Oct-2002

Improvements to increase fuel capacity and quality

By using staged technology upgrades, fuels production at the Jiddah refinery was expanded and quality improved, meeting market and regulatory criteria

Christopher F Dean, Saudi Aramco
Jay L Ross, Axens North America

Article Summary

The fluid catalytic cracking unit (FCCU) at the Saudi Aramco Jiddah refinery has played a pivotal role in refinery-wide improvements and planning necessitated by shifting transportation fuels demand and specifications. Improvements to the refinery’s FCCU and downstream product upgrading requirements, are an example of what is needed to meet these new demands and specifications in a cost-effective manner. Fuels production was expanded while also meeting new clean fuel specifications in spite of severe capital constraints.

Two primary objectives were improving FCCU conversion to reduce fuel oil byproduct and optimise refining product margins while achieving regulatory compliance.

Refiners must make complex decisions involving large expenditures in a world of economic and regulatory uncertainty. To help offset this uncertainty, most refiners are trying to do more with less – but with an eye to expansion and compatibility with future demand and legislation, while seeking synergy and integration of business decisions. In many cases, an uncertain future compels planners to pursue lower capital cost, incremental improvement or revamp investments, instead of higher return but more costly step-wise strategic investments.

The Western Region refinery in Jiddah is a small 60000bpd facility supplying motor fuels, lubes, and fuel oil. The refinery’s FCCU is a 1974 UOP side-by-side unit with a hot wall reactor design. The unit has undergone several modifications in the past 10 years. The complex, like all Saudi Aramco facilities, is subject to constant review and evaluation for continual improvement, and is considered to be a key strategic capital asset.

Some of the recent modifications to expand the capacity and conversion potential have been described [Anderson S V, Improved FCCU feed catalyst contacting; PetroTech 1998 Middle East Refining and Petrochemicals Exhibition and Conference].

The capacity has been expanded from 13000 to 20000bpd and yield selectivity improved with the addition of Axens/Stone & Webster elevated radial feed injection, resulting in an overall $10.8 million/year increase in revenue.

Refinery profile
Saudi Aramco is a large, integrated, international oil company with interests in 11 refineries processing 3.4 million bpd crude oil worldwide. In the Middle Eastern/Asian marketplace the company has interests in nine refineries ranging from low conversion complexes such as Rabigh in Saudi Arabia, to state-of-the-art full-resid conversion facilities such as the S-Oil complex in Korea.

In the global markets in which Saudi Aramco participates, gasoline production for domestic use or export is still strong despite the overall growth of diesel consumption. Against this trend is reduced worldwide fuel oil demand. Ahead of these projections is the regulatory trend for cleaner fuels resulting in very sharp reductions in product sulphur (Table 1).

For Saudi Aramco these industry dynamics including increased transportation fuels demand, reduced fuel oil demand and tighter product specifications, are particularly challenging due to the relatively high sulphur level of Arabian crudes and the mature nature of domestic refining facilities. The appropriate response to challenging industry changes and captive growth markets will largely depend on the refinery location and existing assets already in place. In general, the lowest cost conversion unit to produce transportation fuels and reduce fuel oil production is the FCCU. When this unit is present in an existing facility, as is generally the case, full FCCU utilisation is the most profitable option. It requires increasing attention to product and effluent treatment to meet ever-tightening regulations creating more income pressure.

As an alternative, severe FCCU feed hydrotreating/hydrocracking of both distillate and resid feeds can fully address the fuels balance issues and product quality requirements as demonstrated by the state-of-the-art configuration shown in Figure 1.

This comprehensive option is perhaps better suited for newer complexes where engineering adaptation to meet regulatory and market trends can be more readily implemented and economically attractive, as opposed to remediation of older early-generation facilities that have evolved with incremental solutions to evolving market and regulatory change.

Blending challenges
The Gulf Cooperation Council (GCC) countries moved to 100% unleaded gasoline in 2002 and Saudi Arabia had already introduced unleaded gasoline in January 2001. Saudi Aramco has unique gasoline blending challenges to meet Saudi Arabian gasoline specifications due to the lead phase-out and reductions in sulphur and other components. This is particularly the case in the Western Region where FCCU naphtha (gasoline) is a larger blending component in finished gasoline.