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Working principle of magnetic pump The magnetic pump consists of three parts: pump, magnetic actuator and electric motor. The key component of the magnetic actuator is composed of an outer magnetic rotor, an inner magnetic rotor and a non-magnetic isolation sleeve. When the motor drives the outer magnetic rotor to rotate, the magnetic field can penetrate the air gap and non-magnetic materials, driving the inner magnetic rotor connected to the impeller to rotate synchronously, realizing contactless transmission of power and converting the dynamic seal into a static seal. Since the pump shaft and internal magnetic rotor are completely enclosed by the pump body and isolation sleeve, * * * * It solves the problems of "running, popping, dripping and leaking", eliminates the safety hazards of flammable, explosive, toxic and harmful media leaking through the pump seal in the refining and chemical industry, and effectively guarantees the physical and mental health of employees and safe production. 1. Working principle of magnetic pump: n pairs of magnets (n is an even number) are regularly arranged and assembled on the inner and outer magnetic rotors of the magnetic actuator, so that the magnet parts form a complete coupled magnetic system. When the inner and outer magnetic poles are opposite to each other, that is, the displacement angle Φ between the two magnetic poles = 0, the magnetic energy of the magnetic system at this time * * * * ； When the magnetic poles rotate to face each other with the same pole, that is, the displacement angle between the two magnetic poles Φ = 2π/n, the magnetic energy of the magnetic system at this time * * * * . After the external force is removed, the magnetic force will return the magnet to its magnetic energy because the poles of the magnetic system repel each other. * * * * status. Then the magnet moves and drives the magnetic rotor to rotate. 2. Structural features 1. Permanent magnets made of rare earth permanent magnet materials have a wide operating temperature range (-45-400°C), high coercive force, good anisotropy in the direction of the magnetic field, and will not demagnetize when the same poles are close to each other. They are a good magnetic field source. 2. Isolation sleeve When a metal isolation sleeve is used, the isolation sleeve is in a sinusoidal alternating magnetic field, and eddy currents are induced on the cross section perpendicular to the direction of the magnetic field lines and converted into heat. The expression of eddy current is: . Among them Pe - eddy current ； K—constant ； n—Rated speed of the pump ； T－magnetic transmission torque ； F - pressure inside the spacer ； D－Inner diameter of spacer ； The resistivity of a material ； —The tensile strength of the material. After the pump is designed, n and T are given by the working conditions. To reduce the eddy current, we can only consider F, D, , and other aspects. The isolation sleeve is made of non-metallic materials with high resistivity and high strength, which has a very obvious effect in reducing eddy current. 3． When the cooling lubricant flow control pump is running, a small amount of liquid must be used to flush and cool the annular area between the inner magnetic rotor and the isolation sleeve and the friction pair of the sliding bearing. The flow rate of the coolant is usually 2%-3% of the pump design flow rate. The annular area between the inner magnetic rotor and the isolation sleeve generates high heat due to eddy currents. When the cooling lubricant is insufficient or the flushing hole is not smooth or blocked, the medium temperature will be higher than the working temperature of the permanent magnet, causing the internal magnetic rotor to gradually lose its magnetism, causing the magnetic actuator to fail. When the medium is water or water-based liquid, the temperature rise in the annulus area can be maintained at 3-5℃ ； When the medium is hydrocarbon or oil, the temperature rise in the annulus area can be maintained at 5-8°C. 4． Sliding bearing magnetic pump sliding bearing materials include impregnated graphite, filled PTFE, engineering ceramics, etc. Since engineering ceramics have good heat resistance, corrosion resistance, and friction resistance, the sliding bearings of magnetic pumps are mostly made of engineering ceramics. Since engineering ceramics are brittle and have a small expansion coefficient, the bearing clearance must not be too small to avoid shaft holding accidents. Since the sliding bearings of the magnetic pump are lubricated by the transported medium, different materials should be used to make the bearings according to different media and usage conditions. 5. Protection measures: When the driven part of the magnetic actuator operates under overload or the rotor is stuck, the main and driven parts of the magnetic actuator will automatically slip off to protect the pump. At this time, the permanent magnets on the magnetic actuator will produce eddy losses and magnetic losses under the action of the alternating magnetic field of the active rotor, causing the temperature of the permanent magnets to rise and the magnetic actuator to slip and fail. 3. Advantages of magnetic pump Compared with centrifugal pumps using mechanical seals or packing seals, magnetic pumps have the following advantages. 1. The pump shaft changes from a dynamic seal to a closed static seal. * * * * Media leakage is avoided. 2． There is no need for independent lubrication and cooling water, which reduces energy consumption. 3． From coupling transmission to synchronous drag, there is no contact and friction. It has low power consumption, high efficiency, and has a damping and vibration reduction effect, which reduces the impact of motor vibration on the pump and the impact on the motor when cavitation vibration occurs in the pump. 4． When overloaded, the inner and outer magnetic rotors slip relative to each other, which protects the motor and pump. 4. Operation precautions 1. Prevent particles from entering (1) Ferromagnetic impurities and particles are not allowed to enter the magnetic actuator and bearing friction pair. (2) Flush in time after transporting media that is easy to crystallize or precipitate (fill clean water into the pump cavity after stopping the pump, and drain it after running for 1 minute) to ensure the service life of the sliding bearing. (3) When transporting media containing solid particles, it should be filtered at the inlet of the pump flow pipe. 2． Prevent demagnetization (1) The magnetic torque cannot be designed too small. (2) It should be operated under specified temperature conditions, and it is strictly forbidden for the medium temperature to exceed the standard. A platinum resistance temperature sensor can be installed on the outer surface of the isolation sleeve of the magnetic pump to detect the temperature rise in the annulus area, so as to alarm or shut down when the temperature exceeds the limit. 3． Prevent dry friction (1) Idling is strictly prohibited. (2) Evacuation of media is strictly prohibited. (3) When the outlet valve is closed, the continuous operation time of the pump shall not exceed 2 minutes to prevent the magnetic actuator from overheating and failure.