NExCC™ -Novel short contact time catalytic cracking technology

ABSTRACT The demand for reformulated gasoline requires extending the flexibility of cracking operations to maximise the yield of light olefins and aromatics, both of which are to be used as building blocks for petrochemicals. Olefins are widely used for producing alkylates and oxygenates for the gasoline pool while aromatics are suitable for producing a large number of organic intermediates and chemicals. Fluid catalytic cracking combined with various hydrorefining technologies will be the main means used to meet the coming challenges for the refining industry. Demand for a short and exact contact time, higher temperature and a high catalyst/oil ratio, to produce more light olefins, has led to a new NExCC™ process incorporating a totally new reactor type. The NExCC™ design makes it possible to construct large equipment with a small height-to-diameter ratio. Compared to the conventional FCC, the NExCC™ product spectrum is much more olefinic. The process produces a higher conversion and less heavy components (> 221 °C). In a suitable setting NExCC™ can also serve as a source of increased propylene production. The gas velocity in a NExCC™ reactor is lower than in a FCCU riser. The flow type in the regenerator is totally different compared with that of the FCC and the reaction time is shorter. The NExCC™ process utilises multi-entry cyclones for separating catalyst from gas flows both in the reactor and the regenerator. The separation efficiency of the multi-entry cyclone is usually better than that of a conventional cyclone, and it is optimal for handling gas flows with high particle concentrations, such as in the NExCC™ process. Fortum Oyj has been developing multi-entry cyclone technology by using cold and hot model tests with different testing units and by using computational fluid dynamics (CFD) for analysis test results and for detailed cyclone design. For a scale-up of the process, models which predict with reasonable accuracy the flow field and chemical reactions both in the risers and the cyclones are required. In order to study the effect of the reactor operation conditions on the product yields and the product quality a kinetic model has been developed. The model takes into account the gasoline PONA-composition and includes eight product lumps with eight cracking reactions. A micro scale pulse reactor has been developed to obtain the parameters for the kinetic model.