Centrifugal Pump Seal Carrier Guide Structure
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Solution Overview
Problem
Centrifugal pumps experience dry running conditions during startup, leading to insufficient lubrication and cooling of the shaft seal, which increases wear and can cause material tension and damage, especially in sea water applications where air pockets form around the shaft seal due to centrifugal forces.
Innovation Solution
A guide structure on the seal carrier directs the flow medium from the outer radial area to the inner radial area, counteracting centrifugal forces and ensuring lubrication and cooling of the shaft seal, particularly through an inclined axially projecting guide surface that extends from the outer to the inner radial area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump operates during startup with air pockets forming around the shaft seal due to centrifugal forces, then the liquid flow medium is distributed to the radially outer area, but the shaft seal experiences dry running conditions with insufficient lubrication and cooling
Solution Approach 1:
A guide structure is introduced as an intermediary element between the liquid flow medium and the shaft seal. This guide structure redirects the liquid flow medium from the radially outer area to the radially inner area where the shaft seal is located, ensuring proper lubrication and cooling during startup operation. The guide structure acts as a mediator that overcomes the centrifugal force-induced flow distribution pattern.
2Force
If centrifugal forces act on the liquid flow medium during pump operation, then the liquid is driven to the radially outer area, but air pockets form in the radially inner area around the shaft seal
Solution Approach 1:
The guide structure inverts the natural centrifugal flow pattern by redirecting the liquid flow medium from the radially outer area back to the radially inner area. Instead of allowing centrifugal forces to exclusively drive the liquid outward, the guide structure creates a counteracting flow path that delivers liquid to the shaft seal location, thereby preventing air pocket formation.
3Ease of operation
If the shaft seal operates without sufficient liquid flow medium contact during startup, then the pump can start, but the shaft seal experiences increased wear and material tension
Solution Approach 1:
The guide structure is designed to immediately redirect liquid flow medium to the shaft seal upon pump startup. This preliminary action ensures that the shaft seal is lubricated and cooled from the very beginning of operation, preventing the development of dry running conditions that would otherwise cause increased wear and material tension during the startup phase.
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 effectively reduces the duration of dry running periods, enhances lubrication and cooling of the shaft seal, and prevents air pocket formation, thereby increasing the durability and reliability of the centrifugal pump, especially during startup operations.
Implementation Method 1
the liquid flow medium moves along the radially outer areas because of the centrifugal forces whereas the air content collects in the radially inner area that is around the shaft seal
Data Source
AI summary
In a centrifugal pump, in particular a radial or semi-axial pump including a housing with a pump chamber and a dry chamber, a drive shaft rotatably supported in the housing and connected to an impeller for pumping a liquid flow medium disposed in the pump chamber and a shaft seal arranged in an inner radial area for sealing the dry space with respect to the flow medium, a seal carrier is provided with a guide structure by which fluid flow medium is conducted from an outer radial area to an inner radial area for directing flow medium into the seal for lubrication and cooling of the seal.