Insulating Seal Ring for Hydrogen-Cooled Rotor Shaft
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Solution Overview
Problem
Hydrogen-cooled dynamoelectric machines face issues with shaft currents causing electrical pitting and high temperatures leading to oil coking and corrosion in traditional babbitted steel seal rings, which compromise the reliability and safety of the seal systems.
Innovation Solution
The use of electrically insulating or non-metallic seal rings, such as those made from polyether ether ketone, which are resiliently joined around the rotor shaft with tapered surfaces and biased by springs to form a 360° seal, effectively reducing electrical conductivity and withstanding high temperatures, thereby preventing electrical pitting and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional babbitted steel seal rings are used, then sealing effectiveness is maintained, but electrical pitting and corrosion occur due to shaft currents and high temperatures
Solution Approach 1:
The patent changes the material parameter of the seal ring from conductive babbitted steel to electrically insulating materials such as carbon graphite or resin-bonded graphite. This material substitution eliminates electrical conductivity while maintaining mechanical sealing properties, thereby preventing shaft current-induced electrical pitting and corrosion without compromising seal effectiveness
Solution Approach 2:
The patent employs composite material structures, specifically carbon graphite or resin-bonded graphite compositions. These composite materials combine the electrical insulating properties of carbon with the binding characteristics of resins or metallic matrices, creating a seal ring that simultaneously provides electrical insulation, mechanical strength, and sealing functionality to prevent both electrical and thermal damage
2Strength
If babbitted steel seal rings are used, then structural strength is provided, but high temperatures cause oil coking and hot corrosion
Solution Approach 1:
The patent changes the thermal parameter resistance by selecting materials with superior high-temperature stability. Carbon graphite and resin-bonded graphite materials maintain their structural integrity and mechanical properties at elevated temperatures where traditional babbitted steel would experience oil coking and hot corrosion, thereby eliminating temperature-related degradation
Solution Approach 2:
The patent adopts carbon graphite seal rings that can operate in high-temperature environments without the need for continuous oil cooling. These materials withstand thermal conditions that would otherwise require complex cooling systems and frequent maintenance of babbitted steel rings, effectively replacing a maintenance-intensive solution with a more durable material
3Object-affected harmful factors
If electrically insulating seal rings are used, then electrical pitting is reduced, but material selection becomes more limited
Solution Approach 1:
The patent identifies carbon graphite and resin-bonded graphite as universal materials that simultaneously provide electrical insulation, mechanical strength, sealing capability, and high-temperature resistance. These multi-functional materials replace the need for separate insulating components and complex material combinations, offering a single solution that addresses electrical pitting prevention while maintaining all necessary mechanical and thermal properties
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 implementation of electrically insulating seal rings significantly reduces electrical pitting, enhances durability against high temperatures, and maintains the integrity of the seal system, ensuring safer and more reliable operation of hydrogen-cooled dynamoelectric machines by eliminating hot corrosion and improving hydrogen seal efficiency.
Implementation Method 1
The seal ring comprises an electrically insulating material or a non-metallic material
Implementation Method 2
The seal ring is resiliently joined about the shaft to form a seal
Implementation Method 3
The first seal ring and the second seal ring have adjacent tapered surfaces, and the springs are configured to be seated against the adjacent tapered surfaces
Data Source
AI summary
A seal ring assembly for a rotor shaft includes a seal casing defining a radially inwardly directed channel. The seal ring is disposed in the radially inwardly directed channel of the seal casing. The seal ring is resiliently joined about the shaft to form a seal, and the seal ring comprises an electrically insulating or dissipative material or a non-metallic material.