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14 June 2012

The use of acoustic inversion to estimate the bubble size distribution in pipelines

Science Daily -

The ability to measure gas bubbles in pipelines is vital to the manufacturing, power and petrochemical industries.

In the case of harvesting petrochemicals from the seabed, warning of bubbles present in the crude that is being harvested is crucial because otherwise when these bubbles are brought up from the seabed (where pressure is very high) to the surface where the rig is, the reduction in pressure causes these bubbles to expand and causes 'blow out'.

A blow out is the sudden release of oil and/or gas from a well and issues with the blow out preventer were key in Deepwater Horizon oil spill (also known as the Macondo blowout) in the Gulf of Mexico in 2010.

Currently, the most popular technique for estimating the gas bubble size distribution (BSD) is to send sound waves through the bubble liquid and compare the measured attenuation of the sound wave (loss in amplitude as it propagates) with that predicted by theory.

The key problem is that the theory assumes that the bubbles exist in an infinite body of liquid. If in fact the bubbles are in a pipe, then the assumptions of the theory do not match the conditions of the experiment.

That could lead to errors in the estimation of the bubble population.ow, a team led by Professor Tim Leighton from the Institute of Sound and Vibration Research at the University of Southampton, has devised a new method, which takes into account that bubbles exist in a pipe.

Professor Leighton and his team (Post-doctoral research fellows Kyungmin Baik and Jian Jiang) were commissioned to undertake the work as part of an ongoing programme to devise ways of more accurately estimating the BSD for the mercury-filled steel pipelines of the target test facility (TTF) of the $1.4 billion Spallation Source (SNS) at Oak Ridge National Laboratory, Tennessee, USA one of the most powerful pulsed neutron sources in the world.

Full story...

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