Packed Tower Tru-Grid™ Scan
Benefits of a Tru-Grid™ Scan
– On-line hydraulic measurements
– Reveals flooding, damage, liquid maldistribution
– Determine collector tray and distributor liquid levels
– Evaluate operating condition options
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Typically when a bed of packing has fouling there
is a dense area where liquid is held up due to the fouling restriction
causing a density gradient through the bed.
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The complexity of packed towers extends from the simple single bed with
a pipe distributor to a multi-bed tower with complex distributors and
collectors. In any configuration, a Tru-Grid™ Scan reveals the hydraulic
conditions inside a tower as it operates. Levels can be measured on devices
designed to hold liquid and areas of liquid hold-up (possible flooding)
can be detected.
One of the major concerns with packed towers is liquid distribution.
Common causes of liquid maldistribution include: design, manufacturing
or installation defects in distributors or packed beds; damage or plugging;
and process disturbances. The first step to identifying liquid maldistribution
is to perform a Tru-Grid™ Scan to determine the quality of the liquid
distribution through the beds, i.e., liquid channeling down one side.
Scan results from a Tru-Grid™ Scan showing maldistribution as a
problem can provide customers an understanding of the areas of most concern
and allows an opportunity to plan and prepare for the necessary repairs
or modifications needed in advance of a shutdown.
Tracerco’s vast experience has taught us that not all grid scan
results are as they appear. For certain liquid maldistribution detected
on a Tru-Grid™ Scan is a cause for concern. However in some cases
liquid maldistribution patterns, e.g. Annular flow could appear as uniform
distribution from a grid scan. When such a situation is suspected, Tracerco
offers supplemental technologies such as Tru-CAT™ Scans and Tracerco
Diagnostics™ Distribution Studies to further diagnose the problem.
Baseline scans provide a valuable reference that can be used to identify
and monitor patterns in tower performance. Subsequent scans will reveal
areas that are fouled or plugged in the early stages of formation and
may allow operational changes to slow or halt the fouling process, correlations
to be drawn between operating conditions and the rate of fouling or measure
the rate of deterioration caused by the fouling to better prepare for
needed corrective action. In packed towers a baseline scan or a dry scan
can document the scan appearance from the design and layout of the internals
to allow for recognition of more subtle differences in liquid load on
subsequent scans.
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