Chemical Engineering Partners offers a complete process for treating used oil to produce base oil, which meets API Group II specifications. In some situations, our clients do not require all components of our process technology. CEP is happy to work with you to meet your specific needs. On past projects we have done the following:
There are also other alternative processes available on the market in lieu of hydrotreating. These processes include:
In the acid clay process, used oil is typically filtered and then heated to remove debris, solid particles and water. It is then mixed with sulfuric acid which extracts metal salts, acids, aromatics, asphaltenes and other impurities. This forms a by-product of acidic sludge that settles out of the oil. The remaining slightly acidic oil is mixed with active fuller’s earth (clay) to remove mercaptans and other contaminants and to improve color. This process requires approximately 0.4 lb of clay per gallon of oil. After clay is filtered from the oil, the final steps are neutralization and distillation of the oil. Acid clay treatment was the predominant technology in the past. According to the US DOE study, there were 150 re-refiners using Acid/Clay in 1960 processing 300 million gallons per year. In 1976, it dropped to 25 active re-refiners processing 51 million gallons per year. Today, in many countries and states, the acid clay process is illegal due to the hazardous waste of the acidic clay from the process.
Vacuum distillation is a simplified “Front End” of the CEP process. It takes advantage of the use of boiling point properties of the used oil to separate various components; water, light hydrocarbons and gas oil, lube distillate and asphalt flux. Vacuum is used to prevent thermal cracking of the hydrocarbons. The main product of vacuum distillation is the lube distillate. While lube distillate technically meets the definition of API Group I base oil, it is not suitable for motor oil. The typical uses for lube distillate are bar and chain lube, process oil, form oil or fuel. Clay treatment can be used to improve the appearance of the lube distillate.
Clay treatment is often used as a finishing step for lube distillate from vacuum distillation. There are two methods of clay treatment. The first is static beds where lube distillate is fed through the static beds of clay at elevated temperatures. The second is contact reactors where lube distillate is mixed with clay and kept in suspension and then filtered to remove the clay. For the clay to effectively treat the oil, it needs to be activated by heating. The clays can be regenerated through a controlled combustion cycle and can be used multiple times before being disposed of. The clay treatment removes color, odor and some sulfur. The finished product meets API Group I base oil specifications but does not remove the unsaturated compounds to meet API Group II specifications. Clay treatment may be better suited for smaller plant capacities due to lower capital investment.
Solvent extraction is used to improve the quality of lube distillate that is produced from a vacuum distillation process. The solvent is used to extract polar compounds, additives and color bodies. It removes aromatics and increases saturates level. One drawback to solvent extraction is that it removes the unsaturated compounds, reducing the overall yield. This is in contrast to hydrotreating which converts these compounds. Solvent extraction produces API Group I base oil that meets motor oil specifications but does not meet API Group II specifications due to its inability to remove sulfur.
Contact Chemical Engineering Partners today to see how we can help you!