Solutions for the treatment of waste oils
Diesels obtained through a cracking process are unstable. With time, or when exposed to air, they produce gums and polymers, and turn from a light yellow to a dark brown color. In refineries, unstable oil is hydrotreated to stabilize and desulfurize it. This is expensive in both capital and operating costs. Used lubricating oils contain metals that can poison catalysts, and chlorides or nitrogen that increase hydrogen consumption.
Another method for stabilizing cracked oils is a liquid-liquid extraction process. This involves putting the oil in contact with a particular solvent to stabilize it, separating the two liquids to obtain a stable fuel and regenerating the solvent back to its original form. The problem with this method is that when using a pure solvent it has to be completely regenerated which is very expensive.
Sweet Gazoil™ has found a liquid-liquid extraction process to stabilize the oil that works best with a used solvent that has not been completely regenerated. Not only does it stabilize the oil, but it also reduces its sulphur content, dries it, improves its TAN (total acid number), reduces the sediments it contains and increases its cetane number. The details for this process can be found in the Canadian patent application number 2,694,821, which has already been deposited in many countries.