Seal Stack Assembly for Cryogenic Pump Pressure Sealing
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Solution Overview
Problem
Traditional seal stack assemblies fail to maintain an effective seal at extreme operating conditions such as cryogenic temperatures and elevated pressures, particularly in applications like liquid hydrogen reciprocating pumps.
Innovation Solution
A seal stack assembly comprising a combination of first, second, and third annular seals, along with a spacer, designed to provide a continuous annular seal between a housing and a shaft, utilizing specific seal configurations and materials to withstand cryogenic temperatures and pressures, including energizing springs and support rings for enhanced sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional seal stack assemblies are used, then the structure is simple and easy to manufacture, but the sealing reliability fails at extreme operating conditions such as cryogenic temperatures and elevated pressures
Solution Approach 1:
The seal stack assembly is divided into multiple individual seal elements (primary seal, secondary seal, tertiary seal) arranged in series along the shaft. Each seal element is independently configured to handle specific portions of the sealing challenge, allowing the system to maintain reliability under extreme conditions while keeping each individual component relatively simple and manufacturable.
Solution Approach 2:
The patent employs composite sealing structures combining different materials with complementary properties. The seal elements utilize combinations of elastomers, polymers, and metal components that work together to provide both flexibility for sealing and structural integrity under cryogenic temperatures and high pressures, resolving the contradiction between reliability and manufacturing complexity.
2Reliability
If multiple individual seals are used in a seal stack assembly, then sealing reliability improves under extreme conditions, but the device complexity and number of components increases
Solution Approach 1:
Multiple seal elements are merged into a single integrated seal stack assembly that functions as one cohesive unit. The primary seal, secondary seal, and tertiary seal are arranged in a compact configuration along the shaft, reducing the overall complexity of assembly and maintenance while maintaining the reliability benefits of multiple sealing barriers.
Solution Approach 2:
The seal stack assembly is designed with multi-functional components that serve multiple purposes. For example, the seal elements not only provide sealing but also compensate for thermal contraction, accommodate shaft movement, and distribute pressure loads, thereby reducing the need for additional specialized components and simplifying the overall system.
3Reliability
If seals are designed to withstand cryogenic temperatures and elevated pressures, then sealing reliability improves, but the manufacturing precision and material selection requirements increase
Solution Approach 1:
The seal elements are designed with specific geometric parameters and material properties optimized for cryogenic service. The cross-sectional shapes, hardness values, and dimensional tolerances are carefully selected to ensure proper sealing function at low temperatures where materials exhibit different mechanical properties, thereby achieving reliability without excessive manufacturing complexity.
Solution Approach 2:
Different portions of the seal stack assembly have locally optimized properties tailored to their specific functional requirements. The sealing surfaces have precise finish requirements, while other portions have more relaxed tolerances. This localized approach to quality control ensures sealing integrity at critical interfaces while reducing overall manufacturing precision requirements for non-critical components.
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 ensures a reliable and continuous annular seal across a wide temperature range (from room temperature to cryogenic temperatures) and at elevated pressures, maintaining sealing integrity during operation and changes in pressure or temperature.
Implementation Method 1
energizing springs for enhanced sealing performance
Implementation Method 2
designed to provide a continuous annular seal between a housing and a shaft, utilizing specific seal configurations and materials to withstand cryogenic temperatures and pressures
Data Source
AI summary
Systems and methods include providing an annular seal stack for an assembly. The seal stack assembly includes, at least one second annular seal, a spacer disposed axially adjacent to the at least one second annular seal, and a third annular seal disposed axially adjacent to the spacer. The seal stack assembly is disposed between a probe and a housing of the assembly and configured to provide an annular seal between the probe and the housing during operation of the assembly at cryogenic temperatures, during exposure of at least a portion of the seal stack assembly to cryogenic temperatures, during a change in pressure, during a change in temperature, or a combination thereof.