Q&A

(2012) Question 89: With the increase in rare earth costs, many units have decreased the rare earth oxide (REO) content or used rare earth substitutes in their FCC catalyst. What is your experience with these in terms of activity maintenance, delta coke, conversion, attrition, and yield selectivity's? How have operating conditions changed?

Rare earth stabilizes zeolite and increases hydrogen transfer. Reducing the rare earth on zeolite will decrease the catalyst activity at the same zeolite content and matrix activity.

(2012) Question 90: Can ZSM-5 be used to make propylene from high metal resid feeds? What is the effect of nickel and vanadium on this kind of operation?

ZSM-5 usage is widely used in FCC units trying to maximize propylene. ZSM-5 usage is just as popular in resid units as it is with gas oil units. We have seen high propylene yield units, resid units with feeds greater than 6 Conradson carbon residue, and e-cats that exceed 10,000 ppm nickel plus vanadium.

(2012) Question 91: What FCC turnaround intervals are refiners achieving for units that do not take mini turnarounds? Do longer intervals mean lower reliability between turnarounds?

Most of BP’s units are now transitioning from about a four-year turnaround cycle to a five-year. We have some units already running five years between turnaround cycles without necessarily showing evidence of higher wear and tear.

(2012) Question 92: Describe the turnaround scope of work for the combustion air blower. Does it differ for units with turbo expanders? Do you work on the air blower every turnaround? Is this work performed by a general turnaround contractor or by the manufacturer? How often does this work become critical path?

Most sites replace the internals of the expander during every turnaround. The stator veins are thoroughly inspected and replaced on as-needed basis.

(2012) Question 93: How do you manage regenerator cyclone life to ensure that you reach target turnaround intervals? Do you consider superficial velocity, inlet velocity, inlet loading, outlet velocity, etc.?

At KBR, we specify design parameters that will allow the operator to achieve extended regenerator cyclone life for several turnaround intervals. Based on our experience, it was shown that most cyclone problems are attributed to operating above the maximum recommended velocities. KBR recommends that Operations maintain a cyclone inlet velocity below 70 fps and 80 fps for the first- and second-stage cyclones respectively.

(2012) Question 94: What is your experience using specially designed automated isolation valves on the reactor overhead line for your de-blinding operation during the start-up of the FCCU? Will they dependably provide positive isolation after being in operation? How did you justify the installation cost (e.g., safety and economics)?

We have quite a few units that use valves in the vapor line and others with just simple blocked valves in that service. Two more units now have a newer style: a double disc valve which relies, in part, on a steam purge to provide positive isolation. Because that valve was very successful, two more valves are going to be installed soon.

(2012) Question 95: What is the recommended Best Practice regarding the design of catalyst loading and unloading lines with respect to metallurgy, size, run lengths, bends/Ts, cleanout connections, etc.?

KBR’s Best Practice is to fabricate the main catalyst loading and unloading lines with carbon steel. To protect the carbon steel lines against elevated regenerator temperatures, KBR recommends that Operations personnel only de-inventory the converter after the catalyst has been cooled below 650°F.

(2012) Question 96: What is the CO boiler start-up and shutdown sequence with respect to the FCCU start-up and shutdown timing? What are the reasons for this sequence?

As I mentioned briefly in an earlier question, most of our FCCs with CO boilers start-up with the CO boilers bypassed. If we run partial-burn on any of these FCCs, we tend to start-up in full-burn at reduced rates. Once the feed is in the unit and considered stable, most sites will cut into their CO boiler with the process flow.

(2012) Question 97: What equipment do you employ to help eliminate ESP hopper and downcomer plugging with catalyst fines? What additional operating practices are used? What type of level detectors are in use on the ESP hoppers and/or catalyst storage silos? Are there any new level detection technologies that could be applied, perhaps from coke drum measurement detectors?

Our main problem with the ESP is fines accumulation in both the ESP hoppers and the transfer line from the hoppers to the fine's storage bin. We have incorporated some design improvements that have helped us minimize, but not completely eliminate, the main problems of condensation in the system and plugging.

(2012) Question 98: What is your experience with the use of ammonia or steam in the FCC flue gas line in order to improve the operation of the ESP? Please comment on system configuration and operational issues

We have extensive experience with the use of ammonia in the FCC flue gas line in order to improve the conductivity of the particles and improve the operation of the ESP. We inject ammonia at the target level of 10 parts per million or less.

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