Encapsulated Magnet Assembly for Corrosive Environments
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Solution Overview
Problem
Current magnetic bearing systems used in corrosive environments, such as those in the oil and gas industry, face challenges with corrosion resistance, particularly in sour gas environments, due to non-NACE compliant materials and high electromagnetic losses, which lead to component failure and reduced operational efficiency.
Innovation Solution
The development of corrosion-resistant encapsulated magnet assemblies and processes that utilize a combination of magnetic and non-magnetic materials for the stator cans, with heat-treated welds to relieve stress, and the application of polymer barrier layers on rotor components to prevent corrosion, along with the use of NACE compliant alloys for rotor landing sleeves and backup bearing races.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic bearing systems use traditional materials in corrosive environments, then the system structure is simple, but corrosion resistance is poor leading to component failure
Solution Approach 1:
The patent applies composite materials by combining magnetic materials (for electromagnetic functionality) with non-magnetic corrosion-resistant materials (for protection against sour gas environments). This creates a hybrid material system where each material contributes its superior properties: magnetic materials provide the necessary electromagnetic characteristics while non-magnetic materials provide corrosion resistance and eliminate magnetic interference.
Solution Approach 2:
The patent segments the stator can into distinct magnetic and non-magnetic portions, allowing each segment to be optimized for its specific function. The magnetic portions are positioned where electromagnetic fields are required, while non-magnetic portions are placed where corrosion resistance is critical, eliminating the need for a single material to satisfy all requirements.
2Reliability
If magnetic bearing systems use NACE compliant materials, then corrosion resistance improves, but electromagnetic losses increase due to material properties
Solution Approach 1:
The patent applies local quality by making different portions of the stator can have different magnetic properties. Magnetic materials are used only in specific locations where electromagnetic field generation is required, while non-magnetic materials are used in other locations where they provide corrosion resistance without contributing to electromagnetic losses. This localized approach ensures electromagnetic functionality is maintained where needed while minimizing energy losses overall.
3Reliability
If magnetic bearing systems use non-magnetic materials for stator cans, then corrosion resistance improves, but electromagnetic field generation is reduced
Solution Approach 1:
The patent uses composite materials to create a stator can that combines magnetic and non-magnetic materials, allowing the structure to simultaneously provide corrosion resistance and electromagnetic field generation. The magnetic portions of the composite structure contribute to field generation while non-magnetic portions provide corrosion protection.
Solution Approach 2:
The patent applies local quality by positioning magnetic materials in specific locations within the stator can where electromagnetic field generation is most critical, while using non-magnetic materials in other locations. This spatial differentiation ensures that electromagnetic power is maintained in key areas while corrosion resistance is provided throughout the entire structure.
4Productivity
If magnetic bearing systems operate in sour gas environments, then operational efficiency is maintained, but weld stress causes component failure
Solution Approach 1:
The patent applies preliminary action by performing heat treatment of welds before the magnetic bearing system is put into service in the corrosive environment. This pre-treatment process relieves residual stresses in the weld joints that would otherwise develop during operation and lead to failure, thereby ensuring long-term operational efficiency and reliability.
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 provides fully NACE compliant magnetic bearing systems that significantly enhance corrosion resistance, reduce electromagnetic losses, and prevent component failure in corrosive environments, ensuring the longevity and reliability of turboexpanders and other turbomachinery.
Implementation Method 1
heat-treated welds to relieve stress
Implementation Method 2
application of polymer barrier layers on rotor components to prevent corrosion
Implementation Method 3
Each of the electromagnetic coils, referred to as magnetic radial bearings because they radially surround the rotor, produce a magnetic field that tends to attract the rotor shaft
Implementation Method 4
A magnetic bearing positions and supports a moving shaft using electromagnetic forces
Data Source
AI summary
The present invention provides an encapsulated magnet assembly, comprising (a) a magnet disposed within a housing, said housing comprising at least one wall and defining at least one aperture; and (b) a housing cover; the housing cover comprising a first portion made of a magnetic material and a second portion made of a non-magnetic material, wherein the housing cover is configured to hermetically seal said aperture, the first portion being fixedly attached to the second portion wherein a point of attachment is heat treated; and wherein the housing wall is formed of the non-magnetic material and is fixedly attached to the second portion of the housing cover. In one embodiment, the magnet of the encapsulated magnet assembly is a permanent magnet, and in an alternate embodiment an electromagnet. In one embodiment the encapsulated magnet assembly is a component of a stator-rotor assembly.