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Maximising diesel production through integrated hydroprocessing

Maximising diesel production through integrated hydroprocessing

John Baric – Licensing Technology Manager, Shell Global Solutions International B.V. and Justin Swain – Technical Director, Criterion Catalysts and Technologies Ltd discuss specific technology differentiators and case studies which resolve key unit performance issues and boost margin for refiners.

Hydroprocessing faces significant challenges as crude feeds get heavier; there will be more sulphur and nitrogen to extract; more aromatics to saturate; more metals to remove; and more coke to deal with. Refiners also have ageing facilities, which may not be designed and optimised to meet these new challenges.

In an economic environment of constrained capex, many refiners have successfully revamped their existing hydroprocessing units with Shell’s reactor internals technology and the latest generation of catalysts from Shell’s partner Criterion – the largest global supplier of hydroprocessing catalysts. In order to get maximum value from a revamped unit, the catalyst and the quality of the reactor internals must both be optimized.

The catalysts have to be protected from particulates and foulants, and the reaction and catalyst utilisation must be maximised. In any multi-bed hydrocracking reactor, for example, particulates can accumulate even if sophisticated automatic backwash feed filters are present, affecting top bed catalyst performance.

Optimum reactor internals design is vital. Shell installs filters into the top dome of all vacuum gas oil (VGO) hydrocrackers and residue hydrodesulphurisation (HDS) units, without effecting reactor size, cost or affecting active catalyst volume. The filters have proven to be extremely effective for coarse removal of particulates that could cause pressure drop and misdistribution in the catalyst bed. A liquid-vapour distribution tray beneath the filters ensures that vapour and liquid have full radial dispersion across the catalyst bed, resulting in nearly 100% utilisation of the catalyst.

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