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Tower Scan

Maldistribution Suspected in a Packed Bed

Refinery under the lightsMaldistribution was suspected in a packed bed of a Main Fractionator, on a major European FCC unit. A TRU-SCAN®/Tru-Grid™ Scan was used to investigate the transfer/parting box arrangement immediately above the bed. In addition, a TRACERCO Diagnostics™ Tomography scan was performed towards the top of the bed to supplement the traditional tower scan, in an attempt to locate any areas of maldistribution within the bed. The results of the tower scans carried out are below - click on the image below for a larger view (the transfer and parting box sections extending down to the top part of the bed). These showed an increased liquid level on the East side of the transfer box, with the density in the East side of the bed around 10% higher than on the West side.

Maldistribution in a packed bed

A full TRACERCO Diagnostics™ Tomography scan was undertaken on the bed around the top elevation. This involved 18 source locations around the tower and detectors at 10 positions for each source location. By knowing the source and detector separation at each point of measurement a density can be calculated at each intercept position by the use of simultaneous equations.


The above is a 3D representation of one set of scans that were performed - click on the image for a larger view.

The results correlated with the findings of conventional TRU-SCAN®/Tru-Grid™ Scan, in that a region of lower density was detected on the West side of the bed whilst there was a region of higher density on the East side.

The above work, part of an on-going development programme with some key customers, will give our clients much greater detail regarding overall bed densities and will be offered alongside the TRACERCO Diagnostics™ Distribution study to provide a comprehensive survey of bed performance.

If you would like to discuss any aspect of its use or become involved in its further development and refinement then please contact us.

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