Vapor-Phase Drying of Transformer Insulation Using Multi-Stage Solvent Injection
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Solution Overview
Problem
Existing methods for drying the solid insulation of electrical transformers using the vapor phase method are inefficient due to reduced heating capacity and longer drying times, especially in transformers with small drain connections, as they limit the circulation and heating of solvent, leading to insufficient drying temperatures and prolonged drying processes.
Innovation Solution
A multi-stage injection method where superheated solvent is injected into interconnected evaporator stages within a flow channel, creating turbulence and ensuring efficient mixing of solvent vapor, allowing for quicker and more uniform heating of the solid insulation, while also utilizing a fine vacuum phase for post-heating to maintain high efficiency and quality of drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heated solvent is circulated into the transformer housing to dry the solid insulation, then the insulation is heated and moisture is evaporated, but the heating capacity is reduced and drying time is prolonged in transformers with small drain connections
Solution Approach 1:
The patent utilizes phase transition of solvent from liquid to vapor form. The solvent is heated to generate solvent vapor that penetrates the solid insulation, and then condensed back to liquid form to extract moisture. This phase transition mechanism enables efficient moisture removal without being constrained by drain connection size, as the vapor-phase solvent can diffuse throughout the insulation structure.
Solution Approach 2:
The patent changes the physical state parameter of the solvent from liquid to vapor phase for the drying process. By operating in vapor phase, the solvent can penetrate and circulate through the solid insulation more effectively, maintaining high heating capacity even with small drain connections, thus resolving the contradiction between productivity and time loss.
2Power
If solvent circulation is limited due to small drain connections, then the heating capacity is reduced, but increasing circulation requires larger drain connections
Solution Approach 1:
The invention employs phase transition of solvent between liquid and vapor states. The solvent is vaporized to increase its circulation capability within the transformer housing, allowing sufficient heating capacity to be achieved without requiring large drain connections. The vapor phase enables better penetration and distribution throughout the solid insulation structure.
3Temperature
If heated solvent is injected to rapidly heat the solid insulation, then drying temperature is achieved faster, but energy consumption increases
Solution Approach 1:
The patent utilizes the latent heat of vaporization and condensation of the solvent. When the solvent vapor condenses on the solid insulation, it releases latent heat that efficiently raises the insulation temperature. This phase transition-based heating mechanism achieves rapid temperature increase with optimized energy consumption, as the heat transfer during condensation is highly efficient.
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 reduces drying time and energy requirements by ensuring uniform heating and precise temperature control, while maintaining high solvent circulation efficiency even with small drain nozzles, thereby improving the overall drying process and quality.
Implementation Method 1
superheated solvent is evaporated in a flow channel which has at least one suction opening arranged in the vacuum container and one outlet opening arranged in the vacuum container
Implementation Method 2
the active part is heated by condensation of saturated solvent vapor in at least one heating-up phase at negative pressure
Implementation Method 3
the resulting mixed vapor containing at least solvent and water vapor is extracted by condensation from a vacuum container accommodating the active part
Implementation Method 4
the active part is kept under negative pressure during the process
Implementation Method 5
the circulation speed of a mixed vapor flow formed when the solid insulation is heated and containing solvent and water vapor is greatly increased, which leads to good heat transfer to the active part of the transformer
Implementation Method 6
creating turbulence and ensuring efficient mixing of solvent vapor, allowing for quicker and more uniform heating of the solid insulation
Data Source
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AI summary
The process serves to dry the solid insulation of the active part (1.1) of an electrical device, which contains water, and optionally insulating oil and impurities, using the vapor-phase method. In this process, superheated solvent is evaporated in an evacuated flow channel, generating a solvent saturated vapor jet (3.9). To increase the efficiency of the process, a first portion of the superheated solvent is injected into a first section (3) of the flow channel, generating a first solvent saturated vapor jet (3.9), and a remaining second portion of the heated solvent is injected into a second section (3.2) of the flow channel, generating a second solvent saturated vapor jet (3.9). At the point of generation (3.2.2) of the second solvent saturated vapor jet (3.9), the following flows have the same direction: (a) the first solvent saturated vapor jet, (b) through the first intake opening (3.1) drawn-in mixed steam (10), (c) drawn-in mixed steam (3.10) through a second intake opening (3.2.1) and (d) the second solvent saturated steam jet.