Q&A

(2013) Question 42: Occasionally we make off-color jet (pink, blue, or green). What are the causes, and what can be done to correct this?

The question was specific to off-color jet, but we can have other off-color material. We have seen red, yellow, green, and brown. Most typically, the yellow and green tend to be associated with the lighter products, red and brown with the heavier ones. But again, you can get various colors throughout the spectrum.

(2013) Question 43: Can FCCU feed pre-treatment achieve the new Tier 3 gasoline sulfur targets without post-gasoline treatment? What criteria are used to select the optimal combination of pre-treatment and post-treatment severities to meet the Tier 3 objectives?

For Tier 3 gasoline, the anticipated average of 10 ppm sulfur will be required by 2017. In order to understand what will be needed to meet those specs, you will have to do a review of a number of factors that contribute to the sulfur, including understanding your crude diet and the material that is actually going into the gasoline pool, as well as blend components.

(2013) Question 44: What are refiner’s practices or procedures to remove catalyst from a reactor when the catalyst will not free flow dump? What is the industry's experience with hydro drilling for removal of non-free-flow catalyst from fixed-bed units?

We typically vacuum out catalyst in an inert atmosphere if the reactors do not free-flow dump. We also wet dump some of our reactors, which involves vacuuming out the catalyst after removing the water. For people who are involved in turnaround planning, unloading rates for free-flowing catalyst are approximately 200 cubic feet of catalyst per hour.

(2013) Question 45: What are the procedures/rules governing the transportation and disposal of catalyst contaminated with arsenic, mercury, barium, or other heavy metals? Are there maximum limits for any of these?

The spent catalyst needs to be shipped offsite and sent for metals reclamation or disposal. If it is going for disposal, it will have to be characterized to determine if 1) it is a hazardous waste, which it is most of the time, and 2) it meets the applicable Land Disposal Restrictions (LDRs). It would have to be treated, as part of disposal, to meet the LDRs.

(2013) Question 46: What are the main considerations in converting a fuel hydrocracker into lubes services in terms of equipment modifications and catalyst selection?

The conversion of a fuel hydrocracker to a lube hydrocracker mainly depends upon the product quality requirements and unit constraints. If you are producing lube-based stock as your main product, then the operating parameter needs to be examined in detail.

(2013) Question 47: What evaluations are required for hydrocracking units to increase conversion due to processing heavier feedstocks?

Pilot plant studies should be done to evaluate catalyst performance with new proposed feeds. If you are planning to make revisions to your unit, you certainly want to consider catalytic changes, perhaps more selective to diesel or gasoline. Your operating cycle could possibly decrease or increase with conversion, depending on which way you are tending to go.

(2013) Question 48: What are the typical guidelines for reactor loading if the decision is to not fully load with catalyst? Is it acceptable to short load a reactor, and what are the recommended minimum and maximum distances below the inlet distributor?

First of all, it is a bit unclear why one would want to short-load the reactors. Can it be done? Yes, especially if it is a gas-phased operation. If it is a mixed-phase operation, then it probably could become an issue.

(2013) Question 49: What are the criteria for levelness during dense loading of a catalyst bed? What are the preferred monitoring techniques, and what is the best approached to correct an uneven bed profile if it is detected?

Really, it is not so much that you want to maintain a definite level bed, but what comes with that is making sure you are truly loading your reactor correctly and that you have an even distribution of densities through your entire bed. We also recommend that you check loading densities at some prearranged interval. Initially, it may be 10 or 15% of the start-of-run and then every 25% throughout the load until you are finished.

(2013) Question 50: What are the technology evaluations and engineering studies required for revamping a diesel hydrotreating unit to substantially increase throughput?

In any major revamp of throughput for a DHT (distillate hydrotreater), establishing a realistic design basis and engineering certainly never really exists. The idea is to look not just to the point but at deviations and feedstock properties, expected changes in compositions, and past history of contaminants.

(2013) Question 51: For hydroprocessing reactor modifications that involve the addition or removal of distribution trays and flexible thermocouples, what is your Best Practice for welding support rings or support lugs on a reactor wall? What is your Best Practice for removal of these items when they are no longer required?

When you are trying to remove the attachments from the reactor, do not touch them unless it interferes with your process flow, catalyst loading, or internal installation or access. When the rings are welded to the support rigs, remove the rings and leave the lugs in its place.

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