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Arkema achieved its 6000th sulphiding job in September 2019 (ERTC)

Launched in the 1990s, Arkema’s injection service of dimethyl disulphide (DMDS) for the in-situ activation of hydroprocessing catalysts reached its 6000th operation in September 2019.

Francis Humblot
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Article Summary
This is the result of several stages of development overcoming different challenges thanks to innovative solutions implemented by Arkema.

The pioneer time…
In the early days, the service committed first to ensuring the safe handling of a dangerous and smelly chemical (DMDS) so that the refinery could enjoy all the benefits of an ideal sulphiding agent, combining a very high sulphur content (68 wt%) with a low decomposition temperature to maximise catalyst performance. To achieve this target, top quality equipment and connections were used by Arkema employees familiar with sulphur chemicals manufacturing processes, handling and standard prevention measures to provide a worry-free and zero-odour operation. In addition, this service had to handle many schedule changes due to unexpected events during turnaround just before the catalyst sulphiding operation and production start-up. The name of the service – Carelflex® – comes from the flexible Arkema organisation and high stewardship standards.

From 2000 to 2008, time for growth in developed countries
In areas such as Europe and North America, ever more severe specifications for transportation fuels came into force, reaching in 2006–2008 the very low limit of 10-15 ppm of sulphur in gasoline and diesel. This period saw major changes in hydroprocessing units and catalysts: new generation catalysts were launched every two years, and within less than 10 years hydroprocessing catalyst activity increased sharply. However, this activity increase was not enough and, in parallel, refiners had to increase significantly the size of their hydroprocessing reactors, especially for the diesel stream, to meet the new sulphur specifications. Arkema debottlenecked its DMDS production to supply the increasing demand and, to address HSE concerns, a more pure DMDS was marketed as a standard product. Moreover, Arkema introduced a new DMDS grade called DMDS Evolution®, in which a proprietary perfume was added to the standard product to improve odour and mitigate environmental inconveniences in case of incident. DMDS Evolution is now the market standard for spot uses such as the activation of hydroprocessing catalysts in refineries.

Arkema also reinforced its service offer with a more systematic use of pumps to reach higher injection flow rates, which allowed for the same sulphiding time despite the need for double quantities of DMDS for a revamped ultra low sulphur diesel unit.

2009-2018, a global demand   
Clean fuels regulations and more stringent sulphur specifications were slowly implemented in the rest of world. This trend is still not complete today, but major changes have occurred in the Middle East, South East Asia, and South Korea. Thanks to its know-how, Arkema anticipated these changes and extended its Carelflex service: new regional Arkema teams were implemented with reliable and standardised injection equipment so that the same high standard of service was available worldwide.

Meanwhile, in keeping with its policy of innovation, Arkema introduced an additional service for continuous measurement of H2S concentration in recycle hydrogen. The H2S analyser is delivered to refineries alongside the Carelflex equipment and is temporarily connected to the recycle hydrogen loop. After a few years of commercialisation in Europe and North America, this new service has proved to be a great success. It offers a safer operation than manual reactive tubes for measuring real-time H2S concentrations, and helps to anticipate DMDS flow rate changes, as well as optimise the sulphiding procedure, saving time and some significant DMDS volume (see previous articles in ERTC newspapers in 2017 and 2018).

More recently, Arkema has also developed a hydrogen purity analyser to work alongside its H2S analyser. Indeed, hydrogen purity must be monitored during catalyst sulphiding with DMDS to keep it above 60% purity, according to catalyst vendors’ guidelines. Arkema’s integrated equipment avoids the need to take manual gas samples, increasing safety. It also gives a real-time indication that eases hydrogen make-up and flaring management.

Next challenges and major changes
Safety, reliability and flexibility are the core values of Arkema’s Carelflex service. The 6000th sulphiding operation achieved recently highlights the market recognition of these values.

In the future, Arkema foresees that digital technologies will offer easier communication during sulphiding and further monitoring to provide better anticipation and  also improve safety in the sulphiding environment.

This short article originally appeared in the 2019 ERTC Newspaper, produced by PTQ / DigitalRefining.

You can view the digital issue here -
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