Canned Molten Salt Pump With Magnetic Bearings and Solid-Bar Windings
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Solution Overview
Problem
Molten salt reactors face challenges with high-temperature operation, corrosion, and radiation, leading to issues with pump reliability, dynamic seal leakage, and the inability of existing electric motors and generators to function effectively due to the aggressive environment and high temperatures.
Innovation Solution
A canned rotodynamic flow machine with induction or reluctance motors and generators using solid copper bars for stator windings, insulated by ceramic spacers, and active magnetic bearings, which allows for operation at high temperatures without dynamic seals and reduces the risk of leakage and electrical arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are used for the electric motor driving the pump, then the motor can provide sufficient torque and power, but the magnets start to irreversibly lose their magnetism at high temperatures above 80°C
Solution Approach 1:
The patent replaces permanent magnets with an active magnetic bearing system that uses electromagnetic fields generated by stator windings to provide both motor drive and bearing support functions. This eliminates the temperature sensitivity of permanent magnets while maintaining the required magnetic field generation capability for pump operation at high temperatures up to 700°C
Solution Approach 2:
The patent combines the motor drive function and bearing support function into a single integrated active magnetic bearing system. The stator windings generate rotating magnetic fields that simultaneously provide torque for pump operation and magnetic levitation for bearing support, eliminating the need for separate permanent magnets and mechanical bearings
2Ease of repair
If dynamic seals are used in the pump, then the pump can be disassembled and maintained, but the seals are not available for high temperature ranges and aggressive environments and are much less reliable than static seals
Solution Approach 1:
The patent replaces mechanical dynamic seals with a canned pump design where the motor and pump are integrated in a sealed housing filled with inert gas. This eliminates the need for dynamic seals that fail at high temperatures, while the entire assembly can be replaced as a unit to maintain reliability
Solution Approach 2:
The patent uses an inert gas atmosphere within the canned pump housing to prevent corrosion and chemical reactions at high temperatures. This creates a stable environment that eliminates seal failure modes related to chemical degradation, allowing the pump to operate reliably in aggressive molten salt environments
3Ease of operation
If the electric motor is cooled below the operating temperature of the molten salt medium, then the motor can operate, but the salt vapor deposits on cold surfaces within the dynamic seal or motor, resulting in shorter life-cycle and increased risk of leakage
Solution Approach 1:
The patent fills the canned pump housing with inert gas that is maintained at the same high temperature as the molten salt medium. This eliminates temperature differentials that cause salt vapor condensation, while the inert atmosphere prevents corrosion and chemical reactions on all surfaces
Solution Approach 2:
The patent merges the motor operating temperature with the molten salt medium temperature by using high-temperature capable components and inert gas filling. This eliminates the temperature gradient between the motor and the salt medium, preventing condensation and extending the life-cycle of the equipment
4Power
If insulated wires are used for stator windings, then the motor can function, but there are no suitable insulation materials that can handle operating temperatures above 500°C in molten salt environments
Solution Approach 1:
The patent replaces insulated wire windings with sparsely wound stator windings that use air or inert gas as the insulating medium. This eliminates the need for high-temperature insulation materials, allowing the motor to operate at temperatures above 500°C in molten salt environments while maintaining electrical isolation between windings
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 enables stable and reliable operation of pumps and generators at high temperatures, reducing leakage risks and extending equipment lifespan by using solid copper bars and active magnetic bearings, suitable for molten salt reactors.
Implementation Method 1
active magnetic bearing for use in a flow machine for operating with a working fluid such as molten salt
Implementation Method 2
induction or reluctance motors and generators using solid copper bars for stator windings
Data Source
AI summary
A canned rotodynamic flow machine (1) configured for operating with a working fluid such as molten salt of a molten salt nuclear reactor. The stator windings are formed by one or more electrically conductive solid bars (12).