Centrifugal Pump Face Seal for Thermal Expansion Compensation
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Solution Overview
Problem
Centrifugal pumps operating in wide temperature ranges face challenges due to differential thermal expansion of components, leading to stresses and reduced sealing effectiveness, particularly in ceramic-based mechanical seals which are prone to mechanical failure and leakage.
Innovation Solution
Incorporating a metal clamping device with a radial holding mechanism, comprising a metal ring element and ceramic sealing elements, to compensate for thermal expansion forces and maintain the sealing surface integrity, preventing axial displacement and ensuring constant sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic seal rings are used in a mechanical seal for high-temperature applications, then service life and sealing effectiveness are improved, but thermal expansion stresses cause tilting and mechanical failure
Solution Approach 1:
The mechanical seal combines ceramic seal rings (for high-temperature resistance and sealing effectiveness) with a metal clamping device (for thermal expansion compensation and mechanical strength). This composite structure allows each material to perform its optimal function: ceramic provides heat resistance and sealing, while metal absorbs thermal stresses and prevents tilting, thereby resolving the contradiction between sealing effectiveness and mechanical stress resistance
Solution Approach 2:
The metal clamping device is designed with specific elastic properties and geometric parameters (thickness, modulus of elasticity, Poisson's ratio) that allow it to deform elastically under thermal expansion, compensating for dimensional changes in the ceramic seal rings. By carefully selecting material parameters and geometric dimensions, the device maintains seal integrity while accommodating thermal effects
2Temperature
If ceramic seal rings are used in wide temperature ranges, then high-temperature sealing is achieved, but differential thermal expansion causes tilting of the sliding ring
Solution Approach 1:
The metal clamping device is specifically designed to utilize thermal expansion compensation. As temperature increases, the metal device expands elastically, counteracting the differential thermal expansion between the ceramic seal rings and their mounting structures. This elastic deformation maintains the parallelism of sealing surfaces throughout the operating temperature range, preventing tilting while enabling high-temperature operation
3Reliability
If metal clamping device is added to compensate for thermal expansion, then sealing surface integrity is maintained, but device complexity increases
Solution Approach 1:
The metal clamping device functions as a flexible elastic element that compensates for thermal expansion through controlled deformation. This thin-walled elastic structure provides the necessary compliance to maintain sealing surface integrity while adding minimal structural complexity. The device's simplicity lies in its ability to use elastic deformation rather than complex mechanical adjustments
Solution Approach 2:
The metal clamping device automatically compensates for thermal expansion effects without requiring external control systems or complex mechanisms. The elastic deformation occurs passively in response to temperature changes, self-regulating the seal pressure and maintaining parallelism. This self-compensating mechanism reduces overall system complexity while ensuring reliable sealing performance across varying temperatures
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 minimizes leakage and reduces mechanical stress on ceramic components, extending the service life of the mechanical seal by maintaining the sealing surface parallelism and preventing material failure, thus ensuring reliable operation across varying temperatures.
Implementation Method 1
the individual components expand, which differ depending on the material. This can lead to stresses at crucial points and, as a result, to unfavorable geometric configurations
Data Source
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AI summary
The invention relates to a centrifugal pump for conveying hot fluids, comprising a shaft seal that is contacting and arranged in the region of the shaft feed-through, arranged in a sealing housing, wherein the shaft seal has a first fixed part that is stationarily connected to the sealing housing and wherein the shaft seal has a second rotating part that is stationarily connected to the shaft, wherein the first and the second part delimit the sealing gap, wherein the first and the second part are pressed against one another via the differential pressure to be sealed, wherein the first and/or the second part consist of multiple means arranged inside one another, in particular a metal retaining means, a ceramic sealing means and a metal clamping means.