The Dechlorination of Used Oil Products

Abstract

ABSTRACT

More than 1.3 billion gallons of used lubricants are generated in the United States annually, but only about 67 million gallons reach recyclers to be re-refined into clean lubricants. The rest is burned as a fuel or disposed of. Annually, almost 500 million gallons of used lubricating oil are injected directly into the environment through landfills or disposed of by other methods.

Because there is always a need to produce cleaner, higher quality oils from used oil recycling processes, the main objective of this study was to produce a low-chloride product from various used oil sources. The effect of processing conditions on the removal of chlorides from organic and inorganic components in the oil was also studied.

This study has shown that, by the innovative use of chemical and thermal treatment, a high-quality fuel oil can be obtained from a wide variety of used oil sources. Satisfactory dechlorination and ash removal from waste oil is optimized when each step influences a following step, leading to improved chloride removal. The chemical treatment destabilizes the chlorine compounds in the waste oil. Dechlorination is achieved only to the degree to which chlorides present in the waste oil are precipitated or converted to low-boiling-point compounds that can be distilled in a vapor phase. The chlorinated organic impurities are reduced to hydrogen chloride and other chlorides. Residual chloride content in the oil is derived from organic and other dissolved compounds that remain stable throughout treatment.

Treatment at temperatures in the range of 250°C destabilizes chloride compounds so that they split off hydrogen chloride at an increasing rate up to approximately 350°C. If the hydrogen chloride is not removed from the oil mixture, the reaction is partially reversible and dechlorination is only partially effective.

This new process offers greater flexibility for a broad range of feedstocks and optimal separation and removal of the chlorinated light ends.

The highly efficient removal of ash residues in the used oil should make this process attractive, where minimal waste production is an important regulatory and economic consideration. As more stringent air-quality regulations are imposed on industrial fuel oil burning, the need for low-ash, high-quality fuel oils from this process should offer economic advantages in the marketing of recycled used oil.