Centrifugal Pump Seal Leakage Detection

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Solution Overview

Problem

Multi-stage centrifugal pumps face challenges in achieving tightness at high pressure areas, leading to increased friction and reduced efficiency and seal life, as existing mechanical seals struggle to balance leakage prevention with operational efficiency.

Innovation Solution

A ring-shaped container is placed around the shaft to collect and monitor liquid leakage through the seal, using electrically insulated contacts to detect fluid presence and level, allowing for controlled leakage and early detection of seal wear, thereby reducing friction and extending seal life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the contact pressure of the seal is increased to prevent liquid escape, then sealing tightness is improved, but frictional forces increase and efficiency decreases

Engineering Contradiction:
Improvesealing tightnessVSAvoidfrictional forces
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by intentionally allowing a small, controlled amount of liquid to pass through the seal rather than achieving complete tightness. This controlled leakage is monitored by the detection system, which enables the seal to operate at lower contact pressure, thereby reducing frictional forces and improving efficiency while maintaining acceptable sealing performance.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If the sealing gap is reduced to prevent liquid escape, then sealing tightness is improved, but frictional forces increase and wear accelerates

Engineering Contradiction:
Improvesealing tightnessVSAvoidseal service life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent intentionally allows partial liquid passage through the seal rather than achieving complete tightness. This controlled leakage is monitored by the detection system, enabling the seal to operate with reduced friction and wear, thereby extending seal service life while maintaining acceptable sealing performance.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent incorporates a detection system with electrical contacts that monitor liquid passage through the seal. This feedback mechanism detects when liquid begins to pass through the sealing gap, providing early warning of seal wear. The system enables proactive maintenance before complete seal failure occurs, extending the effective service life of the seal.

Inventive Principle:
Principle #23Feedback

3Reliability

If complete tightness is achieved through high contact pressure, then liquid escape is prevented, but efficiency decreases due to increased friction

Engineering Contradiction:
Improvesealing tightnessVSAvoidpump efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent deliberately accepts partial liquid passage through the seal rather than achieving complete tightness. The detection system monitors this controlled leakage, allowing the seal to operate at optimal contact pressure that balances sealing performance with minimal friction, thereby maintaining high pump efficiency.

Inventive Principle:
Principle #16Partial or excessive action

4Reliability

If the seal is designed for complete tightness, then liquid escape is minimized, but detection of seal wear becomes more difficult

Engineering Contradiction:
Improvesealing tightnessVSAvoidseal wear detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent incorporates a feedback-based detection system with electrical contacts positioned to detect liquid passage through the seal. As the seal wears and liquid begins to pass through the sealing gap, the liquid conducts electricity between the contacts, triggering an alarm signal. This feedback mechanism provides early warning of seal wear while the seal maintains complete tightness during normal operation.

Inventive Principle:
Principle #23Feedback

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

This solution enables efficient operation by reducing frictional forces, increasing seal life, and providing reliable function monitoring, applicable to various types of seals, including mechanical and O-rings, while allowing a controlled amount of leakage to maintain pump efficiency.

Implementation Method 1

at least two contacts which are electrically insulated from one another and which are electrically conductively connected by the liquid are provided

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2669525B1Centrifugal pump assembly
Publication Date: 2018.01.24 GRUNDFOS HLDG
  • EP2669525B1 patent drawingFigure 1
  • EP2669525B1 patent drawingFigure 2~3
  • EP2669525B1 patent drawingFigure 4

AI summary

The centrifugal pump has an impeller that is rotatably mounted on a shaft, which is sealed off by seal (11) to a surrounding housing. The seal is opened towards a container (12) for the collection of the fluid, and is configured to detect fluid in or out of the container. The container is annular and is configured to surround the shaft. A sensor (20) configured for detecting the flow rate of drops. A discharge opening is followed by the tubes (21,22) formed by the sensor whose other end is open to the outside or to a discharge line.