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(2016) Question 8: Do you have experience starting up an isomerization unit (an alumina chloride catalyst type) without first acidizing the reactor loop? What was the impact on catalyst activity?

Honeywell UOP strongly recommends that acidizing of the reactor circuit should be included in the commissioning and startup of a new grassroots or revamped Penex™ or of Butamer™ units (isomerization units with chlorided alumina catalyst). If not, the consequence can be a significant amount of catalyst deactivation, as well as possible corrosion in the reactor section of the unit. A recent experience in which the customer elected to NOT complete the dry out and acidizing of a new reactor section resulted in an estimated deactivation of 60 to 85% of the new catalyst load.
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(2016) Question 9: Describe your experience and application of advanced separation techniques, such as DWCs (dividing-wall columns), to reduce capital investment and operating expense.

At Valero, we actually have several dividing-wall column applications. We have four in aromatics recovery service and one in a sat(saturated)gas plant service. The towers in aromatic service have been in operation between three and six years, and the tower in the sat gas service has been in operation since early 2016. All towers are meeting their design expectations. The dividing -wall towers have several advantages relative to the traditional sequential column designs.
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(2016) Question 12: What operating strategies do you employ to successfully regenerate catalyst in a continuous catalyst regeneration (CCR) unit with a carbon content in excess of 10 wt%?

The burn zone in a Honeywell UOP Platforming™ CCR Regenerator is designed for operation at 5 wt.% carbon on catalyst or about 5.25 wt.% coke at the design catalyst circulation rate. We find that most units can operate normally at coke levels 40% above the design (about 7.4 wt.% coke) and some at even higher levels of coke.
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(2018) Question 4: What are the requirements for a unit depressurization valve in isom unit using a chlorided alumina catalyst based? Do you require the depressurization valve to be operable from the console and/or emergency shutdown device (ESD) panel?

Axens recommends that in cases of emergency depressurization of the reactor circuit, the circuit fluid is depressurized into the product stabilizer with the light gases still being treated in the off-gas caustic scrubber before being sent to flare.
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(2018) Question 6: What are the catalyst or design considerations that you employ to repurpose isom units for other services, or to repurpose another type of unit into an isom unit?

With increasing quantities of lower octane naphthas reaching the gasoline pool and potential for higher octane demand in the finished stocks, the octane boost from isomerization units has grown in importance. While the installation of new units is ideal, many refineries have been looking at utilizing idled units or converting existing units to isomerization type operation.
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(2010) Question 38: What measurements and criteria do you use to decide when to change your gas and liquid chloride absorber material? How do you determine the selection of absorber material?

For both gas and liquid service, Chevron monitors the inlet HCL/Total Chloride and replaces the adsorbent/molecular sieve based on material balance loading of chloride on the adsorber media. Chevron does monitor adsorbent outlet HCL/Total Chlorides, but as a best practice will change the adsorbent material before vendor maximum loading if breakthrough has not occurred.
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(2010) Question 39: With lower severity requirements due to ethanol blending and corresponding reduced coke make in the reformer, what changes are you making in regards to reformer operation? What opportunities does this evolution present for both CCR and semi-regen units?

Increased ethanol blending has reduced the severity of the reformers on average 2 octane numbers. This has increased reformate yield and decreased hydrogen production. Although the octane boost realized by ethanol blending reduces overall pool octane requirements, minimum reformer severity may be dictated by octane requirements of premium gasoline grades, or by refinery hydrogen requirements.
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(2010) Question 40: Has anyone experienced high chloride levels in off gases from the lock hopper of a pressurized regenerator? What are the consequences of the high levels (i.e. fouled burner tips)? What are ways to mitigate the problem?

Marathon has not experienced any high hydrogen chloride concentrations in Lock Hopper off gases from the two CycleMax regenerators that we operate. We have also not experienced problems with fouled burner tips due to high hydrogen chloride in the fuel gas to a heater.
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