Spent & Regen CAT Standpipes
Benefits of Regenerator TRU-SCAN® and Stationary Monitoring
- Characterize catalyst flow
- Study the effects of stripping steam and supplemental aeration
that might influence the catalyst flow regime
- Scan results can justify outage for maintenance repairs
- Provides operational data needed to make changes to the re-circulation
rate
For the sloped section of a standpipe, because of gravity, gas bubbles
tend to move along the top while the catalyst particles move along the
bottom wall. It is important to properly operate the steam injection nozzles
(number and location) to avoid de-fluidization or stratified flow. A TRU-SCAN®
is performed using a vertical slant scan for a sloped pipe that can be
applied to characterize the catalyst flow in the spent or regenerated
catalyst standpipes. The slant scans are frequently used to study the
effects of stripping steam, supplemental aeration and other factors that
might influence the flow regimes of the catalyst in sloped pipes.
TRU-SCAN® stationary monitoring is used to perform a slugging study,
which is designed to observe and record density fluctuations over time
as the catalyst circulates. Bubbles can form for as long as two minutes,
restricting catalyst flow. Scan results can often justify a short outage
to correct any problems associated with the standpipe. Customers can also
make changes to the re-circulation rate to determine the affect of the
fluidized flow density profile in the standpipes.
A TRU-SCAN® along the length of a standpipe may also reveal a blockage.
Two scans of one standpipe showed an area of very high density with a
quick change to a very low density just below. It was apparently a blockage
with catalyst building up above the blockage, but cascading past on one
side creating a vapor pocket underneath. At shutdown, a piece of refractory
was found lodged in the standpipe.
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