Q&A

(2016) Question 35: What are possible causes do you see of high product nitrogen in a naphtha hydrotreater processing coker naphtha? Please include monitoring, identification, and troubleshooting techniques, inside and outside battery limit considerations, and mitigation options.

Daily monitoring of feed nitrogen and distillation, via the Sim Dist (simulated distillation) method, will allow the refiner to adjust reactor temperature or control the final boiling point to meet the desired product nitrogen.

(2016) Question 36: Which refinery water sources do you accept for hydrotreater water wash (e.g., stripped fractionator overhead water, stripper sour water, etc.)? What are typical water quality guidelines?

Water wash systems must be designed well, with good water contact and draining, or the wash can create significant corrosion concerns, potentially resulting in process safety incidents. MPC experienced this first-hand with an intermittent wash system on an NHT unit.

(2016) Question 38: What do you see for the future of ebullated bed technology considering changes in crude quality and availability?

With the worldwide requirement for higher conversion of residue into lighter, more valuable transportation fuels such as diesel remaining firmly in place, we very much see ebullated-bed (EB) residue hydrocracking building on its current trend as a bottom-of-the-barrel upgrading technology of choice going forward. Investment in this commercially proven, well-established technology is a way to increase complexity and ensure long-term survival in an increasingly volatile marketplace.

(2016) Question 39: Please summarize the current status of slurry hydrocracking technology commercialization.

Slurry hydrocracking technology has been commercialized in China (VCC) and Italy (EST) in the past two to three years. Both facilities have demonstrated expected performance, including conversion and selectivity. The reliability of slurry hydrocracking is still an open question as these units have only been in operation for a short time. Additional VCC commercial units are scheduled for startup in the next 12 months.

(2016) Question 40: As it relates to overall catalyst cycle life management, please address the following issues: What are typical cascading practices for catalyst reuse after regeneration and eventual disposal that you employ? What quality control, catalyst properties and performance specifications, and/or warranties do you have in place for regenerated catalysts? What are some of the key decision criteria you use in determining whether to send a catalyst for metals reclamation, r

First, a response to the question: What are typical cascading practices that you employ for catalyst reuse after regeneration and eventual disposal? As the leading catalyst regenerator, Eurecat sees NiMo and CoMo hydrotreated catalysts (regenerated and regenerated plus rejuvenation) in ULSD, jet, kerosene, naphtha, and gas oil hydrotreating units.

(2016) Question 41: What are the considerations you use for extending hydrogen plant catalyst life cycles (i.e., lower production rates, furnace tube failure, etc.)?

There are many parameters affecting the hydrogen plant catalyst life cycles, such as lower production rates, furnace tube failure, unplanned plant shutdowns, larger catalyst volumes, elevated energy consumption, and finite ZnO/S (zinc oxide/sulfur) capacity. Lower Production Rates will obviously result in longer catalyst lifetime due to a lower gas velocity over the catalyst.

(2015) Question 29: What are the likely causes for temperature excursion events in a hydrogen plant?

Hydrogen plant temperature excursions are possible in several of the catalyst vessels and are usually observed in association with the water/gas shift reaction. During normal operation, the high, medium, and low temperature shift reactors display an exothermic reaction.

(2015) Question 30: What factors influence your decision to conduct air versus inert reactor entry for catalyst changeout? For, what methods do you use to avoid stress corrosion cracking?

For us to enter a reactor that is under an inert atmosphere, the conditions need to warrant it, such as when there are large amounts of pyrophoric material still present, when a specific job is required, an old catalyst needs to be vacuumed out for sampling purposes, or if there is filtration material on top that requires removal in order to allow the catalyst below to dump freely.

(2015) Question 31: What are your current safe practices for sour water monitoring? What are your preferred analytical methods/sampling frequency used to measure NH3/NH4HS (ammonia/ammonium bisulfide)?

The primary concern with sour water sampling is exposing operators to H2S and ammonia, which will evolve off the liquid as it is collected into the sample bottle. Typically, most of our plants would take an approach of ensuring that the operator pulling the sample was in supplied air.

(2015) Question 32: What is your suggested minimum temperature required to achieve adequate metals removal in the demetalization (demet) catalyst to protect primary treating catalyst in FCC and hydrocracker pretreaters?

The suggested minimum reactor temperature required for adequate metals removal is going to be metals specific. For silicon, the temperature is definitely greater than 570°F; and for nickel and vanadium, we suggest greater than 600°F. Now higher reactor temperatures may be required for adequate removal, depending on the space velocity through the metal-strapping catalyst and whether or not there may be a tolerance issue with the primary treating catalyst.

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