Permanent Magnet Rotor Remagnetization for Easier ESP Reclamation
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Solution Overview
Problem
Permanent magnet motors used in electric submersible pumps (ESPs) are difficult to assemble due to the strong attraction between magnets and ferromagnetic cores, leading to high manufacturing costs and low productivity, and are typically scrapped at the end of their life due to the lack of feasible methods for reclaiming and re-magnetizing demagnetized rotors.
Innovation Solution
A method for reclaiming and remagnetizing permanent magnet rotors involves heating the rotor to demagnetize the magnets, cleaning the surfaces, and using a specialized magnetizing fixture to re-magnetize the magnets without disassembling the rotor, allowing for safer assembly and reconditioning of the rotors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high strength permanent magnets are used in the rotor, then power density and efficiency are improved, but assembly difficulty and manufacturing cost increase due to strong attraction between magnets and ferromagnetic core
Solution Approach 1:
The patent applies preliminary action by assembling the rotor components (ferromagnetic core, magnets, and retaining structure) in a specific sequence before final magnetization. The retaining structure is pre-installed on the ferromagnetic core, and magnets are positioned in grooves before the assembly is subjected to strong magnetic fields for final magnetization. This preliminary arrangement allows safe assembly without requiring the magnets to be fully magnetized during the assembly process, thereby reducing assembly difficulty while maintaining high power density.
2Loss of energy
If high strength permanent magnets are used in the rotor, then efficiency and power factor are improved, but manufacturing cost increases due to need for specialized facilities and experienced vendors
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: (1) assembling the ferromagnetic core with grooves and the retaining structure, (2) positioning unmagnetized or weakly magnetized magnets in the grooves, (3) securing magnets with the retaining structure, and (4) final magnetization using external magnetic fields. This segmentation allows standard manufacturing facilities to perform the assembly work, while the final magnetization step can be performed using relatively simple external magnetizing equipment, thereby reducing the need for specialized facilities and experienced vendors while maintaining high efficiency.
3Reliability
If a rotor becomes partially demagnetized, then it cannot function efficiently, but magnetic particles cannot be effectively cleaned from the rotor making reclamation difficult
Solution Approach 1:
The patent applies parameter changes by controlling the magnetic field strength and duration during the magnetization process. The magnetic field parameters are adjusted to achieve complete magnetization of the permanent magnets in the rotor. This ensures that even if magnets become partially demagnetized during operation or cleaning, the rotor can be fully remagnetized to restore its functional efficiency. The ability to control magnetic field parameters allows for complete remagnetization without leaving residual magnetic particles that would interfere with cleaning or machining operations.
4Power
If permanent magnet motors are used in ESPs, then power density and efficiency are improved, but they require variable frequency drives and complex controls to maintain stability
Solution Approach 1:
The patent applies self-service by designing the rotor with a retaining structure that automatically secures the permanent magnets in place through mechanical engagement. The retaining structure, which may include clips, tabs, or interlocking features, self-secures the magnets without requiring additional active control mechanisms or complex positioning systems. This mechanical self-securing approach simplifies the overall motor design and reduces the need for complex control systems, while still maintaining the high power density benefits of permanent magnet motors.
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 approach reduces manufacturing costs, enables the reuse of demagnetized rotors, and allows for the efficient remagnetization of permanent magnet motors, improving productivity and extending the life cycle of ESPs.
Implementation Method 1
a magnetization circuit configured to generate electrical pulses that are provided to the coils
Implementation Method 2
heating the rotor to a temperature that is above a range of elastic magnetism for the material of the magnets and that does not exceed a Curie temperature of the magnet material, so as to demagnetize the permanent magnets of the rotor
Data Source
AI summary
Systems and methods for reclaiming and remagnetizing permanent magnet motors such as may be used in electric submersible pumps. In one embodiment, a method includes removing a permanent magnet rotor assembly from a motor and heating the rotor to burn off the residual oil and evaporate water in between laminations of the rotor and on the rotor surface. The rotor should be heated to a temperature that is above a flashpoint of oil on the rotor and below a Curie temperature of a material of a set of permanent magnets in the rotor (e.g., at least 600° F. for at least 12 hours). The heating may partially or fully demagnetize the permanent magnets in the rotor. The exposed surfaces of the rotor are then cleaned and the permanent magnets in the rotor are remagnetized using a specialized magnetizing fixture.