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(2010) Question 44: Contaminants in aromatics extraction unit feeds such as chlorides and oxygen are difficult to measure, and can lead to operational issues (such as fouling / corrosion / erosion, etc) in the extraction unit. In your experience, what are the primary effects of these contaminants, and how can one manage these impacts?

Most of Marathon’s experiences with contaminants that affect solvent quality are with oxygen. Oxygen can enter the unit from solvent storage, feed, and re-run tanks. Any vessel operating under a vacuum can also be source of oxygen. Most of our issues with corrosion have occurred in the stripper and recovery column reboilers.
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(2010) Question 46: What is the panel's experience with in-line blending and in-line certification? What are the main differences between in-line blending and certification?

For clarity, a common definition of “in-line blending” is required. Marathon defines in-line blending as a system that pumps multiple blend components from individual tanks, which are typically “live” (either receiving or capable of receiving components from a process unit or pipeline delivery) into a header. The header generally contains static mixing to ensure homogeneity of the blend.
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(2008) Question 90: What determines the minimum feedrate for a fixed bed reformer? What process indicators would tell you that the feedrate is too low?

Question 90: What determines the minimum feedrate for a fixed bed reformer? What process indicators would tell you that the feedrate is too low? Rick Grubb (Chevron USA) Besides mechanical limitations, such as pump capacities, flowmeter ranges, control valve sizes, etc., the process factors that determine the minimum feed rate of a fixed-bed reformer are: •Flow distribution in the reactors •Heat of reaction dissipation in reactors •Flow distribution in furnaces •Phase separation in exchangers
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(2008) Question 92: What criteria do you use to determine end of run (EOR) catalyst life for a CCR? How many regeneration cycles have you achieved between catalyst replacements?

Question 92: What criteria do you use to determine end of run (EOR) catalyst life for a CCR? How many regeneration cycles have you achieved between catalyst replacements? Willie Morrissette/Joe Zmich (UOP LLC) There are a number of considerations in determining the End of Run for a catalyst cycle in CCR operations. Refinery economics are typically the ultimate factor used for determining when to replace CCR Reforming catalysts. The useful life of a CCR catalyst is impacted by the operation of the unit and is a function of the ability to maintain the proper metal and acid function of the catalyst as well as the condition of the catalyst base. UOP’s CCR PlatformingTM catalyst can achieve very long life because UOP reactor and regenerator operate at optimum conditions.
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(2008) Question 93: On a CCR, what causes the regenerator chlorination zone to plug off before the regeneration zone?

Question 93: On a CCR, what causes the regenerator chlorination zone to plug off before the regeneration zone? Ka Lok/Joe Zmich (UOP LLC) Assuming that the question relates to the inner screen of the chlorination zone of a UOP Atmospheric CCR regeneration section relative to the burn zone, the most likely cause of this is failing to operate the CCR regeneration section burn zone per the UOP General Operating Curve. If the catalyst circulation rate for given oxygen concentration exceeds the maximum indicated by the curve, it’s likely that catalyst with higher than desired coke will enter to the chlorination zone leading to catalyst damage. The damaged catalyst can be smaller and fracture into dust and chips in the chlorination zone leading to plugging of the chlorination zone screen. Some licensees have observed an increased slot width in the chlorination zone after a long time in operation. An increase in slot width increases the tendency of the screen to foul with catalyst chips or smaller diameter catalyst.
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(2008) Question 2: Do you re-evaluate your unit operating procedures at regular intervals? How often? What principles/standards are these procedures reviewed against?

Question 2: Do you re-evaluate your unit operating procedures at regular intervals? How often? What principles/standards are these procedures reviewed against? David Rapavi (HOVENSA) HOVENSA reviews and re-issues unit operating procedures in accordance with OSHA Standard 1910.119 paragraph (f)(3), which states “Operating procedures shall be reviewed as often as necessary to assure that they reflect current operating practice, including changes that result from changes in process chemicals, technology and equipment, and changes to facilities.
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