Q&A

(2014) Question 40: What are your best practices when crimping pigtails on a hydrogen plant? Are there any metallurgical limitations?

Most owners take the unit down and pinch off the top and the bottom pigtail with a double crimping device and physically separate the pigtail from the cat tube. Itis recommended that the cat tube also be removed. This prevents a damaged or unused tube from distorting and affecting adjacent tubes or perhaps even falling in the firebox causing other damage.

(2014) Question 41: Can you comment on the use of liquid and/or vaporized naphtha as feed and/or fuel to a hydrogen generation unit?

Johnson Matthey has vast experience in direct reforming of naphtha feedstocks in SMR’s for hydrogen production. The naphtha needs to be vaporized to be processed in the SMR based hydrogen plant. It takes less heat load to reform a mole of naphtha as compared to natural gas, but more COx will be produced, and the carbon formation potential is higher in naphtha which can have an average carbon content of C6 and a tail to C20.

(2014) Question 42: What design modifications, such as pre-reforming and ATR (Autothermal Reforming), do you consider for greater feedstock flexibility, higher efficiency and capacity debottlenecking?

One can use thermometry to provide insight on performance and when to optimize. Utilizing a process model to compare actual temperatures vs. estimated slip will give you an idea of adjustments required.

(2014) Question 43: How has the increased processing of synthetic and other opportunity crudes in a refinery impacted the buildup of HPNA's (Heavy Poly Nuclear Aromatics) in the hydrocracker and affected conversion? What are your strategies to address this?

PCA (Poly Cyclic Aromatics) formation is not a function of processing synthetic or opportunity crudes. Some opportunity crudes can be much easier to process by a HCU due to much lighter EPs thus providing extended run lengths. Feed type, quality, severity of the operation, unit configuration and catalyst choice in the HCU are determining factors for PCA formation.

(2014) Question 44: What strategies have you utilized to balance available catalyst life in hydroprocessing units with scheduled turnaround times, and how can this be optimized to increase profitability?

Two scenarios exist when looking to balance hydroprocessing catalyst life with turnaround timing: instances where excess activity is present and instances where there is not enough activity to meet the projected TA schedule.

(2014) Question 45: Has bromide been reported in your hydroprocessing unit feeds or discovered as ammonium bromide in the reactor effluent exchangers? If bromide is present, do you use the same wash water practices for ammonium chloride deposition sufficient to avoid exchanger fouling? What are the possible sources of bromides

Bromine is in group 17 of the periodic table commonly known as Halogens. Halogen means “salt former”. It is this salt forming nature of the halogen group that makes them key in natural compounds. Halogen anions of Fluoride, Chloride, Bromide, and Iodide are present in living organisms. Further Bromide is present in all organisms, and organobromine is the most common organohalide.

(2014) Question 46: Silicon uptake on hydrotreating catalysts is an increasing problem. (1) What operating conditions favor maximum silicon pickup by the catalyst? (2) Are there differences between silicon from coker antifoamsand other sources? (3) Does the presence of other contaminants such as nickel and vanadium affect the silicon pick-up by the catalyst? (4) What best practices are you using to monitoring silicon pick-up by the catalyst?

Silicon in feed streams to Hydroprocessing units can pose a threat to catalyst performance and must be properly managed. Silicon acts as a poison to the catalyst by depositing on the surface of catalyst particles blocking active sites and reducing critical HDS and HDN activity. Silicon can be found in a wide range of feed streams and is a concern for all hydrotreaters processing naphtha, distillates, and vacuum gas oils.

(2014) Question 47: How will an abundance of low-cost hydrogen impact growth/expansion plans for your refineries?

Low-cost hydrogen shifts the focus of the hydrogen addition processes (hydrotreating and Hydrocracking) from hydrogen efficiency to maximum uptake and volume expansion. Once hydrogen becomes cheaper than the crude-based materials being processed any additional hydrogen uptake makes money.

(2014) Question 48: Can DAO (Deasphalted Oil) be processed in a full conversion hydrocracker and if so what concerns would need to be considered?

Typical DAO stream composition metals (5 -100 wppm), Conradson Carbon (2 – 10 %wt), Asphaltenes (heptane insoluble of 500 -1000 wppm or more) and distillation endpoint (1300-1500 F or more) are detrimental to achieving economic catalyst life and conversion at hydrocrackers.

(2014) Question 49: What experience have you had in identifying the incompatibility of feeds to a Hydroprocessing Unit? Can these feeds create pressure drop issues? What kind of feeds/compounds are typically incompatible? What test(s) do you suggest? Are there any solutions such as catalyst loading modifications to eliminate typical issues?

Feed stock incompatibility has typically been observed in VGO hydroprocessing and is related to the precipitation of asphaltenes.

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