Refining Used Electrical Insulating Oils via Vacuum Degassing
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Solution Overview
Problem
Current methods for refining used electrical insulating oils fail to produce naphthenic base oils that meet the quality standards for new insulating oils due to issues with oxidative stability and corrosivity, requiring additional processing steps to address volatile and semi-volatile sulphur compounds and other contaminants.
Innovation Solution
A method involving exposing the feed oil to reducing conditions at elevated temperature and pressure, followed by degassing under reduced pressure to prevent oxidation, and extracting the oil with water to produce a refined oil that meets industry standards for transformer oils without further refining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If used electrical insulating oils are refined through conventional methods, then some contaminants are removed, but the product fails to meet quality standards for new insulating oils due to remaining volatile and semi-volatile sulphur compounds and poor oxidative stability
Solution Approach 1:
The patent applies preliminary action by conducting a degassing step under reduced pressure before exposing the oil to oxidizing conditions. This preliminary removal of volatile and semi-volatile sulphur compounds prevents subsequent oxidation reactions that would compromise oxidative stability. The sequence is critical: degassing first, then optional oxidation for contaminant removal, ensuring harmful factors are eliminated before they can generate stability issues.
Solution Approach 2:
The patent employs parameter changes by controlling pressure conditions throughout the process. Reduced pressure is applied during degassing to selectively remove volatile contaminants without causing excessive heating or oxidation. Pressure is then increased when handling the refined oil to prevent re-absorption of volatile compounds. These pressure parameter changes enable selective removal of harmful sulphur compounds while preserving oxidative stability.
2Manufacturing precision
If additional processing steps are added to address volatile sulphur compounds and oxidative stability, then quality standards are met, but process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated refining process. The hydroprocessing reactor simultaneously performs hydrogenation of aromatic compounds, removal of sulphur compounds through degassing under reduced pressure, and neutralization of acidic contaminants using basic nitrogen compounds. This consolidation achieves comprehensive contaminant removal and oxidative stability improvement without requiring separate processing units for each function, thereby reducing overall process complexity while maintaining high product quality.
Solution Approach 2:
The refining process exhibits multi-functionality by using a single hydroprocessing system that performs multiple contaminant removal tasks. The basic nitrogen containing compound serves dual purposes: neutralizing acid sites on catalysts and neutralizing acidic contaminants in the oil. The degassing step under reduced pressure simultaneously removes volatile sulphur compounds and prevents oxidation. This universal approach handles diverse contaminant types through unified process steps rather than dedicated units for each contaminant class.
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
The process effectively reduces contaminants and improves the quality of the refined oil, achieving low volatile and halogen content, low corrosivity, and meeting industry standards for transformer oils, thereby simplifying the production of new naphthenic base oils from used electrical insulating oils.
Implementation Method 1
exposing the feed oil to reducing conditions at elevated temperature and pressure so as to reduce at least some of the contaminants
Implementation Method 2
reducing conditions at elevated temperature and pressure so as to reduce at least some of the contaminants
Implementation Method 3
degassing the resulting oil under reduced pressure before the oil is exposed to any relatively more oxidizing conditions
Implementation Method 4
extracting the resulting oil with water so as to produce a refined oil
Data Source
AI summary
The invention relates to a method for refining a feed oil having contaminants therein. In the method, the feed oil is exposed to reducing conditions at elevated temperature and pressure so as to reduce at least some of said contaminants. The resulting oil is then degassed under reduced pressure under non-oxidizing conditions and the resulting oil extracted with water so as to produce a refined oil.