SF6 Regeneration Filter Train for On-Site Purification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for regenerating sulfur hexafluoride (SF6) gas in electrical transformers are inadequate as they do not effectively eliminate all pollutants, leading to logistical constraints and high regeneration costs, especially when pollutant levels exceed 1.26% by mass, necessitating on-site regeneration solutions.
Innovation Solution
A device comprising a series of filters, including a bed of soda lime, activated carbon, activated alumina, and a molecular sieve, arranged in a specific sequence to eliminate pollutants in SF6 gas, allowing for effective on-site regeneration of SF6 gas by passing the fluid through these filters in series, ensuring the removal of all conventional pollutants encountered in transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single filter or limited filters are used for SF6 regeneration, then the device complexity is reduced, but the purification effectiveness is insufficient as not all pollutants are eliminated
Solution Approach 1:
The purification system is divided into multiple sequential filter stages, each targeting specific pollutant types. The first filter removes particles and liquid drops, the second filter removes acid gases, and the third filter removes remaining pollutants. This segmentation allows each filter to be optimized for its specific function, achieving comprehensive purification while maintaining reasonable device complexity.
Solution Approach 2:
Different filter materials with specific local properties are selected for each stage: a particulate filter for solid/liquid removal, a chemical filter (activated alumina or molecular sieve) for acid gas absorption, and a carbon filter for organic pollutant adsorption. Each filter has localized quality tailored to its specific purification task, ensuring maximum effectiveness for each pollutant type.
2Loss of substance
If SF6 gas with high pollutant content (>1.26% by mass) is regenerated, then the loss of substance is reduced, but the regeneration process becomes more complex and costly requiring factory-level operations
Solution Approach 1:
The system performs preliminary separation of liquid drops and particles before the gas enters the chemical and carbon filters. This preliminary action prevents saturation of the expensive activated alumina and molecular sieve filters by bulk liquids, allowing them to focus on removing dissolved pollutants. This enables effective regeneration even of highly polluted gas while using manageable filter sizes.
Solution Approach 2:
The system changes the physical state consideration by treating SF6 as a compressible gas that can be processed through adsorption and absorption. By utilizing the gas phase properties and applying pressure differential through the filter bed, the system can handle high pollutant concentrations without requiring complex phase change equipment, enabling on-site regeneration of heavily polluted gas.
3Device complexity
If molecular sieve is used alone for pollutant removal, then the device complexity is minimized, but the molecular sieve becomes saturated quickly due to polar and large molecule pollutants
Solution Approach 1:
The particulate filter and chemical filter are positioned upstream to remove particles, liquid drops, and acid gases before the gas reaches the molecular sieve. This preliminary removal of polar and large molecule pollutants prevents rapid saturation of the molecular sieve, extending its service life and maintaining low device complexity.
Solution Approach 2:
The activated alumina or carbon filter acts as an intermediary between the highly polluted SF6 and the molecular sieve. It absorbs or adsorbs the most aggressive pollutants (acid gases, polar molecules) that would otherwise quickly saturate the molecular sieve, allowing the molecular sieve to focus on removing remaining trace pollutants and extending its operational duration.
4Loss of time
If on-site regeneration is implemented, then the loss of time and logistical constraints are reduced, but the device complexity and initial cost increase
Solution Approach 1:
The filter assembly is designed as a universal unit that can handle the full range of SF6 pollutants encountered in electrical equipment. The combination of particulate, chemical, and carbon filters creates a multi-functional system that can process SF6 from various sources and pollution levels, justifying the initial complexity investment by eliminating repeated factory trips and downtime.
Solution Approach 2:
The system enables the electrical equipment operator to perform SF6 regeneration independently on-site without requiring external factory services. The standardized filter cartridges can be easily replaced by operators, making the system self-sufficient and reducing both time loss and logistical dependencies on external regeneration facilities.
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 proposed solution enables the efficient elimination of all pollutants in SF6 gas, including polar and large molecules, preventing saturation of the molecular sieve and ensuring optimal adsorption, thus allowing for effective on-site regeneration within the specified pollutant limit, reducing logistical and operational costs.
Implementation Method 1
a first filter comprising a bed of soda lime and/or activated carbon
Implementation Method 2
a second filter comprising activated alumina
Implementation Method 3
a third filter comprising a molecular sieve
Data Source
Figure 1
Figure 2~4
Figure 3
AI summary
The device comprises a closed chamber (4) provided with a series of filters arranged in series on a path followed by a fluid within the chamber. The first filter has a bed of soda-lime and/or activated carbon. The second filter comprises activated alumina. The third filter comprises a molecular sieve. The device further comprises: a bed of activated carbon; a particle filter arranged downstream of the third filter and to the path followed by the fluid; and a unit (3) for moving the fluid through the chamber. The bed of soda lime is placed upstream of the activated carbon bed. The device comprises a closed chamber (4) provided with a series of filters arranged in series on a path followed by a fluid within the chamber. The first filter has a bed of soda-lime and/or activated carbon. The second filter comprises activated alumina. The third filter comprises a molecular sieve. The device further comprises: a bed of activated carbon; a particle filter arranged downstream of the third filter and to the path followed by the fluid; and a unit (3) for moving the fluid through the chamber. The bed of soda lime is placed upstream of the activated carbon bed. The activated alumina bed is positioned downstream of the bed of soda lime and upstream of the bed of activated carbon. The bed of soda lime has a thickness that is twice of its width. The bed of activated carbon has a thickness of >= 60 cm. The bed of activated alumina has a thickness that is twice of its width. The molecular sieve has a thickness that is twice of its width, and a diameter of 4-5 Å . An independent claim is included for a method for regenerating, in a liquid phase, sulfur hexafluoride used to form an inert atmosphere in a closed chamber.