One of the most frustrating situations to endure is the slow cooldown of a reactor (or series of reactors) when shutting down a hydrocracker, hydrotreater, or renewable feed unit. It often seems that the entire refinery is watching the reactor cool, especially as reactor temperatures drop below 200⁰F. This blog article will cover ways to […]
Hydroprocessing Heat Exchanger Fouling due to Di-olefin Polymerization Over the past few months, I have received several questions about heat exchanger fouling in hydrotreaters due to polymerization of di-olefins and/or other gum precursors in the feed. I have seen plenty of heat exchangers foul in my career due to this mechanism and have found a […]
This month we’ll continue our discussion of emergency procedures for hydroprocessing units with a discussion of hazards and procedures for minor/major loss of containment incidents. Incidents related to emergency depressuring valves in hydroprocessing units Incident 1 A VGO hydrotreater suffered a backflow incident on the wash water piping resulting in the overpressure and rupture […]
“It can’t happen!” “Our control systems have redundancies that won’t allow us to lose view!” “If we lose view, we’ll just move to the field control room and run the unit.” The comments above are what I have heard in the past when discussing emergency procedures for loss of view and loss of control on […]
Consider the intrinsic risks of a reactor feed furnace in a hydrotreater or hydrocracker: On the outside of the furnace tube, we have intense fire from the burners On the inside of the furnace tube, we have high-pressure H2 or a H2/oil mix where the oil is above its autoignition temperature, and the vapor contains […]
The potential formation of nickel carbonyl is a hazard for all hydroprocessing units – both hydrocrackers and hydrotreaters. Fortunately, there have not been a lot of incidents in the refining industry related to nickel carbonyl, but there have been fatalities due to nickel carbonyl exposure. This blog will cover the risks of nickel carbonyl exposure, […]
A topic that frequently comes up in consultation is how to posture a hydrotreater or hydrocracker when a short, temporary shutdown is needed (with no catalyst change). These short outages can last from a few hours to a few weeks and sometimes, rarely, a few months. Often, the biggest choice in how to posture a […]
A quantitative method for selecting emergency actions could prevent hydrocracker reactor temperature excursion and runaway while avoiding flaring. Recently published article in PTQ Q3 2023 Issue (digitalrefining.com). An excerpt from the article is below… Refiners use multiple emergency actions to react to a reactor temperature excursion or reactor runaway in a hydrocracking unit. Automatic depressuring […]
I had multiple requests to discuss how to evaluate purchased feedstocks for hydroprocessing units. As always, I’ll present some ideas and welcome further comments and thoughts. Jack be nimble, Jack be quick! In my background, the question of whether to purchase a feedstock for a hydroprocessing unit comes up with very little notice and sometimes […]
This is the third of 3 articles discussing relief issues for Hydroprocessing Units. Last month we discussed Separator Blow-through. As discussed, the five main lessons from that article are: Relief valves on low-pressure separators must be designed for vapor blow-through The design vapor blow-through rate must consider all potentially open level-control valves and bypass valves […]
