Centrifugal Pump Sealing Gap with Rolling Wear Protection
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Solution Overview
Problem
Centrifugal pumps face challenges in maintaining a small gap between rotating and non-rotating elements to minimize efficiency losses and prevent wear, as manufacturing tolerances and operational influences often lead to contact and material wear during startup and shutdown.
Innovation Solution
The implementation of rotatably mounted bodies, such as balls or cylinders, within a form-fitting structure on the non-rotating element, which can absorb friction forces and convert them into rotational movements, preventing wear by allowing rolling movements and maintaining a small gap size, potentially produced using additive manufacturing processes like selective laser melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gap between rotating element and non-rotating element is made small to minimize efficiency losses, then pump efficiency is improved, but wear and contact between elements occur during operation
Solution Approach 1:
The patent introduces a liquid film as an intermediary substance between the rotating element and non-rotating element. This liquid film acts as a mediator that prevents direct contact and wear between the elements while maintaining a small effective gap for efficient sealing and throttling function.
Solution Approach 2:
The patent changes the physical state and properties of the sealing interface by introducing a liquid film with specific viscosity and flow characteristics. This parameter change allows the system to maintain a small gap for efficiency while the liquid film's properties prevent direct contact and wear during operation.
2Manufacturing precision
If manufacturing tolerances are tightened to achieve smaller gap, then sealing efficiency is improved, but production cost and complexity increase
Solution Approach 1:
The patent changes the approach from controlling geometric parameters (gap width) to controlling fluid parameters (liquid film properties). This allows achieving the desired sealing effect through fluid viscosity and flow control rather than through tight manufacturing tolerances on the gap dimensions.
Solution Approach 2:
By introducing the liquid film as an intermediary, the system becomes less sensitive to manufacturing tolerances. The liquid film compensates for variations in gap width, allowing broader manufacturing tolerances while maintaining effective sealing and throttling performance.
3Productivity
If the gap is made small to prevent excessive flow from high pressure to low pressure chamber, then flow control is improved, but contact and material wear occur during startup and shutdown
Solution Approach 1:
The liquid film serves as a protective intermediary that prevents direct contact between the rotating and non-rotating elements during all operational phases, including startup and shutdown. This mediator maintains the flow control function while protecting the elements from wear that would otherwise occur during these transient phases.
Solution Approach 2:
The liquid film provides beforehand cushioning by being present and functional before contact can occur. During startup and shutdown phases, the liquid film is already in place to cushion and prevent direct contact between elements, thereby preventing wear before it can happen.
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 minimizes leakage flow, maintains high efficiency, and prevents wear phenomena by reliably managing friction forces, thereby extending the service life and reducing maintenance costs of the centrifugal pump.
Implementation Method 1
bodies (11) which are arranged on the gap side and which can prevent brushing of the elements by rolling movements of the bodies
Data Source
AI summary
A sealing arrangement for a centrifugal pump is provided. The sealing arrangement permits a sealing gap between a rotating element such as a pump impeller and a non-rotating element such as a pump casing to be minimized, while protecting against element wear from gap reduction and element contact, particularly during transient operation such as pump start up. At least one of the rotating element and the non-rotating element is provided with a plurality of movably mounted bodies configured to rotate and maintain separate the rotating and non-rotating elements when the sealing gap is reduced. The elements and the bodies may be formed in an additive manufacturing process.