The Hybrid Process (patented) combines the best of the rerefining and cracking processes and has few of their drawbacks. It has 3 main processes:
- Like basic rerefining the Hybrid Process distills the feedstock so as to recuperate the base oils. However, the Hybrid Process is much less prone to fouling than present systems (fractionators, thin film evaporators) and can separate a wide range of products. This eliminates the need to make selective collections of oils, perform extensive testing on the arriving feedstock or pre-treat the oils.
- The oils that are left after the distillation are cracked in a rotating kiln containing plates, upon which the oil is sprayed. The plates serve as reaction sites and they protect the reactor walls from coke deposits, hot spots, and failure. As the kiln rotates, shelves lift the plates, keeping them against the reactor wall. When the plates pass the 90° point, they flip (presenting their hot side to the spray) and slide down, scraping the coke off the plates below. The kiln is a “dry reactor”, meaning that there is no liquid phase present. Each oil droplet takes the heat it needs to crack and vaporize from the plates where coke can deposit without affecting heat transfer. The reactor residence time is only a few minutes, whereas in other systems it goes from a few hours to 10+ hours. In the reactor, the metals and sulphur released by the cracking of additives combine with the coke to make an inert, non-leachable powder. The powder is easily separated from the fuel vapors as they exit the reactor, before the oil products are condensed.
- Like fuels produced in other cracking processes, the diesel fuel obtained is unstable. This means that, over time, it will produce gums and polymers and its color will turn from light yellow to dark brown. In refineries, unstable oil is hydrotreated to stabilize and desulphurize it, which is expensive, especially in capital costs. The Hybrid Process uses a recycled impure solvent extraction process that operates at ambient temperature and pressure. It is a relatively inexpensive extraction process as the solvent doesn’t need complete regeneration and can have a small amount of residual sulphur and other impurities.