HydroDeSulphuriser (under)performance investigation
ULSD operation environment
In today’s 10 ppm Ultra-Low Sulphur Diesel world, the HydroTreater (HT) or HydroDeSulphurisation (HDS) unit has become an upgrader with an appreciable contribution to the Refinery Margin. Some of them were recently built, some of them are decades old and have been revamped to the new specifications, but the incentive to improve on their bottom line will not disappear. Underperformance is costly and effective troubleshooting is required to quickly recover the lost margin in a sustainable manner.
Unit health check - optimal catalyst performance
3.Catalyst cycle & feedstock optimisation
Findings can also be input for longer term optimisation, such as the next cycle catalyst selection and/or future revamp options.
1.Review of unit planned and un-planned down-time can bring up options to improve unit availability.
2.Review of the unit energy use by checking the heat-exchanger duties, furnace efficiency and steam use.
3.Yield check: this can be improved if the separation of slops in the work-up section is poor. For example, reducing give-away on Flash Point is a way to boost product yield.
4.For the unit integrity its water balance needs to be reviewed to ensure that the ammonium salts that are produced in the reactor are continuously being removed.
Secondly, a check of the loading diagram is required to assess maximum catalyst activity as well as its resistance against fouling.
Upgrading conventional trays with State-of-the-Art ones can easily add 20% catalyst activity. This activity increase can then be used to extend catalyst life or increase feed rate/heaviness, assuming extra H2 is available.
Catalyst cycle & feedstock optimisation
An HDS Health Check will allow for fine-tuning of equipment in daily operation as well as for extracting maximum benefit from the catalyst load.