PTFE-PEEK Piston Ring Composition for Sulfur-Free Hydrogen Sealing
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Solution Overview
Problem
Piston rings without polyphenylene sulfide (PPS) used in reciprocating compressors for hydrogen stations have shorter life, leading to difficulty in maintaining sealing performance over long periods, which can result in sulfur contamination of hydrogen gas and affect fuel cell efficiency.
Innovation Solution
A piston ring composed of polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) or polyimide, accounting for 50% or more by mass, with a tensile strength between 15 MPa and 100 MPa, is used to prevent sulfur contamination and maintain sealing performance, and a method to evaluate the life of the piston ring based on pressure changes due to gas leakage is implemented.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piston ring containing PPS is used, then sealing performance is maintained, but sulfur component contaminates the compressed hydrogen gas
Solution Approach 1:
The harmful sulfur-containing PPS material is extracted and removed from the piston ring composition. The invention replaces PPS with alternative materials (PTFE combined with PEEK or PI) that provide sealing functionality without sulfur contamination, thus eliminating the harmful factor while preserving the sealing function.
Solution Approach 2:
The invention uses a composite material system where PTFE (providing low friction and chemical inertness) is combined with PEEK or PI (providing mechanical strength and thermal stability). This composite achieves the sealing performance previously provided by PPS without the sulfur contamination issue, resolving the contradiction between sealing reliability and contamination prevention.
2Object-generated harmful factors
If a piston ring containing no PPS is used, then sulfur contamination is suppressed, but sealing performance deteriorates over time
Solution Approach 1:
The patent employs a composite material formulation where PTFE (5-40 mass%) provides low friction and chemical resistance, while PEEK or PI (45-90 mass%) provides mechanical strength and dimensional stability. This composite structure maintains sealing performance over time without PPS, preventing both sulfur contamination and sealing deterioration.
Solution Approach 2:
The invention optimizes specific parameters including the ratio of PTFE to PEEK/PI (5-40 mass% to 45-90 mass%), tensile strength (15-100 MPa), and material composition to achieve the desired balance. By carefully controlling these parameters, the piston ring maintains adequate sealing performance without PPS, preventing both sulfur contamination and premature sealing failure.
3Strength
If a piston ring with high tensile strength is used, then mechanical strength is improved, but sealing performance decreases
Solution Approach 1:
The patent identifies and optimizes the tensile strength parameter within a specific range (15-100 MPa) to balance mechanical strength and sealing performance. By controlling the material composition (PTFE 5-40 mass%, PEEK or PI 45-90 mass%) and processing conditions, the invention achieves adequate tensile strength while maintaining the flexibility and conformability needed for effective sealing.
Data Source
AI summary
A piston ring is used for a reciprocating compressor. In the piston ring, polytetrafluoroethylene and polyetheretherketone or polyimide account for 50% or more by mass in total. The piston ring does not contain polyphenylene sulfide. The piston ring has a tensile strength within a range of more than 15 MPa and less than 100 MPa.