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Nov-2019

Rejuvenated catalyst cuts changeout costs (TIA)

Today refiners are faced with the daunting task of transforming an ever changing crude slate into a wide range of products.

Guillaume VINCENT
Porocel

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Article Summary

With a continuous emphasis on profitability under increasingly stringent environmental regulations, the most advantageous path is not always clear. Collaboration between Porocel and refiners enables them to maximise profitability and remain environmentally conscious with their hydroprocessing applications.

One such refiner is Varo Energy in Switzerland. Their goal was to upgrade a blend of LGO, VGO, and coker distillate to produce two different diesel products. Prior to choosing Porocel, Varo had the option of purchasing fresh catalyst which would have amounted to a higher fill cost, at equal cycle length and product quality. The refill was won by presenting technical projections that were in line with their performance objectives. Porocel installed a high activity Excel rejuvenated NiMo catalyst to help the refinery extend the hydroprocessing unit cycle until the next turnaround. Excel rejuvenation allows re-dispersing agglomerates on the regenerated material to restore its activity to near fresh by utilising a proprietary chemical treatment.

Varo Energy and Porocel worked together to meet an aggressive timeline for the catalyst changeout and ensure that unit product quality met all specifications. Porocel designed a catalyst load incorporating high activity Excel rejuvenated catalyst, CatGuard (top bed grading) and bed support (Durocel-222). The catalyst was proposed to maximise HDS/HDN activities and polyaromatics hydrogenation. Due to the presence of arsenic in the feed, Porocel supplied the fresh CatGuard As40 (high nickel content) to protect the main bed catalyst from arsenic poisoning.

The feed and operating conditions were carefully evaluated to optimise catalyst system design and simultaneously meet multiple unit objectives. Throughout the technical evaluation, there was a commitment to ensure high catalyst quality to maximise performance and reliability. Varo Energy operated the DHT unit in two modes:
1)    Ultra low sulphur diesel (ULSD) mode by processing a blend of light gasoil (75 wt%), heavy gasoil (3 wt%), vacuum gasoil (2 wt%), and cracked gasoil (20 wt%)
2)    Heating oil (ECO) mode by processing a blend of light gasoil (20 wt%), heavy gasoil (45 wt%), vacuum gasoil (15 wt%). and cracked gasoil (20 wt%).

As a result, the unit was able to process a blend of light and vacuum gasoil with coker distillate to produce two grades of final product. The unit achieved the projected cycle length while reducing catalyst expense. A summary of the feed and operating conditions is shown in Table 1.

The Excel rejuvenated NiMo catalyst selected from Porocel’s inventory provided high hydrodenitrogenation activity combined with deep desulphurisation levels to handle the high nitrogen concentration in the feed blends. The primary objectives of the hydrotreater were (see Figure 1):
-  To produce ULSD, targeting a product sulphur of 11 wtppm
-  To produce heating oil (ECO mode), targeting a product sulphur of 55 wtppm.

Excel rejuvenated catalyst gave Varo Energy the expected performance, while enabling substantial cost savings versus loading fresh catalyst. A breakdown of the fill cost savings is shown in Table 2.

This unit successfully produced on-specification product for both modes throughout the duration of the cycle with Excel NiMo on par with the previous cycle loaded with fresh alternative NiMo catalyst. The normalised weighed average bed temperature (WABT) for both cycles is shown in Figure 2.

The refining industry is continually focused on value. Refiners seeking high activity hydroprocessing catalyst while keeping a close eye on catalysts costs are very well served by this method of rejuvenation. It can be applied to catalyst from the refiner’s own units (as a service) or to regenerated catalyst from Porocel’s own catalyst inventory. By combining Excel rejuvenated catalysts with other HPC products, such as Durocel-222 (ceramic support) and CatGuard metal traps, Porocel’s HPC solutions enable refiners to achieve unit objectives while saving 30-70% over the cost of fresh catalyst loads. In addition, catalyst reuse helps refiners to significantly reduce the cost and the environmental impact of catalyst disposal. Porocel maintains a global inventory of rejuvenated catalyst for use in combination with fresh catalyst or on its own.

This short case study originally appeared in PTQ's Technology In Action feature - Q4 2019 issue.

For more information: gvincent@porocel.com


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