下游炼化工程

James, walk me through the FCC catalyst loss issue. How bad is it, and what are our options?

Dr. Morrison: The regenerator cyclone system has been showing increasing catalyst losses for the past 4 months. We're now losing 4.5 tons of catalyst per day — the design is 1.5 tons per day. That's three times the normal rate. At $3,000 per ton, that's $13,500 per day in extra catalyst cost. But the real risk isn't the catalyst cost — it's what the lost catalyst is doing downstream.

The lost catalyst fines are being carried into the flue gas system. They're eroding the expander blades — we've measured 0.8 mm of material loss on the first-stage rotor. The expander is a $5 million piece of equipment. If a blade fails, the entire power recovery train goes down — not just the FCC, but the main air blower too. That's a full plant shutdown. And the fines are also plugging the waste heat boiler tubes — we've lost 15% of the steam generation capacity from the FCC flue gas system.

So we're looking at a potential catastrophic failure. Carlos, if we schedule a turnaround now, how long and how much?

To replace the cyclones, the air distributor, and inspect the reactor internals — we need 35 days of shutdown. We have to cool the reactor and regenerator, which alone takes 5 days. The physical work on the cyclones is about 18 days of 24/7 shift work. Then 4 days to reheat and restart. Total cost: $22 million in maintenance, plus about $35 million in lost refining margin during the shutdown — $57 million total.

James, what if we delay and the cyclone fails?

Dr. Morrison: An unplanned failure means 90+ days of downtime — three times the planned outage. And the damage would be far worse. A failed cyclone sends catalyst directly into the flue gas system at full flow — it destroys the expander ($5M), the waste heat boiler ($3M), and the electrostatic precipitator ($2M). That's $10M in equipment damage alone, plus 3 months of zero production from a 60,000 BPD FCC. At $15/bbl margin, that's $270 million in lost profit. My professional recommendation is clear: take the planned 35-day turnaround now, at a cost of $57 million, rather than risk a $280 million catastrophe. This is not a close call.

Tom, your CDU overhead water boot iron levels have been trending up for the past 6 months. You're at 8 ppm iron now — up from under 1 ppm. That's a strong indicator of active corrosion somewhere in the overhead system. The most likely culprit is hydrochloric acid dew point corrosion. When the overhead vapors cool below the water dew point, HCl dissolves in the condensing water and forms a highly corrosive acidic solution. The first place it condenses — typically at the overhead air cooler inlet — gets the worst attack.

I UT-scanned the overhead line this morning. The 90-degree elbow at the air cooler inlet — the one where the thermocouple showed the temperature crossing the dew point — has wall thickness of 5.2 mm. Original was 8.2 mm, Sch 40 carbon steel. That's 36% wall loss in 4 years. Corrosion rate: 0.75 mm/year — the API 571 recommended maximum for carbon steel in this service is 0.25 mm/year. We're running three times the acceptable rate.

The root cause is inadequate neutralization. The neutralizing amine injection rate is too low, and the injection point is too far downstream — the acid has already condensed and attacked the metal before the amine reaches it. We need to: relocate the amine injection point to the overhead vapor line IMMEDIATELY after the column outlet, increase the injection rate to achieve a target pH of 6.0-6.5 in the boot water, and add a filmer — a corrosion inhibitor that forms a protective film on the metal surface. And Javier's elbow — that needs to be replaced at the next opportunity. At 5.2 mm remaining, it has about 2 years of life left at the current corrosion rate, but with the improved chemical treatment, we should extend that significantly.