Q&A

(2012) Question 74: We have experienced leak issues around gaskets in cyclical and hot temperature services. What solutions have you developed to eliminate these issues?

At one of our two cokers, we use ring joint flanges from the coker heater outlet to the coke drum inlet and have had no leak issues. At the other coker, we have a short section of piping at the coke drum feed inlet that had raised face (RF) with spiral wound gasket drum (SPWD) that would occasionally leak.

(2012) Question 75: Please describe your best turnaround practice for cleaning and inspecting heat exchanger bundles versus replacement.

KBC is a nonoperating company, so we do not operate any equipment or conduct turnarounds. However, we do know that the bundle must be cleaned for inspection. We are accustomed to seeing hydrolancing or chemical cleaning for less severe services.

(2013) Question 1: What is a typical hydrofluoric (HF) acid inventory (pound of acid per bpdC5+ alkylate), and what steps are refiners considering reducing this volume? What other risk mitigation steps are refiners considering for their HF units?

As you can see on the slide, there is a big variation in the design HF-to-alkylate ratios. The order of older units, as denoted by old Heritage-Phillips and old Heritage-UOP types, has fairly high ratios. The more modern ones were designed with lower ratios.

(2013) Question 2: Have seal-less pumps (magnetic drive or canned pumps) been used successfully in HF and sulfuric acid alkylation units? What services are considered for this equipment?

Yes, sealless pumps have been successfully used in both HF and sulfuric alkylation processes, typically in the acid rerun system for the HF process and fresh acid service for the sulfuric process. However, the API-610 sealed pump is, by far, the most commonly used pump based on the fact that API 610 pumps are familiar within the refinery for the Maintenance and Projects groups and also because of their robust design and relatively low initial cost.

(2013) Question 3: What drives the decision to load presulfided, presulfurized, or oxidized catalyst in naphtha hydrotreaters? What are the different safety considerations for each case?

I would like to begin my responses by grounding us in some definitions. Pre-sulfided catalyst is the catalyst that is delivered with an active metal sulfide site. Pre-sulfurized catalyst is catalyst in the oxide form but which then has added to it an organic sulfur compound. The metal sulfide sites are then formed in-situ during the startup process. Finally, sulfiding is the process of injecting a sulfur compound into the reactor for in-situ sulfiding after the catalyst is loaded.

(2013) Question 4: Is there any experience producing on-specification jet fuel without any sulfur/mercaptan treating, including any form of caustic, from feedstocks produced from ‘tight’ formations? What other jet specifications are adversely impacted by the changed feedstock?

The main idea here is that there is no real change to the way you make jet fuel based on tight oil. There may be slight changes to the freeze point due to the paraffinicity of the tight oil, but that is actually just dependent on the tight oil itself. If that is the case, really all that is required is a cutpoint adjustment in the crude unit to get on-spec on the freeze.

(2012) Question 5: Reforming of feedstocks from ‘tight oil’ crudes offers unique challenges such as low naphthene and aromatic (N+A) content, lighter feed, and differences in coke yield.What are refiners doing to address these challenges and generate opportunities for these new crudes?

From a project standpoint, there have been inquiries related to tight oil and proposals generated, but not a significant number of actual projects realized for revamping units. It appears that most refiners are able to accommodate the tight oil in their existing units. Some of this accommodation has to do with the naphtha area capacity issues in the U.S. of which I am sure everyone is aware.

(2013) Question 6: Has isomerization become more important as feedstocks have become more paraffinic with the increased processing of ‘tight oil’ feedstocks? Do ‘tight oil’ feedstocks contain more benzene?

For this question, I looked in our assay database at the light straight-runs since we spoke a little about isomerization then. Really, if you think about benchmark crudes like WTI (West Texas Intermediate) and WTS (West Texas Sour), and if you consider Bakken and some of the Eagle Ford crudes as tight oil crudes, then the only one that really pops out as being meaningfully different is the Eagle Ford Light or the Eagle Ford condensate that some people are running.

(2013) Question 7: Given challenges in gasoline Reid vapor pressure (RVP), benzene, low-carbon fuels, and other requirements, are refiners considering expansion or other changes to make more alkylate? Has increased catalytic polymerization become a consideration?

UOP has not observed a big uptake in project activity related to this issue. However, we have observed more interest in revamping existing alkylation units rather than new projects.

(2013) Question 8: What is the industry experience with de-isobutanizer (DIB) feed pre-heatexchanger or reboiler fouling? What are the typical causes of the fouling? How do you mitigate this problem? Comment on both HF and sulfuric technologies.

I am going to talk about HF alkylation units only. The feed pre-heaters for the isostripper or main fractionator have experienced corrosion and fouling. There are several possible causes. One is getting the metallurgy, which is typically carbon steel, too hot. If you go over 160°F in the presence of HF, it gets very corrosive; so, you can lose metal that way.

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