Pressure-Balanced Floating Seal Housing for Rotary Blowout Preventers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-pressure rotary seals in large machinery, such as rotary blowout preventers, face challenges with shaft-to-housing contact due to manufacturing tolerances and thermal expansion, leading to seal damage and misalignment, which compromises the seal's extrusion resistance and longevity.
Innovation Solution
A pressure-balanced floating seal housing arrangement that uses applied pressure to provide hydraulic force balance, allowing the seal housing to translate laterally and accommodate shaft deflection and runout without requiring a stepped shaft diameter, thus preventing damaging contact and maintaining seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a small extrusion gap clearance is used to improve extrusion resistance, then seal extrusion resistance is improved, but shaft-to-housing contact occurs due to manufacturing tolerances and thermal expansion
Solution Approach 1:
The seal housing is made laterally movable relative to the shaft through a floating mounting arrangement, allowing the housing to dynamically adjust its position to accommodate shaft deflection and runout while maintaining the small extrusion gap clearance needed for extrusion resistance
Solution Approach 2:
A bearing assembly is introduced as an intermediary component between the shaft and seal housing, providing precise radial location of the housing while allowing controlled lateral movement to prevent shaft-to-housing contact at the extrusion gap
2Productivity
If large machinery components are used, then equipment capacity is improved, but manufacturing tolerances and thermal expansion cause shaft misalignment and contact
Solution Approach 1:
The seal housing transitions from a fixed to a floating movable mounting, enabling it to accommodate the dimensional variability and misalignment inherent in large machinery components while maintaining proper seal clearance
Solution Approach 2:
The system allows controlled changes in the positional parameters of the seal housing relative to the shaft, enabling adaptation to thermal expansion and manufacturing tolerances in large equipment
3Device complexity
If a non-floating seal housing is used, then structural simplicity is improved, but stack alignment must be essentially perfect
Solution Approach 1:
The seal housing is designed with floating movable mounting that allows lateral movement to compensate for misalignment, maintaining structural simplicity while eliminating the need for perfect stack alignment
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 prevents seal damage by maintaining a stable extrusion gap and minimizing pressure-induced deformation, ensuring prolonged seal life and reliable pressure control in high-pressure environments.
Implementation Method 1
uses applied pressure to provide hydraulic force balance, allowing the seal housing to translate laterally
Implementation Method 2
allowing the seal housing to translate laterally to follow shaft deflection and runout
Implementation Method 3
Minimal pressure induced deformation ('pressure breathing') of the extrusion gap clearance
Data Source
AI summary
A dynamic sealing mechanism for a machine assembly that includes a seal housing of generally cylindrical form having opposed ends, the seal housing axially positioned between a pressure housing and a retaining member and laterally translatable relative to the pressure housing. The dynamic sealing mechanism includes a shaft located at least partially within the seal housing, the shaft having a sealing surface of generally cylindrical form, relatively movable with respect to the seal housing, and having at least one radial bearing positioned radially by the shaft and locating the radial position of the seal housing. At least three fluid pressure-generated forces act axially on the seal housing to produce a net fluid pressure-generated axial force that is negligible.