Deasphalted Oil Hydrocracker Helps Grupa Lotos In Poland To Enhance Its Economics
Gdañsk refinery is highly complex and the second largest refinery in Poland. But when increasingly stringent product specifications threatened its competitiveness, it took decisive action by launching the 10+ project, a massive $2 billion upgrade of the refinery.
The initiative, which was completed in 2011, has helped Grupa LOTOS to raise refining capacity by 75%, focus production on higher-margin diesel fuels, increase market share, and enhance margins by $5 per barrel.
Key to this scheme was a 45,000-barrels-a-day hydrocracker licensed by Shell Global Solutions that processes DAO. DAO is not a conventional hydrocracker feed; it has traditionally been used in refineries as a fluidised catalytic cracker feed owing to its high metals and Conradson carbon residue (CCR) contents. Vacuum gasoil (VGO) has a metals content of about 1–2 ppm and a 0.5%wt CCR content, whereas DAO typically contains 15–30 ppm metals and 6–10%wt CCR.
John Baric, Licensing Technology Manager, Shell Global Solutions, explains that recent advances in catalyst technology, which enable the catalyst system to remove the metals and manage other contaminants associated with DAO, have unlocked the potential of DAO hydrocracking. “The high metals and CCR contents are no longer problems; the state of the art has progressed and a well-designed catalyst system with demetallisation followed by pretreatment and cracking catalysts can handle DAO.”
The quality of the DAO is highly important, however. The DAO that feeds the Grupa LOTOS hydrocracker is prepared using an advanced solvent deasphalting (SDA) technology licensed by technology and engineering firm KBR, one of Shell Global Solutions’ alliance partners. Called the Residuum Oil Supercritical Extraction (ROSE) process, this provides superior-quality DAO that is suitable for hydrocracking because it has reduced levels of contaminants such as sulphur, nitrogen, metals and asphaltenes.
So how has the Grupa LOTOS hydrocracker performed over its first year of operations? “I am pleased to report that it is operating extremely well,” says Grzegorz Orzeszko, Deputy Manager, Hydrocracker Operations, Grupa LOTOS SA. “There have been no process upsets and, since start-up, all the performance guarantees have been met. There have been no product quality issues, and it is generating an extremely high yield of premium products.”
Dariusz Kruk, Manager, Hydrocracking Operations, Grupa LOTOS SA, says that the hydrocracker’s flexibility has been of special significance. The hydrocracker was designed to process a very heavy feed: 100% DAO derived from a ROSE unit processing a mixture of atmospheric and vacuum residue. But, owing to a reconfiguration, the refiner is using the unit to process a feed comprising about 50% DAO (from vacuum residue) and 50% VGO instead. At the same time, Grupa LOTOS took the opportunity to increase the conversion level from the planned 60% to 80–85%.
Kruk had anticipated that increasing the conversion beyond the design level would cause process issues, so his team worked closely with Shell Global Solutions and Criterion Catalysts & Technologies. “They help us throughout the run cycle,” he says. “They are fully aware of our technical strategy with the unit and what we are trying to achieve from the technical perspective. Before changing any process parameters, we always consult them and that approach is paying dividends.
One of the issues raised was a potential increase in polynuclear aromatics (PNA) levels, which could lead to heat exchanger fouling and catalyst deactivation. “Nothing is free, and this is the price of higher conversion and hydrowax recycling,” says Kruk.
“For stable hydrocracking operations, the PNA level must be kept within a certain window. So, with Shell Global Solutions, we analyse feed samples and create a PNA balance for the plant’s feed system. This has helped us to identify the most severe PNA streams, and now we preferentially route those away from the hydrocracker feed. Consequently, we have experienced stable hydrocracker performance.”
The catalysts have also demonstrated strong performance. “Even though the catalyst was selected on the basis of a different feedstock and for 60% conversion rather than 80–85% conversion, it is operating extremely well,” says Kruk. “The selectivity for middle distillates is very good.”
Grupa LOTOS routinely monitors the unit to make sure that increasing the conversion can be sustained for the duration of the planned cycle. Conventional hydrocracking parameters such as nitrogen remain important and the large quantities of DAO in the feed mean that the metals content and the CCR level must be carefully watched.
Grupa LOTOS has become the first refiner in the world to make this new generation of DAO hydrocracking technology operational, although more units have been designed, and Baric asserts that it will become an increasingly important technology. “Of KBR’s 50-plus references for operational ROSE units, only two feed a hydrocracker, but there is a clear trend towards this technology becoming more prominent. Indeed, Shell Global Solutions has designed four DAO hydrocracker units in recent years,” he adds.
One reason for this, he says, is market needs; hydrocracking is increasing in prominence at the expense of fluidised catalytic cracking as global demand for distillates rises and that for gasoline and naphtha diminishes. Another reason is economics and flexibility. “The combination of SDA and DAO hydrocracking is one of the lowest-capital-cost options for residue conversion directly to high-quality middle distillates, especially compared with other direct residue hydrocracking options, including the combination of delayed coking and hydrocracking.
“In addition, the unconverted residue from the DAO hydrocracker is a good feedstock for fluidised catalytic cracking units or for a base oil plant with the potential for producing heavy, high-viscosity base oil products,” Baric concludes.
For more details on Shell Global Solutions’ hydrocracking technologies
For more information contact John Baric