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Life before grading

07.03.2019

Grading

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 center 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.

  % VOID (sock loaded)
Spheres (support balls) 33%
Cylinders 40%
Rings* 53%

* Rings with OD/ID ration of 2:1

But these shapes were new for the catalyst materials required in the hydroprocessing operations in refineries. Their extruded tubular shape provides what is known as random packing, and enabled feedstocks to flow through much more freely than with traditional inert solid spheres.

Accelerating excellence

Refineries worldwide were eager to take these new Topsoe grading solutions on board to boost the efficiency and reliability of their hydroprocessing operations.

The idea was first commercially applied in 1979, and proved a reliable success. The take-up rate accelerated in the 1990s and the 2000s, and it gradually became the accepted “gold standard” for refinery reactor operations because it so effectively prevents unscheduled pressure drop.

The scope of Topsoe catalyst grading products has also been growing fast, with new generations of this pivotal technology emerging at an increasing pace. We have sold a total of more than 6000 charges of our unique catalyst grading products to date, with more than 4000 charges delivered since the turn of the millennium.

More than 350 refinery customers worldwide now depend on our grading and catalyst products and services in their hydroprocessing operations.

How grading catalyst rings pay off

Ring-shaped grading catalysts provide multiple payoffs. These include:

  • Greater void
  • Better flow
  • Stepped increase in catalyst activity
  • Better control of pressure drop across the reactor
  • Greater run length

Haldor Topsoe pressure drop control process offering

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