Q&A

(2018) Question 11: What constitutes adequate quench reserve when you process cracked feedstocks in hydrotreating units? In hydrocracking units? What if a mixture of both gas and liquid quench is used?

Maintaining control means that the dog walker – needs to be able to hang on to the dog – even if it starts to walk or run away. This takes adequate reserve strength - and an early detection and response when the dog just begins to become distracted or when we begin to feel the pull on the leash.

(2018) Question 12: Discuss impacts of hydrotreating operations required to meet Tier III regulations. Highlight the benefits and concerns of pretreat versus post treat operations including; impacts on cycle length, FCC yields, octane from post treating options, and gasoline blending.

Regulatory specifications for the gasoline and diesel pool, which are constantly evolving, have been in the forefront of refiners’ challenges in the last 15 plus years. In particular, the gasoline sulfur regulations have been a main driver for the remodeling of many refineries’ configurations.

(2018) Question 13: What factors do you consider when co-processing jet fuel in a distillate hydrotreater versus processing the jet separately (including feedstock and unit consideration)?

There are several considerations when deciding if jet fuel and diesel should be co-processed or hydrotreated separately. The most important consideration is if the jet fuel will be blended into the diesel product or if separate products are desired. The decision may depend on if you are looking at constructing new facilities or making the best use of existing equipment.

(2018) Question 14: In your experience, what operational factors contribute most to utility costs in hydrotreating units?

The biggest contributor to utility cost per barrel in a hydrotreater is probably the unit operating pressure. Higher pressure units require more energy to pump up the charge, hydrogen, amine and wash water.

(2018) Question 15: As hydrotreating catalyst development continues with the emphasis on activity and saturation, how has this changed optimization strategies for the entire hydrocracker?

Advances in hydrotreating catalyst technology continue to produce steadily increasing performance for hydrocracking pretreat service. These improvements result in increased HDN and aromatics saturation performance which are key to optimizing overall hydrocracker performance.

(2018) Question 16: How are you performing in-situ sulfiding for hydroprocessing catalysts protecting your waste water units from water soluble organic chemicals and their fuel gas system from non-decomposed mercaptans?

The exact temperature needed to achieve complete decomposition is dependent on the pressure, the catalyst type, and the space velocity in the reactor.

(2018) Question 17: Where do your route your disulfide oil from caustic treatment? If disulfide oil, that may contain caustic or other contaminants, is routed to a hydrotreater, what are preferred methods for treating it to avoid fouling exchangers, furnaces and catalyst?

Disulfide oil is gravity settled out of the regenerated caustic in a settler vessel. A slip stream of cold Naphtha or #1 fuel oil is injected and used to help provide a larger volume of hydrocarbon to dissolve the disulfides and aid in separation (Sponge Oil).

(2018) Question 18: Vacuum Gas Oil (VGO) Hydrotreaters are being pushed to process heavier feeds while maximizing Fluidized Catalytic Cracking Unit (FCCU) performance while meeting Tier III gasoline specifications. How are you balancing increased severity and cycle length? What considerations do you give to feed quality and upstream unit operations?

The FCC unit has long been the workhorse in the refinery to achieve relatively low-cost conversion of heavy crude components (VGO, HCGO and some atmospheric residue) into gasoline, butenes for high-octane alkylate production, propylene and LCO diesel blend components.

(2018) Question 19: What considerations do you use for designing a hydrocracking reactor? What criteria do you use to determine number of beds, diameter, and beds’ lengths?

Hydrocracking reactor design is a proprietary technology with each licensor having their own specific design practice based on operating experience, catalyst technology, and engineering expertise. It is not the purpose of this forum to reveal proprietary technology, but to improve refiners’ operations through shared experience.

(2018) Question 20: What considerations do you give to co-processing or block mode operations with renewables in an existing hydroprocessing unit?

In all scenarios, a refiner must consider their RFS obligations, potential biodiesel tax incentives, biodiesel merchant market, refiner’s existing hydrotreating units’ utilization rates, capabilities, and designs, renewable feedstock types, availability, price, and pre-treatment requirements, and product specifications and storage constraints.

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