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(2016) Question 69: Our FCC unit is limited by coke burn and high regenerator temperatures. What catalyst and operational changes have you implemented to maximize the conversion of heavy feeds and increase the amount of resid we can process without running into our regenerator limits and increasing dry gas production?

Considering the stated goals and constraints, particularly being limited by regenerator temperature and coke-burning capacity, it will be necessary to reduce delta coke without significantly increasing the reactor heat demand.
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(2016) Question 20: When is it appropriate to neutralize austenitic stainless-steel equipment to protect against stress corrosion cracking (SCC)? What neutralization procedures and methodologies do you recommend?

Austenitic stainless steels (200-and 300-series steel) are the most common type of stainless steels. Austenite refers specifically to the geometry of the steel (face-centered cubic crystal). These types of steel are most typically recognized as non-magnetic. Austenitic steels are widely used in the industry because they have very desirable mechanical properties. Their austenitic structure is very tough and ductile down to absolute zero. They also do not lose their strength at elevated temperatures as rapidly as ferritic iron base alloys.
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(2016) Question 21: What programs or systems do you employ to monitor hydrotreater furnaces and prevent tube failures and loss of containment? Can you share your experiences using technologies to implement online temperature monitoring of tube skin temperatures?

In nearly all hydroprocessing heaters, MPC has installed tubeskin thermocouples in order to provide continuous monitoring of tube metal temperatures to the DCS (distributed control system) operator. These thermocouples are strategically located in the heater at the areas with the highest estimated maximum heat flux.
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(2016) Question 22: Describe your strategies for optimizing the pretreat and cracking catalyst cycles. How does this strategy vary when operating between maximum naphtha and maximum distillate modes? How does this impact catalyst selection for the next cycle?

Marathon Petroleum Company has adopted the philosophy of optimizing the hydrotreater and hydrocracking catalyst together as one unit. We do not measure nitrogen slip from the hydrotreater section, but rather allow the hydrocracker apparent conversion dictate adjustments to the pretreat section.
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(2016) Question 23: How do you operate mid-distillate selective recycle hydrocracking units to generate more naphtha while minimizing fuel gas/liquefied petroleum gas without catalyst replacement?

Maintaining flexibility to make gasoline versus ULSD (ultra-low sulfur diesel) is very important to most refiners today due to the volatile nature of the market. Understanding the economic goals of your process unit and building in the flexibility through your catalyst selection process is the best way to set up your process for flexibility in the coming run.
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(2016) Question 70: What is your method for measuring naphthenic acid [TAN (total acid number)] in FCC feed? Is this method affected by VABP (volume average boiling point) or Concarbon (Conradson carbon) content? Do you have data that validates an appropriate integrity operating window (IOW) trigger level? If above the trigger level, what is your recommended corrective action (extra inspection, change crude/slate, etc.)?

In terms of TAN number, we typically recommend the standard test method UOP 565, which can be found through the ASTM (American Society for Testing and Materials) website.
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(2016) Question 71: In your experience, what factors affect NOx emissions for a partial-burn FCC with a CO boiler? How do you achieve 50 ppm CO emissions while simultaneously minimizing NOx emissions through the stack?

Combustor-or incinerator-style CO boilers can produce lower NOx emissions than direct burning CO boilers (COBs). COBs with cold planes where the CO is combusted (package boilers, as an example) require high firing rates to combust the CO to acceptable levels, thereby increasing the liberation and NOx contribution.
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(2016) Question 72: Recent drone technology advancements have enabled refiners and contractors to improve the efficiency of maintenance and inspection activities. With this, how are your hot work permits and general safety policies evolving to sustain adequate asset and personnel protection at all times? For instance, what additional safety permits or considerations would apply for drone use and aerial inspections?

In June 2016, the Federal Aviation Administration (FAA)announced that it had finalized the first operational rules for routine commercial use of small, unmanned aircraft systems (UASs) including “drones”. According to industry estimates, the rule could generate more than $82 billion for the U.S. economy and create more than 100,000 new jobs over the next 10 years.
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(2016) Question 73: What criteria do you use to justify sea-less pumps in place of conventional double-seal pumps in LPG services? What are the operational and reliability issues associated with these types of seal-less pumps?

Seal-less pumps can be either mag drive or canned motor. Seal-less pumps are now commonly used all over the refinery and petrochemical industries. The U.S.is quite a bit behind Europe in the use of seal-less pumps. Europe has been specifying seal-less for multiple services since the mid-1980s.
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