40 years ago the whole game changed. Simply put, there are two different eras in the specialist world of refinery hydroprocessing. Before 1979 and after.
So much has changed since that fork-in-the-road year that many of the current (and future) generations of engineers probably aren’t aware of how much Topsoe’s introduction of active grading technology altered the path of the entire industry. Until 1979, the bulk catalysts that refineries were using in their hydroprocessing operations didn’t get much of a chance to do their job effectively. The feedstocks they were using featured high levels of contamination and all kinds of other undesirable gunk. Unscheduled pressure drop was a constant problem, and it happened all too often.
Problem prevention more than results and output
Back then, the only effective way for refineries to deal with this serious problem was by installing space-hogging combinations of filters, trash baskets and inert ceramic balls. The aim was to keep contaminants out of the bulk catalyst bed below. Unfortunately, this all took up space in the reactor and disrupted the distribution of both gas and liquid, without providing any catalytic activity or efficiency payoffs. Furthermore, this was basically a ‘trial and error’ era of refinery hydroprocessing operations, with only limited mainstream understanding about the atomic level chemistry underpinning what was happening in the reactor. And it wasn’t going well. You can read about the situation back then in an old article – Raschig ring HDS catalysts reduce pressure drop - from the 1984 edition of Oil&Gas Journal.
From balls to rings – space management
All this changed in 1979, when Topsoe introduced a world-first grading capability for hydroprocessing reactors, based on catalyst material extruded into active tubular rings. These were for use above the bulk catalyst.
The large hole through the centre of each pellet means there is a considerable surface area – both inside and outside – where liquid and gas vapors are able to interact with the catalyst material, to bring the catalyst’s capabilities into play effectively.
Read the article online at: https://www.worldfertilizer.com/materials-handling/08032019/life-before-grading/