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(2015) Question 32: What is your suggested minimum temperature required to achieve adequate metals removal in the demetalization (demet) catalyst to protect primary treating catalyst in FCC and hydrocracker pretreaters?

The suggested minimum reactor temperature required for adequate metals removal is going to be metals specific. For silicon, the temperature is definitely greater than 570°F; and for nickel and vanadium, we suggest greater than 600°F. Now higher reactor temperatures may be required for adequate removal, depending on the space velocity through the metal-strapping catalyst and whether or not there may be a tolerance issue with the primary treating catalyst.
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(2015) Question 33: Phosphorus-based chemicals are used to neutralize naphthenic acids. Drilling and completion fluids also can contain phosphorus, so it may be in crude oil. What are your Best Practices to protect active hydrotreating catalyst from phosphorus poisoning?

I am going to give a little background on phosphorous poisoning and then share one specific example we have seen in one of our refinery units. First of all, phosphorus is a strong catalyst poison. In our course materials, we say that 1% phosphorous on catalyst will reduce the activity by 50%.
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(2015) Question 34: Hydroprocessing reactor pressure drop can increase due to feed particulates, corrosion by-products and polymerization reactions. How can bed design and loading method be optimized to avoid pressure drop limiting the cycle length or throughput?

There are a lot of approaches to helping out with pressure drop problems in a reactor, and I will go through them. We use all of these at Phillips 66. I will start at the top. There are particulate catching trays. These are relatively new. We have had limited use with these, although we think they have been fairly successful.
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(2015) Question 35: What important parameters do you consider in designing a post-treat bed for a hydrocracker? What are the advantages and disadvantages between Type I and Type II catalyst when used as a post-treat bed in a hydrocracker?

The post-treat bed is generally positioned at the bottom of the reactor in a hydrocracking reactor, and its main purpose is to remove sulfur compounds that have recombined with the organic compounds coming out of the reactor. Usually, it is a function of olefins that are generated in a hydrocracking catalyst.
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(2015) Question 36: What has been your experience regarding selectivity and activity when using regenerated hydrocracking catalysts versus fresh catalysts? How do results vary with catalyst type, unit objectives, and conversion targets?

There are well-established track records for regeneration and the reuse of spent hydrocracking catalysts, depending on service history, catalyst type, and conditions in which the catalyst was recovered. These catalysts can be returned to fresh or near-fresh performance, in most cases, and often come back basically equivalent to fresh.
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(2015) Question 37: What are some of your strategies for managing as oil streams during outages of conversion units for refiners with vacuum gas oil hydrocracking and FCC units?

Obviously, the answer to this question is very site-specific depending on different options available based on refinery location and configuration. There are a couple of general options, and I will give one example. If you have an outage of a VGO processing unit in your refinery, one option would be internal processing.
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(2015) Question 39: In terms of hydrocracking, what different definitions of conversion do you use?

Fundamentally, conversion is probably the most common operating target used for hydrocracking units. Conversion provides us with a measure of the amount of reaction or the amount of work that is accomplished in the unit. The simplest definition for conversion is typically this equation for gross conversion: a hundred times the fresh feed minus the unconverted oil, divided by the fresh feed; unconverted oil being the recovered fractionator bottoms.
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(2015) Question 40: What has been your experience regarding time required for hydrocracking operations to recover from temporary poisoning by organic nitrogen in the feed? What operational changes can be made to reduce the chance of permanent deactivation?

It can be a short duration, one to two days, or potentially longer, 21 to 30 days, depending on the response to the events and dependent upon the amount of higher severity feed, higher nitrogen, and higher aromatic content feed. It could be a shorter duration if quickly caught and corrected.
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(2015) Question 41: How do you manage operating flexibility to maximize profits in a changing margin environment during a hydrocracker cycle?

Frequently, market conditions will reward the refineries that have a little flexibility in shifting their product yields among conversion units. We try to do that where that flexibility exists. For a hydrocracker, a primary knob is just overall conversion. Decreasing conversion will enhance distillate yield, increasing conversion, gasoline yield.
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