Figure 4 Coke catcher device
Figure 5 Vortex stabiliser at base of the secondary cyclone
Figure 3 N ew regenerator cyclone con iguration
jeopardised downstream operations in the fractionator, resulting in plugging, blockages, and extensive manual cleaning efforts to rectify the situation. To address the coke plugging issue and safeguard the dipleg entrances, proprietary Shell technology was intro- duced in the secondary cyclones. The upgrade involved two main components: a coke catcher and a vortex sta- biliser. The coke catcher is shown in Figure 4 . Installed at the entrance to the dipleg, it acts as a sieve, trapping larger coke particles that could cause dipleg stalling. The trapped particles are gradually eroded during normal operation, and the device can be manually cleaned through an external access hatch if required.
The vortex stabiliser is seen in Figure 5 . Situated at the base of the cyclone, it features an assembly supporting a vertical component that anchors the vortex to the base of the cyclone. In turn, the axial yaw is reduced, and erosion of the refractory lining is prevented. Furthermore, the vortex stabiliser reduces dipleg gas up-flow and eliminates dipleg stalling. The implemented upgrades yielded significant benefits to the unit’s operation. The introduction of the coke catcher and vortex stabiliser successfully reduced catalyst losses and eliminated the problem of dipleg stalling in the sec- ondary cyclones. Over the course of 12 years and multiple thermal cycles, there were no recurring episodes of coke plugging at the dipleg entrances.
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Revamps 2023
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