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(2017) Question 31: What are the potential impacts to hydrocracking units [i.e., deactivation rate, HPNA (heavy polynuclear aromatics) formation, etc.] as heavy coker gasoil (HCGO) rate/endpoint are increased?

Processing heavier and cracked feedstocks poses many challenges to the hydrocracking unit. Thermally-cracked feedstock such as HCGO, apart from being unsaturated, has relatively lower API, higher sulfur, and nitrogen content, higher proportion of C7 insoluble, and Conradson carbon residue (CCR). An increase in the HCGO distillation endpoint results in a significant increase in the proportion of polynuclear aromatics (PNA) and asphaltenes, both of which are coke precursors, which results in an exponential increase in catalyst deactivation rates. 
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(2019) Question 41: How reliable are main air blower check valves?  What are some improved designs or some things to avoid?  Are there any alternatives?  If multiple branches, is there one check valve in the main branch or one check valve per branch, where is it located?  What is your maintenance or inspection best practices?

How reliable are main air blower check valves?  What are some improved designs or some things to avoid?  Are there any alternatives?  If multiple branches, is there one check valve in the main branch or one check valve per branch, where is it located?  What is your maintenance or inspection best practices?
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(2019) Question 49: What are your reliable methods to monitor expansion joint temperature?  Are some joints more critical than others?  What temperature range is acceptable?  How do you increase or decrease temperatures if they are out of the desired range?

What are your reliable methods to monitor expansion joint temperature?  Are some joints more critical than others?  What temperature range is acceptable?  How do you increase or decrease temperatures if they are out of the desired range?
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(2019) Question 53: What are some of your industry practices for upgrading gas plant piping to post weld heat treat to manage carbonate cracking risk?  Please comment on methods such as requirement for new piping, systematic replacement of existing piping, risk-based replacement, or inspection based?

What are some of your industry practices for upgrading gas plant piping to post weld heat treat to manage carbonate cracking risk?  Please comment on methods such as requirement for new piping, systematic replacement of existing piping, risk-based replacement, or inspection based?
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(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.
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(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.
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