Let’s quickly review some concepts for good caustic scrubbing, caustic strength (not just pH, but also the weight percent sodium hydroxide), contacting of the treat stream with the caustic using pre-mixing or submerged inlets, packing within the scrubber, and caustic circulation to keep the caustic uniform in concentration.

The typical olefin limit in a C5/C6 isomerization unit is 2 to 3%. The olefin content of the feed is constrained by the high heat release that the olefins cause across the reactor. Olefins can polymerize and cause coking on the catalyst in an isomerization unit.

First, there are not a lot of innovative solutions here on this list. For the most part, everyone is doing many of these things already. They are fairly straightforward. First, just maximize the amount of gasoline you are dropping in the distillate.

There are two ways to address the issue: 1) try to increase the coke that you are making and 2) adjust the regenerator. It would be great if you could just adjust how much coke you are making. However, most of the time you are restricted in what you can do with the unit, given your octane targets and the feed flows and qualities are fixed.

The obvious answer to the high-pressure drop would seem to be that you have too many fines on the bags. But realistically, why do you get too many fines? The causes could be that you waited too long to do the reverse jet blowing or, a less common cause, that you are getting hydrocarbon carryover which is causing the fines to clump together on the bags.

HollyFrontier has two CCRs: one at Tulsa that was converted from a semi-regeneration reformer and one at Artesia. We have not done a catalyst change at the Tulsa refinery CCR, but we have done an online catalyst change at Artesia.

Carbon monoxide can form in reformer units as the hydrocarbon reacts with moisture under very low-unit pressure conditions. Typically, semi-regeneration reformer net gas would have nil CO and only a minimal amount in a CCR-type unit. I expect it to probably be on the order of 5 ppm (parts per million), though some units report routine measurements of 10 to 20 ppm CO in their net hydrogen off gas.

If you have a poor octane result, the Best Practice is to blame the lab. Isn’t that what we do? The reality is that there are at least four key components of a sample system that all need some attention: sample conditioning, container contamination, sample degradation between collection and analysis, and the analysis method.

Promoted or multi-metallic reformer catalysts have been a topic of research since at least the early 1970s. They have been tried commercially in various forms over the years, all with the objective of improving yields by suppressing the demetallization reactions.

Assuming the jet fuel is on-spec with regard to other quality parameters, with the exception of perhaps copper strip corrosion and mercaptan sulfur, we have found that instability reaction precursors and catalysts are typically the root causes of JFTOT failures.