Surviving the global economic and legislative tsunamis
Changes and challenges are sweeping the refining industry into a new era. Primary processing units will remain essential, but their roles will change drastically
Patrick J Christensen, Thomas B Garrett, Brett P Goldhammer, Erich J Mace and Thomas W Yeung
Hydrocarbon Publishing Company
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For refiners, changes and challenges are constant, from the record-high crude prices of mid-2008 to the marked demand collapse seen since late 2008. Analysts believe that the global economic recession and credit crunch, which are largely responsible for the drop-off in fuel consumption, could continue into 2009–2010. Once the world recovers from the economic downturn, the demand for oil and refined products will increase, although refiners will be confronting a relatively new environment.
A fundamental question is, “Will a refiner still be in business in the next ten years?” The next decade represents a watershed era that will bring about a drastic shift in the refining industry. The current fuel consumption collapse may be just a temporary threat in comparison to the uncertainties and potential earnings-damaging environmental mandates and market erosion of the future. Refiners must act now by reconfiguring their plant operations, especially the three workhorses — FCC, hydrotreating and hydrocracking — in order to remain profitable. In particular, high-impact revamp areas are those that address ultra-clean fuels supply, product demand shift, use of heavy crudes and renewable feedstocks, and CO2 emissions reduction, as illustrated in Table 1. To provide an underlying basis for sustainable refinery operations, these revamps should also include â€¨ways to increase productivity and improve energy efficiency.
Current state-of-the-art technologies and the latest research works that show promise in bringing forth the changes required to ensure refiner profitability and legislative compliance are highlighted. The following R&D discussions are based on reported research literature and extensive patent analysis.
Fluid catalytic cracking
The FCCU continues to perform “miracles” for refiners in light of increasingly stringent fuel standards, changing market conditions and competing technologies. Its role has expanded from a gasoline-producing machine to an olefins maker, sulphur remover, residue upgrader and possibly a significant contributor to the ultra-low-sulphur diesel (ULSD) pool. These FCC technology advances are drivers of the perpetual refinery profit cycle. Over the next two decades, the FCCU may take on two additional roles — biofeeds user and refinery CO2 emissions reducer — to alleviate growing concerns over energy security and global warming. With committed efforts by refiners and technology developers, the FCC process will continue to demonstrate superior adaptability amid changing market requirements and offer refiners novel ways to make money.
Boosting diesel make
Diesel is a fast-growing transportation fuel in terms of demand. A recent study by consultancy Booz & Co reported that dieselisation is a worldwide phenomenon, and that the gasoline-to-diesel demand ratio will shift from â€¨50:50 in 2007 to 45:55 in 2030.1 The consultancy also expects regional imbalances in fuel supply to be magnified over the next several years as a result of the growing global shift. It would therefore be advantageous for refiners to achieve a level of flexibility in the FCCU, producing varying amounts of gasoline and light cycle oil (LCO) as the market changes. The FCCU contributes about 30% of the LCO supply in the US, but this percentage is much higher in Europe, Asia and Latin America, where middle distillates are in higher demand. Furthermore, Europe, China and Brazil are known to be short of diesel.
FCCU LCO production can be increased by modifying feedstock composition, introducing improved catalysts and additives, and modifying operating conditions, such as the recycle ratio, temperature and catalyst-to-oil ratio. The addition of an active alumina matrix is a common feature to help refiners increase LCO production when cracking heavy feeds. According to a recent patent survey, the use of an inorganic additive such as P2O5 in â€¨catalyst formulations is cited, as are metal-doped anionic clays and amorphous silicoaluminophosphates (SAPO). Some overlap exists in catalysts tailored for LCO production and those tailored for resid feeds. Consequently, refiners looking to produce more diesel may want to consider heavier feeds for their FCCU. Process/hardware technologies to improve FCCU LCO yield include proper feed injection systems and dual riser/reaction zone designs, as claimed by Petrobras, Shell and Sinopec in their latest commercial processes. Finally, the use of biofeeds in the FCCU to produce a large volume of high-quality LCO has also received attention. These feeds — namely, animal fats and vegetable oils — not only increase LCO yield, but also provide high-quality products in terms of cetane number.
Processing heavy crudes and â€¨residual oils
Refineries equipped to process heavy crudes have, to date, tended to achieve high refining margins in the long run because they take advantage of cheaper, heavier oils. Figure 1 shows the US West Texas Intermediate (WTI)-Mexican Maya heavy oil discount over the past ten years. As the price of light sweet crude WTI climbs, the discount gets wider. However, the discount shrinks when the WTI price declines.2
Resid fluid catalytic cracking (RFCC) is an important component in the upgrading of such crudes, with unit profitability depending upon the extent to which heavy hydrocarbons in the â€¨feed are cracked into valuable products. The product slate, in turn, depends â€¨upon feed characteristics, catalyst, hardware and operating conditions. Exemplifying a trend toward heavier feeds, 70% of the new FCCUs scheduled to start up between 2006 and 2015 are expected to process heavy vacuum gas oil (HVGO) or resid feeds.
Feed characterisation is an important first area of improvement. Although it is likely the lowest impact option, predicting unit dynamics caused by feed changes is important in optimising unit operation, especially for high-impact feeds like resids. Complete RFCC process technologies are the most comprehensive approach to improving resid processing operations, but the offerings are also the most expensive. Product recycle and multiple reaction sections seem to be the most prevalent technology trends. Improving feed injectors, riser termination and catalyst separation devices, strippers and regenerator components are good revamp options for existing units. As feeds get heavier, the trend toward a higher stripper residence time and, consequently, increased mass transfer between entrained hydrocarbons and steam will continue. Moreover, the role of the regenerator continues to evolve because of CO2 reduction requirements.
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