Bakeout Cures Excessive Pressure Swings

This past weekend I performed a bake-out on a five tower RTO. For the past few months, this unit had been operating as a four tower due to excessive pressure swings, from 15" WC to over 31" WC. These pressure swings forced the plant to shut down multiple sources, adversely affecting their production. The swings also played havoc with the 140,000 CFM draft fan, placing an inordinate amount of stress on the main draft fan, as it tried to maintain a consistent inlet static pressure. The result was excessive and rapid speed fluctuations. The resulting stresses fractured the 6 foot diameter wheel in multiple places.

After the bake-out, the RTO began operating as a normal five tower. The pressure swings were gone, replaced with a consistent inlet static pressure. The unit now operates with a modest differential pressure drop (between 9 and 10" WC).

The picture is a time-lapsed shot that was taken during the bake-out. The orange streaks are embers, and the temperature inside that vessel was around 850F at the time the photo was taken.  This is looking through an access hatch, in the outlet manifold, at the plenum region of tower 4. The outlet valve is open and the embers are being pulled free from the ceramic media, and are heading toward an exhaust fan that will shoot them out of a stack.