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Catalyst sulphiding with DMDS and Carelflex® service

Hydrotreating (HDT) catalysts must be con­verted to their sulphide forms to get the desired activity. This is traditionally car­ried out during unit start-up by injecting a sulphiding agent into the feedstock called dimethyl disulphide (DMDS). DMDS has 68 wt% sulphur and is efficiently converted to hydrogen sulphide (H₂S) on the hydrotreat­ing catalyst under standard sulphiding con­ditions. H₂S reacts immediately with HDT catalysts that become increasingly active until all active metals are fully sulphided. Over the years, DMDS has shown superior performance and has become the industry standard solution.
 
For the last 30 years, Arkema has sup­ported the development of DMDS refinery applications by offering a service to safely handle and carefully inject the DMDS, fol­lowing the procedure of the hydrotreating catalyst manufacturer. A major improve­ment has also been achieved with the use of in-line H₂S analysers (see previous arti­cles in ERTC newspapers in 2017 & 2018) that address a safety concern on the use of a reactive tube that would otherwise create a potential for exposure to H₂S for workers. Moreover, Arkema’s H₂S analys­ers offer a continuous H₂S measurement that allows the refinery to anticipate the DMDS flow rate and reactor tempera­ture changes, saving time and significant DMDS volumes.

Why offering a digital Carelflex®service?

Previously, sulphiding data (H₂S concentration, DMDS flow rate and cumulated amount injected) were shared by the Carelflex® operator with the refinery regularly and on demand. However, thanks to the latest advances in data management and communication, it is possible to collect all these data, for­mat them, and make them available to the refinery on a real-time basis (see Figure 1). This advanced service was introduced in Europe two years ago (See 2020 ERTC newspaper) and has grown quickly. Within less than two years, 50% of European refineries have shifted to real-time data transmission and communication using Carelflex® Connect, improving their sulphid­ing time by up to 20%.
 

A full digital project to meet refinery expectations

Figure 2 Instant messaging service and BOT enable the sharing of data and instructions
While real-time access to key data of DMDS catalyst sulphiding has been a great success, Arkema rapidly understood that the catalyst sulphiding and unit startup would benefit from a more advanced communication tool between the experi­enced on-site Carelflex team and the refin­ery production team.

As a result, in 2021 Arkema launched a secured and temporary instant messaging service (see Figure 2) for each operation that includes:
 
  • Secured access: a list of users is agreed with the refinery one week before and can­celled two weeks after completion of the operation. Catalyst supplier representa­tives may be given the same access when requested by the refinery.
  • Artificial Intelligence (BOT): The BOT uses the Chat function to send the latest value of DMDS and H₂S concentration data on demand. The refinery team use the BOT to send instructions to the Carelflex team, who acknowledge receipt from their tab­lets on site. Moreover, any DMDS flow rate change is automatically reported to the refinery team on the Chat by the BOT.
  • User-friendly platform: the instant mes­saging service provider Citadel™ is avail­able through a web page or mobile phone app and can be checked at anytime. Any member of the user group can check the entire Chat at anytime: it enables, for exam­ple, any refinery team member to track and understand the history of DMDS flow rate changes and related instructions upon the start of their shift.

Arkema’s H₂S analyser and digital plat­form greatly improved the efficiency of hydroprocessing units’ start-up sulphiding operations. These elements streamlined the process engineer’s focus and resources on critical unit parameter adjustments. Looking forward to these proven value-adds for future sulphiding operations.

These positive comments and the suc­cess of the advanced digital service have prompted Arkema to pursue investments in additional digital features that will ease the information exchange to prepare the on-site service, collect refinery feed­back, and promptly issue the final mis­sion report. At the same time, in 2022 Carelflex® Connect has been introduced in other parts of the world, such as the Middle East, North America, and Asia, where refiners welcome the application and adopt it rapidly.

Dimethyl Disulfide Applications

See also

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