Q&A

(2019) Question 10: What causes metal-catalyzed coking (MCC) that obstructs catalyst circulation in CCR reformers? What actions do you take to mitigate MCC formation?

BILL KOSTKA (AXENS NORTH AMERICA)
Metal-catalyzed coke (MCC) formation typically occurs on 3d valence transition metals such as iron and nickel. Under CCR-like conditions of low hydrogen partial pressure (less than about 620 kpa), high temperature (more than about 480 °C) and low or stagnant flow

(2019) Question 11: Where are your liquid-phase chloride treaters installed for reforming units? What are the advantages of each location?

BILL KOSTKA (AXENS NORTH AMERICA)
Liquid-phase Cl treaters are typically used in three locations for reforming units.

Treating the unstabilzed reformate stream provides several advantages. The stream is heated upstream of the stabilizer column which ensures that any ammonium chloride is

(2008) Is your company planning to install modified HF acid capability (usage of the volatility suppressing additive)? What are the incentives for doing this? What alternatives have you considered?

In March 2006, in our continuing effort to support safe, reliable, and environmentally sound operation, we announced our plans to apply for a permit to independently initiate an alkylation process improvement project in our Philadelphia HF alkylation unit.

(2008) Question 70: How frequently do you have fires on reformer reactor flanges? What bolting techniques and gasket types do you use to prevent leaks? What other fixes, such as flange resurfacing, have you employed? Do you use steam ri

GRUBB (Chevron USA, Inc.) Chevron has had some experience with flange fires in the past, so I’ve consulted with Dave Reeves, our corporate expert and also our Best Practice that we’ve developed for this. I know that I said temporary fixes up on the slide, but it’s not really a temporary fix.

(2008) Question 86: The reformer’s feed properties can be affected when the refinery is maximizing refinery diesel yield. How do these changes to reformer feed affect performance with respect to C5+ yield, hydrogen production, cycle length, and economics?

NEWTON (Roddey Engineering Services, Inc.) As everyone knows, we’re not here to discuss how to make more gasoline; we’re here at the conference to learn how to make more diesel, so I just hope you people in here... But whenever you start to talk about maximizing diesel yield from most refineries, what you’re going to talk about is shifting the heavy end of the reformer feed to the diesel stream and so you lower your endpoint to the reformer.

(2008) Question 87: Iron contamination of CCR, cyclic, and semi-regen reformer catalyst is a common problem. What level of iron concentration typically justifies catalyst replacement due to poor catalyst performance?

METKA (Sunoco, Inc.) Typically, iron levels up to approximately 12,000 ppm can be tolerated before a change-out is required. Iron is a support modifier that can affect both the metal and acid sites. There is more of an impact on the acid sites, and iron can impede chloride pick-up and trap sulfur on the catalyst. Iron typically impacts the first reactor in a fixed-bed unit and is primarily a result of upstream corrosion in the naphtha hydrotreater.

(2008) Question 88: What is your experience with feed-side fouling on combined feed/effluent (CFE) exchangers? What is the foulant? How often do you clean them and what cleaning techniques do you use? On Texas Towers (vertical shell & tube exchangers), how do you extract the bundle from the shell if it gets stuck?

NEWTON (Roddey Engineering Services, Inc. Engineering) I’m just going to deal with Roddey Engineering’s experience. I know some people on the panel have different experiences. But as far as feed effluent exchangers go, and especially Texas Towers, we have seen significant fouling on all that we’ve dealt with. Pretty much every refinery that has one, they do not clean the tower.

(2019) Question 2: We have a Selective Hydrogeneration Units (SHU) unit that removes butadiene from the olefin feed to the alkylation unit. What is the typical concentration of hydrogen and light ends in the olefin product leaving the SHU? How do hydrogen and light ends affect alky operations?

THOMAS PORRITT (Chevron U.S.A)
A selective hydrogenation unit or SHU converts diolefins to olefins in a stream before it feeds an alkylation unit.

Below is a basic flow scheme.

Figure Q2 - 1 Selective Hydrogenation Unit Flow Scheme

The typical composition of non-condensable gases and light

(2019) Question 3: What is your experience with ball valves in feed and make-up gas drier circuits in ISOM Units? What strategies have you adopted for monitoring leaks, regular maintenance and achieving longer run length?

DAVINDER MITTAL (HPCL Mittal Energy)

The gas and liquid dryers perform important task of safeguarding the ISOM catalyst from water vapor and other impurities in the make-up hydrogen and hydrocarbon feed.
The dryer switching valves play an important role of directing the inlet/outlet gas streams

(2019) Question 4: What are your best practices for controlling caustic strength in an isomerization unit scrubber? How frequently is the caustic refreshed?

It is quite important to optimize PERC injection in feed as guided by technology supplier as otherwise the HCl concentration in off gas can go too high (normal range 1500 - 2500 ppm). This will lead to rapid depletion of caustic strength due to neutralization effect, thereby requiring frequent fresh caustic make-up.

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