Composite Backup Rings for High-Pressure Compressor Sealing
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Solution Overview
Problem
High differential pressures in high-pressure gas processing equipment, such as reciprocating compressors, lead to increased wear on seals, reduced reliability, and undesired gas emissions, making it difficult to maintain effective sealing.
Innovation Solution
A packing case with composite backup rings, comprising regions of different materials like polymers and metals, is used to inhibit seal extrusion and enhance sealing performance, with specific rings activating at different pressure levels to manage varying operational pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high differential pressure is maintained in the system, then the system can operate at higher working pressures as required by customer specifications, but sealing becomes more difficult and gas containment deteriorates
Solution Approach 1:
The sealing system is divided into multiple sealing stages along the piston rod, with each stage handling a portion of the pressure differential. This segmentation allows the system to maintain high overall differential pressure while each individual seal operates within manageable pressure limits, improving gas containment reliability.
Solution Approach 2:
The backup rings are constructed from composite materials with different regions having different material properties. The inner region uses a non-metallic material for compliance and sealing, while the outer region uses metal for structural strength and extrusion resistance. This composite structure enables the sealing system to effectively contain high differential pressures.
2Stress or pressure
If high differential pressure is maintained, then working pressure capacity increases, but wear on seal components increases
Solution Approach 1:
The composite backup rings combine non-metallic inner regions for wear-resistant sealing contact with metallic outer regions for structural support. This material combination reduces wear on seal components by distributing mechanical stresses appropriately, thereby extending seal component life while maintaining high working pressure capability.
Solution Approach 2:
Different regions of the backup ring are assigned different material properties tailored to local functional requirements. The inner region contacts the piston rod and requires wear-resistant non-metallic material, while the outer region requires metal for extrusion resistance. This local optimization reduces overall wear and extends component life.
3Stress or pressure
If high differential pressure is maintained, then system pressure capacity improves, but lubrication oil consumption increases
Solution Approach 1:
The non-metallic inner region of the backup ring provides a low-friction sealing surface that reduces lubrication oil consumption. By using materials with inherently low coefficients of friction in the contact zone, the system maintains high pressure capacity while minimizing lubrication requirements.
4Stress or pressure
If high differential pressure is maintained, then working pressure increases, but gas emissions to atmosphere increase
Solution Approach 1:
The progressive multi-stage sealing system segments the pressure containment function across multiple sealing zones. Each stage prevents gas leakage at a different pressure level, collectively eliminating gas emissions to atmosphere while maintaining high system pressure capacity.
Solution Approach 2:
The composite backup rings provide enhanced sealing effectiveness through their dual-material construction, preventing gas penetration through the sealing interface even under high differential pressure conditions, thereby eliminating harmful gas emissions.
Data Source
AI summary
A packing case for a gas compressor includes two or more progressive seals. At least one of the two or more progressive seals includes a packing cup, one or more seal rings at least partially disposed in the packing cup, and one or more backup rings. At least one of the seal rings includes two or more segments each including a pair of opposing ends. The ends of each pair of the adjacent segments define a joint between the segments. At least one of the backup rings including two or more regions. At least one of the regions includes a different material than at least one of the other regions.