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(2015) Question 70: With environmental regulations becoming more stringent on FCC stack emissions, what are your available options to achieve the required level of SOx (sulfur oxide) and NOx (nitrogen oxide) emissions?

From both the SOx and NOx perspective, there is a cat feed hydrotreater that will reduce both your sulfur and nitrogen compounds in the feed to your cat cracker, which will produce lower SOx and NOx emissions. It will reduce your metals in the feed and increase the hydrogen content of the feed, which will improve FCC unit conversion.
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(2015) Question 71: Describe your practices for minimizing flaring and flue gas emissions during startup, shutdown, and malfunction operations?

Our Marathon FCCs all have a flareless startup procedure, but the type of equipment we have at our different FCCs varies somewhat. I pulled together an overview of what we have at our different plants and some licensor recommendations I learned through discussions I have had with them. I think we all agree that it makes sense, from a financial standpoint, to recover that material enough, whether or not the environmental stance is compelling us. It is just a part of being a good neighbor to the community in which we operate. 
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(2015) Question 73: Octane may become an issue as refiners increase severity on the FCC gasoline post-treatment units. What are your options available to address octane debits?

When you want to reduce the sulfur in gasoline, one of the first options you can do is undercut the gasoline. The sulfur distribution in gasoline is typically exponential. If you reduce the cutpoint of your gasoline, you will reduce the amount of sulfur in your gasoline. Sulfur exhibits an exponential distribution.
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(2015) Question 74: For a unit targeting low vapor pressure gasoline, which variables have the greatest impact on isopentane production?

While the question asks specifically about isopentane production, other C5 hydrocarbons also have significant vapor pressure. Isopentane has a Reid Vapor Pressure (RVP) of 20 psi (pounds per square inch); n-pentane has an RVP of 16 psi; and, the C5 olefins have RVPs between 14 and 26 psi9. For refineries desiring to minimize RVP, it is also important to minimize the quantity of C4s in the gasoline pool since C4s have even higher vapor pressures than C5s. 
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(2015) Question 76: What has been your experience with respect to FCC flue gas analyzers using tunable diode lasers or alternatives? Any specific advantages of tunable diode laser (TDL) analyzers with respect to installation, operational service requirements, and/or reliability?

MPC does not have any TDL analyzers in FCC flue gas service. However, we do have a few installed-on process heaters that are used to measure O2, and we are happy with their performance. In FCC flue gas service, MPC has one unit that utilizes an extractive system.
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(2015) Question 77: When relying primarily on FCC feed pretreating to meet FCC gasoline sulfur specifications (current or future Tier 3), how do you manage feed pretreater outages?

Marathon relies on feed pretreating for three of our FCCs, which will all continue post-Tier 3 regulation implementation. Looking at the difference between Tier 2 and Tier 3, we see that when the annual average ppm in gasoline goes down from 30 to 10, the maximum per gallon, I believe, does not change from 80.
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(2015) Question 78: Under what conditions do gasoline sulfur reduction additives and catalysts reduce sulfur in gasoline, and by how much? What is the lowest gasoline sulfur level for which the gasoline sulfur reduction products are effective? At this gasoline sulfur level, please quantify the gasoline sulfur reduction and the amount of additive/catalyst required.

That is a very long breath of a question. [Laughter] I will summarize some of the Marathon’s findings on gasoline sulfur reduction additives. We have done a lot of testing in our pilot plant in the past. Some of that has already been presented.
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(2015) Question 79: For units that have experienced elevated losses leading to coarse inventory, what options exist to improve catalyst properties during turnaround? Describe your experience with purchasing external or classifying spent catalyst.

We get fixed on how much 0-to-40 micron catalyst is in the inventory. You need 10% to run the unit well. And as Bob Flanders used to say, “Purgatory was trying to run a Model IV with less than 10% fines in it.” What I would suggest is certainly nothing smaller than 20 microns.
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