High-Temperature Safety Valve Seal With Self-Energizing Disc Seat
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Solution Overview
Problem
Safety valves in thermal hydraulic power plants face challenges in maintaining seal tightness under extreme conditions of high pressure and temperature, such as those encountered with Advanced Ultra-Supercritical steam exceeding 760° C (1400° F), which can lead to equipment damage and overpressure issues.
Innovation Solution
A unique disc/seat interface with overlapping geometry that maximizes contact stress and incorporates a flexible, finger-like projection to maintain a metal-to-metal seal, capable of withstanding pressures up to 4200 psi at 1400° F, ensuring self-energizing properties to prevent leakage and maintain seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional safety valve designs are used, then the valve structure is simple and easy to manufacture, but the seal tightness cannot be maintained under extreme high pressure and temperature conditions exceeding 760°C
Solution Approach 1:
The disc/seat interface is segmented into multiple contact zones including a primary sealing surface and a secondary overlapping sealing surface. This segmentation allows each zone to contribute to the overall seal tightness, with the secondary zone providing additional sealing capability under extreme pressure and temperature conditions where conventional single-surface seals fail.
Solution Approach 2:
The invention transitions from a conventional single-plane sealing interface to a multi-dimensional overlapping geometry where the disc contact surface extends beyond the seat opening in radial and axial directions. This dimensional extension creates multiple contact points and areas that maintain seal integrity under thermal expansion and pressure loading that would compromise simpler geometries.
2Reliability
If the disc/seat interface uses overlapping geometry to maximize contact stress, then seal tightness is maintained at set pressure, but the manufacturing precision requirements increase
Solution Approach 1:
The overlapping geometry is designed with specific dimensional parameters including radial extension distance and axial overlap height that are optimized to achieve self-energizing seal enhancement. These parameter changes allow the interface to generate increased contact stress under operating pressure while maintaining manufacturability through standardized geometric relationships rather than arbitrary complex shapes.
Solution Approach 2:
The disc/seat interface is designed to be self-energizing, where the fluid pressure itself acts to increase the contact stress between the overlapping surfaces. The geometry is configured so that pressure differential automatically enhances the sealing force, reducing the need for externally applied pre-load and compensating for manufacturing tolerances through pressure-activated seal enhancement.
3Adaptability or versatility
If a metal-to-metal seal is used to withstand 4200 psi at 1400°F, then the valve can handle extreme operating conditions, but the risk of leakage under rapid overpressure events increases
Solution Approach 1:
The overlapping disc/seat geometry is designed to engage and establish seal contact before full operating pressure is reached. The extended contact surfaces create preliminary sealing engagement that progressively enhances as pressure increases, ensuring the seal is already established and self-energizing before extreme pressures of 4200 psi or rapid overpressure events occur, preventing leakage through proactive seal enhancement.
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 solution effectively maintains seal tightness and prevents fluid flow during non-relieving conditions, even under rapid overpressure events, ensuring the safety valve's reliability and preventing catastrophic damage by adapting to extreme operating conditions.
Implementation Method 1
This geometry incorporates features that can flex or bend under pressure. These features create a more forceful seal that maintains its integrity very near the operating or set pressure for the safety valve.
Implementation Method 2
This interface incorporates overlapping geometry on both the disc and seat that maximizes contact stress at set pressure for the device.
Data Source
AI summary
A safety valve is configured for use at temperatures at or above 760° C. (1400° F.). The safety valve includes a closure assembly that can create a self-energizing, metal-to-metal seal. In one implementation, this closure assembly includes a disc with an arcuate finger that circumscribes an axis of fluid flow through a seat. The arcuate finger may extend inwardly toward this axis and downwardly toward the seat. This geometry permits the finger to flex in response to pressure of fluid that impinges on the downstream side of the disc, such flexure causing a first sealing surface on the disc to more forcefully contact a second sealing surface on a seat.