Piston Ring Seal for Centrifugal Separator Spindle Deflection
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Solution Overview
Problem
Disc stack centrifugal separators face challenges in sealing due to supercritical speed, spindle deflection, and high peripheral speed, which damage conventional sealing materials and allow fluid transfer between housing spaces.
Innovation Solution
A seal comprising a cylindrical inner surface, a circular slot in the spindle or rotating member, and a piston ring that abuts the cylindrical inner surface, allowing for deflection compensation and effective sealing at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastic sealing element abutting against the spindle is used to follow spindle deflection, then sealing effectiveness is improved, but the seal cannot withstand high peripheral speeds up to 50 m/s
Solution Approach 1:
The seal arrangement allows the piston ring to dynamically follow the deflecting spindle during rotation. The piston ring is held against the cylindrical inner surface by a spring, enabling it to adapt to spindle deflection while withstanding high peripheral speeds through controlled contact and reduced friction
Solution Approach 2:
The invention changes the sealing mechanism from static elastic material contact to dynamic piston ring contact with controlled pressure. The spring-loaded piston ring maintains optimal contact pressure with the deflecting spindle surface, allowing effective sealing at high speeds where conventional elastic seals fail
2Strength
If a U-shaped PTFE ring with space between the ring and spindle is used, then damage from spindle deflection is avoided, but fluid transfer between housing spaces occurs
Solution Approach 1:
The piston ring acts as an intermediary element between the spindle and the housing. It follows the spindle deflection while maintaining continuous contact with the cylindrical inner surface, preventing fluid transfer that would occur with spaced PTFE rings
Solution Approach 2:
The piston ring functions as a flexible sealing element that can deform and follow the spindle's deflection path. Unlike rigid or spaced seals, the piston ring maintains conformal contact with the deflecting spindle surface, ensuring reliable sealing
3Device complexity
If the spindle is only journalled at one axial end portion, then bearing arrangement simplicity is improved, but spindle deflection increases at high speeds
Solution Approach 1:
The invention extracts the deflection compensation function from the bearing arrangement itself. By using a spring-loaded piston ring that actively follows spindle deflection, the system compensates for alignment changes without adding multiple fixed bearing positions, maintaining simplicity while improving stability
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 seal effectively withstands spindle deflection and high peripheral speeds, preventing fluid transfer between housing spaces, even at speeds up to 50 m/s, ensuring efficient separation of fluid phases.
Implementation Method 1
The piston ring is resilient and biased outwardly against the cylindrical inner surface
Implementation Method 2
a disc stack centrifugal separator for separating a light fluid phase and a heavy fluid phase from a fluid feed mixture
Data Source
AI summary
A centrifugal separator includes a housing, a spindle, and a rotor. The spindle is only journaled in a bearing arrangement fixedly positioned in the housing at the first axial end portion. The centrifugal separator includes a seal arranged between the spindle and the housing. The seal is arranged at a distance from the bearing arrangement where the spindle is subjected to deflection. The seal includes a cylindrical inner surface associated with the housing, a circular slot in the spindle or in a rotating member associated with the spindle, and a piston ring arranged in the slot and abutting against the cylindrical inner surface.