Process and system for recovering base oil from lubrication oil that contains contaminants therein

Abstract

A process of recovering base oil from lubrication oil that contains contaminants therein, the process comprises the steps of: (i) extracting a light diesel fraction from the lubrication oil; and (ii) distilling the lubricating oil under vacuum conditions after said extracting step (i) to obtain a base oil that is substantially free of said contaminants.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to the disposal of spent lubrication oil, and more particularly to processes and systems for regeneration of spent lubrication oil into multiple fractions including base oil by employing rectification and multi-stage molecular distillations.BACKGROUND OF THE INVENTION[0002]The refinery process of crude oil produces a fraction of oil that is suitable for lubricating purposes, called base oil. In practice, the base oil is obtained and separated into fractions in the vacuum distillation column which is fed by the residue of an atmospheric column. Generally, only about 3-5% of the crude oil is suitable for being used as base oil. Due to various viscosity requirements for different lubricating purposes, the base oil must not be either too volatile or too viscous.[0003]As its term suggests, the base oil is used as the base for formulating lubrication oil. To improve the quality of the lubrication oil are added multiple ad...

AI Technical Summary

Benefits of technology

[0016]In one embodiment, there is provided a process for treatment of spent lubrication oil. The process may comprise the steps of pretreating the spent lubrication oil, rectifying the pre-treated spent lubrication oil to recover a light diesel fraction from the spent lubrication oil to reduce or eliminate interference in subsequent molecular distillation caused by the light diesel fraction, and performing multi-stage molecular distillations of the rectified spent lubrication oil to recover multi-grades of base oil, such that the recovered light diesel fraction and base oils obtained can be used for further applications, and the remaining of the spent lubrication oil can be discharged.

[0022]Another embodiment of the present invention provides a system for regeneration of spent lubrication oil. The system comprises a pretreatment unit for pretreating the spent lubrication oil, a rectification unit fluidly coupled with the pretreatment unit, for rectifying the pre-treated spent lubrication oil to recover a light diesel fraction from the spent lubrication oil to reduce or eliminate interference in subsequent molecular distillation caused by the light diesel fraction, and a multi-stage molecular distillation unit fluidly coupled with the rectification unit, for performing multi-stage molecular distillations of the rectified spent lubrication oil to recover multi-grades of base oil, such that the recovered light diesel fraction and base oils obtained can be used for further applications, and the remaining of the spent lubrication oil can be discharged.

[0028]One advantage of the present disclosure is the production of multi-grade base oils from a single process with a multi-stage molecular distillation design. This maximizes the value of recycled product and provides greater flexibility in lubrication product manufacturing.

Problems solved by technology

When lubrication oil is used, it is being contaminated by extraneous contaminants introduced from the surrounding air and the engine.

Contaminants from the air include dust, dirt, and moisture; and air itself may be considered as a contaminant since it might cause foaming of the oil.

During lubrication oil usage many matters may be formed causing the deterioration of the lubrication oil.

The properties of lubrication oil are affected by any contaminants that may occur during operation.

For example, water, even in small amounts causes rusting of iron or steel.

Water also results in the forming of water sludge (emulsions) which may clog oil passages, pump valves and other oil handling equipment, may contribute to foaming problems, and may lower the electricity insulation property of lubrication oil.

Furthermore, solid particles such as dirt, dust, grit and metallic fragments cause excessive wear, scoring of bearing surface, and possible failure due to seizing of metal fatigue.

In addition, sludge deposits may clog small oil passages and clearances; lacquers or varnish cause the sticking of valves, and may adversely affect the continuous operation of oil pump.

Finally, liquid contaminants such as unburned fuel from engines may dilute the lubrication oil which may then reduce their viscosity beyond a safe load.

Contamination of the lubrication oil with heavier oil may increase its viscosity and may interfere with the oil circulation, affecting the lubricating valve and heat transfer capacity.

Problems arising from acid treatment include environmental issues associated with the disposal of acid sludge and spent earth, low product yield (45-65%) and incomplete removal of metals, especially lead.

For conventional distillation, the main problems encountered are plugging of the lines, fractionators and furnace tubes due to formation of a resinous material that fouls the equipment, cracking of molecular due to high distillation temperature and polymerization to form solid substance.

Conventional distillation processes do not improve the dark color of the products obtained.

Solvent extraction processes have the problems of high operating cost, complexity of the process and generation of secondary waste, e.g. waste solvent and waste water.

Ultrafiltration is still in experimental stage and the main problem encountered is the fouling of membranes and incapability to manage the flash point of the products.

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