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(2013) Question 80: We have coke deposits in the plenum chamber and vapor line and are concerned the deposits may spall off or ignite during refractory dryout. What precautions should be taken to avoid re-igniting these coke deposits during the dryout?

We prevent hot air from entering into the reactor system during the regenerator dryout. Subsequently, we will use initial catalyst circulation for the reactor side dryout. Prior to lighting the DFAH (direct fire air heater) for the regenerator refractory dryout, we will introduce dry steam into the reactor, feed distributors, reactor riser, reactor dome, and stripper section.
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(2013) Question 81: How do CO (carbon monoxide) and NOx (nitrogen oxide) emissions change when you operate at low regenerator temperatures? What can be done to mitigate any increases?

I will initially address this question from a CO standpoint and then discuss the NOx. CO emissions typically increase if the regenerator falls below a certain temperature threshold. That temperature threshold will vary based on your regenerator configuration and definitely on the type of air distribution.
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(2013) Question 82: For those operating units with electrostatic precipitators (ESPs), share your experience with using SOx (sulfur oxide) reduction additives and their impact on: 1) ESP performance, 2) stack opacity, and 3) filterable solids mass.

We have two ESPs in our system. One of them is on a unit currently using less than 2.0% of SOx additive. We have not seen any impact at all on performance, opacity, or filterable solids. The other ESP went through a retrofit within the past four years, going from a smaller, older version of an ESP to a larger ESP with more modern technology.
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(2013) Question 84: What are the commercial experiences with low rare earth and zero rare earth SOx reduction additives? What are the incentives to return to traditional products now that rare earth prices have returned to historical levels?

During the run-up in the cost of rare earth in 2011, Grace embarked on an expedited and extensive R&D (research and development) program to develop future generations of our Super DeSOx® additive to cut the rare earth content and try to minimize the financial impact that the ever-increasing cost of rare earth had on our customers’ cost of SOx compliance.
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(2013) Question 85: What are the advantages and disadvantages of catalyst mesoporosity [100 to 600 ǻngström (Å) diameter pores] in VGO (vacuum gas oil) operations?

When talking about catalyst mesoporosity, we are referring to the matrix contribution, especially the 100 to 600 ǻngström pores found in the catalyst matrix activity. Catalyst matrix activity is really important, particularly in the Type I cracking depicted here, in the mix zone of the riser where the mix zone can be on the order of 1100°F.
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(2013) Question 86: What are the advantages and disadvantages of pre-blending FCC additives with FCC catalyst? What is the experience with incorporating FCC additive functionality into the catalyst particles?

Certainly, the obvious advantage of pre-blending additives with your base catalyst is improving your logistics and not handling totes. Another advantage is in not needing an additive loader that you have to maintain. Additionally, pre-blending avoids the possibility of human error in the additive injection process. There are significant drawbacks to doing this as well.
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(2013) Question 87: The operation of a resid FCC can be challenging as more of its feed is hydrotreated to meet ULSG and ULSD specifications. What changes can be made to improve its operation?

For the purpose of this answer, we will look at this as a resid cat cracker that would have a catalyst cooler or be in a two-stage operation. Any increase in feed hydrotreating which increases the portion of hydrotreated feed, or an increase in hydrotreating severity, will obviously improve the feed quality.
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