High Temperature Magnetic Coupling Pump Unit
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Solution Overview
Problem
High-temperature applications with liquids exceeding 350 degrees Celsius cause demagnetization of permanent magnetic materials in centrifugal pump rotors, leading to pump failure, as existing solutions require costly cooling arrangements that are cumbersome and unreliable.
Innovation Solution
A magnetic coupling design featuring an outer rotor with permanent magnets and an inner rotor made of magnetic susceptible material without permanent magnets, utilizing a cylindrical structure for magnetic flux conduction and a thermal protection layer to maintain magnetic torque and prevent demagnetization, allowing operation above 300 degrees Celsius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If permanent magnets are used in the rotor for magnetic coupling, then magnetic torque and coupling strength are improved, but the rotor becomes susceptible to demagnetization at high temperatures above 350 degrees Celsius
Solution Approach 1:
The invention extracts the permanent magnets from the inner rotor and relocates them to the outer rotor, which is positioned in the cooler region away from the high-temperature fluid. The inner rotor is replaced with magnetic susceptible material that can be magnetized by the outer rotor's permanent magnets, thereby maintaining magnetic coupling functionality while eliminating the demagnetization problem in the high-temperature environment.
Solution Approach 2:
The invention introduces magnetic susceptible material as an intermediary between the permanent magnets and the high-temperature fluid environment. This intermediary material can be magnetized by the permanent magnets to produce the necessary magnetic field for coupling, while itself being resistant to demagnetization at high temperatures.
2Reliability
If cooling arrangements are added to protect permanent magnets from demagnetization, then temperature control and magnetic material protection are improved, but device complexity and cost increase
Solution Approach 1:
The invention removes the need for cooling arrangements by extracting the permanent magnets from the high-temperature zone. The outer rotor with permanent magnets is positioned in the cooler region, eliminating thermal stress on the magnetic material and making cooling systems unnecessary.
Solution Approach 2:
The invention replaces the mechanical cooling system with a magnetic field-based solution. Instead of using mechanical cooling to protect permanent magnets, the system uses the magnetic properties of the outer rotor to magnetize the inner rotor's magnetic susceptible material, thereby maintaining coupling without thermal management infrastructure.
3Force
If the inner rotor contains permanent magnetic material, then magnetic coupling strength is improved, but the pump cannot operate reliably at temperatures exceeding 350 degrees Celsius
Solution Approach 1:
The invention extracts permanent magnetic material from the inner rotor and relocates it to the outer rotor. The inner rotor uses magnetic susceptible material that does not suffer from demagnetization at high temperatures, while the outer rotor with permanent magnets operates in the cooler region, enabling reliable operation above 350 degrees Celsius.
Solution Approach 2:
The invention applies different magnetic material properties to different locations: the outer rotor uses permanent magnets where temperature is lower, while the inner rotor uses magnetic susceptible material that can withstand high temperatures. This local differentiation of material properties allows the system to function reliably across the temperature gradient.
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 design increases the working temperature range of centrifugal pumps by preventing demagnetization and maintaining magnetic torque, reducing costs and complexity while ensuring reliable operation in high-temperature environments.
Implementation Method 1
Magnetic couplings are also known and such couplings are made with an inner and an outer rotor, where both rotor have permanent magnets attached in a configuration so magnetic forces ensure the coupling between the two rotors.
Implementation Method 2
the cylindrical structure being made of a magnetic susceptible material for conducting a magnetic flux between the plurality of magnetic poles
Implementation Method 3
The inner rotor is free from permanent magnetic material... The inner rotor is made of a magnetic susceptible material
Data Source
Figure 1~2
Figure 3
Figure 4~4a
AI summary
The present invention relates to a pump unit (300), with at least one impeller, comprising a coupling, wherein the coupling is mechanically connected to the at least one impeller via an inner rotor and where an outer rotor is connected to an electricalmachine arranged to produce a rotational torque, said pump being arranged to circulate a hot fluid by the impeller.The coupling includes an outer rotor including a plurality of permanent magnets (101,201) arranged to form a plurality of magnetic poles (105, 205),and an inner rotor (110, 210),whereby the outer rotor and the inner rotor are located coaxially to one another around an axis (130, 230) and spaced apart from one another by an air gap (150,250).A rotor can (330) is arranged in the air gap (250, 150) between the inner rotor and the outer rotor, so as to make a dividing section between the inner and outer rotor.Each of the plurality of magnetic poles comprisesat least a section with a radial magnetic direction in respect of the axis (130, 230) and at least a section with a magnetic direction angled between a radial direction and a tangential direction in respect of the axis (130, 230), wherein the combined length of the sides of the plurality of permanent magnets cover less than 75% of the circumference of the cylindrical structure. The outer rotor has a cylindrical structure (120, 220) surrounding the plurality of magnetic poles (105, 205), and the cylindricalstructure is made of a magnetic susceptible material for conducting a magnetic flux between the plurality of magnetic poles (105, 205) The inner rotor (110, 210) is made of a magnetic susceptible material and free from permanent magnetic material, whereinthe inner rotor is formed with multiple radial projections (111, 211) acting as salient inner rotor poles distributed around the axis (130, 230) of the inner rotor. The invention also relates to a coupling with the above mentioned coupling features.