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Revamping a hydrotreating unit for improved hydrogenation of diesel
Preem AB has implemented the “gasoil project”, a major investment program to optimise conversion for middle distillate production at the refinery in Lysekil.
Revamping a hydrotreating unit for improved hydrogenation of diesel
After the start-up of this project, Preem AB recognised the need to reach a new level of operational excellence in order to maximise their return on investment. Shell Global Solutions was appointed to perform a Hydrocarbon Margin Improvement Program (HMIP), working closely with Preemraff Lysekil to identify, develop and deliver margin improving initiatives across the refinery.
One of the margin improving opportunities identified by the HMIP was to increase the production of Swedish MK-1 diesel from the 2-Stage Middle Distillate hydrogenation unit operating at Preemraff Lysekil.
Working closely with the Preemraff Lysekil technologists, the catalyst and reactor internals team from Shell Global Solutions and Criterion Catalysts & Technologies identified that the unit throughput could be increased by implementing a catalyst & reactor internals revamp on the 1st-stage pre-treat reactor (R1) of this unit.
The expected increase unit throughout was 20 Sm3/h. With a refinery turnaround scheduled to happen within 7 months of identifying the opportunity, the project justification, design and confirmation (through pilot plant testing), of this solution had to be completed quickly and the project fast-tracked for speedy implementation.
The initial economic justification for the revamp project was based on recovering the cost of the reactor internals (a one-off cost Capital expenditure) and the on-going cost of extra catalyst, within the first 5-6 months of operation.
Record production of Swedish Mk-1 diesel was reported soon after the unit started-up and the unit continues to perform at the level expected when the project objectives were set, with average throughput remaining 40 Sm3/hr higher than in the previous run.
In the event, weaker than expected margins meant the break-even point on the project was pushed back by 3 months and the investment was recovered in the first 8-9 months of operation. After 20 months of an estimated 5 year cycle, Preem AB estimate the contribution will be close to 1.7 Million US$/annum on-going.