Used Lubricating Oil Re-refining via Stripping and Extraction
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Solution Overview
Problem
Liquid-liquid extraction processes for re-refining used lubricating oils face economic inefficiencies due to high solvent volume requirements and low-quality oil production, leading to higher costs and equipment fouling, making them less attractive than hydro-finishing despite environmental benefits.
Innovation Solution
The process involves nitrogen stripping using a trayed column with multiple theoretical plates, followed by liquid-liquid extraction with a polar organic solvent like N-Methyl-2-Pyrrolidone, which efficiently separates contaminants and recycles solvents, reducing fouling and solvent usage, and producing high-quality re-refined base oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If liquid-liquid extraction is used for re-refining used lubricating oil, then hydrogen consumption is eliminated and environmental safety is improved, but solvent volume requirement increases and base oil quality decreases
Solution Approach 1:
The patent applies preliminary action by implementing a stripping column before the extraction unit. This pre-treatment step removes light ends and contaminants from the used lubricating oil, preparing it for more efficient extraction. The stripping process eliminates substances that would otherwise consume excessive solvent during extraction, thereby reducing the overall solvent volume requirement while maintaining environmental safety benefits.
Solution Approach 2:
The patent employs parameter changes by optimizing extraction conditions including temperature, pressure, and solvent-to-oil ratio. By carefully controlling these parameters and implementing multiple extraction stages, the process achieves effective contaminant removal with reduced solvent consumption. The parameter optimization ensures high-quality base oil production while minimizing the quantity of solvent required.
2Object-affected harmful factors
If liquid-liquid extraction is used for re-refining used lubricating oil, then hydrogen consumption is eliminated and environmental safety is improved, but base oil quality becomes relatively low
Solution Approach 1:
The patent applies segmentation by dividing the re-refining process into distinct stages: stripping, extraction, and finishing. Each stage targets specific contaminants and uses optimized conditions for that particular separation task. This segmented approach ensures that each unit operates at peak efficiency, collectively producing high-quality base oil while maintaining the environmental advantages of eliminating hydrogen consumption.
Solution Approach 2:
The patent implements continuity of useful action through a multi-stage extraction process where raffinate from one stage becomes feed for the next. This continuous action ensures progressive removal of contaminants without interrupting the flow, maintaining consistent base oil quality throughout the process while preserving the environmental benefits of the extraction method.
3Ease of manufacture
If liquid-liquid extraction is used for re-refining used lubricating oil, then catalyst replacement and handling are eliminated, but equipment fouling increases
Solution Approach 1:
The patent applies preliminary action by implementing a stripping column that removes contaminants prone to causing fouling before the extraction unit. This pre-treatment step eliminates substances that would otherwise accumulate on equipment surfaces during extraction, thereby reducing equipment fouling while maintaining the operational simplicity advantage of eliminating catalyst handling.
Solution Approach 2:
The patent employs extraction to specifically remove fouling-prone contaminants from the used lubricating oil before the main extraction process. By taking out these problematic substances in a dedicated preliminary step, the process protects downstream equipment from fouling while preserving the overall simplicity of the extraction-based re-refining approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves a high yield of high-quality re-refined base oil with reduced solvent consumption and equipment fouling, making it a cost-effective and environmentally safer alternative to hydro-finishing.
Implementation Method 1
injecting into the used lubricating oil fraction a non-hydrogenating heating vapor, and wherein the amount and temperature of the injected heating vapor is sufficient to vaporize at least a portion of the lubricating oil boiling range components
Implementation Method 2
the overhead condenser is operated to condense diesel boiling range components and any water provided water is present
Implementation Method 3
liquid-liquid extraction with a polar organic solvent like N-Methyl-2-Pyrrolidone, which efficiently separates contaminants
Data Source
AI summary
A continuous, hot vapor stripping process recovers base oil from used lubricating oils (ULO) containing lubricating oil boiling range material, with further refining using solvent extraction to produce a high quality base oil. The ULO is charged to a first stripping column along with a stripping vapor to vaporize lubricating oil boiling range components, which are fed to a second stripping column to separate diesel boiling range material from the lubricating oil boiling range components. A lubricating boiling range material is removed as a bottoms product and fed to a liquid-liquid extractor to produce a raffinate stream and an extract stream. The raffinate stream is fed to a raffinate distillation column, where a base oil product is recovered as a bottoms stream. The extract stream is fed to an extract distillation column, where an aromatic oil product is recovered as a bottoms stream.