Magnetic Dry Gas Seal Control Without Buffer Gas Support
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Solution Overview
Problem
Dry gas seals in rotating machinery fail due to operational difficulties such as contamination and imbalances in the buffer gas supply system, leading to contact between seal faces and subsequent material failure, especially when the dynamic gas film breaks down.
Innovation Solution
Active control of the axial separation between the seal faces using magnetic devices and sensors, allowing for adjustment of the net magnetic force to maintain clearance without a buffer gas, thereby controlling the flow of gas or fluid between the seal faces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer gas supply system is used to maintain separation between seal faces, then the seal faces are protected from contact, but the system becomes vulnerable to contamination and operational failures
Solution Approach 1:
The patent removes the buffer gas supply system entirely and replaces it with magnetic devices that directly control the axial position of the rotating ring. This extraction of the buffer gas system eliminates contamination risks while maintaining seal face separation through magnetic force control.
Solution Approach 2:
The patent replaces the mechanical buffer gas supply system with a magnetic control system. Magnetic devices generate magnetic forces that act on the rotating ring to maintain axial separation, substituting the mechanical gas pressure-based system with a magnetic field-based system that is less susceptible to contamination.
2Device complexity
If the dynamic gas film is relied upon to prevent seal face contact, then the seal operates with simpler structure, but the seal faces contact when the film breaks down due to contamination
Solution Approach 1:
The magnetic devices continuously apply magnetic forces to maintain axial separation between seal faces before contamination can cause the gas film to break down. This preliminary action prevents face contact proactively rather than reacting after contamination occurs.
Solution Approach 2:
The patent employs sensors to detect the axial separation between seal faces and feeds this information back to the magnetic control system. This feedback mechanism allows real-time adjustment of magnetic forces to maintain optimal separation, ensuring reliability even when gas film conditions change due to contamination.
3Reliability
If buffer gas is used to maintain seal face clearance, then the seal faces remain separated, but the buffer gas system requires additional power and creates contamination risks
Solution Approach 1:
The patent replaces the power-intensive buffer gas compression and supply system with magnetic devices that generate magnetic fields to control axial separation. Magnetic fields require significantly less power to maintain the same level of control over seal face clearance.
Solution Approach 2:
By removing the buffer gas supply system entirely and using magnetic control, the patent eliminates the power consumption associated with gas compression, filtration, and supply infrastructure while maintaining reliable seal face clearance.
4Reliability
If the seal system uses buffer gas to prevent face contact, then face separation is maintained, but the system becomes sensitive to reverse pressurization and imbalances
Solution Approach 1:
The magnetic control system dynamically adjusts the magnetic forces applied to the rotating ring based on real-time feedback from sensors. This dynamic control allows the system to adapt to varying operating conditions, including reverse pressurization and gas composition changes, maintaining face separation across a broader range of conditions than the static buffer gas system.
Solution Approach 2:
The feedback control mechanism continuously monitors axial separation and adjusts magnetic forces in real-time, enabling the system to adapt to reverse pressurization and imbalances that would disrupt the static buffer gas system. This feedback loop provides the adaptability needed to maintain reliable face separation under varying conditions.
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 solution prevents seal face contact and failure by maintaining a stable clearance, even in conditions where the dynamic gas film is lost, improving functional performance and reducing the risk of contamination-induced overheating, while eliminating the need for a buffer gas system, which reduces complexity and power requirements.
Implementation Method 1
a magnetic device configured to generate a magnetic field to apply a magnetic force on the rotating ring
Implementation Method 2
a sensor configured to detect an axial separation distance between the stationary and rotating seal faces
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method and system for actively controlling an axial separation between a seal face of a stationary ring (16) and a seal face of a rotating ring (14) of a gas seal (10) is disclosed. At least one property is sensed indicative of a condition of at least one of the seal faces. With at least one sensing device (30), a characteristic of the axial separation between the seal faces is sensed. A net magnetic force of at least one magnetic device (24) is adjusted based on the property and/or the characteristic. Adjusting the net magnetic force adjusts the axial separation between the seal faces. Without using a buffer gas between the seal faces, flow of gas or other fluid is controlled between the seal faces by adjusting the axial separation.