This is a question that comes up relatively frequently and is an area where Grace has done extensive R&D work and publication. I will summarize a longer answer that appears in the Answer Book. So please refer to that response, as well as to some of the publications Grace has in the trade magazines.

First of all, acetone is hard to detect by itself. It requires a special column in GC (gas chromatography) to pick up the polar species. Normal GC just picks up the regular hydrocarbons. We have seen acetone concentration in the C4 stream, butane and butylene (or BB, to be specific) as high as 800 ppm. In the same unit, we also measured average acetone concentration of 300 ppm over the course of the same month with values as low as 50 ppm.

Some light hydrocarbons can be found in the flue gas in very small quantities, depending on the unit. The factors that contribute to light hydrocarbons in the flue gas are poor stripping in the reactor and maldistribution of the spent catalyst and very high catalyst circulation rates. Several industry trends have pushed the FCC units to operate in these undesirable regimes.

At Valero, we have a centralized group in the Planning & Economics area that is responsible for the kinetic modeling for all of the major process units. The primary driver behind the kinetic models at Valero is to get good data into our LP (linear program) models.

A review of our clients worldwide did not find any client that was blending any FCC product with just sweetening into jet. Limiting issues would be olefins (gum formation) and aromatic and potentially naphthalene content of unhydrotreated FCC jet boiling range components.

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.

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.

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.

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.

Nitrates and nitrites are inevitable byproducts from the removal of NOx from FCC flue gas. Obviously, one way to lower this nitrate concentration going into the purge water is to reduce the NOx in the flue gas, which we discussed a couple of questions ago.