Analysis of demagnetization phenomenon in magnetic pumps

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This post was last edited by kingberg on 2011-6-18 at 15:16. A magnetic centrifugal pump (abbreviated as magnetic pump) is a type of chemical process pump that utilizes modern principles of magnetism to achieve contactless, indirect transmission through the use of permanent magnets. When the motor drives the outer rotor (i.e., the outer magnet) assembly to rotate, the magnetic field causes magnetic flux lines to pass through the isolation sleeve, thereby driving the inner rotor (i.e., the inner magnet) assembly and the impeller to rotate in sync. The medium remains completely enclosed within the stationary isolation sleeve, thus achieving leak-free pumping of the medium. This approach completely eliminates the shaft seal leakage problem associated with mechanical drive pumps, making it a new type of industrial pump that is fully sealed, leak-free, and pollution-free. Magnetic pump is the ideal pump for use in chemical processes to prevent leaks, eliminate environmental pollution, create \"leak-free workshops\" and \"leak-free factories\", and ensure safe and civilized production. There are many reasons for the demagnetization of magnetic pump magnets. One such reason is the lack of cooling for the magnetic rotor section; since the metal separator sleeve remains stationary, the rotation of the inner and outer magnetic rotors causes the metal separator sleeve to cut through the magnetic field lines, resulting in significant magnetic eddy current losses. These losses manifest as heat, which raises the temperature of the inner and outer magnetic rotors. When the temperature reaches the demagnetization point of the magnets, they demagnetize rapidly, and this demagnetization is irreversible. After the internal and external magnetic rotors become demagnetized, the main phenomenon is the inability to transmit torque (slipping between the internal and external rotors). There is usually a separator sleeve between the two rotors; if it is made of plastic, no heat is generated, but if it is metal, heat is produced, a phenomenon known as eddy current heating. Some precious metals also do not generate heat (or produce very little heat that can be ignored), such as titanium alloys and Hastelloy. Another possibility is that the motor is overloaded, meaning that the torque transmitted by the equipment is too high, which leads to demagnetization. The sound produced during demagnetization is usually dull, like a \"whooshing\" sound. Continuous operation in this condition can cause the magnets to become demagnetized. Some of the magnets lose their magnetism, which allows the pump to rotate (this is possible without load; it certainly won’t work under load). In high-quality magnetic pumps, the inner and outer magnetic rotors rotate synchronously (with a slight angular difference between them). If the torque at the drive end is too high and the drive end gets stuck, it can cause the inner and outer magnetic rotors to separate from each other. Once they separate, the pump continues to operate, and the temperature rises rapidly, which quickly leads to demagnetization. Another important reason for demagnetization in magnetic pumps is related to the properties of the magnets themselves. Generally speaking, the magnetic energy product of a magnetic material is an indicator of how easily it loses its magnetism. The Curie temperature determines a material’s resistance to temperature changes. To avoid demagnetization, it is necessary to use magnetic rotor components made from high-quality materials. Additionally, attention should be paid to proper cooling of the magnetic rotors, as well as ensuring that there are no free iron particles in their vicinity.