Exploring Potential Solutions
I had a discussion with Vee Narayan, who was then the field maintenance engineer at the same location. Some ideas came up and we selected one that seemed distinctly attractive. We gathered a team which included riggers and crane-operators to brain-storm this idea. By the end of this session, we had evaluated the risks and found actions to mitigate them. We were satisfied that we had a way to accomplish the job safely.
The main steps were as follows:
- 1. Enlarge the 60" man-way by cutting an opening large enough for the new cyclones to pass through it. Save the cut-out for re-fitting after the last cyclone entry.
- 2. Manually assemble a pulley support on top of the regenerator.
- 3. Place the track crane and the diesel winch, as shown in Figure 30.4.
- 4. Secure a pulley to the neighboring catalyst hopper vessel at suitable height.
- 5. Thread a wire rope and hook system from the diesel winch, through the catalyst-hopper pulley, to reach inside the regenerator via the top pulley and top opening.
- 6. Station the lead rigger and three other riggers, as shown in Figure 30.4.
- 7. With the help of two suitably hung chain-blocks inside the regenerator, transfer a cyclone from its suspension rods to the hook of the diesel winch.
- 8. Lower the released cyclone to man-way level.
- 9. With the help of the track crane hook and a suitably hung chain- block, remove the cyclone out of the regenerator, transfer it from the diesel-winch hook to the crane hook, and lower to ground level.
- 10. Repeat with all ten cyclones.
ll.Install the new cyclones by reversing this process.
Item 1 in this procedure posed a potential problem. The nozzle of the 60" man-way provided structural reinforcement to the shell of the regenerator. By removing the nozzle and flange, we would weaken the shell. This could cause the opening to close slightly in the vertical direction, as a result of the selfweight of the Regenerator. It had the potential to crease the shell at the horizontal diameter of the man-way. There was no guarantee that when we tried to refit the nozzle cut-out made earlier, we would be able to reinsert it, as the hole could now be slightly oval. We could not accept this risk. So we designed a reinforcement girder to strengthen the shell and compensate the temporary loss of the 60" man-way nozzle and flange. This is shown in Figure 30.3. The procedure described above is illustrated in Figure 30.4.