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Improved process for recycling used motor oil produces higher-grade base oils

| By Scott Jenkins

Front-end engineering design (FEED) is underway for a facility designed to de-contaminate and upgrade used motor oil from passenger vehicles into a higher-value product mix of base oils than is currently possible with existing motor-oil recycling processes, and in a way that lowers capital and operating costs compared to current processes. The project is being undertaken by ReGen III Corp. (Vancouver, B.C.;, a technology developer focused on re-refining used motor oils, and is supported by engineering and modular construction firm Koch Modular Process Systems LLC (KMPS; Paramus, N.J.;, which developed extraction and distillation technologies used in the process.

Initially, collected used motor oil enters a contamination separation unit (CSU), where low- and high-boiling compounds are removed to achieve a desired boiling-point cut. “This step removes some impurities and color, and allows for variability in feeds because it refines any feedstock into a similar boiling point range,” explains Mark Redcliffe, executive vice president at ReGen III. The next stage involves a combination of liquid-liquid extraction and distillation. “The extraction step principally removes color bodies and improves certain physical properties, such as viscosity,” says Wendy Parker, vice president of process engineering and pilot testing at KMPS. The distillation focuses on removing and recovering the solvent from the extraction-product streams (extract and raffinate). From this step, a high-quality Group III base oil is produced (up to 65 vol.%) that does not require further processing.

“Competitive processes are not generating Group III base oils, a higher-value product than the Group I and II oils typically generated in used motor oil recycling,” says Redcliffe. Group II base oils are also produced (up to 25%) and continue to hydrotreating in the third stage. While alternative processes hydrotreat all incoming material, the ReGen III process requires hydrotreating for only about 30 vol.% of what comes from the CSU, explains Redcliffe, so the new process employs a smaller hydrotreating unit, resulting in lower capital costs. And since less consumable material is needed, operating costs are also lower, he adds.

Additionally, the ReGen III process utilizes liquid hydrogen, which allows for greater saturation of the lubricant molecules and results in a higher-grade Group II-plus base oil product, Redcliffe notes.

FEED for the project is scheduled to conclude in Q1 2022, and commissioning the finished re-refinery is currently planned for the second half of 2023, project leaders say.