PTQ Q2 2026 Issue

can result in poor regenerator pressure control, causing a reduction in throughput and catalyst circulation rates and resulting in large economic loss. Figure 2 shows an exam- ple of damage to an orifice chamber. Problems created during shutdown Even with reliable operation and monitoring during normal operation, issues can arise during the process of shut- down. By its very nature, the shutdown is complex, with equipment operating in unusual conditions, such as de-in- ventorying, hydrocarbon freeing, and blinding. However, thorough planning of the shutdown and decontamination can help the refinery successfully navigate these unusual conditions. Knowledge from past turnarounds can provide insight into potential pitfalls for the current shutdown. Advance knowledge of issues such as isolation valves that do not hold or drains that are difficult or unsafe to use allows these risks to be addressed before the unit is taken offline. These should be managed by operations, but the process engi - neer can give technical advice, help develop solutions, and document issues and recommendations. Often during unit shutdowns, alternate line-ups can be used to empty vessels and provide adequate heat for decontamination. These abnormal line-ups can introduce foulant and debris into portions of the unit that do not normally experience fouling (see Figure 3 ). Similarly, when inspection results do not reveal what was expected, alter- nate reasons that caused the process issue need to be con - sidered. The goal should be to develop a plan to address the issue, either through a change in operations or a possi- ble scope change, and to outline the next turnaround. All findings and recommended actions should be included in the turnaround report to help the next engineer. These transient operations can also make flow and level man - agement a challenge. These challenges, when not handled correctly, can cause additional damage to vessel internals. Surprise learnings from the past During every shutdown, something unexpected occurs

Debris in dead leg due to blinding locations

Re-deposited debris on absorber packing

Level dropped too quickly causing vacuum, leading to collapsed trays

Figure 3 Issues caused during unit shutdown

during the process inspection, or there are often issues with equipment that were expected but did not occur. If some - thing unexpected is found, it is time to go back through the process data to try and identify when the issue is likely to have started and (hopefully) find the cause. Figure 4 shows an example of fractionator inlet fouling that was found upon inspection and verified by process data. Shutdown/start-up operating procedures With the turnaround planning in place, the next significant effort is preparing for the unit shutdown. Shutdown and start-up are times of increased risk of a process safety event. Well before the start of the turnaround, the shutdown and start-up procedures should be reviewed. Preferably, this should be done as a group review to gain from discussion synergies. Consider evaluating potential hazards if a section of the procedure is skipped or done improperly. Added safe- guards such as a process hazard analysis (PHA) can be

Normalised fractionator inlet dierential pressure

Figure 4 Fractionator inlet fouling

PTQ Q2 2026