretty well on dirty fluids, but the pipe has to be metallic. They won't work on concrete, plastic, or rubber-lined pipe. If your fluid is clean, I've had good luck injecting air so that the bubbles can reflect the waves.

The sensors have to be 'coupled' to the pipe with goo, like grease or even KY jelly. The sensors can vibrate loose, or the goo can get hot and run out.

In short, they are good flowmeters to slap on to an existing pipe without opening the line up. The ones I've used aren't that accurate or reliable, but I'm probably biased from my experiences with them in the early '90's.

 

[joisy]

This pipeline handles crude oil with about 0.1% of sand, 0.5% of water.

2 glennpan, if not difficult please send it to me at joisy@yandex.ru

thanks to all

 

[nosaMgiarC]

Joisy,

Don't know much about UltSon flow meters so was interested in your post. However I do know a bit about sand. Do you really have 0.1% sand in your oil? This is 1 full barrel of sand per thousand barrels of oil! I'm used to dealing with 20 pounds per thousand barrels as a high value, but you've got closer to 1000 pounds per thousands barrels. If this is correct how do you manage erosion, pipeline pigging and disposal of this quantity of material?

Cheers

Craig

 

[joisy]

yes Craig, wou're right: I 've got the wrong data - sand content as high as 5 pptb. Water is OK