Proactively Preventing Reactor Runaway Events

Proactively Preventing Reactor Runaway Events

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 ( 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 systems (ADS) have become an industry standard for hydrocracking units. However, the choice of other emergency actions taken before or concurrently with depressuring seems to be based on personal experiences and is not consistently applied in the industry.

Autodepressuring Alternatives

A quantitative method to rate the effectiveness of other safety actions to prevent a reactor runaway event or actions to be used concurrently with automatic depressuring in hydrocracking units is reviewed. The method is also suitable for rating and selecting appropriate emergency actions to stop a temperature excursion in hydrotreating units.

Appropriate emergency actions taken quickly enough may mitigate the need for a full reactor depressuring. While autodepressuring is an important safety device that must be available and utilised when necessary, it may be possible that the right emergency actions, taken early enough in a reactor temperature excursion event, could negate the need to initiate autodepressuring. In many refineries, flaring has come under intense scrutiny from regulators and communities, so avoiding or reducing flaring events has great value.

To read the full article, follow PTQ Q3 2023 Issue (

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About The Author

Jeff Johns has over 35 years’ experience in the petroleum refining industry. He was honored as a Chevron Hydroprocessing Fellow (Chevron’s highest technical recognition) for contributions to Chevron and to the industry. Jeff has expert knowledge of hydrocracker and hydrotreater design/operation, optimization, and troubleshooting, and has substantial experience in other key refinery processes. Jeff managed hydrocracking and hydrotreating technology in Chevron’s refineries worldwide where he developed and implemented best practices and projects to improve safety, reliability, and profitability. One of his special interests as a technology mentor was developing and delivering training. For 20 years, Jeff led an ad hoc Industry Committee of hydroprocessing experts dedicated to sharing safety and reliability information among North American Refiners. He was a member of the AFPM Q&A Panel in 2004 and directed multiple technology seminars as a member of the AFPM Q&A screening committee. Jeff served on the Board of Directors for Advanced Refining Technologies (ART). Jeff holds a B.S. degree in Chemical Engineering from the University of Utah. He holds six patents in hydroprocessing technology.

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Proactively Preventing Reactor Runaway Events

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