Transformer Drying via Solvent Vapor Condensation
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Solution Overview
Problem
Existing methods for drying transformers with solid insulation impregnated in oil are inefficient due to high energy requirements, long throughput times, and residual moisture issues, particularly in oil-spray drying processes which achieve insufficient insulation temperatures and prolonged drying times.
Innovation Solution
A method involving the initial heating of the transformer's active part using solvent vapor condensation, followed by post-heating with warm spray oil to efficiently evaporate remaining solvent and moisture, reducing drying time and energy consumption, and eliminating the need for expensive thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solvent vapor is generated outside the transformer housing and conducted via flexible lines, then the drying process can be performed, but the process requires a lot of energy and large amount of equipment
Solution Approach 1:
The solvent vapor generator is integrated directly inside the transformer housing, merging the heating function with the drying chamber. This eliminates the need for external vapor generation and flexible connection lines, reducing energy loss and equipment complexity while maintaining effective solvent vapor delivery to the insulation
Solution Approach 2:
The housing walls themselves serve as the intermediary medium for heat transfer. The heating element mounted on the inner wall directly heats the housing structure, which then transfers heat to the insulation and solvent, eliminating the need for separate external heating systems and flexible vapor delivery lines
2Reliability
If heated spray oil is continuously sprayed over the solid insulation in a circulation process, then moisture is evaporated from the insulation, but the drying time is prolonged and energy requirement is high
Solution Approach 1:
The spray oil circulation is replaced by periodic solvent vapor injection cycles. The solvent vapor is introduced in controlled intervals, allowing rapid heating and moisture evaporation during each cycle, followed by vacuum removal of evaporated moisture. This periodic approach achieves thorough drying faster than continuous spray oil circulation
Solution Approach 2:
The process changes from using spray oil at moderate temperatures to using solvent vapor at higher temperatures. The solvent vapor delivers concentrated thermal energy quickly, raising the insulation temperature rapidly to accelerate moisture evaporation, thereby reducing overall drying time compared to gradual heating with spray oil
3Productivity
If the housing is evacuated and solvent vapor is used for heating, then water escapes from the insulation effectively, but expensive thermal insulation is required to maintain temperature
Solution Approach 1:
The vacuum system serves a dual function: it removes evaporated moisture during the heating phase and then maintains the drying atmosphere after heating stops. The housing structure itself, when evacuated, prevents heat loss to the external environment, eliminating the need for additional thermal insulation while maintaining effective drying temperatures
Solution Approach 2:
The evacuated housing creates a vacuum environment that serves as an inert atmosphere, preventing heat transfer to the external environment and eliminating the need for thermal insulation. The vacuum also prevents oxidation and maintains the drying process efficiency without requiring additional insulation materials
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 significantly shortens drying time, reduces energy requirements, and achieves low residual moisture in the solid insulation, enhancing the efficiency and economy of the drying process without the need for extensive thermal insulation.
Implementation Method 1
the heat of condensation of a solvent vapor is used to quickly and gently heat up the active part
Implementation Method 2
solvent vapor generated during the drying process in the solvent vapor generator is conducted via the flexible solvent vapor lines into a transformer housing and condenses on the solid insulation
Implementation Method 3
the active part is installed in the vacuum-tight housing of the device and is kept at negative pressure
Implementation Method 4
moisture is evaporated from the solid insulation and sucked off with a vacuum system together with the spray oil vapor
Data Source
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AI summary
Water, contaminated impregnating and active portion of housing device after evacuation of housing is heated by condensation of solvent vapor which is formed by vaporizing solvent within and/or outside of housing. A mixed vapor flow is formed during heating, and water and solvent are separated. The heated active portion is dried under vacuum pressure, solid isolation of active portion is cooled and reheated by spraying heated spray oil on the surfaces of solid insulation. Thus, method for drying solid isolation containing active portion of electronic device is enabled. An independent claim is included for device.