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(2017) Question 51: Can you comment on the safety aspects of placing catalyst in a standpipe to help isolate one vessel from the other? Does the existence of catalyst in a standpipe create a ‘seal’?

I would like to mention that we will have a P&P tomorrow on this topic, so I will try to keep my answer short. It is assumed that this question relates to using the slide or plug valve to form a seal between the regenerator and the reactor during shutdowns. I would like to point out that this is a standard practice in an FCC as there is really no other option; and for the most part, it does work. 
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(2017) Question 52: What challenges do you face for implementing safety-instrumented systems that result in closure of the FCC slide valves?

Systems are designed to meet a specific safety integrity level (SIL). Each operating company has a risk-based matrix specific to the company or site. This matrix has severity on one axis and probability on the other axis. High severity and high probability score the highest. Based on this ranking system, the company sets the SIL rating at SIL 1, 2, or 3. SIL 1 and 2 are the most commonly found in typical refinery processes.
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(2017) Question 54: What recent innovations have you made to instrumentation that has application in FCC units?

For level measurement, guided-wave radar level instruments have been gaining popularity and been successfully applied in numerous services, especially for interface levels. Nuclear-type level instruments have been more or less accepted in other processing units in refineries and have made their way into the FCCU for severe services, such as main fractionator bottoms level, and for hopper levels.
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(2017) Question 59: We are reformulating our FCCU catalyst. What are your Best Practices to post-audit the catalyst change?

Preplanning is an important part of ensuring that the catalyst reformulation and post-audit are successful. Before the catalyst trial begins, it is important to define catalyst objectives and establish a clear evaluation plan on how these objectives will be monitored and evaluated for the trial. Sample and data collection guidelines and establishing a good base case should be done before the trial. It is critical that the samples and processed data needed to monitor the reformulation are routinely collected before and during the trial.
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(2017) Question 60: With today’s current variety of new crudes, synthetic crudes, tight oils, bio-based streams, opportunity feeds, etc. that find their way to the FCCU, what new metal contaminants (excluding nickel, vanadium, iron, and sodium) do you see that impact catalyst and FCC performance?

In addition to the “standard” contaminants of nickel, vanadium, iron, and sodium, there are a variety of other feed contaminants that can impact FCC performance. For example, tight oils (also known as shale oils) can contain high levels of potassium, magnesium and calcium in addition to the iron normally found in them8. While bio-based feedstocks are not yet widely processed in commercial units, they would be expected to contain higher levels of calcium, sodium, magnesium, and potassium than conventional feed sources since these elements all play an important role in biological systems. High levels of phosphorous have been found on synthetic crudes.
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(2017) Question 61: When performing catalyst evaluations and considering catalyst resistance to attrition about particulate matter (PM) emission requirements, what new or advanced attrition testing methods are you using to predict the performance of the new catalyst system? Are there third parties who can conduct a standard testing regime to multiple catalyst systems?

A number of operating factors influence catalyst losses from the regenerator that can lead to particulate matter (PM) emissions. These factors include: the number of fines present in the freshly added catalyst, the number of fines generated in the unit, the amount of catalyst transport to the cyclones by entrainment, and the cyclone performance.
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(2017) Question 62: Do you know of factors that are likely to lead to deposit formation on power recovery turbine blades? Is there anything that can be done to prevent these deposits from laying down on the blades? Once the deposits have been formed, what are the consequences and is there any way to remove the deposits online?

Deposit formation is usually linked to catalyst depositing on the turbine blades. The deposits are mostly a function of catalyst loading of the inlet flue gas. An increase in catalyst loading could be due to several factors, including performance of the third-stage separator, loss in cyclone efficiency, change in catalyst attrition properties, excess fines in fresh catalyst, an increase in fresh catalyst additions, and/or an increase in flue gas rates due to higher air rates.
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(2017) Question 63: Please explain the phenomenon known as “coke ratcheting” in the FCC reactor where equipment exposed to coking services elongates over time and heat cycles. Please provide details of actual examples of where this occurred and the impact to equipment operations and reliability.

Coke ratcheting occurs in hot-wall reactor/riser systems. When the system is at operating temperature, the parent metal expands more than the hex mesh lining does. This expansion creates small voids between the hex mesh biscuits that are large enough for hydrocarbon vapors to enter and come in contact with the parent metal. Coke forms in these voids.
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(2017) Question 64: What are the risks and negative factors you see associated with processing slurry oil, either as slurry separator backwash or recycle, in the FCC reactor?

Slurry recycle and slurry separator backwash are two very different processes with varying objectives and negative impacts. Slurry recycle is typically done intentionally for the purpose of increasing coke make to help a unit that is short on heat balance. Such units are usually processing very light, sweet feeds and are unable to meet their processing objectives without additional heat input. Slurry separator backwash is required to remove the collected solids from the slurry filter/separator to ensure their efficient operation. 
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